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1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/kdebug.h>
3#include <linux/kprobes.h>
4#include <linux/export.h>
5#include <linux/notifier.h>
6#include <linux/rcupdate.h>
7#include <linux/vmalloc.h>
8#include <linux/reboot.h>
9
10/*
11 * Notifier list for kernel code which wants to be called
12 * at shutdown. This is used to stop any idling DMA operations
13 * and the like.
14 */
15BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
16
17/*
18 * Notifier chain core routines. The exported routines below
19 * are layered on top of these, with appropriate locking added.
20 */
21
22static int notifier_chain_register(struct notifier_block **nl,
23 struct notifier_block *n)
24{
25 while ((*nl) != NULL) {
26 WARN_ONCE(((*nl) == n), "double register detected");
27 if (n->priority > (*nl)->priority)
28 break;
29 nl = &((*nl)->next);
30 }
31 n->next = *nl;
32 rcu_assign_pointer(*nl, n);
33 return 0;
34}
35
36static int notifier_chain_cond_register(struct notifier_block **nl,
37 struct notifier_block *n)
38{
39 while ((*nl) != NULL) {
40 if ((*nl) == n)
41 return 0;
42 if (n->priority > (*nl)->priority)
43 break;
44 nl = &((*nl)->next);
45 }
46 n->next = *nl;
47 rcu_assign_pointer(*nl, n);
48 return 0;
49}
50
51static int notifier_chain_unregister(struct notifier_block **nl,
52 struct notifier_block *n)
53{
54 while ((*nl) != NULL) {
55 if ((*nl) == n) {
56 rcu_assign_pointer(*nl, n->next);
57 return 0;
58 }
59 nl = &((*nl)->next);
60 }
61 return -ENOENT;
62}
63
64/**
65 * notifier_call_chain - Informs the registered notifiers about an event.
66 * @nl: Pointer to head of the blocking notifier chain
67 * @val: Value passed unmodified to notifier function
68 * @v: Pointer passed unmodified to notifier function
69 * @nr_to_call: Number of notifier functions to be called. Don't care
70 * value of this parameter is -1.
71 * @nr_calls: Records the number of notifications sent. Don't care
72 * value of this field is NULL.
73 * @returns: notifier_call_chain returns the value returned by the
74 * last notifier function called.
75 */
76static int notifier_call_chain(struct notifier_block **nl,
77 unsigned long val, void *v,
78 int nr_to_call, int *nr_calls)
79{
80 int ret = NOTIFY_DONE;
81 struct notifier_block *nb, *next_nb;
82
83 nb = rcu_dereference_raw(*nl);
84
85 while (nb && nr_to_call) {
86 next_nb = rcu_dereference_raw(nb->next);
87
88#ifdef CONFIG_DEBUG_NOTIFIERS
89 if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
90 WARN(1, "Invalid notifier called!");
91 nb = next_nb;
92 continue;
93 }
94#endif
95 ret = nb->notifier_call(nb, val, v);
96
97 if (nr_calls)
98 (*nr_calls)++;
99
100 if (ret & NOTIFY_STOP_MASK)
101 break;
102 nb = next_nb;
103 nr_to_call--;
104 }
105 return ret;
106}
107NOKPROBE_SYMBOL(notifier_call_chain);
108
109/*
110 * Atomic notifier chain routines. Registration and unregistration
111 * use a spinlock, and call_chain is synchronized by RCU (no locks).
112 */
113
114/**
115 * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
116 * @nh: Pointer to head of the atomic notifier chain
117 * @n: New entry in notifier chain
118 *
119 * Adds a notifier to an atomic notifier chain.
120 *
121 * Currently always returns zero.
122 */
123int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
124 struct notifier_block *n)
125{
126 unsigned long flags;
127 int ret;
128
129 spin_lock_irqsave(&nh->lock, flags);
130 ret = notifier_chain_register(&nh->head, n);
131 spin_unlock_irqrestore(&nh->lock, flags);
132 return ret;
133}
134EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
135
136/**
137 * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
138 * @nh: Pointer to head of the atomic notifier chain
139 * @n: Entry to remove from notifier chain
140 *
141 * Removes a notifier from an atomic notifier chain.
142 *
143 * Returns zero on success or %-ENOENT on failure.
