Commit | Line | Data |
---|---|---|
38b4df64 | 1 | // SPDX-License-Identifier: GPL-2.0+ |
1da177e4 LT |
2 | /* |
3 | * Read-Copy Update mechanism for mutual exclusion | |
4 | * | |
01c1c660 | 5 | * Copyright IBM Corporation, 2001 |
1da177e4 LT |
6 | * |
7 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> | |
8 | * Manfred Spraul <manfred@colorfullife.com> | |
a71fca58 | 9 | * |
38b4df64 | 10 | * Based on the original work by Paul McKenney <paulmck@linux.ibm.com> |
1da177e4 LT |
11 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
12 | * Papers: | |
13 | * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf | |
14 | * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) | |
15 | * | |
16 | * For detailed explanation of Read-Copy Update mechanism see - | |
a71fca58 | 17 | * http://lse.sourceforge.net/locking/rcupdate.html |
1da177e4 LT |
18 | * |
19 | */ | |
20 | #include <linux/types.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/spinlock.h> | |
24 | #include <linux/smp.h> | |
25 | #include <linux/interrupt.h> | |
3f07c014 | 26 | #include <linux/sched/signal.h> |
b17b0153 | 27 | #include <linux/sched/debug.h> |
60063497 | 28 | #include <linux/atomic.h> |
1da177e4 | 29 | #include <linux/bitops.h> |
1da177e4 LT |
30 | #include <linux/percpu.h> |
31 | #include <linux/notifier.h> | |
1da177e4 | 32 | #include <linux/cpu.h> |
9331b315 | 33 | #include <linux/mutex.h> |
9984de1a | 34 | #include <linux/export.h> |
e3818b8d | 35 | #include <linux/hardirq.h> |
e3ebfb96 | 36 | #include <linux/delay.h> |
e77b7041 | 37 | #include <linux/moduleparam.h> |
8315f422 | 38 | #include <linux/kthread.h> |
4ff475ed | 39 | #include <linux/tick.h> |
f9411ebe | 40 | #include <linux/rcupdate_wait.h> |
78634061 | 41 | #include <linux/sched/isolation.h> |
a39f15b9 | 42 | #include <linux/kprobes.h> |
a35d1690 | 43 | #include <linux/slab.h> |
b38f57c1 | 44 | #include <linux/irq_work.h> |
5b3cc99b | 45 | #include <linux/rcupdate_trace.h> |
1da177e4 | 46 | |
29c00b4a | 47 | #define CREATE_TRACE_POINTS |
29c00b4a PM |
48 | |
49 | #include "rcu.h" | |
50 | ||
4102adab PM |
51 | #ifdef MODULE_PARAM_PREFIX |
52 | #undef MODULE_PARAM_PREFIX | |
53 | #endif | |
54 | #define MODULE_PARAM_PREFIX "rcupdate." | |
55 | ||
79cfea02 | 56 | #ifndef CONFIG_TINY_RCU |
1eac0075 JL |
57 | module_param(rcu_expedited, int, 0444); |
58 | module_param(rcu_normal, int, 0444); | |
36221e10 | 59 | static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT); |
ebb6d30d | 60 | #if !defined(CONFIG_PREEMPT_RT) || defined(CONFIG_NO_HZ_FULL) |
1eac0075 | 61 | module_param(rcu_normal_after_boot, int, 0444); |
36221e10 | 62 | #endif |
79cfea02 | 63 | #endif /* #ifndef CONFIG_TINY_RCU */ |
3e42ec1a | 64 | |
293e2421 | 65 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
d5671f6b | 66 | /** |
28875945 JFG |
67 | * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? |
68 | * @ret: Best guess answer if lockdep cannot be relied on | |
d5671f6b | 69 | * |
c28d5c09 | 70 | * Returns true if lockdep must be ignored, in which case ``*ret`` contains |
28875945 | 71 | * the best guess described below. Otherwise returns false, in which |
c28d5c09 | 72 | * case ``*ret`` tells the caller nothing and the caller should instead |
28875945 JFG |
73 | * consult lockdep. |
74 | * | |
c28d5c09 | 75 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an |
d5671f6b DV |
76 | * RCU-sched read-side critical section. In absence of |
77 | * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side | |
78 | * critical section unless it can prove otherwise. Note that disabling | |
