Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
fbb9ce95 IM |
2 | /* |
3 | * kernel/lockdep.c | |
4 | * | |
5 | * Runtime locking correctness validator | |
6 | * | |
7 | * Started by Ingo Molnar: | |
8 | * | |
4b32d0a4 | 9 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
90eec103 | 10 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
fbb9ce95 IM |
11 | * |
12 | * this code maps all the lock dependencies as they occur in a live kernel | |
13 | * and will warn about the following classes of locking bugs: | |
14 | * | |
15 | * - lock inversion scenarios | |
16 | * - circular lock dependencies | |
17 | * - hardirq/softirq safe/unsafe locking bugs | |
18 | * | |
19 | * Bugs are reported even if the current locking scenario does not cause | |
20 | * any deadlock at this point. | |
21 | * | |
22 | * I.e. if anytime in the past two locks were taken in a different order, | |
23 | * even if it happened for another task, even if those were different | |
24 | * locks (but of the same class as this lock), this code will detect it. | |
25 | * | |
26 | * Thanks to Arjan van de Ven for coming up with the initial idea of | |
27 | * mapping lock dependencies runtime. | |
28 | */ | |
a5e25883 | 29 | #define DISABLE_BRANCH_PROFILING |
fbb9ce95 IM |
30 | #include <linux/mutex.h> |
31 | #include <linux/sched.h> | |
e6017571 | 32 | #include <linux/sched/clock.h> |
29930025 | 33 | #include <linux/sched/task.h> |
6d7225f0 | 34 | #include <linux/sched/mm.h> |
fbb9ce95 IM |
35 | #include <linux/delay.h> |
36 | #include <linux/module.h> | |
37 | #include <linux/proc_fs.h> | |
38 | #include <linux/seq_file.h> | |
39 | #include <linux/spinlock.h> | |
40 | #include <linux/kallsyms.h> | |
41 | #include <linux/interrupt.h> | |
42 | #include <linux/stacktrace.h> | |
43 | #include <linux/debug_locks.h> | |
44 | #include <linux/irqflags.h> | |
99de055a | 45 | #include <linux/utsname.h> |
4b32d0a4 | 46 | #include <linux/hash.h> |
81d68a96 | 47 | #include <linux/ftrace.h> |
b4b136f4 | 48 | #include <linux/stringify.h> |
ace35a7a | 49 | #include <linux/bitmap.h> |
d588e461 | 50 | #include <linux/bitops.h> |
5a0e3ad6 | 51 | #include <linux/gfp.h> |
e7904a28 | 52 | #include <linux/random.h> |
dfaaf3fa | 53 | #include <linux/jhash.h> |
88f1c87d | 54 | #include <linux/nmi.h> |
a0b0fd53 | 55 | #include <linux/rcupdate.h> |
2f43c602 | 56 | #include <linux/kprobes.h> |
f8cfa466 | 57 | #include <linux/lockdep.h> |
5a5d7e9b | 58 | #include <linux/context_tracking.h> |
af012961 | 59 | |
fbb9ce95 IM |
60 | #include <asm/sections.h> |
61 | ||
62 | #include "lockdep_internals.h" | |
63 | ||
67178767 | 64 | #include <trace/events/lock.h> |
a8d154b0 | 65 | |
f20786ff | 66 | #ifdef CONFIG_PROVE_LOCKING |
f79c9b8a | 67 | static int prove_locking = 1; |
f20786ff PZ |
68 | module_param(prove_locking, int, 0644); |
69 | #else | |
70 | #define prove_locking 0 | |
71 | #endif | |
72 | ||
73 | #ifdef CONFIG_LOCK_STAT | |
f79c9b8a | 74 | static int lock_stat = 1; |
f20786ff PZ |
75 | module_param(lock_stat, int, 0644); |
76 | #else | |
77 | #define lock_stat 0 | |
78 | #endif | |
79 | ||
f79c9b8a | 80 | #ifdef CONFIG_SYSCTL |
81 | static struct ctl_table kern_lockdep_table[] = { | |
82 | #ifdef CONFIG_PROVE_LOCKING | |
83 | { | |
84 | .procname = "prove_locking", | |
85 | .data = &prove_locking, | |
86 | .maxlen = sizeof(int), | |
87 | .mode = 0644, | |
88 | .proc_handler = proc_dointvec, | |
89 | }, | |
90 | #endif /* CONFIG_PROVE_LOCKING */ | |
91 | #ifdef CONFIG_LOCK_STAT | |
92 | { | |
93 | .procname = "lock_stat", | |
94 | .data = &lock_stat, | |
95 | .maxlen = sizeof(int), | |
96 | .mode = 0644, | |
97 | .proc_handler = proc_dointvec, | |
98 | }, | |
99 | #endif /* CONFIG_LOCK_STAT */ | |
100 | { } | |
101 | }; | |
102 | ||
103 | static __init int kernel_lockdep_sysctls_init(void) | |
104 | { | |
105 | register_sysctl_init("kernel", kern_lockdep_table); | |
106 | return 0; | |
107 | } | |
108 | late_initcall(kernel_lockdep_sysctls_init); | |
109 | #endif /* CONFIG_SYSCTL */ | |
110 | ||
4d004099 PZ |
111 | DEFINE_PER_CPU(unsigned int, lockdep_recursion); |
112 | EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion); | |
113 | ||
0afda3a8 | 114 | static __always_inline bool lockdep_enabled(void) |
4d004099 PZ |
115 | { |
116 | if (!debug_locks) | |
117 | return false; | |
118 | ||
d48e3850 | 119 | if (this_cpu_read(lockdep_recursion)) |
4d004099 PZ |
120 | return false; |
121 | ||
122 | if (current->lockdep_recursion) | |
123 | return false; | |
124 | ||
125 | return true; | |
126 | } | |
127 | ||
fbb9ce95 | 128 | /* |
74c383f1 IM |
129 | * lockdep_lock: protects the lockdep graph, the hashes and the |
130 | * class/list/hash allocators. | |
fbb9ce95 IM |
131 | * |
132 | * This is one of the rare exceptions where it's justified | |
133 | * to use a raw spinlock - we really dont want the spinlock | |
74c383f1 | 134 | * code to recurse back into the lockdep code... |
fbb9ce95 | 135 | */ |
248efb21 PZ |
136 | static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
137 | static struct task_struct *__owner; | |
138 | ||
139 | static inline void lockdep_lock(void) | |
140 | { | |
141 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
142 | ||
43be4388 | 143 | __this_cpu_inc(lockdep_recursion); |
248efb21 PZ |
144 | arch_spin_lock(&__lock); |
145 | __owner = current; | |
248efb21 PZ |
146 | } |
147 | ||
148 | static inline void lockdep_unlock(void) | |
149 | { | |
43be4388 BF |
150 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); |
151 | ||
248efb21 PZ |
152 | if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current)) |
153 | return; | |
154 | ||
248efb21 PZ |
155 | __owner = NULL; |
156 | arch_spin_unlock(&__lock); | |
43be4388 | 157 | __this_cpu_dec(lockdep_recursion); |
248efb21 PZ |
158 | } |
159 | ||
160 | static inline bool lockdep_assert_locked(void) | |
161 | { | |
162 | return DEBUG_LOCKS_WARN_ON(__owner != current); | |
163 | } | |
164 | ||
cdc84d79 | 165 | static struct task_struct *lockdep_selftest_task_struct; |
74c383f1 | 166 | |
248efb21 | 167 | |
74c383f1 IM |
168 | static int graph_lock(void) |
169 | { | |
248efb21 | 170 | lockdep_lock(); |
74c383f1 IM |
171 | /* |
172 | * Make sure that if another CPU detected a bug while | |
173 | * walking the graph we dont change it (while the other | |
174 | * CPU is busy printing out stuff with the graph lock | |
175 | * dropped already) | |
176 | */ | |
177 | if (!debug_locks) { | |
248efb21 | 178 | lockdep_unlock(); |
74c383f1 IM |
179 | return 0; |
180 | } | |
181 | return 1; | |
182 | } | |
183 | ||
248efb21 | 184 | static inline void graph_unlock(void) |
74c383f1 | 185 | { |
248efb21 | 186 | lockdep_unlock(); |
74c383f1 IM |
187 | } |
188 | ||
189 | /* | |
190 | * Turn lock debugging off and return with 0 if it was off already, | |
191 | * and also release the graph lock: | |
192 | */ | |
193 | static inline int debug_locks_off_graph_unlock(void) | |
194 | { | |
195 | int ret = debug_locks_off(); | |
196 | ||
248efb21 | 197 | lockdep_unlock(); |
74c383f1 IM |
198 | |
199 | return ret; | |
200 | } | |
fbb9ce95 | 201 | |
fbb9ce95 | 202 | unsigned long nr_list_entries; |
af012961 | 203 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; |
ace35a7a | 204 | static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); |
fbb9ce95 | 205 | |
fbb9ce95 IM |
206 | /* |
207 | * All data structures here are protected by the global debug_lock. | |
208 | * | |
a0b0fd53 BVA |
209 | * nr_lock_classes is the number of elements of lock_classes[] that is |
210 | * in use. | |
fbb9ce95 | 211 | */ |
108c1485 BVA |
212 | #define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
213 | #define KEYHASH_SIZE (1UL << KEYHASH_BITS) | |
214 | static struct hlist_head lock_keys_hash[KEYHASH_SIZE]; | |
fbb9ce95 | 215 | unsigned long nr_lock_classes; |
1d44bcb4 | 216 | unsigned long nr_zapped_classes; |
fb7275ac | 217 | unsigned long max_lock_class_idx; |
8ca2b56c | 218 | struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; |
fb7275ac | 219 | DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); |
fbb9ce95 | 220 | |
f82b217e DJ |
221 | static inline struct lock_class *hlock_class(struct held_lock *hlock) |
222 | { | |
01bb6f0a YD |
223 | unsigned int class_idx = hlock->class_idx; |
224 | ||
225 | /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */ | |
226 | barrier(); | |
227 | ||
228 | if (!test_bit(class_idx, lock_classes_in_use)) { | |
0119fee4 PZ |
229 | /* |
230 | * Someone passed in garbage, we give up. | |
231 | */ | |
f82b217e DJ |
232 | DEBUG_LOCKS_WARN_ON(1); |
233 | return NULL; | |
234 | } | |
01bb6f0a YD |
235 | |
236 | /* | |
237 | * At this point, if the passed hlock->class_idx is still garbage, | |
238 | * we just have to live with it | |
239 | */ | |
240 | return lock_classes + class_idx; | |
f82b217e DJ |
241 | } |
242 | ||
f20786ff | 243 | #ifdef CONFIG_LOCK_STAT |
25528213 | 244 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats); |
f20786ff | 245 | |
3365e779 PZ |
246 | static inline u64 lockstat_clock(void) |
247 | { | |
c676329a | 248 | return local_clock(); |
3365e779 PZ |
249 | } |
250 | ||
c7e78cff | 251 | static int lock_point(unsigned long points[], unsigned long ip) |
f20786ff PZ |
252 | { |
253 | int i; | |
254 | ||
c7e78cff PZ |
255 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
256 | if (points[i] == 0) { | |
257 | points[i] = ip; | |
f20786ff PZ |
258 | break; |
259 | } | |
c7e78cff | 260 | if (points[i] == ip) |
f20786ff PZ |
261 | break; |
262 | } | |
263 | ||
264 | return i; | |
265 | } | |
266 | ||
3365e779 | 267 | static void lock_time_inc(struct lock_time *lt, u64 time) |
f20786ff PZ |
268 | { |
269 | if (time > lt->max) | |
270 | lt->max = time; | |
271 | ||
109d71c6 | 272 | if (time < lt->min || !lt->nr) |
f20786ff PZ |
273 | lt->min = time; |
274 | ||
275 | lt->total += time; | |
276 | lt->nr++; | |
277 | } | |
278 | ||
c46261de PZ |
279 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
280 | { | |
109d71c6 FR |
281 | if (!src->nr) |
282 | return; | |
283 | ||
284 | if (src->max > dst->max) | |
285 | dst->max = src->max; | |
286 | ||
287 | if (src->min < dst->min || !dst->nr) | |
288 | dst->min = src->min; | |
289 | ||
c46261de PZ |
290 | dst->total += src->total; |
291 | dst->nr += src->nr; | |
292 | } | |
293 | ||
294 | struct lock_class_stats lock_stats(struct lock_class *class) | |
295 | { | |
296 | struct lock_class_stats stats; | |
297 | int cpu, i; | |
298 | ||
299 | memset(&stats, 0, sizeof(struct lock_class_stats)); | |
300 | for_each_possible_cpu(cpu) { | |
301 | struct lock_class_stats *pcs = | |
1871e52c | 302 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
c46261de PZ |
303 | |
304 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) | |
305 | stats.contention_point[i] += pcs->contention_point[i]; | |
306 | ||
c7e78cff PZ |
307 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
308 | stats.contending_point[i] += pcs->contending_point[i]; | |
309 | ||
c46261de PZ |
310 | lock_time_add(&pcs->read_waittime, &stats.read_waittime); |
311 | lock_time_add(&pcs->write_waittime, &stats.write_waittime); | |
312 | ||
313 | lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); | |
314 | lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); | |
96645678 PZ |
315 | |
316 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) | |
317 | stats.bounces[i] += pcs->bounces[i]; | |
c46261de PZ |
318 | } |
319 | ||
320 | return stats; | |
321 | } | |
322 | ||
323 | void clear_lock_stats(struct lock_class *class) | |
324 | { | |
325 | int cpu; | |
326 | ||
327 | for_each_possible_cpu(cpu) { | |
328 | struct lock_class_stats *cpu_stats = | |
1871e52c | 329 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
c46261de PZ |
330 | |
331 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); | |
332 | } | |
333 | memset(class->contention_point, 0, sizeof(class->contention_point)); | |
c7e78cff | 334 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
c46261de PZ |
335 | } |
336 | ||
f20786ff PZ |
337 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
338 | { | |
01f38497 | 339 | return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes]; |
f20786ff PZ |
340 | } |
341 | ||
342 | static void lock_release_holdtime(struct held_lock *hlock) | |
343 | { | |
344 | struct lock_class_stats *stats; | |
3365e779 | 345 | u64 holdtime; |
f20786ff PZ |
346 | |
347 | if (!lock_stat) | |
348 | return; | |
349 | ||
3365e779 | 350 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
f20786ff | 351 | |
f82b217e | 352 | stats = get_lock_stats(hlock_class(hlock)); |
f20786ff PZ |
353 | if (hlock->read) |
354 | lock_time_inc(&stats->read_holdtime, holdtime); | |
355 | else | |
356 | lock_time_inc(&stats->write_holdtime, holdtime); | |
f20786ff PZ |
357 | } |
358 | #else | |
359 | static inline void lock_release_holdtime(struct held_lock *hlock) | |
360 | { | |
361 | } | |
362 | #endif | |
363 | ||
fbb9ce95 | 364 | /* |
a0b0fd53 BVA |
365 | * We keep a global list of all lock classes. The list is only accessed with |
366 | * the lockdep spinlock lock held. free_lock_classes is a list with free | |
367 | * elements. These elements are linked together by the lock_entry member in | |
368 | * struct lock_class. | |
fbb9ce95 | 369 | */ |
fb7275ac | 370 | static LIST_HEAD(all_lock_classes); |
a0b0fd53 BVA |
371 | static LIST_HEAD(free_lock_classes); |
372 | ||
373 | /** | |
374 | * struct pending_free - information about data structures about to be freed | |
375 | * @zapped: Head of a list with struct lock_class elements. | |
de4643a7 BVA |
376 | * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements |
377 | * are about to be freed. | |
a0b0fd53 BVA |
378 | */ |
379 | struct pending_free { | |
380 | struct list_head zapped; | |
de4643a7 | 381 | DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS); |
a0b0fd53 BVA |
382 | }; |
383 | ||
384 | /** | |
385 | * struct delayed_free - data structures used for delayed freeing | |
386 | * | |
387 | * A data structure for delayed freeing of data structures that may be | |
388 | * accessed by RCU readers at the time these were freed. | |
389 | * | |
390 | * @rcu_head: Used to schedule an RCU callback for freeing data structures. | |
391 | * @index: Index of @pf to which freed data structures are added. | |
392 | * @scheduled: Whether or not an RCU callback has been scheduled. | |
393 | * @pf: Array with information about data structures about to be freed. | |
394 | */ | |
395 | static struct delayed_free { | |
396 | struct rcu_head rcu_head; | |
397 | int index; | |
398 | int scheduled; | |
399 | struct pending_free pf[2]; | |
400 | } delayed_free; | |
fbb9ce95 IM |
401 | |
402 | /* | |
403 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
404 | */ | |
405 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
406 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
4b32d0a4 | 407 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
fbb9ce95 IM |
408 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
409 | ||
a63f38cc | 410 | static struct hlist_head classhash_table[CLASSHASH_SIZE]; |
fbb9ce95 | 411 | |
fbb9ce95 IM |
412 | /* |
413 | * We put the lock dependency chains into a hash-table as well, to cache | |
414 | * their existence: | |
415 | */ | |
416 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
417 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
4b32d0a4 | 418 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
fbb9ce95 IM |
419 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
420 | ||
a63f38cc | 421 | static struct hlist_head chainhash_table[CHAINHASH_SIZE]; |
fbb9ce95 | 422 | |
f611e8cf BF |
423 | /* |
424 | * the id of held_lock | |
425 | */ | |
426 | static inline u16 hlock_id(struct held_lock *hlock) | |
427 | { | |
428 | BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16); | |
429 | ||
430 | return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS)); | |
431 | } | |
432 | ||
433 | static inline unsigned int chain_hlock_class_idx(u16 hlock_id) | |
434 | { | |
435 | return hlock_id & (MAX_LOCKDEP_KEYS - 1); | |
436 | } | |
437 | ||
fbb9ce95 IM |
438 | /* |
439 | * The hash key of the lock dependency chains is a hash itself too: | |
440 | * it's a hash of all locks taken up to that lock, including that lock. | |
441 | * It's a 64-bit hash, because it's important for the keys to be | |
442 | * unique. | |
443 | */ | |
dfaaf3fa PZ |
444 | static inline u64 iterate_chain_key(u64 key, u32 idx) |
445 | { | |
446 | u32 k0 = key, k1 = key >> 32; | |
447 | ||
448 | __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */ | |
449 | ||
450 | return k0 | (u64)k1 << 32; | |
451 | } | |
fbb9ce95 | 452 | |
e196e479 YD |
453 | void lockdep_init_task(struct task_struct *task) |
454 | { | |
455 | task->lockdep_depth = 0; /* no locks held yet */ | |
f6ec8829 | 456 | task->curr_chain_key = INITIAL_CHAIN_KEY; |
e196e479 YD |
457 | task->lockdep_recursion = 0; |
458 | } | |
459 | ||
4d004099 PZ |
460 | static __always_inline void lockdep_recursion_inc(void) |
461 | { | |
462 | __this_cpu_inc(lockdep_recursion); | |
463 | } | |
464 | ||
6eebad1a | 465 | static __always_inline void lockdep_recursion_finish(void) |
10476e63 | 466 | { |
4d004099 PZ |
467 | if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion))) |
468 | __this_cpu_write(lockdep_recursion, 0); | |
10476e63 PZ |
469 | } |
470 | ||
cdc84d79 BVA |
471 | void lockdep_set_selftest_task(struct task_struct *task) |
472 | { | |
473 | lockdep_selftest_task_struct = task; | |
474 | } | |
475 | ||
fbb9ce95 IM |
476 | /* |
477 | * Debugging switches: | |
478 | */ | |
479 | ||
480 | #define VERBOSE 0 | |
33e94e96 | 481 | #define VERY_VERBOSE 0 |
fbb9ce95 IM |
482 | |
483 | #if VERBOSE | |
484 | # define HARDIRQ_VERBOSE 1 | |
485 | # define SOFTIRQ_VERBOSE 1 | |
486 | #else | |
487 | # define HARDIRQ_VERBOSE 0 | |
488 | # define SOFTIRQ_VERBOSE 0 | |
489 | #endif | |
490 | ||
d92a8cfc | 491 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE |
fbb9ce95 IM |
492 | /* |
493 | * Quick filtering for interesting events: | |
494 | */ | |
495 | static int class_filter(struct lock_class *class) | |
496 | { | |
f9829cce AK |
497 | #if 0 |
498 | /* Example */ | |
fbb9ce95 | 499 | if (class->name_version == 1 && |
f9829cce | 500 | !strcmp(class->name, "lockname")) |
fbb9ce95 IM |
501 | return 1; |
502 | if (class->name_version == 1 && | |
f9829cce | 503 | !strcmp(class->name, "&struct->lockfield")) |
fbb9ce95 | 504 | return 1; |
f9829cce | 505 | #endif |
a6640897 IM |
506 | /* Filter everything else. 1 would be to allow everything else */ |
507 | return 0; | |
fbb9ce95 IM |
508 | } |
509 | #endif | |
510 | ||
511 | static int verbose(struct lock_class *class) | |
512 | { | |
513 | #if VERBOSE | |
514 | return class_filter(class); | |
515 | #endif | |
516 | return 0; | |
517 | } | |
518 | ||
2c522836 DJ |
519 | static void print_lockdep_off(const char *bug_msg) |
520 | { | |
521 | printk(KERN_DEBUG "%s\n", bug_msg); | |
522 | printk(KERN_DEBUG "turning off the locking correctness validator.\n"); | |
acf59377 | 523 | #ifdef CONFIG_LOCK_STAT |
2c522836 | 524 | printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); |
acf59377 | 525 | #endif |
2c522836 DJ |
526 | } |
527 | ||
886532ae AB |
528 | unsigned long nr_stack_trace_entries; |
529 | ||
30a35f79 | 530 | #ifdef CONFIG_PROVE_LOCKING |
12593b74 BVA |
531 | /** |
532 | * struct lock_trace - single stack backtrace | |
533 | * @hash_entry: Entry in a stack_trace_hash[] list. | |
534 | * @hash: jhash() of @entries. | |
535 | * @nr_entries: Number of entries in @entries. | |
536 | * @entries: Actual stack backtrace. | |
537 | */ | |
538 | struct lock_trace { | |
539 | struct hlist_node hash_entry; | |
540 | u32 hash; | |
541 | u32 nr_entries; | |
db78538c | 542 | unsigned long entries[] __aligned(sizeof(unsigned long)); |
12593b74 BVA |
543 | }; |
544 | #define LOCK_TRACE_SIZE_IN_LONGS \ | |
545 | (sizeof(struct lock_trace) / sizeof(unsigned long)) | |
886532ae | 546 | /* |
12593b74 | 547 | * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock. |
886532ae AB |
548 | */ |
549 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
12593b74 BVA |
550 | static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE]; |
551 | ||
552 | static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2) | |
553 | { | |
554 | return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries && | |
555 | memcmp(t1->entries, t2->entries, | |
556 | t1->nr_entries * sizeof(t1->entries[0])) == 0; | |
557 | } | |
886532ae | 558 | |
12593b74 | 559 | static struct lock_trace *save_trace(void) |
fbb9ce95 | 560 | { |
12593b74 BVA |
561 | struct lock_trace *trace, *t2; |
562 | struct hlist_head *hash_head; | |
563 | u32 hash; | |
d91f3057 | 564 | int max_entries; |
fbb9ce95 | 565 | |
12593b74 BVA |
566 | BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE); |
567 | BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES); | |
568 | ||
569 | trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries); | |
570 | max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries - | |
571 | LOCK_TRACE_SIZE_IN_LONGS; | |
fbb9ce95 | 572 | |
d91f3057 | 573 | if (max_entries <= 0) { |
74c383f1 | 574 | if (!debug_locks_off_graph_unlock()) |
12593b74 | 575 | return NULL; |
74c383f1 | 576 | |
2c522836 | 577 | print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); |
74c383f1 IM |
578 | dump_stack(); |
579 | ||
12593b74 | 580 | return NULL; |
fbb9ce95 | 581 | } |
d91f3057 | 582 | trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3); |
fbb9ce95 | 583 | |
12593b74 BVA |
584 | hash = jhash(trace->entries, trace->nr_entries * |
585 | sizeof(trace->entries[0]), 0); | |
586 | trace->hash = hash; | |
587 | hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1)); | |
588 | hlist_for_each_entry(t2, hash_head, hash_entry) { | |
589 | if (traces_identical(trace, t2)) | |
590 | return t2; | |
591 | } | |
592 | nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries; | |
593 | hlist_add_head(&trace->hash_entry, hash_head); | |
594 | ||
595 | return trace; | |
fbb9ce95 | 596 | } |
8c779229 BVA |
597 | |
598 | /* Return the number of stack traces in the stack_trace[] array. */ | |
599 | u64 lockdep_stack_trace_count(void) | |
600 | { | |
601 | struct lock_trace *trace; | |
602 | u64 c = 0; | |
603 | int i; | |
604 | ||
605 | for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) { | |
606 | hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) { | |
607 | c++; | |
608 | } | |
609 | } | |
610 | ||
611 | return c; | |
612 | } | |
613 | ||
614 | /* Return the number of stack hash chains that have at least one stack trace. */ | |
615 | u64 lockdep_stack_hash_count(void) | |
616 | { | |
617 | u64 c = 0; | |
618 | int i; | |
619 | ||
620 | for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) | |
621 | if (!hlist_empty(&stack_trace_hash[i])) | |
622 | c++; | |
623 | ||
624 | return c; | |
fbb9ce95 | 625 | } |
886532ae | 626 | #endif |
fbb9ce95 IM |
627 | |
628 | unsigned int nr_hardirq_chains; | |
629 | unsigned int nr_softirq_chains; | |
630 | unsigned int nr_process_chains; | |
631 | unsigned int max_lockdep_depth; | |
fbb9ce95 IM |
632 | |
633 | #ifdef CONFIG_DEBUG_LOCKDEP | |
fbb9ce95 IM |
634 | /* |
635 | * Various lockdep statistics: | |
636 | */ | |
bd6d29c2 | 637 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
fbb9ce95 IM |
638 | #endif |
639 | ||
30a35f79 | 640 | #ifdef CONFIG_PROVE_LOCKING |
fbb9ce95 IM |
641 | /* |
642 | * Locking printouts: | |
643 | */ | |
644 | ||
fabe9c42 | 645 | #define __USAGE(__STATE) \ |
b4b136f4 PZ |
646 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
647 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ | |
648 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ | |
649 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", | |
fabe9c42 | 650 | |
fbb9ce95 IM |
651 | static const char *usage_str[] = |
652 | { | |
fabe9c42 PZ |
653 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
654 | #include "lockdep_states.h" | |
655 | #undef LOCKDEP_STATE | |
656 | [LOCK_USED] = "INITIAL USE", | |
2bb8945b PZ |
657 | [LOCK_USED_READ] = "INITIAL READ USE", |
658 | /* abused as string storage for verify_lock_unused() */ | |
f6f48e18 | 659 | [LOCK_USAGE_STATES] = "IN-NMI", |
fbb9ce95 | 660 | }; |
886532ae | 661 | #endif |
fbb9ce95 | 662 | |
364f6afc | 663 | const char *__get_key_name(const struct lockdep_subclass_key *key, char *str) |
fbb9ce95 | 664 | { |
ffb45122 | 665 | return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); |
fbb9ce95 IM |
666 | } |
667 | ||
3ff176ca | 668 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
fbb9ce95 | 669 | { |
3ff176ca PZ |
670 | return 1UL << bit; |
671 | } | |
fbb9ce95 | 672 | |
3ff176ca PZ |
673 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
674 | { | |
c52478f4 YD |
675 | /* |
676 | * The usage character defaults to '.' (i.e., irqs disabled and not in | |
677 | * irq context), which is the safest usage category. | |
678 | */ | |
3ff176ca PZ |
679 | char c = '.'; |
680 | ||
c52478f4 YD |
681 | /* |
682 | * The order of the following usage checks matters, which will | |
683 | * result in the outcome character as follows: | |
684 | * | |
685 | * - '+': irq is enabled and not in irq context | |
686 | * - '-': in irq context and irq is disabled | |
687 | * - '?': in irq context and irq is enabled | |
688 | */ | |
689 | if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) { | |
3ff176ca | 690 | c = '+'; |
c52478f4 | 691 | if (class->usage_mask & lock_flag(bit)) |
3ff176ca | 692 | c = '?'; |
c52478f4 YD |
693 | } else if (class->usage_mask & lock_flag(bit)) |
694 | c = '-'; | |
fbb9ce95 | 695 | |
3ff176ca PZ |
696 | return c; |
697 | } | |
cf40bd16 | 698 | |
f510b233 | 699 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
3ff176ca | 700 | { |
f510b233 | 701 | int i = 0; |
cf40bd16 | 702 | |
f510b233 PZ |
703 | #define LOCKDEP_STATE(__STATE) \ |
704 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ | |
705 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); | |
706 | #include "lockdep_states.h" | |
707 | #undef LOCKDEP_STATE | |
708 | ||
709 | usage[i] = '\0'; | |
fbb9ce95 IM |
710 | } |
711 | ||
eb1cfd09 | 712 | static void __print_lock_name(struct held_lock *hlock, struct lock_class *class) |
3003eba3 SR |
713 | { |
714 | char str[KSYM_NAME_LEN]; | |
715 | const char *name; | |
716 | ||
fbb9ce95 IM |
717 | name = class->name; |
718 | if (!name) { | |
719 | name = __get_key_name(class->key, str); | |
f943fe0f | 720 | printk(KERN_CONT "%s", name); |
fbb9ce95 | 721 | } else { |
f943fe0f | 722 | printk(KERN_CONT "%s", name); |
fbb9ce95 | 723 | if (class->name_version > 1) |
f943fe0f | 724 | printk(KERN_CONT "#%d", class->name_version); |
fbb9ce95 | 725 | if (class->subclass) |
f943fe0f | 726 | printk(KERN_CONT "/%d", class->subclass); |
eb1cfd09 KO |
727 | if (hlock && class->print_fn) |
728 | class->print_fn(hlock->instance); | |
fbb9ce95 | 729 | } |
e5e78d08 SR |
730 | } |
731 | ||
eb1cfd09 | 732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class) |
e5e78d08 SR |
733 | { |
734 | char usage[LOCK_USAGE_CHARS]; | |
735 | ||
736 | get_usage_chars(class, usage); | |
737 | ||
f943fe0f | 738 | printk(KERN_CONT " ("); |
eb1cfd09 | 739 | __print_lock_name(hlock, class); |
6d48b791 | 740 | printk(KERN_CONT "){%s}-{%d:%d}", usage, |
de8f5e4f PZ |
741 | class->wait_type_outer ?: class->wait_type_inner, |
742 | class->wait_type_inner); | |
fbb9ce95 IM |
743 | } |
744 | ||
745 | static void print_lockdep_cache(struct lockdep_map *lock) | |
746 | { | |
747 | const char *name; | |
9281acea | 748 | char str[KSYM_NAME_LEN]; |
fbb9ce95 IM |
749 | |
750 | name = lock->name; | |
751 | if (!name) | |
752 | name = __get_key_name(lock->key->subkeys, str); | |
753 | ||
f943fe0f | 754 | printk(KERN_CONT "%s", name); |
fbb9ce95 IM |
755 | } |
756 | ||
757 | static void print_lock(struct held_lock *hlock) | |
758 | { | |
d7bc3197 PZ |
759 | /* |
760 | * We can be called locklessly through debug_show_all_locks() so be | |
761 | * extra careful, the hlock might have been released and cleared. | |
01bb6f0a YD |
762 | * |
763 | * If this indeed happens, lets pretend it does not hurt to continue | |
764 | * to print the lock unless the hlock class_idx does not point to a | |
765 | * registered class. The rationale here is: since we don't attempt | |
766 | * to distinguish whether we are in this situation, if it just | |
767 | * happened we can't count on class_idx to tell either. | |
d7bc3197 | 768 | */ |
01bb6f0a | 769 | struct lock_class *lock = hlock_class(hlock); |
d7bc3197 | 770 | |
01bb6f0a | 771 | if (!lock) { |
f943fe0f | 772 | printk(KERN_CONT "<RELEASED>\n"); |
d7bc3197 PZ |
773 | return; |
774 | } | |
775 | ||
519248f3 | 776 | printk(KERN_CONT "%px", hlock->instance); |
eb1cfd09 | 777 | print_lock_name(hlock, lock); |
b3c39758 | 778 | printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip); |
fbb9ce95 IM |
779 | } |
780 | ||
8cc05c71 | 781 | static void lockdep_print_held_locks(struct task_struct *p) |
fbb9ce95 | 782 | { |
8cc05c71 | 783 | int i, depth = READ_ONCE(p->lockdep_depth); |
fbb9ce95 | 784 | |
8cc05c71 TH |
785 | if (!depth) |
786 | printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p)); | |
787 | else | |
788 | printk("%d lock%s held by %s/%d:\n", depth, | |
789 | depth > 1 ? "s" : "", p->comm, task_pid_nr(p)); | |
790 | /* | |
791 | * It's not reliable to print a task's held locks if it's not sleeping | |
792 | * and it's not the current task. | |
793 | */ | |
b03fbd4f | 794 | if (p != current && task_is_running(p)) |
fbb9ce95 | 795 | return; |
fbb9ce95 IM |
796 | for (i = 0; i < depth; i++) { |
797 | printk(" #%d: ", i); | |
8cc05c71 | 798 | print_lock(p->held_locks + i); |
fbb9ce95 IM |
799 | } |
800 | } | |
fbb9ce95 | 801 | |
fbdc4b9a | 802 | static void print_kernel_ident(void) |
8e18257d | 803 | { |
fbdc4b9a | 804 | printk("%s %.*s %s\n", init_utsname()->release, |
8e18257d | 805 | (int)strcspn(init_utsname()->version, " "), |
fbdc4b9a BH |
806 | init_utsname()->version, |
807 | print_tainted()); | |
8e18257d PZ |
808 | } |
809 | ||
810 | static int very_verbose(struct lock_class *class) | |
811 | { | |
812 | #if VERY_VERBOSE | |
813 | return class_filter(class); | |
814 | #endif | |
815 | return 0; | |
816 | } | |
817 | ||
fbb9ce95 | 818 | /* |
8e18257d | 819 | * Is this the address of a static object: |
fbb9ce95 | 820 | */ |
8dce7a9a | 821 | #ifdef __KERNEL__ |
108c1485 | 822 | static int static_obj(const void *obj) |
fbb9ce95 | 823 | { |
0a6b58c5 | 824 | unsigned long addr = (unsigned long) obj; |
8e18257d | 825 | |
0a6b58c5 HD |
826 | if (is_kernel_core_data(addr)) |
827 | return 1; | |
828 | ||
829 | /* | |
830 | * keys are allowed in the __ro_after_init section. | |
831 | */ | |
832 | if (is_kernel_rodata(addr)) | |
833 | return 1; | |
7a5da02d | 834 | |
fbb9ce95 | 835 | /* |
0a6b58c5 HD |
836 | * in initdata section and used during bootup only? |
837 | * NOTE: On some platforms the initdata section is | |
838 | * outside of the _stext ... _end range. | |
fbb9ce95 | 839 | */ |
0a6b58c5 HD |
840 | if (system_state < SYSTEM_FREEING_INITMEM && |
841 | init_section_contains((void *)addr, 1)) | |
8e18257d | 842 | return 1; |
fbb9ce95 IM |
843 | |
844 | /* | |
10fad5e4 | 845 | * in-kernel percpu var? |
fbb9ce95 | 846 | */ |
10fad5e4 TH |
847 | if (is_kernel_percpu_address(addr)) |
848 | return 1; | |
fbb9ce95 | 849 | |
8e18257d | 850 | /* |
10fad5e4 | 851 | * module static or percpu var? |
8e18257d | 852 | */ |
10fad5e4 | 853 | return is_module_address(addr) || is_module_percpu_address(addr); |
99de055a | 854 | } |
8dce7a9a | 855 | #endif |
99de055a | 856 | |
fbb9ce95 | 857 | /* |
8e18257d | 858 | * To make lock name printouts unique, we calculate a unique |
fe27b0de BVA |
859 | * class->name_version generation counter. The caller must hold the graph |
860 | * lock. | |
fbb9ce95 | 861 | */ |
8e18257d | 862 | static int count_matching_names(struct lock_class *new_class) |
fbb9ce95 | 863 | { |
8e18257d PZ |
864 | struct lock_class *class; |
865 | int count = 0; | |
fbb9ce95 | 866 | |
8e18257d | 867 | if (!new_class->name) |
fbb9ce95 IM |
868 | return 0; |
869 | ||
fe27b0de | 870 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
8e18257d PZ |
871 | if (new_class->key - new_class->subclass == class->key) |
872 | return class->name_version; | |
873 | if (class->name && !strcmp(class->name, new_class->name)) | |
874 | count = max(count, class->name_version); | |
875 | } | |