144 */
145int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
146 struct notifier_block *n)
147{
148 unsigned long flags;
149 int ret;
150
151 spin_lock_irqsave(&nh->lock, flags);
152 ret = notifier_chain_unregister(&nh->head, n);
153 spin_unlock_irqrestore(&nh->lock, flags);
154 synchronize_rcu();
155 return ret;
156}
157EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
158
159/**
160 * __atomic_notifier_call_chain - Call functions in an atomic notifier chain
161 * @nh: Pointer to head of the atomic notifier chain
162 * @val: Value passed unmodified to notifier function
163 * @v: Pointer passed unmodified to notifier function
164 * @nr_to_call: See the comment for notifier_call_chain.
165 * @nr_calls: See the comment for notifier_call_chain.
166 *
167 * Calls each function in a notifier chain in turn. The functions
168 * run in an atomic context, so they must not block.
169 * This routine uses RCU to synchronize with changes to the chain.
170 *
171 * If the return value of the notifier can be and'ed
172 * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
173 * will return immediately, with the return value of
174 * the notifier function which halted execution.
175 * Otherwise the return value is the return value
176 * of the last notifier function called.
177 */
178int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
179 unsigned long val, void *v,
180 int nr_to_call, int *nr_calls)
181{
182 int ret;
183
184 rcu_read_lock();
185 ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
186 rcu_read_unlock();
187 return ret;
188}
189EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);
190NOKPROBE_SYMBOL(__atomic_notifier_call_chain);
191
192int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
193 unsigned long val, void *v)
194{
195 return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
196}
197EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
198NOKPROBE_SYMBOL(atomic_notifier_call_chain);
199
200/*
201 * Blocking notifier chain routines. All access to the chain is
202 * synchronized by an rwsem.
203 */
204
205/**
206 * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
207 * @nh: Pointer to head of the blocking notifier chain
208 * @n: New entry in notifier chain
209 *
210 * Adds a notifier to a blocking notifier chain.
211 * Must be called in process context.
212 *
213 * Currently always returns zero.
214 */
215int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
216 struct notifier_block *n)
217{
218 int ret;
219
220 /*
221 * This code gets used during boot-up, when task switching is
222 * not yet working and interrupts must remain disabled. At
223 * such times we must not call down_write().
224 */
225 if (unlikely(system_state == SYSTEM_BOOTING))
226 return notifier_chain_register(&nh->head, n);
227
228 down_write(&nh->rwsem);
229 ret = notifier_chain_register(&nh->head, n);
230 up_write(&nh->rwsem);
231 return ret;
232}
233EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
234
235/**
236 * blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain
237 * @nh: Pointer to head of the blocking notifier chain
238 * @n: New entry in notifier chain
239 *
240 * Adds a notifier to a blocking notifier chain, only if not already
241 * present in the chain.
242 * Must be called in process context.
243 *
244 * Currently always returns zero.
245 */
246int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh,
247 struct notifier_block *n)
248{
249 int ret;
250
251 down_write(&nh->rwsem);
252 ret = notifier_chain_cond_register(&nh->head, n);
253 up_write(&nh->rwsem);
254 return ret;
255}
256EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register);
257
258/**
259 * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
260 * @nh: Pointer to head of the blocking notifier chain
261 * @n: Entry to remove from notifier chain
262 *
263 * Removes a notifier from a blocking notifier chain.
264 * Must be called from process context.
265 *
266 * Returns zero on success or %-ENOENT on failure.
267 */
268int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
269 struct notifier_block *n)
270{
271 int ret;
272
273 /*
274 * This code gets used during boot-up, when task switching is
275 * not yet working and interrupts must remain disabled. At
276 * such times we must not call down_write().
277 */
278 if (unlikely(system_state == SYSTEM_BOOTING))
279 return notifier_chain_unregister(&nh->head, n);
280
281 down_write(&nh->rwsem);
282 ret = notifier_chain_unregister(&nh->head, n);
283 up_write(&nh->rwsem);
284 return ret;
285}
286EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
287
288/**
289 * __blocking_notifier_call_chain - Call functions in a blocking notifier chain
290 * @nh: Pointer to head of the blocking notifier chain
291 * @val: Value passed unmodified to notifier function
292 * @v: Pointer passed unmodified to notifier function
293 * @nr_to_call: See comment for notifier_call_chain.
294 * @nr_calls: See comment for notifier_call_chain.
295 *
296 * Calls each function in a notifier chain in turn. The functions
297 * run in a process context, so they are allowed to block.
298 *
299 * If the return value of the notifier can be and'ed
300 * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
301 * will return immediately, with the return value of
302 * the notifier function which halted execution.
303 * Otherwise the return value is the return value
304 * of the last notifier function called.
