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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> |
1da177e4 | 45 | |
29c00b4a | 46 | #define CREATE_TRACE_POINTS |
29c00b4a PM |
47 | |
48 | #include "rcu.h" | |
49 | ||
4102adab PM |
50 | #ifdef MODULE_PARAM_PREFIX |
51 | #undef MODULE_PARAM_PREFIX | |
52 | #endif | |
53 | #define MODULE_PARAM_PREFIX "rcupdate." | |
54 | ||
c76e7e0b PM |
55 | #ifndef data_race |
56 | #define data_race(expr) \ | |
57 | ({ \ | |
58 | expr; \ | |
59 | }) | |
60 | #endif | |
61 | #ifndef ASSERT_EXCLUSIVE_WRITER | |
62 | #define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0) | |
63 | #endif | |
64 | #ifndef ASSERT_EXCLUSIVE_ACCESS | |
65 | #define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0) | |
66 | #endif | |
67 | ||
79cfea02 | 68 | #ifndef CONFIG_TINY_RCU |
3705b88d | 69 | module_param(rcu_expedited, int, 0); |
5a9be7c6 | 70 | module_param(rcu_normal, int, 0); |
3e42ec1a PM |
71 | static int rcu_normal_after_boot; |
72 | module_param(rcu_normal_after_boot, int, 0); | |
79cfea02 | 73 | #endif /* #ifndef CONFIG_TINY_RCU */ |
3e42ec1a | 74 | |
293e2421 | 75 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
d5671f6b | 76 | /** |
28875945 JFG |
77 | * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section? |
78 | * @ret: Best guess answer if lockdep cannot be relied on | |
d5671f6b | 79 | * |
c28d5c09 | 80 | * Returns true if lockdep must be ignored, in which case ``*ret`` contains |
28875945 | 81 | * the best guess described below. Otherwise returns false, in which |
c28d5c09 | 82 | * case ``*ret`` tells the caller nothing and the caller should instead |
28875945 JFG |
83 | * consult lockdep. |
84 | * | |
c28d5c09 | 85 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an |
d5671f6b DV |
86 | * RCU-sched read-side critical section. In absence of |
87 | * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side | |
88 | * critical section unless it can prove otherwise. Note that disabling | |
89 | * of preemption (including disabling irqs) counts as an RCU-sched | |
90 | * read-side critical section. This is useful for debug checks in functions | |
91 | * that required that they be called within an RCU-sched read-side | |
92 | * critical section. | |
93 | * | |
94 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot | |
95 | * and while lockdep is disabled. | |
96 | * | |
28875945 JFG |
97 | * Note that if the CPU is in the idle loop from an RCU point of view (ie: |
98 | * that we are in the section between rcu_idle_enter() and rcu_idle_exit()) | |
c28d5c09 | 99 | * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an |
28875945 JFG |
100 | * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are |
101 | * in such a section, considering these as in extended quiescent state, | |
102 | * so such a CPU is effectively never in an RCU read-side critical section | |
103 | * regardless of what RCU primitives it invokes. This state of affairs is | |
104 | * required --- we need to keep an RCU-free window in idle where the CPU may | |
105 | * possibly enter into low power mode. This way we can notice an extended | |
106 | * quiescent state to other CPUs that started a grace period. Otherwise | |
107 | * we would delay any grace period as long as we run in the idle task. | |
d5671f6b | 108 | * |
28875945 | 109 | * Similarly, we avoid claiming an RCU read lock held if the current |
d5671f6b DV |
110 | * CPU is offline. |
111 | */ | |
28875945 JFG |
112 | static bool rcu_read_lock_held_common(bool *ret) |
113 | { | |
114 | if (!debug_lockdep_rcu_enabled()) { | |
a66dbda7 | 115 | *ret = true; |
28875945 JFG |
116 | return true; |
117 | } | |
118 | if (!rcu_is_watching()) { | |
a66dbda7 | 119 | *ret = false; |
28875945 JFG |
120 | return true; |
121 | } | |
122 | if (!rcu_lockdep_current_cpu_online()) { | |
a66dbda7 | 123 | *ret = false; |
28875945 JFG |
124 | return true; |
125 | } | |
126 | return false; | |
127 | } | |