79 | * of preemption (including disabling irqs) counts as an RCU-sched | |
80 | * read-side critical section. This is useful for debug checks in functions | |
81 | * that required that they be called within an RCU-sched read-side | |
82 | * critical section. | |
83 | * | |
84 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot | |
85 | * and while lockdep is disabled. | |
86 | * | |
28875945 | 87 | * Note that if the CPU is in the idle loop from an RCU point of view (ie: |
e67198cc | 88 | * that we are in the section between ct_idle_enter() and ct_idle_exit()) |
c28d5c09 | 89 | * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an |
28875945 JFG |
90 | * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are |
91 | * in such a section, considering these as in extended quiescent state, | |
92 | * so such a CPU is effectively never in an RCU read-side critical section | |
93 | * regardless of what RCU primitives it invokes. This state of affairs is | |
94 | * required --- we need to keep an RCU-free window in idle where the CPU may | |
95 | * possibly enter into low power mode. This way we can notice an extended | |
96 | * quiescent state to other CPUs that started a grace period. Otherwise | |
97 | * we would delay any grace period as long as we run in the idle task. | |
d5671f6b | 98 | * |
28875945 | 99 | * Similarly, we avoid claiming an RCU read lock held if the current |
d5671f6b DV |
100 | * CPU is offline. |
101 | */ | |
28875945 JFG |
102 | static bool rcu_read_lock_held_common(bool *ret) |
103 | { | |
104 | if (!debug_lockdep_rcu_enabled()) { | |
a66dbda7 | 105 | *ret = true; |
28875945 JFG |
106 | return true; |
107 | } | |
108 | if (!rcu_is_watching()) { | |
a66dbda7 | 109 | *ret = false; |
28875945 JFG |
110 | return true; |
111 | } | |
112 | if (!rcu_lockdep_current_cpu_online()) { | |
a66dbda7 | 113 | *ret = false; |
28875945 JFG |
114 | return true; |
115 | } | |
116 | return false; | |
117 | } | |
118 | ||
d5671f6b DV |
119 | int rcu_read_lock_sched_held(void) |
120 | { | |
28875945 | 121 | bool ret; |
d5671f6b | 122 | |
28875945 JFG |
123 | if (rcu_read_lock_held_common(&ret)) |
124 | return ret; | |
9147089b | 125 | return lock_is_held(&rcu_sched_lock_map) || !preemptible(); |
d5671f6b DV |
126 | } |
127 | EXPORT_SYMBOL(rcu_read_lock_sched_held); | |
128 | #endif | |
129 | ||
0d39482c PM |
130 | #ifndef CONFIG_TINY_RCU |
131 | ||
5a9be7c6 PM |
132 | /* |
133 | * Should expedited grace-period primitives always fall back to their | |
134 | * non-expedited counterparts? Intended for use within RCU. Note | |
135 | * that if the user specifies both rcu_expedited and rcu_normal, then | |
52d7e48b | 136 | * rcu_normal wins. (Except during the time period during boot from |
900b1028 | 137 | * when the first task is spawned until the rcu_set_runtime_mode() |
52d7e48b | 138 | * core_initcall() is invoked, at which point everything is expedited.) |
5a9be7c6 PM |
139 | */ |
140 | bool rcu_gp_is_normal(void) | |
141 | { | |
52d7e48b PM |
142 | return READ_ONCE(rcu_normal) && |
143 | rcu_scheduler_active != RCU_SCHEDULER_INIT; | |
5a9be7c6 | 144 | } |
4f2a848c | 145 | EXPORT_SYMBOL_GPL(rcu_gp_is_normal); |
5a9be7c6 | 146 | |
6efdda8b JFG |
147 | static atomic_t rcu_async_hurry_nesting = ATOMIC_INIT(1); |
148 | /* | |
149 | * Should call_rcu() callbacks be processed with urgency or are | |
150 | * they OK being executed with arbitrary delays? | |
151 | */ | |
152 | bool rcu_async_should_hurry(void) | |
153 | { | |
154 | return !IS_ENABLED(CONFIG_RCU_LAZY) || | |