305 */
306int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
307 unsigned long val, void *v,
308 int nr_to_call, int *nr_calls)
309{
310 int ret = NOTIFY_DONE;
311
312 /*
313 * We check the head outside the lock, but if this access is
314 * racy then it does not matter what the result of the test
315 * is, we re-check the list after having taken the lock anyway:
316 */
317 if (rcu_access_pointer(nh->head)) {
318 down_read(&nh->rwsem);
319 ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
320 nr_calls);
321 up_read(&nh->rwsem);
322 }
323 return ret;
324}
325EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
326
327int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
328 unsigned long val, void *v)
329{
330 return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
331}
332EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
333
334/*
335 * Raw notifier chain routines. There is no protection;
336 * the caller must provide it. Use at your own risk!
337 */
338
339/**
340 * raw_notifier_chain_register - Add notifier to a raw notifier chain
341 * @nh: Pointer to head of the raw notifier chain
342 * @n: New entry in notifier chain
343 *
344 * Adds a notifier to a raw notifier chain.
345 * All locking must be provided by the caller.
346 *
347 * Currently always returns zero.
348 */
349int raw_notifier_chain_register(struct raw_notifier_head *nh,
350 struct notifier_block *n)
351{
352 return notifier_chain_register(&nh->head, n);
353}
354EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
355
356/**
357 * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
358 * @nh: Pointer to head of the raw notifier chain
359 * @n: Entry to remove from notifier chain
360 *
361 * Removes a notifier from a raw notifier chain.
362 * All locking must be provided by the caller.
363 *
364 * Returns zero on success or %-ENOENT on failure.
365 */
366int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
367 struct notifier_block *n)
368{
369 return notifier_chain_unregister(&nh->head, n);
370}
371EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
372
373/**
374 * __raw_notifier_call_chain - Call functions in a raw notifier chain
375 * @nh: Pointer to head of the raw notifier chain
376 * @val: Value passed unmodified to notifier function
377 * @v: Pointer passed unmodified to notifier function
378 * @nr_to_call: See comment for notifier_call_chain.
379 * @nr_calls: See comment for notifier_call_chain
380 *
381 * Calls each function in a notifier chain in turn. The functions
382 * run in an undefined context.
383 * All locking must be provided by the caller.
384 *
385 * If the return value of the notifier can be and'ed
386 * with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
387 * will return immediately, with the return value of
388 * the notifier function which halted execution.
389 * Otherwise the return value is the return value
390 * of the last notifier function called.
391 */
392int __raw_notifier_call_chain(struct raw_notifier_head *nh,
393 unsigned long val, void *v,
394 int nr_to_call, int *nr_calls)
395{
396 return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
397}
398EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
399
400int raw_notifier_call_chain(struct raw_notifier_head *nh,
401 unsigned long val, void *v)
402{
403 return __raw_notifier_call_chain(nh, val, v, -1, NULL);
404}
405EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
406
407#ifdef CONFIG_SRCU
408/*
409 * SRCU notifier chain routines. Registration and unregistration
410 * use a mutex, and call_chain is synchronized by SRCU (no locks).
411 */
412
413/**
414 * srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
415 * @nh: Pointer to head of the SRCU notifier chain
416 * @n: New entry in notifier chain
417 *
418 * Adds a notifier to an SRCU notifier chain.
419 * Must be called in process context.
420 *
421 * Currently always returns zero.
422 */
423int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
424 struct notifier_block *n)
425{
426 int ret;
427
428 /*
429 * This code gets used during boot-up, when task switching is
430 * not yet working and interrupts must remain disabled. At
431 * such times we must not call mutex_lock().
432 */
433 if (unlikely(system_state == SYSTEM_BOOTING))
434 return notifier_chain_register(&nh->head, n);
435
436 mutex_lock(&nh->mutex);
437 ret = notifier_chain_register(&nh->head, n);
438 mutex_unlock(&nh->mutex);
439 return ret;
440}
441EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
442
443/**
444 * srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
445 * @nh: Pointer to head of the SRCU notifier chain
446 * @n: Entry to remove from notifier chain
447 *
448 * Removes a notifier from an SRCU notifier chain.
449 * Must be called from process context.
450 *
451 * Returns zero on success or %-ENOENT on failure.
452 */
453int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
454 struct notifier_block *n)
455{
456 int ret;
457
458 /*
459 * This code gets used during boot-up, when task switching is
460 * not yet working and interrupts must remain disabled. At
461 * such times we must not call mutex_lock().