128 | ||
d5671f6b DV |
129 | int rcu_read_lock_sched_held(void) |
130 | { | |
28875945 | 131 | bool ret; |
d5671f6b | 132 | |
28875945 JFG |
133 | if (rcu_read_lock_held_common(&ret)) |
134 | return ret; | |
9147089b | 135 | return lock_is_held(&rcu_sched_lock_map) || !preemptible(); |
d5671f6b DV |
136 | } |
137 | EXPORT_SYMBOL(rcu_read_lock_sched_held); | |
138 | #endif | |
139 | ||
0d39482c PM |
140 | #ifndef CONFIG_TINY_RCU |
141 | ||
5a9be7c6 PM |
142 | /* |
143 | * Should expedited grace-period primitives always fall back to their | |
144 | * non-expedited counterparts? Intended for use within RCU. Note | |
145 | * that if the user specifies both rcu_expedited and rcu_normal, then | |
52d7e48b | 146 | * rcu_normal wins. (Except during the time period during boot from |
900b1028 | 147 | * when the first task is spawned until the rcu_set_runtime_mode() |
52d7e48b | 148 | * core_initcall() is invoked, at which point everything is expedited.) |
5a9be7c6 PM |
149 | */ |
150 | bool rcu_gp_is_normal(void) | |
151 | { | |
52d7e48b PM |
152 | return READ_ONCE(rcu_normal) && |
153 | rcu_scheduler_active != RCU_SCHEDULER_INIT; | |
5a9be7c6 | 154 | } |
4f2a848c | 155 | EXPORT_SYMBOL_GPL(rcu_gp_is_normal); |
5a9be7c6 | 156 | |
7c6094db | 157 | static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); |
0d39482c PM |
158 | |
159 | /* | |
160 | * Should normal grace-period primitives be expedited? Intended for | |
161 | * use within RCU. Note that this function takes the rcu_expedited | |
52d7e48b PM |
162 | * sysfs/boot variable and rcu_scheduler_active into account as well |
163 | * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() | |
164 | * until rcu_gp_is_expedited() returns false is a -really- bad idea. | |
0d39482c PM |
165 | */ |
166 | bool rcu_gp_is_expedited(void) | |
167 | { | |
b823cafa | 168 | return rcu_expedited || atomic_read(&rcu_expedited_nesting); |
0d39482c PM |
169 | } |
170 | EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); | |
171 | ||
172 | /** | |
173 | * rcu_expedite_gp - Expedite future RCU grace periods | |
174 | * | |
175 | * After a call to this function, future calls to synchronize_rcu() and | |
176 | * friends act as the corresponding synchronize_rcu_expedited() function | |
177 | * had instead been called. | |
178 | */ | |
179 | void rcu_expedite_gp(void) | |
180 | { | |
181 | atomic_inc(&rcu_expedited_nesting); | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(rcu_expedite_gp); | |
184 | ||
185 | /** | |
186 | * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation | |
187 | * | |
188 | * Undo a prior call to rcu_expedite_gp(). If all prior calls to | |
189 | * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), | |
190 | * and if the rcu_expedited sysfs/boot parameter is not set, then all | |
191 | * subsequent calls to synchronize_rcu() and friends will return to | |
192 | * their normal non-expedited behavior. | |
193 | */ | |
194 | void rcu_unexpedite_gp(void) | |
195 | { | |
196 | atomic_dec(&rcu_expedited_nesting); | |
197 | } | |
198 | EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); | |
199 | ||
59ee0326 PM |
200 | static bool rcu_boot_ended __read_mostly; |
201 | ||
ee42571f PM |
202 | /* |
203 | * Inform RCU of the end of the in-kernel boot sequence. | |
204 | */ | |
205 | void rcu_end_inkernel_boot(void) | |
206 | { | |
7c6094db | 207 | rcu_unexpedite_gp(); |
3e42ec1a PM |
208 | if (rcu_normal_after_boot) |
209 | WRITE_ONCE(rcu_normal, 1); | |
59ee0326 | 210 | rcu_boot_ended = 1; |
ee42571f | 211 | } |
0d39482c | 212 | |
59ee0326 PM |
213 | /* |
214 | * Let rcutorture know when it is OK to turn it up to eleven. | |
215 | */ | |
216 | bool rcu_inkernel_boot_has_ended(void) | |
217 | { | |
218 | return rcu_boot_ended; | |
ee42571f | 219 | } |
59ee0326 | 220 | EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended); |
0d39482c | 221 | |
79cfea02 PM |
222 | #endif /* #ifndef CONFIG_TINY_RCU */ |
