Commit | Line | Data |
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fbb9ce95 IM |
1 | /* |
2 | * kernel/lockdep.c | |
3 | * | |
4 | * Runtime locking correctness validator | |
5 | * | |
6 | * Started by Ingo Molnar: | |
7 | * | |
8 | * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
9 | * | |
10 | * this code maps all the lock dependencies as they occur in a live kernel | |
11 | * and will warn about the following classes of locking bugs: | |
12 | * | |
13 | * - lock inversion scenarios | |
14 | * - circular lock dependencies | |
15 | * - hardirq/softirq safe/unsafe locking bugs | |
16 | * | |
17 | * Bugs are reported even if the current locking scenario does not cause | |
18 | * any deadlock at this point. | |
19 | * | |
20 | * I.e. if anytime in the past two locks were taken in a different order, | |
21 | * even if it happened for another task, even if those were different | |
22 | * locks (but of the same class as this lock), this code will detect it. | |
23 | * | |
24 | * Thanks to Arjan van de Ven for coming up with the initial idea of | |
25 | * mapping lock dependencies runtime. | |
26 | */ | |
27 | #include <linux/mutex.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/delay.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/proc_fs.h> | |
32 | #include <linux/seq_file.h> | |
33 | #include <linux/spinlock.h> | |
34 | #include <linux/kallsyms.h> | |
35 | #include <linux/interrupt.h> | |
36 | #include <linux/stacktrace.h> | |
37 | #include <linux/debug_locks.h> | |
38 | #include <linux/irqflags.h> | |
99de055a | 39 | #include <linux/utsname.h> |
fbb9ce95 IM |
40 | |
41 | #include <asm/sections.h> | |
42 | ||
43 | #include "lockdep_internals.h" | |
44 | ||
45 | /* | |
46 | * hash_lock: protects the lockdep hashes and class/list/hash allocators. | |
47 | * | |
48 | * This is one of the rare exceptions where it's justified | |
49 | * to use a raw spinlock - we really dont want the spinlock | |
50 | * code to recurse back into the lockdep code. | |
51 | */ | |
52 | static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; | |
53 | ||
54 | static int lockdep_initialized; | |
55 | ||
56 | unsigned long nr_list_entries; | |
57 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; | |
58 | ||
59 | /* | |
60 | * Allocate a lockdep entry. (assumes hash_lock held, returns | |
61 | * with NULL on failure) | |
62 | */ | |
63 | static struct lock_list *alloc_list_entry(void) | |
64 | { | |
65 | if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { | |
66 | __raw_spin_unlock(&hash_lock); | |
67 | debug_locks_off(); | |
68 | printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n"); | |
69 | printk("turning off the locking correctness validator.\n"); | |
70 | return NULL; | |
71 | } | |
72 | return list_entries + nr_list_entries++; | |
73 | } | |
74 | ||
75 | /* | |
76 | * All data structures here are protected by the global debug_lock. | |
77 | * | |
78 | * Mutex key structs only get allocated, once during bootup, and never | |
79 | * get freed - this significantly simplifies the debugging code. | |
80 | */ | |
81 | unsigned long nr_lock_classes; | |
82 | static struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; | |
83 | ||
84 | /* | |
85 | * We keep a global list of all lock classes. The list only grows, | |
86 | * never shrinks. The list is only accessed with the lockdep | |
87 | * spinlock lock held. | |
88 | */ | |
89 | LIST_HEAD(all_lock_classes); | |
90 | ||
91 | /* | |
92 | * The lockdep classes are in a hash-table as well, for fast lookup: | |
93 | */ | |
94 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) | |
95 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) | |
96 | #define CLASSHASH_MASK (CLASSHASH_SIZE - 1) | |
97 | #define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK) | |
98 | #define classhashentry(key) (classhash_table + __classhashfn((key))) | |
99 | ||
100 | static struct list_head classhash_table[CLASSHASH_SIZE]; | |
101 | ||
102 | unsigned long nr_lock_chains; | |
103 | static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; | |
104 | ||
105 | /* | |
106 | * We put the lock dependency chains into a hash-table as well, to cache | |
107 | * their existence: | |
108 | */ | |
109 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) | |
110 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) | |
111 | #define CHAINHASH_MASK (CHAINHASH_SIZE - 1) | |
112 | #define __chainhashfn(chain) \ | |
113 | (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK) | |
114 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) | |
115 | ||
116 | static struct list_head chainhash_table[CHAINHASH_SIZE]; | |
117 | ||
118 | /* | |
119 | * The hash key of the lock dependency chains is a hash itself too: | |
120 | * it's a hash of all locks taken up to that lock, including that lock. | |
121 | * It's a 64-bit hash, because it's important for the keys to be | |
122 | * unique. | |
123 | */ | |
124 | #define iterate_chain_key(key1, key2) \ | |
03cbc358 IM |
125 | (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ |
126 | ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ | |
fbb9ce95 IM |
127 | (key2)) |
128 | ||
129 | void lockdep_off(void) | |
130 | { | |
131 | current->lockdep_recursion++; | |
132 | } | |
133 | ||
134 | EXPORT_SYMBOL(lockdep_off); | |
135 | ||
136 | void lockdep_on(void) | |
137 | { | |
138 | current->lockdep_recursion--; | |
139 | } | |
140 | ||
141 | EXPORT_SYMBOL(lockdep_on); | |
142 | ||
fbb9ce95 IM |
143 | /* |
144 | * Debugging switches: | |
145 | */ | |
146 | ||
147 | #define VERBOSE 0 | |
33e94e96 | 148 | #define VERY_VERBOSE 0 |
fbb9ce95 IM |
149 | |
150 | #if VERBOSE | |
151 | # define HARDIRQ_VERBOSE 1 | |
152 | # define SOFTIRQ_VERBOSE 1 | |
153 | #else | |
154 | # define HARDIRQ_VERBOSE 0 | |
155 | # define SOFTIRQ_VERBOSE 0 | |
156 | #endif | |
157 | ||
158 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE | |
159 | /* | |
160 | * Quick filtering for interesting events: | |
161 | */ | |
162 | static int class_filter(struct lock_class *class) | |
163 | { | |
f9829cce AK |
164 | #if 0 |
165 | /* Example */ | |
fbb9ce95 | 166 | if (class->name_version == 1 && |
f9829cce | 167 | !strcmp(class->name, "lockname")) |
fbb9ce95 IM |
168 | return 1; |
169 | if (class->name_version == 1 && | |
f9829cce | 170 | !strcmp(class->name, "&struct->lockfield")) |
fbb9ce95 | 171 | return 1; |
f9829cce | 172 | #endif |
a6640897 IM |
173 | /* Filter everything else. 1 would be to allow everything else */ |
174 | return 0; | |
fbb9ce95 IM |
175 | } |
176 | #endif | |
177 | ||
178 | static int verbose(struct lock_class *class) | |
179 | { | |
180 | #if VERBOSE | |
181 | return class_filter(class); | |
182 | #endif | |
183 | return 0; | |
184 | } | |
185 | ||
186 | #ifdef CONFIG_TRACE_IRQFLAGS | |
187 | ||
188 | static int hardirq_verbose(struct lock_class *class) | |
189 | { | |
190 | #if HARDIRQ_VERBOSE | |
191 | return class_filter(class); | |
192 | #endif | |
193 | return 0; | |
194 | } | |
195 | ||
196 | static int softirq_verbose(struct lock_class *class) | |
197 | { | |
198 | #if SOFTIRQ_VERBOSE | |
199 | return class_filter(class); | |
200 | #endif | |
201 | return 0; | |
202 | } | |
203 | ||
204 | #endif | |
205 | ||
206 | /* | |
207 | * Stack-trace: tightly packed array of stack backtrace | |
208 | * addresses. Protected by the hash_lock. | |
209 | */ | |
210 | unsigned long nr_stack_trace_entries; | |
211 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; | |
212 | ||
213 | static int save_trace(struct stack_trace *trace) | |
214 | { | |
215 | trace->nr_entries = 0; | |
216 | trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; | |
217 | trace->entries = stack_trace + nr_stack_trace_entries; | |
218 | ||
5a1b3999 AK |
219 | trace->skip = 3; |
220 | trace->all_contexts = 0; | |
221 | ||
222 | save_stack_trace(trace, NULL); | |
fbb9ce95 IM |
223 | |
224 | trace->max_entries = trace->nr_entries; | |
225 | ||
226 | nr_stack_trace_entries += trace->nr_entries; | |
910b1b2e JP |
227 | if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) { |
228 | __raw_spin_unlock(&hash_lock); | |
fbb9ce95 | 229 | return 0; |
910b1b2e | 230 | } |
fbb9ce95 IM |
231 | |
232 | if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) { | |
233 | __raw_spin_unlock(&hash_lock); | |
234 | if (debug_locks_off()) { | |
235 | printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); | |
236 | printk("turning off the locking correctness validator.\n"); | |
237 | dump_stack(); | |
238 | } | |
239 | return 0; | |
240 | } | |
241 | ||
242 | return 1; | |
243 | } | |
244 | ||
245 | unsigned int nr_hardirq_chains; | |
246 | unsigned int nr_softirq_chains; | |
247 | unsigned int nr_process_chains; | |
248 | unsigned int max_lockdep_depth; | |
249 | unsigned int max_recursion_depth; | |
250 | ||
251 | #ifdef CONFIG_DEBUG_LOCKDEP | |
252 | /* | |
253 | * We cannot printk in early bootup code. Not even early_printk() | |
254 | * might work. So we mark any initialization errors and printk | |
255 | * about it later on, in lockdep_info(). | |
256 | */ | |
257 | static int lockdep_init_error; | |
258 | ||
259 | /* | |
260 | * Various lockdep statistics: | |
261 | */ | |
262 | atomic_t chain_lookup_hits; | |
263 | atomic_t chain_lookup_misses; | |
264 | atomic_t hardirqs_on_events; | |
265 | atomic_t hardirqs_off_events; | |
266 | atomic_t redundant_hardirqs_on; | |
267 | atomic_t redundant_hardirqs_off; | |
268 | atomic_t softirqs_on_events; | |
269 | atomic_t softirqs_off_events; | |
270 | atomic_t redundant_softirqs_on; | |
271 | atomic_t redundant_softirqs_off; | |
272 | atomic_t nr_unused_locks; | |
273 | atomic_t nr_cyclic_checks; | |
274 | atomic_t nr_cyclic_check_recursions; | |
275 | atomic_t nr_find_usage_forwards_checks; | |
276 | atomic_t nr_find_usage_forwards_recursions; | |
277 | atomic_t nr_find_usage_backwards_checks; | |
278 | atomic_t nr_find_usage_backwards_recursions; | |
279 | # define debug_atomic_inc(ptr) atomic_inc(ptr) | |
280 | # define debug_atomic_dec(ptr) atomic_dec(ptr) | |
281 | # define debug_atomic_read(ptr) atomic_read(ptr) | |
282 | #else | |
283 | # define debug_atomic_inc(ptr) do { } while (0) | |
284 | # define debug_atomic_dec(ptr) do { } while (0) | |
285 | # define debug_atomic_read(ptr) 0 | |
286 | #endif | |
287 | ||
288 | /* | |
289 | * Locking printouts: | |
290 | */ | |
291 | ||
292 | static const char *usage_str[] = | |
293 | { | |
294 | [LOCK_USED] = "initial-use ", | |
295 | [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W", | |
296 | [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W", | |
297 | [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W", | |
298 | [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W", | |
299 | [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R", | |
300 | [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R", | |
301 | [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R", | |
302 | [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R", | |
303 | }; | |
304 | ||
305 | const char * __get_key_name(struct lockdep_subclass_key *key, char *str) | |
306 | { | |
307 | unsigned long offs, size; | |
308 | char *modname; | |
309 | ||
310 | return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str); | |
311 | } | |
312 | ||
313 | void | |
314 | get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4) | |
315 | { | |
316 | *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.'; | |
317 | ||
318 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) | |
319 | *c1 = '+'; | |
320 | else | |
321 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) | |
322 | *c1 = '-'; | |
323 | ||
324 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) | |
325 | *c2 = '+'; | |
326 | else | |
327 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) | |
328 | *c2 = '-'; | |
329 | ||
330 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
331 | *c3 = '-'; | |
332 | if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) { | |
333 | *c3 = '+'; | |