462 */
463 if (unlikely(system_state == SYSTEM_BOOTING))
464 return notifier_chain_unregister(&nh->head, n);
465
466 mutex_lock(&nh->mutex);
467 ret = notifier_chain_unregister(&nh->head, n);
468 mutex_unlock(&nh->mutex);
469 synchronize_srcu(&nh->srcu);
470 return ret;
471}
472EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
473
474/**
475 * __srcu_notifier_call_chain - Call functions in an SRCU notifier chain
476 * @nh: Pointer to head of the SRCU notifier chain
477 * @val: Value passed unmodified to notifier function
478 * @v: Pointer passed unmodified to notifier function
479 * @nr_to_call: See comment for notifier_call_chain.
480 * @nr_calls: See comment for notifier_call_chain
481 *
482 * Calls each function in a notifier chain in turn. The functions
483 * run in a process context, so they are allowed to block.
484 *
485 * If the return value of the notifier can be and'ed
486 * with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
487 * will return immediately, with the return value of
488 * the notifier function which halted execution.
489 * Otherwise the return value is the return value
490 * of the last notifier function called.
491 */
492int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
493 unsigned long val, void *v,
494 int nr_to_call, int *nr_calls)
495{
496 int ret;
497 int idx;
498
499 idx = srcu_read_lock(&nh->srcu);
500 ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
501 srcu_read_unlock(&nh->srcu, idx);
502 return ret;
503}
504EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain);
505
506int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
507 unsigned long val, void *v)
508{
509 return __srcu_notifier_call_chain(nh, val, v, -1, NULL);
510}
511EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
512
513/**
514 * srcu_init_notifier_head - Initialize an SRCU notifier head
515 * @nh: Pointer to head of the srcu notifier chain
516 *
517 * Unlike other sorts of notifier heads, SRCU notifier heads require
518 * dynamic initialization. Be sure to call this routine before
519 * calling any of the other SRCU notifier routines for this head.
520 *
521 * If an SRCU notifier head is deallocated, it must first be cleaned
522 * up by calling srcu_cleanup_notifier_head(). Otherwise the head's
523 * per-cpu data (used by the SRCU mechanism) will leak.
524 */
525void srcu_init_notifier_head(struct srcu_notifier_head *nh)
526{
527 mutex_init(&nh->mutex);
528 if (init_srcu_struct(&nh->srcu) < 0)
529 BUG();
530 nh->head = NULL;
531}
532EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
533
534#endif /* CONFIG_SRCU */
535
536static ATOMIC_NOTIFIER_HEAD(die_chain);
537
538int notrace notify_die(enum die_val val, const char *str,
539 struct pt_regs *regs, long err, int trap, int sig)
540{
541 struct die_args args = {
542 .regs = regs,
543 .str = str,
544 .err = err,
545 .trapnr = trap,
546 .signr = sig,
547
548 };
549 RCU_LOCKDEP_WARN(!rcu_is_watching(),
550 "notify_die called but RCU thinks we're quiescent");
551 return atomic_notifier_call_chain(&die_chain, val, &args);
552}
553NOKPROBE_SYMBOL(notify_die);
554
555int register_die_notifier(struct notifier_block *nb)
556{
557 vmalloc_sync_all();
558 return atomic_notifier_chain_register(&die_chain, nb);
559}
560EXPORT_SYMBOL_GPL(register_die_notifier);
561
562int unregister_die_notifier(struct notifier_block *nb)
563{
564 return atomic_notifier_chain_unregister(&die_chain, nb);
565}
566EXPORT_SYMBOL_GPL(unregister_die_notifier);
1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/kdebug.h>
3#include <linux/kprobes.h>
4#include <linux/export.h>
5#include <linux/notifier.h>
6#include <linux/rcupdate.h>
7#include <linux/vmalloc.h>
8#include <linux/reboot.h>
9
10/*
11 * Notifier list for kernel code which wants to be called
12 * at shutdown. This is used to stop any idling DMA operations
13 * and the like.
14 */
15BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
16
17/*
18 * Notifier chain core routines. The exported routines below
19 * are layered on top of these, with appropriate locking added.
20 */
21
22static int notifier_chain_register(struct notifier_block **nl,
23 struct notifier_block *n,
24 bool unique_priority)
25{
26 while ((*nl) != NULL) {
27 if (unlikely((*nl) == n)) {
28 WARN(1, "notifier callback %ps already registered",
29 n->notifier_call);
30 return -EEXIST;
31 }
32 if (n->priority > (*nl)->priority)
33 break;
34 if (n->priority == (*nl)->priority && unique_priority)
35 return -EBUSY;
36 nl = &((*nl)->next);
37 }
38 n->next = *nl;
39 rcu_assign_pointer(*nl, n);
40 return 0;
41}
42
43static int notifier_chain_unregister(struct notifier_block **nl,
44 struct notifier_block *n)
45{
46 while ((*nl) != NULL) {
47 if ((*nl) == n) {
48 rcu_assign_pointer(*nl, n->next);
49 return 0;
50 }
51 nl = &((*nl)->next);
52 }
53 return -ENOENT;
54}
55
56/**
57 * notifier_call_chain - Informs the registered notifiers about an event.
