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1da177e4 LT |
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
87de1cfd PM |
15 | * along with this program; if not, you can access it online at |
16 | * http://www.gnu.org/licenses/gpl-2.0.html. | |
1da177e4 | 17 | * |
01c1c660 | 18 | * Copyright IBM Corporation, 2001 |
1da177e4 LT |
19 | * |
20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> | |
21 | * Manfred Spraul <manfred@colorfullife.com> | |
a71fca58 | 22 | * |
1da177e4 LT |
23 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
24 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. | |
25 | * Papers: | |
26 | * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf | |
27 | * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) | |
28 | * | |
29 | * For detailed explanation of Read-Copy Update mechanism see - | |
a71fca58 | 30 | * http://lse.sourceforge.net/locking/rcupdate.html |
1da177e4 LT |
31 | * |
32 | */ | |
33 | #include <linux/types.h> | |
34 | #include <linux/kernel.h> | |
35 | #include <linux/init.h> | |
36 | #include <linux/spinlock.h> | |
37 | #include <linux/smp.h> | |
38 | #include <linux/interrupt.h> | |
3f07c014 | 39 | #include <linux/sched/signal.h> |
b17b0153 | 40 | #include <linux/sched/debug.h> |
60063497 | 41 | #include <linux/atomic.h> |
1da177e4 | 42 | #include <linux/bitops.h> |
1da177e4 LT |
43 | #include <linux/percpu.h> |
44 | #include <linux/notifier.h> | |
1da177e4 | 45 | #include <linux/cpu.h> |
9331b315 | 46 | #include <linux/mutex.h> |
9984de1a | 47 | #include <linux/export.h> |
e3818b8d | 48 | #include <linux/hardirq.h> |
e3ebfb96 | 49 | #include <linux/delay.h> |
e77b7041 | 50 | #include <linux/moduleparam.h> |
8315f422 | 51 | #include <linux/kthread.h> |
4ff475ed | 52 | #include <linux/tick.h> |
f9411ebe | 53 | #include <linux/rcupdate_wait.h> |
78634061 | 54 | #include <linux/sched/isolation.h> |
6405b1af | 55 | #include <linux/kprobes.h> |
1da177e4 | 56 | |
29c00b4a | 57 | #define CREATE_TRACE_POINTS |
29c00b4a PM |
58 | |
59 | #include "rcu.h" | |
60 | ||
4102adab PM |
61 | #ifdef MODULE_PARAM_PREFIX |
62 | #undef MODULE_PARAM_PREFIX | |
63 | #endif | |
64 | #define MODULE_PARAM_PREFIX "rcupdate." | |
65 | ||
79cfea02 | 66 | #ifndef CONFIG_TINY_RCU |
3caec62f | 67 | extern int rcu_expedited; /* from sysctl */ |
3705b88d | 68 | module_param(rcu_expedited, int, 0); |
3caec62f | 69 | extern int rcu_normal; /* from sysctl */ |
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 DV |
76 | /** |
77 | * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? | |
78 | * | |
79 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an | |
80 | * RCU-sched read-side critical section. In absence of | |
81 | * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side | |
82 | * critical section unless it can prove otherwise. Note that disabling | |
83 | * of preemption (including disabling irqs) counts as an RCU-sched | |
84 | * read-side critical section. This is useful for debug checks in functions | |
85 | * that required that they be called within an RCU-sched read-side | |
86 | * critical section. | |
87 | * | |
88 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot | |
89 | * and while lockdep is disabled. | |
90 | * | |
91 | * Note that if the CPU is in the idle loop from an RCU point of | |
92 | * view (ie: that we are in the section between rcu_idle_enter() and | |
93 | * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU | |
94 | * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs | |
95 | * that are in such a section, considering these as in extended quiescent | |
96 | * state, so such a CPU is effectively never in an RCU read-side critical | |
97 | * section regardless of what RCU primitives it invokes. This state of | |
98 | * affairs is required --- we need to keep an RCU-free window in idle | |
99 | * where the CPU may possibly enter into low power mode. This way we can | |
100 | * notice an extended quiescent state to other CPUs that started a grace | |
101 | * period. Otherwise we would delay any grace period as long as we run in | |
102 | * the idle task. | |
103 | * | |
104 | * Similarly, we avoid claiming an SRCU read lock held if the current | |
105 | * CPU is offline. | |
106 | */ | |
107 | int rcu_read_lock_sched_held(void) | |
108 | { | |
109 | int lockdep_opinion = 0; | |
110 | ||
111 | if (!debug_lockdep_rcu_enabled()) | |
112 | return 1; | |
113 | if (!rcu_is_watching()) | |
114 | return 0; | |
115 | if (!rcu_lockdep_current_cpu_online()) | |
116 | return 0; | |
117 | if (debug_locks) | |
118 | lockdep_opinion = lock_is_held(&rcu_sched_lock_map); | |
293e2421 | 119 | return lockdep_opinion || !preemptible(); |
d5671f6b DV |
120 | } |
121 | EXPORT_SYMBOL(rcu_read_lock_sched_held); | |
122 | #endif | |
123 | ||
0d39482c PM |
124 | #ifndef CONFIG_TINY_RCU |
125 | ||
5a9be7c6 PM |
126 | /* |
127 | * Should expedited grace-period primitives always fall back to their | |
128 | * non-expedited counterparts? Intended for use within RCU. Note | |
129 | * that if the user specifies both rcu_expedited and rcu_normal, then | |
52d7e48b | 130 | * rcu_normal wins. (Except during the time period during boot from |
900b1028 | 131 | * when the first task is spawned until the rcu_set_runtime_mode() |