155 | atomic_read(&rcu_async_hurry_nesting); | |
156 | } | |
157 | EXPORT_SYMBOL_GPL(rcu_async_should_hurry); | |
158 | ||
159 | /** | |
160 | * rcu_async_hurry - Make future async RCU callbacks not lazy. | |
161 | * | |
162 | * After a call to this function, future calls to call_rcu() | |
163 | * will be processed in a timely fashion. | |
164 | */ | |
165 | void rcu_async_hurry(void) | |
166 | { | |
167 | if (IS_ENABLED(CONFIG_RCU_LAZY)) | |
168 | atomic_inc(&rcu_async_hurry_nesting); | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(rcu_async_hurry); | |
0d39482c | 171 | |
6efdda8b JFG |
172 | /** |
173 | * rcu_async_relax - Make future async RCU callbacks lazy. | |
174 | * | |
175 | * After a call to this function, future calls to call_rcu() | |
176 | * will be processed in a lazy fashion. | |
177 | */ | |
178 | void rcu_async_relax(void) | |
179 | { | |
180 | if (IS_ENABLED(CONFIG_RCU_LAZY)) | |
181 | atomic_dec(&rcu_async_hurry_nesting); | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(rcu_async_relax); | |
184 | ||
185 | static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); | |
0d39482c PM |
186 | /* |
187 | * Should normal grace-period primitives be expedited? Intended for | |
188 | * use within RCU. Note that this function takes the rcu_expedited | |
52d7e48b PM |
189 | * sysfs/boot variable and rcu_scheduler_active into account as well |
190 | * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() | |
191 | * until rcu_gp_is_expedited() returns false is a -really- bad idea. | |
0d39482c PM |
192 | */ |
193 | bool rcu_gp_is_expedited(void) | |
194 | { | |
b823cafa | 195 | return rcu_expedited || atomic_read(&rcu_expedited_nesting); |
0d39482c PM |
196 | } |
197 | EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); | |
198 | ||
199 | /** | |
200 | * rcu_expedite_gp - Expedite future RCU grace periods | |
201 | * | |
202 | * After a call to this function, future calls to synchronize_rcu() and | |
203 | * friends act as the corresponding synchronize_rcu_expedited() function | |
204 | * had instead been called. | |
205 | */ | |
206 | void rcu_expedite_gp(void) | |
207 | { | |
208 | atomic_inc(&rcu_expedited_nesting); | |
209 | } | |
210 | EXPORT_SYMBOL_GPL(rcu_expedite_gp); | |
211 | ||
212 | /** | |
213 | * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation | |
214 | * | |
215 | * Undo a prior call to rcu_expedite_gp(). If all prior calls to | |
216 | * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), | |
217 | * and if the rcu_expedited sysfs/boot parameter is not set, then all | |
218 | * subsequent calls to synchronize_rcu() and friends will return to | |
219 | * their normal non-expedited behavior. | |
220 | */ | |
221 | void rcu_unexpedite_gp(void) | |
222 | { | |
223 | atomic_dec(&rcu_expedited_nesting); | |
224 | } | |
225 | EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); | |
226 | ||
59ee0326 PM |
227 | static bool rcu_boot_ended __read_mostly; |
228 | ||
ee42571f PM |
229 | /* |
230 | * Inform RCU of the end of the in-kernel boot sequence. | |
231 | */ | |
232 | void rcu_end_inkernel_boot(void) | |
233 | { | |
7c6094db | 234 | rcu_unexpedite_gp(); |
6efdda8b | 235 | rcu_async_relax(); |
3e42ec1a PM |
236 | if (rcu_normal_after_boot) |
237 | WRITE_ONCE(rcu_normal, 1); | |
e40bb921 | 238 | rcu_boot_ended = true; |
ee42571f | 239 | } |
0d39482c | 240 | |
59ee0326 PM |
241 | /* |
242 | * Let rcutorture know when it is OK to turn it up to eleven. | |
243 | */ | |
244 | bool rcu_inkernel_boot_has_ended(void) | |
245 | { | |
246 | return rcu_boot_ended; | |