fbb9ce95 | 876 | |
8e18257d | 877 | return count + 1; |
fbb9ce95 IM |
878 | } |
879 | ||
f6f48e18 | 880 | /* used from NMI context -- must be lockless */ |
49faa777 | 881 | static noinstr struct lock_class * |
08f36ff6 | 882 | look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) |
fbb9ce95 | 883 | { |
8e18257d | 884 | struct lockdep_subclass_key *key; |
a63f38cc | 885 | struct hlist_head *hash_head; |
8e18257d | 886 | struct lock_class *class; |
fbb9ce95 | 887 | |
4ba053c0 | 888 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
49faa777 | 889 | instrumentation_begin(); |
4ba053c0 HM |
890 | debug_locks_off(); |
891 | printk(KERN_ERR | |
892 | "BUG: looking up invalid subclass: %u\n", subclass); | |
893 | printk(KERN_ERR | |
894 | "turning off the locking correctness validator.\n"); | |
895 | dump_stack(); | |
49faa777 | 896 | instrumentation_end(); |
4ba053c0 HM |
897 | return NULL; |
898 | } | |
899 | ||
8e18257d | 900 | /* |
64f29d1b MW |
901 | * If it is not initialised then it has never been locked, |
902 | * so it won't be present in the hash table. | |
8e18257d | 903 | */ |
64f29d1b MW |
904 | if (unlikely(!lock->key)) |
905 | return NULL; | |
fbb9ce95 | 906 | |
8e18257d PZ |
907 | /* |
908 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
909 | * lock_class_key variable is passed in through the mutex_init() | |
910 | * (or spin_lock_init()) call - which acts as the key. For static | |
911 | * locks we use the lock object itself as the key. | |
912 | */ | |
4b32d0a4 PZ |
913 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
914 | sizeof(struct lockdep_map)); | |
fbb9ce95 | 915 | |
8e18257d | 916 | key = lock->key->subkeys + subclass; |
ca268c69 | 917 | |
8e18257d | 918 | hash_head = classhashentry(key); |
74c383f1 | 919 | |
8e18257d | 920 | /* |
35a9393c | 921 | * We do an RCU walk of the hash, see lockdep_free_key_range(). |
8e18257d | 922 | */ |
35a9393c PZ |
923 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
924 | return NULL; | |
925 | ||
ce0b9c80 | 926 | hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) { |
4b32d0a4 | 927 | if (class->key == key) { |
0119fee4 PZ |
928 | /* |
929 | * Huh! same key, different name? Did someone trample | |
930 | * on some memory? We're most confused. | |
931 | */ | |
76e64c73 TH |
932 | WARN_ONCE(class->name != lock->name && |
933 | lock->key != &__lockdep_no_validate__, | |
934 | "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n", | |
935 | lock->name, lock->key, class->name); | |
8e18257d | 936 | return class; |
4b32d0a4 PZ |
937 | } |
938 | } | |
fbb9ce95 | 939 | |
64f29d1b MW |
940 | return NULL; |
941 | } | |
942 | ||
943 | /* | |
944 | * Static locks do not have their class-keys yet - for them the key is | |
945 | * the lock object itself. If the lock is in the per cpu area, the | |
946 | * canonical address of the lock (per cpu offset removed) is used. | |
947 | */ | |
948 | static bool assign_lock_key(struct lockdep_map *lock) | |
949 | { | |
950 | unsigned long can_addr, addr = (unsigned long)lock; | |
951 | ||
4bf50862 BVA |
952 | #ifdef __KERNEL__ |
953 | /* | |
954 | * lockdep_free_key_range() assumes that struct lock_class_key | |
955 | * objects do not overlap. Since we use the address of lock | |
956 | * objects as class key for static objects, check whether the | |
957 | * size of lock_class_key objects does not exceed the size of | |
958 | * the smallest lock object. | |
959 | */ | |
960 | BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t)); | |
961 | #endif | |
962 | ||
64f29d1b MW |
963 | if (__is_kernel_percpu_address(addr, &can_addr)) |
964 | lock->key = (void *)can_addr; | |
965 | else if (__is_module_percpu_address(addr, &can_addr)) | |
966 | lock->key = (void *)can_addr; | |
967 | else if (static_obj(lock)) | |
968 | lock->key = (void *)lock; | |
969 | else { | |
970 | /* Debug-check: all keys must be persistent! */ | |
971 | debug_locks_off(); | |
972 | pr_err("INFO: trying to register non-static key.\n"); | |
3a85969e TH |
973 | pr_err("The code is fine but needs lockdep annotation, or maybe\n"); |
974 | pr_err("you didn't initialize this object before use?\n"); | |
64f29d1b MW |
975 | pr_err("turning off the locking correctness validator.\n"); |
976 | dump_stack(); | |
977 | return false; | |
978 | } | |
979 | ||
980 | return true; | |
fbb9ce95 IM |
981 | } |
982 | ||
72dcd505 PZ |
983 | #ifdef CONFIG_DEBUG_LOCKDEP |
984 | ||
b526b2e3 BVA |
985 | /* Check whether element @e occurs in list @h */ |
986 | static bool in_list(struct list_head *e, struct list_head *h) | |
987 | { | |
988 | struct list_head *f; | |
989 | ||
990 | list_for_each(f, h) { | |
991 | if (e == f) | |
992 | return true; | |
993 | } | |
994 | ||
995 | return false; | |
996 | } | |
997 | ||
998 | /* | |
999 | * Check whether entry @e occurs in any of the locks_after or locks_before | |
1000 | * lists. | |
1001 | */ | |
1002 | static bool in_any_class_list(struct list_head *e) | |
1003 | { | |
1004 | struct lock_class *class; | |
1005 | int i; | |
1006 | ||
1007 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { | |
1008 | class = &lock_classes[i]; | |
1009 | if (in_list(e, &class->locks_after) || | |
1010 | in_list(e, &class->locks_before)) | |
1011 | return true; | |
1012 | } | |
1013 | return false; | |
1014 | } | |
1015 | ||
1016 | static bool class_lock_list_valid(struct lock_class *c, struct list_head *h) | |
1017 | { | |
1018 | struct lock_list *e; | |
1019 | ||
1020 | list_for_each_entry(e, h, entry) { | |
1021 | if (e->links_to != c) { | |
1022 | printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s", | |
1023 | c->name ? : "(?)", | |
1024 | (unsigned long)(e - list_entries), | |
1025 | e->links_to && e->links_to->name ? | |
1026 | e->links_to->name : "(?)", | |
1027 | e->class && e->class->name ? e->class->name : | |
1028 | "(?)"); | |
1029 | return false; | |
1030 | } | |
1031 | } | |
1032 | return true; | |
1033 | } | |
1034 | ||
3fe7522f AB |
1035 | #ifdef CONFIG_PROVE_LOCKING |
1036 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; | |
1037 | #endif | |
b526b2e3 BVA |
1038 | |
1039 | static bool check_lock_chain_key(struct lock_chain *chain) | |
1040 | { | |
1041 | #ifdef CONFIG_PROVE_LOCKING | |
f6ec8829 | 1042 | u64 chain_key = INITIAL_CHAIN_KEY; |
b526b2e3 BVA |
1043 | int i; |
1044 | ||
1045 | for (i = chain->base; i < chain->base + chain->depth; i++) | |
01bb6f0a | 1046 | chain_key = iterate_chain_key(chain_key, chain_hlocks[i]); |
b526b2e3 BVA |
1047 | /* |
1048 | * The 'unsigned long long' casts avoid that a compiler warning | |
1049 | * is reported when building tools/lib/lockdep. | |
1050 | */ | |
72dcd505 | 1051 | if (chain->chain_key != chain_key) { |
b526b2e3 BVA |
1052 | printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n", |
1053 | (unsigned long long)(chain - lock_chains), | |
1054 | (unsigned long long)chain->chain_key, | |
1055 | (unsigned long long)chain_key); | |
72dcd505 PZ |
1056 | return false; |
1057 | } | |
b526b2e3 | 1058 | #endif |
72dcd505 | 1059 | return true; |
b526b2e3 BVA |
1060 | } |
1061 | ||
1062 | static bool in_any_zapped_class_list(struct lock_class *class) | |
1063 | { | |
1064 | struct pending_free *pf; | |
1065 | int i; | |
1066 | ||
72dcd505 | 1067 | for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) { |
b526b2e3 BVA |
1068 | if (in_list(&class->lock_entry, &pf->zapped)) |
1069 | return true; | |
72dcd505 | 1070 | } |
b526b2e3 BVA |
1071 | |
1072 | return false; | |
1073 | } | |
1074 | ||
72dcd505 | 1075 | static bool __check_data_structures(void) |
b526b2e3 BVA |
1076 | { |
1077 | struct lock_class *class; | |
1078 | struct lock_chain *chain; | |
1079 | struct hlist_head *head; | |
1080 | struct lock_list *e; | |
1081 | int i; | |
1082 | ||
1083 | /* Check whether all classes occur in a lock list. */ | |
1084 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { | |
1085 | class = &lock_classes[i]; | |
1086 | if (!in_list(&class->lock_entry, &all_lock_classes) && | |
1087 | !in_list(&class->lock_entry, &free_lock_classes) && | |
1088 | !in_any_zapped_class_list(class)) { | |
1089 | printk(KERN_INFO "class %px/%s is not in any class list\n", | |
1090 | class, class->name ? : "(?)"); | |
1091 | return false; | |
b526b2e3 BVA |
1092 | } |
1093 | } | |
1094 | ||
1095 | /* Check whether all classes have valid lock lists. */ | |
1096 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { | |
1097 | class = &lock_classes[i]; | |
1098 | if (!class_lock_list_valid(class, &class->locks_before)) | |
1099 | return false; | |
1100 | if (!class_lock_list_valid(class, &class->locks_after)) | |
1101 | return false; | |
1102 | } | |
1103 | ||
1104 | /* Check the chain_key of all lock chains. */ | |
1105 | for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { | |
1106 | head = chainhash_table + i; | |
1107 | hlist_for_each_entry_rcu(chain, head, entry) { | |
1108 | if (!check_lock_chain_key(chain)) | |
1109 | return false; | |
1110 | } | |
1111 | } | |
1112 | ||
1113 | /* | |
1114 | * Check whether all list entries that are in use occur in a class | |
1115 | * lock list. | |
1116 | */ | |
1117 | for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { | |
1118 | e = list_entries + i; | |
1119 | if (!in_any_class_list(&e->entry)) { | |
1120 | printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n", | |
1121 | (unsigned int)(e - list_entries), | |
1122 | e->class->name ? : "(?)", | |
1123 | e->links_to->name ? : "(?)"); | |
1124 | return false; | |
1125 | } | |
1126 | } | |
1127 | ||
1128 | /* | |
1129 | * Check whether all list entries that are not in use do not occur in | |
1130 | * a class lock list. | |
1131 | */ | |
1132 | for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { | |
1133 | e = list_entries + i; | |
1134 | if (in_any_class_list(&e->entry)) { | |
1135 | printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n", | |
1136 | (unsigned int)(e - list_entries), | |
1137 | e->class && e->class->name ? e->class->name : | |
1138 | "(?)", | |
1139 | e->links_to && e->links_to->name ? | |
1140 | e->links_to->name : "(?)"); | |
1141 | return false; | |
1142 | } | |
1143 | } | |
1144 | ||
1145 | return true; | |
1146 | } | |
1147 | ||
72dcd505 PZ |
1148 | int check_consistency = 0; |
1149 | module_param(check_consistency, int, 0644); | |
1150 | ||
1151 | static void check_data_structures(void) | |
1152 | { | |
1153 | static bool once = false; | |
1154 | ||
1155 | if (check_consistency && !once) { | |
1156 | if (!__check_data_structures()) { | |
1157 | once = true; | |
1158 | WARN_ON(once); | |
1159 | } | |
1160 | } | |
1161 | } | |
1162 | ||
1163 | #else /* CONFIG_DEBUG_LOCKDEP */ | |
1164 | ||
1165 | static inline void check_data_structures(void) { } | |
1166 | ||
1167 | #endif /* CONFIG_DEBUG_LOCKDEP */ | |
1168 | ||
810507fe WL |
1169 | static void init_chain_block_buckets(void); |
1170 | ||
feb0a386 | 1171 | /* |
a0b0fd53 BVA |
1172 | * Initialize the lock_classes[] array elements, the free_lock_classes list |
1173 | * and also the delayed_free structure. | |
feb0a386 BVA |
1174 | */ |
1175 | static void init_data_structures_once(void) | |
1176 | { | |
810507fe | 1177 | static bool __read_mostly ds_initialized, rcu_head_initialized; |
feb0a386 BVA |
1178 | int i; |
1179 | ||
0126574f | 1180 | if (likely(rcu_head_initialized)) |
feb0a386 BVA |
1181 | return; |
1182 | ||
0126574f BVA |
1183 | if (system_state >= SYSTEM_SCHEDULING) { |
1184 | init_rcu_head(&delayed_free.rcu_head); | |
1185 | rcu_head_initialized = true; | |
1186 | } | |
1187 | ||
1188 | if (ds_initialized) | |
1189 | return; | |
1190 | ||
1191 | ds_initialized = true; | |
feb0a386 | 1192 | |
a0b0fd53 BVA |
1193 | INIT_LIST_HEAD(&delayed_free.pf[0].zapped); |
1194 | INIT_LIST_HEAD(&delayed_free.pf[1].zapped); | |
1195 | ||
feb0a386 | 1196 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { |
a0b0fd53 | 1197 | list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes); |
feb0a386 BVA |
1198 | INIT_LIST_HEAD(&lock_classes[i].locks_after); |
1199 | INIT_LIST_HEAD(&lock_classes[i].locks_before); | |
1200 | } | |
810507fe | 1201 | init_chain_block_buckets(); |
feb0a386 BVA |
1202 | } |
1203 | ||
108c1485 BVA |
1204 | static inline struct hlist_head *keyhashentry(const struct lock_class_key *key) |
1205 | { | |
1206 | unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS); | |
1207 | ||
1208 | return lock_keys_hash + hash; | |
1209 | } | |
1210 | ||
1211 | /* Register a dynamically allocated key. */ | |
1212 | void lockdep_register_key(struct lock_class_key *key) | |
1213 | { | |
1214 | struct hlist_head *hash_head; | |
1215 | struct lock_class_key *k; | |
1216 | unsigned long flags; | |
1217 | ||
1218 | if (WARN_ON_ONCE(static_obj(key))) | |
1219 | return; | |
1220 | hash_head = keyhashentry(key); | |
1221 | ||
1222 | raw_local_irq_save(flags); | |
1223 | if (!graph_lock()) | |
1224 | goto restore_irqs; | |
1225 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { | |
1226 | if (WARN_ON_ONCE(k == key)) | |
1227 | goto out_unlock; | |
1228 | } | |
1229 | hlist_add_head_rcu(&key->hash_entry, hash_head); | |
1230 | out_unlock: | |
1231 | graph_unlock(); | |
1232 | restore_irqs: | |
1233 | raw_local_irq_restore(flags); | |
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(lockdep_register_key); | |
1236 | ||
1237 | /* Check whether a key has been registered as a dynamic key. */ | |
1238 | static bool is_dynamic_key(const struct lock_class_key *key) | |
1239 | { | |
1240 | struct hlist_head *hash_head; | |
1241 | struct lock_class_key *k; | |
1242 | bool found = false; | |
1243 | ||
1244 | if (WARN_ON_ONCE(static_obj(key))) | |
1245 | return false; | |
1246 | ||
1247 | /* | |
1248 | * If lock debugging is disabled lock_keys_hash[] may contain | |
1249 | * pointers to memory that has already been freed. Avoid triggering | |
1250 | * a use-after-free in that case by returning early. | |
1251 | */ | |
1252 | if (!debug_locks) | |
1253 | return true; | |
1254 | ||
1255 | hash_head = keyhashentry(key); | |
1256 | ||
1257 | rcu_read_lock(); | |
1258 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { | |
1259 | if (k == key) { | |
1260 | found = true; | |
1261 | break; | |
1262 | } | |
1263 | } | |
1264 | rcu_read_unlock(); | |
1265 | ||
1266 | return found; | |
1267 | } | |
1268 | ||
fbb9ce95 | 1269 | /* |
8e18257d PZ |
1270 | * Register a lock's class in the hash-table, if the class is not present |
1271 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1272 | * itself, so actual lookup of the hash should be once per lock object. | |
fbb9ce95 | 1273 | */ |
c003ed92 | 1274 | static struct lock_class * |
8e18257d | 1275 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
fbb9ce95 | 1276 | { |
8e18257d | 1277 | struct lockdep_subclass_key *key; |
a63f38cc | 1278 | struct hlist_head *hash_head; |
8e18257d | 1279 | struct lock_class *class; |
fb7275ac | 1280 | int idx; |
35a9393c PZ |
1281 | |
1282 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
8e18257d PZ |
1283 | |
1284 | class = look_up_lock_class(lock, subclass); | |
64f29d1b | 1285 | if (likely(class)) |
87cdee71 | 1286 | goto out_set_class_cache; |
8e18257d | 1287 | |
64f29d1b MW |
1288 | if (!lock->key) { |
1289 | if (!assign_lock_key(lock)) | |
1290 | return NULL; | |
108c1485 | 1291 | } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) { |
8e18257d PZ |
1292 | return NULL; |
1293 | } | |
1294 | ||
1295 | key = lock->key->subkeys + subclass; | |
1296 | hash_head = classhashentry(key); | |
1297 | ||
8e18257d | 1298 | if (!graph_lock()) { |
8e18257d PZ |
1299 | return NULL; |
1300 | } | |
1301 | /* | |
1302 | * We have to do the hash-walk again, to avoid races | |
1303 | * with another CPU: | |
1304 | */ | |
a63f38cc | 1305 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { |
8e18257d PZ |
1306 | if (class->key == key) |
1307 | goto out_unlock_set; | |
35a9393c PZ |
1308 | } |
1309 | ||
feb0a386 BVA |
1310 | init_data_structures_once(); |
1311 | ||
a0b0fd53 BVA |
1312 | /* Allocate a new lock class and add it to the hash. */ |
1313 | class = list_first_entry_or_null(&free_lock_classes, typeof(*class), | |
1314 | lock_entry); | |
1315 | if (!class) { | |
8e18257d | 1316 | if (!debug_locks_off_graph_unlock()) { |
8e18257d PZ |
1317 | return NULL; |
1318 | } | |
8e18257d | 1319 | |
2c522836 | 1320 | print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); |
eedeeabd | 1321 | dump_stack(); |
8e18257d PZ |
1322 | return NULL; |
1323 | } | |
a0b0fd53 | 1324 | nr_lock_classes++; |
01bb6f0a | 1325 | __set_bit(class - lock_classes, lock_classes_in_use); |
bd6d29c2 | 1326 | debug_atomic_inc(nr_unused_locks); |
8e18257d PZ |
1327 | class->key = key; |
1328 | class->name = lock->name; | |
1329 | class->subclass = subclass; | |
feb0a386 BVA |
1330 | WARN_ON_ONCE(!list_empty(&class->locks_before)); |
1331 | WARN_ON_ONCE(!list_empty(&class->locks_after)); | |
8e18257d | 1332 | class->name_version = count_matching_names(class); |
de8f5e4f PZ |
1333 | class->wait_type_inner = lock->wait_type_inner; |
1334 | class->wait_type_outer = lock->wait_type_outer; | |
dfd5e3f5 | 1335 | class->lock_type = lock->lock_type; |
8e18257d PZ |
1336 | /* |
1337 | * We use RCU's safe list-add method to make | |
1338 | * parallel walking of the hash-list safe: | |
1339 | */ | |
a63f38cc | 1340 | hlist_add_head_rcu(&class->hash_entry, hash_head); |
1481197b | 1341 | /* |
a0b0fd53 BVA |
1342 | * Remove the class from the free list and add it to the global list |
1343 | * of classes. | |
1481197b | 1344 | */ |
a0b0fd53 | 1345 | list_move_tail(&class->lock_entry, &all_lock_classes); |
fb7275ac WL |
1346 | idx = class - lock_classes; |
1347 | if (idx > max_lock_class_idx) | |
1348 | max_lock_class_idx = idx; | |
8e18257d PZ |
1349 | |
1350 | if (verbose(class)) { | |
1351 | graph_unlock(); | |
8e18257d | 1352 | |
04860d48 | 1353 | printk("\nnew class %px: %s", class->key, class->name); |
8e18257d | 1354 | if (class->name_version > 1) |
f943fe0f DV |
1355 | printk(KERN_CONT "#%d", class->name_version); |
1356 | printk(KERN_CONT "\n"); | |
8e18257d PZ |
1357 | dump_stack(); |
1358 | ||
8e18257d | 1359 | if (!graph_lock()) { |
8e18257d PZ |
1360 | return NULL; |
1361 | } | |
1362 | } | |
1363 | out_unlock_set: | |
1364 | graph_unlock(); | |
8e18257d | 1365 | |
87cdee71 | 1366 | out_set_class_cache: |
8e18257d | 1367 | if (!subclass || force) |
62016250 HM |
1368 | lock->class_cache[0] = class; |
1369 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) | |
1370 | lock->class_cache[subclass] = class; | |
8e18257d | 1371 | |
0119fee4 PZ |
1372 | /* |
1373 | * Hash collision, did we smoke some? We found a class with a matching | |
1374 | * hash but the subclass -- which is hashed in -- didn't match. | |
1375 | */ | |
8e18257d PZ |
1376 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
1377 | return NULL; | |
1378 | ||
1379 | return class; | |
1380 | } | |
1381 | ||
1382 | #ifdef CONFIG_PROVE_LOCKING | |
1383 | /* | |
1384 | * Allocate a lockdep entry. (assumes the graph_lock held, returns | |
1385 | * with NULL on failure) | |
1386 | */ | |
1387 | static struct lock_list *alloc_list_entry(void) | |
1388 | { | |
ace35a7a BVA |
1389 | int idx = find_first_zero_bit(list_entries_in_use, |
1390 | ARRAY_SIZE(list_entries)); | |
1391 | ||
1392 | if (idx >= ARRAY_SIZE(list_entries)) { | |
8e18257d PZ |
1393 | if (!debug_locks_off_graph_unlock()) |
1394 | return NULL; | |
1395 | ||
2c522836 | 1396 | print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); |
eedeeabd | 1397 | dump_stack(); |
8e18257d PZ |
1398 | return NULL; |
1399 | } | |
ace35a7a BVA |
1400 | nr_list_entries++; |
1401 | __set_bit(idx, list_entries_in_use); | |
1402 | return list_entries + idx; | |
8e18257d PZ |
1403 | } |
1404 | ||
1405 | /* | |
1406 | * Add a new dependency to the head of the list: | |
1407 | */ | |
86cffb80 BVA |
1408 | static int add_lock_to_list(struct lock_class *this, |
1409 | struct lock_class *links_to, struct list_head *head, | |
8b023acc | 1410 | u16 distance, u8 dep, |
12593b74 | 1411 | const struct lock_trace *trace) |
8e18257d PZ |
1412 | { |
1413 | struct lock_list *entry; | |
1414 | /* | |
1415 | * Lock not present yet - get a new dependency struct and | |
1416 | * add it to the list: | |
1417 | */ | |
1418 | entry = alloc_list_entry(); | |
1419 | if (!entry) | |
1420 | return 0; | |
1421 | ||
74870172 | 1422 | entry->class = this; |
86cffb80 | 1423 | entry->links_to = links_to; |
3454a36d | 1424 | entry->dep = dep; |
74870172 | 1425 | entry->distance = distance; |
12593b74 | 1426 | entry->trace = trace; |
8e18257d | 1427 | /* |
35a9393c PZ |
1428 | * Both allocation and removal are done under the graph lock; but |
1429 | * iteration is under RCU-sched; see look_up_lock_class() and | |
1430 | * lockdep_free_key_range(). | |
8e18257d PZ |
1431 | */ |
1432 | list_add_tail_rcu(&entry->entry, head); | |
1433 | ||
1434 | return 1; | |
1435 | } | |
1436 | ||
98c33edd PZ |
1437 | /* |
1438 | * For good efficiency of modular, we use power of 2 | |
1439 | */ | |
5dc33592 | 1440 | #define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS) |
af012961 PZ |
1441 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
1442 | ||
98c33edd | 1443 | /* |
aa480771 YD |
1444 | * The circular_queue and helpers are used to implement graph |
1445 | * breadth-first search (BFS) algorithm, by which we can determine | |
1446 | * whether there is a path from a lock to another. In deadlock checks, | |
1447 | * a path from the next lock to be acquired to a previous held lock | |
1448 | * indicates that adding the <prev> -> <next> lock dependency will | |
1449 | * produce a circle in the graph. Breadth-first search instead of | |
1450 | * depth-first search is used in order to find the shortest (circular) | |
1451 | * path. | |
98c33edd | 1452 | */ |
af012961 | 1453 | struct circular_queue { |
aa480771 | 1454 | struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE]; |
af012961 PZ |
1455 | unsigned int front, rear; |
1456 | }; | |
1457 | ||
1458 | static struct circular_queue lock_cq; | |
af012961 | 1459 | |
12f3dfd0 | 1460 | unsigned int max_bfs_queue_depth; |
af012961 | 1461 | |
e351b660 ML |
1462 | static unsigned int lockdep_dependency_gen_id; |
1463 | ||
af012961 PZ |
1464 | static inline void __cq_init(struct circular_queue *cq) |
1465 | { | |
1466 | cq->front = cq->rear = 0; | |
e351b660 | 1467 | lockdep_dependency_gen_id++; |
af012961 PZ |
1468 | } |
1469 | ||
1470 | static inline int __cq_empty(struct circular_queue *cq) | |
1471 | { | |
1472 | return (cq->front == cq->rear); | |
1473 | } | |
1474 | ||
1475 | static inline int __cq_full(struct circular_queue *cq) | |
1476 | { | |
1477 | return ((cq->rear + 1) & CQ_MASK) == cq->front; | |
1478 | } | |
1479 | ||
aa480771 | 1480 | static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem) |
af012961 PZ |
1481 | { |
1482 | if (__cq_full(cq)) | |
1483 | return -1; | |
1484 | ||
1485 | cq->element[cq->rear] = elem; | |
1486 | cq->rear = (cq->rear + 1) & CQ_MASK; | |
1487 | return 0; | |
1488 | } | |
1489 | ||
c1661325 YD |
1490 | /* |
1491 | * Dequeue an element from the circular_queue, return a lock_list if | |
1492 | * the queue is not empty, or NULL if otherwise. | |
1493 | */ | |
1494 | static inline struct lock_list * __cq_dequeue(struct circular_queue *cq) | |
af012961 | 1495 | { |
c1661325 YD |
1496 | struct lock_list * lock; |
1497 | ||
af012961 | 1498 | if (__cq_empty(cq)) |
c1661325 | 1499 | return NULL; |
af012961 | 1500 | |
c1661325 | 1501 | lock = cq->element[cq->front]; |
af012961 | 1502 | cq->front = (cq->front + 1) & CQ_MASK; |
c1661325 YD |
1503 | |
1504 | return lock; | |
af012961 PZ |
1505 | } |
1506 | ||
1507 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) | |
1508 | { | |
1509 | return (cq->rear - cq->front) & CQ_MASK; | |
1510 | } | |
1511 | ||
d563bc6e | 1512 | static inline void mark_lock_accessed(struct lock_list *lock) |
af012961 | 1513 | { |
d563bc6e BF |
1514 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
1515 | } | |
98c33edd | 1516 | |
d563bc6e BF |
1517 | static inline void visit_lock_entry(struct lock_list *lock, |
1518 | struct lock_list *parent) | |
1519 | { | |
af012961 | 1520 | lock->parent = parent; |
af012961 PZ |
1521 | } |
1522 | ||
1523 | static inline unsigned long lock_accessed(struct lock_list *lock) | |
1524 | { | |
e351b660 | 1525 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
af012961 PZ |
1526 | } |
1527 | ||
1528 | static inline struct lock_list *get_lock_parent(struct lock_list *child) | |
1529 | { | |
1530 | return child->parent; | |
1531 | } | |
1532 | ||
1533 | static inline int get_lock_depth(struct lock_list *child) | |
1534 | { | |
1535 | int depth = 0; | |
1536 | struct lock_list *parent; | |
1537 | ||
1538 | while ((parent = get_lock_parent(child))) { | |
1539 | child = parent; | |
1540 | depth++; | |
1541 | } | |
1542 | return depth; | |
1543 | } | |
1544 | ||
77a80692 YD |
1545 | /* |
1546 | * Return the forward or backward dependency list. | |
1547 | * | |
1548 | * @lock: the lock_list to get its class's dependency list | |
1549 | * @offset: the offset to struct lock_class to determine whether it is | |
1550 | * locks_after or locks_before | |
1551 | */ | |
1552 | static inline struct list_head *get_dep_list(struct lock_list *lock, int offset) | |
1553 | { | |
1554 | void *lock_class = lock->class; | |
1555 | ||
1556 | return lock_class + offset; | |
1557 | } | |
b11be024 BF |
1558 | /* |
1559 | * Return values of a bfs search: | |
1560 | * | |
1561 | * BFS_E* indicates an error | |
1562 | * BFS_R* indicates a result (match or not) | |
1563 | * | |
1564 | * BFS_EINVALIDNODE: Find a invalid node in the graph. | |
1565 | * | |
1566 | * BFS_EQUEUEFULL: The queue is full while doing the bfs. | |
1567 | * | |
1568 | * BFS_RMATCH: Find the matched node in the graph, and put that node into | |
1569 | * *@target_entry. | |
1570 | * | |
1571 | * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry | |
1572 | * _unchanged_. | |
1573 | */ | |
1574 | enum bfs_result { | |
1575 | BFS_EINVALIDNODE = -2, | |
1576 | BFS_EQUEUEFULL = -1, | |
1577 | BFS_RMATCH = 0, | |
1578 | BFS_RNOMATCH = 1, | |
1579 | }; | |
1580 | ||
1581 | /* | |
1582 | * bfs_result < 0 means error | |
1583 | */ | |
1584 | static inline bool bfs_error(enum bfs_result res) | |
1585 | { | |
1586 | return res < 0; | |
1587 | } | |
77a80692 | 1588 | |
3454a36d BF |
1589 | /* |
1590 | * DEP_*_BIT in lock_list::dep | |
1591 | * | |
1592 | * For dependency @prev -> @next: | |
1593 | * | |
1594 | * SR: @prev is shared reader (->read != 0) and @next is recursive reader | |
1595 | * (->read == 2) | |
1596 | * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader | |
1597 | * SN: @prev is shared reader and @next is non-recursive locker (->read != 2) | |
1598 | * EN: @prev is exclusive locker and @next is non-recursive locker | |
1599 | * | |
1600 | * Note that we define the value of DEP_*_BITs so that: | |
1601 | * bit0 is prev->read == 0 | |
1602 | * bit1 is next->read != 2 | |
1603 | */ | |
1604 | #define DEP_SR_BIT (0 + (0 << 1)) /* 0 */ | |
1605 | #define DEP_ER_BIT (1 + (0 << 1)) /* 1 */ | |
1606 | #define DEP_SN_BIT (0 + (1 << 1)) /* 2 */ | |
1607 | #define DEP_EN_BIT (1 + (1 << 1)) /* 3 */ | |
1608 | ||
1609 | #define DEP_SR_MASK (1U << (DEP_SR_BIT)) | |
1610 | #define DEP_ER_MASK (1U << (DEP_ER_BIT)) | |
1611 | #define DEP_SN_MASK (1U << (DEP_SN_BIT)) | |
1612 | #define DEP_EN_MASK (1U << (DEP_EN_BIT)) | |
1613 | ||
1614 | static inline unsigned int | |
1615 | __calc_dep_bit(struct held_lock *prev, struct held_lock *next) | |
1616 | { | |
1617 | return (prev->read == 0) + ((next->read != 2) << 1); | |
1618 | } | |
1619 | ||
1620 | static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next) | |
1621 | { | |
1622 | return 1U << __calc_dep_bit(prev, next); | |
1623 | } | |
1624 | ||
1625 | /* | |
1626 | * calculate the dep_bit for backwards edges. We care about whether @prev is | |
1627 | * shared and whether @next is recursive. | |
1628 | */ | |
1629 | static inline unsigned int | |
1630 | __calc_dep_bitb(struct held_lock *prev, struct held_lock *next) | |
1631 | { | |
1632 | return (next->read != 2) + ((prev->read == 0) << 1); | |
1633 | } | |
1634 | ||
1635 | static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next) | |
1636 | { | |
1637 | return 1U << __calc_dep_bitb(prev, next); | |
1638 | } | |
1639 | ||
154f185e | 1640 | /* |
6971c0f3 BF |
1641 | * Initialize a lock_list entry @lock belonging to @class as the root for a BFS |
1642 | * search. | |
1643 | */ | |
1644 | static inline void __bfs_init_root(struct lock_list *lock, | |
1645 | struct lock_class *class) | |
1646 | { | |
1647 | lock->class = class; | |
1648 | lock->parent = NULL; | |
1649 | lock->only_xr = 0; | |
1650 | } | |
1651 | ||
1652 | /* | |
1653 | * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the | |
1654 | * root for a BFS search. | |
1655 | * | |
1656 | * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure | |
1657 | * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)-> | |
1658 | * and -(S*)->. | |
1659 | */ | |
1660 | static inline void bfs_init_root(struct lock_list *lock, | |
1661 | struct held_lock *hlock) | |
1662 | { | |
1663 | __bfs_init_root(lock, hlock_class(hlock)); | |
1664 | lock->only_xr = (hlock->read == 2); | |
1665 | } | |
1666 | ||
1667 | /* | |
1668 | * Similar to bfs_init_root() but initialize the root for backwards BFS. | |
1669 | * | |
1670 | * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure | |
1671 | * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not | |
1672 | * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->). | |
1673 | */ | |
1674 | static inline void bfs_init_rootb(struct lock_list *lock, | |
1675 | struct held_lock *hlock) | |
1676 | { | |
1677 | __bfs_init_root(lock, hlock_class(hlock)); | |
1678 | lock->only_xr = (hlock->read != 0); | |
1679 | } | |
1680 | ||
6d1823cc BF |
1681 | static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset) |
1682 | { | |
1683 | if (!lock || !lock->parent) | |
1684 | return NULL; | |
1685 | ||
1686 | return list_next_or_null_rcu(get_dep_list(lock->parent, offset), | |
1687 | &lock->entry, struct lock_list, entry); | |
1688 | } | |
1689 | ||
6971c0f3 BF |
1690 | /* |
1691 | * Breadth-First Search to find a strong path in the dependency graph. | |
1692 | * | |
1693 | * @source_entry: the source of the path we are searching for. | |
1694 | * @data: data used for the second parameter of @match function | |
1695 | * @match: match function for the search | |
1696 | * @target_entry: pointer to the target of a matched path | |
1697 | * @offset: the offset to struct lock_class to determine whether it is | |
1698 | * locks_after or locks_before | |
1699 | * | |
1700 | * We may have multiple edges (considering different kinds of dependencies, | |
1701 | * e.g. ER and SN) between two nodes in the dependency graph. But | |
1702 | * only the strong dependency path in the graph is relevant to deadlocks. A | |
1703 | * strong dependency path is a dependency path that doesn't have two adjacent | |
1704 | * dependencies as -(*R)-> -(S*)->, please see: | |
1705 | * | |
1706 | * Documentation/locking/lockdep-design.rst | |
1707 | * | |
1708 | * for more explanation of the definition of strong dependency paths | |
1709 | * | |
1710 | * In __bfs(), we only traverse in the strong dependency path: | |
1711 | * | |
1712 | * In lock_list::only_xr, we record whether the previous dependency only | |
1713 | * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we | |
1714 | * filter out any -(S*)-> in the current dependency and after that, the | |
1715 | * ->only_xr is set according to whether we only have -(*R)-> left. | |
154f185e | 1716 | */ |
b11be024 BF |
1717 | static enum bfs_result __bfs(struct lock_list *source_entry, |
1718 | void *data, | |
61775ed2 | 1719 | bool (*match)(struct lock_list *entry, void *data), |
bc2dd71b | 1720 | bool (*skip)(struct lock_list *entry, void *data), |
b11be024 BF |
1721 | struct lock_list **target_entry, |
1722 | int offset) | |
c94aa5ca | 1723 | { |
6d1823cc BF |
1724 | struct circular_queue *cq = &lock_cq; |
1725 | struct lock_list *lock = NULL; | |
c94aa5ca | 1726 | struct lock_list *entry; |
d588e461 | 1727 | struct list_head *head; |
6d1823cc BF |
1728 | unsigned int cq_depth; |
1729 | bool first; | |
c94aa5ca | 1730 | |
248efb21 PZ |
1731 | lockdep_assert_locked(); |
1732 | ||
d588e461 | 1733 | __cq_init(cq); |
aa480771 | 1734 | __cq_enqueue(cq, source_entry); |