52d7e48b | 132 | * core_initcall() is invoked, at which point everything is expedited.) |
5a9be7c6 PM |
133 | */ |
134 | bool rcu_gp_is_normal(void) | |
135 | { | |
52d7e48b PM |
136 | return READ_ONCE(rcu_normal) && |
137 | rcu_scheduler_active != RCU_SCHEDULER_INIT; | |
5a9be7c6 | 138 | } |
4f2a848c | 139 | EXPORT_SYMBOL_GPL(rcu_gp_is_normal); |
5a9be7c6 | 140 | |
7c6094db | 141 | static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); |
0d39482c PM |
142 | |
143 | /* | |
144 | * Should normal grace-period primitives be expedited? Intended for | |
145 | * use within RCU. Note that this function takes the rcu_expedited | |
52d7e48b PM |
146 | * sysfs/boot variable and rcu_scheduler_active into account as well |
147 | * as the rcu_expedite_gp() nesting. So looping on rcu_unexpedite_gp() | |
148 | * until rcu_gp_is_expedited() returns false is a -really- bad idea. | |
0d39482c PM |
149 | */ |
150 | bool rcu_gp_is_expedited(void) | |
151 | { | |
52d7e48b PM |
152 | return rcu_expedited || atomic_read(&rcu_expedited_nesting) || |
153 | rcu_scheduler_active == RCU_SCHEDULER_INIT; | |
0d39482c PM |
154 | } |
155 | EXPORT_SYMBOL_GPL(rcu_gp_is_expedited); | |
156 | ||
157 | /** | |
158 | * rcu_expedite_gp - Expedite future RCU grace periods | |
159 | * | |
160 | * After a call to this function, future calls to synchronize_rcu() and | |
161 | * friends act as the corresponding synchronize_rcu_expedited() function | |
162 | * had instead been called. | |
163 | */ | |
164 | void rcu_expedite_gp(void) | |
165 | { | |
166 | atomic_inc(&rcu_expedited_nesting); | |
167 | } | |
168 | EXPORT_SYMBOL_GPL(rcu_expedite_gp); | |
169 | ||
170 | /** | |
171 | * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation | |
172 | * | |
173 | * Undo a prior call to rcu_expedite_gp(). If all prior calls to | |
174 | * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(), | |
175 | * and if the rcu_expedited sysfs/boot parameter is not set, then all | |
176 | * subsequent calls to synchronize_rcu() and friends will return to | |
177 | * their normal non-expedited behavior. | |
178 | */ | |
179 | void rcu_unexpedite_gp(void) | |
180 | { | |
181 | atomic_dec(&rcu_expedited_nesting); | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); | |
184 | ||
ee42571f PM |
185 | /* |
186 | * Inform RCU of the end of the in-kernel boot sequence. | |
187 | */ | |
188 | void rcu_end_inkernel_boot(void) | |
189 | { | |
7c6094db | 190 | rcu_unexpedite_gp(); |
3e42ec1a PM |
191 | if (rcu_normal_after_boot) |
192 | WRITE_ONCE(rcu_normal, 1); | |
ee42571f | 193 | } |
0d39482c | 194 | |
79cfea02 PM |
195 | #endif /* #ifndef CONFIG_TINY_RCU */ |
196 | ||
900b1028 PM |
197 | /* |
198 | * Test each non-SRCU synchronous grace-period wait API. This is | |
199 | * useful just after a change in mode for these primitives, and | |
200 | * during early boot. | |
201 | */ | |
202 | void rcu_test_sync_prims(void) | |
203 | { | |
204 | if (!IS_ENABLED(CONFIG_PROVE_RCU)) | |
205 | return; | |
206 | synchronize_rcu(); | |
207 | synchronize_rcu_bh(); | |
208 | synchronize_sched(); | |
209 | synchronize_rcu_expedited(); | |
210 | synchronize_rcu_bh_expedited(); | |
211 | synchronize_sched_expedited(); | |
212 | } | |
213 | ||
214 | #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) | |
215 | ||
216 | /* | |
217 | * Switch to run-time mode once RCU has fully initialized. | |
218 | */ | |
219 | static int __init rcu_set_runtime_mode(void) | |
220 | { | |
221 | rcu_test_sync_prims(); | |
222 | rcu_scheduler_active = RCU_SCHEDULER_RUNNING; | |
223 | rcu_test_sync_prims(); | |
224 | return 0; | |
225 | } | |
226 | core_initcall(rcu_set_runtime_mode); | |
227 | ||
228 | #endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */ | |
229 | ||
9dd8fb16 PM |
230 | #ifdef CONFIG_PREEMPT_RCU |
231 | ||
2a3fa843 PM |
232 | /* |
233 | * Preemptible RCU implementation for rcu_read_lock(). | |
234 | * Just increment ->rcu_read_lock_nesting, shared state will be updated | |
235 | * if we block. | |
236 | */ | |
237 | void __rcu_read_lock(void) | |
238 | { | |
239 | current->rcu_read_lock_nesting++; | |
240 | barrier(); /* critical section after entry code. */ | |
241 | } | |
242 | EXPORT_SYMBOL_GPL(__rcu_read_lock); | |
243 | ||
244 | /* | |
245 | * Preemptible RCU implementation for rcu_read_unlock(). | |
246 | * Decrement ->rcu_read_lock_nesting. If the result is zero (outermost | |
247 | * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then | |
248 | * invoke rcu_read_unlock_special() to clean up after a context switch | |
249 | * in an RCU read-side critical section and other special cases. | |
250 | */ | |
251 | void __rcu_read_unlock(void) | |
252 | { | |
253 | struct task_struct *t = current; | |
254 | ||
255 | if (t->rcu_read_lock_nesting != 1) { | |
256 | --t->rcu_read_lock_nesting; | |
257 | } else { | |
258 | barrier(); /* critical section before exit code. */ | |
259 | t->rcu_read_lock_nesting = INT_MIN; | |
260 | barrier(); /* assign before ->rcu_read_unlock_special load */ | |
7d0ae808 | 261 | if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s))) |
2a3fa843 PM |
262 | rcu_read_unlock_special(t); |
263 | barrier(); /* ->rcu_read_unlock_special load before assign */ | |