ee42571f | 247 | } |
59ee0326 | 248 | EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended); |
0d39482c | 249 | |
79cfea02 PM |
250 | #endif /* #ifndef CONFIG_TINY_RCU */ |
251 | ||
900b1028 PM |
252 | /* |
253 | * Test each non-SRCU synchronous grace-period wait API. This is | |
254 | * useful just after a change in mode for these primitives, and | |
255 | * during early boot. | |
256 | */ | |
257 | void rcu_test_sync_prims(void) | |
258 | { | |
259 | if (!IS_ENABLED(CONFIG_PROVE_RCU)) | |
260 | return; | |
748bf47a | 261 | pr_info("Running RCU synchronous self tests\n"); |
900b1028 | 262 | synchronize_rcu(); |
900b1028 | 263 | synchronize_rcu_expedited(); |
900b1028 PM |
264 | } |
265 | ||
0cd7e350 | 266 | #if !defined(CONFIG_TINY_RCU) |
900b1028 PM |
267 | |
268 | /* | |
269 | * Switch to run-time mode once RCU has fully initialized. | |
270 | */ | |
271 | static int __init rcu_set_runtime_mode(void) | |
272 | { | |
273 | rcu_test_sync_prims(); | |
274 | rcu_scheduler_active = RCU_SCHEDULER_RUNNING; | |
a35d1690 | 275 | kfree_rcu_scheduler_running(); |
900b1028 PM |
276 | rcu_test_sync_prims(); |
277 | return 0; | |
278 | } | |
279 | core_initcall(rcu_set_runtime_mode); | |
280 | ||
0cd7e350 | 281 | #endif /* #if !defined(CONFIG_TINY_RCU) */ |
900b1028 | 282 | |
162cc279 PM |
283 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
284 | static struct lock_class_key rcu_lock_key; | |
de8f5e4f PZ |
285 | struct lockdep_map rcu_lock_map = { |
286 | .name = "rcu_read_lock", | |
287 | .key = &rcu_lock_key, | |
288 | .wait_type_outer = LD_WAIT_FREE, | |
a2e05ddd | 289 | .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT implies PREEMPT_RCU */ |
de8f5e4f | 290 | }; |
162cc279 | 291 | EXPORT_SYMBOL_GPL(rcu_lock_map); |
632ee200 PM |
292 | |
293 | static struct lock_class_key rcu_bh_lock_key; | |
de8f5e4f PZ |
294 | struct lockdep_map rcu_bh_lock_map = { |
295 | .name = "rcu_read_lock_bh", | |
296 | .key = &rcu_bh_lock_key, | |
297 | .wait_type_outer = LD_WAIT_FREE, | |
a2e05ddd | 298 | .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */ |
de8f5e4f | 299 | }; |
632ee200 PM |
300 | EXPORT_SYMBOL_GPL(rcu_bh_lock_map); |
301 | ||
302 | static struct lock_class_key rcu_sched_lock_key; | |
de8f5e4f PZ |
303 | struct lockdep_map rcu_sched_lock_map = { |
304 | .name = "rcu_read_lock_sched", | |
305 | .key = &rcu_sched_lock_key, | |
306 | .wait_type_outer = LD_WAIT_FREE, | |
307 | .wait_type_inner = LD_WAIT_SPIN, | |
308 | }; | |
632ee200 | 309 | EXPORT_SYMBOL_GPL(rcu_sched_lock_map); |
e3818b8d | 310 | |
f8466f94 | 311 | // Tell lockdep when RCU callbacks are being invoked. |
24ef659a PM |
312 | static struct lock_class_key rcu_callback_key; |
313 | struct lockdep_map rcu_callback_map = | |
314 | STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key); | |
315 | EXPORT_SYMBOL_GPL(rcu_callback_map); | |
316 | ||
ff5c4f5c | 317 | noinstr int notrace debug_lockdep_rcu_enabled(void) |
bc293d62 | 318 | { |
30668200 | 319 | return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) && |
bc293d62 PM |
320 | current->lockdep_recursion == 0; |
321 | } | |
322 | EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); | |
323 | ||
85b39d30 ON |
324 | /** |
325 | * rcu_read_lock_held() - might we be in RCU read-side critical section? | |
326 | * | |
327 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU | |
328 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
329 | * this assumes we are in an RCU read-side critical section unless it can | |