58 * @nl: Pointer to head of the blocking notifier chain
59 * @val: Value passed unmodified to notifier function
60 * @v: Pointer passed unmodified to notifier function
61 * @nr_to_call: Number of notifier functions to be called. Don't care
62 * value of this parameter is -1.
63 * @nr_calls: Records the number of notifications sent. Don't care
64 * value of this field is NULL.
65 * Return: notifier_call_chain returns the value returned by the
66 * last notifier function called.
67 */
68static int notifier_call_chain(struct notifier_block **nl,
69 unsigned long val, void *v,
70 int nr_to_call, int *nr_calls)
71{
72 int ret = NOTIFY_DONE;
73 struct notifier_block *nb, *next_nb;
74
75 nb = rcu_dereference_raw(*nl);
76
77 while (nb && nr_to_call) {
78 next_nb = rcu_dereference_raw(nb->next);
79
80#ifdef CONFIG_DEBUG_NOTIFIERS
81 if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
82 WARN(1, "Invalid notifier called!");
83 nb = next_nb;
84 continue;
85 }
86#endif
87 ret = nb->notifier_call(nb, val, v);
88
89 if (nr_calls)
90 (*nr_calls)++;
91
92 if (ret & NOTIFY_STOP_MASK)
93 break;
94 nb = next_nb;
95 nr_to_call--;
96 }
97 return ret;
98}
99NOKPROBE_SYMBOL(notifier_call_chain);
100
101/**
102 * notifier_call_chain_robust - Inform the registered notifiers about an event
103 * and rollback on error.
104 * @nl: Pointer to head of the blocking notifier chain
105 * @val_up: Value passed unmodified to the notifier function
106 * @val_down: Value passed unmodified to the notifier function when recovering
107 * from an error on @val_up
108 * @v: Pointer passed unmodified to the notifier function
109 *
110 * NOTE: It is important the @nl chain doesn't change between the two
111 * invocations of notifier_call_chain() such that we visit the
112 * exact same notifier callbacks; this rules out any RCU usage.
113 *
114 * Return: the return value of the @val_up call.
115 */
116static int notifier_call_chain_robust(struct notifier_block **nl,
117 unsigned long val_up, unsigned long val_down,
118 void *v)
119{
120 int ret, nr = 0;
121
122 ret = notifier_call_chain(nl, val_up, v, -1, &nr);
123 if (ret & NOTIFY_STOP_MASK)
124 notifier_call_chain(nl, val_down, v, nr-1, NULL);
125
126 return ret;
127}
128
129/*
130 * Atomic notifier chain routines. Registration and unregistration
131 * use a spinlock, and call_chain is synchronized by RCU (no locks).
132 */
133
134/**
135 * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
136 * @nh: Pointer to head of the atomic notifier chain
137 * @n: New entry in notifier chain
138 *
139 * Adds a notifier to an atomic notifier chain.
140 *
141 * Returns 0 on success, %-EEXIST on error.
142 */
143int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
144 struct notifier_block *n)
145{
146 unsigned long flags;
147 int ret;
148
149 spin_lock_irqsave(&nh->lock, flags);
150 ret = notifier_chain_register(&nh->head, n, false);
151 spin_unlock_irqrestore(&nh->lock, flags);
152 return ret;
153}
154EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
155
156/**
157 * atomic_notifier_chain_register_unique_prio - Add notifier to an atomic notifier chain
158 * @nh: Pointer to head of the atomic notifier chain
159 * @n: New entry in notifier chain
160 *
161 * Adds a notifier to an atomic notifier chain if there is no other
162 * notifier registered using the same priority.
163 *
164 * Returns 0 on success, %-EEXIST or %-EBUSY on error.