264 | t->rcu_read_lock_nesting = 0; | |
265 | } | |
266 | #ifdef CONFIG_PROVE_LOCKING | |
267 | { | |
7d0ae808 | 268 | int rrln = READ_ONCE(t->rcu_read_lock_nesting); |
2a3fa843 PM |
269 | |
270 | WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2); | |
271 | } | |
272 | #endif /* #ifdef CONFIG_PROVE_LOCKING */ | |
273 | } | |
274 | EXPORT_SYMBOL_GPL(__rcu_read_unlock); | |
275 | ||
2439b696 | 276 | #endif /* #ifdef CONFIG_PREEMPT_RCU */ |
9dd8fb16 | 277 | |
162cc279 PM |
278 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
279 | static struct lock_class_key rcu_lock_key; | |
280 | struct lockdep_map rcu_lock_map = | |
281 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); | |
282 | EXPORT_SYMBOL_GPL(rcu_lock_map); | |
632ee200 PM |
283 | |
284 | static struct lock_class_key rcu_bh_lock_key; | |
285 | struct lockdep_map rcu_bh_lock_map = | |
286 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key); | |
287 | EXPORT_SYMBOL_GPL(rcu_bh_lock_map); | |
288 | ||
289 | static struct lock_class_key rcu_sched_lock_key; | |
290 | struct lockdep_map rcu_sched_lock_map = | |
291 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key); | |
292 | EXPORT_SYMBOL_GPL(rcu_sched_lock_map); | |
e3818b8d | 293 | |
24ef659a PM |
294 | static struct lock_class_key rcu_callback_key; |
295 | struct lockdep_map rcu_callback_map = | |
296 | STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key); | |
297 | EXPORT_SYMBOL_GPL(rcu_callback_map); | |
298 | ||
a0a5a056 | 299 | int notrace debug_lockdep_rcu_enabled(void) |
bc293d62 | 300 | { |
52d7e48b | 301 | return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks && |
bc293d62 PM |
302 | current->lockdep_recursion == 0; |
303 | } | |
304 | EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); | |
6405b1af | 305 | NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled); |
bc293d62 | 306 | |
85b39d30 ON |
307 | /** |
308 | * rcu_read_lock_held() - might we be in RCU read-side critical section? | |
309 | * | |
310 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU | |
311 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
312 | * this assumes we are in an RCU read-side critical section unless it can | |
313 | * prove otherwise. This is useful for debug checks in functions that | |
314 | * require that they be called within an RCU read-side critical section. | |
315 | * | |
316 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot | |
317 | * and while lockdep is disabled. | |
318 | * | |
319 | * Note that rcu_read_lock() and the matching rcu_read_unlock() must | |
320 | * occur in the same context, for example, it is illegal to invoke | |
321 | * rcu_read_unlock() in process context if the matching rcu_read_lock() | |
322 | * was invoked from within an irq handler. | |
323 | * | |
324 | * Note that rcu_read_lock() is disallowed if the CPU is either idle or | |
325 | * offline from an RCU perspective, so check for those as well. | |
326 | */ | |
327 | int rcu_read_lock_held(void) | |
328 | { | |
329 | if (!debug_lockdep_rcu_enabled()) | |
330 | return 1; | |
331 | if (!rcu_is_watching()) | |
332 | return 0; | |
333 | if (!rcu_lockdep_current_cpu_online()) | |
334 | return 0; | |
335 | return lock_is_held(&rcu_lock_map); | |
336 | } | |
337 | EXPORT_SYMBOL_GPL(rcu_read_lock_held); | |
338 | ||
e3818b8d | 339 | /** |
ca5ecddf | 340 | * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section? |
e3818b8d PM |
341 | * |
342 | * Check for bottom half being disabled, which covers both the | |
343 | * CONFIG_PROVE_RCU and not cases. Note that if someone uses | |
344 | * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) | |
ca5ecddf PM |
345 | * will show the situation. This is useful for debug checks in functions |
346 | * that require that they be called within an RCU read-side critical | |
347 | * section. | |
e3818b8d PM |
348 | * |
349 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. | |
c0d6d01b PM |
350 | * |
351 | * Note that rcu_read_lock() is disallowed if the CPU is either idle or | |
352 | * offline from an RCU perspective, so check for those as well. | |
e3818b8d PM |
353 | */ |
354 | int rcu_read_lock_bh_held(void) | |
355 | { | |
356 | if (!debug_lockdep_rcu_enabled()) | |
357 | return 1; | |
5c173eb8 | 358 | if (!rcu_is_watching()) |
e6b80a3b | 359 | return 0; |
c0d6d01b PM |
360 | if (!rcu_lockdep_current_cpu_online()) |
361 | return 0; | |
773e3f93 | 362 | return in_softirq() || irqs_disabled(); |
e3818b8d PM |
363 | } |
364 | EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); | |
365 | ||
366 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
367 | ||
ee376dbd PM |
368 | /** |
369 | * wakeme_after_rcu() - Callback function to awaken a task after grace period | |
370 | * @head: Pointer to rcu_head member within rcu_synchronize structure | |
371 | * | |
372 | * Awaken the corresponding task now that a grace period has elapsed. | |
fbf6bfca | 373 | */ |
ee376dbd | 374 | void wakeme_after_rcu(struct rcu_head *head) |
21a1ea9e | 375 | { |
01c1c660 PM |
376 | struct rcu_synchronize *rcu; |
377 | ||
378 | rcu = container_of(head, struct rcu_synchronize, head); | |
379 | complete(&rcu->completion); | |
21a1ea9e | 380 | } |
ec90a194 | 381 | EXPORT_SYMBOL_GPL(wakeme_after_rcu); |