334 | if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) | |
335 | *c3 = '?'; | |
336 | } | |
337 | ||
338 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
339 | *c4 = '-'; | |
340 | if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) { | |
341 | *c4 = '+'; | |
342 | if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) | |
343 | *c4 = '?'; | |
344 | } | |
345 | } | |
346 | ||
347 | static void print_lock_name(struct lock_class *class) | |
348 | { | |
b23984d0 | 349 | char str[KSYM_NAME_LEN + 1], c1, c2, c3, c4; |
fbb9ce95 IM |
350 | const char *name; |
351 | ||
352 | get_usage_chars(class, &c1, &c2, &c3, &c4); | |
353 | ||
354 | name = class->name; | |
355 | if (!name) { | |
356 | name = __get_key_name(class->key, str); | |
357 | printk(" (%s", name); | |
358 | } else { | |
359 | printk(" (%s", name); | |
360 | if (class->name_version > 1) | |
361 | printk("#%d", class->name_version); | |
362 | if (class->subclass) | |
363 | printk("/%d", class->subclass); | |
364 | } | |
365 | printk("){%c%c%c%c}", c1, c2, c3, c4); | |
366 | } | |
367 | ||
368 | static void print_lockdep_cache(struct lockdep_map *lock) | |
369 | { | |
370 | const char *name; | |
b23984d0 | 371 | char str[KSYM_NAME_LEN + 1]; |
fbb9ce95 IM |
372 | |
373 | name = lock->name; | |
374 | if (!name) | |
375 | name = __get_key_name(lock->key->subkeys, str); | |
376 | ||
377 | printk("%s", name); | |
378 | } | |
379 | ||
380 | static void print_lock(struct held_lock *hlock) | |
381 | { | |
382 | print_lock_name(hlock->class); | |
383 | printk(", at: "); | |
384 | print_ip_sym(hlock->acquire_ip); | |
385 | } | |
386 | ||
387 | static void lockdep_print_held_locks(struct task_struct *curr) | |
388 | { | |
389 | int i, depth = curr->lockdep_depth; | |
390 | ||
391 | if (!depth) { | |
392 | printk("no locks held by %s/%d.\n", curr->comm, curr->pid); | |
393 | return; | |
394 | } | |
395 | printk("%d lock%s held by %s/%d:\n", | |
396 | depth, depth > 1 ? "s" : "", curr->comm, curr->pid); | |
397 | ||
398 | for (i = 0; i < depth; i++) { | |
399 | printk(" #%d: ", i); | |
400 | print_lock(curr->held_locks + i); | |
401 | } | |
402 | } | |
fbb9ce95 IM |
403 | |
404 | static void print_lock_class_header(struct lock_class *class, int depth) | |
405 | { | |
406 | int bit; | |
407 | ||
f9829cce | 408 | printk("%*s->", depth, ""); |
fbb9ce95 IM |
409 | print_lock_name(class); |
410 | printk(" ops: %lu", class->ops); | |
411 | printk(" {\n"); | |
412 | ||
413 | for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { | |
414 | if (class->usage_mask & (1 << bit)) { | |
415 | int len = depth; | |
416 | ||
f9829cce | 417 | len += printk("%*s %s", depth, "", usage_str[bit]); |
fbb9ce95 IM |
418 | len += printk(" at:\n"); |
419 | print_stack_trace(class->usage_traces + bit, len); | |
420 | } | |
421 | } | |
f9829cce | 422 | printk("%*s }\n", depth, ""); |
fbb9ce95 | 423 | |
f9829cce | 424 | printk("%*s ... key at: ",depth,""); |
fbb9ce95 IM |
425 | print_ip_sym((unsigned long)class->key); |
426 | } | |
427 | ||
428 | /* | |
429 | * printk all lock dependencies starting at <entry>: | |
430 | */ | |
431 | static void print_lock_dependencies(struct lock_class *class, int depth) | |
432 | { | |
433 | struct lock_list *entry; | |
434 | ||
435 | if (DEBUG_LOCKS_WARN_ON(depth >= 20)) | |
436 | return; | |
437 | ||
438 | print_lock_class_header(class, depth); | |
439 | ||
440 | list_for_each_entry(entry, &class->locks_after, entry) { | |
b23984d0 JP |
441 | if (DEBUG_LOCKS_WARN_ON(!entry->class)) |
442 | return; | |
443 | ||
fbb9ce95 IM |
444 | print_lock_dependencies(entry->class, depth + 1); |
445 | ||
f9829cce | 446 | printk("%*s ... acquired at:\n",depth,""); |
fbb9ce95 IM |
447 | print_stack_trace(&entry->trace, 2); |
448 | printk("\n"); | |
449 | } | |
450 | } | |
451 | ||
452 | /* | |
453 | * Add a new dependency to the head of the list: | |
454 | */ | |
455 | static int add_lock_to_list(struct lock_class *class, struct lock_class *this, | |
456 | struct list_head *head, unsigned long ip) | |
457 | { | |
458 | struct lock_list *entry; | |
459 | /* | |
460 | * Lock not present yet - get a new dependency struct and | |
461 | * add it to the list: | |
462 | */ | |
463 | entry = alloc_list_entry(); | |
464 | if (!entry) | |
465 | return 0; | |
466 | ||
467 | entry->class = this; | |
910b1b2e JP |
468 | if (!save_trace(&entry->trace)) |
469 | return 0; | |
fbb9ce95 IM |
470 | |
471 | /* | |
472 | * Since we never remove from the dependency list, the list can | |
473 | * be walked lockless by other CPUs, it's only allocation | |
474 | * that must be protected by the spinlock. But this also means | |
475 | * we must make new entries visible only once writes to the | |
476 | * entry become visible - hence the RCU op: | |
477 | */ | |
478 | list_add_tail_rcu(&entry->entry, head); | |
479 | ||
480 | return 1; | |
481 | } | |
482 | ||
483 | /* | |
484 | * Recursive, forwards-direction lock-dependency checking, used for | |
485 | * both noncyclic checking and for hardirq-unsafe/softirq-unsafe | |
486 | * checking. | |
487 | * | |
488 | * (to keep the stackframe of the recursive functions small we | |
489 | * use these global variables, and we also mark various helper | |
490 | * functions as noinline.) | |
491 | */ | |
492 | static struct held_lock *check_source, *check_target; | |
493 | ||
494 | /* | |
495 | * Print a dependency chain entry (this is only done when a deadlock | |
496 | * has been detected): | |
497 | */ | |
498 | static noinline int | |
499 | print_circular_bug_entry(struct lock_list *target, unsigned int depth) | |
500 | { | |
501 | if (debug_locks_silent) | |
502 | return 0; | |
503 | printk("\n-> #%u", depth); | |
504 | print_lock_name(target->class); | |
505 | printk(":\n"); | |
506 | print_stack_trace(&target->trace, 6); | |
507 | ||
508 | return 0; | |
509 | } | |
510 | ||
99de055a DJ |
511 | static void print_kernel_version(void) |
512 | { | |
96b644bd SH |
513 | printk("%s %.*s\n", init_utsname()->release, |
514 | (int)strcspn(init_utsname()->version, " "), | |
515 | init_utsname()->version); | |
99de055a DJ |
516 | } |
517 | ||
fbb9ce95 IM |
518 | /* |
519 | * When a circular dependency is detected, print the | |
520 | * header first: | |
521 | */ | |
522 | static noinline int | |
523 | print_circular_bug_header(struct lock_list *entry, unsigned int depth) | |
524 | { | |
525 | struct task_struct *curr = current; | |
526 | ||
527 | __raw_spin_unlock(&hash_lock); | |
528 | debug_locks_off(); | |
529 | if (debug_locks_silent) | |
530 | return 0; | |
531 | ||
532 | printk("\n=======================================================\n"); | |
533 | printk( "[ INFO: possible circular locking dependency detected ]\n"); | |
99de055a | 534 | print_kernel_version(); |
fbb9ce95 IM |
535 | printk( "-------------------------------------------------------\n"); |
536 | printk("%s/%d is trying to acquire lock:\n", | |
537 | curr->comm, curr->pid); | |
538 | print_lock(check_source); | |
539 | printk("\nbut task is already holding lock:\n"); | |
540 | print_lock(check_target); | |
541 | printk("\nwhich lock already depends on the new lock.\n\n"); | |
542 | printk("\nthe existing dependency chain (in reverse order) is:\n"); | |
543 | ||
544 | print_circular_bug_entry(entry, depth); | |
545 | ||
546 | return 0; | |
547 | } | |
548 | ||
549 | static noinline int print_circular_bug_tail(void) | |
550 | { | |
551 | struct task_struct *curr = current; | |
552 | struct lock_list this; | |
553 | ||
554 | if (debug_locks_silent) | |
555 | return 0; | |
556 | ||
910b1b2e JP |
557 | /* hash_lock unlocked by the header */ |
558 | __raw_spin_lock(&hash_lock); | |
fbb9ce95 | 559 | this.class = check_source->class; |
910b1b2e JP |
560 | if (!save_trace(&this.trace)) |
561 | return 0; | |
562 | __raw_spin_unlock(&hash_lock); | |
fbb9ce95 IM |
563 | print_circular_bug_entry(&this, 0); |
564 | ||
565 | printk("\nother info that might help us debug this:\n\n"); | |
566 | lockdep_print_held_locks(curr); | |
567 | ||
568 | printk("\nstack backtrace:\n"); | |
569 | dump_stack(); | |
570 | ||
571 | return 0; | |
572 | } | |
573 | ||
ca268c69 IM |
574 | #define RECURSION_LIMIT 40 |
575 | ||
fbb9ce95 IM |
576 | static int noinline print_infinite_recursion_bug(void) |
577 | { | |
578 | __raw_spin_unlock(&hash_lock); | |
579 | DEBUG_LOCKS_WARN_ON(1); | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
584 | /* | |
585 | * Prove that the dependency graph starting at <entry> can not | |
586 | * lead to <target>. Print an error and return 0 if it does. | |
587 | */ | |
588 | static noinline int | |
589 | check_noncircular(struct lock_class *source, unsigned int depth) | |
590 | { | |
591 | struct lock_list *entry; | |
592 | ||
593 | debug_atomic_inc(&nr_cyclic_check_recursions); | |
594 | if (depth > max_recursion_depth) | |
595 | max_recursion_depth = depth; | |
ca268c69 | 596 | if (depth >= RECURSION_LIMIT) |
fbb9ce95 IM |
597 | return print_infinite_recursion_bug(); |
598 | /* | |
599 | * Check this lock's dependency list: | |
600 | */ | |
601 | list_for_each_entry(entry, &source->locks_after, entry) { | |
602 | if (entry->class == check_target->class) | |
603 | return print_circular_bug_header(entry, depth+1); | |
604 | debug_atomic_inc(&nr_cyclic_checks); | |
605 | if (!check_noncircular(entry->class, depth+1)) | |
606 | return print_circular_bug_entry(entry, depth+1); | |
607 | } | |
608 | return 1; | |
609 | } | |
610 | ||
611 | static int very_verbose(struct lock_class *class) | |
612 | { | |
613 | #if VERY_VERBOSE | |
614 | return class_filter(class); | |
615 | #endif | |
616 | return 0; | |
617 | } | |
618 | #ifdef CONFIG_TRACE_IRQFLAGS | |
619 | ||
620 | /* | |
621 | * Forwards and backwards subgraph searching, for the purposes of | |
622 | * proving that two subgraphs can be connected by a new dependency | |
623 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. | |
624 | */ | |
625 | static enum lock_usage_bit find_usage_bit; | |
626 | static struct lock_class *forwards_match, *backwards_match; | |
627 | ||
628 | /* | |
629 | * Find a node in the forwards-direction dependency sub-graph starting | |
630 | * at <source> that matches <find_usage_bit>. | |
631 | * | |
632 | * Return 2 if such a node exists in the subgraph, and put that node | |
633 | * into <forwards_match>. | |
634 | * | |
635 | * Return 1 otherwise and keep <forwards_match> unchanged. | |
636 | * Return 0 on error. | |
637 | */ | |
638 | static noinline int | |
639 | find_usage_forwards(struct lock_class *source, unsigned int depth) | |
640 | { | |
641 | struct lock_list *entry; | |
642 | int ret; | |
643 | ||
644 | if (depth > max_recursion_depth) | |
645 | max_recursion_depth = depth; | |
ca268c69 | 646 | if (depth >= RECURSION_LIMIT) |
fbb9ce95 IM |
647 | return print_infinite_recursion_bug(); |
648 | ||
649 | debug_atomic_inc(&nr_find_usage_forwards_checks); | |
650 | if (source->usage_mask & (1 << find_usage_bit)) { | |
651 | forwards_match = source; | |
652 | return 2; | |
653 | } | |
654 | ||
655 | /* | |
656 | * Check this lock's dependency list: | |
657 | */ | |
658 | list_for_each_entry(entry, &source->locks_after, entry) { | |
659 | debug_atomic_inc(&nr_find_usage_forwards_recursions); | |
660 | ret = find_usage_forwards(entry->class, depth+1); | |
661 | if (ret == 2 || ret == 0) | |
662 | return ret; | |
663 | } | |
664 | return 1; | |
665 | } | |
666 | ||
667 | /* | |
668 | * Find a node in the backwards-direction dependency sub-graph starting | |
669 | * at <source> that matches <find_usage_bit>. | |
670 | * | |
671 | * Return 2 if such a node exists in the subgraph, and put that node | |
672 | * into <backwards_match>. | |
673 | * | |
674 | * Return 1 otherwise and keep <backwards_match> unchanged. | |
675 | * Return 0 on error. | |
676 | */ | |
677 | static noinline int | |
678 | find_usage_backwards(struct lock_class *source, unsigned int depth) | |
679 | { | |
680 | struct lock_list *entry; | |
681 | int ret; | |
682 | ||
683 | if (depth > max_recursion_depth) | |
684 | max_recursion_depth = depth; | |