223 | ||
900b1028 PM |
224 | /* |
225 | * Test each non-SRCU synchronous grace-period wait API. This is | |
226 | * useful just after a change in mode for these primitives, and | |
227 | * during early boot. | |
228 | */ | |
229 | void rcu_test_sync_prims(void) | |
230 | { | |
231 | if (!IS_ENABLED(CONFIG_PROVE_RCU)) | |
232 | return; | |
233 | synchronize_rcu(); | |
900b1028 | 234 | synchronize_rcu_expedited(); |
900b1028 PM |
235 | } |
236 | ||
237 | #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) | |
238 | ||
239 | /* | |
240 | * Switch to run-time mode once RCU has fully initialized. | |
241 | */ | |
242 | static int __init rcu_set_runtime_mode(void) | |
243 | { | |
244 | rcu_test_sync_prims(); | |
245 | rcu_scheduler_active = RCU_SCHEDULER_RUNNING; | |
a35d1690 | 246 | kfree_rcu_scheduler_running(); |
900b1028 PM |
247 | rcu_test_sync_prims(); |
248 | return 0; | |
249 | } | |
250 | core_initcall(rcu_set_runtime_mode); | |
251 | ||
252 | #endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */ | |
253 | ||
162cc279 PM |
254 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
255 | static struct lock_class_key rcu_lock_key; | |
de8f5e4f PZ |
256 | struct lockdep_map rcu_lock_map = { |
257 | .name = "rcu_read_lock", | |
258 | .key = &rcu_lock_key, | |
259 | .wait_type_outer = LD_WAIT_FREE, | |
260 | .wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */ | |
261 | }; | |
162cc279 | 262 | EXPORT_SYMBOL_GPL(rcu_lock_map); |
632ee200 PM |
263 | |
264 | static struct lock_class_key rcu_bh_lock_key; | |
de8f5e4f PZ |
265 | struct lockdep_map rcu_bh_lock_map = { |
266 | .name = "rcu_read_lock_bh", | |
267 | .key = &rcu_bh_lock_key, | |
268 | .wait_type_outer = LD_WAIT_FREE, | |
269 | .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */ | |
270 | }; | |
632ee200 PM |
271 | EXPORT_SYMBOL_GPL(rcu_bh_lock_map); |
272 | ||
273 | static struct lock_class_key rcu_sched_lock_key; | |
de8f5e4f PZ |
274 | struct lockdep_map rcu_sched_lock_map = { |
275 | .name = "rcu_read_lock_sched", | |
276 | .key = &rcu_sched_lock_key, | |
277 | .wait_type_outer = LD_WAIT_FREE, | |
278 | .wait_type_inner = LD_WAIT_SPIN, | |
279 | }; | |
632ee200 | 280 | EXPORT_SYMBOL_GPL(rcu_sched_lock_map); |
e3818b8d | 281 | |
24ef659a PM |
282 | static struct lock_class_key rcu_callback_key; |
283 | struct lockdep_map rcu_callback_map = | |
284 | STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key); | |
285 | EXPORT_SYMBOL_GPL(rcu_callback_map); | |
286 | ||
ff5c4f5c | 287 | noinstr int notrace debug_lockdep_rcu_enabled(void) |
bc293d62 | 288 | { |
52d7e48b | 289 | return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks && |
bc293d62 PM |
290 | current->lockdep_recursion == 0; |
291 | } | |
292 | EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); | |
293 | ||
85b39d30 ON |
294 | /** |
295 | * rcu_read_lock_held() - might we be in RCU read-side critical section? | |
296 | * | |
297 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU | |
298 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
299 | * this assumes we are in an RCU read-side critical section unless it can | |
300 | * prove otherwise. This is useful for debug checks in functions that | |
301 | * require that they be called within an RCU read-side critical section. | |
302 | * | |
303 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot | |
304 | * and while lockdep is disabled. | |
305 | * | |
306 | * Note that rcu_read_lock() and the matching rcu_read_unlock() must | |
307 | * occur in the same context, for example, it is illegal to invoke | |
308 | * rcu_read_unlock() in process context if the matching rcu_read_lock() | |
309 | * was invoked from within an irq handler. | |
310 | * | |
311 | * Note that rcu_read_lock() is disallowed if the CPU is either idle or | |
312 | * offline from an RCU perspective, so check for those as well. | |
313 | */ | |
314 | int rcu_read_lock_held(void) | |
315 | { | |
28875945 JFG |