ee84b824 | 382 | |
ec90a194 PM |
383 | void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, |
384 | struct rcu_synchronize *rs_array) | |
2c42818e | 385 | { |
ec90a194 | 386 | int i; |
68ab0b42 | 387 | int j; |
ec90a194 PM |
388 | |
389 | /* Initialize and register callbacks for each flavor specified. */ | |
390 | for (i = 0; i < n; i++) { | |
391 | if (checktiny && | |
392 | (crcu_array[i] == call_rcu || | |
393 | crcu_array[i] == call_rcu_bh)) { | |
394 | might_sleep(); | |
395 | continue; | |
396 | } | |
397 | init_rcu_head_on_stack(&rs_array[i].head); | |
398 | init_completion(&rs_array[i].completion); | |
68ab0b42 PM |
399 | for (j = 0; j < i; j++) |
400 | if (crcu_array[j] == crcu_array[i]) | |
401 | break; | |
402 | if (j == i) | |
403 | (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); | |
ec90a194 PM |
404 | } |
405 | ||
406 | /* Wait for all callbacks to be invoked. */ | |
407 | for (i = 0; i < n; i++) { | |
408 | if (checktiny && | |
409 | (crcu_array[i] == call_rcu || | |
410 | crcu_array[i] == call_rcu_bh)) | |
411 | continue; | |
68ab0b42 PM |
412 | for (j = 0; j < i; j++) |
413 | if (crcu_array[j] == crcu_array[i]) | |
414 | break; | |
415 | if (j == i) | |
416 | wait_for_completion(&rs_array[i].completion); | |
ec90a194 PM |
417 | destroy_rcu_head_on_stack(&rs_array[i].head); |
418 | } | |
2c42818e | 419 | } |
ec90a194 | 420 | EXPORT_SYMBOL_GPL(__wait_rcu_gp); |
2c42818e | 421 | |
551d55a9 | 422 | #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD |
546a9d85 | 423 | void init_rcu_head(struct rcu_head *head) |
551d55a9 MD |
424 | { |
425 | debug_object_init(head, &rcuhead_debug_descr); | |
426 | } | |
1d276790 | 427 | EXPORT_SYMBOL_GPL(init_rcu_head); |
551d55a9 | 428 | |
546a9d85 | 429 | void destroy_rcu_head(struct rcu_head *head) |
551d55a9 MD |
430 | { |
431 | debug_object_free(head, &rcuhead_debug_descr); | |
432 | } | |
1d276790 | 433 | EXPORT_SYMBOL_GPL(destroy_rcu_head); |
551d55a9 | 434 | |
b9fdac7f | 435 | static bool rcuhead_is_static_object(void *addr) |
551d55a9 | 436 | { |
b9fdac7f | 437 | return true; |
551d55a9 MD |
438 | } |
439 | ||
440 | /** | |
441 | * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects | |
442 | * @head: pointer to rcu_head structure to be initialized | |
443 | * | |
444 | * This function informs debugobjects of a new rcu_head structure that | |
445 | * has been allocated as an auto variable on the stack. This function | |
446 | * is not required for rcu_head structures that are statically defined or | |
447 | * that are dynamically allocated on the heap. This function has no | |
448 | * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
449 | */ | |
450 | void init_rcu_head_on_stack(struct rcu_head *head) | |
451 | { | |
452 | debug_object_init_on_stack(head, &rcuhead_debug_descr); | |
453 | } | |
454 | EXPORT_SYMBOL_GPL(init_rcu_head_on_stack); | |
455 | ||
456 | /** | |
457 | * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects | |
458 | * @head: pointer to rcu_head structure to be initialized | |
459 | * | |
460 | * This function informs debugobjects that an on-stack rcu_head structure | |
461 | * is about to go out of scope. As with init_rcu_head_on_stack(), this | |
462 | * function is not required for rcu_head structures that are statically | |
463 | * defined or that are dynamically allocated on the heap. Also as with | |
464 | * init_rcu_head_on_stack(), this function has no effect for | |
465 | * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds. | |
466 | */ | |
467 | void destroy_rcu_head_on_stack(struct rcu_head *head) | |
468 | { | |
469 | debug_object_free(head, &rcuhead_debug_descr); | |
470 | } | |
471 | EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); | |
472 | ||
473 | struct debug_obj_descr rcuhead_debug_descr = { | |
474 | .name = "rcu_head", | |
b9fdac7f | 475 | .is_static_object = rcuhead_is_static_object, |
551d55a9 MD |
476 | }; |
477 | EXPORT_SYMBOL_GPL(rcuhead_debug_descr); | |
478 | #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ | |
91afaf30 | 479 | |
28f6569a | 480 | #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE) |
e66c33d5 | 481 | void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, |
52494535 PM |
482 | unsigned long secs, |
483 | unsigned long c_old, unsigned long c) | |
91afaf30 | 484 | { |
52494535 | 485 | trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c); |
91afaf30 PM |
486 | } |
487 | EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); | |
488 | #else | |
52494535 PM |
489 | #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ |
490 | do { } while (0) | |
91afaf30 | 491 | #endif |
6bfc09e2 PM |
492 | |
493 | #ifdef CONFIG_RCU_STALL_COMMON | |
494 | ||
495 | #ifdef CONFIG_PROVE_RCU | |
496 | #define RCU_STALL_DELAY_DELTA (5 * HZ) | |
497 | #else | |
498 | #define RCU_STALL_DELAY_DELTA 0 | |
499 | #endif | |
500 | ||
501 | int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ | |
f22ce091 | 502 | EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); |
01896f7e | 503 | static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; |
6bfc09e2 PM |
504 | |
505 | module_param(rcu_cpu_stall_suppress, int, 0644); | |
506 | module_param(rcu_cpu_stall_timeout, int, 0644); | |
507 | ||