ca268c69 | 685 | if (depth >= RECURSION_LIMIT) |
fbb9ce95 IM |
686 | return print_infinite_recursion_bug(); |
687 | ||
688 | debug_atomic_inc(&nr_find_usage_backwards_checks); | |
689 | if (source->usage_mask & (1 << find_usage_bit)) { | |
690 | backwards_match = source; | |
691 | return 2; | |
692 | } | |
693 | ||
694 | /* | |
695 | * Check this lock's dependency list: | |
696 | */ | |
697 | list_for_each_entry(entry, &source->locks_before, entry) { | |
698 | debug_atomic_inc(&nr_find_usage_backwards_recursions); | |
699 | ret = find_usage_backwards(entry->class, depth+1); | |
700 | if (ret == 2 || ret == 0) | |
701 | return ret; | |
702 | } | |
703 | return 1; | |
704 | } | |
705 | ||
706 | static int | |
707 | print_bad_irq_dependency(struct task_struct *curr, | |
708 | struct held_lock *prev, | |
709 | struct held_lock *next, | |
710 | enum lock_usage_bit bit1, | |
711 | enum lock_usage_bit bit2, | |
712 | const char *irqclass) | |
713 | { | |
714 | __raw_spin_unlock(&hash_lock); | |
715 | debug_locks_off(); | |
716 | if (debug_locks_silent) | |
717 | return 0; | |
718 | ||
719 | printk("\n======================================================\n"); | |
720 | printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n", | |
721 | irqclass, irqclass); | |
99de055a | 722 | print_kernel_version(); |
fbb9ce95 IM |
723 | printk( "------------------------------------------------------\n"); |
724 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", | |
725 | curr->comm, curr->pid, | |
726 | curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, | |
727 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, | |
728 | curr->hardirqs_enabled, | |
729 | curr->softirqs_enabled); | |
730 | print_lock(next); | |
731 | ||
732 | printk("\nand this task is already holding:\n"); | |
733 | print_lock(prev); | |
734 | printk("which would create a new lock dependency:\n"); | |
735 | print_lock_name(prev->class); | |
736 | printk(" ->"); | |
737 | print_lock_name(next->class); | |
738 | printk("\n"); | |
739 | ||
740 | printk("\nbut this new dependency connects a %s-irq-safe lock:\n", | |
741 | irqclass); | |
742 | print_lock_name(backwards_match); | |
743 | printk("\n... which became %s-irq-safe at:\n", irqclass); | |
744 | ||
745 | print_stack_trace(backwards_match->usage_traces + bit1, 1); | |
746 | ||
747 | printk("\nto a %s-irq-unsafe lock:\n", irqclass); | |
748 | print_lock_name(forwards_match); | |
749 | printk("\n... which became %s-irq-unsafe at:\n", irqclass); | |
750 | printk("..."); | |
751 | ||
752 | print_stack_trace(forwards_match->usage_traces + bit2, 1); | |
753 | ||
754 | printk("\nother info that might help us debug this:\n\n"); | |
755 | lockdep_print_held_locks(curr); | |
756 | ||
757 | printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass); | |
758 | print_lock_dependencies(backwards_match, 0); | |
759 | ||
760 | printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass); | |
761 | print_lock_dependencies(forwards_match, 0); | |
762 | ||
763 | printk("\nstack backtrace:\n"); | |
764 | dump_stack(); | |
765 | ||
766 | return 0; | |
767 | } | |
768 | ||
769 | static int | |
770 | check_usage(struct task_struct *curr, struct held_lock *prev, | |
771 | struct held_lock *next, enum lock_usage_bit bit_backwards, | |
772 | enum lock_usage_bit bit_forwards, const char *irqclass) | |
773 | { | |
774 | int ret; | |
775 | ||
776 | find_usage_bit = bit_backwards; | |
777 | /* fills in <backwards_match> */ | |
778 | ret = find_usage_backwards(prev->class, 0); | |
779 | if (!ret || ret == 1) | |
780 | return ret; | |
781 | ||
782 | find_usage_bit = bit_forwards; | |
783 | ret = find_usage_forwards(next->class, 0); | |
784 | if (!ret || ret == 1) | |
785 | return ret; | |
786 | /* ret == 2 */ | |
787 | return print_bad_irq_dependency(curr, prev, next, | |
788 | bit_backwards, bit_forwards, irqclass); | |
789 | } | |
790 | ||
791 | #endif | |
792 | ||
793 | static int | |
794 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, | |
795 | struct held_lock *next) | |
796 | { | |
797 | debug_locks_off(); | |
798 | __raw_spin_unlock(&hash_lock); | |
799 | if (debug_locks_silent) | |
800 | return 0; | |
801 | ||
802 | printk("\n=============================================\n"); | |
803 | printk( "[ INFO: possible recursive locking detected ]\n"); | |
99de055a | 804 | print_kernel_version(); |
fbb9ce95 IM |
805 | printk( "---------------------------------------------\n"); |
806 | printk("%s/%d is trying to acquire lock:\n", | |
807 | curr->comm, curr->pid); | |
808 | print_lock(next); | |
809 | printk("\nbut task is already holding lock:\n"); | |
810 | print_lock(prev); | |
811 | ||
812 | printk("\nother info that might help us debug this:\n"); | |
813 | lockdep_print_held_locks(curr); | |
814 | ||
815 | printk("\nstack backtrace:\n"); | |
816 | dump_stack(); | |
817 | ||
818 | return 0; | |
819 | } | |
820 | ||
821 | /* | |
822 | * Check whether we are holding such a class already. | |
823 | * | |
824 | * (Note that this has to be done separately, because the graph cannot | |
825 | * detect such classes of deadlocks.) | |
826 | * | |
827 | * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read | |
828 | */ | |
829 | static int | |
830 | check_deadlock(struct task_struct *curr, struct held_lock *next, | |
831 | struct lockdep_map *next_instance, int read) | |
832 | { | |
833 | struct held_lock *prev; | |
834 | int i; | |
835 | ||
836 | for (i = 0; i < curr->lockdep_depth; i++) { | |
837 | prev = curr->held_locks + i; | |
838 | if (prev->class != next->class) | |
839 | continue; | |
840 | /* | |
841 | * Allow read-after-read recursion of the same | |
6c9076ec | 842 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
fbb9ce95 | 843 | */ |
6c9076ec | 844 | if ((read == 2) && prev->read) |
fbb9ce95 IM |
845 | return 2; |
846 | return print_deadlock_bug(curr, prev, next); | |
847 | } | |
848 | return 1; | |
849 | } | |
850 | ||
851 | /* | |
852 | * There was a chain-cache miss, and we are about to add a new dependency | |
853 | * to a previous lock. We recursively validate the following rules: | |
854 | * | |
855 | * - would the adding of the <prev> -> <next> dependency create a | |
856 | * circular dependency in the graph? [== circular deadlock] | |
857 | * | |
858 | * - does the new prev->next dependency connect any hardirq-safe lock | |
859 | * (in the full backwards-subgraph starting at <prev>) with any | |
860 | * hardirq-unsafe lock (in the full forwards-subgraph starting at | |
861 | * <next>)? [== illegal lock inversion with hardirq contexts] | |
862 | * | |
863 | * - does the new prev->next dependency connect any softirq-safe lock | |
864 | * (in the full backwards-subgraph starting at <prev>) with any | |
865 | * softirq-unsafe lock (in the full forwards-subgraph starting at | |
866 | * <next>)? [== illegal lock inversion with softirq contexts] | |
867 | * | |
868 | * any of these scenarios could lead to a deadlock. | |
869 | * | |
870 | * Then if all the validations pass, we add the forwards and backwards | |
871 | * dependency. | |
872 | */ | |
873 | static int | |
874 | check_prev_add(struct task_struct *curr, struct held_lock *prev, | |
875 | struct held_lock *next) | |
876 | { | |
877 | struct lock_list *entry; | |
878 | int ret; | |
879 | ||
880 | /* | |
881 | * Prove that the new <prev> -> <next> dependency would not | |
882 | * create a circular dependency in the graph. (We do this by | |
883 | * forward-recursing into the graph starting at <next>, and | |
884 | * checking whether we can reach <prev>.) | |
885 | * | |
886 | * We are using global variables to control the recursion, to | |
887 | * keep the stackframe size of the recursive functions low: | |
888 | */ | |
889 | check_source = next; | |
890 | check_target = prev; | |
891 | if (!(check_noncircular(next->class, 0))) | |
892 | return print_circular_bug_tail(); | |
893 | ||
894 | #ifdef CONFIG_TRACE_IRQFLAGS | |
895 | /* | |
896 | * Prove that the new dependency does not connect a hardirq-safe | |
897 | * lock with a hardirq-unsafe lock - to achieve this we search | |
898 | * the backwards-subgraph starting at <prev>, and the | |
899 | * forwards-subgraph starting at <next>: | |
900 | */ | |
901 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ, | |
902 | LOCK_ENABLED_HARDIRQS, "hard")) | |
903 | return 0; | |
904 | ||
905 | /* | |
906 | * Prove that the new dependency does not connect a hardirq-safe-read | |
907 | * lock with a hardirq-unsafe lock - to achieve this we search | |
908 | * the backwards-subgraph starting at <prev>, and the | |
909 | * forwards-subgraph starting at <next>: | |
910 | */ | |
911 | if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ, | |
912 | LOCK_ENABLED_HARDIRQS, "hard-read")) | |
913 | return 0; | |
914 | ||
915 | /* | |
916 | * Prove that the new dependency does not connect a softirq-safe | |
917 | * lock with a softirq-unsafe lock - to achieve this we search | |
918 | * the backwards-subgraph starting at <prev>, and the | |
919 | * forwards-subgraph starting at <next>: | |
920 | */ | |
921 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ, | |
922 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
923 | return 0; | |
924 | /* | |
925 | * Prove that the new dependency does not connect a softirq-safe-read | |
926 | * lock with a softirq-unsafe lock - to achieve this we search | |
927 | * the backwards-subgraph starting at <prev>, and the | |
928 | * forwards-subgraph starting at <next>: | |
929 | */ | |
930 | if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ, | |
931 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
932 | return 0; | |
933 | #endif | |
934 | /* | |
935 | * For recursive read-locks we do all the dependency checks, | |
936 | * but we dont store read-triggered dependencies (only | |
937 | * write-triggered dependencies). This ensures that only the | |
938 | * write-side dependencies matter, and that if for example a | |
939 | * write-lock never takes any other locks, then the reads are | |
940 | * equivalent to a NOP. | |
941 | */ | |
942 | if (next->read == 2 || prev->read == 2) | |
943 | return 1; | |
944 | /* | |
945 | * Is the <prev> -> <next> dependency already present? | |
946 | * | |
947 | * (this may occur even though this is a new chain: consider | |
948 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 | |
949 | * chains - the second one will be new, but L1 already has | |
950 | * L2 added to its dependency list, due to the first chain.) | |
951 | */ | |
952 | list_for_each_entry(entry, &prev->class->locks_after, entry) { | |
953 | if (entry->class == next->class) | |
954 | return 2; | |
955 | } | |
956 | ||
957 | /* | |
958 | * Ok, all validations passed, add the new lock | |
959 | * to the previous lock's dependency list: | |
960 | */ | |
961 | ret = add_lock_to_list(prev->class, next->class, | |
962 | &prev->class->locks_after, next->acquire_ip); | |
963 | if (!ret) | |
964 | return 0; | |
910b1b2e | 965 | |
fbb9ce95 IM |
966 | ret = add_lock_to_list(next->class, prev->class, |
967 | &next->class->locks_before, next->acquire_ip); | |
910b1b2e JP |
968 | if (!ret) |
969 | return 0; | |
fbb9ce95 IM |
970 | |
971 | /* | |
972 | * Debugging printouts: | |
973 | */ | |
974 | if (verbose(prev->class) || verbose(next->class)) { | |
975 | __raw_spin_unlock(&hash_lock); | |
976 | printk("\n new dependency: "); | |
977 | print_lock_name(prev->class); | |
978 | printk(" => "); | |
979 | print_lock_name(next->class); | |
980 | printk("\n"); | |
981 | dump_stack(); | |
982 | __raw_spin_lock(&hash_lock); | |
983 | } | |
984 | return 1; | |
985 | } | |
986 | ||
987 | /* | |
988 | * Add the dependency to all directly-previous locks that are 'relevant'. | |
989 | * The ones that are relevant are (in increasing distance from curr): | |
990 | * all consecutive trylock entries and the final non-trylock entry - or | |
991 | * the end of this context's lock-chain - whichever comes first. | |
992 | */ | |
993 | static int | |