165 */
166int atomic_notifier_chain_register_unique_prio(struct atomic_notifier_head *nh,
167 struct notifier_block *n)
168{
169 unsigned long flags;
170 int ret;
171
172 spin_lock_irqsave(&nh->lock, flags);
173 ret = notifier_chain_register(&nh->head, n, true);
174 spin_unlock_irqrestore(&nh->lock, flags);
175 return ret;
176}
177EXPORT_SYMBOL_GPL(atomic_notifier_chain_register_unique_prio);
178
179/**
180 * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
181 * @nh: Pointer to head of the atomic notifier chain
182 * @n: Entry to remove from notifier chain
183 *
184 * Removes a notifier from an atomic notifier chain.
185 *
186 * Returns zero on success or %-ENOENT on failure.
187 */
188int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
189 struct notifier_block *n)
190{
191 unsigned long flags;
192 int ret;
193
194 spin_lock_irqsave(&nh->lock, flags);
195 ret = notifier_chain_unregister(&nh->head, n);
196 spin_unlock_irqrestore(&nh->lock, flags);
197 synchronize_rcu();
198 return ret;
199}
200EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
201
202/**
203 * atomic_notifier_call_chain - Call functions in an atomic notifier chain
204 * @nh: Pointer to head of the atomic notifier chain
205 * @val: Value passed unmodified to notifier function
206 * @v: Pointer passed unmodified to notifier function
207 *
208 * Calls each function in a notifier chain in turn. The functions
209 * run in an atomic context, so they must not block.
210 * This routine uses RCU to synchronize with changes to the chain.
211 *
212 * If the return value of the notifier can be and'ed
213 * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
214 * will return immediately, with the return value of
215 * the notifier function which halted execution.
216 * Otherwise the return value is the return value
217 * of the last notifier function called.
218 */
219int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
220 unsigned long val, void *v)
221{
222 int ret;
223
224 rcu_read_lock();
225 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
226 rcu_read_unlock();
227
228 return ret;
229}
230EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
231NOKPROBE_SYMBOL(atomic_notifier_call_chain);
232
233/**
234 * atomic_notifier_call_chain_is_empty - Check whether notifier chain is empty
235 * @nh: Pointer to head of the atomic notifier chain
236 *
237 * Checks whether notifier chain is empty.
238 *
239 * Returns true is notifier chain is empty, false otherwise.
240 */
241bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh)
242{
243 return !rcu_access_pointer(nh->head);
244}
245
246/*
247 * Blocking notifier chain routines. All access to the chain is
248 * synchronized by an rwsem.
249 */
250
251static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
252 struct notifier_block *n,
253 bool unique_priority)
254{
255 int ret;
256
257 /*
258 * This code gets used during boot-up, when task switching is
259 * not yet working and interrupts must remain disabled. At
260 * such times we must not call down_write().
261 */
262 if (unlikely(system_state == SYSTEM_BOOTING))
263 return notifier_chain_register(&nh->head, n, unique_priority);
264
265 down_write(&nh->rwsem);
266 ret = notifier_chain_register(&nh->head, n, unique_priority);
267 up_write(&nh->rwsem);
268 return ret;
269}
270
271/**
272 * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
273 * @nh: Pointer to head of the blocking notifier chain
274 * @n: New entry in notifier chain
275 *
276 * Adds a notifier to a blocking notifier chain.
277 * Must be called in process context.
278 *
279 * Returns 0 on success, %-EEXIST on error.
280 */
281int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
282 struct notifier_block *n)
283{
284 return __blocking_notifier_chain_register(nh, n, false);
285}
286EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
287
288/**
289 * blocking_notifier_chain_register_unique_prio - Add notifier to a blocking notifier chain
290 * @nh: Pointer to head of the blocking notifier chain
291 * @n: New entry in notifier chain
292 *
293 * Adds a notifier to an blocking notifier chain if there is no other
294 * notifier registered using the same priority.
295 *
296 * Returns 0 on success, %-EEXIST or %-EBUSY on error.
297 */
298int blocking_notifier_chain_register_unique_prio(struct blocking_notifier_head *nh,
299 struct notifier_block *n)
300{
301 return __blocking_notifier_chain_register(nh, n, true);
302}
303EXPORT_SYMBOL_GPL(blocking_notifier_chain_register_unique_prio);
304
305/**
306 * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
307 * @nh: Pointer to head of the blocking notifier chain
308 * @n: Entry to remove from notifier chain
309 *
310 * Removes a notifier from a blocking notifier chain.
311 * Must be called from process context.
312 *
313 * Returns zero on success or %-ENOENT on failure.
314 */
315int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
316 struct notifier_block *n)
317{
318 int ret;
319
320 /*
321 * This code gets used during boot-up, when task switching is
322 * not yet working and interrupts must remain disabled. At
323 * such times we must not call down_write().