508 | int rcu_jiffies_till_stall_check(void) | |
509 | { | |
7d0ae808 | 510 | int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout); |
6bfc09e2 PM |
511 | |
512 | /* | |
513 | * Limit check must be consistent with the Kconfig limits | |
514 | * for CONFIG_RCU_CPU_STALL_TIMEOUT. | |
515 | */ | |
516 | if (till_stall_check < 3) { | |
7d0ae808 | 517 | WRITE_ONCE(rcu_cpu_stall_timeout, 3); |
6bfc09e2 PM |
518 | till_stall_check = 3; |
519 | } else if (till_stall_check > 300) { | |
7d0ae808 | 520 | WRITE_ONCE(rcu_cpu_stall_timeout, 300); |
6bfc09e2 PM |
521 | till_stall_check = 300; |
522 | } | |
523 | return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; | |
524 | } | |
525 | ||
61f38db3 RR |
526 | void rcu_sysrq_start(void) |
527 | { | |
528 | if (!rcu_cpu_stall_suppress) | |
529 | rcu_cpu_stall_suppress = 2; | |
530 | } | |
531 | ||
532 | void rcu_sysrq_end(void) | |
533 | { | |
534 | if (rcu_cpu_stall_suppress == 2) | |
535 | rcu_cpu_stall_suppress = 0; | |
536 | } | |
537 | ||
6bfc09e2 PM |
538 | static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) |
539 | { | |
540 | rcu_cpu_stall_suppress = 1; | |
541 | return NOTIFY_DONE; | |
542 | } | |
543 | ||
544 | static struct notifier_block rcu_panic_block = { | |
545 | .notifier_call = rcu_panic, | |
546 | }; | |
547 | ||
548 | static int __init check_cpu_stall_init(void) | |
549 | { | |
550 | atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); | |
551 | return 0; | |
552 | } | |
553 | early_initcall(check_cpu_stall_init); | |
554 | ||
555 | #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ | |
8315f422 PM |
556 | |
557 | #ifdef CONFIG_TASKS_RCU | |
558 | ||
559 | /* | |
560 | * Simple variant of RCU whose quiescent states are voluntary context switch, | |
561 | * user-space execution, and idle. As such, grace periods can take one good | |
562 | * long time. There are no read-side primitives similar to rcu_read_lock() | |
563 | * and rcu_read_unlock() because this implementation is intended to get | |
564 | * the system into a safe state for some of the manipulations involved in | |
565 | * tracing and the like. Finally, this implementation does not support | |
566 | * high call_rcu_tasks() rates from multiple CPUs. If this is required, | |
567 | * per-CPU callback lists will be needed. | |
568 | */ | |
569 | ||
570 | /* Global list of callbacks and associated lock. */ | |
571 | static struct rcu_head *rcu_tasks_cbs_head; | |
572 | static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head; | |
c7b24d2b | 573 | static DECLARE_WAIT_QUEUE_HEAD(rcu_tasks_cbs_wq); |
8315f422 PM |
574 | static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock); |
575 | ||
3f95aa81 | 576 | /* Track exiting tasks in order to allow them to be waited for. */ |
ccdd29ff | 577 | DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu); |
3f95aa81 PM |
578 | |
579 | /* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */ | |
59d80fd8 PM |
580 | #define RCU_TASK_STALL_TIMEOUT (HZ * 60 * 10) |
581 | static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT; | |
3f95aa81 PM |
582 | module_param(rcu_task_stall_timeout, int, 0644); |
583 | ||
4929c913 | 584 | static struct task_struct *rcu_tasks_kthread_ptr; |
84a8f446 | 585 | |
a68a2bb2 PM |
586 | /** |
587 | * call_rcu_tasks() - Queue an RCU for invocation task-based grace period | |
588 | * @rhp: structure to be used for queueing the RCU updates. | |
589 | * @func: actual callback function to be invoked after the grace period | |
590 | * | |
591 | * The callback function will be invoked some time after a full grace | |
592 | * period elapses, in other words after all currently executing RCU | |
593 | * read-side critical sections have completed. call_rcu_tasks() assumes | |
594 | * that the read-side critical sections end at a voluntary context | |
595 | * switch (not a preemption!), entry into idle, or transition to usermode | |
596 | * execution. As such, there are no read-side primitives analogous to | |
597 | * rcu_read_lock() and rcu_read_unlock() because this primitive is intended | |
598 | * to determine that all tasks have passed through a safe state, not so | |
599 | * much for data-strcuture synchronization. | |
600 | * | |
601 | * See the description of call_rcu() for more detailed information on | |
602 | * memory ordering guarantees. | |
84a8f446 | 603 | */ |
b6a4ae76 | 604 | void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func) |
8315f422 PM |
605 | { |
606 | unsigned long flags; | |
c7b24d2b | 607 | bool needwake; |
8315f422 PM |
608 | |
609 | rhp->next = NULL; | |
610 | rhp->func = func; | |
611 | raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags); | |
c7b24d2b | 612 | needwake = !rcu_tasks_cbs_head; |
8315f422 PM |
613 | *rcu_tasks_cbs_tail = rhp; |
614 | rcu_tasks_cbs_tail = &rhp->next; | |
615 | raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags); | |
4929c913 | 616 | /* We can't create the thread unless interrupts are enabled. */ |
c63eb17f | 617 | if (needwake && READ_ONCE(rcu_tasks_kthread_ptr)) |
c7b24d2b | 618 | wake_up(&rcu_tasks_cbs_wq); |
8315f422 PM |
619 | } |
620 | EXPORT_SYMBOL_GPL(call_rcu_tasks); | |
621 | ||
53c6d4ed PM |
622 | /** |
623 | * synchronize_rcu_tasks - wait until an rcu-tasks grace period has elapsed. | |