330 | * prove otherwise. This is useful for debug checks in functions that | |
331 | * require that they be called within an RCU read-side critical section. | |
332 | * | |
333 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot | |
334 | * and while lockdep is disabled. | |
335 | * | |
336 | * Note that rcu_read_lock() and the matching rcu_read_unlock() must | |
337 | * occur in the same context, for example, it is illegal to invoke | |
338 | * rcu_read_unlock() in process context if the matching rcu_read_lock() | |
339 | * was invoked from within an irq handler. | |
340 | * | |
341 | * Note that rcu_read_lock() is disallowed if the CPU is either idle or | |
342 | * offline from an RCU perspective, so check for those as well. | |
343 | */ | |
344 | int rcu_read_lock_held(void) | |
345 | { | |
28875945 JFG |
346 | bool ret; |
347 | ||
348 | if (rcu_read_lock_held_common(&ret)) | |
349 | return ret; | |
85b39d30 ON |
350 | return lock_is_held(&rcu_lock_map); |
351 | } | |
352 | EXPORT_SYMBOL_GPL(rcu_read_lock_held); | |
353 | ||
e3818b8d | 354 | /** |
ca5ecddf | 355 | * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? |
e3818b8d PM |
356 | * |
357 | * Check for bottom half being disabled, which covers both the | |
358 | * CONFIG_PROVE_RCU and not cases. Note that if someone uses | |
359 | * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) | |
ca5ecddf PM |
360 | * will show the situation. This is useful for debug checks in functions |
361 | * that require that they be called within an RCU read-side critical | |
362 | * section. | |
e3818b8d PM |
363 | * |
364 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. | |
c0d6d01b | 365 | * |
82fcecfa | 366 | * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or |
c0d6d01b | 367 | * offline from an RCU perspective, so check for those as well. |
e3818b8d PM |
368 | */ |
369 | int rcu_read_lock_bh_held(void) | |
370 | { | |
28875945 JFG |
371 | bool ret; |
372 | ||
373 | if (rcu_read_lock_held_common(&ret)) | |
374 | return ret; | |
773e3f93 | 375 | return in_softirq() || irqs_disabled(); |
e3818b8d PM |
376 | } |
377 | EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); | |
378 | ||
28875945 JFG |
379 | int rcu_read_lock_any_held(void) |
380 | { | |
381 | bool ret; | |
382 | ||
383 | if (rcu_read_lock_held_common(&ret)) | |
384 | return ret; | |
385 | if (lock_is_held(&rcu_lock_map) || | |
386 | lock_is_held(&rcu_bh_lock_map) || | |
387 | lock_is_held(&rcu_sched_lock_map)) | |
388 | return 1; | |
389 | return !preemptible(); | |
390 | } | |
391 | EXPORT_SYMBOL_GPL(rcu_read_lock_any_held); | |
392 | ||
e3818b8d PM |
393 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
394 | ||
ee376dbd PM |
395 | /** |
396 | * wakeme_after_rcu() - Callback function to awaken a task after grace period | |
397 | * @head: Pointer to rcu_head member within rcu_synchronize structure | |
398 | * | |
399 | * Awaken the corresponding task now that a grace period has elapsed. | |
fbf6bfca | 400 | */ |
ee376dbd | 401 | void wakeme_after_rcu(struct rcu_head *head) |
21a1ea9e | 402 | { |
01c1c660 PM |
403 | struct rcu_synchronize *rcu; |
404 | ||
405 | rcu = container_of(head, struct rcu_synchronize, head); | |
406 | complete(&rcu->completion); | |
21a1ea9e | 407 | } |
ec90a194 | 408 | EXPORT_SYMBOL_GPL(wakeme_after_rcu); |
ee84b824 | 409 | |
ec90a194 PM |
410 | void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, |
411 | struct rcu_synchronize *rs_array) | |
2c42818e | 412 | { |
ec90a194 | 413 | int i; |
68ab0b42 | 414 | int j; |
ec90a194 | 415 | |