324 */
325 if (unlikely(system_state == SYSTEM_BOOTING))
326 return notifier_chain_unregister(&nh->head, n);
327
328 down_write(&nh->rwsem);
329 ret = notifier_chain_unregister(&nh->head, n);
330 up_write(&nh->rwsem);
331 return ret;
332}
333EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
334
335int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh,
336 unsigned long val_up, unsigned long val_down, void *v)
337{
338 int ret = NOTIFY_DONE;
339
340 /*
341 * We check the head outside the lock, but if this access is
342 * racy then it does not matter what the result of the test
343 * is, we re-check the list after having taken the lock anyway:
344 */
345 if (rcu_access_pointer(nh->head)) {
346 down_read(&nh->rwsem);
347 ret = notifier_call_chain_robust(&nh->head, val_up, val_down, v);
348 up_read(&nh->rwsem);
349 }
350 return ret;
351}
352EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_robust);
353
354/**
355 * blocking_notifier_call_chain - Call functions in a blocking notifier chain
356 * @nh: Pointer to head of the blocking notifier chain
357 * @val: Value passed unmodified to notifier function
358 * @v: Pointer passed unmodified to notifier function
359 *
360 * Calls each function in a notifier chain in turn. The functions
361 * run in a process context, so they are allowed to block.
362 *
363 * If the return value of the notifier can be and'ed
364 * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
365 * will return immediately, with the return value of
366 * the notifier function which halted execution.
367 * Otherwise the return value is the return value
368 * of the last notifier function called.
369 */
370int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
371 unsigned long val, void *v)
372{
373 int ret = NOTIFY_DONE;
374
375 /*
376 * We check the head outside the lock, but if this access is
377 * racy then it does not matter what the result of the test
378 * is, we re-check the list after having taken the lock anyway:
379 */
380 if (rcu_access_pointer(nh->head)) {
381 down_read(&nh->rwsem);
382 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
383 up_read(&nh->rwsem);
384 }
385 return ret;
386}
387EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
388
389/*
390 * Raw notifier chain routines. There is no protection;
391 * the caller must provide it. Use at your own risk!
392 */
393
394/**
395 * raw_notifier_chain_register - Add notifier to a raw notifier chain
396 * @nh: Pointer to head of the raw notifier chain
397 * @n: New entry in notifier chain
398 *
399 * Adds a notifier to a raw notifier chain.
400 * All locking must be provided by the caller.
401 *
402 * Returns 0 on success, %-EEXIST on error.
403 */
404int raw_notifier_chain_register(struct raw_notifier_head *nh,
405 struct notifier_block *n)
406{
407 return notifier_chain_register(&nh->head, n, false);
408}
409EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
410
411/**
412 * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
413 * @nh: Pointer to head of the raw notifier chain
414 * @n: Entry to remove from notifier chain
415 *
416 * Removes a notifier from a raw notifier chain.
417 * All locking must be provided by the caller.
418 *
419 * Returns zero on success or %-ENOENT on failure.
420 */
421int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
422 struct notifier_block *n)
423{
424 return notifier_chain_unregister(&nh->head, n);
425}
426EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
427
428int raw_notifier_call_chain_robust(struct raw_notifier_head *nh,
429 unsigned long val_up, unsigned long val_down, void *v)
430{
431 return notifier_call_chain_robust(&nh->head, val_up, val_down, v);
432}
433EXPORT_SYMBOL_GPL(raw_notifier_call_chain_robust);
434
435/**
436 * raw_notifier_call_chain - Call functions in a raw notifier chain
437 * @nh: Pointer to head of the raw notifier chain
438 * @val: Value passed unmodified to notifier function
439 * @v: Pointer passed unmodified to notifier function
440 *
441 * Calls each function in a notifier chain in turn. The functions
442 * run in an undefined context.
443 * All locking must be provided by the caller.
444 *
445 * If the return value of the notifier can be and'ed
446 * with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
447 * will return immediately, with the return value of
448 * the notifier function which halted execution.
449 * Otherwise the return value is the return value
450 * of the last notifier function called.
451 */
452int raw_notifier_call_chain(struct raw_notifier_head *nh,
453 unsigned long val, void *v)
454{
455 return notifier_call_chain(&nh->head, val, v, -1, NULL);
456}
457EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
458
459#ifdef CONFIG_SRCU
460/*
461 * SRCU notifier chain routines. Registration and unregistration
462 * use a mutex, and call_chain is synchronized by SRCU (no locks).
463 */
464
465/**
466 * srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
467 * @nh: Pointer to head of the SRCU notifier chain
468 * @n: New entry in notifier chain
469 *
470 * Adds a notifier to an SRCU notifier chain.