316 | bool ret; |
317 | ||
318 | if (rcu_read_lock_held_common(&ret)) | |
319 | return ret; | |
85b39d30 ON |
320 | return lock_is_held(&rcu_lock_map); |
321 | } | |
322 | EXPORT_SYMBOL_GPL(rcu_read_lock_held); | |
323 | ||
e3818b8d | 324 | /** |
ca5ecddf | 325 | * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? |
e3818b8d PM |
326 | * |
327 | * Check for bottom half being disabled, which covers both the | |
328 | * CONFIG_PROVE_RCU and not cases. Note that if someone uses | |
329 | * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) | |
ca5ecddf PM |
330 | * will show the situation. This is useful for debug checks in functions |
331 | * that require that they be called within an RCU read-side critical | |
332 | * section. | |
e3818b8d PM |
333 | * |
334 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. | |
c0d6d01b | 335 | * |
82fcecfa | 336 | * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or |
c0d6d01b | 337 | * offline from an RCU perspective, so check for those as well. |
e3818b8d PM |
338 | */ |
339 | int rcu_read_lock_bh_held(void) | |
340 | { | |
28875945 JFG |
341 | bool ret; |
342 | ||
343 | if (rcu_read_lock_held_common(&ret)) | |
344 | return ret; | |
773e3f93 | 345 | return in_softirq() || irqs_disabled(); |
e3818b8d PM |
346 | } |
347 | EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); | |
348 | ||
28875945 JFG |
349 | int rcu_read_lock_any_held(void) |
350 | { | |
351 | bool ret; | |
352 | ||
353 | if (rcu_read_lock_held_common(&ret)) | |
354 | return ret; | |
355 | if (lock_is_held(&rcu_lock_map) || | |
356 | lock_is_held(&rcu_bh_lock_map) || | |
357 | lock_is_held(&rcu_sched_lock_map)) | |
358 | return 1; | |
359 | return !preemptible(); | |
360 | } | |
361 | EXPORT_SYMBOL_GPL(rcu_read_lock_any_held); | |
362 | ||
e3818b8d PM |
363 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
364 | ||
ee376dbd PM |
365 | /** |
366 | * wakeme_after_rcu() - Callback function to awaken a task after grace period | |
367 | * @head: Pointer to rcu_head member within rcu_synchronize structure | |
368 | * | |
369 | * Awaken the corresponding task now that a grace period has elapsed. | |
fbf6bfca | 370 | */ |
ee376dbd | 371 | void wakeme_after_rcu(struct rcu_head *head) |
21a1ea9e | 372 | { |
01c1c660 PM |
373 | struct rcu_synchronize *rcu; |
374 | ||
375 | rcu = container_of(head, struct rcu_synchronize, head); | |
376 | complete(&rcu->completion); | |
21a1ea9e | 377 | } |
ec90a194 | 378 | EXPORT_SYMBOL_GPL(wakeme_after_rcu); |
ee84b824 | 379 | |
ec90a194 PM |
380 | void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, |
381 | struct rcu_synchronize *rs_array) | |
2c42818e | 382 | { |
ec90a194 | 383 | int i; |
68ab0b42 | 384 | int j; |
ec90a194 | 385 | |
06462efc | 386 | /* Initialize and register callbacks for each crcu_array element. */ |
ec90a194 PM |
387 | for (i = 0; i < n; i++) { |
388 | if (checktiny && | |
309ba859 | 389 | (crcu_array[i] == call_rcu)) { |
ec90a194 PM |
390 | might_sleep(); |
391 | continue; | |
392 | } | |
393 | init_rcu_head_on_stack(&rs_array[i].head); | |
394 | init_completion(&rs_array[i].completion); | |
68ab0b42 PM |
395 | for (j = 0; j < i; j++) |
396 | if (crcu_array[j] == crcu_array[i]) | |
397 | break; | |
398 | if (j == i) | |
399 | (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); | |
ec90a194 PM |
400 | } |
401 | ||
402 | /* Wait for all callbacks to be invoked. */ | |
403 | for (i = 0; i < n; i++) { | |
404 | if (checktiny && | |
309ba859 | 405 | (crcu_array[i] == call_rcu)) |
ec90a194 | 406 | continue; |
68ab0b42 PM |
407 | for (j = 0; j < i; j++) |
408 | if (crcu_array[j] == crcu_array[i]) | |
409 | break; | |
410 | if (j == i) | |
411 | wait_for_completion(&rs_array[i].completion); | |
ec90a194 PM |
412 | destroy_rcu_head_on_stack(&rs_array[i].head); |
413 | } | |
2c42818e | 414 | } |
ec90a194 | 415 | EXPORT_SYMBOL_GPL(__wait_rcu_gp); |
2c42818e | 416 | |