624 | * | |
625 | * Control will return to the caller some time after a full rcu-tasks | |
626 | * grace period has elapsed, in other words after all currently | |
627 | * executing rcu-tasks read-side critical sections have elapsed. These | |
628 | * read-side critical sections are delimited by calls to schedule(), | |
629 | * cond_resched_rcu_qs(), idle execution, userspace execution, calls | |
630 | * to synchronize_rcu_tasks(), and (in theory, anyway) cond_resched(). | |
631 | * | |
632 | * This is a very specialized primitive, intended only for a few uses in | |
633 | * tracing and other situations requiring manipulation of function | |
634 | * preambles and profiling hooks. The synchronize_rcu_tasks() function | |
635 | * is not (yet) intended for heavy use from multiple CPUs. | |
636 | * | |
637 | * Note that this guarantee implies further memory-ordering guarantees. | |
638 | * On systems with more than one CPU, when synchronize_rcu_tasks() returns, | |
639 | * each CPU is guaranteed to have executed a full memory barrier since the | |
640 | * end of its last RCU-tasks read-side critical section whose beginning | |
641 | * preceded the call to synchronize_rcu_tasks(). In addition, each CPU | |
642 | * having an RCU-tasks read-side critical section that extends beyond | |
643 | * the return from synchronize_rcu_tasks() is guaranteed to have executed | |
644 | * a full memory barrier after the beginning of synchronize_rcu_tasks() | |
645 | * and before the beginning of that RCU-tasks read-side critical section. | |
646 | * Note that these guarantees include CPUs that are offline, idle, or | |
647 | * executing in user mode, as well as CPUs that are executing in the kernel. | |
648 | * | |
649 | * Furthermore, if CPU A invoked synchronize_rcu_tasks(), which returned | |
650 | * to its caller on CPU B, then both CPU A and CPU B are guaranteed | |
651 | * to have executed a full memory barrier during the execution of | |
652 | * synchronize_rcu_tasks() -- even if CPU A and CPU B are the same CPU | |
653 | * (but again only if the system has more than one CPU). | |
654 | */ | |
655 | void synchronize_rcu_tasks(void) | |
656 | { | |
657 | /* Complain if the scheduler has not started. */ | |
52d7e48b | 658 | RCU_LOCKDEP_WARN(rcu_scheduler_active == RCU_SCHEDULER_INACTIVE, |
f78f5b90 | 659 | "synchronize_rcu_tasks called too soon"); |
53c6d4ed PM |
660 | |
661 | /* Wait for the grace period. */ | |
662 | wait_rcu_gp(call_rcu_tasks); | |
663 | } | |
06c2a923 | 664 | EXPORT_SYMBOL_GPL(synchronize_rcu_tasks); |
53c6d4ed PM |
665 | |
666 | /** | |
667 | * rcu_barrier_tasks - Wait for in-flight call_rcu_tasks() callbacks. | |
668 | * | |
669 | * Although the current implementation is guaranteed to wait, it is not | |
670 | * obligated to, for example, if there are no pending callbacks. | |
671 | */ | |
672 | void rcu_barrier_tasks(void) | |
673 | { | |
674 | /* There is only one callback queue, so this is easy. ;-) */ | |
675 | synchronize_rcu_tasks(); | |
676 | } | |
06c2a923 | 677 | EXPORT_SYMBOL_GPL(rcu_barrier_tasks); |
53c6d4ed | 678 | |
52db30ab PM |
679 | /* See if tasks are still holding out, complain if so. */ |
680 | static void check_holdout_task(struct task_struct *t, | |
681 | bool needreport, bool *firstreport) | |
8315f422 | 682 | { |
4ff475ed PM |
683 | int cpu; |
684 | ||
7d0ae808 PM |
685 | if (!READ_ONCE(t->rcu_tasks_holdout) || |
686 | t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) || | |
687 | !READ_ONCE(t->on_rq) || | |
176f8f7a PM |
688 | (IS_ENABLED(CONFIG_NO_HZ_FULL) && |
689 | !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) { | |
7d0ae808 | 690 | WRITE_ONCE(t->rcu_tasks_holdout, false); |
8f20a5e8 | 691 | list_del_init(&t->rcu_tasks_holdout_list); |
8315f422 | 692 | put_task_struct(t); |
52db30ab | 693 | return; |
8315f422 | 694 | } |
bcbfdd01 | 695 | rcu_request_urgent_qs_task(t); |
52db30ab PM |
696 | if (!needreport) |
697 | return; | |
698 | if (*firstreport) { | |
699 | pr_err("INFO: rcu_tasks detected stalls on tasks:\n"); | |
700 | *firstreport = false; | |
701 | } | |
4ff475ed PM |
702 | cpu = task_cpu(t); |
703 | pr_alert("%p: %c%c nvcsw: %lu/%lu holdout: %d idle_cpu: %d/%d\n", | |
704 | t, ".I"[is_idle_task(t)], | |
705 | "N."[cpu < 0 || !tick_nohz_full_cpu(cpu)], | |
706 | t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout, | |
707 | t->rcu_tasks_idle_cpu, cpu); | |
52db30ab | 708 | sched_show_task(t); |
8315f422 PM |
709 | } |
710 | ||
711 | /* RCU-tasks kthread that detects grace periods and invokes callbacks. */ | |
712 | static int __noreturn rcu_tasks_kthread(void *arg) | |
713 | { | |
714 | unsigned long flags; | |
715 | struct task_struct *g, *t; | |
52db30ab | 716 | unsigned long lastreport; |
8315f422 PM |
717 | struct rcu_head *list; |
718 | struct rcu_head *next; | |
719 | LIST_HEAD(rcu_tasks_holdouts); | |
720 | ||
60ced495 | 721 | /* Run on housekeeping CPUs by default. Sysadm can move if desired. */ |
de201559 | 722 | housekeeping_affine(current, HK_FLAG_RCU); |
8315f422 PM |
723 | |
724 | /* | |
725 | * Each pass through the following loop makes one check for | |
726 | * newly arrived callbacks, and, if there are some, waits for | |