471 * Must be called in process context.
472 *
473 * Returns 0 on success, %-EEXIST on error.
474 */
475int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
476 struct notifier_block *n)
477{
478 int ret;
479
480 /*
481 * This code gets used during boot-up, when task switching is
482 * not yet working and interrupts must remain disabled. At
483 * such times we must not call mutex_lock().
484 */
485 if (unlikely(system_state == SYSTEM_BOOTING))
486 return notifier_chain_register(&nh->head, n, false);
487
488 mutex_lock(&nh->mutex);
489 ret = notifier_chain_register(&nh->head, n, false);
490 mutex_unlock(&nh->mutex);
491 return ret;
492}
493EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
494
495/**
496 * srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
497 * @nh: Pointer to head of the SRCU notifier chain
498 * @n: Entry to remove from notifier chain
499 *
500 * Removes a notifier from an SRCU notifier chain.
501 * Must be called from process context.
502 *
503 * Returns zero on success or %-ENOENT on failure.
504 */
505int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
506 struct notifier_block *n)
507{
508 int ret;
509
510 /*
511 * This code gets used during boot-up, when task switching is
512 * not yet working and interrupts must remain disabled. At
513 * such times we must not call mutex_lock().
514 */
515 if (unlikely(system_state == SYSTEM_BOOTING))
516 return notifier_chain_unregister(&nh->head, n);
517
518 mutex_lock(&nh->mutex);
519 ret = notifier_chain_unregister(&nh->head, n);
520 mutex_unlock(&nh->mutex);
521 synchronize_srcu(&nh->srcu);
522 return ret;
523}
524EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
525
526/**
527 * srcu_notifier_call_chain - Call functions in an SRCU notifier chain
528 * @nh: Pointer to head of the SRCU notifier chain
529 * @val: Value passed unmodified to notifier function
530 * @v: Pointer passed unmodified to notifier function
531 *
532 * Calls each function in a notifier chain in turn. The functions
533 * run in a process context, so they are allowed to block.
534 *
535 * If the return value of the notifier can be and'ed
536 * with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
537 * will return immediately, with the return value of
538 * the notifier function which halted execution.
539 * Otherwise the return value is the return value
540 * of the last notifier function called.
541 */
542int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
543 unsigned long val, void *v)
544{
545 int ret;
546 int idx;
547
548 idx = srcu_read_lock(&nh->srcu);
549 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
550 srcu_read_unlock(&nh->srcu, idx);
551 return ret;
552}
553EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
554
555/**
556 * srcu_init_notifier_head - Initialize an SRCU notifier head
557 * @nh: Pointer to head of the srcu notifier chain
558 *
559 * Unlike other sorts of notifier heads, SRCU notifier heads require
560 * dynamic initialization. Be sure to call this routine before
561 * calling any of the other SRCU notifier routines for this head.
562 *
563 * If an SRCU notifier head is deallocated, it must first be cleaned
564 * up by calling srcu_cleanup_notifier_head(). Otherwise the head's
565 * per-cpu data (used by the SRCU mechanism) will leak.
566 */
567void srcu_init_notifier_head(struct srcu_notifier_head *nh)
568{
569 mutex_init(&nh->mutex);
570 if (init_srcu_struct(&nh->srcu) < 0)
571 BUG();
572 nh->head = NULL;
573}
574EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
575
576#endif /* CONFIG_SRCU */
577
578static ATOMIC_NOTIFIER_HEAD(die_chain);
579
580int notrace notify_die(enum die_val val, const char *str,
581 struct pt_regs *regs, long err, int trap, int sig)
582{
583 struct die_args args = {
584 .regs = regs,
585 .str = str,
586 .err = err,
587 .trapnr = trap,
588 .signr = sig,
589
590 };
591 RCU_LOCKDEP_WARN(!rcu_is_watching(),
592 "notify_die called but RCU thinks we're quiescent");
593 return atomic_notifier_call_chain(&die_chain, val, &args);
594}
595NOKPROBE_SYMBOL(notify_die);
596
597int register_die_notifier(struct notifier_block *nb)
598{
599 return atomic_notifier_chain_register(&die_chain, nb);
600}
601EXPORT_SYMBOL_GPL(register_die_notifier);
602
603int unregister_die_notifier(struct notifier_block *nb)
604{
605 return atomic_notifier_chain_unregister(&die_chain, nb);
606}
607EXPORT_SYMBOL_GPL(unregister_die_notifier);