06462efc | 416 | /* Initialize and register callbacks for each crcu_array element. */ |
ec90a194 PM |
417 | for (i = 0; i < n; i++) { |
418 | if (checktiny && | |
309ba859 | 419 | (crcu_array[i] == call_rcu)) { |
ec90a194 PM |
420 | might_sleep(); |
421 | continue; | |
422 | } | |
68ab0b42 PM |
423 | for (j = 0; j < i; j++) |
424 | if (crcu_array[j] == crcu_array[i]) | |
425 | break; | |
7ee880b7 WY |
426 | if (j == i) { |
427 | init_rcu_head_on_stack(&rs_array[i].head); | |
428 | init_completion(&rs_array[i].completion); | |
68ab0b42 | 429 | (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); |
7ee880b7 | 430 | } |
ec90a194 PM |
431 | } |
432 | ||
433 | /* Wait for all callbacks to be invoked. */ | |
434 | for (i = 0; i < n; i++) { | |
435 | if (checktiny && | |
309ba859 | 436 | (crcu_array[i] == call_rcu)) |
ec90a194 | 437 | continue; |
68ab0b42 PM |
438 | for (j = 0; j < i; j++) |
439 | if (crcu_array[j] == crcu_array[i]) | |
440 | break; | |
7ee880b7 | 441 | if (j == i) { |
68ab0b42 | 442 | wait_for_completion(&rs_array[i].completion); |
7ee880b7 WY |
443 | destroy_rcu_head_on_stack(&rs_array[i].head); |
444 | } | |
ec90a194 | 445 | } |
2c42818e | 446 | } |
ec90a194 | 447 | EXPORT_SYMBOL_GPL(__wait_rcu_gp); |
2c42818e | 448 | |
58d4292b IM |
449 | void finish_rcuwait(struct rcuwait *w) |
450 | { | |
451 | rcu_assign_pointer(w->task, NULL); | |
452 | __set_current_state(TASK_RUNNING); | |
453 | } | |
454 | EXPORT_SYMBOL_GPL(finish_rcuwait); | |
455 | ||
551d55a9 | 456 | #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD |
546a9d85 | 457 | void init_rcu_head(struct rcu_head *head) |
551d55a9 MD |
458 | { |
459 | debug_object_init(head, &rcuhead_debug_descr); | |
460 | } | |
156baec3 | 461 | EXPORT_SYMBOL_GPL(init_rcu_head); |
551d55a9 | 462 | |
546a9d85 | 463 | void destroy_rcu_head(struct rcu_head *head) |
551d55a9 MD |
464 | { |
465 | debug_object_free(head, &rcuhead_debug_descr); | |
466 | } | |
156baec3 | 467 | EXPORT_SYMBOL_GPL(destroy_rcu_head); |
551d55a9 | 468 | |
b9fdac7f | 469 | static bool rcuhead_is_static_object(void *addr) |
551d55a9 | 470 | { |
b9fdac7f | 471 | return true; |
551d55a9 MD |
472 | } |
473 | ||
474 | /** | |
475 | * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects | |
476 | * @head: pointer to rcu_head structure to be initialized | |
477 | * | |
478 | * This function informs debugobjects of a new rcu_head structure that | |
479 | * has been allocated as an auto variable on the stack. This function | |
480 | * is not required for rcu_head structures that are statically defined or | |
481 | * that are dynamically allocated on the heap. This function has no | |
482 | * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
483 | */ | |
484 | void init_rcu_head_on_stack(struct rcu_head *head) | |
485 | { | |
486 | debug_object_init_on_stack(head, &rcuhead_debug_descr); | |
487 | } | |
488 | EXPORT_SYMBOL_GPL(init_rcu_head_on_stack); | |
489 | ||
490 | /** | |
491 | * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects | |
492 | * @head: pointer to rcu_head structure to be initialized | |
493 | * | |
494 | * This function informs debugobjects that an on-stack rcu_head structure | |
495 | * is about to go out of scope. As with init_rcu_head_on_stack(), this | |
496 | * function is not required for rcu_head structures that are statically | |
497 | * defined or that are dynamically allocated on the heap. Also as with | |
498 | * init_rcu_head_on_stack(), this function has no effect for | |
499 | * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
500 | */ | |