727 | * one RCU-tasks grace period and then invokes the callbacks. | |
728 | * This loop is terminated by the system going down. ;-) | |
729 | */ | |
730 | for (;;) { | |
731 | ||
732 | /* Pick up any new callbacks. */ | |
733 | raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags); | |
734 | list = rcu_tasks_cbs_head; | |
735 | rcu_tasks_cbs_head = NULL; | |
736 | rcu_tasks_cbs_tail = &rcu_tasks_cbs_head; | |
737 | raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags); | |
738 | ||
739 | /* If there were none, wait a bit and start over. */ | |
740 | if (!list) { | |
c7b24d2b PM |
741 | wait_event_interruptible(rcu_tasks_cbs_wq, |
742 | rcu_tasks_cbs_head); | |
743 | if (!rcu_tasks_cbs_head) { | |
744 | WARN_ON(signal_pending(current)); | |
745 | schedule_timeout_interruptible(HZ/10); | |
746 | } | |
8315f422 PM |
747 | continue; |
748 | } | |
749 | ||
750 | /* | |
751 | * Wait for all pre-existing t->on_rq and t->nvcsw | |
752 | * transitions to complete. Invoking synchronize_sched() | |
753 | * suffices because all these transitions occur with | |
754 | * interrupts disabled. Without this synchronize_sched(), | |
755 | * a read-side critical section that started before the | |
756 | * grace period might be incorrectly seen as having started | |
757 | * after the grace period. | |
758 | * | |
759 | * This synchronize_sched() also dispenses with the | |
760 | * need for a memory barrier on the first store to | |
761 | * ->rcu_tasks_holdout, as it forces the store to happen | |
762 | * after the beginning of the grace period. | |
763 | */ | |
764 | synchronize_sched(); | |
765 | ||
766 | /* | |
767 | * There were callbacks, so we need to wait for an | |
768 | * RCU-tasks grace period. Start off by scanning | |
769 | * the task list for tasks that are not already | |
770 | * voluntarily blocked. Mark these tasks and make | |
771 | * a list of them in rcu_tasks_holdouts. | |
772 | */ | |
773 | rcu_read_lock(); | |
774 | for_each_process_thread(g, t) { | |
7d0ae808 | 775 | if (t != current && READ_ONCE(t->on_rq) && |
8315f422 PM |
776 | !is_idle_task(t)) { |
777 | get_task_struct(t); | |
7d0ae808 PM |
778 | t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw); |
779 | WRITE_ONCE(t->rcu_tasks_holdout, true); | |
8315f422 PM |
780 | list_add(&t->rcu_tasks_holdout_list, |
781 | &rcu_tasks_holdouts); | |
782 | } | |
783 | } | |
784 | rcu_read_unlock(); | |
785 | ||
3f95aa81 PM |
786 | /* |
787 | * Wait for tasks that are in the process of exiting. | |
788 | * This does only part of the job, ensuring that all | |
789 | * tasks that were previously exiting reach the point | |
790 | * where they have disabled preemption, allowing the | |
791 | * later synchronize_sched() to finish the job. | |
792 | */ | |
793 | synchronize_srcu(&tasks_rcu_exit_srcu); | |
794 | ||
8315f422 PM |
795 | /* |
796 | * Each pass through the following loop scans the list | |
797 | * of holdout tasks, removing any that are no longer | |
798 | * holdouts. When the list is empty, we are done. | |
799 | */ | |
52db30ab | 800 | lastreport = jiffies; |
8315f422 | 801 | while (!list_empty(&rcu_tasks_holdouts)) { |
52db30ab PM |
802 | bool firstreport; |
803 | bool needreport; | |
804 | int rtst; | |
8f20a5e8 | 805 | struct task_struct *t1; |
52db30ab | 806 | |
8315f422 | 807 | schedule_timeout_interruptible(HZ); |
7d0ae808 | 808 | rtst = READ_ONCE(rcu_task_stall_timeout); |
52db30ab PM |
809 | needreport = rtst > 0 && |
810 | time_after(jiffies, lastreport + rtst); | |
811 | if (needreport) | |
812 | lastreport = jiffies; | |
813 | firstreport = true; | |
8315f422 | 814 | WARN_ON(signal_pending(current)); |
8f20a5e8 PM |
815 | list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, |
816 | rcu_tasks_holdout_list) { | |
52db30ab | 817 | check_holdout_task(t, needreport, &firstreport); |
8f20a5e8 PM |
818 | cond_resched(); |
819 | } | |
8315f422 PM |
820 | } |
821 | ||
822 | /* | |
823 | * Because ->on_rq and ->nvcsw are not guaranteed | |
824 | * to have a full memory barriers prior to them in the | |
825 | * schedule() path, memory reordering on other CPUs could | |
826 | * cause their RCU-tasks read-side critical sections to | |
827 | * extend past the end of the grace period. However, | |
828 | * because these ->nvcsw updates are carried out with | |
829 | * interrupts disabled, we can use synchronize_sched() | |
830 | * to force the needed ordering on all such CPUs. | |
831 | * | |
832 | * This synchronize_sched() also confines all | |
833 | * ->rcu_tasks_holdout accesses to be within the grace | |
834 | * period, avoiding the need for memory barriers for | |
835 | * ->rcu_tasks_holdout accesses. | |
3f95aa81 PM |
836 | * |
837 | * In addition, this synchronize_sched() waits for exiting | |
838 | * tasks to complete their final preempt_disable() region | |
839 | * of execution, cleaning up after the synchronize_srcu() | |
840 | * above. | |
8315f422 PM |
841 | */ |
842 | synchronize_sched(); | |
843 | ||
844 | /* Invoke the callbacks. */ | |
845 | while (list) { | |
846 | next = list->next; | |
847 | local_bh_disable(); | |
848 | list->func(list); | |
849 | local_bh_enable(); | |
850 | list = next; | |
851 | cond_resched(); | |
852 | } | |
c7b24d2b | 853 | schedule_timeout_uninterruptible(HZ/10); |