551d55a9 | 417 | #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD |
546a9d85 | 418 | void init_rcu_head(struct rcu_head *head) |
551d55a9 MD |
419 | { |
420 | debug_object_init(head, &rcuhead_debug_descr); | |
421 | } | |
156baec3 | 422 | EXPORT_SYMBOL_GPL(init_rcu_head); |
551d55a9 | 423 | |
546a9d85 | 424 | void destroy_rcu_head(struct rcu_head *head) |
551d55a9 MD |
425 | { |
426 | debug_object_free(head, &rcuhead_debug_descr); | |
427 | } | |
156baec3 | 428 | EXPORT_SYMBOL_GPL(destroy_rcu_head); |
551d55a9 | 429 | |
b9fdac7f | 430 | static bool rcuhead_is_static_object(void *addr) |
551d55a9 | 431 | { |
b9fdac7f | 432 | return true; |
551d55a9 MD |
433 | } |
434 | ||
435 | /** | |
436 | * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects | |
437 | * @head: pointer to rcu_head structure to be initialized | |
438 | * | |
439 | * This function informs debugobjects of a new rcu_head structure that | |
440 | * has been allocated as an auto variable on the stack. This function | |
441 | * is not required for rcu_head structures that are statically defined or | |
442 | * that are dynamically allocated on the heap. This function has no | |
443 | * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
444 | */ | |
445 | void init_rcu_head_on_stack(struct rcu_head *head) | |
446 | { | |
447 | debug_object_init_on_stack(head, &rcuhead_debug_descr); | |
448 | } | |
449 | EXPORT_SYMBOL_GPL(init_rcu_head_on_stack); | |
450 | ||
451 | /** | |
452 | * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects | |
453 | * @head: pointer to rcu_head structure to be initialized | |
454 | * | |
455 | * This function informs debugobjects that an on-stack rcu_head structure | |
456 | * is about to go out of scope. As with init_rcu_head_on_stack(), this | |
457 | * function is not required for rcu_head structures that are statically | |
458 | * defined or that are dynamically allocated on the heap. Also as with | |
459 | * init_rcu_head_on_stack(), this function has no effect for | |
460 | * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
461 | */ | |
462 | void destroy_rcu_head_on_stack(struct rcu_head *head) | |
463 | { | |
464 | debug_object_free(head, &rcuhead_debug_descr); | |
465 | } | |
466 | EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); | |
467 | ||
468 | struct debug_obj_descr rcuhead_debug_descr = { | |
469 | .name = "rcu_head", | |
b9fdac7f | 470 | .is_static_object = rcuhead_is_static_object, |
551d55a9 MD |
471 | }; |
472 | EXPORT_SYMBOL_GPL(rcuhead_debug_descr); | |
473 | #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ | |
91afaf30 | 474 | |
b3e627d3 | 475 | #if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE) |
e66c33d5 | 476 | void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, |
52494535 PM |
477 | unsigned long secs, |
478 | unsigned long c_old, unsigned long c) | |
91afaf30 | 479 | { |
52494535 | 480 | trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); |
91afaf30 PM |
481 | } |
482 | EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); | |
483 | #else | |
52494535 PM |
484 | #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ |
485 | do { } while (0) | |
91afaf30 | 486 | #endif |
6bfc09e2 | 487 | |
c682db55 PM |
488 | #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) |
489 | /* Get rcutorture access to sched_setaffinity(). */ | |
490 | long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask) | |
491 | { | |
492 | int ret; | |
493 | ||
494 | ret = sched_setaffinity(pid, in_mask); | |
495 | WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret); | |
496 | return ret; | |
497 | } | |
498 | EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity); | |
499 | #endif | |
500 | ||
6bfc09e2 | 501 | #ifdef CONFIG_RCU_STALL_COMMON |
cdc694b2 PM |
502 | int rcu_cpu_stall_ftrace_dump __read_mostly; |
503 | module_param(rcu_cpu_stall_ftrace_dump, int, 0644); | |
58c53360 | 504 | int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings. |