c94aa5ca | 1735 | |
6d1823cc BF |
1736 | while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) { |
1737 | if (!lock->class) | |
1738 | return BFS_EINVALIDNODE; | |
c94aa5ca | 1739 | |
d563bc6e | 1740 | /* |
6d1823cc BF |
1741 | * Step 1: check whether we already finish on this one. |
1742 | * | |
d563bc6e BF |
1743 | * If we have visited all the dependencies from this @lock to |
1744 | * others (iow, if we have visited all lock_list entries in | |
1745 | * @lock->class->locks_{after,before}) we skip, otherwise go | |
1746 | * and visit all the dependencies in the list and mark this | |
1747 | * list accessed. | |
1748 | */ | |
1749 | if (lock_accessed(lock)) | |
1750 | continue; | |
1751 | else | |
1752 | mark_lock_accessed(lock); | |
1753 | ||
6d1823cc BF |
1754 | /* |
1755 | * Step 2: check whether prev dependency and this form a strong | |
1756 | * dependency path. | |
1757 | */ | |
1758 | if (lock->parent) { /* Parent exists, check prev dependency */ | |
1759 | u8 dep = lock->dep; | |
1760 | bool prev_only_xr = lock->parent->only_xr; | |
6971c0f3 BF |
1761 | |
1762 | /* | |
1763 | * Mask out all -(S*)-> if we only have *R in previous | |
1764 | * step, because -(*R)-> -(S*)-> don't make up a strong | |
1765 | * dependency. | |
1766 | */ | |
1767 | if (prev_only_xr) | |
1768 | dep &= ~(DEP_SR_MASK | DEP_SN_MASK); | |
1769 | ||
1770 | /* If nothing left, we skip */ | |
1771 | if (!dep) | |
1772 | continue; | |
1773 | ||
1774 | /* If there are only -(*R)-> left, set that for the next step */ | |
6d1823cc BF |
1775 | lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK)); |
1776 | } | |
1777 | ||
1778 | /* | |
1779 | * Step 3: we haven't visited this and there is a strong | |
1780 | * dependency path to this, so check with @match. | |
bc2dd71b BF |
1781 | * If @skip is provide and returns true, we skip this |
1782 | * lock (and any path this lock is in). | |
6d1823cc | 1783 | */ |
bc2dd71b BF |
1784 | if (skip && skip(lock, data)) |
1785 | continue; | |
1786 | ||
6d1823cc BF |
1787 | if (match(lock, data)) { |
1788 | *target_entry = lock; | |
1789 | return BFS_RMATCH; | |
1790 | } | |
d563bc6e | 1791 | |
6d1823cc BF |
1792 | /* |
1793 | * Step 4: if not match, expand the path by adding the | |
e2db7592 | 1794 | * forward or backwards dependencies in the search |
6d1823cc BF |
1795 | * |
1796 | */ | |
1797 | first = true; | |
1798 | head = get_dep_list(lock, offset); | |
1799 | list_for_each_entry_rcu(entry, head, entry) { | |
d563bc6e | 1800 | visit_lock_entry(entry, lock); |
6d1823cc BF |
1801 | |
1802 | /* | |
1803 | * Note we only enqueue the first of the list into the | |
1804 | * queue, because we can always find a sibling | |
1805 | * dependency from one (see __bfs_next()), as a result | |
1806 | * the space of queue is saved. | |
1807 | */ | |
1808 | if (!first) | |
1809 | continue; | |
1810 | ||
1811 | first = false; | |
1812 | ||
1813 | if (__cq_enqueue(cq, entry)) | |
1814 | return BFS_EQUEUEFULL; | |
1815 | ||
d563bc6e BF |
1816 | cq_depth = __cq_get_elem_count(cq); |
1817 | if (max_bfs_queue_depth < cq_depth) | |
1818 | max_bfs_queue_depth = cq_depth; | |
c94aa5ca ML |
1819 | } |
1820 | } | |
6d1823cc BF |
1821 | |
1822 | return BFS_RNOMATCH; | |
c94aa5ca ML |
1823 | } |
1824 | ||
b11be024 BF |
1825 | static inline enum bfs_result |
1826 | __bfs_forwards(struct lock_list *src_entry, | |
1827 | void *data, | |
61775ed2 | 1828 | bool (*match)(struct lock_list *entry, void *data), |
bc2dd71b | 1829 | bool (*skip)(struct lock_list *entry, void *data), |
b11be024 | 1830 | struct lock_list **target_entry) |
c94aa5ca | 1831 | { |
bc2dd71b | 1832 | return __bfs(src_entry, data, match, skip, target_entry, |
77a80692 | 1833 | offsetof(struct lock_class, locks_after)); |
c94aa5ca ML |
1834 | |
1835 | } | |
1836 | ||
b11be024 BF |
1837 | static inline enum bfs_result |
1838 | __bfs_backwards(struct lock_list *src_entry, | |
1839 | void *data, | |
61775ed2 | 1840 | bool (*match)(struct lock_list *entry, void *data), |
bc2dd71b | 1841 | bool (*skip)(struct lock_list *entry, void *data), |
b11be024 | 1842 | struct lock_list **target_entry) |
c94aa5ca | 1843 | { |
bc2dd71b | 1844 | return __bfs(src_entry, data, match, skip, target_entry, |
77a80692 | 1845 | offsetof(struct lock_class, locks_before)); |
c94aa5ca ML |
1846 | |
1847 | } | |
1848 | ||
12593b74 BVA |
1849 | static void print_lock_trace(const struct lock_trace *trace, |
1850 | unsigned int spaces) | |
c120bce7 | 1851 | { |
12593b74 | 1852 | stack_trace_print(trace->entries, trace->nr_entries, spaces); |
c120bce7 TG |
1853 | } |
1854 | ||
8e18257d PZ |
1855 | /* |
1856 | * Print a dependency chain entry (this is only done when a deadlock | |
1857 | * has been detected): | |
1858 | */ | |
f7c1c6b3 | 1859 | static noinline void |
24208ca7 | 1860 | print_circular_bug_entry(struct lock_list *target, int depth) |
8e18257d PZ |
1861 | { |
1862 | if (debug_locks_silent) | |
f7c1c6b3 | 1863 | return; |
8e18257d | 1864 | printk("\n-> #%u", depth); |
eb1cfd09 | 1865 | print_lock_name(NULL, target->class); |
f943fe0f | 1866 | printk(KERN_CONT ":\n"); |
12593b74 | 1867 | print_lock_trace(target->trace, 6); |
8e18257d PZ |
1868 | } |
1869 | ||
f4185812 SR |
1870 | static void |
1871 | print_circular_lock_scenario(struct held_lock *src, | |
1872 | struct held_lock *tgt, | |
1873 | struct lock_list *prt) | |
1874 | { | |
1875 | struct lock_class *source = hlock_class(src); | |
1876 | struct lock_class *target = hlock_class(tgt); | |
1877 | struct lock_class *parent = prt->class; | |
0471db44 BF |
1878 | int src_read = src->read; |
1879 | int tgt_read = tgt->read; | |
f4185812 SR |
1880 | |
1881 | /* | |
1882 | * A direct locking problem where unsafe_class lock is taken | |
1883 | * directly by safe_class lock, then all we need to show | |
1884 | * is the deadlock scenario, as it is obvious that the | |
1885 | * unsafe lock is taken under the safe lock. | |
1886 | * | |
1887 | * But if there is a chain instead, where the safe lock takes | |
1888 | * an intermediate lock (middle_class) where this lock is | |
1889 | * not the same as the safe lock, then the lock chain is | |
1890 | * used to describe the problem. Otherwise we would need | |
1891 | * to show a different CPU case for each link in the chain | |
1892 | * from the safe_class lock to the unsafe_class lock. | |
1893 | */ | |
1894 | if (parent != source) { | |
1895 | printk("Chain exists of:\n "); | |
eb1cfd09 | 1896 | __print_lock_name(src, source); |
f943fe0f | 1897 | printk(KERN_CONT " --> "); |
eb1cfd09 | 1898 | __print_lock_name(NULL, parent); |
f943fe0f | 1899 | printk(KERN_CONT " --> "); |
eb1cfd09 | 1900 | __print_lock_name(tgt, target); |
f943fe0f | 1901 | printk(KERN_CONT "\n\n"); |
f4185812 SR |
1902 | } |
1903 | ||
e966eaee IM |
1904 | printk(" Possible unsafe locking scenario:\n\n"); |
1905 | printk(" CPU0 CPU1\n"); | |
1906 | printk(" ---- ----\n"); | |
0471db44 BF |
1907 | if (tgt_read != 0) |
1908 | printk(" rlock("); | |
1909 | else | |
1910 | printk(" lock("); | |
eb1cfd09 | 1911 | __print_lock_name(tgt, target); |
e966eaee IM |
1912 | printk(KERN_CONT ");\n"); |
1913 | printk(" lock("); | |
eb1cfd09 | 1914 | __print_lock_name(NULL, parent); |
e966eaee IM |
1915 | printk(KERN_CONT ");\n"); |
1916 | printk(" lock("); | |
eb1cfd09 | 1917 | __print_lock_name(tgt, target); |
e966eaee | 1918 | printk(KERN_CONT ");\n"); |
0471db44 BF |
1919 | if (src_read != 0) |
1920 | printk(" rlock("); | |
1921 | else if (src->sync) | |
1922 | printk(" sync("); | |
1923 | else | |
1924 | printk(" lock("); | |
eb1cfd09 | 1925 | __print_lock_name(src, source); |
e966eaee IM |
1926 | printk(KERN_CONT ");\n"); |
1927 | printk("\n *** DEADLOCK ***\n\n"); | |
f4185812 SR |
1928 | } |
1929 | ||
8e18257d PZ |
1930 | /* |
1931 | * When a circular dependency is detected, print the | |
1932 | * header first: | |
1933 | */ | |
f7c1c6b3 | 1934 | static noinline void |
db0002a3 ML |
1935 | print_circular_bug_header(struct lock_list *entry, unsigned int depth, |
1936 | struct held_lock *check_src, | |
1937 | struct held_lock *check_tgt) | |
8e18257d PZ |
1938 | { |
1939 | struct task_struct *curr = current; | |
1940 | ||
c94aa5ca | 1941 | if (debug_locks_silent) |
f7c1c6b3 | 1942 | return; |
8e18257d | 1943 | |
681fbec8 | 1944 | pr_warn("\n"); |
a5dd63ef PM |
1945 | pr_warn("======================================================\n"); |
1946 | pr_warn("WARNING: possible circular locking dependency detected\n"); | |
fbdc4b9a | 1947 | print_kernel_ident(); |
a5dd63ef | 1948 | pr_warn("------------------------------------------------------\n"); |
681fbec8 | 1949 | pr_warn("%s/%d is trying to acquire lock:\n", |
ba25f9dc | 1950 | curr->comm, task_pid_nr(curr)); |
db0002a3 | 1951 | print_lock(check_src); |
383a4bc8 | 1952 | |
e966eaee | 1953 | pr_warn("\nbut task is already holding lock:\n"); |
383a4bc8 | 1954 | |
db0002a3 | 1955 | print_lock(check_tgt); |
681fbec8 PM |
1956 | pr_warn("\nwhich lock already depends on the new lock.\n\n"); |
1957 | pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); | |
8e18257d PZ |
1958 | |
1959 | print_circular_bug_entry(entry, depth); | |
8e18257d PZ |
1960 | } |
1961 | ||
68e30567 BF |
1962 | /* |
1963 | * We are about to add A -> B into the dependency graph, and in __bfs() a | |
1964 | * strong dependency path A -> .. -> B is found: hlock_class equals | |
1965 | * entry->class. | |
1966 | * | |
1967 | * If A -> .. -> B can replace A -> B in any __bfs() search (means the former | |
1968 | * is _stronger_ than or equal to the latter), we consider A -> B as redundant. | |
1969 | * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A | |
1970 | * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the | |
1971 | * dependency graph, as any strong path ..-> A -> B ->.. we can get with | |
1972 | * having dependency A -> B, we could already get a equivalent path ..-> A -> | |
e2db7592 | 1973 | * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. |
68e30567 BF |
1974 | * |
1975 | * We need to make sure both the start and the end of A -> .. -> B is not | |
1976 | * weaker than A -> B. For the start part, please see the comment in | |
1977 | * check_redundant(). For the end part, we need: | |
1978 | * | |
1979 | * Either | |
1980 | * | |
1981 | * a) A -> B is -(*R)-> (everything is not weaker than that) | |
1982 | * | |
1983 | * or | |
1984 | * | |
1985 | * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) | |
1986 | * | |
1987 | */ | |
1988 | static inline bool hlock_equal(struct lock_list *entry, void *data) | |
9e2d551e | 1989 | { |
68e30567 BF |
1990 | struct held_lock *hlock = (struct held_lock *)data; |
1991 | ||
1992 | return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ | |
1993 | (hlock->read == 2 || /* A -> B is -(*R)-> */ | |
1994 | !entry->only_xr); /* A -> .. -> B is -(*N)-> */ | |
9e2d551e ML |
1995 | } |
1996 | ||
9de0c9bb BF |
1997 | /* |
1998 | * We are about to add B -> A into the dependency graph, and in __bfs() a | |
1999 | * strong dependency path A -> .. -> B is found: hlock_class equals | |
2000 | * entry->class. | |
2001 | * | |
2002 | * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong | |
2003 | * dependency cycle, that means: | |
2004 | * | |
2005 | * Either | |
2006 | * | |
2007 | * a) B -> A is -(E*)-> | |
2008 | * | |
2009 | * or | |
2010 | * | |
2011 | * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B) | |
2012 | * | |
2013 | * as then we don't have -(*R)-> -(S*)-> in the cycle. | |
2014 | */ | |
2015 | static inline bool hlock_conflict(struct lock_list *entry, void *data) | |
2016 | { | |
2017 | struct held_lock *hlock = (struct held_lock *)data; | |
2018 | ||
2019 | return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ | |
2020 | (hlock->read == 0 || /* B -> A is -(E*)-> */ | |
2021 | !entry->only_xr); /* A -> .. -> B is -(*N)-> */ | |
2022 | } | |
2023 | ||
f7c1c6b3 | 2024 | static noinline void print_circular_bug(struct lock_list *this, |
9de0c9bb BF |
2025 | struct lock_list *target, |
2026 | struct held_lock *check_src, | |
2027 | struct held_lock *check_tgt) | |
8e18257d PZ |
2028 | { |
2029 | struct task_struct *curr = current; | |
c94aa5ca | 2030 | struct lock_list *parent; |
f4185812 | 2031 | struct lock_list *first_parent; |
24208ca7 | 2032 | int depth; |
8e18257d | 2033 | |
c94aa5ca | 2034 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
f7c1c6b3 | 2035 | return; |
8e18257d | 2036 | |
12593b74 BVA |
2037 | this->trace = save_trace(); |
2038 | if (!this->trace) | |
f7c1c6b3 | 2039 | return; |
8e18257d | 2040 | |
c94aa5ca ML |
2041 | depth = get_lock_depth(target); |
2042 | ||
db0002a3 | 2043 | print_circular_bug_header(target, depth, check_src, check_tgt); |
c94aa5ca ML |
2044 | |
2045 | parent = get_lock_parent(target); | |
f4185812 | 2046 | first_parent = parent; |
c94aa5ca ML |
2047 | |
2048 | while (parent) { | |
2049 | print_circular_bug_entry(parent, --depth); | |
2050 | parent = get_lock_parent(parent); | |
2051 | } | |
8e18257d PZ |
2052 | |
2053 | printk("\nother info that might help us debug this:\n\n"); | |
f4185812 SR |
2054 | print_circular_lock_scenario(check_src, check_tgt, |
2055 | first_parent); | |
2056 | ||
8e18257d PZ |
2057 | lockdep_print_held_locks(curr); |
2058 | ||
2059 | printk("\nstack backtrace:\n"); | |
2060 | dump_stack(); | |
8e18257d PZ |
2061 | } |
2062 | ||
f7c1c6b3 | 2063 | static noinline void print_bfs_bug(int ret) |
db0002a3 ML |
2064 | { |
2065 | if (!debug_locks_off_graph_unlock()) | |
f7c1c6b3 | 2066 | return; |
db0002a3 | 2067 | |
0119fee4 PZ |
2068 | /* |
2069 | * Breadth-first-search failed, graph got corrupted? | |
2070 | */ | |
db0002a3 | 2071 | WARN(1, "lockdep bfs error:%d\n", ret); |
db0002a3 ML |
2072 | } |
2073 | ||
61775ed2 | 2074 | static bool noop_count(struct lock_list *entry, void *data) |
419ca3f1 | 2075 | { |
ef681026 | 2076 | (*(unsigned long *)data)++; |
61775ed2 | 2077 | return false; |
ef681026 | 2078 | } |
419ca3f1 | 2079 | |
5216d530 | 2080 | static unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
ef681026 ML |
2081 | { |
2082 | unsigned long count = 0; | |
3f649ab7 | 2083 | struct lock_list *target_entry; |
419ca3f1 | 2084 | |
bc2dd71b | 2085 | __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry); |
419ca3f1 | 2086 | |
ef681026 | 2087 | return count; |
419ca3f1 | 2088 | } |
419ca3f1 DM |
2089 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
2090 | { | |
2091 | unsigned long ret, flags; | |
ef681026 ML |
2092 | struct lock_list this; |
2093 | ||
6971c0f3 | 2094 | __bfs_init_root(&this, class); |
419ca3f1 | 2095 | |
fcc784be | 2096 | raw_local_irq_save(flags); |
248efb21 | 2097 | lockdep_lock(); |
ef681026 | 2098 | ret = __lockdep_count_forward_deps(&this); |
248efb21 | 2099 | lockdep_unlock(); |
fcc784be | 2100 | raw_local_irq_restore(flags); |
419ca3f1 DM |
2101 | |
2102 | return ret; | |
2103 | } | |
2104 | ||
5216d530 | 2105 | static unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
419ca3f1 | 2106 | { |
ef681026 | 2107 | unsigned long count = 0; |
3f649ab7 | 2108 | struct lock_list *target_entry; |
419ca3f1 | 2109 | |
bc2dd71b | 2110 | __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry); |
419ca3f1 | 2111 | |
ef681026 | 2112 | return count; |
419ca3f1 DM |
2113 | } |
2114 | ||
2115 | unsigned long lockdep_count_backward_deps(struct lock_class *class) | |
2116 | { | |
2117 | unsigned long ret, flags; | |
ef681026 ML |
2118 | struct lock_list this; |
2119 | ||
6971c0f3 | 2120 | __bfs_init_root(&this, class); |
419ca3f1 | 2121 | |
fcc784be | 2122 | raw_local_irq_save(flags); |
248efb21 | 2123 | lockdep_lock(); |
ef681026 | 2124 | ret = __lockdep_count_backward_deps(&this); |
248efb21 | 2125 | lockdep_unlock(); |
fcc784be | 2126 | raw_local_irq_restore(flags); |
419ca3f1 DM |
2127 | |
2128 | return ret; | |
2129 | } | |
2130 | ||
8e18257d | 2131 | /* |
8c2c2b44 | 2132 | * Check that the dependency graph starting at <src> can lead to |
b11be024 | 2133 | * <target> or not. |
8e18257d | 2134 | */ |
b11be024 | 2135 | static noinline enum bfs_result |
9de0c9bb BF |
2136 | check_path(struct held_lock *target, struct lock_list *src_entry, |
2137 | bool (*match)(struct lock_list *entry, void *data), | |
bc2dd71b | 2138 | bool (*skip)(struct lock_list *entry, void *data), |
8c2c2b44 | 2139 | struct lock_list **target_entry) |
8e18257d | 2140 | { |
b11be024 | 2141 | enum bfs_result ret; |
8c2c2b44 | 2142 | |
bc2dd71b | 2143 | ret = __bfs_forwards(src_entry, target, match, skip, target_entry); |
8c2c2b44 | 2144 | |
b11be024 | 2145 | if (unlikely(bfs_error(ret))) |
8c2c2b44 YD |
2146 | print_bfs_bug(ret); |
2147 | ||
2148 | return ret; | |
2149 | } | |
2150 | ||
eb1cfd09 KO |
2151 | static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *); |
2152 | ||
8c2c2b44 YD |
2153 | /* |
2154 | * Prove that the dependency graph starting at <src> can not | |
2155 | * lead to <target>. If it can, there is a circle when adding | |
2156 | * <target> -> <src> dependency. | |
2157 | * | |
b11be024 | 2158 | * Print an error and return BFS_RMATCH if it does. |
8c2c2b44 | 2159 | */ |
b11be024 | 2160 | static noinline enum bfs_result |
8c2c2b44 | 2161 | check_noncircular(struct held_lock *src, struct held_lock *target, |
12593b74 | 2162 | struct lock_trace **const trace) |
8c2c2b44 | 2163 | { |
b11be024 | 2164 | enum bfs_result ret; |
3f649ab7 | 2165 | struct lock_list *target_entry; |
6971c0f3 BF |
2166 | struct lock_list src_entry; |
2167 | ||
2168 | bfs_init_root(&src_entry, src); | |
8e18257d | 2169 | |
bd6d29c2 | 2170 | debug_atomic_inc(nr_cyclic_checks); |
419ca3f1 | 2171 | |
bc2dd71b | 2172 | ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry); |
fbb9ce95 | 2173 | |
b11be024 | 2174 | if (unlikely(ret == BFS_RMATCH)) { |
12593b74 | 2175 | if (!*trace) { |
8c2c2b44 YD |
2176 | /* |
2177 | * If save_trace fails here, the printing might | |
2178 | * trigger a WARN but because of the !nr_entries it | |
2179 | * should not do bad things. | |
2180 | */ | |
12593b74 | 2181 | *trace = save_trace(); |
8c2c2b44 YD |
2182 | } |
2183 | ||
eb1cfd09 KO |
2184 | if (src->class_idx == target->class_idx) |
2185 | print_deadlock_bug(current, src, target); | |
2186 | else | |
2187 | print_circular_bug(&src_entry, target_entry, src, target); | |
8c2c2b44 YD |
2188 | } |
2189 | ||
2190 | return ret; | |
db0002a3 | 2191 | } |
c94aa5ca | 2192 | |
e7a38f63 | 2193 | #ifdef CONFIG_TRACE_IRQFLAGS |
948f8376 | 2194 | |
f08e3888 BF |
2195 | /* |
2196 | * Forwards and backwards subgraph searching, for the purposes of | |
2197 | * proving that two subgraphs can be connected by a new dependency | |
2198 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
2199 | * | |
2200 | * A irq safe->unsafe deadlock happens with the following conditions: | |
2201 | * | |
2202 | * 1) We have a strong dependency path A -> ... -> B | |
2203 | * | |
2204 | * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore | |
2205 | * irq can create a new dependency B -> A (consider the case that a holder | |
2206 | * of B gets interrupted by an irq whose handler will try to acquire A). | |
2207 | * | |
2208 | * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a | |
2209 | * strong circle: | |
2210 | * | |
2211 | * For the usage bits of B: | |
2212 | * a) if A -> B is -(*N)->, then B -> A could be any type, so any | |
2213 | * ENABLED_IRQ usage suffices. | |
2214 | * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only | |
2215 | * ENABLED_IRQ_*_READ usage suffices. | |
2216 | * | |
2217 | * For the usage bits of A: | |
2218 | * c) if A -> B is -(E*)->, then B -> A could be any type, so any | |
2219 | * USED_IN_IRQ usage suffices. | |
2220 | * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only | |
2221 | * USED_IN_IRQ_*_READ usage suffices. | |
2222 | */ | |
2223 | ||
2224 | /* | |
2225 | * There is a strong dependency path in the dependency graph: A -> B, and now | |
2226 | * we need to decide which usage bit of A should be accumulated to detect | |
2227 | * safe->unsafe bugs. | |
2228 | * | |
2229 | * Note that usage_accumulate() is used in backwards search, so ->only_xr | |
2230 | * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true). | |
2231 | * | |
2232 | * As above, if only_xr is false, which means A -> B has -(E*)-> dependency | |
2233 | * path, any usage of A should be considered. Otherwise, we should only | |
2234 | * consider _READ usage. | |
2235 | */ | |
61775ed2 | 2236 | static inline bool usage_accumulate(struct lock_list *entry, void *mask) |
948f8376 | 2237 | { |
f08e3888 BF |
2238 | if (!entry->only_xr) |
2239 | *(unsigned long *)mask |= entry->class->usage_mask; | |
2240 | else /* Mask out _READ usage bits */ | |
2241 | *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ); | |
948f8376 | 2242 | |
61775ed2 | 2243 | return false; |
948f8376 FW |
2244 | } |
2245 | ||
fbb9ce95 | 2246 | /* |
f08e3888 BF |
2247 | * There is a strong dependency path in the dependency graph: A -> B, and now |
2248 | * we need to decide which usage bit of B conflicts with the usage bits of A, | |
2249 | * i.e. which usage bit of B may introduce safe->unsafe deadlocks. | |
2250 | * | |
2251 | * As above, if only_xr is false, which means A -> B has -(*N)-> dependency | |
2252 | * path, any usage of B should be considered. Otherwise, we should only | |
2253 | * consider _READ usage. | |
fbb9ce95 | 2254 | */ |
61775ed2 | 2255 | static inline bool usage_match(struct lock_list *entry, void *mask) |
d7aaba14 | 2256 | { |
f08e3888 BF |
2257 | if (!entry->only_xr) |
2258 | return !!(entry->class->usage_mask & *(unsigned long *)mask); | |
2259 | else /* Mask out _READ usage bits */ | |
2260 | return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask); | |
d7aaba14 ML |
2261 | } |
2262 | ||
5f296240 BF |
2263 | static inline bool usage_skip(struct lock_list *entry, void *mask) |
2264 | { | |
0cce06ba PZ |
2265 | if (entry->class->lock_type == LD_LOCK_NORMAL) |
2266 | return false; | |
2267 | ||
5f296240 BF |
2268 | /* |
2269 | * Skip local_lock() for irq inversion detection. | |
2270 | * | |
2271 | * For !RT, local_lock() is not a real lock, so it won't carry any | |
2272 | * dependency. | |
2273 | * | |
2274 | * For RT, an irq inversion happens when we have lock A and B, and on | |
2275 | * some CPU we can have: | |
2276 | * | |
2277 | * lock(A); | |
2278 | * <interrupted> | |
2279 | * lock(B); | |
2280 | * | |
2281 | * where lock(B) cannot sleep, and we have a dependency B -> ... -> A. | |
2282 | * | |
2283 | * Now we prove local_lock() cannot exist in that dependency. First we | |
2284 | * have the observation for any lock chain L1 -> ... -> Ln, for any | |
2285 | * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise | |
2286 | * wait context check will complain. And since B is not a sleep lock, | |
2287 | * therefore B.inner_wait_type >= 2, and since the inner_wait_type of | |
2288 | * local_lock() is 3, which is greater than 2, therefore there is no | |
2289 | * way the local_lock() exists in the dependency B -> ... -> A. | |
2290 | * | |
2291 | * As a result, we will skip local_lock(), when we search for irq | |
2292 | * inversion bugs. | |
2293 | */ | |
0cce06ba PZ |
2294 | if (entry->class->lock_type == LD_LOCK_PERCPU && |
2295 | DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG)) | |
2296 | return false; | |
5f296240 | 2297 | |
0cce06ba PZ |
2298 | /* |
2299 | * Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually | |
2300 | * a lock and only used to override the wait_type. | |
2301 | */ | |
5f296240 | 2302 | |
0cce06ba | 2303 | return true; |
5f296240 BF |
2304 | } |
2305 | ||
fbb9ce95 IM |
2306 | /* |
2307 | * Find a node in the forwards-direction dependency sub-graph starting | |
d7aaba14 | 2308 | * at @root->class that matches @bit. |
fbb9ce95 | 2309 | * |
b11be024 | 2310 | * Return BFS_MATCH if such a node exists in the subgraph, and put that node |
d7aaba14 | 2311 | * into *@target_entry. |
fbb9ce95 | 2312 | */ |
b11be024 | 2313 | static enum bfs_result |
627f364d | 2314 | find_usage_forwards(struct lock_list *root, unsigned long usage_mask, |
d7aaba14 | 2315 | struct lock_list **target_entry) |
fbb9ce95 | 2316 | { |
b11be024 | 2317 | enum bfs_result result; |
fbb9ce95 | 2318 | |
bd6d29c2 | 2319 | debug_atomic_inc(nr_find_usage_forwards_checks); |
fbb9ce95 | 2320 | |
5f296240 | 2321 | result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry); |
d7aaba14 ML |
2322 | |
2323 | return result; | |
fbb9ce95 IM |
2324 | } |
2325 | ||
2326 | /* | |
2327 | * Find a node in the backwards-direction dependency sub-graph starting | |
d7aaba14 | 2328 | * at @root->class that matches @bit. |
fbb9ce95 | 2329 | */ |
b11be024 | 2330 | static enum bfs_result |
627f364d | 2331 | find_usage_backwards(struct lock_list *root, unsigned long usage_mask, |
d7aaba14 | 2332 | struct lock_list **target_entry) |
fbb9ce95 | 2333 | { |
b11be024 | 2334 | enum bfs_result result; |
fbb9ce95 | 2335 | |
bd6d29c2 | 2336 | debug_atomic_inc(nr_find_usage_backwards_checks); |
fbb9ce95 | 2337 | |
5f296240 | 2338 | result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry); |
f82b217e | 2339 | |
d7aaba14 | 2340 | return result; |
fbb9ce95 IM |
2341 | } |
2342 | ||
af012961 PZ |
2343 | static void print_lock_class_header(struct lock_class *class, int depth) |
2344 | { | |
2345 | int bit; | |
2346 | ||
2347 | printk("%*s->", depth, ""); | |
eb1cfd09 | 2348 | print_lock_name(NULL, class); |
8ca2b56c WL |
2349 | #ifdef CONFIG_DEBUG_LOCKDEP |
2350 | printk(KERN_CONT " ops: %lu", debug_class_ops_read(class)); | |
2351 | #endif | |
f943fe0f | 2352 | printk(KERN_CONT " {\n"); |
af012961 | 2353 | |
2bb8945b | 2354 | for (bit = 0; bit < LOCK_TRACE_STATES; bit++) { |
af012961 PZ |
2355 | if (class->usage_mask & (1 << bit)) { |
2356 | int len = depth; | |
2357 | ||
2358 | len += printk("%*s %s", depth, "", usage_str[bit]); | |
f943fe0f | 2359 | len += printk(KERN_CONT " at:\n"); |
12593b74 | 2360 | print_lock_trace(class->usage_traces[bit], len); |
af012961 PZ |
2361 | } |
2362 | } | |
2363 | printk("%*s }\n", depth, ""); | |
2364 | ||
04860d48 | 2365 | printk("%*s ... key at: [<%px>] %pS\n", |
f943fe0f | 2366 | depth, "", class->key, class->key); |
af012961 PZ |
2367 | } |
2368 | ||
2369 | /* | |
69c7a5fb BF |
2370 | * Dependency path printing: |
2371 | * | |
2372 | * After BFS we get a lock dependency path (linked via ->parent of lock_list), | |
2373 | * printing out each lock in the dependency path will help on understanding how | |
2374 | * the deadlock could happen. Here are some details about dependency path | |
2375 | * printing: | |
2376 | * | |
2377 | * 1) A lock_list can be either forwards or backwards for a lock dependency, | |
2378 | * for a lock dependency A -> B, there are two lock_lists: | |
2379 | * | |
2380 | * a) lock_list in the ->locks_after list of A, whose ->class is B and | |
2381 | * ->links_to is A. In this case, we can say the lock_list is | |
2382 | * "A -> B" (forwards case). | |
2383 | * | |
2384 | * b) lock_list in the ->locks_before list of B, whose ->class is A | |
2385 | * and ->links_to is B. In this case, we can say the lock_list is | |
2386 | * "B <- A" (bacwards case). | |
2387 | * | |
2388 | * The ->trace of both a) and b) point to the call trace where B was | |
2389 | * acquired with A held. | |
2390 | * | |
2391 | * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't | |
2392 | * represent a certain lock dependency, it only provides an initial entry | |
2393 | * for BFS. For example, BFS may introduce a "helper" lock_list whose | |
2394 | * ->class is A, as a result BFS will search all dependencies starting with | |
2395 | * A, e.g. A -> B or A -> C. | |
2396 | * | |
2397 | * The notation of a forwards helper lock_list is like "-> A", which means | |
2398 | * we should search the forwards dependencies starting with "A", e.g A -> B | |
2399 | * or A -> C. | |
2400 | * | |
2401 | * The notation of a bacwards helper lock_list is like "<- B", which means | |
2402 | * we should search the backwards dependencies ending with "B", e.g. | |
2403 | * B <- A or B <- C. | |
2404 | */ | |
2405 | ||
2406 | /* | |
2407 | * printk the shortest lock dependencies from @root to @leaf in reverse order. | |
2408 | * | |
2409 | * We have a lock dependency path as follow: | |
2410 | * | |
2411 | * @root @leaf | |
2412 | * | | | |
2413 | * V V | |
2414 | * ->parent ->parent | |
2415 | * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list | | |
2416 | * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln| | |
2417 | * | |
2418 | * , so it's natural that we start from @leaf and print every ->class and | |
2419 | * ->trace until we reach the @root. | |
af012961 PZ |
2420 | */ |
2421 | static void __used | |
2422 | print_shortest_lock_dependencies(struct lock_list *leaf, | |
f7c1c6b3 | 2423 | struct lock_list *root) |
af012961 PZ |
2424 | { |
2425 | struct lock_list *entry = leaf; | |
2426 | int depth; | |
2427 | ||
2428 | /*compute depth from generated tree by BFS*/ | |
2429 | depth = get_lock_depth(leaf); | |
2430 | ||
2431 | do { | |
2432 | print_lock_class_header(entry->class, depth); | |
2433 | printk("%*s ... acquired at:\n", depth, ""); | |
12593b74 | 2434 | print_lock_trace(entry->trace, 2); |
af012961 PZ |
2435 | printk("\n"); |
2436 | ||
2437 | if (depth == 0 && (entry != root)) { | |
6be8c393 | 2438 | printk("lockdep:%s bad path found in chain graph\n", __func__); |
af012961 PZ |
2439 | break; |
2440 | } | |
2441 | ||
2442 | entry = get_lock_parent(entry); | |
2443 | depth--; | |
2444 | } while (entry && (depth >= 0)); | |
af012961 | 2445 | } |
d7aaba14 | 2446 | |
69c7a5fb BF |
2447 | /* |
2448 | * printk the shortest lock dependencies from @leaf to @root. | |
2449 | * | |
2450 | * We have a lock dependency path (from a backwards search) as follow: | |
2451 | * | |
2452 | * @leaf @root | |
2453 | * | | | |
2454 | * V V | |
2455 | * ->parent ->parent | |
2456 | * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list | | |
2457 | * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln | | |
2458 | * | |
2459 | * , so when we iterate from @leaf to @root, we actually print the lock | |
2460 | * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order. | |
2461 | * | |
2462 | * Another thing to notice here is that ->class of L2 <- L1 is L1, while the | |
2463 | * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call | |
2464 | * trace of L1 in the dependency path, which is alright, because most of the | |
2465 | * time we can figure out where L1 is held from the call trace of L2. | |
2466 | */ | |
2467 | static void __used | |
2468 | print_shortest_lock_dependencies_backwards(struct lock_list *leaf, | |
2469 | struct lock_list *root) | |
2470 | { | |
2471 | struct lock_list *entry = leaf; | |
2472 | const struct lock_trace *trace = NULL; | |
2473 | int depth; | |
2474 | ||
2475 | /*compute depth from generated tree by BFS*/ | |
2476 | depth = get_lock_depth(leaf); | |
2477 | ||
2478 | do { | |
2479 | print_lock_class_header(entry->class, depth); | |
2480 | if (trace) { | |
2481 | printk("%*s ... acquired at:\n", depth, ""); | |
2482 | print_lock_trace(trace, 2); | |
2483 | printk("\n"); | |
2484 | } | |
2485 | ||
2486 | /* | |
2487 | * Record the pointer to the trace for the next lock_list | |
2488 | * entry, see the comments for the function. | |
2489 | */ | |
2490 | trace = entry->trace; | |
2491 | ||
2492 | if (depth == 0 && (entry != root)) { | |
2493 | printk("lockdep:%s bad path found in chain graph\n", __func__); | |
2494 | break; | |
2495 | } | |
2496 | ||
2497 | entry = get_lock_parent(entry); | |
2498 | depth--; | |
2499 | } while (entry && (depth >= 0)); | |
2500 | } | |
2501 | ||
3003eba3 SR |
2502 | static void |
2503 | print_irq_lock_scenario(struct lock_list *safe_entry, | |
2504 | struct lock_list *unsafe_entry, | |
dad3d743 SR |
2505 | struct lock_class *prev_class, |
2506 | struct lock_class *next_class) | |
3003eba3 SR |
2507 | { |
2508 | struct lock_class *safe_class = safe_entry->class; | |
2509 | struct lock_class *unsafe_class = unsafe_entry->class; | |
dad3d743 | 2510 | struct lock_class *middle_class = prev_class; |
3003eba3 SR |
2511 | |
2512 | if (middle_class == safe_class) | |
dad3d743 | 2513 | middle_class = next_class; |
3003eba3 SR |
2514 | |
2515 | /* | |
2516 | * A direct locking problem where unsafe_class lock is taken | |
2517 | * directly by safe_class lock, then all we need to show | |
2518 | * is the deadlock scenario, as it is obvious that the | |
2519 | * unsafe lock is taken under the safe lock. | |