994 | check_prevs_add(struct task_struct *curr, struct held_lock *next) | |
995 | { | |
996 | int depth = curr->lockdep_depth; | |
997 | struct held_lock *hlock; | |
998 | ||
999 | /* | |
1000 | * Debugging checks. | |
1001 | * | |
1002 | * Depth must not be zero for a non-head lock: | |
1003 | */ | |
1004 | if (!depth) | |
1005 | goto out_bug; | |
1006 | /* | |
1007 | * At least two relevant locks must exist for this | |
1008 | * to be a head: | |
1009 | */ | |
1010 | if (curr->held_locks[depth].irq_context != | |
1011 | curr->held_locks[depth-1].irq_context) | |
1012 | goto out_bug; | |
1013 | ||
1014 | for (;;) { | |
1015 | hlock = curr->held_locks + depth-1; | |
1016 | /* | |
1017 | * Only non-recursive-read entries get new dependencies | |
1018 | * added: | |
1019 | */ | |
1020 | if (hlock->read != 2) { | |
910b1b2e JP |
1021 | if (!check_prev_add(curr, hlock, next)) |
1022 | return 0; | |
fbb9ce95 IM |
1023 | /* |
1024 | * Stop after the first non-trylock entry, | |
1025 | * as non-trylock entries have added their | |
1026 | * own direct dependencies already, so this | |
1027 | * lock is connected to them indirectly: | |
1028 | */ | |
1029 | if (!hlock->trylock) | |
1030 | break; | |
1031 | } | |
1032 | depth--; | |
1033 | /* | |
1034 | * End of lock-stack? | |
1035 | */ | |
1036 | if (!depth) | |
1037 | break; | |
1038 | /* | |
1039 | * Stop the search if we cross into another context: | |
1040 | */ | |
1041 | if (curr->held_locks[depth].irq_context != | |
1042 | curr->held_locks[depth-1].irq_context) | |
1043 | break; | |
1044 | } | |
1045 | return 1; | |
1046 | out_bug: | |
1047 | __raw_spin_unlock(&hash_lock); | |
1048 | DEBUG_LOCKS_WARN_ON(1); | |
1049 | ||
1050 | return 0; | |
1051 | } | |
1052 | ||
1053 | ||
1054 | /* | |
1055 | * Is this the address of a static object: | |
1056 | */ | |
1057 | static int static_obj(void *obj) | |
1058 | { | |
1059 | unsigned long start = (unsigned long) &_stext, | |
1060 | end = (unsigned long) &_end, | |
1061 | addr = (unsigned long) obj; | |
1062 | #ifdef CONFIG_SMP | |
1063 | int i; | |
1064 | #endif | |
1065 | ||
1066 | /* | |
1067 | * static variable? | |
1068 | */ | |
1069 | if ((addr >= start) && (addr < end)) | |
1070 | return 1; | |
1071 | ||
1072 | #ifdef CONFIG_SMP | |
1073 | /* | |
1074 | * percpu var? | |
1075 | */ | |
1076 | for_each_possible_cpu(i) { | |
1077 | start = (unsigned long) &__per_cpu_start + per_cpu_offset(i); | |
1ff56830 IM |
1078 | end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM |
1079 | + per_cpu_offset(i); | |
fbb9ce95 IM |
1080 | |
1081 | if ((addr >= start) && (addr < end)) | |
1082 | return 1; | |
1083 | } | |
1084 | #endif | |
1085 | ||
1086 | /* | |
1087 | * module var? | |
1088 | */ | |
1089 | return is_module_address(addr); | |
1090 | } | |
1091 | ||
1092 | /* | |
1093 | * To make lock name printouts unique, we calculate a unique | |
1094 | * class->name_version generation counter: | |
1095 | */ | |
1096 | static int count_matching_names(struct lock_class *new_class) | |
1097 | { | |
1098 | struct lock_class *class; | |
1099 | int count = 0; | |
1100 | ||
1101 | if (!new_class->name) | |
1102 | return 0; | |
1103 | ||
1104 | list_for_each_entry(class, &all_lock_classes, lock_entry) { | |
1105 | if (new_class->key - new_class->subclass == class->key) | |
1106 | return class->name_version; | |
1107 | if (class->name && !strcmp(class->name, new_class->name)) | |
1108 | count = max(count, class->name_version); | |
1109 | } | |
1110 | ||
1111 | return count + 1; | |
1112 | } | |
1113 | ||
fbb9ce95 IM |
1114 | /* |
1115 | * Register a lock's class in the hash-table, if the class is not present | |
1116 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1117 | * itself, so actual lookup of the hash should be once per lock object. | |
1118 | */ | |
1119 | static inline struct lock_class * | |
d6d897ce | 1120 | look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) |
fbb9ce95 IM |
1121 | { |
1122 | struct lockdep_subclass_key *key; | |
1123 | struct list_head *hash_head; | |
1124 | struct lock_class *class; | |
1125 | ||
1126 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1127 | /* | |
1128 | * If the architecture calls into lockdep before initializing | |
1129 | * the hashes then we'll warn about it later. (we cannot printk | |
1130 | * right now) | |
1131 | */ | |
1132 | if (unlikely(!lockdep_initialized)) { | |
1133 | lockdep_init(); | |
1134 | lockdep_init_error = 1; | |
1135 | } | |
1136 | #endif | |
1137 | ||
1138 | /* | |
1139 | * Static locks do not have their class-keys yet - for them the key | |
1140 | * is the lock object itself: | |
1141 | */ | |
1142 | if (unlikely(!lock->key)) | |
1143 | lock->key = (void *)lock; | |
1144 | ||
1145 | /* | |
1146 | * NOTE: the class-key must be unique. For dynamic locks, a static | |
1147 | * lock_class_key variable is passed in through the mutex_init() | |
1148 | * (or spin_lock_init()) call - which acts as the key. For static | |
1149 | * locks we use the lock object itself as the key. | |
1150 | */ | |
3dc3099a | 1151 | BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(struct lock_class)); |
fbb9ce95 IM |
1152 | |
1153 | key = lock->key->subkeys + subclass; | |
1154 | ||
1155 | hash_head = classhashentry(key); | |
1156 | ||
1157 | /* | |
1158 | * We can walk the hash lockfree, because the hash only | |
1159 | * grows, and we are careful when adding entries to the end: | |
1160 | */ | |
1161 | list_for_each_entry(class, hash_head, hash_entry) | |
1162 | if (class->key == key) | |
d6d897ce IM |
1163 | return class; |
1164 | ||
1165 | return NULL; | |
1166 | } | |
1167 | ||
1168 | /* | |
1169 | * Register a lock's class in the hash-table, if the class is not present | |
1170 | * yet. Otherwise we look it up. We cache the result in the lock object | |
1171 | * itself, so actual lookup of the hash should be once per lock object. | |
1172 | */ | |
1173 | static inline struct lock_class * | |
4dfbb9d8 | 1174 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
d6d897ce IM |
1175 | { |
1176 | struct lockdep_subclass_key *key; | |
1177 | struct list_head *hash_head; | |
1178 | struct lock_class *class; | |
70e45067 | 1179 | unsigned long flags; |
d6d897ce IM |
1180 | |
1181 | class = look_up_lock_class(lock, subclass); | |
1182 | if (likely(class)) | |
1183 | return class; | |
fbb9ce95 IM |
1184 | |
1185 | /* | |
1186 | * Debug-check: all keys must be persistent! | |
1187 | */ | |
1188 | if (!static_obj(lock->key)) { | |
1189 | debug_locks_off(); | |
1190 | printk("INFO: trying to register non-static key.\n"); | |
1191 | printk("the code is fine but needs lockdep annotation.\n"); | |
1192 | printk("turning off the locking correctness validator.\n"); | |
1193 | dump_stack(); | |
1194 | ||
1195 | return NULL; | |
1196 | } | |
1197 | ||
d6d897ce IM |
1198 | key = lock->key->subkeys + subclass; |
1199 | hash_head = classhashentry(key); | |
1200 | ||
70e45067 | 1201 | raw_local_irq_save(flags); |
fbb9ce95 IM |
1202 | __raw_spin_lock(&hash_lock); |
1203 | /* | |
1204 | * We have to do the hash-walk again, to avoid races | |
1205 | * with another CPU: | |
1206 | */ | |
1207 | list_for_each_entry(class, hash_head, hash_entry) | |
1208 | if (class->key == key) | |
1209 | goto out_unlock_set; | |
1210 | /* | |
1211 | * Allocate a new key from the static array, and add it to | |
1212 | * the hash: | |
1213 | */ | |
1214 | if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { | |
1215 | __raw_spin_unlock(&hash_lock); | |
70e45067 | 1216 | raw_local_irq_restore(flags); |
fbb9ce95 IM |
1217 | debug_locks_off(); |
1218 | printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); | |
1219 | printk("turning off the locking correctness validator.\n"); | |
1220 | return NULL; | |
1221 | } | |
1222 | class = lock_classes + nr_lock_classes++; | |
1223 | debug_atomic_inc(&nr_unused_locks); | |
1224 | class->key = key; | |
1225 | class->name = lock->name; | |
1226 | class->subclass = subclass; | |
1227 | INIT_LIST_HEAD(&class->lock_entry); | |
1228 | INIT_LIST_HEAD(&class->locks_before); | |
1229 | INIT_LIST_HEAD(&class->locks_after); | |
1230 | class->name_version = count_matching_names(class); | |
1231 | /* | |
1232 | * We use RCU's safe list-add method to make | |
1233 | * parallel walking of the hash-list safe: | |
1234 | */ | |
1235 | list_add_tail_rcu(&class->hash_entry, hash_head); | |
1236 | ||
1237 | if (verbose(class)) { | |
1238 | __raw_spin_unlock(&hash_lock); | |
70e45067 | 1239 | raw_local_irq_restore(flags); |
fbb9ce95 IM |
1240 | printk("\nnew class %p: %s", class->key, class->name); |
1241 | if (class->name_version > 1) | |
1242 | printk("#%d", class->name_version); | |
1243 | printk("\n"); | |
1244 | dump_stack(); | |
70e45067 | 1245 | raw_local_irq_save(flags); |
fbb9ce95 IM |
1246 | __raw_spin_lock(&hash_lock); |
1247 | } | |
1248 | out_unlock_set: | |
1249 | __raw_spin_unlock(&hash_lock); | |
70e45067 | 1250 | raw_local_irq_restore(flags); |
fbb9ce95 | 1251 | |
4dfbb9d8 | 1252 | if (!subclass || force) |
d6d897ce | 1253 | lock->class_cache = class; |
fbb9ce95 IM |
1254 | |
1255 | DEBUG_LOCKS_WARN_ON(class->subclass != subclass); | |
1256 | ||
1257 | return class; | |
1258 | } | |
1259 | ||
1260 | /* | |
1261 | * Look up a dependency chain. If the key is not present yet then | |
1262 | * add it and return 0 - in this case the new dependency chain is | |
1263 | * validated. If the key is already hashed, return 1. | |
1264 | */ | |
81fc685a | 1265 | static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class) |
fbb9ce95 IM |
1266 | { |
1267 | struct list_head *hash_head = chainhashentry(chain_key); | |
1268 | struct lock_chain *chain; | |
1269 | ||
1270 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); | |
1271 | /* | |
1272 | * We can walk it lock-free, because entries only get added | |
1273 | * to the hash: | |
1274 | */ | |
1275 | list_for_each_entry(chain, hash_head, entry) { | |
1276 | if (chain->chain_key == chain_key) { | |
1277 | cache_hit: | |
1278 | debug_atomic_inc(&chain_lookup_hits); | |
81fc685a IM |
1279 | if (very_verbose(class)) |
1280 | printk("\nhash chain already cached, key: %016Lx tail class: [%p] %s\n", chain_key, class->key, class->name); | |
fbb9ce95 IM |
1281 | return 0; |
1282 | } | |
1283 | } | |
81fc685a IM |
1284 | if (very_verbose(class)) |
1285 | printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", chain_key, class->key, class->name); | |
fbb9ce95 IM |
1286 | /* |
1287 | * Allocate a new chain entry from the static array, and add | |
1288 | * it to the hash: | |
1289 | */ | |
1290 | __raw_spin_lock(&hash_lock); | |
1291 | /* | |
1292 | * We have to walk the chain again locked - to avoid duplicates: | |
1293 | */ | |
1294 | list_for_each_entry(chain, hash_head, entry) { | |
1295 | if (chain->chain_key == chain_key) { | |
1296 | __raw_spin_unlock(&hash_lock); | |
1297 | goto cache_hit; | |
1298 | } | |
1299 | } | |
1300 | if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { | |
1301 | __raw_spin_unlock(&hash_lock); | |
1302 | debug_locks_off(); | |
1303 | printk("BUG: MAX_LOCKDEP_CHAINS too low!\n"); | |
1304 | printk("turning off the locking correctness validator.\n"); | |
1305 | return 0; | |
1306 | } | |
1307 | chain = lock_chains + nr_lock_chains++; | |
1308 | chain->chain_key = chain_key; | |
1309 | list_add_tail_rcu(&chain->entry, hash_head); | |
1310 | debug_atomic_inc(&chain_lookup_misses); | |
1311 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1312 | if (current->hardirq_context) | |
1313 | nr_hardirq_chains++; | |
1314 | else { | |
1315 | if (current->softirq_context) | |
1316 | nr_softirq_chains++; | |
1317 | else | |
1318 | nr_process_chains++; | |
1319 | } | |
1320 | #else | |
1321 | nr_process_chains++; | |
1322 | #endif | |
1323 | ||
1324 | return 1; | |
1325 | } | |
1326 | ||
1327 | /* | |
1328 | * We are building curr_chain_key incrementally, so double-check | |
1329 | * it from scratch, to make sure that it's done correctly: | |
1330 | */ | |
1331 | static void check_chain_key(struct task_struct *curr) | |
1332 | { | |