f22ce091 | 505 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); |
6bfc09e2 | 506 | module_param(rcu_cpu_stall_suppress, int, 0644); |
10462d6f | 507 | int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; |
6bfc09e2 | 508 | module_param(rcu_cpu_stall_timeout, int, 0644); |
6bfc09e2 | 509 | #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ |
8315f422 | 510 | |
58c53360 PM |
511 | // Suppress boot-time RCU CPU stall warnings and rcutorture writer stall |
512 | // warnings. Also used by rcutorture even if stall warnings are excluded. | |
513 | int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls. | |
514 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot); | |
515 | module_param(rcu_cpu_stall_suppress_at_boot, int, 0444); | |
516 | ||
aa23c6fb PK |
517 | #ifdef CONFIG_PROVE_RCU |
518 | ||
519 | /* | |
72ce30dd | 520 | * Early boot self test parameters. |
aa23c6fb PK |
521 | */ |
522 | static bool rcu_self_test; | |
aa23c6fb | 523 | module_param(rcu_self_test, bool, 0444); |
aa23c6fb PK |
524 | |
525 | static int rcu_self_test_counter; | |
526 | ||
527 | static void test_callback(struct rcu_head *r) | |
528 | { | |
529 | rcu_self_test_counter++; | |
530 | pr_info("RCU test callback executed %d\n", rcu_self_test_counter); | |
531 | } | |
532 | ||
e0fcba9a PM |
533 | DEFINE_STATIC_SRCU(early_srcu); |
534 | ||
a35d1690 BP |
535 | struct early_boot_kfree_rcu { |
536 | struct rcu_head rh; | |
537 | }; | |
538 | ||
aa23c6fb PK |
539 | static void early_boot_test_call_rcu(void) |
540 | { | |
541 | static struct rcu_head head; | |
e0fcba9a | 542 | static struct rcu_head shead; |
a35d1690 | 543 | struct early_boot_kfree_rcu *rhp; |
aa23c6fb PK |
544 | |
545 | call_rcu(&head, test_callback); | |
e0fcba9a PM |
546 | if (IS_ENABLED(CONFIG_SRCU)) |
547 | call_srcu(&early_srcu, &shead, test_callback); | |
a35d1690 BP |
548 | rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); |
549 | if (!WARN_ON_ONCE(!rhp)) | |
550 | kfree_rcu(rhp, rh); | |
aa23c6fb PK |
551 | } |
552 | ||
553 | void rcu_early_boot_tests(void) | |
554 | { | |
555 | pr_info("Running RCU self tests\n"); | |
556 | ||
557 | if (rcu_self_test) | |
558 | early_boot_test_call_rcu(); | |
52d7e48b | 559 | rcu_test_sync_prims(); |
aa23c6fb PK |
560 | } |
561 | ||
562 | static int rcu_verify_early_boot_tests(void) | |
563 | { | |
564 | int ret = 0; | |
565 | int early_boot_test_counter = 0; | |
566 | ||
567 | if (rcu_self_test) { | |
568 | early_boot_test_counter++; | |
569 | rcu_barrier(); | |
e0fcba9a PM |
570 | if (IS_ENABLED(CONFIG_SRCU)) { |
571 | early_boot_test_counter++; | |
572 | srcu_barrier(&early_srcu); | |
573 | } | |
aa23c6fb | 574 | } |
aa23c6fb PK |
575 | if (rcu_self_test_counter != early_boot_test_counter) { |
576 | WARN_ON(1); | |
577 | ret = -1; | |
578 | } | |
579 | ||
580 | return ret; | |
581 | } | |
582 | late_initcall(rcu_verify_early_boot_tests); | |
583 | #else | |
584 | void rcu_early_boot_tests(void) {} | |
585 | #endif /* CONFIG_PROVE_RCU */ | |
59d80fd8 | 586 | |
eacd6f04 PM |
587 | #include "tasks.h" |
588 | ||
59d80fd8 PM |
589 | #ifndef CONFIG_TINY_RCU |
590 | ||
591 | /* | |
592 | * Print any significant non-default boot-time settings. | |
593 | */ | |
594 | void __init rcupdate_announce_bootup_oddness(void) | |
595 | { | |
596 | if (rcu_normal) | |
597 | pr_info("\tNo expedited grace period (rcu_normal).\n"); | |
598 | else if (rcu_normal_after_boot) | |
599 | pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n"); | |
600 | else if (rcu_expedited) | |
601 | pr_info("\tAll grace periods are expedited (rcu_expedited).\n"); | |
602 | if (rcu_cpu_stall_suppress) | |
603 | pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n"); | |
604 | if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT) | |
605 | pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout); | |
606 | rcu_tasks_bootup_oddness(); | |
607 | } | |
608 | ||
609 | #endif /* #ifndef CONFIG_TINY_RCU */ |