2520 | * | |
2521 | * But if there is a chain instead, where the safe lock takes | |
2522 | * an intermediate lock (middle_class) where this lock is | |
2523 | * not the same as the safe lock, then the lock chain is | |
2524 | * used to describe the problem. Otherwise we would need | |
2525 | * to show a different CPU case for each link in the chain | |
2526 | * from the safe_class lock to the unsafe_class lock. | |
2527 | */ | |
2528 | if (middle_class != unsafe_class) { | |
2529 | printk("Chain exists of:\n "); | |
eb1cfd09 | 2530 | __print_lock_name(NULL, safe_class); |
f943fe0f | 2531 | printk(KERN_CONT " --> "); |
eb1cfd09 | 2532 | __print_lock_name(NULL, middle_class); |
f943fe0f | 2533 | printk(KERN_CONT " --> "); |
eb1cfd09 | 2534 | __print_lock_name(NULL, unsafe_class); |
f943fe0f | 2535 | printk(KERN_CONT "\n\n"); |
3003eba3 SR |
2536 | } |
2537 | ||
2538 | printk(" Possible interrupt unsafe locking scenario:\n\n"); | |
2539 | printk(" CPU0 CPU1\n"); | |
2540 | printk(" ---- ----\n"); | |
2541 | printk(" lock("); | |
eb1cfd09 | 2542 | __print_lock_name(NULL, unsafe_class); |
f943fe0f | 2543 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
2544 | printk(" local_irq_disable();\n"); |
2545 | printk(" lock("); | |
eb1cfd09 | 2546 | __print_lock_name(NULL, safe_class); |
f943fe0f | 2547 | printk(KERN_CONT ");\n"); |
3003eba3 | 2548 | printk(" lock("); |
eb1cfd09 | 2549 | __print_lock_name(NULL, middle_class); |
f943fe0f | 2550 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
2551 | printk(" <Interrupt>\n"); |
2552 | printk(" lock("); | |
eb1cfd09 | 2553 | __print_lock_name(NULL, safe_class); |
f943fe0f | 2554 | printk(KERN_CONT ");\n"); |
3003eba3 SR |
2555 | printk("\n *** DEADLOCK ***\n\n"); |
2556 | } | |
2557 | ||
f7c1c6b3 | 2558 | static void |
fbb9ce95 | 2559 | print_bad_irq_dependency(struct task_struct *curr, |
24208ca7 ML |
2560 | struct lock_list *prev_root, |
2561 | struct lock_list *next_root, | |
2562 | struct lock_list *backwards_entry, | |
2563 | struct lock_list *forwards_entry, | |
fbb9ce95 IM |
2564 | struct held_lock *prev, |
2565 | struct held_lock *next, | |
2566 | enum lock_usage_bit bit1, | |
2567 | enum lock_usage_bit bit2, | |
2568 | const char *irqclass) | |
2569 | { | |
74c383f1 | 2570 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
f7c1c6b3 | 2571 | return; |
fbb9ce95 | 2572 | |
681fbec8 | 2573 | pr_warn("\n"); |
a5dd63ef PM |
2574 | pr_warn("=====================================================\n"); |
2575 | pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", | |
fbb9ce95 | 2576 | irqclass, irqclass); |
fbdc4b9a | 2577 | print_kernel_ident(); |
a5dd63ef | 2578 | pr_warn("-----------------------------------------------------\n"); |
681fbec8 | 2579 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", |
ba25f9dc | 2580 | curr->comm, task_pid_nr(curr), |
f9ad4a5f | 2581 | lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, |
fbb9ce95 | 2582 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
f9ad4a5f | 2583 | lockdep_hardirqs_enabled(), |
fbb9ce95 IM |
2584 | curr->softirqs_enabled); |
2585 | print_lock(next); | |
2586 | ||
681fbec8 | 2587 | pr_warn("\nand this task is already holding:\n"); |
fbb9ce95 | 2588 | print_lock(prev); |
681fbec8 | 2589 | pr_warn("which would create a new lock dependency:\n"); |
eb1cfd09 | 2590 | print_lock_name(prev, hlock_class(prev)); |
681fbec8 | 2591 | pr_cont(" ->"); |
eb1cfd09 | 2592 | print_lock_name(next, hlock_class(next)); |
681fbec8 | 2593 | pr_cont("\n"); |
fbb9ce95 | 2594 | |
681fbec8 | 2595 | pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", |
fbb9ce95 | 2596 | irqclass); |
eb1cfd09 | 2597 | print_lock_name(NULL, backwards_entry->class); |
681fbec8 | 2598 | pr_warn("\n... which became %s-irq-safe at:\n", irqclass); |
fbb9ce95 | 2599 | |
12593b74 | 2600 | print_lock_trace(backwards_entry->class->usage_traces[bit1], 1); |
fbb9ce95 | 2601 | |
681fbec8 | 2602 | pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); |
eb1cfd09 | 2603 | print_lock_name(NULL, forwards_entry->class); |
681fbec8 PM |
2604 | pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); |
2605 | pr_warn("..."); | |
fbb9ce95 | 2606 | |
12593b74 | 2607 | print_lock_trace(forwards_entry->class->usage_traces[bit2], 1); |
fbb9ce95 | 2608 | |
681fbec8 | 2609 | pr_warn("\nother info that might help us debug this:\n\n"); |
dad3d743 SR |
2610 | print_irq_lock_scenario(backwards_entry, forwards_entry, |
2611 | hlock_class(prev), hlock_class(next)); | |
3003eba3 | 2612 | |
fbb9ce95 IM |
2613 | lockdep_print_held_locks(curr); |
2614 | ||
681fbec8 | 2615 | pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); |
69c7a5fb | 2616 | print_shortest_lock_dependencies_backwards(backwards_entry, prev_root); |
fbb9ce95 | 2617 | |
681fbec8 PM |
2618 | pr_warn("\nthe dependencies between the lock to be acquired"); |
2619 | pr_warn(" and %s-irq-unsafe lock:\n", irqclass); | |
12593b74 BVA |
2620 | next_root->trace = save_trace(); |
2621 | if (!next_root->trace) | |
f7c1c6b3 | 2622 | return; |
24208ca7 | 2623 | print_shortest_lock_dependencies(forwards_entry, next_root); |
fbb9ce95 | 2624 | |
681fbec8 | 2625 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 | 2626 | dump_stack(); |
fbb9ce95 IM |
2627 | } |
2628 | ||
4f367d8a PZ |
2629 | static const char *state_names[] = { |
2630 | #define LOCKDEP_STATE(__STATE) \ | |
b4b136f4 | 2631 | __stringify(__STATE), |
4f367d8a PZ |
2632 | #include "lockdep_states.h" |
2633 | #undef LOCKDEP_STATE | |
2634 | }; | |
2635 | ||
2636 | static const char *state_rnames[] = { | |
2637 | #define LOCKDEP_STATE(__STATE) \ | |
b4b136f4 | 2638 | __stringify(__STATE)"-READ", |
4f367d8a PZ |
2639 | #include "lockdep_states.h" |
2640 | #undef LOCKDEP_STATE | |
2641 | }; | |
2642 | ||
2643 | static inline const char *state_name(enum lock_usage_bit bit) | |
8e18257d | 2644 | { |
c902a1e8 FW |
2645 | if (bit & LOCK_USAGE_READ_MASK) |
2646 | return state_rnames[bit >> LOCK_USAGE_DIR_MASK]; | |
2647 | else | |
2648 | return state_names[bit >> LOCK_USAGE_DIR_MASK]; | |
4f367d8a | 2649 | } |
8e18257d | 2650 | |
948f8376 FW |
2651 | /* |
2652 | * The bit number is encoded like: | |
2653 | * | |
2654 | * bit0: 0 exclusive, 1 read lock | |
2655 | * bit1: 0 used in irq, 1 irq enabled | |
2656 | * bit2-n: state | |
2657 | */ | |
4f367d8a PZ |
2658 | static int exclusive_bit(int new_bit) |
2659 | { | |
bba2a8f1 FW |
2660 | int state = new_bit & LOCK_USAGE_STATE_MASK; |
2661 | int dir = new_bit & LOCK_USAGE_DIR_MASK; | |
8e18257d PZ |
2662 | |
2663 | /* | |
4f367d8a | 2664 | * keep state, bit flip the direction and strip read. |
8e18257d | 2665 | */ |
bba2a8f1 | 2666 | return state | (dir ^ LOCK_USAGE_DIR_MASK); |
4f367d8a PZ |
2667 | } |
2668 | ||
948f8376 FW |
2669 | /* |
2670 | * Observe that when given a bitmask where each bitnr is encoded as above, a | |
2671 | * right shift of the mask transforms the individual bitnrs as -1 and | |
2672 | * conversely, a left shift transforms into +1 for the individual bitnrs. | |
2673 | * | |
2674 | * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can | |
2675 | * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0) | |
2676 | * instead by subtracting the bit number by 2, or shifting the mask right by 2. | |
2677 | * | |
2678 | * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2. | |
2679 | * | |
2680 | * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is | |
2681 | * all bits set) and recompose with bitnr1 flipped. | |
2682 | */ | |
2683 | static unsigned long invert_dir_mask(unsigned long mask) | |
2684 | { | |
2685 | unsigned long excl = 0; | |
2686 | ||
2687 | /* Invert dir */ | |
2688 | excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK; | |
2689 | excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK; | |
2690 | ||
2691 | return excl; | |
2692 | } | |
2693 | ||
2694 | /* | |
f08e3888 BF |
2695 | * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ |
2696 | * usage may cause deadlock too, for example: | |
2697 | * | |
2698 | * P1 P2 | |
2699 | * <irq disabled> | |
2700 | * write_lock(l1); <irq enabled> | |
2701 | * read_lock(l2); | |
2702 | * write_lock(l2); | |
2703 | * <in irq> | |
2704 | * read_lock(l1); | |
2705 | * | |
2706 | * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2 | |
2707 | * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible | |
2708 | * deadlock. | |
2709 | * | |
2710 | * In fact, all of the following cases may cause deadlocks: | |
2711 | * | |
2712 | * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_* | |
2713 | * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_* | |
2714 | * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ | |
2715 | * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ | |
2716 | * | |
2717 | * As a result, to calculate the "exclusive mask", first we invert the | |
2718 | * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with | |
2719 | * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all | |
2720 | * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*). | |
948f8376 FW |
2721 | */ |
2722 | static unsigned long exclusive_mask(unsigned long mask) | |
2723 | { | |
2724 | unsigned long excl = invert_dir_mask(mask); | |
2725 | ||
948f8376 | 2726 | excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; |
f08e3888 | 2727 | excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; |
948f8376 FW |
2728 | |
2729 | return excl; | |
2730 | } | |
2731 | ||
2732 | /* | |
2733 | * Retrieve the _possible_ original mask to which @mask is | |
2734 | * exclusive. Ie: this is the opposite of exclusive_mask(). | |
2735 | * Note that 2 possible original bits can match an exclusive | |
2736 | * bit: one has LOCK_USAGE_READ_MASK set, the other has it | |
2737 | * cleared. So both are returned for each exclusive bit. | |
2738 | */ | |
2739 | static unsigned long original_mask(unsigned long mask) | |
2740 | { | |
2741 | unsigned long excl = invert_dir_mask(mask); | |
2742 | ||
2743 | /* Include read in existing usages */ | |
f08e3888 | 2744 | excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; |
948f8376 FW |
2745 | excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; |
2746 | ||
2747 | return excl; | |
2748 | } | |
2749 | ||
2750 | /* | |
2751 | * Find the first pair of bit match between an original | |
2752 | * usage mask and an exclusive usage mask. | |
2753 | */ | |
2754 | static int find_exclusive_match(unsigned long mask, | |
2755 | unsigned long excl_mask, | |
2756 | enum lock_usage_bit *bitp, | |
2757 | enum lock_usage_bit *excl_bitp) | |
2758 | { | |
f08e3888 | 2759 | int bit, excl, excl_read; |
948f8376 FW |
2760 | |
2761 | for_each_set_bit(bit, &mask, LOCK_USED) { | |
f08e3888 BF |
2762 | /* |
2763 | * exclusive_bit() strips the read bit, however, | |
2764 | * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need | |
2765 | * to search excl | LOCK_USAGE_READ_MASK as well. | |
2766 | */ | |
948f8376 | 2767 | excl = exclusive_bit(bit); |
f08e3888 | 2768 | excl_read = excl | LOCK_USAGE_READ_MASK; |
948f8376 FW |
2769 | if (excl_mask & lock_flag(excl)) { |
2770 | *bitp = bit; | |
2771 | *excl_bitp = excl; | |
2772 | return 0; | |
f08e3888 BF |
2773 | } else if (excl_mask & lock_flag(excl_read)) { |
2774 | *bitp = bit; | |
2775 | *excl_bitp = excl_read; | |
2776 | return 0; | |
948f8376 FW |
2777 | } |
2778 | } | |
2779 | return -1; | |
2780 | } | |
2781 | ||
2782 | /* | |
2783 | * Prove that the new dependency does not connect a hardirq-safe(-read) | |
2784 | * lock with a hardirq-unsafe lock - to achieve this we search | |
2785 | * the backwards-subgraph starting at <prev>, and the | |
2786 | * forwards-subgraph starting at <next>: | |
2787 | */ | |
4f367d8a | 2788 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
948f8376 | 2789 | struct held_lock *next) |
4f367d8a | 2790 | { |
948f8376 FW |
2791 | unsigned long usage_mask = 0, forward_mask, backward_mask; |
2792 | enum lock_usage_bit forward_bit = 0, backward_bit = 0; | |
3f649ab7 KC |
2793 | struct lock_list *target_entry1; |
2794 | struct lock_list *target_entry; | |
948f8376 | 2795 | struct lock_list this, that; |
b11be024 | 2796 | enum bfs_result ret; |
948f8376 | 2797 | |
8e18257d | 2798 | /* |
948f8376 FW |
2799 | * Step 1: gather all hard/soft IRQs usages backward in an |
2800 | * accumulated usage mask. | |
8e18257d | 2801 | */ |
f08e3888 | 2802 | bfs_init_rootb(&this, prev); |
8e18257d | 2803 | |
5f296240 | 2804 | ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL); |
b11be024 | 2805 | if (bfs_error(ret)) { |
f7c1c6b3 YD |
2806 | print_bfs_bug(ret); |
2807 | return 0; | |
2808 | } | |
8e18257d | 2809 | |
948f8376 FW |
2810 | usage_mask &= LOCKF_USED_IN_IRQ_ALL; |
2811 | if (!usage_mask) | |
2812 | return 1; | |
4f367d8a | 2813 | |
cf40bd16 | 2814 | /* |
948f8376 FW |
2815 | * Step 2: find exclusive uses forward that match the previous |
2816 | * backward accumulated mask. | |
cf40bd16 | 2817 | */ |
948f8376 | 2818 | forward_mask = exclusive_mask(usage_mask); |
cf40bd16 | 2819 | |
f08e3888 | 2820 | bfs_init_root(&that, next); |
4f367d8a | 2821 | |
948f8376 | 2822 | ret = find_usage_forwards(&that, forward_mask, &target_entry1); |
b11be024 | 2823 | if (bfs_error(ret)) { |
f7c1c6b3 YD |
2824 | print_bfs_bug(ret); |
2825 | return 0; | |
2826 | } | |
b11be024 BF |
2827 | if (ret == BFS_RNOMATCH) |
2828 | return 1; | |
cf40bd16 | 2829 | |
948f8376 FW |
2830 | /* |
2831 | * Step 3: we found a bad match! Now retrieve a lock from the backward | |
2832 | * list whose usage mask matches the exclusive usage mask from the | |
2833 | * lock found on the forward list. | |
7b1f8c61 BF |
2834 | * |
2835 | * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering | |
2836 | * the follow case: | |
2837 | * | |
2838 | * When trying to add A -> B to the graph, we find that there is a | |
2839 | * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M, | |
2840 | * that B -> ... -> M. However M is **softirq-safe**, if we use exact | |
2841 | * invert bits of M's usage_mask, we will find another lock N that is | |
2842 | * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not | |
2843 | * cause a inversion deadlock. | |
948f8376 | 2844 | */ |
7b1f8c61 | 2845 | backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL); |
948f8376 FW |
2846 | |
2847 | ret = find_usage_backwards(&this, backward_mask, &target_entry); | |
b11be024 | 2848 | if (bfs_error(ret)) { |
f7c1c6b3 YD |
2849 | print_bfs_bug(ret); |
2850 | return 0; | |
2851 | } | |
b11be024 | 2852 | if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH)) |
948f8376 FW |
2853 | return 1; |
2854 | ||
2855 | /* | |
2856 | * Step 4: narrow down to a pair of incompatible usage bits | |
2857 | * and report it. | |
2858 | */ | |
2859 | ret = find_exclusive_match(target_entry->class->usage_mask, | |
2860 | target_entry1->class->usage_mask, | |
2861 | &backward_bit, &forward_bit); | |
2862 | if (DEBUG_LOCKS_WARN_ON(ret == -1)) | |
2863 | return 1; | |
2864 | ||
f7c1c6b3 YD |
2865 | print_bad_irq_dependency(curr, &this, &that, |
2866 | target_entry, target_entry1, | |
2867 | prev, next, | |
2868 | backward_bit, forward_bit, | |
2869 | state_name(backward_bit)); | |
2870 | ||
2871 | return 0; | |
8e18257d PZ |
2872 | } |
2873 | ||
8e18257d PZ |
2874 | #else |
2875 | ||
948f8376 FW |
2876 | static inline int check_irq_usage(struct task_struct *curr, |
2877 | struct held_lock *prev, struct held_lock *next) | |
8e18257d PZ |
2878 | { |
2879 | return 1; | |
2880 | } | |
5f296240 BF |
2881 | |
2882 | static inline bool usage_skip(struct lock_list *entry, void *mask) | |
2883 | { | |
2884 | return false; | |
2885 | } | |
2886 | ||
b3b9c187 | 2887 | #endif /* CONFIG_TRACE_IRQFLAGS */ |
8e18257d | 2888 | |
175b1a60 PZ |
2889 | #ifdef CONFIG_LOCKDEP_SMALL |
2890 | /* | |
2891 | * Check that the dependency graph starting at <src> can lead to | |
2892 | * <target> or not. If it can, <src> -> <target> dependency is already | |
2893 | * in the graph. | |
2894 | * | |
0e8a89d4 | 2895 | * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if |
175b1a60 PZ |
2896 | * any error appears in the bfs search. |
2897 | */ | |
2898 | static noinline enum bfs_result | |
2899 | check_redundant(struct held_lock *src, struct held_lock *target) | |
2900 | { | |
2901 | enum bfs_result ret; | |
2902 | struct lock_list *target_entry; | |
2903 | struct lock_list src_entry; | |
2904 | ||
2905 | bfs_init_root(&src_entry, src); | |
2906 | /* | |
2907 | * Special setup for check_redundant(). | |
2908 | * | |
2909 | * To report redundant, we need to find a strong dependency path that | |
2910 | * is equal to or stronger than <src> -> <target>. So if <src> is E, | |
2911 | * we need to let __bfs() only search for a path starting at a -(E*)->, | |
2912 | * we achieve this by setting the initial node's ->only_xr to true in | |
2913 | * that case. And if <prev> is S, we set initial ->only_xr to false | |
2914 | * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant. | |
2915 | */ | |
2916 | src_entry.only_xr = src->read == 0; | |
2917 | ||
2918 | debug_atomic_inc(nr_redundant_checks); | |
2919 | ||
5f296240 BF |
2920 | /* |
2921 | * Note: we skip local_lock() for redundant check, because as the | |
2922 | * comment in usage_skip(), A -> local_lock() -> B and A -> B are not | |
2923 | * the same. | |
2924 | */ | |
2925 | ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry); | |
175b1a60 PZ |
2926 | |
2927 | if (ret == BFS_RMATCH) | |
2928 | debug_atomic_inc(nr_redundant); | |
2929 | ||
2930 | return ret; | |
2931 | } | |
2932 | ||
2933 | #else | |
2934 | ||
2935 | static inline enum bfs_result | |
2936 | check_redundant(struct held_lock *src, struct held_lock *target) | |
2937 | { | |
2938 | return BFS_RNOMATCH; | |
2939 | } | |
2940 | ||
2941 | #endif | |
2942 | ||
b3b9c187 | 2943 | static void inc_chains(int irq_context) |
8e18257d | 2944 | { |
b3b9c187 WL |
2945 | if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) |
2946 | nr_hardirq_chains++; | |
2947 | else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) | |
2948 | nr_softirq_chains++; | |
2949 | else | |
2950 | nr_process_chains++; | |
8e18257d PZ |
2951 | } |
2952 | ||
b3b9c187 WL |
2953 | static void dec_chains(int irq_context) |
2954 | { | |
2955 | if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) | |
2956 | nr_hardirq_chains--; | |
2957 | else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) | |
2958 | nr_softirq_chains--; | |
2959 | else | |
2960 | nr_process_chains--; | |
2961 | } | |
fbb9ce95 | 2962 | |
48702ecf | 2963 | static void |
f7c1c6b3 | 2964 | print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) |
48702ecf SR |
2965 | { |
2966 | struct lock_class *next = hlock_class(nxt); | |
2967 | struct lock_class *prev = hlock_class(prv); | |
2968 | ||
2969 | printk(" Possible unsafe locking scenario:\n\n"); | |
2970 | printk(" CPU0\n"); | |
2971 | printk(" ----\n"); | |
2972 | printk(" lock("); | |
eb1cfd09 | 2973 | __print_lock_name(prv, prev); |
f943fe0f | 2974 | printk(KERN_CONT ");\n"); |
48702ecf | 2975 | printk(" lock("); |
eb1cfd09 | 2976 | __print_lock_name(nxt, next); |
f943fe0f | 2977 | printk(KERN_CONT ");\n"); |
48702ecf SR |
2978 | printk("\n *** DEADLOCK ***\n\n"); |
2979 | printk(" May be due to missing lock nesting notation\n\n"); | |
2980 | } | |
2981 | ||
f7c1c6b3 | 2982 | static void |
fbb9ce95 IM |
2983 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
2984 | struct held_lock *next) | |
2985 | { | |
eb1cfd09 KO |
2986 | struct lock_class *class = hlock_class(prev); |
2987 | ||
74c383f1 | 2988 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
f7c1c6b3 | 2989 | return; |
fbb9ce95 | 2990 | |
681fbec8 | 2991 | pr_warn("\n"); |
a5dd63ef PM |
2992 | pr_warn("============================================\n"); |
2993 | pr_warn("WARNING: possible recursive locking detected\n"); | |
fbdc4b9a | 2994 | print_kernel_ident(); |
a5dd63ef | 2995 | pr_warn("--------------------------------------------\n"); |
681fbec8 | 2996 | pr_warn("%s/%d is trying to acquire lock:\n", |
ba25f9dc | 2997 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 | 2998 | print_lock(next); |
681fbec8 | 2999 | pr_warn("\nbut task is already holding lock:\n"); |
fbb9ce95 IM |
3000 | print_lock(prev); |
3001 | ||
eb1cfd09 KO |
3002 | if (class->cmp_fn) { |
3003 | pr_warn("and the lock comparison function returns %i:\n", | |
3004 | class->cmp_fn(prev->instance, next->instance)); | |
3005 | } | |
3006 | ||
681fbec8 | 3007 | pr_warn("\nother info that might help us debug this:\n"); |
48702ecf | 3008 | print_deadlock_scenario(next, prev); |
fbb9ce95 IM |
3009 | lockdep_print_held_locks(curr); |
3010 | ||
681fbec8 | 3011 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 | 3012 | dump_stack(); |
fbb9ce95 IM |
3013 | } |
3014 | ||
3015 | /* | |
3016 | * Check whether we are holding such a class already. | |
3017 | * | |
3018 | * (Note that this has to be done separately, because the graph cannot | |
3019 | * detect such classes of deadlocks.) | |
3020 | * | |
d61fc96a BF |
3021 | * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same |
3022 | * lock class is held but nest_lock is also held, i.e. we rely on the | |
3023 | * nest_lock to avoid the deadlock. | |
fbb9ce95 IM |
3024 | */ |
3025 | static int | |
4609c4f9 | 3026 | check_deadlock(struct task_struct *curr, struct held_lock *next) |
fbb9ce95 | 3027 | { |
eb1cfd09 | 3028 | struct lock_class *class; |
fbb9ce95 | 3029 | struct held_lock *prev; |
7531e2f3 | 3030 | struct held_lock *nest = NULL; |
fbb9ce95 IM |
3031 | int i; |
3032 | ||
3033 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3034 | prev = curr->held_locks + i; | |
7531e2f3 PZ |
3035 | |
3036 | if (prev->instance == next->nest_lock) | |
3037 | nest = prev; | |
3038 | ||
f82b217e | 3039 | if (hlock_class(prev) != hlock_class(next)) |
fbb9ce95 | 3040 | continue; |
7531e2f3 | 3041 | |
fbb9ce95 IM |
3042 | /* |
3043 | * Allow read-after-read recursion of the same | |
6c9076ec | 3044 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
fbb9ce95 | 3045 | */ |
4609c4f9 | 3046 | if ((next->read == 2) && prev->read) |
d61fc96a | 3047 | continue; |
7531e2f3 | 3048 | |
eb1cfd09 KO |
3049 | class = hlock_class(prev); |
3050 | ||
3051 | if (class->cmp_fn && | |
3052 | class->cmp_fn(prev->instance, next->instance) < 0) | |
3053 | continue; | |
3054 | ||
7531e2f3 PZ |
3055 | /* |
3056 | * We're holding the nest_lock, which serializes this lock's | |
3057 | * nesting behaviour. | |
3058 | */ | |
3059 | if (nest) | |
3060 | return 2; | |
3061 | ||
f7c1c6b3 YD |
3062 | print_deadlock_bug(curr, prev, next); |
3063 | return 0; | |
fbb9ce95 IM |
3064 | } |
3065 | return 1; | |
3066 | } | |
3067 | ||
3068 | /* | |
3069 | * There was a chain-cache miss, and we are about to add a new dependency | |
154f185e | 3070 | * to a previous lock. We validate the following rules: |
fbb9ce95 IM |
3071 | * |
3072 | * - would the adding of the <prev> -> <next> dependency create a | |
3073 | * circular dependency in the graph? [== circular deadlock] | |
3074 | * | |
3075 | * - does the new prev->next dependency connect any hardirq-safe lock | |
3076 | * (in the full backwards-subgraph starting at <prev>) with any | |
3077 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
3078 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
3079 | * | |
3080 | * - does the new prev->next dependency connect any softirq-safe lock | |
3081 | * (in the full backwards-subgraph starting at <prev>) with any | |
3082 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
3083 | * <next>)? [== illegal lock inversion with softirq contexts] | |
3084 | * | |
3085 | * any of these scenarios could lead to a deadlock. | |
3086 | * | |
3087 | * Then if all the validations pass, we add the forwards and backwards | |
3088 | * dependency. | |
3089 | */ | |
3090 | static int | |
3091 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
bd76eca1 | 3092 | struct held_lock *next, u16 distance, |
12593b74 | 3093 | struct lock_trace **const trace) |
fbb9ce95 IM |
3094 | { |
3095 | struct lock_list *entry; | |
b11be024 | 3096 | enum bfs_result ret; |
fbb9ce95 | 3097 | |
a0b0fd53 BVA |
3098 | if (!hlock_class(prev)->key || !hlock_class(next)->key) { |
3099 | /* | |
3100 | * The warning statements below may trigger a use-after-free | |
3101 | * of the class name. It is better to trigger a use-after free | |
3102 | * and to have the class name most of the time instead of not | |
3103 | * having the class name available. | |
3104 | */ | |
3105 | WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key, | |
3106 | "Detected use-after-free of lock class %px/%s\n", | |
3107 | hlock_class(prev), | |
3108 | hlock_class(prev)->name); | |
3109 | WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key, | |
3110 | "Detected use-after-free of lock class %px/%s\n", | |
3111 | hlock_class(next), | |
3112 | hlock_class(next)->name); | |
3113 | return 2; | |
3114 | } | |
3115 | ||
eb1cfd09 KO |
3116 | if (prev->class_idx == next->class_idx) { |
3117 | struct lock_class *class = hlock_class(prev); | |
3118 | ||
3119 | if (class->cmp_fn && | |
3120 | class->cmp_fn(prev->instance, next->instance) < 0) | |
3121 | return 2; | |
3122 | } | |
3123 | ||
fbb9ce95 IM |
3124 | /* |
3125 | * Prove that the new <prev> -> <next> dependency would not | |
3126 | * create a circular dependency in the graph. (We do this by | |
154f185e YD |
3127 | * a breadth-first search into the graph starting at <next>, |
3128 | * and check whether we can reach <prev>.) | |
fbb9ce95 | 3129 | * |
154f185e YD |
3130 | * The search is limited by the size of the circular queue (i.e., |
3131 | * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes | |
3132 | * in the graph whose neighbours are to be checked. | |
fbb9ce95 | 3133 | */ |
8c2c2b44 | 3134 | ret = check_noncircular(next, prev, trace); |
b11be024 | 3135 | if (unlikely(bfs_error(ret) || ret == BFS_RMATCH)) |
f7c1c6b3 | 3136 | return 0; |
c94aa5ca | 3137 | |
948f8376 | 3138 | if (!check_irq_usage(curr, prev, next)) |
fbb9ce95 IM |
3139 | return 0; |
3140 | ||
fbb9ce95 IM |
3141 | /* |
3142 | * Is the <prev> -> <next> dependency already present? | |
3143 | * | |
3144 | * (this may occur even though this is a new chain: consider | |
3145 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
3146 | * chains - the second one will be new, but L1 already has | |
3147 | * L2 added to its dependency list, due to the first chain.) | |
3148 | */ | |
f82b217e DJ |
3149 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
3150 | if (entry->class == hlock_class(next)) { | |
068135e6 JB |
3151 | if (distance == 1) |
3152 | entry->distance = 1; | |
3454a36d BF |
3153 | entry->dep |= calc_dep(prev, next); |
3154 | ||
3155 | /* | |
3156 | * Also, update the reverse dependency in @next's | |
3157 | * ->locks_before list. | |
3158 | * | |
3159 | * Here we reuse @entry as the cursor, which is fine | |
3160 | * because we won't go to the next iteration of the | |
3161 | * outer loop: | |
3162 | * | |
3163 | * For normal cases, we return in the inner loop. | |
3164 | * | |
3165 | * If we fail to return, we have inconsistency, i.e. | |
3166 | * <prev>::locks_after contains <next> while | |
3167 | * <next>::locks_before doesn't contain <prev>. In | |
3168 | * that case, we return after the inner and indicate | |
3169 | * something is wrong. | |
3170 | */ | |
3171 | list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) { | |
3172 | if (entry->class == hlock_class(prev)) { | |
3173 | if (distance == 1) | |
3174 | entry->distance = 1; | |
3175 | entry->dep |= calc_depb(prev, next); | |
3176 | return 1; | |
3177 | } | |
3178 | } | |
3179 | ||
3180 | /* <prev> is not found in <next>::locks_before */ | |
3181 | return 0; | |
068135e6 | 3182 | } |
fbb9ce95 IM |
3183 | } |
3184 | ||
ae813308 PZ |
3185 | /* |
3186 | * Is the <prev> -> <next> link redundant? | |
3187 | */ | |
8c2c2b44 | 3188 | ret = check_redundant(prev, next); |
b11be024 BF |
3189 | if (bfs_error(ret)) |
3190 | return 0; | |
3191 | else if (ret == BFS_RMATCH) | |
3192 | return 2; | |
ae813308 | 3193 | |
12593b74 BVA |
3194 | if (!*trace) { |
3195 | *trace = save_trace(); | |
3196 | if (!*trace) | |
3197 | return 0; | |
3198 | } | |
4726f2a6 | 3199 | |
fbb9ce95 IM |
3200 | /* |
3201 | * Ok, all validations passed, add the new lock | |
3202 | * to the previous lock's dependency list: | |
3203 | */ | |
86cffb80 | 3204 | ret = add_lock_to_list(hlock_class(next), hlock_class(prev), |
8b023acc ND |
3205 | &hlock_class(prev)->locks_after, distance, |
3206 | calc_dep(prev, next), *trace); | |
068135e6 | 3207 | |
fbb9ce95 IM |
3208 | if (!ret) |
3209 | return 0; | |
910b1b2e | 3210 | |
86cffb80 | 3211 | ret = add_lock_to_list(hlock_class(prev), hlock_class(next), |
8b023acc ND |
3212 | &hlock_class(next)->locks_before, distance, |
3213 | calc_depb(prev, next), *trace); | |
910b1b2e JP |
3214 | if (!ret) |
3215 | return 0; | |
fbb9ce95 | 3216 | |
70911fdc | 3217 | return 2; |
8e18257d | 3218 | } |
fbb9ce95 | 3219 | |
8e18257d PZ |
3220 | /* |
3221 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
3222 | * The ones that are relevant are (in increasing distance from curr): | |
3223 | * all consecutive trylock entries and the final non-trylock entry - or | |
3224 | * the end of this context's lock-chain - whichever comes first. | |
3225 | */ | |
3226 | static int | |
3227 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
3228 | { | |
12593b74 | 3229 | struct lock_trace *trace = NULL; |
8e18257d PZ |
3230 | int depth = curr->lockdep_depth; |
3231 | struct held_lock *hlock; | |
d6d897ce | 3232 | |
fbb9ce95 | 3233 | /* |
8e18257d PZ |
3234 | * Debugging checks. |
3235 | * | |
3236 | * Depth must not be zero for a non-head lock: | |
fbb9ce95 | 3237 | */ |
8e18257d PZ |
3238 | if (!depth) |
3239 | goto out_bug; | |
fbb9ce95 | 3240 | /* |
8e18257d PZ |
3241 | * At least two relevant locks must exist for this |
3242 | * to be a head: | |
fbb9ce95 | 3243 | */ |
8e18257d PZ |
3244 | if (curr->held_locks[depth].irq_context != |
3245 | curr->held_locks[depth-1].irq_context) | |
3246 | goto out_bug; | |
74c383f1 | 3247 | |
8e18257d | 3248 | for (;;) { |
bd76eca1 | 3249 | u16 distance = curr->lockdep_depth - depth + 1; |
1b5ff816 | 3250 | hlock = curr->held_locks + depth - 1; |
e966eaee | 3251 | |
621c9dac BF |
3252 | if (hlock->check) { |
3253 | int ret = check_prev_add(curr, hlock, next, distance, &trace); | |
e966eaee IM |
3254 | if (!ret) |
3255 | return 0; | |
3256 | ||
ce07a941 | 3257 | /* |
e966eaee IM |
3258 | * Stop after the first non-trylock entry, |
3259 | * as non-trylock entries have added their | |
3260 | * own direct dependencies already, so this | |
3261 | * lock is connected to them indirectly: | |
ce07a941 | 3262 | */ |
e966eaee IM |
3263 | if (!hlock->trylock) |
3264 | break; | |
74c383f1 | 3265 | } |
e966eaee | 3266 | |
8e18257d PZ |
3267 | depth--; |
3268 | /* | |
3269 | * End of lock-stack? | |
3270 | */ | |
3271 | if (!depth) | |
3272 | break; | |
3273 | /* | |
3274 | * Stop the search if we cross into another context: | |
3275 | */ | |
3276 | if (curr->held_locks[depth].irq_context != | |
3277 | curr->held_locks[depth-1].irq_context) | |
3278 | break; | |
fbb9ce95 | 3279 | } |
8e18257d PZ |
3280 | return 1; |
3281 | out_bug: | |
3282 | if (!debug_locks_off_graph_unlock()) | |
3283 | return 0; | |
fbb9ce95 | 3284 | |
0119fee4 PZ |
3285 | /* |
3286 | * Clearly we all shouldn't be here, but since we made it we | |
3287 | * can reliable say we messed up our state. See the above two | |
3288 | * gotos for reasons why we could possibly end up here. | |
3289 | */ | |
8e18257d | 3290 | WARN_ON(1); |
fbb9ce95 | 3291 | |
8e18257d | 3292 | return 0; |
fbb9ce95 IM |
3293 | } |
3294 | ||
443cd507 | 3295 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
de4643a7 | 3296 | static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS); |
443cd507 | 3297 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
797b82eb | 3298 | unsigned long nr_zapped_lock_chains; |
810507fe WL |
3299 | unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */ |
3300 | unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */ | |
3301 | unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */ | |
3302 | ||
3303 | /* | |
3304 | * The first 2 chain_hlocks entries in the chain block in the bucket | |
3305 | * list contains the following meta data: | |
3306 | * | |
3307 | * entry[0]: | |
3308 | * Bit 15 - always set to 1 (it is not a class index) | |