501 | void destroy_rcu_head_on_stack(struct rcu_head *head) | |
502 | { | |
503 | debug_object_free(head, &rcuhead_debug_descr); | |
504 | } | |
505 | EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); | |
506 | ||
f9e62f31 | 507 | const struct debug_obj_descr rcuhead_debug_descr = { |
551d55a9 | 508 | .name = "rcu_head", |
b9fdac7f | 509 | .is_static_object = rcuhead_is_static_object, |
551d55a9 MD |
510 | }; |
511 | EXPORT_SYMBOL_GPL(rcuhead_debug_descr); | |
512 | #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ | |
91afaf30 | 513 | |
b3e627d3 | 514 | #if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE) |
e66c33d5 | 515 | void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, |
52494535 PM |
516 | unsigned long secs, |
517 | unsigned long c_old, unsigned long c) | |
91afaf30 | 518 | { |
52494535 | 519 | trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); |
91afaf30 PM |
520 | } |
521 | EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); | |
522 | #else | |
52494535 PM |
523 | #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ |
524 | do { } while (0) | |
91afaf30 | 525 | #endif |
6bfc09e2 | 526 | |
c682db55 PM |
527 | #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) |
528 | /* Get rcutorture access to sched_setaffinity(). */ | |
529 | long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask) | |
530 | { | |
531 | int ret; | |
532 | ||
533 | ret = sched_setaffinity(pid, in_mask); | |
534 | WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret); | |
535 | return ret; | |
536 | } | |
537 | EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity); | |
538 | #endif | |
539 | ||
6bfc09e2 | 540 | #ifdef CONFIG_RCU_STALL_COMMON |
cdc694b2 PM |
541 | int rcu_cpu_stall_ftrace_dump __read_mostly; |
542 | module_param(rcu_cpu_stall_ftrace_dump, int, 0644); | |
58c53360 | 543 | int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings. |
f22ce091 | 544 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); |
6bfc09e2 | 545 | module_param(rcu_cpu_stall_suppress, int, 0644); |
10462d6f | 546 | int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; |
6bfc09e2 | 547 | module_param(rcu_cpu_stall_timeout, int, 0644); |
28b3ae42 UR |
548 | int rcu_exp_cpu_stall_timeout __read_mostly = CONFIG_RCU_EXP_CPU_STALL_TIMEOUT; |
549 | module_param(rcu_exp_cpu_stall_timeout, int, 0644); | |
be42f00b ZL |
550 | int rcu_cpu_stall_cputime __read_mostly = IS_ENABLED(CONFIG_RCU_CPU_STALL_CPUTIME); |
551 | module_param(rcu_cpu_stall_cputime, int, 0644); | |
92987fe8 PM |
552 | bool rcu_exp_stall_task_details __read_mostly; |
553 | module_param(rcu_exp_stall_task_details, bool, 0644); | |
6bfc09e2 | 554 | #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ |
8315f422 | 555 | |
58c53360 PM |
556 | // Suppress boot-time RCU CPU stall warnings and rcutorture writer stall |
557 | // warnings. Also used by rcutorture even if stall warnings are excluded. | |
558 | int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls. | |
559 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot); | |
560 | module_param(rcu_cpu_stall_suppress_at_boot, int, 0444); | |
561 | ||
414c1238 PM |
562 | /** |
563 | * get_completed_synchronize_rcu - Return a pre-completed polled state cookie | |
564 | * | |
565 | * Returns a value that will always be treated by functions like | |
566 | * poll_state_synchronize_rcu() as a cookie whose grace period has already | |
567 | * completed. | |
568 | */ | |
569 | unsigned long get_completed_synchronize_rcu(void) | |
570 | { | |
571 | return RCU_GET_STATE_COMPLETED; | |
