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