3309 | * Bits 0-14 - upper 15 bits of the next block index | |
3310 | * entry[1] - lower 16 bits of next block index | |
3311 | * | |
3312 | * A next block index of all 1 bits means it is the end of the list. | |
3313 | * | |
3314 | * On the unsized bucket (bucket-0), the 3rd and 4th entries contain | |
3315 | * the chain block size: | |
3316 | * | |
3317 | * entry[2] - upper 16 bits of the chain block size | |
3318 | * entry[3] - lower 16 bits of the chain block size | |
3319 | */ | |
3320 | #define MAX_CHAIN_BUCKETS 16 | |
3321 | #define CHAIN_BLK_FLAG (1U << 15) | |
3322 | #define CHAIN_BLK_LIST_END 0xFFFFU | |
3323 | ||
3324 | static int chain_block_buckets[MAX_CHAIN_BUCKETS]; | |
3325 | ||
3326 | static inline int size_to_bucket(int size) | |
3327 | { | |
3328 | if (size > MAX_CHAIN_BUCKETS) | |
3329 | return 0; | |
3330 | ||
3331 | return size - 1; | |
3332 | } | |
3333 | ||
3334 | /* | |
3335 | * Iterate all the chain blocks in a bucket. | |
3336 | */ | |
3337 | #define for_each_chain_block(bucket, prev, curr) \ | |
3338 | for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \ | |
3339 | (curr) >= 0; \ | |
3340 | (prev) = (curr), (curr) = chain_block_next(curr)) | |
3341 | ||
3342 | /* | |
3343 | * next block or -1 | |
3344 | */ | |
3345 | static inline int chain_block_next(int offset) | |
3346 | { | |
3347 | int next = chain_hlocks[offset]; | |
3348 | ||
3349 | WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG)); | |
3350 | ||
3351 | if (next == CHAIN_BLK_LIST_END) | |
3352 | return -1; | |
3353 | ||
3354 | next &= ~CHAIN_BLK_FLAG; | |
3355 | next <<= 16; | |
3356 | next |= chain_hlocks[offset + 1]; | |
3357 | ||
3358 | return next; | |
3359 | } | |
3360 | ||
3361 | /* | |
3362 | * bucket-0 only | |
3363 | */ | |
3364 | static inline int chain_block_size(int offset) | |
3365 | { | |
3366 | return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3]; | |
3367 | } | |
3368 | ||
3369 | static inline void init_chain_block(int offset, int next, int bucket, int size) | |
3370 | { | |
3371 | chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG; | |
3372 | chain_hlocks[offset + 1] = (u16)next; | |
3373 | ||
3374 | if (size && !bucket) { | |
3375 | chain_hlocks[offset + 2] = size >> 16; | |
3376 | chain_hlocks[offset + 3] = (u16)size; | |
3377 | } | |
3378 | } | |
3379 | ||
3380 | static inline void add_chain_block(int offset, int size) | |
3381 | { | |
3382 | int bucket = size_to_bucket(size); | |
3383 | int next = chain_block_buckets[bucket]; | |
3384 | int prev, curr; | |
3385 | ||
3386 | if (unlikely(size < 2)) { | |
3387 | /* | |
3388 | * We can't store single entries on the freelist. Leak them. | |
3389 | * | |
3390 | * One possible way out would be to uniquely mark them, other | |
3391 | * than with CHAIN_BLK_FLAG, such that we can recover them when | |
3392 | * the block before it is re-added. | |
3393 | */ | |
3394 | if (size) | |
3395 | nr_lost_chain_hlocks++; | |
3396 | return; | |
3397 | } | |
3398 | ||
3399 | nr_free_chain_hlocks += size; | |
3400 | if (!bucket) { | |
3401 | nr_large_chain_blocks++; | |
3402 | ||
3403 | /* | |
3404 | * Variable sized, sort large to small. | |
3405 | */ | |
3406 | for_each_chain_block(0, prev, curr) { | |
3407 | if (size >= chain_block_size(curr)) | |
3408 | break; | |
3409 | } | |
3410 | init_chain_block(offset, curr, 0, size); | |
3411 | if (prev < 0) | |
3412 | chain_block_buckets[0] = offset; | |
3413 | else | |
3414 | init_chain_block(prev, offset, 0, 0); | |
3415 | return; | |
3416 | } | |
3417 | /* | |
3418 | * Fixed size, add to head. | |
3419 | */ | |
3420 | init_chain_block(offset, next, bucket, size); | |
3421 | chain_block_buckets[bucket] = offset; | |
3422 | } | |
3423 | ||
3424 | /* | |
3425 | * Only the first block in the list can be deleted. | |
3426 | * | |
3427 | * For the variable size bucket[0], the first block (the largest one) is | |
3428 | * returned, broken up and put back into the pool. So if a chain block of | |
3429 | * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be | |
3430 | * queued up after the primordial chain block and never be used until the | |
3431 | * hlock entries in the primordial chain block is almost used up. That | |
3432 | * causes fragmentation and reduce allocation efficiency. That can be | |
3433 | * monitored by looking at the "large chain blocks" number in lockdep_stats. | |
3434 | */ | |
3435 | static inline void del_chain_block(int bucket, int size, int next) | |
3436 | { | |
3437 | nr_free_chain_hlocks -= size; | |
3438 | chain_block_buckets[bucket] = next; | |
3439 | ||
3440 | if (!bucket) | |
3441 | nr_large_chain_blocks--; | |
3442 | } | |
3443 | ||
3444 | static void init_chain_block_buckets(void) | |
3445 | { | |
3446 | int i; | |
3447 | ||
3448 | for (i = 0; i < MAX_CHAIN_BUCKETS; i++) | |
3449 | chain_block_buckets[i] = -1; | |
3450 | ||
3451 | add_chain_block(0, ARRAY_SIZE(chain_hlocks)); | |
3452 | } | |
3453 | ||
3454 | /* | |
3455 | * Return offset of a chain block of the right size or -1 if not found. | |
3456 | * | |
3457 | * Fairly simple worst-fit allocator with the addition of a number of size | |
3458 | * specific free lists. | |
3459 | */ | |
3460 | static int alloc_chain_hlocks(int req) | |
3461 | { | |
3462 | int bucket, curr, size; | |
3463 | ||
3464 | /* | |
3465 | * We rely on the MSB to act as an escape bit to denote freelist | |
3466 | * pointers. Make sure this bit isn't set in 'normal' class_idx usage. | |
3467 | */ | |
3468 | BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG); | |
3469 | ||
3470 | init_data_structures_once(); | |
3471 | ||
3472 | if (nr_free_chain_hlocks < req) | |
3473 | return -1; | |
3474 | ||
3475 | /* | |
3476 | * We require a minimum of 2 (u16) entries to encode a freelist | |
3477 | * 'pointer'. | |
3478 | */ | |
3479 | req = max(req, 2); | |
3480 | bucket = size_to_bucket(req); | |
3481 | curr = chain_block_buckets[bucket]; | |
3482 | ||
3483 | if (bucket) { | |
3484 | if (curr >= 0) { | |
3485 | del_chain_block(bucket, req, chain_block_next(curr)); | |
3486 | return curr; | |
3487 | } | |
3488 | /* Try bucket 0 */ | |
3489 | curr = chain_block_buckets[0]; | |
3490 | } | |
3491 | ||
3492 | /* | |
3493 | * The variable sized freelist is sorted by size; the first entry is | |
3494 | * the largest. Use it if it fits. | |
3495 | */ | |
3496 | if (curr >= 0) { | |
3497 | size = chain_block_size(curr); | |
3498 | if (likely(size >= req)) { | |
3499 | del_chain_block(0, size, chain_block_next(curr)); | |
bca4104b PZ |
3500 | if (size > req) |
3501 | add_chain_block(curr + req, size - req); | |
810507fe WL |
3502 | return curr; |
3503 | } | |
3504 | } | |
3505 | ||
3506 | /* | |
3507 | * Last resort, split a block in a larger sized bucket. | |
3508 | */ | |
3509 | for (size = MAX_CHAIN_BUCKETS; size > req; size--) { | |
3510 | bucket = size_to_bucket(size); | |
3511 | curr = chain_block_buckets[bucket]; | |
3512 | if (curr < 0) | |
3513 | continue; | |
3514 | ||
3515 | del_chain_block(bucket, size, chain_block_next(curr)); | |
3516 | add_chain_block(curr + req, size - req); | |
3517 | return curr; | |
3518 | } | |
3519 | ||
3520 | return -1; | |
3521 | } | |
3522 | ||
3523 | static inline void free_chain_hlocks(int base, int size) | |
3524 | { | |
3525 | add_chain_block(base, max(size, 2)); | |
3526 | } | |
443cd507 HY |
3527 | |
3528 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) | |
3529 | { | |
f611e8cf BF |
3530 | u16 chain_hlock = chain_hlocks[chain->base + i]; |
3531 | unsigned int class_idx = chain_hlock_class_idx(chain_hlock); | |
3532 | ||
28df029d | 3533 | return lock_classes + class_idx; |
443cd507 | 3534 | } |
8e18257d | 3535 | |
9e4e7554 IM |
3536 | /* |
3537 | * Returns the index of the first held_lock of the current chain | |
3538 | */ | |
3539 | static inline int get_first_held_lock(struct task_struct *curr, | |
3540 | struct held_lock *hlock) | |
3541 | { | |
3542 | int i; | |
3543 | struct held_lock *hlock_curr; | |
3544 | ||
3545 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { | |
3546 | hlock_curr = curr->held_locks + i; | |
3547 | if (hlock_curr->irq_context != hlock->irq_context) | |
3548 | break; | |
3549 | ||
3550 | } | |
3551 | ||
3552 | return ++i; | |
3553 | } | |
3554 | ||
5c8a010c | 3555 | #ifdef CONFIG_DEBUG_LOCKDEP |
39e2e173 AAF |
3556 | /* |
3557 | * Returns the next chain_key iteration | |
3558 | */ | |
f611e8cf | 3559 | static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key) |
39e2e173 | 3560 | { |
f611e8cf | 3561 | u64 new_chain_key = iterate_chain_key(chain_key, hlock_id); |
39e2e173 | 3562 | |
f611e8cf BF |
3563 | printk(" hlock_id:%d -> chain_key:%016Lx", |
3564 | (unsigned int)hlock_id, | |
39e2e173 AAF |
3565 | (unsigned long long)new_chain_key); |
3566 | return new_chain_key; | |
3567 | } | |
3568 | ||
3569 | static void | |
3570 | print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) | |
3571 | { | |
3572 | struct held_lock *hlock; | |
f6ec8829 | 3573 | u64 chain_key = INITIAL_CHAIN_KEY; |
39e2e173 | 3574 | int depth = curr->lockdep_depth; |
834494b2 | 3575 | int i = get_first_held_lock(curr, hlock_next); |
39e2e173 | 3576 | |
834494b2 YD |
3577 | printk("depth: %u (irq_context %u)\n", depth - i + 1, |
3578 | hlock_next->irq_context); | |
3579 | for (; i < depth; i++) { | |
39e2e173 | 3580 | hlock = curr->held_locks + i; |
f611e8cf | 3581 | chain_key = print_chain_key_iteration(hlock_id(hlock), chain_key); |
39e2e173 AAF |
3582 | |
3583 | print_lock(hlock); | |
3584 | } | |
3585 | ||
f611e8cf | 3586 | print_chain_key_iteration(hlock_id(hlock_next), chain_key); |
39e2e173 AAF |
3587 | print_lock(hlock_next); |
3588 | } | |
3589 | ||
3590 | static void print_chain_keys_chain(struct lock_chain *chain) | |
3591 | { | |
3592 | int i; | |
f6ec8829 | 3593 | u64 chain_key = INITIAL_CHAIN_KEY; |
f611e8cf | 3594 | u16 hlock_id; |
39e2e173 AAF |
3595 | |
3596 | printk("depth: %u\n", chain->depth); | |
3597 | for (i = 0; i < chain->depth; i++) { | |
f611e8cf BF |
3598 | hlock_id = chain_hlocks[chain->base + i]; |
3599 | chain_key = print_chain_key_iteration(hlock_id, chain_key); | |
39e2e173 | 3600 | |
eb1cfd09 | 3601 | print_lock_name(NULL, lock_classes + chain_hlock_class_idx(hlock_id)); |
39e2e173 AAF |
3602 | printk("\n"); |
3603 | } | |
3604 | } | |
3605 | ||
3606 | static void print_collision(struct task_struct *curr, | |
3607 | struct held_lock *hlock_next, | |
3608 | struct lock_chain *chain) | |
3609 | { | |
681fbec8 | 3610 | pr_warn("\n"); |
a5dd63ef PM |
3611 | pr_warn("============================\n"); |
3612 | pr_warn("WARNING: chain_key collision\n"); | |
39e2e173 | 3613 | print_kernel_ident(); |
a5dd63ef | 3614 | pr_warn("----------------------------\n"); |
681fbec8 PM |
3615 | pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); |
3616 | pr_warn("Hash chain already cached but the contents don't match!\n"); | |
39e2e173 | 3617 | |
681fbec8 | 3618 | pr_warn("Held locks:"); |
39e2e173 AAF |
3619 | print_chain_keys_held_locks(curr, hlock_next); |
3620 | ||
681fbec8 | 3621 | pr_warn("Locks in cached chain:"); |
39e2e173 AAF |
3622 | print_chain_keys_chain(chain); |
3623 | ||
681fbec8 | 3624 | pr_warn("\nstack backtrace:\n"); |
39e2e173 AAF |
3625 | dump_stack(); |
3626 | } | |
5c8a010c | 3627 | #endif |
39e2e173 | 3628 | |
9e4e7554 IM |
3629 | /* |
3630 | * Checks whether the chain and the current held locks are consistent | |
3631 | * in depth and also in content. If they are not it most likely means | |
3632 | * that there was a collision during the calculation of the chain_key. | |
3633 | * Returns: 0 not passed, 1 passed | |
3634 | */ | |
3635 | static int check_no_collision(struct task_struct *curr, | |
3636 | struct held_lock *hlock, | |
3637 | struct lock_chain *chain) | |
3638 | { | |
3639 | #ifdef CONFIG_DEBUG_LOCKDEP | |
3640 | int i, j, id; | |
3641 | ||
3642 | i = get_first_held_lock(curr, hlock); | |
3643 | ||
39e2e173 AAF |
3644 | if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { |
3645 | print_collision(curr, hlock, chain); | |
9e4e7554 | 3646 | return 0; |
39e2e173 | 3647 | } |
9e4e7554 IM |
3648 | |
3649 | for (j = 0; j < chain->depth - 1; j++, i++) { | |
f611e8cf | 3650 | id = hlock_id(&curr->held_locks[i]); |
9e4e7554 | 3651 | |
39e2e173 AAF |
3652 | if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { |
3653 | print_collision(curr, hlock, chain); | |
9e4e7554 | 3654 | return 0; |
39e2e173 | 3655 | } |
9e4e7554 IM |
3656 | } |
3657 | #endif | |
3658 | return 1; | |
3659 | } | |
3660 | ||
2212684a BVA |
3661 | /* |
3662 | * Given an index that is >= -1, return the index of the next lock chain. | |
3663 | * Return -2 if there is no next lock chain. | |
3664 | */ | |
3665 | long lockdep_next_lockchain(long i) | |
3666 | { | |
de4643a7 BVA |
3667 | i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1); |
3668 | return i < ARRAY_SIZE(lock_chains) ? i : -2; | |
2212684a BVA |
3669 | } |
3670 | ||
3671 | unsigned long lock_chain_count(void) | |
3672 | { | |
de4643a7 BVA |
3673 | return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains)); |
3674 | } | |
3675 | ||
3676 | /* Must be called with the graph lock held. */ | |
3677 | static struct lock_chain *alloc_lock_chain(void) | |
3678 | { | |
3679 | int idx = find_first_zero_bit(lock_chains_in_use, | |
3680 | ARRAY_SIZE(lock_chains)); | |
3681 | ||
3682 | if (unlikely(idx >= ARRAY_SIZE(lock_chains))) | |
3683 | return NULL; | |
3684 | __set_bit(idx, lock_chains_in_use); | |
3685 | return lock_chains + idx; | |
2212684a BVA |
3686 | } |
3687 | ||
fbb9ce95 | 3688 | /* |
545c23f2 BP |
3689 | * Adds a dependency chain into chain hashtable. And must be called with |
3690 | * graph_lock held. | |
3691 | * | |
3692 | * Return 0 if fail, and graph_lock is released. | |
3693 | * Return 1 if succeed, with graph_lock held. | |
fbb9ce95 | 3694 | */ |
545c23f2 BP |
3695 | static inline int add_chain_cache(struct task_struct *curr, |
3696 | struct held_lock *hlock, | |
3697 | u64 chain_key) | |
fbb9ce95 | 3698 | { |
a63f38cc | 3699 | struct hlist_head *hash_head = chainhashentry(chain_key); |
fbb9ce95 | 3700 | struct lock_chain *chain; |
e0944ee6 | 3701 | int i, j; |
fbb9ce95 | 3702 | |
0119fee4 | 3703 | /* |
527af3ea | 3704 | * The caller must hold the graph lock, ensure we've got IRQs |
0119fee4 PZ |
3705 | * disabled to make this an IRQ-safe lock.. for recursion reasons |
3706 | * lockdep won't complain about its own locking errors. | |
3707 | */ | |
248efb21 | 3708 | if (lockdep_assert_locked()) |
381a2292 | 3709 | return 0; |
9e4e7554 | 3710 | |
de4643a7 BVA |
3711 | chain = alloc_lock_chain(); |
3712 | if (!chain) { | |
74c383f1 IM |
3713 | if (!debug_locks_off_graph_unlock()) |
3714 | return 0; | |
3715 | ||
2c522836 | 3716 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); |
eedeeabd | 3717 | dump_stack(); |
fbb9ce95 IM |
3718 | return 0; |
3719 | } | |
fbb9ce95 | 3720 | chain->chain_key = chain_key; |
443cd507 | 3721 | chain->irq_context = hlock->irq_context; |
9e4e7554 | 3722 | i = get_first_held_lock(curr, hlock); |
443cd507 | 3723 | chain->depth = curr->lockdep_depth + 1 - i; |
75dd602a PZ |
3724 | |
3725 | BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); | |
3726 | BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); | |
3727 | BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); | |
3728 | ||
810507fe WL |
3729 | j = alloc_chain_hlocks(chain->depth); |
3730 | if (j < 0) { | |
f9af456a | 3731 | if (!debug_locks_off_graph_unlock()) |
75dd602a PZ |
3732 | return 0; |
3733 | ||
3734 | print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); | |
3735 | dump_stack(); | |
3736 | return 0; | |
3737 | } | |
75dd602a | 3738 | |
810507fe WL |
3739 | chain->base = j; |
3740 | for (j = 0; j < chain->depth - 1; j++, i++) { | |
f611e8cf | 3741 | int lock_id = hlock_id(curr->held_locks + i); |
810507fe WL |
3742 | |
3743 | chain_hlocks[chain->base + j] = lock_id; | |
3744 | } | |
f611e8cf | 3745 | chain_hlocks[chain->base + j] = hlock_id(hlock); |
a63f38cc | 3746 | hlist_add_head_rcu(&chain->entry, hash_head); |
bd6d29c2 | 3747 | debug_atomic_inc(chain_lookup_misses); |
b3b9c187 | 3748 | inc_chains(chain->irq_context); |
8e18257d PZ |
3749 | |
3750 | return 1; | |
3751 | } | |
3752 | ||
545c23f2 | 3753 | /* |
a0b0fd53 BVA |
3754 | * Look up a dependency chain. Must be called with either the graph lock or |
3755 | * the RCU read lock held. | |
545c23f2 BP |
3756 | */ |
3757 | static inline struct lock_chain *lookup_chain_cache(u64 chain_key) | |
3758 | { | |
3759 | struct hlist_head *hash_head = chainhashentry(chain_key); | |
3760 | struct lock_chain *chain; | |
3761 | ||
545c23f2 | 3762 | hlist_for_each_entry_rcu(chain, hash_head, entry) { |
a0b0fd53 | 3763 | if (READ_ONCE(chain->chain_key) == chain_key) { |
545c23f2 BP |
3764 | debug_atomic_inc(chain_lookup_hits); |
3765 | return chain; | |
3766 | } | |
3767 | } | |
3768 | return NULL; | |
3769 | } | |
3770 | ||
3771 | /* | |
3772 | * If the key is not present yet in dependency chain cache then | |
3773 | * add it and return 1 - in this case the new dependency chain is | |
3774 | * validated. If the key is already hashed, return 0. | |
3775 | * (On return with 1 graph_lock is held.) | |
3776 | */ | |
3777 | static inline int lookup_chain_cache_add(struct task_struct *curr, | |
3778 | struct held_lock *hlock, | |
3779 | u64 chain_key) | |
3780 | { | |
3781 | struct lock_class *class = hlock_class(hlock); | |
3782 | struct lock_chain *chain = lookup_chain_cache(chain_key); | |
3783 | ||
3784 | if (chain) { | |
3785 | cache_hit: | |
3786 | if (!check_no_collision(curr, hlock, chain)) | |
3787 | return 0; | |
3788 | ||
3789 | if (very_verbose(class)) { | |
3790 | printk("\nhash chain already cached, key: " | |
04860d48 | 3791 | "%016Lx tail class: [%px] %s\n", |
545c23f2 BP |
3792 | (unsigned long long)chain_key, |
3793 | class->key, class->name); | |
3794 | } | |
3795 | ||
3796 | return 0; | |
3797 | } | |
3798 | ||
3799 | if (very_verbose(class)) { | |
04860d48 | 3800 | printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n", |
545c23f2 BP |
3801 | (unsigned long long)chain_key, class->key, class->name); |
3802 | } | |
3803 | ||
3804 | if (!graph_lock()) | |
3805 | return 0; | |
3806 | ||
3807 | /* | |
3808 | * We have to walk the chain again locked - to avoid duplicates: | |
3809 | */ | |
3810 | chain = lookup_chain_cache(chain_key); | |
3811 | if (chain) { | |
3812 | graph_unlock(); | |
3813 | goto cache_hit; | |
3814 | } | |
3815 | ||
3816 | if (!add_chain_cache(curr, hlock, chain_key)) | |
3817 | return 0; | |
3818 | ||
3819 | return 1; | |
3820 | } | |
3821 | ||
0b9fc8ec YD |
3822 | static int validate_chain(struct task_struct *curr, |
3823 | struct held_lock *hlock, | |
3824 | int chain_head, u64 chain_key) | |
8e18257d PZ |
3825 | { |
3826 | /* | |
3827 | * Trylock needs to maintain the stack of held locks, but it | |
3828 | * does not add new dependencies, because trylock can be done | |
3829 | * in any order. | |
3830 | * | |
3831 | * We look up the chain_key and do the O(N^2) check and update of | |
3832 | * the dependencies only if this is a new dependency chain. | |
545c23f2 | 3833 | * (If lookup_chain_cache_add() return with 1 it acquires |
8e18257d PZ |
3834 | * graph_lock for us) |
3835 | */ | |
fb9edbe9 | 3836 | if (!hlock->trylock && hlock->check && |
545c23f2 | 3837 | lookup_chain_cache_add(curr, hlock, chain_key)) { |
8e18257d PZ |
3838 | /* |
3839 | * Check whether last held lock: | |
3840 | * | |
3841 | * - is irq-safe, if this lock is irq-unsafe | |
3842 | * - is softirq-safe, if this lock is hardirq-unsafe | |
3843 | * | |
3844 | * And check whether the new lock's dependency graph | |
31a490e5 | 3845 | * could lead back to the previous lock: |
8e18257d | 3846 | * |
31a490e5 YD |
3847 | * - within the current held-lock stack |
3848 | * - across our accumulated lock dependency records | |
3849 | * | |
3850 | * any of these scenarios could lead to a deadlock. | |
3851 | */ | |
3852 | /* | |
3853 | * The simple case: does the current hold the same lock | |
3854 | * already? | |
8e18257d | 3855 | */ |
4609c4f9 | 3856 | int ret = check_deadlock(curr, hlock); |
8e18257d PZ |
3857 | |
3858 | if (!ret) | |
3859 | return 0; | |
8e18257d PZ |
3860 | /* |
3861 | * Add dependency only if this lock is not the head | |
d61fc96a BF |
3862 | * of the chain, and if the new lock introduces no more |
3863 | * lock dependency (because we already hold a lock with the | |
3864 | * same lock class) nor deadlock (because the nest_lock | |
3865 | * serializes nesting locks), see the comments for | |
3866 | * check_deadlock(). | |
8e18257d | 3867 | */ |
545c23f2 | 3868 | if (!chain_head && ret != 2) { |
8e18257d PZ |
3869 | if (!check_prevs_add(curr, hlock)) |
3870 | return 0; | |
545c23f2 BP |
3871 | } |
3872 | ||
8e18257d | 3873 | graph_unlock(); |
545c23f2 BP |
3874 | } else { |
3875 | /* after lookup_chain_cache_add(): */ | |
8e18257d PZ |
3876 | if (unlikely(!debug_locks)) |
3877 | return 0; | |
545c23f2 | 3878 | } |
fbb9ce95 IM |
3879 | |
3880 | return 1; | |
3881 | } | |
8e18257d PZ |
3882 | #else |
3883 | static inline int validate_chain(struct task_struct *curr, | |
0b9fc8ec YD |
3884 | struct held_lock *hlock, |
3885 | int chain_head, u64 chain_key) | |
8e18257d PZ |
3886 | { |
3887 | return 1; | |
3888 | } | |
810507fe WL |
3889 | |
3890 | static void init_chain_block_buckets(void) { } | |
e7a38f63 | 3891 | #endif /* CONFIG_PROVE_LOCKING */ |
fbb9ce95 IM |
3892 | |
3893 | /* | |
3894 | * We are building curr_chain_key incrementally, so double-check | |
3895 | * it from scratch, to make sure that it's done correctly: | |
3896 | */ | |
1d09daa5 | 3897 | static void check_chain_key(struct task_struct *curr) |
fbb9ce95 IM |
3898 | { |
3899 | #ifdef CONFIG_DEBUG_LOCKDEP | |
3900 | struct held_lock *hlock, *prev_hlock = NULL; | |
5f18ab5c | 3901 | unsigned int i; |
f6ec8829 | 3902 | u64 chain_key = INITIAL_CHAIN_KEY; |
fbb9ce95 IM |
3903 | |
3904 | for (i = 0; i < curr->lockdep_depth; i++) { | |
3905 | hlock = curr->held_locks + i; | |
3906 | if (chain_key != hlock->prev_chain_key) { | |
3907 | debug_locks_off(); | |
0119fee4 PZ |
3908 | /* |
3909 | * We got mighty confused, our chain keys don't match | |
3910 | * with what we expect, someone trample on our task state? | |
3911 | */ | |
2df8b1d6 | 3912 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", |
fbb9ce95 IM |
3913 | curr->lockdep_depth, i, |
3914 | (unsigned long long)chain_key, | |
3915 | (unsigned long long)hlock->prev_chain_key); | |
fbb9ce95 IM |
3916 | return; |
3917 | } | |
01bb6f0a | 3918 | |
0119fee4 | 3919 | /* |
01bb6f0a YD |
3920 | * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is |
3921 | * it registered lock class index? | |
0119fee4 | 3922 | */ |
01bb6f0a | 3923 | if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use))) |
381a2292 JP |
3924 | return; |
3925 | ||
fbb9ce95 IM |
3926 | if (prev_hlock && (prev_hlock->irq_context != |
3927 | hlock->irq_context)) | |
f6ec8829 | 3928 | chain_key = INITIAL_CHAIN_KEY; |
f611e8cf | 3929 | chain_key = iterate_chain_key(chain_key, hlock_id(hlock)); |
fbb9ce95 IM |
3930 | prev_hlock = hlock; |
3931 | } | |
3932 | if (chain_key != curr->curr_chain_key) { | |
3933 | debug_locks_off(); | |
0119fee4 PZ |
3934 | /* |
3935 | * More smoking hash instead of calculating it, damn see these | |
3936 | * numbers float.. I bet that a pink elephant stepped on my memory. | |
3937 | */ | |
2df8b1d6 | 3938 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", |
fbb9ce95 IM |
3939 | curr->lockdep_depth, i, |
3940 | (unsigned long long)chain_key, | |
3941 | (unsigned long long)curr->curr_chain_key); | |
fbb9ce95 IM |
3942 | } |
3943 | #endif | |
3944 | } | |
3945 | ||
30a35f79 | 3946 | #ifdef CONFIG_PROVE_LOCKING |
0d2cc3b3 FW |
3947 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
3948 | enum lock_usage_bit new_bit); | |
3949 | ||
f7c1c6b3 | 3950 | static void print_usage_bug_scenario(struct held_lock *lock) |
282b5c2f SR |
3951 | { |
3952 | struct lock_class *class = hlock_class(lock); | |
3953 | ||
3954 | printk(" Possible unsafe locking scenario:\n\n"); | |
3955 | printk(" CPU0\n"); | |
3956 | printk(" ----\n"); | |
3957 | printk(" lock("); | |
eb1cfd09 | 3958 | __print_lock_name(lock, class); |
f943fe0f | 3959 | printk(KERN_CONT ");\n"); |
282b5c2f SR |
3960 | printk(" <Interrupt>\n"); |
3961 | printk(" lock("); | |
eb1cfd09 | 3962 | __print_lock_name(lock, class); |
f943fe0f | 3963 | printk(KERN_CONT ");\n"); |
282b5c2f SR |
3964 | printk("\n *** DEADLOCK ***\n\n"); |
3965 | } | |
3966 | ||
f7c1c6b3 | 3967 | static void |
8e18257d PZ |
3968 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
3969 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
3970 | { | |
7f82e631 | 3971 | if (!debug_locks_off() || debug_locks_silent) |
f7c1c6b3 | 3972 | return; |
8e18257d | 3973 | |
681fbec8 | 3974 | pr_warn("\n"); |
a5dd63ef PM |
3975 | pr_warn("================================\n"); |
3976 | pr_warn("WARNING: inconsistent lock state\n"); | |
fbdc4b9a | 3977 | print_kernel_ident(); |
a5dd63ef | 3978 | pr_warn("--------------------------------\n"); |
8e18257d | 3979 | |
681fbec8 | 3980 | pr_warn("inconsistent {%s} -> {%s} usage.\n", |
8e18257d PZ |
3981 | usage_str[prev_bit], usage_str[new_bit]); |
3982 | ||
681fbec8 | 3983 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", |
ba25f9dc | 3984 | curr->comm, task_pid_nr(curr), |
f9ad4a5f | 3985 | lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, |
ef996916 | 3986 | lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
f9ad4a5f | 3987 | lockdep_hardirqs_enabled(), |
ef996916 | 3988 | lockdep_softirqs_enabled(curr)); |
8e18257d PZ |
3989 | print_lock(this); |
3990 | ||
681fbec8 | 3991 | pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); |
12593b74 | 3992 | print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1); |
8e18257d PZ |
3993 | |
3994 | print_irqtrace_events(curr); | |
681fbec8 | 3995 | pr_warn("\nother info that might help us debug this:\n"); |
282b5c2f SR |
3996 | print_usage_bug_scenario(this); |
3997 | ||
8e18257d PZ |
3998 | lockdep_print_held_locks(curr); |
3999 | ||
681fbec8 | 4000 | pr_warn("\nstack backtrace:\n"); |
8e18257d | 4001 | dump_stack(); |
8e18257d PZ |
4002 | } |
4003 | ||
4004 | /* | |
4005 | * Print out an error if an invalid bit is set: | |
4006 | */ | |
4007 | static inline int | |
4008 | valid_state(struct task_struct *curr, struct held_lock *this, | |
4009 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
4010 | { | |
f7c1c6b3 | 4011 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { |
7f82e631 | 4012 | graph_unlock(); |
f7c1c6b3 YD |
4013 | print_usage_bug(curr, this, bad_bit, new_bit); |
4014 | return 0; | |
4015 | } | |
8e18257d PZ |
4016 | return 1; |
4017 | } | |
4018 | ||
fbb9ce95 IM |
4019 | |
4020 | /* | |
4021 | * print irq inversion bug: | |
4022 | */ | |
f7c1c6b3 | 4023 | static void |
24208ca7 ML |
4024 | print_irq_inversion_bug(struct task_struct *curr, |
4025 | struct lock_list *root, struct lock_list *other, | |
fbb9ce95 IM |
4026 | struct held_lock *this, int forwards, |
4027 | const char *irqclass) | |
4028 | { | |
dad3d743 SR |
4029 | struct lock_list *entry = other; |
4030 | struct lock_list *middle = NULL; | |
4031 | int depth; | |
4032 | ||
74c383f1 | 4033 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
f7c1c6b3 | 4034 | return; |
fbb9ce95 | 4035 | |
681fbec8 | 4036 | pr_warn("\n"); |
a5dd63ef PM |
4037 | pr_warn("========================================================\n"); |
4038 | pr_warn("WARNING: possible irq lock inversion dependency detected\n"); | |
fbdc4b9a | 4039 | print_kernel_ident(); |
a5dd63ef | 4040 | pr_warn("--------------------------------------------------------\n"); |
681fbec8 | 4041 | pr_warn("%s/%d just changed the state of lock:\n", |
ba25f9dc | 4042 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 IM |
4043 | print_lock(this); |
4044 | if (forwards) | |
681fbec8 | 4045 | pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); |
fbb9ce95 | 4046 | else |
681fbec8 | 4047 | pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); |
eb1cfd09 | 4048 | print_lock_name(NULL, other->class); |
681fbec8 | 4049 | pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); |
fbb9ce95 | 4050 | |
681fbec8 | 4051 | pr_warn("\nother info that might help us debug this:\n"); |
dad3d743 SR |
4052 | |
4053 | /* Find a middle lock (if one exists) */ | |
4054 | depth = get_lock_depth(other); | |
4055 | do { | |
4056 | if (depth == 0 && (entry != root)) { | |
681fbec8 | 4057 | pr_warn("lockdep:%s bad path found in chain graph\n", __func__); |
dad3d743 SR |
4058 | break; |
4059 | } | |
4060 | middle = entry; | |
4061 | entry = get_lock_parent(entry); | |
4062 | depth--; | |
4063 | } while (entry && entry != root && (depth >= 0)); | |
4064 | if (forwards) | |
4065 | print_irq_lock_scenario(root, other, | |
4066 | middle ? middle->class : root->class, other->class); | |
4067 | else | |
4068 | print_irq_lock_scenario(other, root, | |
4069 | middle ? middle->class : other->class, root->class); | |
4070 | ||
fbb9ce95 IM |
4071 | lockdep_print_held_locks(curr); |
4072 | ||
681fbec8 | 4073 | pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); |
12593b74 BVA |
4074 | root->trace = save_trace(); |
4075 | if (!root->trace) | |
f7c1c6b3 | 4076 | return; |
24208ca7 | 4077 | print_shortest_lock_dependencies(other, root); |
fbb9ce95 | 4078 | |
681fbec8 | 4079 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 | 4080 | dump_stack(); |
fbb9ce95 IM |
4081 | } |
4082 | ||
4083 | /* | |
4084 | * Prove that in the forwards-direction subgraph starting at <this> | |
4085 | * there is no lock matching <mask>: | |
4086 | */ | |
4087 | static int | |
4088 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
f08e3888 | 4089 | enum lock_usage_bit bit) |
fbb9ce95 | 4090 | { |
b11be024 | 4091 | enum bfs_result ret; |
d7aaba14 | 4092 | struct lock_list root; |
3f649ab7 | 4093 | struct lock_list *target_entry; |
f08e3888 BF |
4094 | enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK; |
4095 | unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit); | |
fbb9ce95 | 4096 | |
6971c0f3 | 4097 | bfs_init_root(&root, this); |
f08e3888 | 4098 | ret = find_usage_forwards(&root, usage_mask, &target_entry); |
b11be024 | 4099 | if (bfs_error(ret)) { |
f7c1c6b3 YD |
4100 | print_bfs_bug(ret); |
4101 | return 0; | |
4102 | } | |
b11be024 BF |
4103 | if (ret == BFS_RNOMATCH) |
4104 | return 1; | |
fbb9ce95 | 4105 | |
f08e3888 BF |
4106 | /* Check whether write or read usage is the match */ |
4107 | if (target_entry->class->usage_mask & lock_flag(bit)) { | |
4108 | print_irq_inversion_bug(curr, &root, target_entry, | |
4109 | this, 1, state_name(bit)); | |
4110 | } else { | |
4111 | print_irq_inversion_bug(curr, &root, target_entry, | |
4112 | this, 1, state_name(read_bit)); | |
4113 | } | |
4114 | ||
f7c1c6b3 | 4115 | return 0; |
fbb9ce95 IM |
4116 | } |
4117 | ||
4118 | /* | |
4119 | * Prove that in the backwards-direction subgraph starting at <this> | |
4120 | * there is no lock matching <mask>: | |
4121 | */ | |
4122 | static int | |
4123 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
f08e3888 | 4124 | enum lock_usage_bit bit) |
fbb9ce95 | 4125 | { |
b11be024 | 4126 | enum bfs_result ret; |
d7aaba14 | 4127 | struct lock_list root; |
3f649ab7 | 4128 | struct lock_list *target_entry; |
f08e3888 BF |
4129 | enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK; |
4130 | unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit); | |
fbb9ce95 | 4131 | |
6971c0f3 | 4132 | bfs_init_rootb(&root, this); |
f08e3888 | 4133 | ret = find_usage_backwards(&root, usage_mask, &target_entry); |
b11be024 | 4134 | if (bfs_error(ret)) { |
f7c1c6b3 YD |
4135 | print_bfs_bug(ret); |
4136 | return 0; | |
4137 | } | |
b11be024 BF |
4138 | if (ret == BFS_RNOMATCH) |
4139 | return 1; | |
fbb9ce95 | 4140 | |
f08e3888 BF |
4141 | /* Check whether write or read usage is the match */ |
4142 | if (target_entry->class->usage_mask & lock_flag(bit)) { | |
4143 | print_irq_inversion_bug(curr, &root, target_entry, | |
4144 | this, 0, state_name(bit)); | |
4145 | } else { | |
4146 | print_irq_inversion_bug(curr, &root, target_entry, | |
4147 | this, 0, state_name(read_bit)); | |
4148 | } | |
4149 | ||
f7c1c6b3 | 4150 | return 0; |
fbb9ce95 IM |
4151 | } |
4152 | ||
3117df04 | 4153 | void print_irqtrace_events(struct task_struct *curr) |
fbb9ce95 | 4154 | { |
0584df9c ME |
4155 | const struct irqtrace_events *trace = &curr->irqtrace; |