572 | } | |
573 | EXPORT_SYMBOL_GPL(get_completed_synchronize_rcu); | |
574 | ||
aa23c6fb PK |
575 | #ifdef CONFIG_PROVE_RCU |
576 | ||
577 | /* | |
72ce30dd | 578 | * Early boot self test parameters. |
aa23c6fb PK |
579 | */ |
580 | static bool rcu_self_test; | |
aa23c6fb | 581 | module_param(rcu_self_test, bool, 0444); |
aa23c6fb PK |
582 | |
583 | static int rcu_self_test_counter; | |
584 | ||
585 | static void test_callback(struct rcu_head *r) | |
586 | { | |
587 | rcu_self_test_counter++; | |
588 | pr_info("RCU test callback executed %d\n", rcu_self_test_counter); | |
589 | } | |
590 | ||
e0fcba9a | 591 | DEFINE_STATIC_SRCU(early_srcu); |
0a580fa6 | 592 | static unsigned long early_srcu_cookie; |
e0fcba9a | 593 | |
a35d1690 BP |
594 | struct early_boot_kfree_rcu { |
595 | struct rcu_head rh; | |
596 | }; | |
597 | ||
aa23c6fb PK |
598 | static void early_boot_test_call_rcu(void) |
599 | { | |
600 | static struct rcu_head head; | |
efa3c40c | 601 | int idx; |
e0fcba9a | 602 | static struct rcu_head shead; |
a35d1690 | 603 | struct early_boot_kfree_rcu *rhp; |
aa23c6fb | 604 | |
efa3c40c PM |
605 | idx = srcu_down_read(&early_srcu); |
606 | srcu_up_read(&early_srcu, idx); | |
aa23c6fb | 607 | call_rcu(&head, test_callback); |
0cd7e350 PM |
608 | early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu); |
609 | call_srcu(&early_srcu, &shead, test_callback); | |
a35d1690 BP |
610 | rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); |
611 | if (!WARN_ON_ONCE(!rhp)) | |
612 | kfree_rcu(rhp, rh); | |
aa23c6fb PK |
613 | } |
614 | ||
615 | void rcu_early_boot_tests(void) | |
616 | { | |
617 | pr_info("Running RCU self tests\n"); | |
618 | ||
619 | if (rcu_self_test) | |
620 | early_boot_test_call_rcu(); | |
52d7e48b | 621 | rcu_test_sync_prims(); |
aa23c6fb PK |
622 | } |
623 | ||
624 | static int rcu_verify_early_boot_tests(void) | |
625 | { | |
626 | int ret = 0; | |
627 | int early_boot_test_counter = 0; | |
628 | ||
629 | if (rcu_self_test) { | |
630 | early_boot_test_counter++; | |
631 | rcu_barrier(); | |
0cd7e350 PM |
632 | early_boot_test_counter++; |
633 | srcu_barrier(&early_srcu); | |
634 | WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie)); | |
66ea1029 | 635 | cleanup_srcu_struct(&early_srcu); |
aa23c6fb | 636 | } |
aa23c6fb PK |
637 | if (rcu_self_test_counter != early_boot_test_counter) { |
638 | WARN_ON(1); | |
639 | ret = -1; | |
640 | } | |
641 | ||
642 | return ret; | |
643 | } | |
644 | late_initcall(rcu_verify_early_boot_tests); | |
645 | #else | |
646 | void rcu_early_boot_tests(void) {} | |
647 | #endif /* CONFIG_PROVE_RCU */ | |
59d80fd8 | 648 | |
eacd6f04 PM |
649 | #include "tasks.h" |
650 | ||
59d80fd8 PM |
651 | #ifndef CONFIG_TINY_RCU |
652 | ||
653 | /* | |
654 | * Print any significant non-default boot-time settings. | |
655 | */ | |
656 | void __init rcupdate_announce_bootup_oddness(void) | |
657 | { | |
658 | if (rcu_normal) | |
659 | pr_info("\tNo expedited grace period (rcu_normal).\n"); | |
660 | else if (rcu_normal_after_boot) | |
661 | pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n"); | |
662 | else if (rcu_expedited) | |
663 | pr_info("\tAll grace periods are expedited (rcu_expedited).\n"); | |
664 | if (rcu_cpu_stall_suppress) | |
665 | pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n"); | |
666 | if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT) | |
667 | pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout); | |
668 | rcu_tasks_bootup_oddness(); | |
669 | } | |
670 | ||
671 | #endif /* #ifndef CONFIG_TINY_RCU */ |