8315f422 PM |
854 | } |
855 | } | |
856 | ||
c63eb17f PM |
857 | /* Spawn rcu_tasks_kthread() at core_initcall() time. */ |
858 | static int __init rcu_spawn_tasks_kthread(void) | |
8315f422 | 859 | { |
84a8f446 | 860 | struct task_struct *t; |
8315f422 PM |
861 | |
862 | t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread"); | |
863 | BUG_ON(IS_ERR(t)); | |
84a8f446 | 864 | smp_mb(); /* Ensure others see full kthread. */ |
7d0ae808 | 865 | WRITE_ONCE(rcu_tasks_kthread_ptr, t); |
c63eb17f | 866 | return 0; |
8315f422 | 867 | } |
c63eb17f | 868 | core_initcall(rcu_spawn_tasks_kthread); |
8315f422 | 869 | |
ccdd29ff PM |
870 | /* Do the srcu_read_lock() for the above synchronize_srcu(). */ |
871 | void exit_tasks_rcu_start(void) | |
872 | { | |
873 | preempt_disable(); | |
874 | current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu); | |
875 | preempt_enable(); | |
876 | } | |
877 | ||
878 | /* Do the srcu_read_unlock() for the above synchronize_srcu(). */ | |
879 | void exit_tasks_rcu_finish(void) | |
880 | { | |
881 | preempt_disable(); | |
882 | __srcu_read_unlock(&tasks_rcu_exit_srcu, current->rcu_tasks_idx); | |
883 | preempt_enable(); | |
884 | } | |
885 | ||
8315f422 | 886 | #endif /* #ifdef CONFIG_TASKS_RCU */ |
aa23c6fb | 887 | |
59d80fd8 PM |
888 | #ifndef CONFIG_TINY_RCU |
889 | ||
890 | /* | |
891 | * Print any non-default Tasks RCU settings. | |
892 | */ | |
893 | static void __init rcu_tasks_bootup_oddness(void) | |
894 | { | |
895 | #ifdef CONFIG_TASKS_RCU | |
896 | if (rcu_task_stall_timeout != RCU_TASK_STALL_TIMEOUT) | |
897 | pr_info("\tTasks-RCU CPU stall warnings timeout set to %d (rcu_task_stall_timeout).\n", rcu_task_stall_timeout); | |
898 | else | |
899 | pr_info("\tTasks RCU enabled.\n"); | |
900 | #endif /* #ifdef CONFIG_TASKS_RCU */ | |
901 | } | |
902 | ||
903 | #endif /* #ifndef CONFIG_TINY_RCU */ | |
904 | ||
aa23c6fb PK |
905 | #ifdef CONFIG_PROVE_RCU |
906 | ||
907 | /* | |
908 | * Early boot self test parameters, one for each flavor | |
909 | */ | |
910 | static bool rcu_self_test; | |
911 | static bool rcu_self_test_bh; | |
912 | static bool rcu_self_test_sched; | |
913 | ||
914 | module_param(rcu_self_test, bool, 0444); | |
915 | module_param(rcu_self_test_bh, bool, 0444); | |
916 | module_param(rcu_self_test_sched, bool, 0444); | |
917 | ||
918 | static int rcu_self_test_counter; | |
919 | ||
920 | static void test_callback(struct rcu_head *r) | |
921 | { | |
922 | rcu_self_test_counter++; | |
923 | pr_info("RCU test callback executed %d\n", rcu_self_test_counter); | |
924 | } | |
925 | ||
926 | static void early_boot_test_call_rcu(void) | |
927 | { | |
928 | static struct rcu_head head; | |
929 | ||
930 | call_rcu(&head, test_callback); | |
931 | } | |
932 | ||
933 | static void early_boot_test_call_rcu_bh(void) | |
934 | { | |
935 | static struct rcu_head head; | |
936 | ||
937 | call_rcu_bh(&head, test_callback); | |
938 | } | |
939 | ||
940 | static void early_boot_test_call_rcu_sched(void) | |
941 | { | |
942 | static struct rcu_head head; | |
943 | ||
944 | call_rcu_sched(&head, test_callback); | |
945 | } | |
946 | ||
947 | void rcu_early_boot_tests(void) | |
948 | { | |
949 | pr_info("Running RCU self tests\n"); | |
950 | ||
951 | if (rcu_self_test) | |
952 | early_boot_test_call_rcu(); | |
953 | if (rcu_self_test_bh) | |
954 | early_boot_test_call_rcu_bh(); | |
955 | if (rcu_self_test_sched) | |
956 | early_boot_test_call_rcu_sched(); | |
52d7e48b | 957 | rcu_test_sync_prims(); |
aa23c6fb PK |
958 | } |
959 | ||
960 | static int rcu_verify_early_boot_tests(void) | |
961 | { | |
962 | int ret = 0; | |
963 | int early_boot_test_counter = 0; | |
964 | ||
965 | if (rcu_self_test) { | |
966 | early_boot_test_counter++; | |
967 | rcu_barrier(); | |
968 | } | |
969 | if (rcu_self_test_bh) { | |
970 | early_boot_test_counter++; | |
971 | rcu_barrier_bh(); | |
972 | } | |
973 | if (rcu_self_test_sched) { | |
974 | early_boot_test_counter++; | |
975 | rcu_barrier_sched(); | |
976 | } | |
977 | ||
978 | if (rcu_self_test_counter != early_boot_test_counter) { | |
979 | WARN_ON(1); | |
980 | ret = -1; | |
981 | } | |
982 | ||
983 | return ret; | |
984 | } | |
985 | late_initcall(rcu_verify_early_boot_tests); | |
986 | #else | |
987 | void rcu_early_boot_tests(void) {} | |
988 | #endif /* CONFIG_PROVE_RCU */ | |
59d80fd8 PM |
989 | |
990 | #ifndef CONFIG_TINY_RCU | |
991 | ||
992 | /* | |
993 | * Print any significant non-default boot-time settings. | |
994 | */ | |
995 | void __init rcupdate_announce_bootup_oddness(void) | |
996 | { | |
997 | if (rcu_normal) | |
998 | pr_info("\tNo expedited grace period (rcu_normal).\n"); | |
999 | else if (rcu_normal_after_boot) | |
1000 | pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n"); | |
1001 | else if (rcu_expedited) | |
1002 | pr_info("\tAll grace periods are expedited (rcu_expedited).\n"); | |
1003 | if (rcu_cpu_stall_suppress) | |
1004 | pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n"); | |
1005 | if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT) | |
1006 | pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout); | |
1007 | rcu_tasks_bootup_oddness(); | |
1008 | } | |
1009 | ||
1010 | #endif /* #ifndef CONFIG_TINY_RCU */ |