1333 | #ifdef CONFIG_DEBUG_LOCKDEP | |
1334 | struct held_lock *hlock, *prev_hlock = NULL; | |
1335 | unsigned int i, id; | |
1336 | u64 chain_key = 0; | |
1337 | ||
1338 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1339 | hlock = curr->held_locks + i; | |
1340 | if (chain_key != hlock->prev_chain_key) { | |
1341 | debug_locks_off(); | |
1342 | printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n", | |
1343 | curr->lockdep_depth, i, | |
1344 | (unsigned long long)chain_key, | |
1345 | (unsigned long long)hlock->prev_chain_key); | |
1346 | WARN_ON(1); | |
1347 | return; | |
1348 | } | |
1349 | id = hlock->class - lock_classes; | |
1350 | DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS); | |
1351 | if (prev_hlock && (prev_hlock->irq_context != | |
1352 | hlock->irq_context)) | |
1353 | chain_key = 0; | |
1354 | chain_key = iterate_chain_key(chain_key, id); | |
1355 | prev_hlock = hlock; | |
1356 | } | |
1357 | if (chain_key != curr->curr_chain_key) { | |
1358 | debug_locks_off(); | |
1359 | printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n", | |
1360 | curr->lockdep_depth, i, | |
1361 | (unsigned long long)chain_key, | |
1362 | (unsigned long long)curr->curr_chain_key); | |
1363 | WARN_ON(1); | |
1364 | } | |
1365 | #endif | |
1366 | } | |
1367 | ||
1368 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1369 | ||
1370 | /* | |
1371 | * print irq inversion bug: | |
1372 | */ | |
1373 | static int | |
1374 | print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other, | |
1375 | struct held_lock *this, int forwards, | |
1376 | const char *irqclass) | |
1377 | { | |
1378 | __raw_spin_unlock(&hash_lock); | |
1379 | debug_locks_off(); | |
1380 | if (debug_locks_silent) | |
1381 | return 0; | |
1382 | ||
1383 | printk("\n=========================================================\n"); | |
1384 | printk( "[ INFO: possible irq lock inversion dependency detected ]\n"); | |
99de055a | 1385 | print_kernel_version(); |
fbb9ce95 IM |
1386 | printk( "---------------------------------------------------------\n"); |
1387 | printk("%s/%d just changed the state of lock:\n", | |
1388 | curr->comm, curr->pid); | |
1389 | print_lock(this); | |
1390 | if (forwards) | |
1391 | printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass); | |
1392 | else | |
1393 | printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass); | |
1394 | print_lock_name(other); | |
1395 | printk("\n\nand interrupts could create inverse lock ordering between them.\n\n"); | |
1396 | ||
1397 | printk("\nother info that might help us debug this:\n"); | |
1398 | lockdep_print_held_locks(curr); | |
1399 | ||
1400 | printk("\nthe first lock's dependencies:\n"); | |
1401 | print_lock_dependencies(this->class, 0); | |
1402 | ||
1403 | printk("\nthe second lock's dependencies:\n"); | |
1404 | print_lock_dependencies(other, 0); | |
1405 | ||
1406 | printk("\nstack backtrace:\n"); | |
1407 | dump_stack(); | |
1408 | ||
1409 | return 0; | |
1410 | } | |
1411 | ||
1412 | /* | |
1413 | * Prove that in the forwards-direction subgraph starting at <this> | |
1414 | * there is no lock matching <mask>: | |
1415 | */ | |
1416 | static int | |
1417 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, | |
1418 | enum lock_usage_bit bit, const char *irqclass) | |
1419 | { | |
1420 | int ret; | |
1421 | ||
1422 | find_usage_bit = bit; | |
1423 | /* fills in <forwards_match> */ | |
1424 | ret = find_usage_forwards(this->class, 0); | |
1425 | if (!ret || ret == 1) | |
1426 | return ret; | |
1427 | ||
1428 | return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass); | |
1429 | } | |
1430 | ||
1431 | /* | |
1432 | * Prove that in the backwards-direction subgraph starting at <this> | |
1433 | * there is no lock matching <mask>: | |
1434 | */ | |
1435 | static int | |
1436 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, | |
1437 | enum lock_usage_bit bit, const char *irqclass) | |
1438 | { | |
1439 | int ret; | |
1440 | ||
1441 | find_usage_bit = bit; | |
1442 | /* fills in <backwards_match> */ | |
1443 | ret = find_usage_backwards(this->class, 0); | |
1444 | if (!ret || ret == 1) | |
1445 | return ret; | |
1446 | ||
1447 | return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass); | |
1448 | } | |
1449 | ||
3117df04 | 1450 | void print_irqtrace_events(struct task_struct *curr) |
fbb9ce95 IM |
1451 | { |
1452 | printk("irq event stamp: %u\n", curr->irq_events); | |
1453 | printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event); | |
1454 | print_ip_sym(curr->hardirq_enable_ip); | |
1455 | printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event); | |
1456 | print_ip_sym(curr->hardirq_disable_ip); | |
1457 | printk("softirqs last enabled at (%u): ", curr->softirq_enable_event); | |
1458 | print_ip_sym(curr->softirq_enable_ip); | |
1459 | printk("softirqs last disabled at (%u): ", curr->softirq_disable_event); | |
1460 | print_ip_sym(curr->softirq_disable_ip); | |
1461 | } | |
1462 | ||
fbb9ce95 IM |
1463 | #endif |
1464 | ||
1465 | static int | |
1466 | print_usage_bug(struct task_struct *curr, struct held_lock *this, | |
1467 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) | |
1468 | { | |
1469 | __raw_spin_unlock(&hash_lock); | |
1470 | debug_locks_off(); | |
1471 | if (debug_locks_silent) | |
1472 | return 0; | |
1473 | ||
1474 | printk("\n=================================\n"); | |
1475 | printk( "[ INFO: inconsistent lock state ]\n"); | |
99de055a | 1476 | print_kernel_version(); |
fbb9ce95 IM |
1477 | printk( "---------------------------------\n"); |
1478 | ||
1479 | printk("inconsistent {%s} -> {%s} usage.\n", | |
1480 | usage_str[prev_bit], usage_str[new_bit]); | |
1481 | ||
1482 | printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", | |
1483 | curr->comm, curr->pid, | |
1484 | trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, | |
1485 | trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, | |
1486 | trace_hardirqs_enabled(curr), | |
1487 | trace_softirqs_enabled(curr)); | |
1488 | print_lock(this); | |
1489 | ||
1490 | printk("{%s} state was registered at:\n", usage_str[prev_bit]); | |
1491 | print_stack_trace(this->class->usage_traces + prev_bit, 1); | |
1492 | ||
1493 | print_irqtrace_events(curr); | |
1494 | printk("\nother info that might help us debug this:\n"); | |
1495 | lockdep_print_held_locks(curr); | |
1496 | ||
1497 | printk("\nstack backtrace:\n"); | |
1498 | dump_stack(); | |
1499 | ||
1500 | return 0; | |
1501 | } | |
1502 | ||
1503 | /* | |
1504 | * Print out an error if an invalid bit is set: | |
1505 | */ | |
1506 | static inline int | |
1507 | valid_state(struct task_struct *curr, struct held_lock *this, | |
1508 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) | |
1509 | { | |
1510 | if (unlikely(this->class->usage_mask & (1 << bad_bit))) | |
1511 | return print_usage_bug(curr, this, bad_bit, new_bit); | |
1512 | return 1; | |
1513 | } | |
1514 | ||
1515 | #define STRICT_READ_CHECKS 1 | |
1516 | ||
1517 | /* | |
1518 | * Mark a lock with a usage bit, and validate the state transition: | |
1519 | */ | |
1520 | static int mark_lock(struct task_struct *curr, struct held_lock *this, | |
1521 | enum lock_usage_bit new_bit, unsigned long ip) | |
1522 | { | |
1523 | unsigned int new_mask = 1 << new_bit, ret = 1; | |
1524 | ||
1525 | /* | |
1526 | * If already set then do not dirty the cacheline, | |
1527 | * nor do any checks: | |
1528 | */ | |
1529 | if (likely(this->class->usage_mask & new_mask)) | |
1530 | return 1; | |
1531 | ||
1532 | __raw_spin_lock(&hash_lock); | |
1533 | /* | |
1534 | * Make sure we didnt race: | |
1535 | */ | |
1536 | if (unlikely(this->class->usage_mask & new_mask)) { | |
1537 | __raw_spin_unlock(&hash_lock); | |
1538 | return 1; | |
1539 | } | |
1540 | ||
1541 | this->class->usage_mask |= new_mask; | |
1542 | ||
1543 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1544 | if (new_bit == LOCK_ENABLED_HARDIRQS || | |
1545 | new_bit == LOCK_ENABLED_HARDIRQS_READ) | |
1546 | ip = curr->hardirq_enable_ip; | |
1547 | else if (new_bit == LOCK_ENABLED_SOFTIRQS || | |
1548 | new_bit == LOCK_ENABLED_SOFTIRQS_READ) | |
1549 | ip = curr->softirq_enable_ip; | |
1550 | #endif | |
1551 | if (!save_trace(this->class->usage_traces + new_bit)) | |
1552 | return 0; | |
1553 | ||
1554 | switch (new_bit) { | |
1555 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1556 | case LOCK_USED_IN_HARDIRQ: | |
1557 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1558 | return 0; | |
1559 | if (!valid_state(curr, this, new_bit, | |
1560 | LOCK_ENABLED_HARDIRQS_READ)) | |
1561 | return 0; | |
1562 | /* | |
1563 | * just marked it hardirq-safe, check that this lock | |
1564 | * took no hardirq-unsafe lock in the past: | |
1565 | */ | |
1566 | if (!check_usage_forwards(curr, this, | |
1567 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1568 | return 0; | |
1569 | #if STRICT_READ_CHECKS | |
1570 | /* | |
1571 | * just marked it hardirq-safe, check that this lock | |
1572 | * took no hardirq-unsafe-read lock in the past: | |
1573 | */ | |
1574 | if (!check_usage_forwards(curr, this, | |
1575 | LOCK_ENABLED_HARDIRQS_READ, "hard-read")) | |
1576 | return 0; | |
1577 | #endif | |
1578 | if (hardirq_verbose(this->class)) | |
1579 | ret = 2; | |
1580 | break; | |
1581 | case LOCK_USED_IN_SOFTIRQ: | |
1582 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1583 | return 0; | |
1584 | if (!valid_state(curr, this, new_bit, | |
1585 | LOCK_ENABLED_SOFTIRQS_READ)) | |
1586 | return 0; | |
1587 | /* | |
1588 | * just marked it softirq-safe, check that this lock | |
1589 | * took no softirq-unsafe lock in the past: | |
1590 | */ | |
1591 | if (!check_usage_forwards(curr, this, | |
1592 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1593 | return 0; | |
1594 | #if STRICT_READ_CHECKS | |
1595 | /* | |
1596 | * just marked it softirq-safe, check that this lock | |
1597 | * took no softirq-unsafe-read lock in the past: | |
1598 | */ | |
1599 | if (!check_usage_forwards(curr, this, | |
1600 | LOCK_ENABLED_SOFTIRQS_READ, "soft-read")) | |
1601 | return 0; | |
1602 | #endif | |
1603 | if (softirq_verbose(this->class)) | |
1604 | ret = 2; | |
1605 | break; | |
1606 | case LOCK_USED_IN_HARDIRQ_READ: | |
1607 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS)) | |
1608 | return 0; | |
1609 | /* | |
1610 | * just marked it hardirq-read-safe, check that this lock | |
1611 | * took no hardirq-unsafe lock in the past: | |
1612 | */ | |
1613 | if (!check_usage_forwards(curr, this, | |
1614 | LOCK_ENABLED_HARDIRQS, "hard")) | |
1615 | return 0; | |
1616 | if (hardirq_verbose(this->class)) | |
1617 | ret = 2; | |
1618 | break; | |
1619 | case LOCK_USED_IN_SOFTIRQ_READ: | |
1620 | if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS)) | |
1621 | return 0; | |
1622 | /* | |
1623 | * just marked it softirq-read-safe, check that this lock | |
1624 | * took no softirq-unsafe lock in the past: | |
1625 | */ | |
1626 | if (!check_usage_forwards(curr, this, | |
1627 | LOCK_ENABLED_SOFTIRQS, "soft")) | |
1628 | return 0; | |
1629 | if (softirq_verbose(this->class)) | |
1630 | ret = 2; | |
1631 | break; | |
1632 | case LOCK_ENABLED_HARDIRQS: | |
1633 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1634 | return 0; | |
1635 | if (!valid_state(curr, this, new_bit, | |
1636 | LOCK_USED_IN_HARDIRQ_READ)) | |
1637 | return 0; | |
1638 | /* | |
1639 | * just marked it hardirq-unsafe, check that no hardirq-safe | |
1640 | * lock in the system ever took it in the past: | |
1641 | */ | |
1642 | if (!check_usage_backwards(curr, this, | |
1643 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1644 | return 0; | |
1645 | #if STRICT_READ_CHECKS | |
1646 | /* | |
1647 | * just marked it hardirq-unsafe, check that no | |
1648 | * hardirq-safe-read lock in the system ever took | |
1649 | * it in the past: | |
1650 | */ | |
1651 | if (!check_usage_backwards(curr, this, | |
1652 | LOCK_USED_IN_HARDIRQ_READ, "hard-read")) | |
1653 | return 0; | |
1654 | #endif | |