4156 | ||
4157 | printk("irq event stamp: %u\n", trace->irq_events); | |
04860d48 | 4158 | printk("hardirqs last enabled at (%u): [<%px>] %pS\n", |
0584df9c ME |
4159 | trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip, |
4160 | (void *)trace->hardirq_enable_ip); | |
04860d48 | 4161 | printk("hardirqs last disabled at (%u): [<%px>] %pS\n", |
0584df9c ME |
4162 | trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip, |
4163 | (void *)trace->hardirq_disable_ip); | |
04860d48 | 4164 | printk("softirqs last enabled at (%u): [<%px>] %pS\n", |
0584df9c ME |
4165 | trace->softirq_enable_event, (void *)trace->softirq_enable_ip, |
4166 | (void *)trace->softirq_enable_ip); | |
04860d48 | 4167 | printk("softirqs last disabled at (%u): [<%px>] %pS\n", |
0584df9c ME |
4168 | trace->softirq_disable_event, (void *)trace->softirq_disable_ip, |
4169 | (void *)trace->softirq_disable_ip); | |
fbb9ce95 IM |
4170 | } |
4171 | ||
cd95302d | 4172 | static int HARDIRQ_verbose(struct lock_class *class) |
fbb9ce95 | 4173 | { |
8e18257d PZ |
4174 | #if HARDIRQ_VERBOSE |
4175 | return class_filter(class); | |
4176 | #endif | |
fbb9ce95 IM |
4177 | return 0; |
4178 | } | |
4179 | ||
cd95302d | 4180 | static int SOFTIRQ_verbose(struct lock_class *class) |
fbb9ce95 | 4181 | { |
8e18257d PZ |
4182 | #if SOFTIRQ_VERBOSE |
4183 | return class_filter(class); | |
4184 | #endif | |
4185 | return 0; | |
fbb9ce95 IM |
4186 | } |
4187 | ||
cd95302d PZ |
4188 | static int (*state_verbose_f[])(struct lock_class *class) = { |
4189 | #define LOCKDEP_STATE(__STATE) \ | |
4190 | __STATE##_verbose, | |
4191 | #include "lockdep_states.h" | |
4192 | #undef LOCKDEP_STATE | |
4193 | }; | |
4194 | ||
4195 | static inline int state_verbose(enum lock_usage_bit bit, | |
4196 | struct lock_class *class) | |
4197 | { | |
c902a1e8 | 4198 | return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class); |
cd95302d PZ |
4199 | } |
4200 | ||
42c50d54 PZ |
4201 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
4202 | enum lock_usage_bit bit, const char *name); | |
4203 | ||
6a6904d3 | 4204 | static int |
1c21f14e PZ |
4205 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
4206 | enum lock_usage_bit new_bit) | |
6a6904d3 | 4207 | { |
f989209e | 4208 | int excl_bit = exclusive_bit(new_bit); |
bba2a8f1 FW |
4209 | int read = new_bit & LOCK_USAGE_READ_MASK; |
4210 | int dir = new_bit & LOCK_USAGE_DIR_MASK; | |
42c50d54 | 4211 | |
38aa2714 PZ |
4212 | /* |
4213 | * Validate that this particular lock does not have conflicting | |
4214 | * usage states. | |
4215 | */ | |
6a6904d3 PZ |
4216 | if (!valid_state(curr, this, new_bit, excl_bit)) |
4217 | return 0; | |
42c50d54 | 4218 | |
38aa2714 | 4219 | /* |
f08e3888 | 4220 | * Check for read in write conflicts |
38aa2714 | 4221 | */ |
f08e3888 BF |
4222 | if (!read && !valid_state(curr, this, new_bit, |
4223 | excl_bit + LOCK_USAGE_READ_MASK)) | |
6a6904d3 | 4224 | return 0; |
780e820b | 4225 | |
f08e3888 | 4226 | |
38aa2714 | 4227 | /* |
f08e3888 BF |
4228 | * Validate that the lock dependencies don't have conflicting usage |
4229 | * states. | |
38aa2714 | 4230 | */ |
f08e3888 BF |
4231 | if (dir) { |
4232 | /* | |
4233 | * mark ENABLED has to look backwards -- to ensure no dependee | |
4234 | * has USED_IN state, which, again, would allow recursion deadlocks. | |
4235 | */ | |
4236 | if (!check_usage_backwards(curr, this, excl_bit)) | |
38aa2714 | 4237 | return 0; |
f08e3888 BF |
4238 | } else { |
4239 | /* | |
4240 | * mark USED_IN has to look forwards -- to ensure no dependency | |
4241 | * has ENABLED state, which would allow recursion deadlocks. | |
4242 | */ | |
4243 | if (!check_usage_forwards(curr, this, excl_bit)) | |
38aa2714 PZ |
4244 | return 0; |
4245 | } | |
780e820b | 4246 | |
cd95302d | 4247 | if (state_verbose(new_bit, hlock_class(this))) |
6a6904d3 PZ |
4248 | return 2; |
4249 | ||
4250 | return 1; | |
4251 | } | |
4252 | ||
fbb9ce95 IM |
4253 | /* |
4254 | * Mark all held locks with a usage bit: | |
4255 | */ | |
1d09daa5 | 4256 | static int |
436a49ae | 4257 | mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit) |
fbb9ce95 | 4258 | { |
fbb9ce95 IM |
4259 | struct held_lock *hlock; |
4260 | int i; | |
4261 | ||
4262 | for (i = 0; i < curr->lockdep_depth; i++) { | |
436a49ae | 4263 | enum lock_usage_bit hlock_bit = base_bit; |
fbb9ce95 IM |
4264 | hlock = curr->held_locks + i; |
4265 | ||
cf2ad4d1 | 4266 | if (hlock->read) |
bba2a8f1 | 4267 | hlock_bit += LOCK_USAGE_READ_MASK; |
cf2ad4d1 | 4268 | |
436a49ae | 4269 | BUG_ON(hlock_bit >= LOCK_USAGE_STATES); |
cf40bd16 | 4270 | |
34d0ed5e | 4271 | if (!hlock->check) |
efbe2eee PZ |
4272 | continue; |
4273 | ||
436a49ae | 4274 | if (!mark_lock(curr, hlock, hlock_bit)) |
fbb9ce95 IM |
4275 | return 0; |
4276 | } | |
4277 | ||
4278 | return 1; | |
4279 | } | |
4280 | ||
fbb9ce95 IM |
4281 | /* |
4282 | * Hardirqs will be enabled: | |
4283 | */ | |
c86e9b98 | 4284 | static void __trace_hardirqs_on_caller(void) |
fbb9ce95 IM |
4285 | { |
4286 | struct task_struct *curr = current; | |
fbb9ce95 | 4287 | |
fbb9ce95 IM |
4288 | /* |
4289 | * We are going to turn hardirqs on, so set the | |
4290 | * usage bit for all held locks: | |
4291 | */ | |
436a49ae | 4292 | if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ)) |
fbb9ce95 IM |
4293 | return; |
4294 | /* | |
4295 | * If we have softirqs enabled, then set the usage | |
4296 | * bit for all held locks. (disabled hardirqs prevented | |
4297 | * this bit from being set before) | |
4298 | */ | |
4299 | if (curr->softirqs_enabled) | |
c86e9b98 | 4300 | mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ); |
8e18257d | 4301 | } |
dd4e5d3a | 4302 | |
c86e9b98 PZ |
4303 | /** |
4304 | * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts | |
c86e9b98 PZ |
4305 | * |
4306 | * Invoked before a possible transition to RCU idle from exit to user or | |
4307 | * guest mode. This ensures that all RCU operations are done before RCU | |
4308 | * stops watching. After the RCU transition lockdep_hardirqs_on() has to be | |
4309 | * invoked to set the final state. | |
4310 | */ | |
8b023acc | 4311 | void lockdep_hardirqs_on_prepare(void) |
dd4e5d3a | 4312 | { |
859d069e PZ |
4313 | if (unlikely(!debug_locks)) |
4314 | return; | |
4315 | ||
4316 | /* | |
4317 | * NMIs do not (and cannot) track lock dependencies, nothing to do. | |
4318 | */ | |
4319 | if (unlikely(in_nmi())) | |
4320 | return; | |
4321 | ||
f8e48a3d | 4322 | if (unlikely(this_cpu_read(lockdep_recursion))) |
dd4e5d3a PZ |
4323 | return; |
4324 | ||
f9ad4a5f | 4325 | if (unlikely(lockdep_hardirqs_enabled())) { |
7d36b26b PZ |
4326 | /* |
4327 | * Neither irq nor preemption are disabled here | |
4328 | * so this is racy by nature but losing one hit | |
4329 | * in a stat is not a big deal. | |
4330 | */ | |
4331 | __debug_atomic_inc(redundant_hardirqs_on); | |
4332 | return; | |
4333 | } | |
4334 | ||
0119fee4 PZ |
4335 | /* |
4336 | * We're enabling irqs and according to our state above irqs weren't | |
4337 | * already enabled, yet we find the hardware thinks they are in fact | |
4338 | * enabled.. someone messed up their IRQ state tracing. | |
4339 | */ | |
dd4e5d3a PZ |
4340 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4341 | return; | |
4342 | ||
0119fee4 PZ |
4343 | /* |
4344 | * See the fine text that goes along with this variable definition. | |
4345 | */ | |
d671002b | 4346 | if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)) |
7d36b26b PZ |
4347 | return; |
4348 | ||
0119fee4 PZ |
4349 | /* |
4350 | * Can't allow enabling interrupts while in an interrupt handler, | |
4351 | * that's general bad form and such. Recursion, limited stack etc.. | |
4352 | */ | |
f9ad4a5f | 4353 | if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context())) |
7d36b26b PZ |
4354 | return; |
4355 | ||
c86e9b98 PZ |
4356 | current->hardirq_chain_key = current->curr_chain_key; |
4357 | ||
4d004099 | 4358 | lockdep_recursion_inc(); |
c86e9b98 | 4359 | __trace_hardirqs_on_caller(); |
10476e63 | 4360 | lockdep_recursion_finish(); |
dd4e5d3a | 4361 | } |
c86e9b98 PZ |
4362 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare); |
4363 | ||
4364 | void noinstr lockdep_hardirqs_on(unsigned long ip) | |
4365 | { | |
0584df9c | 4366 | struct irqtrace_events *trace = ¤t->irqtrace; |
c86e9b98 | 4367 | |
859d069e PZ |
4368 | if (unlikely(!debug_locks)) |
4369 | return; | |
4370 | ||
4371 | /* | |
4372 | * NMIs can happen in the middle of local_irq_{en,dis}able() where the | |
4373 | * tracking state and hardware state are out of sync. | |
4374 | * | |
4375 | * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from, | |
4376 | * and not rely on hardware state like normal interrupts. | |
4377 | */ | |
4378 | if (unlikely(in_nmi())) { | |
ed004953 | 4379 | if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) |
4380 | return; | |
4381 | ||
859d069e PZ |
4382 | /* |
4383 | * Skip: | |
4384 | * - recursion check, because NMI can hit lockdep; | |
4385 | * - hardware state check, because above; | |
4386 | * - chain_key check, see lockdep_hardirqs_on_prepare(). | |
4387 | */ | |
4388 | goto skip_checks; | |
4389 | } | |
c86e9b98 | 4390 | |
f8e48a3d | 4391 | if (unlikely(this_cpu_read(lockdep_recursion))) |
c86e9b98 PZ |
4392 | return; |
4393 | ||
f9ad4a5f | 4394 | if (lockdep_hardirqs_enabled()) { |
c86e9b98 PZ |
4395 | /* |
4396 | * Neither irq nor preemption are disabled here | |
4397 | * so this is racy by nature but losing one hit | |
4398 | * in a stat is not a big deal. | |
4399 | */ | |
4400 | __debug_atomic_inc(redundant_hardirqs_on); | |
4401 | return; | |
4402 | } | |
4403 | ||
4404 | /* | |
4405 | * We're enabling irqs and according to our state above irqs weren't | |
4406 | * already enabled, yet we find the hardware thinks they are in fact | |
4407 | * enabled.. someone messed up their IRQ state tracing. | |
4408 | */ | |
4409 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
4410 | return; | |
4411 | ||
4412 | /* | |
4413 | * Ensure the lock stack remained unchanged between | |
4414 | * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on(). | |
4415 | */ | |
4416 | DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key != | |
4417 | current->curr_chain_key); | |
4418 | ||
859d069e | 4419 | skip_checks: |
c86e9b98 | 4420 | /* we'll do an OFF -> ON transition: */ |
fddf9055 | 4421 | __this_cpu_write(hardirqs_enabled, 1); |
0584df9c ME |
4422 | trace->hardirq_enable_ip = ip; |
4423 | trace->hardirq_enable_event = ++trace->irq_events; | |
c86e9b98 PZ |
4424 | debug_atomic_inc(hardirqs_on_events); |
4425 | } | |
4426 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_on); | |
8e18257d PZ |
4427 | |
4428 | /* | |
4429 | * Hardirqs were disabled: | |
4430 | */ | |
c86e9b98 | 4431 | void noinstr lockdep_hardirqs_off(unsigned long ip) |
8e18257d | 4432 | { |
859d069e PZ |
4433 | if (unlikely(!debug_locks)) |
4434 | return; | |
8e18257d | 4435 | |
859d069e PZ |
4436 | /* |
4437 | * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep; | |
4438 | * they will restore the software state. This ensures the software | |
4439 | * state is consistent inside NMIs as well. | |
4440 | */ | |
ed004953 | 4441 | if (in_nmi()) { |
4442 | if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) | |
4443 | return; | |
4d004099 | 4444 | } else if (__this_cpu_read(lockdep_recursion)) |
8e18257d PZ |
4445 | return; |
4446 | ||
0119fee4 PZ |
4447 | /* |
4448 | * So we're supposed to get called after you mask local IRQs, but for | |
4449 | * some reason the hardware doesn't quite think you did a proper job. | |
4450 | */ | |
8e18257d PZ |
4451 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4452 | return; | |
4453 | ||
f9ad4a5f | 4454 | if (lockdep_hardirqs_enabled()) { |
0584df9c ME |
4455 | struct irqtrace_events *trace = ¤t->irqtrace; |
4456 | ||
8e18257d PZ |
4457 | /* |
4458 | * We have done an ON -> OFF transition: | |
4459 | */ | |
fddf9055 | 4460 | __this_cpu_write(hardirqs_enabled, 0); |
0584df9c ME |
4461 | trace->hardirq_disable_ip = ip; |
4462 | trace->hardirq_disable_event = ++trace->irq_events; | |
bd6d29c2 | 4463 | debug_atomic_inc(hardirqs_off_events); |
c86e9b98 | 4464 | } else { |
bd6d29c2 | 4465 | debug_atomic_inc(redundant_hardirqs_off); |
c86e9b98 | 4466 | } |
8e18257d | 4467 | } |
c86e9b98 | 4468 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_off); |
8e18257d PZ |
4469 | |
4470 | /* | |
4471 | * Softirqs will be enabled: | |
4472 | */ | |
0d38453c | 4473 | void lockdep_softirqs_on(unsigned long ip) |
8e18257d | 4474 | { |
0584df9c | 4475 | struct irqtrace_events *trace = ¤t->irqtrace; |
8e18257d | 4476 | |
4d004099 | 4477 | if (unlikely(!lockdep_enabled())) |
8e18257d PZ |
4478 | return; |
4479 | ||
0119fee4 PZ |
4480 | /* |
4481 | * We fancy IRQs being disabled here, see softirq.c, avoids | |
4482 | * funny state and nesting things. | |
4483 | */ | |
8e18257d PZ |
4484 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4485 | return; | |
4486 | ||
0584df9c | 4487 | if (current->softirqs_enabled) { |
bd6d29c2 | 4488 | debug_atomic_inc(redundant_softirqs_on); |
8e18257d PZ |
4489 | return; |
4490 | } | |
4491 | ||
4d004099 | 4492 | lockdep_recursion_inc(); |
8e18257d PZ |
4493 | /* |
4494 | * We'll do an OFF -> ON transition: | |
4495 | */ | |
0584df9c ME |
4496 | current->softirqs_enabled = 1; |
4497 | trace->softirq_enable_ip = ip; | |
4498 | trace->softirq_enable_event = ++trace->irq_events; | |
bd6d29c2 | 4499 | debug_atomic_inc(softirqs_on_events); |
8e18257d PZ |
4500 | /* |
4501 | * We are going to turn softirqs on, so set the | |
4502 | * usage bit for all held locks, if hardirqs are | |
4503 | * enabled too: | |
4504 | */ | |
f9ad4a5f | 4505 | if (lockdep_hardirqs_enabled()) |
0584df9c | 4506 | mark_held_locks(current, LOCK_ENABLED_SOFTIRQ); |
10476e63 | 4507 | lockdep_recursion_finish(); |
8e18257d PZ |
4508 | } |
4509 | ||
4510 | /* | |
4511 | * Softirqs were disabled: | |
4512 | */ | |
0d38453c | 4513 | void lockdep_softirqs_off(unsigned long ip) |
8e18257d | 4514 | { |
4d004099 | 4515 | if (unlikely(!lockdep_enabled())) |
8e18257d PZ |
4516 | return; |
4517 | ||
0119fee4 PZ |
4518 | /* |
4519 | * We fancy IRQs being disabled here, see softirq.c | |
4520 | */ | |
8e18257d PZ |
4521 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4522 | return; | |
4523 | ||
0584df9c ME |
4524 | if (current->softirqs_enabled) { |
4525 | struct irqtrace_events *trace = ¤t->irqtrace; | |
4526 | ||
8e18257d PZ |
4527 | /* |
4528 | * We have done an ON -> OFF transition: | |
4529 | */ | |
0584df9c ME |
4530 | current->softirqs_enabled = 0; |
4531 | trace->softirq_disable_ip = ip; | |
4532 | trace->softirq_disable_event = ++trace->irq_events; | |
bd6d29c2 | 4533 | debug_atomic_inc(softirqs_off_events); |
0119fee4 PZ |
4534 | /* |
4535 | * Whoops, we wanted softirqs off, so why aren't they? | |
4536 | */ | |
8e18257d PZ |
4537 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
4538 | } else | |
bd6d29c2 | 4539 | debug_atomic_inc(redundant_softirqs_off); |
8e18257d PZ |
4540 | } |
4541 | ||
09180651 YD |
4542 | static int |
4543 | mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) | |
8e18257d | 4544 | { |
09180651 YD |
4545 | if (!check) |
4546 | goto lock_used; | |
4547 | ||
8e18257d PZ |
4548 | /* |
4549 | * If non-trylock use in a hardirq or softirq context, then | |
4550 | * mark the lock as used in these contexts: | |
4551 | */ | |
4552 | if (!hlock->trylock) { | |
4553 | if (hlock->read) { | |
f9ad4a5f | 4554 | if (lockdep_hardirq_context()) |
8e18257d PZ |
4555 | if (!mark_lock(curr, hlock, |
4556 | LOCK_USED_IN_HARDIRQ_READ)) | |
4557 | return 0; | |
4558 | if (curr->softirq_context) | |
4559 | if (!mark_lock(curr, hlock, | |
4560 | LOCK_USED_IN_SOFTIRQ_READ)) | |
4561 | return 0; | |
4562 | } else { | |
f9ad4a5f | 4563 | if (lockdep_hardirq_context()) |
8e18257d PZ |
4564 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) |
4565 | return 0; | |
4566 | if (curr->softirq_context) | |
4567 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) | |
4568 | return 0; | |
4569 | } | |
4570 | } | |
0471db44 BF |
4571 | |
4572 | /* | |
4573 | * For lock_sync(), don't mark the ENABLED usage, since lock_sync() | |
4574 | * creates no critical section and no extra dependency can be introduced | |
4575 | * by interrupts | |
4576 | */ | |
4577 | if (!hlock->hardirqs_off && !hlock->sync) { | |
8e18257d PZ |
4578 | if (hlock->read) { |
4579 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 4580 | LOCK_ENABLED_HARDIRQ_READ)) |
8e18257d PZ |
4581 | return 0; |
4582 | if (curr->softirqs_enabled) | |
4583 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 4584 | LOCK_ENABLED_SOFTIRQ_READ)) |
8e18257d PZ |
4585 | return 0; |
4586 | } else { | |
4587 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 4588 | LOCK_ENABLED_HARDIRQ)) |
8e18257d PZ |
4589 | return 0; |
4590 | if (curr->softirqs_enabled) | |
4591 | if (!mark_lock(curr, hlock, | |
4fc95e86 | 4592 | LOCK_ENABLED_SOFTIRQ)) |
8e18257d PZ |
4593 | return 0; |
4594 | } | |
4595 | } | |
4596 | ||
09180651 YD |
4597 | lock_used: |
4598 | /* mark it as used: */ | |
4599 | if (!mark_lock(curr, hlock, LOCK_USED)) | |
4600 | return 0; | |
4601 | ||
8e18257d PZ |
4602 | return 1; |
4603 | } | |
4604 | ||
c2469756 BF |
4605 | static inline unsigned int task_irq_context(struct task_struct *task) |
4606 | { | |
f9ad4a5f | 4607 | return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() + |
b3b9c187 | 4608 | LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; |
c2469756 BF |
4609 | } |
4610 | ||
8e18257d PZ |
4611 | static int separate_irq_context(struct task_struct *curr, |
4612 | struct held_lock *hlock) | |
4613 | { | |
4614 | unsigned int depth = curr->lockdep_depth; | |
4615 | ||
4616 | /* | |
4617 | * Keep track of points where we cross into an interrupt context: | |
4618 | */ | |
8e18257d PZ |
4619 | if (depth) { |
4620 | struct held_lock *prev_hlock; | |
4621 | ||
4622 | prev_hlock = curr->held_locks + depth-1; | |
4623 | /* | |
4624 | * If we cross into another context, reset the | |
4625 | * hash key (this also prevents the checking and the | |
4626 | * adding of the dependency to 'prev'): | |
4627 | */ | |
4628 | if (prev_hlock->irq_context != hlock->irq_context) | |
4629 | return 1; | |
4630 | } | |
4631 | return 0; | |
fbb9ce95 IM |
4632 | } |
4633 | ||
fbb9ce95 | 4634 | /* |
8e18257d | 4635 | * Mark a lock with a usage bit, and validate the state transition: |
fbb9ce95 | 4636 | */ |
1d09daa5 | 4637 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
0764d23c | 4638 | enum lock_usage_bit new_bit) |
fbb9ce95 | 4639 | { |
2bb8945b | 4640 | unsigned int new_mask, ret = 1; |
fbb9ce95 | 4641 | |
4d56330d YD |
4642 | if (new_bit >= LOCK_USAGE_STATES) { |
4643 | DEBUG_LOCKS_WARN_ON(1); | |
4644 | return 0; | |
4645 | } | |
4646 | ||
23870f12 | 4647 | if (new_bit == LOCK_USED && this->read) |
4648 | new_bit = LOCK_USED_READ; | |
4649 | ||
4650 | new_mask = 1 << new_bit; | |
4651 | ||
fbb9ce95 | 4652 | /* |
8e18257d PZ |
4653 | * If already set then do not dirty the cacheline, |
4654 | * nor do any checks: | |
fbb9ce95 | 4655 | */ |
f82b217e | 4656 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
8e18257d PZ |
4657 | return 1; |
4658 | ||
4659 | if (!graph_lock()) | |
4660 | return 0; | |
fbb9ce95 | 4661 | /* |
25985edc | 4662 | * Make sure we didn't race: |
fbb9ce95 | 4663 | */ |
23870f12 | 4664 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) |
4665 | goto unlock; | |
fbb9ce95 | 4666 | |
1a393408 PZ |
4667 | if (!hlock_class(this)->usage_mask) |
4668 | debug_atomic_dec(nr_unused_locks); | |
4669 | ||
f82b217e | 4670 | hlock_class(this)->usage_mask |= new_mask; |
fbb9ce95 | 4671 | |
2bb8945b PZ |
4672 | if (new_bit < LOCK_TRACE_STATES) { |
4673 | if (!(hlock_class(this)->usage_traces[new_bit] = save_trace())) | |
4674 | return 0; | |
23870f12 | 4675 | } |
fbb9ce95 | 4676 | |
1a393408 | 4677 | if (new_bit < LOCK_USED) { |
2bb8945b PZ |
4678 | ret = mark_lock_irq(curr, this, new_bit); |
4679 | if (!ret) | |
4680 | return 0; | |
8e18257d | 4681 | } |
fbb9ce95 | 4682 | |
23870f12 | 4683 | unlock: |
8e18257d PZ |
4684 | graph_unlock(); |
4685 | ||
4686 | /* | |
4687 | * We must printk outside of the graph_lock: | |
4688 | */ | |
4689 | if (ret == 2) { | |
4690 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
4691 | print_lock(this); | |
4692 | print_irqtrace_events(curr); | |
4693 | dump_stack(); | |
4694 | } | |
4695 | ||
4696 | return ret; | |
4697 | } | |
fbb9ce95 | 4698 | |
9a019db0 PZ |
4699 | static inline short task_wait_context(struct task_struct *curr) |
4700 | { | |
4701 | /* | |
4702 | * Set appropriate wait type for the context; for IRQs we have to take | |
4703 | * into account force_irqthread as that is implied by PREEMPT_RT. | |
4704 | */ | |
f9ad4a5f | 4705 | if (lockdep_hardirq_context()) { |
9a019db0 PZ |
4706 | /* |
4707 | * Check if force_irqthreads will run us threaded. | |
4708 | */ | |
4709 | if (curr->hardirq_threaded || curr->irq_config) | |
4710 | return LD_WAIT_CONFIG; | |
4711 | ||
4712 | return LD_WAIT_SPIN; | |
4713 | } else if (curr->softirq_context) { | |
4714 | /* | |
4715 | * Softirqs are always threaded. | |
4716 | */ | |
4717 | return LD_WAIT_CONFIG; | |
4718 | } | |
4719 | ||
4720 | return LD_WAIT_MAX; | |
4721 | } | |
4722 | ||
de8f5e4f PZ |
4723 | static int |
4724 | print_lock_invalid_wait_context(struct task_struct *curr, | |
4725 | struct held_lock *hlock) | |
4726 | { | |
9a019db0 PZ |
4727 | short curr_inner; |
4728 | ||
de8f5e4f PZ |
4729 | if (!debug_locks_off()) |
4730 | return 0; | |
4731 | if (debug_locks_silent) | |
4732 | return 0; | |
4733 | ||
4734 | pr_warn("\n"); | |
4735 | pr_warn("=============================\n"); | |
4736 | pr_warn("[ BUG: Invalid wait context ]\n"); | |
4737 | print_kernel_ident(); | |
4738 | pr_warn("-----------------------------\n"); | |
4739 | ||
4740 | pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); | |
4741 | print_lock(hlock); | |
4742 | ||
4743 | pr_warn("other info that might help us debug this:\n"); | |
9a019db0 PZ |
4744 | |
4745 | curr_inner = task_wait_context(curr); | |
4746 | pr_warn("context-{%d:%d}\n", curr_inner, curr_inner); | |
4747 | ||
de8f5e4f PZ |
4748 | lockdep_print_held_locks(curr); |
4749 | ||
4750 | pr_warn("stack backtrace:\n"); | |
4751 | dump_stack(); | |
4752 | ||
4753 | return 0; | |
4754 | } | |
4755 | ||
4756 | /* | |
4757 | * Verify the wait_type context. | |
4758 | * | |
a2e05ddd | 4759 | * This check validates we take locks in the right wait-type order; that is it |
de8f5e4f PZ |
4760 | * ensures that we do not take mutexes inside spinlocks and do not attempt to |
4761 | * acquire spinlocks inside raw_spinlocks and the sort. | |
4762 | * | |
4763 | * The entire thing is slightly more complex because of RCU, RCU is a lock that | |
4764 | * can be taken from (pretty much) any context but also has constraints. | |
4765 | * However when taken in a stricter environment the RCU lock does not loosen | |
4766 | * the constraints. | |
4767 | * | |
4768 | * Therefore we must look for the strictest environment in the lock stack and | |
4769 | * compare that to the lock we're trying to acquire. | |
4770 | */ | |
4771 | static int check_wait_context(struct task_struct *curr, struct held_lock *next) | |
4772 | { | |
dfd5e3f5 PZ |
4773 | u8 next_inner = hlock_class(next)->wait_type_inner; |
4774 | u8 next_outer = hlock_class(next)->wait_type_outer; | |
4775 | u8 curr_inner; | |
de8f5e4f PZ |
4776 | int depth; |
4777 | ||
f8b298cc | 4778 | if (!next_inner || next->trylock) |
de8f5e4f PZ |
4779 | return 0; |
4780 | ||
4781 | if (!next_outer) | |
4782 | next_outer = next_inner; | |
4783 | ||
4784 | /* | |
4785 | * Find start of current irq_context.. | |
4786 | */ | |
4787 | for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) { | |
4788 | struct held_lock *prev = curr->held_locks + depth; | |
4789 | if (prev->irq_context != next->irq_context) | |
4790 | break; | |
4791 | } | |
4792 | depth++; | |
4793 | ||
9a019db0 | 4794 | curr_inner = task_wait_context(curr); |
de8f5e4f PZ |
4795 | |
4796 | for (; depth < curr->lockdep_depth; depth++) { | |
4797 | struct held_lock *prev = curr->held_locks + depth; | |
0cce06ba PZ |
4798 | struct lock_class *class = hlock_class(prev); |
4799 | u8 prev_inner = class->wait_type_inner; | |
de8f5e4f PZ |
4800 | |
4801 | if (prev_inner) { | |
4802 | /* | |
4803 | * We can have a bigger inner than a previous one | |
4804 | * when outer is smaller than inner, as with RCU. | |
4805 | * | |
4806 | * Also due to trylocks. | |
4807 | */ | |
4808 | curr_inner = min(curr_inner, prev_inner); | |
0cce06ba PZ |
4809 | |
4810 | /* | |
4811 | * Allow override for annotations -- this is typically | |
4812 | * only valid/needed for code that only exists when | |
4813 | * CONFIG_PREEMPT_RT=n. | |
4814 | */ | |
4815 | if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE)) | |
4816 | curr_inner = prev_inner; | |
de8f5e4f PZ |
4817 | } |
4818 | } | |
4819 | ||
4820 | if (next_outer > curr_inner) | |
4821 | return print_lock_invalid_wait_context(curr, next); | |
4822 | ||
4823 | return 0; | |
4824 | } | |
4825 | ||
30a35f79 | 4826 | #else /* CONFIG_PROVE_LOCKING */ |
886532ae AB |
4827 | |
4828 | static inline int | |
4829 | mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) | |
4830 | { | |
4831 | return 1; | |
4832 | } | |
4833 | ||
4834 | static inline unsigned int task_irq_context(struct task_struct *task) | |
4835 | { | |
4836 | return 0; | |
4837 | } | |
4838 | ||
4839 | static inline int separate_irq_context(struct task_struct *curr, | |
4840 | struct held_lock *hlock) | |
4841 | { | |
4842 | return 0; | |
4843 | } | |
4844 | ||
de8f5e4f PZ |
4845 | static inline int check_wait_context(struct task_struct *curr, |
4846 | struct held_lock *next) | |
4847 | { | |
4848 | return 0; | |
4849 | } | |
4850 | ||
30a35f79 | 4851 | #endif /* CONFIG_PROVE_LOCKING */ |
886532ae | 4852 | |
fbb9ce95 IM |
4853 | /* |
4854 | * Initialize a lock instance's lock-class mapping info: | |
4855 | */ | |
dfd5e3f5 | 4856 | void lockdep_init_map_type(struct lockdep_map *lock, const char *name, |
de8f5e4f | 4857 | struct lock_class_key *key, int subclass, |
dfd5e3f5 | 4858 | u8 inner, u8 outer, u8 lock_type) |
fbb9ce95 | 4859 | { |
d3d03d4f YZ |
4860 | int i; |
4861 | ||
d3d03d4f YZ |
4862 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
4863 | lock->class_cache[i] = NULL; | |
62016250 | 4864 | |
c8a25005 PZ |
4865 | #ifdef CONFIG_LOCK_STAT |
4866 | lock->cpu = raw_smp_processor_id(); | |
4867 | #endif | |
4868 | ||
0119fee4 PZ |
4869 | /* |
4870 | * Can't be having no nameless bastards around this place! | |
4871 | */ | |
c8a25005 PZ |
4872 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
4873 | lock->name = "NULL"; | |
fbb9ce95 | 4874 | return; |
c8a25005 PZ |
4875 | } |
4876 | ||
4877 | lock->name = name; | |
fbb9ce95 | 4878 | |
de8f5e4f PZ |
4879 | lock->wait_type_outer = outer; |
4880 | lock->wait_type_inner = inner; | |
dfd5e3f5 | 4881 | lock->lock_type = lock_type; |
de8f5e4f | 4882 | |
0119fee4 PZ |
4883 | /* |
4884 | * No key, no joy, we need to hash something. | |
4885 | */ | |
fbb9ce95 IM |
4886 | if (DEBUG_LOCKS_WARN_ON(!key)) |
4887 | return; | |
fbb9ce95 | 4888 | /* |
108c1485 BVA |
4889 | * Sanity check, the lock-class key must either have been allocated |
4890 | * statically or must have been registered as a dynamic key. | |
fbb9ce95 | 4891 | */ |
108c1485 BVA |
4892 | if (!static_obj(key) && !is_dynamic_key(key)) { |
4893 | if (debug_locks) | |
4894 | printk(KERN_ERR "BUG: key %px has not been registered!\n", key); | |
fbb9ce95 IM |
4895 | DEBUG_LOCKS_WARN_ON(1); |
4896 | return; | |
4897 | } | |
fbb9ce95 | 4898 | lock->key = key; |
c8a25005 PZ |
4899 | |
4900 | if (unlikely(!debug_locks)) | |
4901 | return; | |
4902 | ||
35a9393c PZ |
4903 | if (subclass) { |
4904 | unsigned long flags; | |
4905 | ||
4d004099 | 4906 | if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled())) |
35a9393c PZ |
4907 | return; |
4908 | ||
4909 | raw_local_irq_save(flags); | |
4d004099 | 4910 | lockdep_recursion_inc(); |
4dfbb9d8 | 4911 | register_lock_class(lock, subclass, 1); |
10476e63 | 4912 | lockdep_recursion_finish(); |
35a9393c PZ |
4913 | raw_local_irq_restore(flags); |
4914 | } | |
fbb9ce95 | 4915 | } |
dfd5e3f5 | 4916 | EXPORT_SYMBOL_GPL(lockdep_init_map_type); |
fbb9ce95 | 4917 | |
1704f47b | 4918 | struct lock_class_key __lockdep_no_validate__; |
ea6749c7 | 4919 | EXPORT_SYMBOL_GPL(__lockdep_no_validate__); |
1704f47b | 4920 | |
eb1cfd09 KO |
4921 | #ifdef CONFIG_PROVE_LOCKING |
4922 | void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn, | |
4923 | lock_print_fn print_fn) | |
4924 | { | |
4925 | struct lock_class *class = lock->class_cache[0]; | |
4926 | unsigned long flags; | |
4927 | ||
4928 | raw_local_irq_save(flags); | |
4929 | lockdep_recursion_inc(); | |
4930 | ||
4931 | if (!class) | |
4932 | class = register_lock_class(lock, 0, 0); | |
4933 | ||
4934 | if (class) { | |
4935 | WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn); | |
4936 | WARN_ON(class->print_fn && class->print_fn != print_fn); | |
4937 | ||
4938 | class->cmp_fn = cmp_fn; | |
4939 | class->print_fn = print_fn; | |
4940 | } | |
4941 | ||
4942 | lockdep_recursion_finish(); | |
4943 | raw_local_irq_restore(flags); | |
4944 | } | |
4945 | EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn); | |
4946 | #endif | |
4947 | ||
f7c1c6b3 | 4948 | static void |
d0945950 | 4949 | print_lock_nested_lock_not_held(struct task_struct *curr, |
8b023acc | 4950 | struct held_lock *hlock) |
d0945950 ML |
4951 | { |
4952 | if (!debug_locks_off()) | |
f7c1c6b3 | 4953 | return; |
d0945950 | 4954 | if (debug_locks_silent) |
f7c1c6b3 | 4955 | return; |
d0945950 | 4956 | |
681fbec8 | 4957 | pr_warn("\n"); |
a5dd63ef PM |
4958 | pr_warn("==================================\n"); |
4959 | pr_warn("WARNING: Nested lock was not taken\n"); | |
d0945950 | 4960 | print_kernel_ident(); |
a5dd63ef | 4961 | pr_warn("----------------------------------\n"); |
d0945950 | 4962 | |
681fbec8 | 4963 | pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); |
d0945950 ML |
4964 | print_lock(hlock); |
4965 | ||
681fbec8 PM |
4966 | pr_warn("\nbut this task is not holding:\n"); |
4967 | pr_warn("%s\n", hlock->nest_lock->name); | |
d0945950 | 4968 | |
681fbec8 | 4969 | pr_warn("\nstack backtrace:\n"); |
d0945950 ML |
4970 | dump_stack(); |
4971 | ||
681fbec8 | 4972 | pr_warn("\nother info that might help us debug this:\n"); |
d0945950 ML |
4973 | lockdep_print_held_locks(curr); |
4974 | ||
681fbec8 | 4975 | pr_warn("\nstack backtrace:\n"); |
d0945950 | 4976 | dump_stack(); |
d0945950 ML |
4977 | } |
4978 | ||
08f36ff6 | 4979 | static int __lock_is_held(const struct lockdep_map *lock, int read); |
d0945950 | 4980 | |
fbb9ce95 IM |
4981 | /* |
4982 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
4983 | * We maintain the dependency maps and validate the locking attempt: | |
8ee10862 WL |
4984 | * |
4985 | * The callers must make sure that IRQs are disabled before calling it, | |
4986 | * otherwise we could get an interrupt which would want to take locks, | |
4987 | * which would end up in lockdep again. | |
fbb9ce95 IM |
4988 | */ |
4989 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
4990 | int trylock, int read, int check, int hardirqs_off, | |
bb97a91e | 4991 | struct lockdep_map *nest_lock, unsigned long ip, |
0471db44 | 4992 | int references, int pin_count, int sync) |
fbb9ce95 IM |
4993 | { |
4994 | struct task_struct *curr = current; | |
d6d897ce | 4995 | struct lock_class *class = NULL; |
fbb9ce95 | 4996 | struct held_lock *hlock; |
5f18ab5c | 4997 | unsigned int depth; |
fbb9ce95 | 4998 | int chain_head = 0; |
bb97a91e | 4999 | int class_idx; |
fbb9ce95 IM |
5000 | u64 chain_key; |
5001 | ||
5002 | if (unlikely(!debug_locks)) | |
5003 | return 0; | |
5004 | ||
fb9edbe9 ON |
5005 | if (!prove_locking || lock->key == &__lockdep_no_validate__) |
5006 | check = 0; | |
1704f47b | 5007 | |
62016250 HM |
5008 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
5009 | class = lock->class_cache[subclass]; | |
d6d897ce | 5010 | /* |
62016250 | 5011 | * Not cached? |
d6d897ce | 5012 | */ |
fbb9ce95 | 5013 | if (unlikely(!class)) { |
4dfbb9d8 | 5014 | class = register_lock_class(lock, subclass, 0); |
fbb9ce95 IM |
5015 | if (!class) |
5016 | return 0; | |
5017 | } | |
8ca2b56c WL |
5018 | |
5019 | debug_class_ops_inc(class); | |
5020 | ||
fbb9ce95 | 5021 | if (very_verbose(class)) { |
04860d48 | 5022 | printk("\nacquire class [%px] %s", class->key, class->name); |
fbb9ce95 | 5023 | if (class->name_version > 1) |
f943fe0f DV |
5024 | printk(KERN_CONT "#%d", class->name_version); |
5025 | printk(KERN_CONT "\n"); | |
fbb9ce95 IM |
5026 | dump_stack(); |
5027 | } | |
5028 | ||
5029 | /* | |
5030 | * Add the lock to the list of currently held locks. | |
5031 | * (we dont increase the depth just yet, up until the | |
5032 | * dependency checks are done) | |
5033 | */ | |
5034 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
5035 | /* |
5036 | * Ran out of static storage for our per-task lock stack again have we? | |
5037 | */ | |
fbb9ce95 IM |
5038 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
5039 | return 0; | |
5040 | ||
01bb6f0a | 5041 | class_idx = class - lock_classes; |
bb97a91e | 5042 | |
0471db44 BF |
5043 | if (depth && !sync) { |
5044 | /* we're holding locks and the new held lock is not a sync */ | |
bb97a91e PZ |
5045 | hlock = curr->held_locks + depth - 1; |
5046 | if (hlock->class_idx == class_idx && nest_lock) { | |
d9349850 ID |
5047 | if (!references) |
5048 | references++; | |
7fb4a2ce | 5049 | |
d9349850 | 5050 | if (!hlock->references) |
bb97a91e | 5051 | hlock->references++; |
d9349850 ID |
5052 | |
5053 | hlock->references += references; | |
5054 | ||
5055 | /* Overflow */ | |
5056 | if (DEBUG_LOCKS_WARN_ON(hlock->references < references)) | |
5057 | return 0; | |
bb97a91e | 5058 | |
8c8889d8 | 5059 | return 2; |
bb97a91e PZ |
5060 | } |
5061 | } | |
5062 | ||
fbb9ce95 | 5063 | hlock = curr->held_locks + depth; |
0119fee4 PZ |
5064 | /* |
5065 | * Plain impossible, we just registered it and checked it weren't no | |
5066 | * NULL like.. I bet this mushroom I ate was good! | |
5067 | */ | |
f82b217e DJ |
5068 | if (DEBUG_LOCKS_WARN_ON(!class)) |
5069 | return 0; | |
bb97a91e | 5070 | hlock->class_idx = class_idx; |
fbb9ce95 IM |
5071 | hlock->acquire_ip = ip; |
5072 | hlock->instance = lock; | |
7531e2f3 | 5073 | hlock->nest_lock = nest_lock; |
c2469756 | 5074 | hlock->irq_context = task_irq_context(curr); |
fbb9ce95 IM |
5075 | hlock->trylock = trylock; |
5076 | hlock->read = read; | |
5077 | hlock->check = check; | |
0471db44 | 5078 | hlock->sync = !!sync; |
6951b12a | 5079 | hlock->hardirqs_off = !!hardirqs_off; |
bb97a91e | 5080 | hlock->references = references; |
f20786ff PZ |
5081 | #ifdef CONFIG_LOCK_STAT |
5082 | hlock->waittime_stamp = 0; | |
3365e779 | 5083 | hlock->holdtime_stamp = lockstat_clock(); |
f20786ff | 5084 | #endif |
21199f27 | 5085 | hlock->pin_count = pin_count; |
fbb9ce95 | 5086 | |
de8f5e4f PZ |
5087 | if (check_wait_context(curr, hlock)) |
5088 | return 0; | |
5089 | ||
09180651 YD |
5090 | /* Initialize the lock usage bit */ |
5091 | if (!mark_usage(curr, hlock, check)) | |
fbb9ce95 | 5092 | return 0; |
8e18257d | 5093 | |
fbb9ce95 | 5094 | /* |
17aacfb9 | 5095 | * Calculate the chain hash: it's the combined hash of all the |
fbb9ce95 IM |
5096 | * lock keys along the dependency chain. We save the hash value |
5097 | * at every step so that we can get the current hash easily | |
5098 | * after unlock. The chain hash is then used to cache dependency | |
5099 | * results. | |
5100 | * | |
5101 | * The 'key ID' is what is the most compact key value to drive | |
5102 | * the hash, not class->key. | |
5103 | */ | |
0119fee4 | 5104 | /* |
01bb6f0a | 5105 | * Whoops, we did it again.. class_idx is invalid. |
0119fee4 | 5106 | */ |
01bb6f0a | 5107 | if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use))) |
fbb9ce95 IM |
5108 | return 0; |
5109 | ||
5110 | chain_key = curr->curr_chain_key; | |
5111 | if (!depth) { | |
0119fee4 PZ |
5112 | /* |
5113 | * How can we have a chain hash when we ain't got no keys?! | |
5114 | */ | |
f6ec8829 | 5115 | if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY)) |
fbb9ce95 IM |
5116 | return 0; |
5117 | chain_head = 1; | |
5118 | } | |
5119 | ||
5120 | hlock->prev_chain_key = chain_key; | |
8e18257d | 5121 | if (separate_irq_context(curr, hlock)) { |
f6ec8829 | 5122 | chain_key = INITIAL_CHAIN_KEY; |
8e18257d | 5123 | chain_head = 1; |
fbb9ce95 | 5124 | } |
f611e8cf | 5125 | chain_key = iterate_chain_key(chain_key, hlock_id(hlock)); |
fbb9ce95 | 5126 | |
f7c1c6b3 | 5127 | if (nest_lock && !__lock_is_held(nest_lock, -1)) { |
8b023acc | 5128 | print_lock_nested_lock_not_held(curr, hlock); |
f7c1c6b3 YD |
5129 | return 0; |
5130 | } | |
d0945950 | 5131 | |
a0b0fd53 BVA |
5132 | if (!debug_locks_silent) { |
5133 | WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key); | |
5134 | WARN_ON_ONCE(!hlock_class(hlock)->key); | |
5135 | } | |
5136 | ||
0b9fc8ec | 5137 | if (!validate_chain(curr, hlock, chain_head, chain_key)) |
8e18257d | 5138 | return 0; |
381a2292 | 5139 | |
0471db44 BF |
5140 | /* For lock_sync(), we are done here since no actual critical section */ |
5141 | if (hlock->sync) | |
5142 | return 1; | |
5143 | ||
3aa416b0 | 5144 | curr->curr_chain_key = chain_key; |
fbb9ce95 IM |
5145 | curr->lockdep_depth++; |
5146 | check_chain_key(curr); | |
60e114d1 JP |
5147 | #ifdef CONFIG_DEBUG_LOCKDEP |
5148 | if (unlikely(!debug_locks)) | |
5149 | return 0; | |
5150 | #endif | |
fbb9ce95 IM |
5151 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
5152 | debug_locks_off(); | |
2c522836 DJ |
5153 | print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); |
5154 | printk(KERN_DEBUG "depth: %i max: %lu!\n", | |
c0540606 | 5155 | curr->lockdep_depth, MAX_LOCK_DEPTH); |
c0540606 BG |
5156 | |
5157 | lockdep_print_held_locks(current); | |
5158 | debug_show_all_locks(); | |
eedeeabd | 5159 | dump_stack(); |
c0540606 | 5160 | |
fbb9ce95 IM |
5161 | return 0; |
5162 | } | |
381a2292 | 5163 | |
fbb9ce95 IM |
5164 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
5165 | max_lockdep_depth = curr->lockdep_depth; | |
5166 | ||
5167 | return 1; | |
5168 | } | |
5169 | ||
f7c1c6b3 YD |
5170 | static void print_unlock_imbalance_bug(struct task_struct *curr, |
5171 | struct lockdep_map *lock, | |
5172 | unsigned long ip) | |
fbb9ce95 IM |
5173 | { |
5174 | if (!debug_locks_off()) | |
f7c1c6b3 | 5175 | return; |
fbb9ce95 | 5176 | if (debug_locks_silent) |
f7c1c6b3 | 5177 | return; |
fbb9ce95 | 5178 | |
681fbec8 | 5179 | pr_warn("\n"); |
a5dd63ef PM |
5180 | pr_warn("=====================================\n"); |
5181 | pr_warn("WARNING: bad unlock balance detected!\n"); | |
fbdc4b9a | 5182 | print_kernel_ident(); |
a5dd63ef | 5183 | pr_warn("-------------------------------------\n"); |
681fbec8 | 5184 | pr_warn("%s/%d is trying to release lock (", |
ba25f9dc | 5185 | curr->comm, task_pid_nr(curr)); |
fbb9ce95 | 5186 | print_lockdep_cache(lock); |
681fbec8 | 5187 | pr_cont(") at:\n"); |
2062a4e8 | 5188 | print_ip_sym(KERN_WARNING, ip); |
681fbec8 PM |
5189 | pr_warn("but there are no more locks to release!\n"); |
5190 | pr_warn("\nother info that might help us debug this:\n"); | |
fbb9ce95 IM |
5191 | lockdep_print_held_locks(curr); |
5192 | ||
681fbec8 | 5193 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 | 5194 | dump_stack(); |
fbb9ce95 IM |
5195 | } |
5196 | ||
c86e9b98 PZ |
5197 | static noinstr int match_held_lock(const struct held_lock *hlock, |
5198 | const struct lockdep_map *lock) | |
bb97a91e PZ |
5199 | { |
5200 | if (hlock->instance == lock) | |
5201 | return 1; | |
5202 | ||
5203 | if (hlock->references) { | |
08f36ff6 | 5204 | const struct lock_class *class = lock->class_cache[0]; |
bb97a91e PZ |
5205 | |
5206 | if (!class) | |
5207 | class = look_up_lock_class(lock, 0); | |
5208 | ||
80e0401e PZ |
5209 | /* |
5210 | * If look_up_lock_class() failed to find a class, we're trying | |
5211 | * to test if we hold a lock that has never yet been acquired. | |
5212 | * Clearly if the lock hasn't been acquired _ever_, we're not | |
5213 | * holding it either, so report failure. | |
5214 | */ | |
64f29d1b | 5215 | if (!class) |
bb97a91e PZ |
5216 | return 0; |
5217 | ||
0119fee4 PZ |
5218 | /* |
5219 | * References, but not a lock we're actually ref-counting? | |
5220 | * State got messed up, follow the sites that change ->references | |
5221 | * and try to make sense of it. | |
5222 | */ | |
bb97a91e PZ |
5223 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
5224 | return 0; | |
5225 | ||
01bb6f0a | 5226 | if (hlock->class_idx == class - lock_classes) |
bb97a91e PZ |
5227 | return 1; |
5228 | } | |
5229 | ||
5230 | return 0; | |
5231 | } | |
5232 | ||
41c2c5b8 O |
5233 | /* @depth must not be zero */ |
5234 | static struct held_lock *find_held_lock(struct task_struct *curr, | |
5235 | struct lockdep_map *lock, | |
5236 | unsigned int depth, int *idx) | |
5237 | { | |
5238 | struct held_lock *ret, *hlock, *prev_hlock; | |
5239 | int i; | |
5240 | ||
5241 | i = depth - 1; | |
5242 | hlock = curr->held_locks + i; | |
5243 | ret = hlock; | |
5244 | if (match_held_lock(hlock, lock)) | |
5245 | goto out; | |
5246 | ||
5247 | ret = NULL; | |
5248 | for (i--, prev_hlock = hlock--; | |
5249 | i >= 0; | |
5250 | i--, prev_hlock = hlock--) { | |
5251 | /* | |
5252 | * We must not cross into another context: | |
5253 | */ | |
5254 | if (prev_hlock->irq_context != hlock->irq_context) { | |
5255 | ret = NULL; | |
5256 | break; | |
5257 | } | |
5258 | if (match_held_lock(hlock, lock)) { | |
5259 | ret = hlock; | |
5260 | break; | |
5261 | } | |
5262 | } | |
5263 | ||
5264 | out: | |
5265 | *idx = i; | |
5266 | return ret; | |
5267 | } | |
5268 | ||
e969970b | 5269 | static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, |
8c8889d8 | 5270 | int idx, unsigned int *merged) |
e969970b O |
5271 | { |
5272 | struct held_lock *hlock; | |
8c8889d8 | 5273 | int first_idx = idx; |
e969970b | 5274 | |
8ee10862 WL |
5275 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
5276 | return 0; | |
5277 | ||
e969970b | 5278 | for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { |
8c8889d8 | 5279 | switch (__lock_acquire(hlock->instance, |
e969970b O |
5280 | hlock_class(hlock)->subclass, |
5281 | hlock->trylock, | |
5282 | hlock->read, hlock->check, | |
5283 | hlock->hardirqs_off, | |
5284 | hlock->nest_lock, hlock->acquire_ip, | |
0471db44 | 5285 | hlock->references, hlock->pin_count, 0)) { |
8c8889d8 | 5286 | case 0: |
e969970b | 5287 | return 1; |
8c8889d8 ID |
5288 | case 1: |
5289 | break; | |
5290 | case 2: | |
5291 | *merged += (idx == first_idx); | |
5292 | break; | |
5293 | default: | |
5294 | WARN_ON(1); | |
5295 | return 0; | |
5296 | } | |
e969970b O |
5297 | } |
5298 | return 0; | |
5299 | } | |
5300 | ||
64aa348e | 5301 | static int |
00ef9f73 PZ |
5302 | __lock_set_class(struct lockdep_map *lock, const char *name, |
5303 | struct lock_class_key *key, unsigned int subclass, | |
5304 | unsigned long ip) | |
64aa348e PZ |
5305 | { |
5306 | struct task_struct *curr = current; | |
8c8889d8 | 5307 | unsigned int depth, merged = 0; |
41c2c5b8 | 5308 | struct held_lock *hlock; |
64aa348e | 5309 | struct lock_class *class; |
64aa348e PZ |
5310 | int i; |
5311 | ||
513e1073 WL |
5312 | if (unlikely(!debug_locks)) |
5313 | return 0; | |
5314 | ||
64aa348e | 5315 | depth = curr->lockdep_depth; |
0119fee4 PZ |
5316 | /* |
5317 | * This function is about (re)setting the class of a held lock, | |
5318 | * yet we're not actually holding any locks. Naughty user! | |
5319 | */ | |
64aa348e PZ |
5320 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5321 | return 0; | |
5322 | ||
41c2c5b8 | 5323 | hlock = find_held_lock(curr, lock, depth, &i); |
f7c1c6b3 YD |
5324 | if (!hlock) { |
5325 | print_unlock_imbalance_bug(curr, lock, ip); | |
5326 | return 0; | |
5327 | } | |
64aa348e | 5328 | |
eae6d58d PZ |
5329 | lockdep_init_map_type(lock, name, key, 0, |
5330 | lock->wait_type_inner, | |
5331 | lock->wait_type_outer, | |
5332 | lock->lock_type); | |
64aa348e | 5333 | class = register_lock_class(lock, subclass, 0); |
01bb6f0a | 5334 | hlock->class_idx = class - lock_classes; |
64aa348e PZ |
5335 | |
5336 | curr->lockdep_depth = i; | |
5337 | curr->curr_chain_key = hlock->prev_chain_key; | |
5338 | ||
8c8889d8 | 5339 | if (reacquire_held_locks(curr, depth, i, &merged)) |
e969970b | 5340 | return 0; |
64aa348e | 5341 | |
0119fee4 PZ |
5342 | /* |
5343 | * I took it apart and put it back together again, except now I have | |
5344 | * these 'spare' parts.. where shall I put them. | |
5345 | */ | |
8c8889d8 | 5346 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged)) |
64aa348e PZ |
5347 | return 0; |
5348 | return 1; | |
5349 | } | |
5350 | ||
6419c4af O |
5351 | static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
5352 | { | |
5353 | struct task_struct *curr = current; | |
8c8889d8 | 5354 | unsigned int depth, merged = 0; |
6419c4af | 5355 | struct held_lock *hlock; |
6419c4af O |
5356 | int i; |
5357 | ||
71492580 WL |
5358 | if (unlikely(!debug_locks)) |
5359 | return 0; | |
5360 | ||
6419c4af O |
5361 | depth = curr->lockdep_depth; |
5362 | /* | |
5363 | * This function is about (re)setting the class of a held lock, | |
5364 | * yet we're not actually holding any locks. Naughty user! | |
5365 | */ | |
5366 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
5367 | return 0; | |
5368 | ||
5369 | hlock = find_held_lock(curr, lock, depth, &i); | |
f7c1c6b3 YD |
5370 | if (!hlock) { |
5371 | print_unlock_imbalance_bug(curr, lock, ip); | |
5372 | return 0; | |
5373 | } | |
6419c4af O |
5374 | |
5375 | curr->lockdep_depth = i; | |
5376 | curr->curr_chain_key = hlock->prev_chain_key; | |
5377 | ||
5378 | WARN(hlock->read, "downgrading a read lock"); | |
5379 | hlock->read = 1; | |
5380 | hlock->acquire_ip = ip; | |
5381 | ||
8c8889d8 ID |
5382 | if (reacquire_held_locks(curr, depth, i, &merged)) |
5383 | return 0; | |
5384 | ||
5385 | /* Merging can't happen with unchanged classes.. */ | |
5386 | if (DEBUG_LOCKS_WARN_ON(merged)) | |
6419c4af O |
5387 | return 0; |
5388 | ||
5389 | /* | |
5390 | * I took it apart and put it back together again, except now I have | |
5391 | * these 'spare' parts.. where shall I put them. | |
5392 | */ | |
5393 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) | |
5394 | return 0; | |
8c8889d8 | 5395 | |
6419c4af O |
5396 | return 1; |
5397 | } | |
5398 | ||
fbb9ce95 | 5399 | /* |
c759bc47 | 5400 | * Remove the lock from the list of currently held locks - this gets |
e0f56fd7 PZ |
5401 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
5402 | * mutex_lock_interruptible()). | |
fbb9ce95 IM |
5403 | */ |
5404 | static int | |
b4adfe8e | 5405 | __lock_release(struct lockdep_map *lock, unsigned long ip) |
fbb9ce95 | 5406 | { |
e0f56fd7 | 5407 | struct task_struct *curr = current; |
8c8889d8 | 5408 | unsigned int depth, merged = 1; |
41c2c5b8 | 5409 | struct held_lock *hlock; |
e966eaee | 5410 | int i; |
fbb9ce95 | 5411 | |
e0f56fd7 PZ |
5412 | if (unlikely(!debug_locks)) |
5413 | return 0; | |
5414 | ||
fbb9ce95 | 5415 | depth = curr->lockdep_depth; |
0119fee4 PZ |
5416 | /* |
5417 | * So we're all set to release this lock.. wait what lock? We don't | |
5418 | * own any locks, you've been drinking again? | |
5419 | */ | |
dd471efe | 5420 | if (depth <= 0) { |
f7c1c6b3 YD |
5421 | print_unlock_imbalance_bug(curr, lock, ip); |
5422 | return 0; | |
5423 | } | |
fbb9ce95 | 5424 | |
e0f56fd7 PZ |
5425 | /* |
5426 | * Check whether the lock exists in the current stack | |
5427 | * of held locks: | |
5428 | */ | |
41c2c5b8 | 5429 | hlock = find_held_lock(curr, lock, depth, &i); |
f7c1c6b3 YD |
5430 | if (!hlock) { |
5431 | print_unlock_imbalance_bug(curr, lock, ip); | |
5432 | return 0; | |
5433 | } | |
fbb9ce95 | 5434 | |
bb97a91e PZ |
5435 | if (hlock->instance == lock) |
5436 | lock_release_holdtime(hlock); | |
5437 | ||
a24fc60d PZ |
5438 | WARN(hlock->pin_count, "releasing a pinned lock\n"); |
5439 | ||
bb97a91e PZ |
5440 | if (hlock->references) { |
5441 | hlock->references--; | |
5442 | if (hlock->references) { | |
5443 | /* | |
5444 | * We had, and after removing one, still have | |
5445 | * references, the current lock stack is still | |
5446 | * valid. We're done! | |
5447 | */ | |
5448 | return 1; | |
5449 | } | |
5450 | } | |
f20786ff | 5451 | |
fbb9ce95 IM |
5452 | /* |
5453 | * We have the right lock to unlock, 'hlock' points to it. | |
5454 | * Now we remove it from the stack, and add back the other | |
5455 | * entries (if any), recalculating the hash along the way: | |
5456 | */ | |
bb97a91e | 5457 | |
fbb9ce95 IM |
5458 | curr->lockdep_depth = i; |
5459 | curr->curr_chain_key = hlock->prev_chain_key; | |
5460 | ||
ce52a18d WL |
5461 | /* |
5462 | * The most likely case is when the unlock is on the innermost | |
5463 | * lock. In this case, we are done! | |
5464 | */ | |
5465 | if (i == depth-1) | |
5466 | return 1; | |
5467 | ||
8c8889d8 | 5468 | if (reacquire_held_locks(curr, depth, i + 1, &merged)) |
e969970b | 5469 | return 0; |
fbb9ce95 | 5470 | |
0119fee4 PZ |
5471 | /* |
5472 | * We had N bottles of beer on the wall, we drank one, but now | |
5473 | * there's not N-1 bottles of beer left on the wall... | |
8c8889d8 | 5474 | * Pouring two of the bottles together is acceptable. |
0119fee4 | 5475 | */ |
8c8889d8 | 5476 | DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged); |
f20786ff | 5477 | |
ce52a18d WL |
5478 | /* |
5479 | * Since reacquire_held_locks() would have called check_chain_key() | |
5480 | * indirectly via __lock_acquire(), we don't need to do it again | |
5481 | * on return. | |
5482 | */ | |
5483 | return 0; | |
fbb9ce95 IM |
5484 | } |
5485 | ||
c86e9b98 | 5486 | static __always_inline |
2f43c602 | 5487 | int __lock_is_held(const struct lockdep_map *lock, int read) |
fbb9ce95 | 5488 | { |
f607c668 PZ |
5489 | struct task_struct *curr = current; |
5490 | int i; | |
fbb9ce95 | 5491 | |
f607c668 | 5492 | for (i = 0; i < curr->lockdep_depth; i++) { |
bb97a91e | 5493 | struct held_lock *hlock = curr->held_locks + i; |
fbb9ce95 | 5494 | |
f8319483 | 5495 | if (match_held_lock(hlock, lock)) { |
2507003a | 5496 | if (read == -1 || !!hlock->read == read) |
f8cfa466 | 5497 | return LOCK_STATE_HELD; |
f8319483 | 5498 | |
f8cfa466 | 5499 | return LOCK_STATE_NOT_HELD; |
f8319483 | 5500 | } |
f607c668 | 5501 | } |
f20786ff | 5502 | |
f8cfa466 | 5503 | return LOCK_STATE_NOT_HELD; |
fbb9ce95 IM |
5504 | } |
5505 | ||
e7904a28 PZ |
5506 | static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) |
5507 | { | |
5508 | struct pin_cookie cookie = NIL_COOKIE; | |
5509 | struct task_struct *curr = current; | |
5510 | int i; | |
5511 | ||
5512 | if (unlikely(!debug_locks)) | |
5513 | return cookie; | |
5514 | ||
5515 | for (i = 0; i < curr->lockdep_depth; i++) { | |
5516 | struct held_lock *hlock = curr->held_locks + i; | |
5517 | ||
5518 | if (match_held_lock(hlock, lock)) { | |
5519 | /* | |
5520 | * Grab 16bits of randomness; this is sufficient to not | |
5521 | * be guessable and still allows some pin nesting in | |
5522 | * our u32 pin_count. | |
5523 | */ | |
4051a817 | 5524 | cookie.val = 1 + (sched_clock() & 0xffff); |
e7904a28 PZ |
5525 | hlock->pin_count += cookie.val; |
5526 | return cookie; | |
5527 | } | |
5528 | } | |
5529 | ||
5530 | WARN(1, "pinning an unheld lock\n"); | |
5531 | return cookie; | |
5532 | } | |
5533 | ||
5534 | static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) | |
fbb9ce95 IM |
5535 | { |
5536 | struct task_struct *curr = current; | |
a24fc60d | 5537 | int i; |
fbb9ce95 | 5538 | |
a24fc60d | 5539 | if (unlikely(!debug_locks)) |
fbb9ce95 IM |
5540 | return; |
5541 | ||
a24fc60d PZ |
5542 | for (i = 0; i < curr->lockdep_depth; i++) { |
5543 | struct held_lock *hlock = curr->held_locks + i; | |
5544 | ||
5545 | if (match_held_lock(hlock, lock)) { | |
e7904a28 | 5546 | hlock->pin_count += cookie.val; |
fbb9ce95 | 5547 | return; |
a24fc60d | 5548 | } |
fbb9ce95 IM |
5549 | } |
5550 | ||
a24fc60d | 5551 | WARN(1, "pinning an unheld lock\n"); |
fbb9ce95 IM |
5552 | } |
5553 | ||
e7904a28 | 5554 | static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
f607c668 PZ |
5555 | { |
5556 | struct task_struct *curr = current; | |
5557 | int i; | |
5558 | ||
a24fc60d PZ |
5559 | if (unlikely(!debug_locks)) |
5560 | return; | |
5561 | ||
f607c668 | 5562 | for (i = 0; i < curr->lockdep_depth; i++) { |
bb97a91e PZ |
5563 | struct held_lock *hlock = curr->held_locks + i; |
5564 | ||
a24fc60d PZ |
5565 | if (match_held_lock(hlock, lock)) { |
5566 | if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n")) | |
5567 | return; | |
5568 | ||
e7904a28 PZ |
5569 | hlock->pin_count -= cookie.val; |
5570 | ||
5571 | if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n")) | |
5572 | hlock->pin_count = 0; | |
5573 | ||
a24fc60d PZ |
5574 | return; |
5575 | } | |
f607c668 PZ |
5576 | } |
5577 | ||
a24fc60d | 5578 | WARN(1, "unpinning an unheld lock\n"); |
f607c668 PZ |
5579 | } |
5580 | ||
fbb9ce95 IM |
5581 | /* |
5582 | * Check whether we follow the irq-flags state precisely: | |
5583 | */ | |
77ca93a6 | 5584 | static noinstr void check_flags(unsigned long flags) |
fbb9ce95 | 5585 | { |
30a35f79 | 5586 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) |
fbb9ce95 IM |
5587 | if (!debug_locks) |
5588 | return; | |
5589 | ||
77ca93a6 PZ |
5590 | /* Get the warning out.. */ |
5591 | instrumentation_begin(); | |
5592 | ||
5f9fa8a6 | 5593 | if (irqs_disabled_flags(flags)) { |
f9ad4a5f | 5594 | if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) { |
5f9fa8a6 IM |
5595 | printk("possible reason: unannotated irqs-off.\n"); |
5596 | } | |
5597 | } else { | |
f9ad4a5f | 5598 | if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) { |
5f9fa8a6 IM |
5599 | printk("possible reason: unannotated irqs-on.\n"); |
5600 | } | |
5601 | } | |
fbb9ce95 | 5602 | |
0c1d7a2c | 5603 | #ifndef CONFIG_PREEMPT_RT |
fbb9ce95 IM |
5604 | /* |
5605 | * We dont accurately track softirq state in e.g. | |
5606 | * hardirq contexts (such as on 4KSTACKS), so only | |
5607 | * check if not in hardirq contexts: | |
5608 | */ | |
5609 | if (!hardirq_count()) { | |
0119fee4 PZ |
5610 | if (softirq_count()) { |
5611 | /* like the above, but with softirqs */ | |
fbb9ce95 | 5612 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
0119fee4 PZ |
5613 | } else { |
5614 | /* lick the above, does it taste good? */ | |
fbb9ce95 | 5615 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
0119fee4 | 5616 | } |
fbb9ce95 | 5617 | } |
0c1d7a2c | 5618 | #endif |
fbb9ce95 IM |
5619 | |
5620 | if (!debug_locks) | |
5621 | print_irqtrace_events(current); | |
77ca93a6 PZ |
5622 | |
5623 | instrumentation_end(); | |
fbb9ce95 IM |
5624 | #endif |
5625 | } | |
5626 | ||
00ef9f73 PZ |
5627 | void lock_set_class(struct lockdep_map *lock, const char *name, |
5628 | struct lock_class_key *key, unsigned int subclass, | |
5629 | unsigned long ip) | |
64aa348e PZ |
5630 | { |
5631 | unsigned long flags; | |
5632 | ||
4d004099 | 5633 | if (unlikely(!lockdep_enabled())) |
64aa348e PZ |
5634 | return; |
5635 | ||
5636 | raw_local_irq_save(flags); | |
4d004099 | 5637 | lockdep_recursion_inc(); |
64aa348e | 5638 | check_flags(flags); |
00ef9f73 | 5639 | if (__lock_set_class(lock, name, key, subclass, ip)) |
64aa348e | 5640 | check_chain_key(current); |
10476e63 | 5641 | lockdep_recursion_finish(); |
64aa348e PZ |
5642 | raw_local_irq_restore(flags); |
5643 | } | |
00ef9f73 | 5644 | EXPORT_SYMBOL_GPL(lock_set_class); |
64aa348e | 5645 | |
6419c4af O |
5646 | void lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
5647 | { | |
5648 | unsigned long flags; | |
5649 | ||
4d004099 | 5650 | if (unlikely(!lockdep_enabled())) |
6419c4af O |
5651 | return; |
5652 | ||
5653 | raw_local_irq_save(flags); | |
4d004099 | 5654 | lockdep_recursion_inc(); |
6419c4af O |
5655 | check_flags(flags); |
5656 | if (__lock_downgrade(lock, ip)) | |
5657 | check_chain_key(current); | |
10476e63 | 5658 | lockdep_recursion_finish(); |
6419c4af O |
5659 | raw_local_irq_restore(flags); |
5660 | } | |
5661 | EXPORT_SYMBOL_GPL(lock_downgrade); | |
5662 | ||
f6f48e18 PZ |
5663 | /* NMI context !!! */ |
5664 | static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass) | |
5665 | { | |
5666 | #ifdef CONFIG_PROVE_LOCKING | |
5667 | struct lock_class *class = look_up_lock_class(lock, subclass); | |
23870f12 | 5668 | unsigned long mask = LOCKF_USED; |
f6f48e18 PZ |
5669 | |
5670 | /* if it doesn't have a class (yet), it certainly hasn't been used yet */ | |
5671 | if (!class) | |
5672 | return; | |
5673 | ||
23870f12 | 5674 | /* |
5675 | * READ locks only conflict with USED, such that if we only ever use | |
5676 | * READ locks, there is no deadlock possible -- RCU. | |
5677 | */ | |
5678 | if (!hlock->read) | |
5679 | mask |= LOCKF_USED_READ; | |
5680 | ||
5681 | if (!(class->usage_mask & mask)) | |
f6f48e18 PZ |
5682 | return; |
5683 | ||
5684 | hlock->class_idx = class - lock_classes; | |
5685 | ||
5686 | print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES); | |
5687 | #endif | |
5688 | } | |
5689 | ||
5690 | static bool lockdep_nmi(void) | |
5691 | { | |
4d004099 | 5692 | if (raw_cpu_read(lockdep_recursion)) |
f6f48e18 PZ |
5693 | return false; |
5694 | ||
5695 | if (!in_nmi()) | |
5696 | return false; | |
5697 | ||
5698 | return true; | |
5699 | } | |
5700 | ||
e9181886 BF |
5701 | /* |
5702 | * read_lock() is recursive if: | |
5703 | * 1. We force lockdep think this way in selftests or | |
5704 | * 2. The implementation is not queued read/write lock or | |
5705 | * 3. The locker is at an in_interrupt() context. | |
5706 | */ | |
5707 | bool read_lock_is_recursive(void) | |
5708 | { | |
5709 | return force_read_lock_recursive || | |
5710 | !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) || | |
5711 | in_interrupt(); | |
5712 | } | |
5713 | EXPORT_SYMBOL_GPL(read_lock_is_recursive); | |
5714 | ||
fbb9ce95 IM |
5715 | /* |
5716 | * We are not always called with irqs disabled - do that here, | |
5717 | * and also avoid lockdep recursion: | |
5718 | */ | |
1d09daa5 | 5719 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
7531e2f3 PZ |
5720 | int trylock, int read, int check, |
5721 | struct lockdep_map *nest_lock, unsigned long ip) | |
fbb9ce95 IM |
5722 | { |
5723 | unsigned long flags; | |
5724 | ||
eb1f0023 PZ |
5725 | trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); |
5726 | ||
4d004099 PZ |
5727 | if (!debug_locks) |
5728 | return; | |
5729 | ||
5730 | if (unlikely(!lockdep_enabled())) { | |
f6f48e18 PZ |
5731 | /* XXX allow trylock from NMI ?!? */ |
5732 | if (lockdep_nmi() && !trylock) { | |
5733 | struct held_lock hlock; | |
5734 | ||
5735 | hlock.acquire_ip = ip; | |
5736 | hlock.instance = lock; | |
5737 | hlock.nest_lock = nest_lock; | |
5738 | hlock.irq_context = 2; // XXX | |
5739 | hlock.trylock = trylock; | |
5740 | hlock.read = read; | |
5741 | hlock.check = check; | |
5742 | hlock.hardirqs_off = true; | |
5743 | hlock.references = 0; | |
5744 | ||
5745 | verify_lock_unused(lock, &hlock, subclass); | |
5746 | } | |
fbb9ce95 | 5747 | return; |
f6f48e18 | 5748 | } |
fbb9ce95 IM |
5749 | |
5750 | raw_local_irq_save(flags); | |
5751 | check_flags(flags); | |
5752 | ||
4d004099 | 5753 | lockdep_recursion_inc(); |
fbb9ce95 | 5754 | __lock_acquire(lock, subclass, trylock, read, check, |
0471db44 | 5755 | irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 0); |
10476e63 | 5756 | lockdep_recursion_finish(); |
fbb9ce95 IM |
5757 | raw_local_irq_restore(flags); |
5758 | } | |
fbb9ce95 IM |
5759 | EXPORT_SYMBOL_GPL(lock_acquire); |
5760 | ||
5facae4f | 5761 | void lock_release(struct lockdep_map *lock, unsigned long ip) |
fbb9ce95 IM |
5762 | { |
5763 | unsigned long flags; | |
5764 | ||
eb1f0023 PZ |
5765 | trace_lock_release(lock, ip); |
5766 | ||
4d004099 | 5767 | if (unlikely(!lockdep_enabled())) |
fbb9ce95 IM |
5768 | return; |
5769 | ||
5770 | raw_local_irq_save(flags); | |
5771 | check_flags(flags); | |
eb1f0023 | 5772 | |
4d004099 | 5773 | lockdep_recursion_inc(); |
b4adfe8e | 5774 | if (__lock_release(lock, ip)) |
e0f56fd7 | 5775 | check_chain_key(current); |
10476e63 | 5776 | lockdep_recursion_finish(); |
fbb9ce95 IM |
5777 | raw_local_irq_restore(flags); |
5778 | } | |
fbb9ce95 IM |
5779 | EXPORT_SYMBOL_GPL(lock_release); |
5780 | ||
2f1f043e BF |
5781 | /* |
5782 | * lock_sync() - A special annotation for synchronize_{s,}rcu()-like API. | |
5783 | * | |
5784 | * No actual critical section is created by the APIs annotated with this: these | |
5785 | * APIs are used to wait for one or multiple critical sections (on other CPUs | |
5786 | * or threads), and it means that calling these APIs inside these critical | |
5787 | * sections is potential deadlock. | |
2f1f043e BF |
5788 | */ |
5789 | void lock_sync(struct lockdep_map *lock, unsigned subclass, int read, | |
5790 | int check, struct lockdep_map *nest_lock, unsigned long ip) | |
5791 | { | |
5792 | unsigned long flags; | |
5793 | ||
5794 | if (unlikely(!lockdep_enabled())) | |
5795 | return; | |
5796 | ||
5797 | raw_local_irq_save(flags); | |
5798 | check_flags(flags); | |
5799 | ||
5800 | lockdep_recursion_inc(); | |
0471db44 BF |
5801 | __lock_acquire(lock, subclass, 0, read, check, |
5802 | irqs_disabled_flags(flags), nest_lock, ip, 0, 0, 1); | |
5803 | check_chain_key(current); | |
2f1f043e BF |
5804 | lockdep_recursion_finish(); |
5805 | raw_local_irq_restore(flags); | |
5806 | } | |
5807 | EXPORT_SYMBOL_GPL(lock_sync); | |
5808 | ||
c86e9b98 | 5809 | noinstr int lock_is_held_type(const struct lockdep_map *lock, int read) |
f607c668 PZ |
5810 | { |
5811 | unsigned long flags; | |
f8cfa466 | 5812 | int ret = LOCK_STATE_NOT_HELD; |
f607c668 | 5813 | |
3e31f947 SK |
5814 | /* |
5815 | * Avoid false negative lockdep_assert_held() and | |
5816 | * lockdep_assert_not_held(). | |
5817 | */ | |
4d004099 | 5818 | if (unlikely(!lockdep_enabled())) |
f8cfa466 | 5819 | return LOCK_STATE_UNKNOWN; |
f607c668 PZ |
5820 | |
5821 | raw_local_irq_save(flags); | |
5822 | check_flags(flags); | |
5823 | ||
4d004099 | 5824 | lockdep_recursion_inc(); |
f8319483 | 5825 | ret = __lock_is_held(lock, read); |
10476e63 | 5826 | lockdep_recursion_finish(); |
f607c668 PZ |
5827 | raw_local_irq_restore(flags); |
5828 | ||
5829 | return ret; | |
5830 | } | |
f8319483 | 5831 | EXPORT_SYMBOL_GPL(lock_is_held_type); |
2f43c602 | 5832 | NOKPROBE_SYMBOL(lock_is_held_type); |
f607c668 | 5833 | |
e7904a28 | 5834 | struct pin_cookie lock_pin_lock(struct lockdep_map *lock) |
a24fc60d | 5835 | { |
e7904a28 | 5836 | struct pin_cookie cookie = NIL_COOKIE; |
a24fc60d PZ |
5837 | unsigned long flags; |
5838 | ||
4d004099 | 5839 | if (unlikely(!lockdep_enabled())) |
e7904a28 | 5840 | return cookie; |
a24fc60d PZ |
5841 | |
5842 | raw_local_irq_save(flags); | |
5843 | check_flags(flags); | |
5844 | ||
4d004099 | 5845 | lockdep_recursion_inc(); |
e7904a28 | 5846 | cookie = __lock_pin_lock(lock); |
10476e63 | 5847 | lockdep_recursion_finish(); |
a24fc60d | 5848 | raw_local_irq_restore(flags); |
e7904a28 PZ |
5849 | |
5850 | return cookie; | |
a24fc60d PZ |
5851 | } |
5852 | EXPORT_SYMBOL_GPL(lock_pin_lock); | |
5853 | ||
e7904a28 PZ |
5854 | void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
5855 | { | |
5856 | unsigned long flags; | |
5857 | ||
4d004099 | 5858 | if (unlikely(!lockdep_enabled())) |
e7904a28 PZ |
5859 | return; |
5860 | ||
5861 | raw_local_irq_save(flags); | |
5862 | check_flags(flags); | |
5863 | ||
4d004099 | 5864 | lockdep_recursion_inc(); |
e7904a28 | 5865 | __lock_repin_lock(lock, cookie); |
10476e63 | 5866 | lockdep_recursion_finish(); |
e7904a28 PZ |
5867 | raw_local_irq_restore(flags); |
5868 | } | |
5869 | EXPORT_SYMBOL_GPL(lock_repin_lock); | |
5870 | ||
5871 | void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) | |
a24fc60d PZ |
5872 | { |
5873 | unsigned long flags; | |
5874 | ||
4d004099 | 5875 | if (unlikely(!lockdep_enabled())) |
a24fc60d PZ |
5876 | return; |
5877 | ||
5878 | raw_local_irq_save(flags); | |
5879 | check_flags(flags); | |
5880 | ||
4d004099 | 5881 | lockdep_recursion_inc(); |
e7904a28 | 5882 | __lock_unpin_lock(lock, cookie); |
10476e63 | 5883 | lockdep_recursion_finish(); |
a24fc60d PZ |
5884 | raw_local_irq_restore(flags); |
5885 | } | |
5886 | EXPORT_SYMBOL_GPL(lock_unpin_lock); | |
5887 | ||
f20786ff | 5888 | #ifdef CONFIG_LOCK_STAT |
f7c1c6b3 YD |
5889 | static void print_lock_contention_bug(struct task_struct *curr, |
5890 | struct lockdep_map *lock, | |
5891 | unsigned long ip) | |
f20786ff PZ |
5892 | { |
5893 | if (!debug_locks_off()) | |
f7c1c6b3 | 5894 | return; |
f20786ff | 5895 | if (debug_locks_silent) |
f7c1c6b3 | 5896 | return; |