1655 | if (hardirq_verbose(this->class)) | |
1656 | ret = 2; | |
1657 | break; | |
1658 | case LOCK_ENABLED_SOFTIRQS: | |
1659 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1660 | return 0; | |
1661 | if (!valid_state(curr, this, new_bit, | |
1662 | LOCK_USED_IN_SOFTIRQ_READ)) | |
1663 | return 0; | |
1664 | /* | |
1665 | * just marked it softirq-unsafe, check that no softirq-safe | |
1666 | * lock in the system ever took it in the past: | |
1667 | */ | |
1668 | if (!check_usage_backwards(curr, this, | |
1669 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1670 | return 0; | |
1671 | #if STRICT_READ_CHECKS | |
1672 | /* | |
1673 | * just marked it softirq-unsafe, check that no | |
1674 | * softirq-safe-read lock in the system ever took | |
1675 | * it in the past: | |
1676 | */ | |
1677 | if (!check_usage_backwards(curr, this, | |
1678 | LOCK_USED_IN_SOFTIRQ_READ, "soft-read")) | |
1679 | return 0; | |
1680 | #endif | |
1681 | if (softirq_verbose(this->class)) | |
1682 | ret = 2; | |
1683 | break; | |
1684 | case LOCK_ENABLED_HARDIRQS_READ: | |
1685 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ)) | |
1686 | return 0; | |
1687 | #if STRICT_READ_CHECKS | |
1688 | /* | |
1689 | * just marked it hardirq-read-unsafe, check that no | |
1690 | * hardirq-safe lock in the system ever took it in the past: | |
1691 | */ | |
1692 | if (!check_usage_backwards(curr, this, | |
1693 | LOCK_USED_IN_HARDIRQ, "hard")) | |
1694 | return 0; | |
1695 | #endif | |
1696 | if (hardirq_verbose(this->class)) | |
1697 | ret = 2; | |
1698 | break; | |
1699 | case LOCK_ENABLED_SOFTIRQS_READ: | |
1700 | if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ)) | |
1701 | return 0; | |
1702 | #if STRICT_READ_CHECKS | |
1703 | /* | |
1704 | * just marked it softirq-read-unsafe, check that no | |
1705 | * softirq-safe lock in the system ever took it in the past: | |
1706 | */ | |
1707 | if (!check_usage_backwards(curr, this, | |
1708 | LOCK_USED_IN_SOFTIRQ, "soft")) | |
1709 | return 0; | |
1710 | #endif | |
1711 | if (softirq_verbose(this->class)) | |
1712 | ret = 2; | |
1713 | break; | |
1714 | #endif | |
1715 | case LOCK_USED: | |
1716 | /* | |
1717 | * Add it to the global list of classes: | |
1718 | */ | |
1719 | list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes); | |
1720 | debug_atomic_dec(&nr_unused_locks); | |
1721 | break; | |
1722 | default: | |
b23984d0 | 1723 | __raw_spin_unlock(&hash_lock); |
fbb9ce95 IM |
1724 | debug_locks_off(); |
1725 | WARN_ON(1); | |
1726 | return 0; | |
1727 | } | |
1728 | ||
1729 | __raw_spin_unlock(&hash_lock); | |
1730 | ||
1731 | /* | |
1732 | * We must printk outside of the hash_lock: | |
1733 | */ | |
1734 | if (ret == 2) { | |
1735 | printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); | |
1736 | print_lock(this); | |
1737 | print_irqtrace_events(curr); | |
1738 | dump_stack(); | |
1739 | } | |
1740 | ||
1741 | return ret; | |
1742 | } | |
1743 | ||
1744 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1745 | /* | |
1746 | * Mark all held locks with a usage bit: | |
1747 | */ | |
1748 | static int | |
1749 | mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip) | |
1750 | { | |
1751 | enum lock_usage_bit usage_bit; | |
1752 | struct held_lock *hlock; | |
1753 | int i; | |
1754 | ||
1755 | for (i = 0; i < curr->lockdep_depth; i++) { | |
1756 | hlock = curr->held_locks + i; | |
1757 | ||
1758 | if (hardirq) { | |
1759 | if (hlock->read) | |
1760 | usage_bit = LOCK_ENABLED_HARDIRQS_READ; | |
1761 | else | |
1762 | usage_bit = LOCK_ENABLED_HARDIRQS; | |
1763 | } else { | |
1764 | if (hlock->read) | |
1765 | usage_bit = LOCK_ENABLED_SOFTIRQS_READ; | |
1766 | else | |
1767 | usage_bit = LOCK_ENABLED_SOFTIRQS; | |
1768 | } | |
1769 | if (!mark_lock(curr, hlock, usage_bit, ip)) | |
1770 | return 0; | |
1771 | } | |
1772 | ||
1773 | return 1; | |
1774 | } | |
1775 | ||
1776 | /* | |
1777 | * Debugging helper: via this flag we know that we are in | |
1778 | * 'early bootup code', and will warn about any invalid irqs-on event: | |
1779 | */ | |
1780 | static int early_boot_irqs_enabled; | |
1781 | ||
1782 | void early_boot_irqs_off(void) | |
1783 | { | |
1784 | early_boot_irqs_enabled = 0; | |
1785 | } | |
1786 | ||
1787 | void early_boot_irqs_on(void) | |
1788 | { | |
1789 | early_boot_irqs_enabled = 1; | |
1790 | } | |
1791 | ||
1792 | /* | |
1793 | * Hardirqs will be enabled: | |
1794 | */ | |
1795 | void trace_hardirqs_on(void) | |
1796 | { | |
1797 | struct task_struct *curr = current; | |
1798 | unsigned long ip; | |
1799 | ||
1800 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1801 | return; | |
1802 | ||
1803 | if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) | |
1804 | return; | |
1805 | ||
1806 | if (unlikely(curr->hardirqs_enabled)) { | |
1807 | debug_atomic_inc(&redundant_hardirqs_on); | |
1808 | return; | |
1809 | } | |
1810 | /* we'll do an OFF -> ON transition: */ | |
1811 | curr->hardirqs_enabled = 1; | |
1812 | ip = (unsigned long) __builtin_return_address(0); | |
1813 | ||
1814 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1815 | return; | |
1816 | if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) | |
1817 | return; | |
1818 | /* | |
1819 | * We are going to turn hardirqs on, so set the | |
1820 | * usage bit for all held locks: | |
1821 | */ | |
1822 | if (!mark_held_locks(curr, 1, ip)) | |
1823 | return; | |
1824 | /* | |
1825 | * If we have softirqs enabled, then set the usage | |
1826 | * bit for all held locks. (disabled hardirqs prevented | |
1827 | * this bit from being set before) | |
1828 | */ | |
1829 | if (curr->softirqs_enabled) | |
1830 | if (!mark_held_locks(curr, 0, ip)) | |
1831 | return; | |
1832 | ||
1833 | curr->hardirq_enable_ip = ip; | |
1834 | curr->hardirq_enable_event = ++curr->irq_events; | |
1835 | debug_atomic_inc(&hardirqs_on_events); | |
1836 | } | |
1837 | ||
1838 | EXPORT_SYMBOL(trace_hardirqs_on); | |
1839 | ||
1840 | /* | |
1841 | * Hardirqs were disabled: | |
1842 | */ | |
1843 | void trace_hardirqs_off(void) | |
1844 | { | |
1845 | struct task_struct *curr = current; | |
1846 | ||
1847 | if (unlikely(!debug_locks || current->lockdep_recursion)) | |
1848 | return; | |
1849 | ||
1850 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1851 | return; | |
1852 | ||
1853 | if (curr->hardirqs_enabled) { | |
1854 | /* | |
1855 | * We have done an ON -> OFF transition: | |
1856 | */ | |
1857 | curr->hardirqs_enabled = 0; | |
1858 | curr->hardirq_disable_ip = _RET_IP_; | |
1859 | curr->hardirq_disable_event = ++curr->irq_events; | |
1860 | debug_atomic_inc(&hardirqs_off_events); | |
1861 | } else | |
1862 | debug_atomic_inc(&redundant_hardirqs_off); | |
1863 | } | |
1864 | ||
1865 | EXPORT_SYMBOL(trace_hardirqs_off); | |
1866 | ||
1867 | /* | |
1868 | * Softirqs will be enabled: | |
1869 | */ | |
1870 | void trace_softirqs_on(unsigned long ip) | |
1871 | { | |
1872 | struct task_struct *curr = current; | |
1873 | ||
1874 | if (unlikely(!debug_locks)) | |
1875 | return; | |
1876 | ||
1877 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1878 | return; | |
1879 | ||
1880 | if (curr->softirqs_enabled) { | |
1881 | debug_atomic_inc(&redundant_softirqs_on); | |
1882 | return; | |
1883 | } | |
1884 | ||
1885 | /* | |
1886 | * We'll do an OFF -> ON transition: | |
1887 | */ | |
1888 | curr->softirqs_enabled = 1; | |
1889 | curr->softirq_enable_ip = ip; | |
1890 | curr->softirq_enable_event = ++curr->irq_events; | |
1891 | debug_atomic_inc(&softirqs_on_events); | |
1892 | /* | |
1893 | * We are going to turn softirqs on, so set the | |
1894 | * usage bit for all held locks, if hardirqs are | |
1895 | * enabled too: | |
1896 | */ | |
1897 | if (curr->hardirqs_enabled) | |
1898 | mark_held_locks(curr, 0, ip); | |
1899 | } | |
1900 | ||
1901 | /* | |
1902 | * Softirqs were disabled: | |
1903 | */ | |
1904 | void trace_softirqs_off(unsigned long ip) | |
1905 | { | |
1906 | struct task_struct *curr = current; | |
1907 | ||
1908 | if (unlikely(!debug_locks)) | |
1909 | return; | |
1910 | ||
1911 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1912 | return; | |
1913 | ||
1914 | if (curr->softirqs_enabled) { | |
1915 | /* | |
1916 | * We have done an ON -> OFF transition: | |
1917 | */ | |
1918 | curr->softirqs_enabled = 0; | |
1919 | curr->softirq_disable_ip = ip; | |
1920 | curr->softirq_disable_event = ++curr->irq_events; | |
1921 | debug_atomic_inc(&softirqs_off_events); | |
1922 | DEBUG_LOCKS_WARN_ON(!softirq_count()); | |
1923 | } else | |
1924 | debug_atomic_inc(&redundant_softirqs_off); | |
1925 | } | |
1926 | ||
1927 | #endif | |
1928 | ||
1929 | /* | |
1930 | * Initialize a lock instance's lock-class mapping info: | |
1931 | */ | |
1932 | void lockdep_init_map(struct lockdep_map *lock, const char *name, | |
4dfbb9d8 | 1933 | struct lock_class_key *key, int subclass) |
fbb9ce95 IM |
1934 | { |
1935 | if (unlikely(!debug_locks)) | |
1936 | return; | |
1937 | ||
1938 | if (DEBUG_LOCKS_WARN_ON(!key)) | |
1939 | return; | |
1940 | if (DEBUG_LOCKS_WARN_ON(!name)) | |
1941 | return; | |
1942 | /* | |
1943 | * Sanity check, the lock-class key must be persistent: | |
1944 | */ | |
1945 | if (!static_obj(key)) { | |
1946 | printk("BUG: key %p not in .data!\n", key); | |
1947 | DEBUG_LOCKS_WARN_ON(1); | |
1948 | return; | |
1949 | } | |
1950 | lock->name = name; | |
1951 | lock->key = key; | |
d6d897ce | 1952 | lock->class_cache = NULL; |
4dfbb9d8 PZ |
1953 | if (subclass) |
1954 | register_lock_class(lock, subclass, 1); | |
fbb9ce95 IM |
1955 | } |
1956 | ||
1957 | EXPORT_SYMBOL_GPL(lockdep_init_map); | |
1958 | ||
1959 | /* | |
1960 | * This gets called for every mutex_lock*()/spin_lock*() operation. | |
1961 | * We maintain the dependency maps and validate the locking attempt: | |
1962 | */ | |
1963 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
1964 | int trylock, int read, int check, int hardirqs_off, | |
1965 | unsigned long ip) | |
1966 | { | |
1967 | struct task_struct *curr = current; | |
d6d897ce | 1968 | struct lock_class *class = NULL; |
fbb9ce95 | 1969 | struct held_lock *hlock; |
fbb9ce95 IM |
1970 | unsigned int depth, id; |
1971 | int chain_head = 0; | |
1972 | u64 chain_key; | |
1973 | ||
1974 | if (unlikely(!debug_locks)) | |
1975 | return 0; | |
1976 | ||
1977 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
1978 | return 0; | |
1979 | ||
1980 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { | |
1981 | debug_locks_off(); | |
1982 | printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n"); | |
1983 | printk("turning off the locking correctness validator.\n"); | |
1984 | return 0; | |
1985 | } | |
1986 | ||
d6d897ce IM |
1987 | if (!subclass) |
1988 | class = lock->class_cache; | |
1989 | /* | |
1990 | * Not cached yet or subclass? | |
1991 | */ | |
fbb9ce95 | 1992 | if (unlikely(!class)) { |
4dfbb9d8 | 1993 | class = register_lock_class(lock, subclass, 0); |
fbb9ce95 IM |
1994 | if (!class) |
1995 | return 0; | |
1996 | } | |
1997 | debug_atomic_inc((atomic_t *)&class->ops); | |
1998 | if (very_verbose(class)) { | |
1999 | printk("\nacquire class [%p] %s", class->key, class->name); | |
2000 | if (class->name_version > 1) | |
2001 | printk("#%d", class->name_version); | |
2002 | printk("\n"); | |
2003 | dump_stack(); | |
2004 | } | |
2005 | ||
2006 | /* | |
2007 | * Add the lock to the list of currently held locks. | |
2008 | * (we dont increase the depth just yet, up until the | |
2009 | * dependency checks are done) | |
2010 | */ | |
2011 | depth = curr->lockdep_depth; | |
2012 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) | |
2013 | return 0; | |
2014 | ||
2015 | hlock = curr->held_locks + depth; | |
2016 | ||
2017 | hlock->class = class; | |
2018 | hlock->acquire_ip = ip; | |
2019 | hlock->instance = lock; | |
2020 | hlock->trylock = trylock; | |
2021 | hlock->read = read; | |
2022 | hlock->check = check; | |
2023 | hlock->hardirqs_off = hardirqs_off; | |
2024 | ||
2025 | if (check != 2) | |
2026 | goto out_calc_hash; | |
2027 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2028 | /* | |
2029 | * If non-trylock use in a hardirq or softirq context, then | |
2030 | * mark the lock as used in these contexts: | |
2031 | */ | |
2032 | if (!trylock) { | |
2033 | if (read) { | |
2034 | if (curr->hardirq_context) | |
2035 | if (!mark_lock(curr, hlock, | |
2036 | LOCK_USED_IN_HARDIRQ_READ, ip)) | |
2037 | return 0; | |
2038 | if (curr->softirq_context) | |
2039 | if (!mark_lock(curr, hlock, | |
2040 | LOCK_USED_IN_SOFTIRQ_READ, ip)) | |
2041 | return 0; | |
2042 | } else { | |
2043 | if (curr->hardirq_context) | |
2044 | if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip)) | |
2045 | return 0; | |
2046 | if (curr->softirq_context) | |
2047 | if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip)) | |
2048 | return 0; | |
2049 | } | |
2050 | } | |
2051 | if (!hardirqs_off) { | |
2052 | if (read) { | |
2053 | if (!mark_lock(curr, hlock, | |
2054 | LOCK_ENABLED_HARDIRQS_READ, ip)) | |
2055 | return 0; | |
2056 | if (curr->softirqs_enabled) | |
2057 | if (!mark_lock(curr, hlock, | |
2058 | LOCK_ENABLED_SOFTIRQS_READ, ip)) | |
2059 | return 0; | |
2060 | } else { | |
2061 | if (!mark_lock(curr, hlock, | |
2062 | LOCK_ENABLED_HARDIRQS, ip)) | |
2063 | return 0; | |
2064 | if (curr->softirqs_enabled) | |
2065 | if (!mark_lock(curr, hlock, | |
2066 | LOCK_ENABLED_SOFTIRQS, ip)) | |
2067 | return 0; | |
2068 | } | |
2069 | } | |
2070 | #endif | |
2071 | /* mark it as used: */ | |
2072 | if (!mark_lock(curr, hlock, LOCK_USED, ip)) | |
2073 | return 0; | |
2074 | out_calc_hash: | |
2075 | /* | |
2076 | * Calculate the chain hash: it's the combined has of all the | |
2077 | * lock keys along the dependency chain. We save the hash value | |
2078 | * at every step so that we can get the current hash easily | |
2079 | * after unlock. The chain hash is then used to cache dependency | |
2080 | * results. | |
2081 | * | |
2082 | * The 'key ID' is what is the most compact key value to drive | |
2083 | * the hash, not class->key. | |
2084 | */ | |
2085 | id = class - lock_classes; | |
2086 | if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) | |
2087 | return 0; | |
2088 | ||
2089 | chain_key = curr->curr_chain_key; | |
2090 | if (!depth) { | |
2091 | if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) | |
2092 | return 0; | |
2093 | chain_head = 1; | |
2094 | } | |
2095 | ||
2096 | hlock->prev_chain_key = chain_key; | |
2097 | ||
2098 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2099 | /* | |
2100 | * Keep track of points where we cross into an interrupt context: | |
2101 | */ | |
2102 | hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) + | |
2103 | curr->softirq_context; | |
2104 | if (depth) { | |
2105 | struct held_lock *prev_hlock; | |
2106 | ||
2107 | prev_hlock = curr->held_locks + depth-1; | |
2108 | /* | |
2109 | * If we cross into another context, reset the | |
2110 | * hash key (this also prevents the checking and the | |
2111 | * adding of the dependency to 'prev'): | |
2112 | */ | |
2113 | if (prev_hlock->irq_context != hlock->irq_context) { | |
2114 | chain_key = 0; | |
2115 | chain_head = 1; | |
2116 | } | |
2117 | } | |
2118 | #endif | |
2119 | chain_key = iterate_chain_key(chain_key, id); | |
2120 | curr->curr_chain_key = chain_key; | |
2121 | ||
2122 | /* | |
2123 | * Trylock needs to maintain the stack of held locks, but it | |
2124 | * does not add new dependencies, because trylock can be done | |
2125 | * in any order. | |
2126 | * | |
2127 | * We look up the chain_key and do the O(N^2) check and update of | |
2128 | * the dependencies only if this is a new dependency chain. | |
2129 | * (If lookup_chain_cache() returns with 1 it acquires | |
2130 | * hash_lock for us) | |
2131 | */ | |
81fc685a | 2132 | if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) { |
fbb9ce95 IM |
2133 | /* |
2134 | * Check whether last held lock: | |
2135 | * | |
2136 | * - is irq-safe, if this lock is irq-unsafe | |
2137 | * - is softirq-safe, if this lock is hardirq-unsafe | |
2138 | * | |
2139 | * And check whether the new lock's dependency graph | |
2140 | * could lead back to the previous lock. | |
2141 | * | |
2142 | * any of these scenarios could lead to a deadlock. If | |
2143 | * All validations | |
2144 | */ | |
2145 | int ret = check_deadlock(curr, hlock, lock, read); | |
2146 | ||
2147 | if (!ret) | |
2148 | return 0; | |
2149 | /* | |
2150 | * Mark recursive read, as we jump over it when | |
2151 | * building dependencies (just like we jump over | |
2152 | * trylock entries): | |
2153 | */ | |
2154 | if (ret == 2) | |
2155 | hlock->read = 2; | |
2156 | /* | |
2157 | * Add dependency only if this lock is not the head | |
2158 | * of the chain, and if it's not a secondary read-lock: | |
2159 | */ | |
2160 | if (!chain_head && ret != 2) | |
2161 | if (!check_prevs_add(curr, hlock)) | |
2162 | return 0; | |
2163 | __raw_spin_unlock(&hash_lock); | |
2164 | } | |
2165 | curr->lockdep_depth++; | |
2166 | check_chain_key(curr); | |
2167 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { | |
2168 | debug_locks_off(); | |
2169 | printk("BUG: MAX_LOCK_DEPTH too low!\n"); | |
2170 | printk("turning off the locking correctness validator.\n"); | |
2171 | return 0; | |
2172 | } | |
2173 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) | |
2174 | max_lockdep_depth = curr->lockdep_depth; | |
2175 | ||
2176 | return 1; | |
2177 | } | |
2178 | ||
2179 | static int | |
2180 | print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock, | |
2181 | unsigned long ip) | |
2182 | { | |
2183 | if (!debug_locks_off()) | |
2184 | return 0; | |
2185 | if (debug_locks_silent) | |
2186 | return 0; | |
2187 | ||
2188 | printk("\n=====================================\n"); | |
2189 | printk( "[ BUG: bad unlock balance detected! ]\n"); | |
2190 | printk( "-------------------------------------\n"); | |
2191 | printk("%s/%d is trying to release lock (", | |
2192 | curr->comm, curr->pid); | |
2193 | print_lockdep_cache(lock); | |
2194 | printk(") at:\n"); | |
2195 | print_ip_sym(ip); | |
2196 | printk("but there are no more locks to release!\n"); | |
2197 | printk("\nother info that might help us debug this:\n"); | |
2198 | lockdep_print_held_locks(curr); | |
2199 | ||
2200 | printk("\nstack backtrace:\n"); | |
2201 | dump_stack(); | |
2202 | ||
2203 | return 0; | |
2204 | } | |
2205 | ||
2206 | /* | |
2207 | * Common debugging checks for both nested and non-nested unlock: | |
2208 | */ | |
2209 | static int check_unlock(struct task_struct *curr, struct lockdep_map *lock, | |
2210 | unsigned long ip) | |
2211 | { | |
2212 | if (unlikely(!debug_locks)) | |
2213 | return 0; | |
2214 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) | |
2215 | return 0; | |
2216 | ||
2217 | if (curr->lockdep_depth <= 0) | |
2218 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2219 | ||
2220 | return 1; | |
2221 | } | |
2222 | ||
2223 | /* | |
2224 | * Remove the lock to the list of currently held locks in a | |
2225 | * potentially non-nested (out of order) manner. This is a | |
2226 | * relatively rare operation, as all the unlock APIs default | |
2227 | * to nested mode (which uses lock_release()): | |
2228 | */ | |
2229 | static int | |
2230 | lock_release_non_nested(struct task_struct *curr, | |
2231 | struct lockdep_map *lock, unsigned long ip) | |
2232 | { | |
2233 | struct held_lock *hlock, *prev_hlock; | |
2234 | unsigned int depth; | |
2235 | int i; | |
2236 | ||
2237 | /* | |
2238 | * Check whether the lock exists in the current stack | |
2239 | * of held locks: | |
2240 | */ | |
2241 | depth = curr->lockdep_depth; | |
2242 | if (DEBUG_LOCKS_WARN_ON(!depth)) | |
2243 | return 0; | |
2244 | ||
2245 | prev_hlock = NULL; | |
2246 | for (i = depth-1; i >= 0; i--) { | |
2247 | hlock = curr->held_locks + i; | |
2248 | /* | |
2249 | * We must not cross into another context: | |
2250 | */ | |
2251 | if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) | |
2252 | break; | |
2253 | if (hlock->instance == lock) | |
2254 | goto found_it; | |
2255 | prev_hlock = hlock; | |
2256 | } | |
2257 | return print_unlock_inbalance_bug(curr, lock, ip); | |
2258 | ||
2259 | found_it: | |
2260 | /* | |
2261 | * We have the right lock to unlock, 'hlock' points to it. | |
2262 | * Now we remove it from the stack, and add back the other | |
2263 | * entries (if any), recalculating the hash along the way: | |
2264 | */ | |
2265 | curr->lockdep_depth = i; | |
2266 | curr->curr_chain_key = hlock->prev_chain_key; | |
2267 | ||
2268 | for (i++; i < depth; i++) { | |
2269 | hlock = curr->held_locks + i; | |
2270 | if (!__lock_acquire(hlock->instance, | |
2271 | hlock->class->subclass, hlock->trylock, | |
2272 | hlock->read, hlock->check, hlock->hardirqs_off, | |
2273 | hlock->acquire_ip)) | |
2274 | return 0; | |
2275 | } | |
2276 | ||
2277 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1)) | |
2278 | return 0; | |
2279 | return 1; | |
2280 | } | |
2281 | ||
2282 | /* | |
2283 | * Remove the lock to the list of currently held locks - this gets | |
2284 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2285 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2286 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2287 | */ | |
2288 | static int lock_release_nested(struct task_struct *curr, | |
2289 | struct lockdep_map *lock, unsigned long ip) | |
2290 | { | |
2291 | struct held_lock *hlock; | |
2292 | unsigned int depth; | |
2293 | ||
2294 | /* | |
2295 | * Pop off the top of the lock stack: | |
2296 | */ | |
2297 | depth = curr->lockdep_depth - 1; | |
2298 | hlock = curr->held_locks + depth; | |
2299 | ||
2300 | /* | |
2301 | * Is the unlock non-nested: | |
2302 | */ | |
2303 | if (hlock->instance != lock) | |
2304 | return lock_release_non_nested(curr, lock, ip); | |
2305 | curr->lockdep_depth--; | |
2306 | ||
2307 | if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0))) | |
2308 | return 0; | |
2309 | ||
2310 | curr->curr_chain_key = hlock->prev_chain_key; | |
2311 | ||
2312 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2313 | hlock->prev_chain_key = 0; | |
2314 | hlock->class = NULL; | |
2315 | hlock->acquire_ip = 0; | |
2316 | hlock->irq_context = 0; | |
2317 | #endif | |
2318 | return 1; | |
2319 | } | |
2320 | ||
2321 | /* | |
2322 | * Remove the lock to the list of currently held locks - this gets | |
2323 | * called on mutex_unlock()/spin_unlock*() (or on a failed | |
2324 | * mutex_lock_interruptible()). This is done for unlocks that nest | |
2325 | * perfectly. (i.e. the current top of the lock-stack is unlocked) | |
2326 | */ | |
2327 | static void | |
2328 | __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2329 | { | |
2330 | struct task_struct *curr = current; | |
2331 | ||
2332 | if (!check_unlock(curr, lock, ip)) | |
2333 | return; | |
2334 | ||
2335 | if (nested) { | |
2336 | if (!lock_release_nested(curr, lock, ip)) | |
2337 | return; | |
2338 | } else { | |
2339 | if (!lock_release_non_nested(curr, lock, ip)) | |
2340 | return; | |
2341 | } | |
2342 | ||
2343 | check_chain_key(curr); | |
2344 | } | |
2345 | ||
2346 | /* | |
2347 | * Check whether we follow the irq-flags state precisely: | |
2348 | */ | |
2349 | static void check_flags(unsigned long flags) | |
2350 | { | |
2351 | #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS) | |
2352 | if (!debug_locks) | |
2353 | return; | |
2354 | ||
2355 | if (irqs_disabled_flags(flags)) | |
2356 | DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled); | |
2357 | else | |
2358 | DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled); | |
2359 | ||
2360 | /* | |
2361 | * We dont accurately track softirq state in e.g. | |
2362 | * hardirq contexts (such as on 4KSTACKS), so only | |
2363 | * check if not in hardirq contexts: | |
2364 | */ | |
2365 | if (!hardirq_count()) { | |
2366 | if (softirq_count()) | |
2367 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); | |
2368 | else | |
2369 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); | |
2370 | } | |
2371 | ||
2372 | if (!debug_locks) | |
2373 | print_irqtrace_events(current); | |
2374 | #endif | |
2375 | } | |
2376 | ||
2377 | /* | |
2378 | * We are not always called with irqs disabled - do that here, | |
2379 | * and also avoid lockdep recursion: | |
2380 | */ | |
2381 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, | |
2382 | int trylock, int read, int check, unsigned long ip) | |
2383 | { | |
2384 | unsigned long flags; | |
2385 | ||
2386 | if (unlikely(current->lockdep_recursion)) | |
2387 | return; | |
2388 | ||
2389 | raw_local_irq_save(flags); | |
2390 | check_flags(flags); | |
2391 | ||
2392 | current->lockdep_recursion = 1; | |
2393 | __lock_acquire(lock, subclass, trylock, read, check, | |
2394 | irqs_disabled_flags(flags), ip); | |
2395 | current->lockdep_recursion = 0; | |
2396 | raw_local_irq_restore(flags); | |
2397 | } | |
2398 | ||
2399 | EXPORT_SYMBOL_GPL(lock_acquire); | |
2400 | ||
2401 | void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) | |
2402 | { | |
2403 | unsigned long flags; | |
2404 | ||
2405 | if (unlikely(current->lockdep_recursion)) | |
2406 | return; | |
2407 | ||
2408 | raw_local_irq_save(flags); | |
2409 | check_flags(flags); | |
2410 | current->lockdep_recursion = 1; | |
2411 | __lock_release(lock, nested, ip); | |
2412 | current->lockdep_recursion = 0; | |
2413 | raw_local_irq_restore(flags); | |
2414 | } | |
2415 | ||
2416 | EXPORT_SYMBOL_GPL(lock_release); | |
2417 | ||
2418 | /* | |
2419 | * Used by the testsuite, sanitize the validator state | |
2420 | * after a simulated failure: | |
2421 | */ | |
2422 | ||
2423 | void lockdep_reset(void) | |
2424 | { | |
2425 | unsigned long flags; | |
23d95a03 | 2426 | int i; |
fbb9ce95 IM |
2427 | |
2428 | raw_local_irq_save(flags); | |
2429 | current->curr_chain_key = 0; | |
2430 | current->lockdep_depth = 0; | |
2431 | current->lockdep_recursion = 0; | |
2432 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); | |
2433 | nr_hardirq_chains = 0; | |
2434 | nr_softirq_chains = 0; | |
2435 | nr_process_chains = 0; | |
2436 | debug_locks = 1; | |
23d95a03 IM |
2437 | for (i = 0; i < CHAINHASH_SIZE; i++) |
2438 | INIT_LIST_HEAD(chainhash_table + i); | |
fbb9ce95 IM |
2439 | raw_local_irq_restore(flags); |
2440 | } | |
2441 | ||
2442 | static void zap_class(struct lock_class *class) | |
2443 | { | |
2444 | int i; | |
2445 | ||
2446 | /* | |
2447 | * Remove all dependencies this lock is | |
2448 | * involved in: | |
2449 | */ | |
2450 | for (i = 0; i < nr_list_entries; i++) { | |
2451 | if (list_entries[i].class == class) | |
2452 | list_del_rcu(&list_entries[i].entry); | |
2453 | } | |
2454 | /* | |
2455 | * Unhash the class and remove it from the all_lock_classes list: | |
2456 | */ | |
2457 | list_del_rcu(&class->hash_entry); | |
2458 | list_del_rcu(&class->lock_entry); | |
2459 | ||
2460 | } | |
2461 | ||
2462 | static inline int within(void *addr, void *start, unsigned long size) | |
2463 | { | |
2464 | return addr >= start && addr < start + size; | |
2465 | } | |
2466 | ||
2467 | void lockdep_free_key_range(void *start, unsigned long size) | |
2468 | { | |
2469 | struct lock_class *class, *next; | |
2470 | struct list_head *head; | |
2471 | unsigned long flags; | |
2472 | int i; | |
2473 | ||
2474 | raw_local_irq_save(flags); | |
2475 | __raw_spin_lock(&hash_lock); | |
2476 | ||
2477 | /* | |
2478 | * Unhash all classes that were created by this module: | |
2479 | */ | |
2480 | for (i = 0; i < CLASSHASH_SIZE; i++) { | |
2481 | head = classhash_table + i; | |
2482 | if (list_empty(head)) | |
2483 | continue; | |
2484 | list_for_each_entry_safe(class, next, head, hash_entry) | |
2485 | if (within(class->key, start, size)) | |
2486 | zap_class(class); | |
2487 | } | |
2488 | ||
2489 | __raw_spin_unlock(&hash_lock); | |
2490 | raw_local_irq_restore(flags); | |
2491 | } | |
2492 | ||
2493 | void lockdep_reset_lock(struct lockdep_map *lock) | |
2494 | { | |
d6d897ce | 2495 | struct lock_class *class, *next; |
fbb9ce95 IM |
2496 | struct list_head *head; |
2497 | unsigned long flags; | |
2498 | int i, j; | |
2499 | ||
2500 | raw_local_irq_save(flags); | |
fbb9ce95 IM |
2501 | |
2502 | /* | |
d6d897ce IM |
2503 | * Remove all classes this lock might have: |
2504 | */ | |
2505 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { | |
2506 | /* | |
2507 | * If the class exists we look it up and zap it: | |
2508 | */ | |
2509 | class = look_up_lock_class(lock, j); | |
2510 | if (class) | |
2511 | zap_class(class); | |
2512 | } | |
2513 | /* | |
2514 | * Debug check: in the end all mapped classes should | |
2515 | * be gone. | |
fbb9ce95 | 2516 | */ |
d6d897ce | 2517 | __raw_spin_lock(&hash_lock); |
fbb9ce95 IM |
2518 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
2519 | head = classhash_table + i; | |
2520 | if (list_empty(head)) | |
2521 | continue; | |
2522 | list_for_each_entry_safe(class, next, head, hash_entry) { | |
d6d897ce IM |
2523 | if (unlikely(class == lock->class_cache)) { |
2524 | __raw_spin_unlock(&hash_lock); | |
2525 | DEBUG_LOCKS_WARN_ON(1); | |
2526 | goto out_restore; | |
fbb9ce95 IM |
2527 | } |
2528 | } | |
2529 | } | |
fbb9ce95 | 2530 | __raw_spin_unlock(&hash_lock); |
d6d897ce IM |
2531 | |
2532 | out_restore: | |
fbb9ce95 IM |
2533 | raw_local_irq_restore(flags); |
2534 | } | |
2535 | ||
2536 | void __init lockdep_init(void) | |
2537 | { | |
2538 | int i; | |
2539 | ||
2540 | /* | |
2541 | * Some architectures have their own start_kernel() | |
2542 | * code which calls lockdep_init(), while we also | |
2543 | * call lockdep_init() from the start_kernel() itself, | |
2544 | * and we want to initialize the hashes only once: | |
2545 | */ | |
2546 | if (lockdep_initialized) | |
2547 | return; | |
2548 | ||
2549 | for (i = 0; i < CLASSHASH_SIZE; i++) | |
2550 | INIT_LIST_HEAD(classhash_table + i); | |
2551 | ||
2552 | for (i = 0; i < CHAINHASH_SIZE; i++) | |
2553 | INIT_LIST_HEAD(chainhash_table + i); | |
2554 | ||
2555 | lockdep_initialized = 1; | |
2556 | } | |
2557 | ||
2558 | void __init lockdep_info(void) | |
2559 | { | |
2560 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); | |
2561 | ||
2562 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); | |
2563 | printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); | |
2564 | printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); | |
2565 | printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); | |
2566 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); | |
2567 | printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); | |
2568 | printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); | |
2569 | ||
2570 | printk(" memory used by lock dependency info: %lu kB\n", | |
2571 | (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + | |
2572 | sizeof(struct list_head) * CLASSHASH_SIZE + | |
2573 | sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + | |
2574 | sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + | |
2575 | sizeof(struct list_head) * CHAINHASH_SIZE) / 1024); | |
2576 | ||
2577 | printk(" per task-struct memory footprint: %lu bytes\n", | |
2578 | sizeof(struct held_lock) * MAX_LOCK_DEPTH); | |
2579 | ||
2580 | #ifdef CONFIG_DEBUG_LOCKDEP | |
2581 | if (lockdep_init_error) | |
2582 | printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n"); | |
2583 | #endif | |
2584 | } | |
2585 | ||
2586 | static inline int in_range(const void *start, const void *addr, const void *end) | |
2587 | { | |
2588 | return addr >= start && addr <= end; | |
2589 | } | |
2590 | ||
2591 | static void | |
2592 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, | |
55794a41 | 2593 | const void *mem_to, struct held_lock *hlock) |
fbb9ce95 IM |
2594 | { |
2595 | if (!debug_locks_off()) | |
2596 | return; | |
2597 | if (debug_locks_silent) | |
2598 | return; | |
2599 | ||
2600 | printk("\n=========================\n"); | |
2601 | printk( "[ BUG: held lock freed! ]\n"); | |
2602 | printk( "-------------------------\n"); | |
2603 | printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n", | |
2604 | curr->comm, curr->pid, mem_from, mem_to-1); | |
55794a41 | 2605 | print_lock(hlock); |
fbb9ce95 IM |
2606 | lockdep_print_held_locks(curr); |
2607 | ||
2608 | printk("\nstack backtrace:\n"); | |
2609 | dump_stack(); | |
2610 | } | |
2611 | ||
2612 | /* | |
2613 | * Called when kernel memory is freed (or unmapped), or if a lock | |
2614 | * is destroyed or reinitialized - this code checks whether there is | |
2615 | * any held lock in the memory range of <from> to <to>: | |
2616 | */ | |
2617 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) | |
2618 | { | |
2619 | const void *mem_to = mem_from + mem_len, *lock_from, *lock_to; | |
2620 | struct task_struct *curr = current; | |
2621 | struct held_lock *hlock; | |
2622 | unsigned long flags; | |
2623 | int i; | |
2624 | ||
2625 | if (unlikely(!debug_locks)) | |
2626 | return; | |
2627 | ||
2628 | local_irq_save(flags); | |
2629 | for (i = 0; i < curr->lockdep_depth; i++) { | |
2630 | hlock = curr->held_locks + i; | |
2631 | ||
2632 | lock_from = (void *)hlock->instance; | |
2633 | lock_to = (void *)(hlock->instance + 1); | |
2634 | ||
2635 | if (!in_range(mem_from, lock_from, mem_to) && | |
2636 | !in_range(mem_from, lock_to, mem_to)) | |
2637 | continue; | |
2638 | ||
55794a41 | 2639 | print_freed_lock_bug(curr, mem_from, mem_to, hlock); |
fbb9ce95 IM |
2640 | break; |
2641 | } | |
2642 | local_irq_restore(flags); | |
2643 | } | |
ed07536e | 2644 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
fbb9ce95 IM |
2645 | |
2646 | static void print_held_locks_bug(struct task_struct *curr) | |
2647 | { | |
2648 | if (!debug_locks_off()) | |
2649 | return; | |
2650 | if (debug_locks_silent) | |
2651 | return; | |
2652 | ||
2653 | printk("\n=====================================\n"); | |
2654 | printk( "[ BUG: lock held at task exit time! ]\n"); | |
2655 | printk( "-------------------------------------\n"); | |
2656 | printk("%s/%d is exiting with locks still held!\n", | |
2657 | curr->comm, curr->pid); | |
2658 | lockdep_print_held_locks(curr); | |
2659 | ||
2660 | printk("\nstack backtrace:\n"); | |
2661 | dump_stack(); | |
2662 | } | |
2663 | ||
2664 | void debug_check_no_locks_held(struct task_struct *task) | |
2665 | { | |
2666 | if (unlikely(task->lockdep_depth > 0)) | |
2667 | print_held_locks_bug(task); | |
2668 | } | |
2669 | ||
2670 | void debug_show_all_locks(void) | |
2671 | { | |
2672 | struct task_struct *g, *p; | |
2673 | int count = 10; | |
2674 | int unlock = 1; | |
2675 | ||
2676 | printk("\nShowing all locks held in the system:\n"); | |
2677 | ||
2678 | /* | |
2679 | * Here we try to get the tasklist_lock as hard as possible, | |
2680 | * if not successful after 2 seconds we ignore it (but keep | |
2681 | * trying). This is to enable a debug printout even if a | |
2682 | * tasklist_lock-holding task deadlocks or crashes. | |
2683 | */ | |
2684 | retry: | |
2685 | if (!read_trylock(&tasklist_lock)) { | |
2686 | if (count == 10) | |
2687 | printk("hm, tasklist_lock locked, retrying... "); | |
2688 | if (count) { | |
2689 | count--; | |
2690 | printk(" #%d", 10-count); | |
2691 | mdelay(200); | |
2692 | goto retry; | |
2693 | } | |
2694 | printk(" ignoring it.\n"); | |
2695 | unlock = 0; | |
2696 | } | |
2697 | if (count != 10) | |
2698 | printk(" locked it.\n"); | |
2699 | ||
2700 | do_each_thread(g, p) { | |
2701 | if (p->lockdep_depth) | |
2702 | lockdep_print_held_locks(p); | |
2703 | if (!unlock) | |
2704 | if (read_trylock(&tasklist_lock)) | |
2705 | unlock = 1; | |
2706 | } while_each_thread(g, p); | |
2707 | ||
2708 | printk("\n"); | |
2709 | printk("=============================================\n\n"); | |
2710 | ||
2711 | if (unlock) | |
2712 | read_unlock(&tasklist_lock); | |
2713 | } | |
2714 | ||
2715 | EXPORT_SYMBOL_GPL(debug_show_all_locks); | |
2716 | ||
2717 | void debug_show_held_locks(struct task_struct *task) | |
2718 | { | |
2719 | lockdep_print_held_locks(task); | |
2720 | } | |
2721 | ||
2722 | EXPORT_SYMBOL_GPL(debug_show_held_locks); | |
2723 |