f20786ff | 5897 | |
681fbec8 | 5898 | pr_warn("\n"); |
a5dd63ef PM |
5899 | pr_warn("=================================\n"); |
5900 | pr_warn("WARNING: bad contention detected!\n"); | |
fbdc4b9a | 5901 | print_kernel_ident(); |
a5dd63ef | 5902 | pr_warn("---------------------------------\n"); |
681fbec8 | 5903 | pr_warn("%s/%d is trying to contend lock (", |
ba25f9dc | 5904 | curr->comm, task_pid_nr(curr)); |
f20786ff | 5905 | print_lockdep_cache(lock); |
681fbec8 | 5906 | pr_cont(") at:\n"); |
2062a4e8 | 5907 | print_ip_sym(KERN_WARNING, ip); |
681fbec8 PM |
5908 | pr_warn("but there are no locks held!\n"); |
5909 | pr_warn("\nother info that might help us debug this:\n"); | |
f20786ff PZ |
5910 | lockdep_print_held_locks(curr); |
5911 | ||
681fbec8 | 5912 | pr_warn("\nstack backtrace:\n"); |
f20786ff | 5913 | dump_stack(); |
f20786ff PZ |
5914 | } |
5915 | ||
5916 | static void | |
5917 | __lock_contended(struct lockdep_map *lock, unsigned long ip) | |
5918 | { | |
5919 | struct task_struct *curr = current; | |
41c2c5b8 | 5920 | struct held_lock *hlock; |
f20786ff PZ |
5921 | struct lock_class_stats *stats; |
5922 | unsigned int depth; | |
c7e78cff | 5923 | int i, contention_point, contending_point; |
f20786ff PZ |
5924 | |
5925 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
5926 | /* |
5927 | * Whee, we contended on this lock, except it seems we're not | |
5928 | * actually trying to acquire anything much at all.. | |
5929 | */ | |
f20786ff PZ |
5930 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5931 | return; | |
5932 | ||
41c2c5b8 O |
5933 | hlock = find_held_lock(curr, lock, depth, &i); |
5934 | if (!hlock) { | |
5935 | print_lock_contention_bug(curr, lock, ip); | |
5936 | return; | |
f20786ff | 5937 | } |
f20786ff | 5938 | |
bb97a91e PZ |
5939 | if (hlock->instance != lock) |
5940 | return; | |
5941 | ||
3365e779 | 5942 | hlock->waittime_stamp = lockstat_clock(); |
f20786ff | 5943 | |
c7e78cff PZ |
5944 | contention_point = lock_point(hlock_class(hlock)->contention_point, ip); |
5945 | contending_point = lock_point(hlock_class(hlock)->contending_point, | |
5946 | lock->ip); | |
f20786ff | 5947 | |
f82b217e | 5948 | stats = get_lock_stats(hlock_class(hlock)); |
c7e78cff PZ |
5949 | if (contention_point < LOCKSTAT_POINTS) |
5950 | stats->contention_point[contention_point]++; | |
5951 | if (contending_point < LOCKSTAT_POINTS) | |
5952 | stats->contending_point[contending_point]++; | |
96645678 PZ |
5953 | if (lock->cpu != smp_processor_id()) |
5954 | stats->bounces[bounce_contended + !!hlock->read]++; | |
f20786ff PZ |
5955 | } |
5956 | ||
5957 | static void | |
c7e78cff | 5958 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
f20786ff PZ |
5959 | { |
5960 | struct task_struct *curr = current; | |
41c2c5b8 | 5961 | struct held_lock *hlock; |
f20786ff PZ |
5962 | struct lock_class_stats *stats; |
5963 | unsigned int depth; | |
3365e779 | 5964 | u64 now, waittime = 0; |
96645678 | 5965 | int i, cpu; |
f20786ff PZ |
5966 | |
5967 | depth = curr->lockdep_depth; | |
0119fee4 PZ |
5968 | /* |
5969 | * Yay, we acquired ownership of this lock we didn't try to | |
5970 | * acquire, how the heck did that happen? | |
5971 | */ | |
f20786ff PZ |
5972 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5973 | return; | |
5974 | ||
41c2c5b8 O |
5975 | hlock = find_held_lock(curr, lock, depth, &i); |
5976 | if (!hlock) { | |
5977 | print_lock_contention_bug(curr, lock, _RET_IP_); | |
5978 | return; | |
f20786ff | 5979 | } |
f20786ff | 5980 | |
bb97a91e PZ |
5981 | if (hlock->instance != lock) |
5982 | return; | |
5983 | ||
96645678 PZ |
5984 | cpu = smp_processor_id(); |
5985 | if (hlock->waittime_stamp) { | |
3365e779 | 5986 | now = lockstat_clock(); |
96645678 PZ |
5987 | waittime = now - hlock->waittime_stamp; |
5988 | hlock->holdtime_stamp = now; | |
5989 | } | |
f20786ff | 5990 | |
f82b217e | 5991 | stats = get_lock_stats(hlock_class(hlock)); |
96645678 PZ |
5992 | if (waittime) { |
5993 | if (hlock->read) | |
5994 | lock_time_inc(&stats->read_waittime, waittime); | |
5995 | else | |
5996 | lock_time_inc(&stats->write_waittime, waittime); | |
5997 | } | |
5998 | if (lock->cpu != cpu) | |
5999 | stats->bounces[bounce_acquired + !!hlock->read]++; | |
96645678 PZ |
6000 | |
6001 | lock->cpu = cpu; | |
c7e78cff | 6002 | lock->ip = ip; |
f20786ff PZ |
6003 | } |
6004 | ||
6005 | void lock_contended(struct lockdep_map *lock, unsigned long ip) | |
6006 | { | |
6007 | unsigned long flags; | |
6008 | ||
89e70d5c | 6009 | trace_lock_contended(lock, ip); |
eb1f0023 | 6010 | |
4d004099 | 6011 | if (unlikely(!lock_stat || !lockdep_enabled())) |
f20786ff PZ |
6012 | return; |
6013 | ||
6014 | raw_local_irq_save(flags); | |
6015 | check_flags(flags); | |
4d004099 | 6016 | lockdep_recursion_inc(); |
f20786ff | 6017 | __lock_contended(lock, ip); |
10476e63 | 6018 | lockdep_recursion_finish(); |
f20786ff PZ |
6019 | raw_local_irq_restore(flags); |
6020 | } | |
6021 | EXPORT_SYMBOL_GPL(lock_contended); | |
6022 | ||
c7e78cff | 6023 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
f20786ff PZ |
6024 | { |
6025 | unsigned long flags; | |
6026 | ||
89e70d5c | 6027 | trace_lock_acquired(lock, ip); |
eb1f0023 | 6028 | |
4d004099 | 6029 | if (unlikely(!lock_stat || !lockdep_enabled())) |
f20786ff PZ |
6030 | return; |
6031 | ||
6032 | raw_local_irq_save(flags); | |
6033 | check_flags(flags); | |
4d004099 | 6034 | lockdep_recursion_inc(); |
c7e78cff | 6035 | __lock_acquired(lock, ip); |
10476e63 | 6036 | lockdep_recursion_finish(); |
f20786ff PZ |
6037 | raw_local_irq_restore(flags); |
6038 | } | |
6039 | EXPORT_SYMBOL_GPL(lock_acquired); | |
6040 | #endif | |
6041 | ||
fbb9ce95 IM |
6042 | /* |
6043 | * Used by the testsuite, sanitize the validator state | |
6044 | * after a simulated failure: | |
6045 | */ | |
6046 | ||
6047 | void lockdep_reset(void) | |
6048 | { | |
6049 | unsigned long flags; | |
23d95a03 | 6050 | int i; |
fbb9ce95 IM |
6051 | |
6052 | raw_local_irq_save(flags); | |
e196e479 | 6053 | lockdep_init_task(current); |
fbb9ce95 IM |
6054 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
6055 | nr_hardirq_chains = 0; | |
6056 | nr_softirq_chains = 0; | |
6057 | nr_process_chains = 0; | |
6058 | debug_locks = 1; | |
23d95a03 | 6059 | for (i = 0; i < CHAINHASH_SIZE; i++) |
a63f38cc | 6060 | INIT_HLIST_HEAD(chainhash_table + i); |
fbb9ce95 IM |
6061 | raw_local_irq_restore(flags); |
6062 | } | |
6063 | ||
a0b0fd53 | 6064 | /* Remove a class from a lock chain. Must be called with the graph lock held. */ |
de4643a7 BVA |
6065 | static void remove_class_from_lock_chain(struct pending_free *pf, |
6066 | struct lock_chain *chain, | |
a0b0fd53 BVA |
6067 | struct lock_class *class) |
6068 | { | |
6069 | #ifdef CONFIG_PROVE_LOCKING | |
a0b0fd53 BVA |
6070 | int i; |
6071 | ||
6072 | for (i = chain->base; i < chain->base + chain->depth; i++) { | |
f611e8cf | 6073 | if (chain_hlock_class_idx(chain_hlocks[i]) != class - lock_classes) |
a0b0fd53 | 6074 | continue; |
a0b0fd53 BVA |
6075 | /* |
6076 | * Each lock class occurs at most once in a lock chain so once | |
6077 | * we found a match we can break out of this loop. | |
6078 | */ | |
836bd74b | 6079 | goto free_lock_chain; |
a0b0fd53 BVA |
6080 | } |
6081 | /* Since the chain has not been modified, return. */ | |
6082 | return; | |
6083 | ||
836bd74b | 6084 | free_lock_chain: |
810507fe | 6085 | free_chain_hlocks(chain->base, chain->depth); |
a0b0fd53 | 6086 | /* Overwrite the chain key for concurrent RCU readers. */ |
836bd74b | 6087 | WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); |
b3b9c187 WL |
6088 | dec_chains(chain->irq_context); |
6089 | ||
a0b0fd53 BVA |
6090 | /* |
6091 | * Note: calling hlist_del_rcu() from inside a | |
6092 | * hlist_for_each_entry_rcu() loop is safe. | |
6093 | */ | |
6094 | hlist_del_rcu(&chain->entry); | |
de4643a7 | 6095 | __set_bit(chain - lock_chains, pf->lock_chains_being_freed); |
797b82eb | 6096 | nr_zapped_lock_chains++; |
a0b0fd53 BVA |
6097 | #endif |
6098 | } | |
6099 | ||
6100 | /* Must be called with the graph lock held. */ | |
de4643a7 BVA |
6101 | static void remove_class_from_lock_chains(struct pending_free *pf, |
6102 | struct lock_class *class) | |
a0b0fd53 BVA |
6103 | { |
6104 | struct lock_chain *chain; | |
6105 | struct hlist_head *head; | |
6106 | int i; | |
6107 | ||
6108 | for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { | |
6109 | head = chainhash_table + i; | |
6110 | hlist_for_each_entry_rcu(chain, head, entry) { | |
de4643a7 | 6111 | remove_class_from_lock_chain(pf, chain, class); |
a0b0fd53 BVA |
6112 | } |
6113 | } | |
6114 | } | |
6115 | ||
786fa29e BVA |
6116 | /* |
6117 | * Remove all references to a lock class. The caller must hold the graph lock. | |
6118 | */ | |
a0b0fd53 | 6119 | static void zap_class(struct pending_free *pf, struct lock_class *class) |
fbb9ce95 | 6120 | { |
86cffb80 | 6121 | struct lock_list *entry; |
fbb9ce95 IM |
6122 | int i; |
6123 | ||
a0b0fd53 BVA |
6124 | WARN_ON_ONCE(!class->key); |
6125 | ||
fbb9ce95 IM |
6126 | /* |
6127 | * Remove all dependencies this lock is | |
6128 | * involved in: | |
6129 | */ | |
ace35a7a BVA |
6130 | for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { |
6131 | entry = list_entries + i; | |
86cffb80 BVA |
6132 | if (entry->class != class && entry->links_to != class) |
6133 | continue; | |
ace35a7a BVA |
6134 | __clear_bit(i, list_entries_in_use); |
6135 | nr_list_entries--; | |
86cffb80 | 6136 | list_del_rcu(&entry->entry); |
fbb9ce95 | 6137 | } |
a0b0fd53 BVA |
6138 | if (list_empty(&class->locks_after) && |
6139 | list_empty(&class->locks_before)) { | |
6140 | list_move_tail(&class->lock_entry, &pf->zapped); | |
6141 | hlist_del_rcu(&class->hash_entry); | |
6142 | WRITE_ONCE(class->key, NULL); | |
6143 | WRITE_ONCE(class->name, NULL); | |
6144 | nr_lock_classes--; | |
01bb6f0a | 6145 | __clear_bit(class - lock_classes, lock_classes_in_use); |
fb7275ac WL |
6146 | if (class - lock_classes == max_lock_class_idx) |
6147 | max_lock_class_idx--; | |
a0b0fd53 BVA |
6148 | } else { |
6149 | WARN_ONCE(true, "%s() failed for class %s\n", __func__, | |
6150 | class->name); | |
6151 | } | |
fbb9ce95 | 6152 | |
de4643a7 | 6153 | remove_class_from_lock_chains(pf, class); |
1d44bcb4 | 6154 | nr_zapped_classes++; |
a0b0fd53 BVA |
6155 | } |
6156 | ||
6157 | static void reinit_class(struct lock_class *class) | |
6158 | { | |
a0b0fd53 BVA |
6159 | WARN_ON_ONCE(!class->lock_entry.next); |
6160 | WARN_ON_ONCE(!list_empty(&class->locks_after)); | |
6161 | WARN_ON_ONCE(!list_empty(&class->locks_before)); | |
e204193b | 6162 | memset_startat(class, 0, key); |
a0b0fd53 BVA |
6163 | WARN_ON_ONCE(!class->lock_entry.next); |
6164 | WARN_ON_ONCE(!list_empty(&class->locks_after)); | |
6165 | WARN_ON_ONCE(!list_empty(&class->locks_before)); | |
fbb9ce95 IM |
6166 | } |
6167 | ||
fabe874a | 6168 | static inline int within(const void *addr, void *start, unsigned long size) |
fbb9ce95 IM |
6169 | { |
6170 | return addr >= start && addr < start + size; | |
6171 | } | |
6172 | ||
a0b0fd53 BVA |
6173 | static bool inside_selftest(void) |
6174 | { | |
6175 | return current == lockdep_selftest_task_struct; | |
6176 | } | |
6177 | ||
6178 | /* The caller must hold the graph lock. */ | |
6179 | static struct pending_free *get_pending_free(void) | |
6180 | { | |
6181 | return delayed_free.pf + delayed_free.index; | |
6182 | } | |
6183 | ||
6184 | static void free_zapped_rcu(struct rcu_head *cb); | |
6185 | ||
6186 | /* | |
6187 | * Schedule an RCU callback if no RCU callback is pending. Must be called with | |
6188 | * the graph lock held. | |
6189 | */ | |
6190 | static void call_rcu_zapped(struct pending_free *pf) | |
6191 | { | |
6192 | WARN_ON_ONCE(inside_selftest()); | |
6193 | ||
6194 | if (list_empty(&pf->zapped)) | |
6195 | return; | |
6196 | ||
6197 | if (delayed_free.scheduled) | |
6198 | return; | |
6199 | ||
6200 | delayed_free.scheduled = true; | |
6201 | ||
6202 | WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf); | |
6203 | delayed_free.index ^= 1; | |
6204 | ||
6205 | call_rcu(&delayed_free.rcu_head, free_zapped_rcu); | |
6206 | } | |
6207 | ||
6208 | /* The caller must hold the graph lock. May be called from RCU context. */ | |
6209 | static void __free_zapped_classes(struct pending_free *pf) | |
6210 | { | |
6211 | struct lock_class *class; | |
6212 | ||
72dcd505 | 6213 | check_data_structures(); |
b526b2e3 | 6214 | |
a0b0fd53 BVA |
6215 | list_for_each_entry(class, &pf->zapped, lock_entry) |
6216 | reinit_class(class); | |
6217 | ||
6218 | list_splice_init(&pf->zapped, &free_lock_classes); | |
de4643a7 BVA |
6219 | |
6220 | #ifdef CONFIG_PROVE_LOCKING | |
6221 | bitmap_andnot(lock_chains_in_use, lock_chains_in_use, | |
6222 | pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains)); | |
6223 | bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains)); | |
6224 | #endif | |
a0b0fd53 BVA |
6225 | } |
6226 | ||
6227 | static void free_zapped_rcu(struct rcu_head *ch) | |
6228 | { | |
6229 | struct pending_free *pf; | |
6230 | unsigned long flags; | |
6231 | ||
6232 | if (WARN_ON_ONCE(ch != &delayed_free.rcu_head)) | |
6233 | return; | |
6234 | ||
6235 | raw_local_irq_save(flags); | |
248efb21 | 6236 | lockdep_lock(); |
a0b0fd53 BVA |
6237 | |
6238 | /* closed head */ | |
6239 | pf = delayed_free.pf + (delayed_free.index ^ 1); | |
6240 | __free_zapped_classes(pf); | |
6241 | delayed_free.scheduled = false; | |
6242 | ||
6243 | /* | |
6244 | * If there's anything on the open list, close and start a new callback. | |
6245 | */ | |
6246 | call_rcu_zapped(delayed_free.pf + delayed_free.index); | |
6247 | ||
248efb21 | 6248 | lockdep_unlock(); |
a0b0fd53 BVA |
6249 | raw_local_irq_restore(flags); |
6250 | } | |
6251 | ||
6252 | /* | |
6253 | * Remove all lock classes from the class hash table and from the | |
6254 | * all_lock_classes list whose key or name is in the address range [start, | |
6255 | * start + size). Move these lock classes to the zapped_classes list. Must | |
6256 | * be called with the graph lock held. | |
6257 | */ | |
6258 | static void __lockdep_free_key_range(struct pending_free *pf, void *start, | |
6259 | unsigned long size) | |
956f3563 BVA |
6260 | { |
6261 | struct lock_class *class; | |
6262 | struct hlist_head *head; | |
6263 | int i; | |
6264 | ||
6265 | /* Unhash all classes that were created by a module. */ | |
6266 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
6267 | head = classhash_table + i; | |
6268 | hlist_for_each_entry_rcu(class, head, hash_entry) { | |
6269 | if (!within(class->key, start, size) && | |
6270 | !within(class->name, start, size)) | |
6271 | continue; | |
a0b0fd53 | 6272 | zap_class(pf, class); |
956f3563 BVA |
6273 | } |
6274 | } | |
6275 | } | |
6276 | ||
35a9393c PZ |
6277 | /* |
6278 | * Used in module.c to remove lock classes from memory that is going to be | |
6279 | * freed; and possibly re-used by other modules. | |
6280 | * | |
29fc33fb BVA |
6281 | * We will have had one synchronize_rcu() before getting here, so we're |
6282 | * guaranteed nobody will look up these exact classes -- they're properly dead | |
6283 | * but still allocated. | |
35a9393c | 6284 | */ |
a0b0fd53 | 6285 | static void lockdep_free_key_range_reg(void *start, unsigned long size) |
fbb9ce95 | 6286 | { |
a0b0fd53 | 6287 | struct pending_free *pf; |
fbb9ce95 | 6288 | unsigned long flags; |
fbb9ce95 | 6289 | |
feb0a386 BVA |
6290 | init_data_structures_once(); |
6291 | ||
fbb9ce95 | 6292 | raw_local_irq_save(flags); |
248efb21 | 6293 | lockdep_lock(); |
a0b0fd53 BVA |
6294 | pf = get_pending_free(); |
6295 | __lockdep_free_key_range(pf, start, size); | |
6296 | call_rcu_zapped(pf); | |
248efb21 | 6297 | lockdep_unlock(); |
fbb9ce95 | 6298 | raw_local_irq_restore(flags); |
35a9393c PZ |
6299 | |
6300 | /* | |
6301 | * Wait for any possible iterators from look_up_lock_class() to pass | |
6302 | * before continuing to free the memory they refer to. | |
35a9393c | 6303 | */ |
51959d85 | 6304 | synchronize_rcu(); |
a0b0fd53 | 6305 | } |
35a9393c | 6306 | |
a0b0fd53 BVA |
6307 | /* |
6308 | * Free all lockdep keys in the range [start, start+size). Does not sleep. | |
6309 | * Ignores debug_locks. Must only be used by the lockdep selftests. | |
6310 | */ | |
6311 | static void lockdep_free_key_range_imm(void *start, unsigned long size) | |
6312 | { | |
6313 | struct pending_free *pf = delayed_free.pf; | |
6314 | unsigned long flags; | |
6315 | ||
6316 | init_data_structures_once(); | |
6317 | ||
6318 | raw_local_irq_save(flags); | |
248efb21 | 6319 | lockdep_lock(); |
a0b0fd53 BVA |
6320 | __lockdep_free_key_range(pf, start, size); |
6321 | __free_zapped_classes(pf); | |
248efb21 | 6322 | lockdep_unlock(); |
a0b0fd53 BVA |
6323 | raw_local_irq_restore(flags); |
6324 | } | |
6325 | ||
6326 | void lockdep_free_key_range(void *start, unsigned long size) | |
6327 | { | |
6328 | init_data_structures_once(); | |
6329 | ||
6330 | if (inside_selftest()) | |
6331 | lockdep_free_key_range_imm(start, size); | |
6332 | else | |
6333 | lockdep_free_key_range_reg(start, size); | |
fbb9ce95 IM |
6334 | } |
6335 | ||
2904d9fa BVA |
6336 | /* |
6337 | * Check whether any element of the @lock->class_cache[] array refers to a | |
6338 | * registered lock class. The caller must hold either the graph lock or the | |
6339 | * RCU read lock. | |
6340 | */ | |
6341 | static bool lock_class_cache_is_registered(struct lockdep_map *lock) | |
fbb9ce95 | 6342 | { |
35a9393c | 6343 | struct lock_class *class; |
a63f38cc | 6344 | struct hlist_head *head; |
fbb9ce95 | 6345 | int i, j; |
2904d9fa BVA |
6346 | |
6347 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
6348 | head = classhash_table + i; | |
6349 | hlist_for_each_entry_rcu(class, head, hash_entry) { | |
6350 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) | |
6351 | if (lock->class_cache[j] == class) | |
6352 | return true; | |
6353 | } | |
6354 | } | |
6355 | return false; | |
6356 | } | |
6357 | ||
956f3563 | 6358 | /* The caller must hold the graph lock. Does not sleep. */ |
a0b0fd53 BVA |
6359 | static void __lockdep_reset_lock(struct pending_free *pf, |
6360 | struct lockdep_map *lock) | |
2904d9fa BVA |
6361 | { |
6362 | struct lock_class *class; | |
956f3563 | 6363 | int j; |
fbb9ce95 IM |
6364 | |
6365 | /* | |
d6d897ce IM |
6366 | * Remove all classes this lock might have: |
6367 | */ | |
6368 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
6369 | /* | |
6370 | * If the class exists we look it up and zap it: | |
6371 | */ | |
6372 | class = look_up_lock_class(lock, j); | |
64f29d1b | 6373 | if (class) |
a0b0fd53 | 6374 | zap_class(pf, class); |
d6d897ce IM |
6375 | } |
6376 | /* | |
6377 | * Debug check: in the end all mapped classes should | |
6378 | * be gone. | |
fbb9ce95 | 6379 | */ |
956f3563 BVA |
6380 | if (WARN_ON_ONCE(lock_class_cache_is_registered(lock))) |
6381 | debug_locks_off(); | |
6382 | } | |
6383 | ||
a0b0fd53 BVA |
6384 | /* |
6385 | * Remove all information lockdep has about a lock if debug_locks == 1. Free | |
6386 | * released data structures from RCU context. | |
6387 | */ | |
6388 | static void lockdep_reset_lock_reg(struct lockdep_map *lock) | |
956f3563 | 6389 | { |
a0b0fd53 | 6390 | struct pending_free *pf; |
956f3563 BVA |
6391 | unsigned long flags; |
6392 | int locked; | |
6393 | ||
956f3563 BVA |
6394 | raw_local_irq_save(flags); |
6395 | locked = graph_lock(); | |
a0b0fd53 BVA |
6396 | if (!locked) |
6397 | goto out_irq; | |
6398 | ||
6399 | pf = get_pending_free(); | |
6400 | __lockdep_reset_lock(pf, lock); | |
6401 | call_rcu_zapped(pf); | |
6402 | ||
6403 | graph_unlock(); | |
6404 | out_irq: | |
6405 | raw_local_irq_restore(flags); | |
6406 | } | |
6407 | ||
6408 | /* | |
6409 | * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the | |
6410 | * lockdep selftests. | |
6411 | */ | |
6412 | static void lockdep_reset_lock_imm(struct lockdep_map *lock) | |
6413 | { | |
6414 | struct pending_free *pf = delayed_free.pf; | |
6415 | unsigned long flags; | |
6416 | ||
6417 | raw_local_irq_save(flags); | |
248efb21 | 6418 | lockdep_lock(); |
a0b0fd53 BVA |
6419 | __lockdep_reset_lock(pf, lock); |
6420 | __free_zapped_classes(pf); | |
248efb21 | 6421 | lockdep_unlock(); |
fbb9ce95 IM |
6422 | raw_local_irq_restore(flags); |
6423 | } | |
6424 | ||
a0b0fd53 BVA |
6425 | void lockdep_reset_lock(struct lockdep_map *lock) |
6426 | { | |
6427 | init_data_structures_once(); | |
6428 | ||
6429 | if (inside_selftest()) | |
6430 | lockdep_reset_lock_imm(lock); | |
6431 | else | |
6432 | lockdep_reset_lock_reg(lock); | |
6433 | } | |
6434 | ||
61cc4534 WL |
6435 | /* |
6436 | * Unregister a dynamically allocated key. | |
6437 | * | |
6438 | * Unlike lockdep_register_key(), a search is always done to find a matching | |
6439 | * key irrespective of debug_locks to avoid potential invalid access to freed | |
6440 | * memory in lock_class entry. | |
6441 | */ | |
108c1485 BVA |
6442 | void lockdep_unregister_key(struct lock_class_key *key) |
6443 | { | |
6444 | struct hlist_head *hash_head = keyhashentry(key); | |
6445 | struct lock_class_key *k; | |
6446 | struct pending_free *pf; | |
6447 | unsigned long flags; | |
6448 | bool found = false; | |
6449 | ||
6450 | might_sleep(); | |
6451 | ||
6452 | if (WARN_ON_ONCE(static_obj(key))) | |
6453 | return; | |
6454 | ||
6455 | raw_local_irq_save(flags); | |
61cc4534 | 6456 | lockdep_lock(); |
8b39adbe | 6457 | |
108c1485 BVA |
6458 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { |
6459 | if (k == key) { | |
6460 | hlist_del_rcu(&k->hash_entry); | |
6461 | found = true; | |
6462 | break; | |
6463 | } | |
6464 | } | |
61cc4534 WL |
6465 | WARN_ON_ONCE(!found && debug_locks); |
6466 | if (found) { | |
6467 | pf = get_pending_free(); | |
6468 | __lockdep_free_key_range(pf, key, 1); | |
6469 | call_rcu_zapped(pf); | |
6470 | } | |
6471 | lockdep_unlock(); | |
108c1485 BVA |
6472 | raw_local_irq_restore(flags); |
6473 | ||
6474 | /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */ | |
6475 | synchronize_rcu(); | |
6476 | } | |
6477 | EXPORT_SYMBOL_GPL(lockdep_unregister_key); | |
6478 | ||
c3bc8fd6 | 6479 | void __init lockdep_init(void) |
fbb9ce95 IM |
6480 | { |
6481 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
6482 | ||
b0788caf | 6483 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); |
fbb9ce95 IM |
6484 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); |
6485 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
b0788caf | 6486 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); |
fbb9ce95 IM |
6487 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); |
6488 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
6489 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
6490 | ||
09d75ecb | 6491 | printk(" memory used by lock dependency info: %zu kB\n", |
7ff8517e | 6492 | (sizeof(lock_classes) + |
01bb6f0a | 6493 | sizeof(lock_classes_in_use) + |
7ff8517e BVA |
6494 | sizeof(classhash_table) + |
6495 | sizeof(list_entries) + | |
ace35a7a | 6496 | sizeof(list_entries_in_use) + |
a0b0fd53 BVA |
6497 | sizeof(chainhash_table) + |
6498 | sizeof(delayed_free) | |
4dd861d6 | 6499 | #ifdef CONFIG_PROVE_LOCKING |
7ff8517e | 6500 | + sizeof(lock_cq) |
15ea86b5 | 6501 | + sizeof(lock_chains) |
de4643a7 | 6502 | + sizeof(lock_chains_in_use) |
15ea86b5 | 6503 | + sizeof(chain_hlocks) |
4dd861d6 | 6504 | #endif |
90629209 | 6505 | ) / 1024 |
4dd861d6 | 6506 | ); |
fbb9ce95 | 6507 | |
12593b74 BVA |
6508 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
6509 | printk(" memory used for stack traces: %zu kB\n", | |
6510 | (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024 | |
6511 | ); | |
6512 | #endif | |
6513 | ||
09d75ecb | 6514 | printk(" per task-struct memory footprint: %zu bytes\n", |
7ff8517e | 6515 | sizeof(((struct task_struct *)NULL)->held_locks)); |
fbb9ce95 IM |
6516 | } |
6517 | ||
fbb9ce95 IM |
6518 | static void |
6519 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
55794a41 | 6520 | const void *mem_to, struct held_lock *hlock) |
fbb9ce95 IM |
6521 | { |
6522 | if (!debug_locks_off()) | |
6523 | return; | |
6524 | if (debug_locks_silent) | |
6525 | return; | |
6526 | ||
681fbec8 | 6527 | pr_warn("\n"); |
a5dd63ef PM |
6528 | pr_warn("=========================\n"); |
6529 | pr_warn("WARNING: held lock freed!\n"); | |
fbdc4b9a | 6530 | print_kernel_ident(); |
a5dd63ef | 6531 | pr_warn("-------------------------\n"); |
04860d48 | 6532 | pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n", |
ba25f9dc | 6533 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
55794a41 | 6534 | print_lock(hlock); |
fbb9ce95 IM |
6535 | lockdep_print_held_locks(curr); |
6536 | ||
681fbec8 | 6537 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
6538 | dump_stack(); |
6539 | } | |
6540 | ||
54561783 ON |
6541 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
6542 | const void* lock_from, unsigned long lock_len) | |
6543 | { | |
6544 | return lock_from + lock_len <= mem_from || | |
6545 | mem_from + mem_len <= lock_from; | |
6546 | } | |
6547 | ||
fbb9ce95 IM |
6548 | /* |
6549 | * Called when kernel memory is freed (or unmapped), or if a lock | |
6550 | * is destroyed or reinitialized - this code checks whether there is | |
6551 | * any held lock in the memory range of <from> to <to>: | |
6552 | */ | |
6553 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
6554 | { | |
fbb9ce95 IM |
6555 | struct task_struct *curr = current; |
6556 | struct held_lock *hlock; | |
6557 | unsigned long flags; | |
6558 | int i; | |
6559 | ||
6560 | if (unlikely(!debug_locks)) | |
6561 | return; | |
6562 | ||
fcc784be | 6563 | raw_local_irq_save(flags); |
fbb9ce95 IM |
6564 | for (i = 0; i < curr->lockdep_depth; i++) { |
6565 | hlock = curr->held_locks + i; | |
6566 | ||
54561783 ON |
6567 | if (not_in_range(mem_from, mem_len, hlock->instance, |
6568 | sizeof(*hlock->instance))) | |
fbb9ce95 IM |
6569 | continue; |
6570 | ||
54561783 | 6571 | print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); |
fbb9ce95 IM |
6572 | break; |
6573 | } | |
fcc784be | 6574 | raw_local_irq_restore(flags); |
fbb9ce95 | 6575 | } |
ed07536e | 6576 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
fbb9ce95 | 6577 | |
1b1d2fb4 | 6578 | static void print_held_locks_bug(void) |
fbb9ce95 IM |
6579 | { |
6580 | if (!debug_locks_off()) | |
6581 | return; | |
6582 | if (debug_locks_silent) | |
6583 | return; | |
6584 | ||
681fbec8 | 6585 | pr_warn("\n"); |
a5dd63ef PM |
6586 | pr_warn("====================================\n"); |
6587 | pr_warn("WARNING: %s/%d still has locks held!\n", | |
1b1d2fb4 | 6588 | current->comm, task_pid_nr(current)); |
fbdc4b9a | 6589 | print_kernel_ident(); |
a5dd63ef | 6590 | pr_warn("------------------------------------\n"); |
1b1d2fb4 | 6591 | lockdep_print_held_locks(current); |
681fbec8 | 6592 | pr_warn("\nstack backtrace:\n"); |
fbb9ce95 IM |
6593 | dump_stack(); |
6594 | } | |
6595 | ||
1b1d2fb4 | 6596 | void debug_check_no_locks_held(void) |
fbb9ce95 | 6597 | { |
1b1d2fb4 CC |
6598 | if (unlikely(current->lockdep_depth > 0)) |
6599 | print_held_locks_bug(); | |
fbb9ce95 | 6600 | } |
1b1d2fb4 | 6601 | EXPORT_SYMBOL_GPL(debug_check_no_locks_held); |
fbb9ce95 | 6602 | |
8dce7a9a | 6603 | #ifdef __KERNEL__ |
fbb9ce95 IM |
6604 | void debug_show_all_locks(void) |
6605 | { | |
6606 | struct task_struct *g, *p; | |
fbb9ce95 | 6607 | |
9c35dd7f | 6608 | if (unlikely(!debug_locks)) { |
681fbec8 | 6609 | pr_warn("INFO: lockdep is turned off.\n"); |
9c35dd7f JP |
6610 | return; |
6611 | } | |
681fbec8 | 6612 | pr_warn("\nShowing all locks held in the system:\n"); |
fbb9ce95 | 6613 | |
0f736a52 TH |
6614 | rcu_read_lock(); |
6615 | for_each_process_thread(g, p) { | |
0f736a52 TH |
6616 | if (!p->lockdep_depth) |
6617 | continue; | |
6618 | lockdep_print_held_locks(p); | |
88f1c87d | 6619 | touch_nmi_watchdog(); |
0f736a52 TH |
6620 | touch_all_softlockup_watchdogs(); |
6621 | } | |
6622 | rcu_read_unlock(); | |
fbb9ce95 | 6623 | |
681fbec8 | 6624 | pr_warn("\n"); |
a5dd63ef | 6625 | pr_warn("=============================================\n\n"); |
fbb9ce95 | 6626 | } |
fbb9ce95 | 6627 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
8dce7a9a | 6628 | #endif |
fbb9ce95 | 6629 | |
82a1fcb9 IM |
6630 | /* |
6631 | * Careful: only use this function if you are sure that | |
6632 | * the task cannot run in parallel! | |
6633 | */ | |
f1b499f0 | 6634 | void debug_show_held_locks(struct task_struct *task) |
fbb9ce95 | 6635 | { |
9c35dd7f JP |
6636 | if (unlikely(!debug_locks)) { |
6637 | printk("INFO: lockdep is turned off.\n"); | |
6638 | return; | |
6639 | } | |
fbb9ce95 IM |
6640 | lockdep_print_held_locks(task); |
6641 | } | |
fbb9ce95 | 6642 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
b351d164 | 6643 | |
722a9f92 | 6644 | asmlinkage __visible void lockdep_sys_exit(void) |
b351d164 PZ |
6645 | { |
6646 | struct task_struct *curr = current; | |
6647 | ||
6648 | if (unlikely(curr->lockdep_depth)) { | |
6649 | if (!debug_locks_off()) | |
6650 | return; | |
681fbec8 | 6651 | pr_warn("\n"); |
a5dd63ef PM |
6652 | pr_warn("================================================\n"); |
6653 | pr_warn("WARNING: lock held when returning to user space!\n"); | |
fbdc4b9a | 6654 | print_kernel_ident(); |
a5dd63ef | 6655 | pr_warn("------------------------------------------------\n"); |
681fbec8 | 6656 | pr_warn("%s/%d is leaving the kernel with locks still held!\n", |
b351d164 PZ |
6657 | curr->comm, curr->pid); |
6658 | lockdep_print_held_locks(curr); | |
6659 | } | |
b09be676 BP |
6660 | |
6661 | /* | |
6662 | * The lock history for each syscall should be independent. So wipe the | |
6663 | * slate clean on return to userspace. | |
6664 | */ | |
f52be570 | 6665 | lockdep_invariant_state(false); |
b351d164 | 6666 | } |
0632eb3d | 6667 | |
b3fbab05 | 6668 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) |
0632eb3d PM |
6669 | { |
6670 | struct task_struct *curr = current; | |
1feb2cc8 | 6671 | int dl = READ_ONCE(debug_locks); |
5a5d7e9b | 6672 | bool rcu = warn_rcu_enter(); |
0632eb3d | 6673 | |
2b3fc35f | 6674 | /* Note: the following can be executed concurrently, so be careful. */ |
681fbec8 | 6675 | pr_warn("\n"); |
a5dd63ef PM |
6676 | pr_warn("=============================\n"); |
6677 | pr_warn("WARNING: suspicious RCU usage\n"); | |
fbdc4b9a | 6678 | print_kernel_ident(); |
a5dd63ef | 6679 | pr_warn("-----------------------------\n"); |
681fbec8 PM |
6680 | pr_warn("%s:%d %s!\n", file, line, s); |
6681 | pr_warn("\nother info that might help us debug this:\n\n"); | |
1feb2cc8 | 6682 | pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s", |
c5fdcec9 PM |
6683 | !rcu_lockdep_current_cpu_online() |
6684 | ? "RCU used illegally from offline CPU!\n" | |
d29e0b26 | 6685 | : "", |
1feb2cc8 PM |
6686 | rcu_scheduler_active, dl, |
6687 | dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n"); | |
0464e937 FW |
6688 | |
6689 | /* | |
6690 | * If a CPU is in the RCU-free window in idle (ie: in the section | |
e67198cc | 6691 | * between ct_idle_enter() and ct_idle_exit(), then RCU |
0464e937 FW |
6692 | * considers that CPU to be in an "extended quiescent state", |
6693 | * which means that RCU will be completely ignoring that CPU. | |
6694 | * Therefore, rcu_read_lock() and friends have absolutely no | |
6695 | * effect on a CPU running in that state. In other words, even if | |
6696 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well | |
6697 | * delete data structures out from under it. RCU really has no | |
6698 | * choice here: we need to keep an RCU-free window in idle where | |
6699 | * the CPU may possibly enter into low power mode. This way we can | |
6700 | * notice an extended quiescent state to other CPUs that started a grace | |
6701 | * period. Otherwise we would delay any grace period as long as we run | |
6702 | * in the idle task. | |
6703 | * | |
6704 | * So complain bitterly if someone does call rcu_read_lock(), | |
6705 | * rcu_read_lock_bh() and so on from extended quiescent states. | |
6706 | */ | |
5c173eb8 | 6707 | if (!rcu_is_watching()) |
681fbec8 | 6708 | pr_warn("RCU used illegally from extended quiescent state!\n"); |
0464e937 | 6709 | |
0632eb3d | 6710 | lockdep_print_held_locks(curr); |
681fbec8 | 6711 | pr_warn("\nstack backtrace:\n"); |
0632eb3d | 6712 | dump_stack(); |
5a5d7e9b | 6713 | warn_rcu_exit(rcu); |
0632eb3d | 6714 | } |
b3fbab05 | 6715 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |