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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 __kprobes 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}
105
106/*
107 * Atomic notifier chain routines. Registration and unregistration
108 * use a spinlock, and call_chain is synchronized by RCU (no locks).
109 */
110
111/**
112 * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
113 * @nh: Pointer to head of the atomic notifier chain
114 * @n: New entry in notifier chain
115 *
116 * Adds a notifier to an atomic notifier chain.
117 *
118 * Currently always returns zero.
119 */
120int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
121 struct notifier_block *n)
122{
123 unsigned long flags;
124 int ret;
125
126 spin_lock_irqsave(&nh->lock, flags);
127 ret = notifier_chain_register(&nh->head, n);
128 spin_unlock_irqrestore(&nh->lock, flags);
129 return ret;
130}
131EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
132
133/**
134 * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
135 * @nh: Pointer to head of the atomic notifier chain
136 * @n: Entry to remove from notifier chain
137 *
138 * Removes a notifier from an atomic notifier chain.
139 *
140 * Returns zero on success or %-ENOENT on failure.
141 */
142int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
143 struct notifier_block *n)
144{
145 unsigned long flags;
146 int ret;
147
148 spin_lock_irqsave(&nh->lock, flags);
149 ret = notifier_chain_unregister(&nh->head, n);
150 spin_unlock_irqrestore(&nh->lock, flags);
151 synchronize_rcu();
152 return ret;
153}
154EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
155
156/**
157 * __atomic_notifier_call_chain - Call functions in an atomic notifier chain
158 * @nh: Pointer to head of the atomic notifier chain
159 * @val: Value passed unmodified to notifier function
160 * @v: Pointer passed unmodified to notifier function
161 * @nr_to_call: See the comment for notifier_call_chain.
162 * @nr_calls: See the comment for notifier_call_chain.
163 *
164 * Calls each function in a notifier chain in turn. The functions
165 * run in an atomic context, so they must not block.
166 * This routine uses RCU to synchronize with changes to the chain.
167 *
168 * If the return value of the notifier can be and'ed
169 * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
170 * will return immediately, with the return value of
171 * the notifier function which halted execution.
172 * Otherwise the return value is the return value
173 * of the last notifier function called.
174 */
175int __kprobes __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
176 unsigned long val, void *v,
177 int nr_to_call, int *nr_calls)
178{
179 int ret;
180
181 rcu_read_lock();
182 ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
183 rcu_read_unlock();
184 return ret;
185}
186EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);
187
188int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
189 unsigned long val, void *v)
190{
191 return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
192}
193EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
194
195/*
196 * Blocking notifier chain routines. All access to the chain is
197 * synchronized by an rwsem.
198 */
199
200/**
201 * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
202 * @nh: Pointer to head of the blocking notifier chain
203 * @n: New entry in notifier chain
204 *
205 * Adds a notifier to a blocking notifier chain.
206 * Must be called in process context.
207 *
208 * Currently always returns zero.
209 */
210int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
211 struct notifier_block *n)
212{
213 int ret;
214
215 /*
216 * This code gets used during boot-up, when task switching is
217 * not yet working and interrupts must remain disabled. At
218 * such times we must not call down_write().
219 */
220 if (unlikely(system_state == SYSTEM_BOOTING))
221 return notifier_chain_register(&nh->head, n);
222
223 down_write(&nh->rwsem);
224 ret = notifier_chain_register(&nh->head, n);
225 up_write(&nh->rwsem);
226 return ret;
227}
228EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
229
230/**
231 * blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain
232 * @nh: Pointer to head of the blocking notifier chain
233 * @n: New entry in notifier chain
234 *
235 * Adds a notifier to a blocking notifier chain, only if not already
236 * present in the chain.
237 * Must be called in process context.
238 *
239 * Currently always returns zero.
240 */
241int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh,
242 struct notifier_block *n)
243{
244 int ret;
245
246 down_write(&nh->rwsem);
247 ret = notifier_chain_cond_register(&nh->head, n);
248 up_write(&nh->rwsem);
249 return ret;
250}
251EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register);
252
253/**
254 * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
255 * @nh: Pointer to head of the blocking notifier chain
256 * @n: Entry to remove from notifier chain
257 *
258 * Removes a notifier from a blocking notifier chain.
259 * Must be called from process context.
260 *
261 * Returns zero on success or %-ENOENT on failure.
262 */
263int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
264 struct notifier_block *n)
265{
266 int ret;
267
268 /*
269 * This code gets used during boot-up, when task switching is
270 * not yet working and interrupts must remain disabled. At
271 * such times we must not call down_write().
272 */
273 if (unlikely(system_state == SYSTEM_BOOTING))
274 return notifier_chain_unregister(&nh->head, n);
275
276 down_write(&nh->rwsem);
277 ret = notifier_chain_unregister(&nh->head, n);
278 up_write(&nh->rwsem);
279 return ret;
280}
281EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
282
283/**
284 * __blocking_notifier_call_chain - Call functions in a blocking notifier chain
285 * @nh: Pointer to head of the blocking notifier chain
286 * @val: Value passed unmodified to notifier function
287 * @v: Pointer passed unmodified to notifier function
288 * @nr_to_call: See comment for notifier_call_chain.
289 * @nr_calls: See comment for notifier_call_chain.
290 *
291 * Calls each function in a notifier chain in turn. The functions
292 * run in a process context, so they are allowed to block.
293 *
294 * If the return value of the notifier can be and'ed
295 * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
296 * will return immediately, with the return value of
297 * the notifier function which halted execution.
298 * Otherwise the return value is the return value
299 * of the last notifier function called.
300 */
301int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
302 unsigned long val, void *v,
303 int nr_to_call, int *nr_calls)
304{
305 int ret = NOTIFY_DONE;
306
307 /*
308 * We check the head outside the lock, but if this access is
309 * racy then it does not matter what the result of the test
310 * is, we re-check the list after having taken the lock anyway:
311 */
312 if (rcu_dereference_raw(nh->head)) {
313 down_read(&nh->rwsem);
314 ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
315 nr_calls);
316 up_read(&nh->rwsem);
317 }
318 return ret;
319}
320EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
321
322int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
323 unsigned long val, void *v)
324{
325 return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
326}
327EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
328
329/*
330 * Raw notifier chain routines. There is no protection;
331 * the caller must provide it. Use at your own risk!
332 */
333
334/**
335 * raw_notifier_chain_register - Add notifier to a raw notifier chain
336 * @nh: Pointer to head of the raw notifier chain
337 * @n: New entry in notifier chain
338 *
339 * Adds a notifier to a raw notifier chain.
340 * All locking must be provided by the caller.
341 *
342 * Currently always returns zero.
343 */
344int raw_notifier_chain_register(struct raw_notifier_head *nh,
345 struct notifier_block *n)
346{
347 return notifier_chain_register(&nh->head, n);
348}
349EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
350
351/**
352 * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
353 * @nh: Pointer to head of the raw notifier chain
354 * @n: Entry to remove from notifier chain
355 *
356 * Removes a notifier from a raw notifier chain.
357 * All locking must be provided by the caller.
358 *
359 * Returns zero on success or %-ENOENT on failure.
360 */
361int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
362 struct notifier_block *n)
363{
364 return notifier_chain_unregister(&nh->head, n);
365}
366EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
367
368/**
369 * __raw_notifier_call_chain - Call functions in a raw notifier chain
370 * @nh: Pointer to head of the raw notifier chain
371 * @val: Value passed unmodified to notifier function
372 * @v: Pointer passed unmodified to notifier function
373 * @nr_to_call: See comment for notifier_call_chain.
374 * @nr_calls: See comment for notifier_call_chain
375 *
376 * Calls each function in a notifier chain in turn. The functions
377 * run in an undefined context.
378 * All locking must be provided by the caller.
379 *
380 * If the return value of the notifier can be and'ed
381 * with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
382 * will return immediately, with the return value of
383 * the notifier function which halted execution.
384 * Otherwise the return value is the return value
385 * of the last notifier function called.
386 */
387int __raw_notifier_call_chain(struct raw_notifier_head *nh,
388 unsigned long val, void *v,
389 int nr_to_call, int *nr_calls)
390{
391 return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
392}
393EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
394
395int raw_notifier_call_chain(struct raw_notifier_head *nh,
396 unsigned long val, void *v)
397{
398 return __raw_notifier_call_chain(nh, val, v, -1, NULL);
399}
400EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
401
402/*
403 * SRCU notifier chain routines. Registration and unregistration
404 * use a mutex, and call_chain is synchronized by SRCU (no locks).
405 */
406
407/**
408 * srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
409 * @nh: Pointer to head of the SRCU notifier chain
410 * @n: New entry in notifier chain
411 *
412 * Adds a notifier to an SRCU notifier chain.
413 * Must be called in process context.
414 *
415 * Currently always returns zero.
416 */
417int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
418 struct notifier_block *n)
419{
420 int ret;
421
422 /*
423 * This code gets used during boot-up, when task switching is
424 * not yet working and interrupts must remain disabled. At
425 * such times we must not call mutex_lock().
426 */
427 if (unlikely(system_state == SYSTEM_BOOTING))
428 return notifier_chain_register(&nh->head, n);
429
430 mutex_lock(&nh->mutex);
431 ret = notifier_chain_register(&nh->head, n);
432 mutex_unlock(&nh->mutex);
433 return ret;
434}
435EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
436
437/**
438 * srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
439 * @nh: Pointer to head of the SRCU notifier chain
440 * @n: Entry to remove from notifier chain
441 *
442 * Removes a notifier from an SRCU notifier chain.
443 * Must be called from process context.
444 *
445 * Returns zero on success or %-ENOENT on failure.
446 */
447int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
448 struct notifier_block *n)
449{
450 int ret;
451
452 /*
453 * This code gets used during boot-up, when task switching is
454 * not yet working and interrupts must remain disabled. At
455 * such times we must not call mutex_lock().
456 */
457 if (unlikely(system_state == SYSTEM_BOOTING))
458 return notifier_chain_unregister(&nh->head, n);
459
460 mutex_lock(&nh->mutex);
461 ret = notifier_chain_unregister(&nh->head, n);
462 mutex_unlock(&nh->mutex);
463 synchronize_srcu(&nh->srcu);
464 return ret;
465}
466EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
467
468/**
469 * __srcu_notifier_call_chain - Call functions in an SRCU notifier chain
470 * @nh: Pointer to head of the SRCU notifier chain
471 * @val: Value passed unmodified to notifier function
472 * @v: Pointer passed unmodified to notifier function
473 * @nr_to_call: See comment for notifier_call_chain.
474 * @nr_calls: See comment for notifier_call_chain
475 *
476 * Calls each function in a notifier chain in turn. The functions
477 * run in a process context, so they are allowed to block.
478 *
479 * If the return value of the notifier can be and'ed
480 * with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
481 * will return immediately, with the return value of
482 * the notifier function which halted execution.
483 * Otherwise the return value is the return value
484 * of the last notifier function called.
485 */
486int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
487 unsigned long val, void *v,
488 int nr_to_call, int *nr_calls)
489{
490 int ret;
491 int idx;
492
493 idx = srcu_read_lock(&nh->srcu);
494 ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
495 srcu_read_unlock(&nh->srcu, idx);
496 return ret;
497}
498EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain);
499
500int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
501 unsigned long val, void *v)
502{
503 return __srcu_notifier_call_chain(nh, val, v, -1, NULL);
504}
505EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
506
507/**
508 * srcu_init_notifier_head - Initialize an SRCU notifier head
509 * @nh: Pointer to head of the srcu notifier chain
510 *
511 * Unlike other sorts of notifier heads, SRCU notifier heads require
512 * dynamic initialization. Be sure to call this routine before
513 * calling any of the other SRCU notifier routines for this head.
514 *
515 * If an SRCU notifier head is deallocated, it must first be cleaned
516 * up by calling srcu_cleanup_notifier_head(). Otherwise the head's
517 * per-cpu data (used by the SRCU mechanism) will leak.
518 */
519void srcu_init_notifier_head(struct srcu_notifier_head *nh)
520{
521 mutex_init(&nh->mutex);
522 if (init_srcu_struct(&nh->srcu) < 0)
523 BUG();
524 nh->head = NULL;
525}
526EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
527
528static ATOMIC_NOTIFIER_HEAD(die_chain);
529
530int notrace __kprobes notify_die(enum die_val val, const char *str,
531 struct pt_regs *regs, long err, int trap, int sig)
532{
533 struct die_args args = {
534 .regs = regs,
535 .str = str,
536 .err = err,
537 .trapnr = trap,
538 .signr = sig,
539
540 };
541 return atomic_notifier_call_chain(&die_chain, val, &args);
542}
543
544int register_die_notifier(struct notifier_block *nb)
545{
546 vmalloc_sync_all();
547 return atomic_notifier_chain_register(&die_chain, nb);
548}
549EXPORT_SYMBOL_GPL(register_die_notifier);
550
551int unregister_die_notifier(struct notifier_block *nb)
552{
553 return atomic_notifier_chain_unregister(&die_chain, nb);
554}
555EXPORT_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#define CREATE_TRACE_POINTS
11#include <trace/events/notifier.h>
12
13/*
14 * Notifier list for kernel code which wants to be called
15 * at shutdown. This is used to stop any idling DMA operations
16 * and the like.
17 */
18BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
19
20/*
21 * Notifier chain core routines. The exported routines below
22 * are layered on top of these, with appropriate locking added.
23 */
24
25static int notifier_chain_register(struct notifier_block **nl,
26 struct notifier_block *n,
27 bool unique_priority)
28{
29 while ((*nl) != NULL) {
30 if (unlikely((*nl) == n)) {
31 WARN(1, "notifier callback %ps already registered",
32 n->notifier_call);
33 return -EEXIST;
34 }
35 if (n->priority > (*nl)->priority)
36 break;
37 if (n->priority == (*nl)->priority && unique_priority)
38 return -EBUSY;
39 nl = &((*nl)->next);
40 }
41 n->next = *nl;
42 rcu_assign_pointer(*nl, n);
43 trace_notifier_register((void *)n->notifier_call);
44 return 0;
45}
46
47static int notifier_chain_unregister(struct notifier_block **nl,
48 struct notifier_block *n)
49{
50 while ((*nl) != NULL) {
51 if ((*nl) == n) {
52 rcu_assign_pointer(*nl, n->next);
53 trace_notifier_unregister((void *)n->notifier_call);
54 return 0;
55 }
56 nl = &((*nl)->next);
57 }
58 return -ENOENT;
59}
60
61/**
62 * notifier_call_chain - Informs the registered notifiers about an event.
63 * @nl: Pointer to head of the blocking notifier chain
64 * @val: Value passed unmodified to notifier function
65 * @v: Pointer passed unmodified to notifier function
66 * @nr_to_call: Number of notifier functions to be called. Don't care
67 * value of this parameter is -1.
68 * @nr_calls: Records the number of notifications sent. Don't care
69 * value of this field is NULL.
70 * Return: notifier_call_chain returns the value returned by the
71 * last notifier function called.
72 */
73static int notifier_call_chain(struct notifier_block **nl,
74 unsigned long val, void *v,
75 int nr_to_call, int *nr_calls)
76{
77 int ret = NOTIFY_DONE;
78 struct notifier_block *nb, *next_nb;
79
80 nb = rcu_dereference_raw(*nl);
81
82 while (nb && nr_to_call) {
83 next_nb = rcu_dereference_raw(nb->next);
84
85#ifdef CONFIG_DEBUG_NOTIFIERS
86 if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
87 WARN(1, "Invalid notifier called!");
88 nb = next_nb;
89 continue;
90 }
91#endif
92 trace_notifier_run((void *)nb->notifier_call);
93 ret = nb->notifier_call(nb, val, v);
94
95 if (nr_calls)
96 (*nr_calls)++;
97
98 if (ret & 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 * notifier_call_chain_robust - Inform the registered notifiers about an event
109 * and rollback on error.
110 * @nl: Pointer to head of the blocking notifier chain
111 * @val_up: Value passed unmodified to the notifier function
112 * @val_down: Value passed unmodified to the notifier function when recovering
113 * from an error on @val_up
114 * @v: Pointer passed unmodified to the notifier function
115 *
116 * NOTE: It is important the @nl chain doesn't change between the two
117 * invocations of notifier_call_chain() such that we visit the
118 * exact same notifier callbacks; this rules out any RCU usage.
119 *
120 * Return: the return value of the @val_up call.
121 */
122static int notifier_call_chain_robust(struct notifier_block **nl,
123 unsigned long val_up, unsigned long val_down,
124 void *v)
125{
126 int ret, nr = 0;
127
128 ret = notifier_call_chain(nl, val_up, v, -1, &nr);
129 if (ret & NOTIFY_STOP_MASK)
130 notifier_call_chain(nl, val_down, v, nr-1, NULL);
131
132 return ret;
133}
134
135/*
136 * Atomic notifier chain routines. Registration and unregistration
137 * use a spinlock, and call_chain is synchronized by RCU (no locks).
138 */
139
140/**
141 * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
142 * @nh: Pointer to head of the atomic notifier chain
143 * @n: New entry in notifier chain
144 *
145 * Adds a notifier to an atomic notifier chain.
146 *
147 * Returns 0 on success, %-EEXIST on error.
148 */
149int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
150 struct notifier_block *n)
151{
152 unsigned long flags;
153 int ret;
154
155 spin_lock_irqsave(&nh->lock, flags);
156 ret = notifier_chain_register(&nh->head, n, false);
157 spin_unlock_irqrestore(&nh->lock, flags);
158 return ret;
159}
160EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
161
162/**
163 * atomic_notifier_chain_register_unique_prio - Add notifier to an atomic notifier chain
164 * @nh: Pointer to head of the atomic notifier chain
165 * @n: New entry in notifier chain
166 *
167 * Adds a notifier to an atomic notifier chain if there is no other
168 * notifier registered using the same priority.
169 *
170 * Returns 0 on success, %-EEXIST or %-EBUSY on error.
171 */
172int atomic_notifier_chain_register_unique_prio(struct atomic_notifier_head *nh,
173 struct notifier_block *n)
174{
175 unsigned long flags;
176 int ret;
177
178 spin_lock_irqsave(&nh->lock, flags);
179 ret = notifier_chain_register(&nh->head, n, true);
180 spin_unlock_irqrestore(&nh->lock, flags);
181 return ret;
182}
183EXPORT_SYMBOL_GPL(atomic_notifier_chain_register_unique_prio);
184
185/**
186 * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
187 * @nh: Pointer to head of the atomic notifier chain
188 * @n: Entry to remove from notifier chain
189 *
190 * Removes a notifier from an atomic notifier chain.
191 *
192 * Returns zero on success or %-ENOENT on failure.
193 */
194int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
195 struct notifier_block *n)
196{
197 unsigned long flags;
198 int ret;
199
200 spin_lock_irqsave(&nh->lock, flags);
201 ret = notifier_chain_unregister(&nh->head, n);
202 spin_unlock_irqrestore(&nh->lock, flags);
203 synchronize_rcu();
204 return ret;
205}
206EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
207
208/**
209 * atomic_notifier_call_chain - Call functions in an atomic notifier chain
210 * @nh: Pointer to head of the atomic notifier chain
211 * @val: Value passed unmodified to notifier function
212 * @v: Pointer passed unmodified to notifier function
213 *
214 * Calls each function in a notifier chain in turn. The functions
215 * run in an atomic context, so they must not block.
216 * This routine uses RCU to synchronize with changes to the chain.
217 *
218 * If the return value of the notifier can be and'ed
219 * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
220 * will return immediately, with the return value of
221 * the notifier function which halted execution.
222 * Otherwise the return value is the return value
223 * of the last notifier function called.
224 */
225int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
226 unsigned long val, void *v)
227{
228 int ret;
229
230 rcu_read_lock();
231 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
232 rcu_read_unlock();
233
234 return ret;
235}
236EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
237NOKPROBE_SYMBOL(atomic_notifier_call_chain);
238
239/**
240 * atomic_notifier_call_chain_is_empty - Check whether notifier chain is empty
241 * @nh: Pointer to head of the atomic notifier chain
242 *
243 * Checks whether notifier chain is empty.
244 *
245 * Returns true is notifier chain is empty, false otherwise.
246 */
247bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh)
248{
249 return !rcu_access_pointer(nh->head);
250}
251
252/*
253 * Blocking notifier chain routines. All access to the chain is
254 * synchronized by an rwsem.
255 */
256
257static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
258 struct notifier_block *n,
259 bool unique_priority)
260{
261 int ret;
262
263 /*
264 * This code gets used during boot-up, when task switching is
265 * not yet working and interrupts must remain disabled. At
266 * such times we must not call down_write().
267 */
268 if (unlikely(system_state == SYSTEM_BOOTING))
269 return notifier_chain_register(&nh->head, n, unique_priority);
270
271 down_write(&nh->rwsem);
272 ret = notifier_chain_register(&nh->head, n, unique_priority);
273 up_write(&nh->rwsem);
274 return ret;
275}
276
277/**
278 * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
279 * @nh: Pointer to head of the blocking notifier chain
280 * @n: New entry in notifier chain
281 *
282 * Adds a notifier to a blocking notifier chain.
283 * Must be called in process context.
284 *
285 * Returns 0 on success, %-EEXIST on error.
286 */
287int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
288 struct notifier_block *n)
289{
290 return __blocking_notifier_chain_register(nh, n, false);
291}
292EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
293
294/**
295 * blocking_notifier_chain_register_unique_prio - Add notifier to a blocking notifier chain
296 * @nh: Pointer to head of the blocking notifier chain
297 * @n: New entry in notifier chain
298 *
299 * Adds a notifier to an blocking notifier chain if there is no other
300 * notifier registered using the same priority.
301 *
302 * Returns 0 on success, %-EEXIST or %-EBUSY on error.
303 */
304int blocking_notifier_chain_register_unique_prio(struct blocking_notifier_head *nh,
305 struct notifier_block *n)
306{
307 return __blocking_notifier_chain_register(nh, n, true);
308}
309EXPORT_SYMBOL_GPL(blocking_notifier_chain_register_unique_prio);
310
311/**
312 * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
313 * @nh: Pointer to head of the blocking notifier chain
314 * @n: Entry to remove from notifier chain
315 *
316 * Removes a notifier from a blocking notifier chain.
317 * Must be called from process context.
318 *
319 * Returns zero on success or %-ENOENT on failure.
320 */
321int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
322 struct notifier_block *n)
323{
324 int ret;
325
326 /*
327 * This code gets used during boot-up, when task switching is
328 * not yet working and interrupts must remain disabled. At
329 * such times we must not call down_write().
330 */
331 if (unlikely(system_state == SYSTEM_BOOTING))
332 return notifier_chain_unregister(&nh->head, n);
333
334 down_write(&nh->rwsem);
335 ret = notifier_chain_unregister(&nh->head, n);
336 up_write(&nh->rwsem);
337 return ret;
338}
339EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
340
341int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh,
342 unsigned long val_up, unsigned long val_down, void *v)
343{
344 int ret = NOTIFY_DONE;
345
346 /*
347 * We check the head outside the lock, but if this access is
348 * racy then it does not matter what the result of the test
349 * is, we re-check the list after having taken the lock anyway:
350 */
351 if (rcu_access_pointer(nh->head)) {
352 down_read(&nh->rwsem);
353 ret = notifier_call_chain_robust(&nh->head, val_up, val_down, v);
354 up_read(&nh->rwsem);
355 }
356 return ret;
357}
358EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_robust);
359
360/**
361 * blocking_notifier_call_chain - Call functions in a blocking notifier chain
362 * @nh: Pointer to head of the blocking notifier chain
363 * @val: Value passed unmodified to notifier function
364 * @v: Pointer passed unmodified to notifier function
365 *
366 * Calls each function in a notifier chain in turn. The functions
367 * run in a process context, so they are allowed to block.
368 *
369 * If the return value of the notifier can be and'ed
370 * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
371 * will return immediately, with the return value of
372 * the notifier function which halted execution.
373 * Otherwise the return value is the return value
374 * of the last notifier function called.
375 */
376int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
377 unsigned long val, void *v)
378{
379 int ret = NOTIFY_DONE;
380
381 /*
382 * We check the head outside the lock, but if this access is
383 * racy then it does not matter what the result of the test
384 * is, we re-check the list after having taken the lock anyway:
385 */
386 if (rcu_access_pointer(nh->head)) {
387 down_read(&nh->rwsem);
388 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
389 up_read(&nh->rwsem);
390 }
391 return ret;
392}
393EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
394
395/*
396 * Raw notifier chain routines. There is no protection;
397 * the caller must provide it. Use at your own risk!
398 */
399
400/**
401 * raw_notifier_chain_register - Add notifier to a raw notifier chain
402 * @nh: Pointer to head of the raw notifier chain
403 * @n: New entry in notifier chain
404 *
405 * Adds a notifier to a raw notifier chain.
406 * All locking must be provided by the caller.
407 *
408 * Returns 0 on success, %-EEXIST on error.
409 */
410int raw_notifier_chain_register(struct raw_notifier_head *nh,
411 struct notifier_block *n)
412{
413 return notifier_chain_register(&nh->head, n, false);
414}
415EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
416
417/**
418 * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
419 * @nh: Pointer to head of the raw notifier chain
420 * @n: Entry to remove from notifier chain
421 *
422 * Removes a notifier from a raw notifier chain.
423 * All locking must be provided by the caller.
424 *
425 * Returns zero on success or %-ENOENT on failure.
426 */
427int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
428 struct notifier_block *n)
429{
430 return notifier_chain_unregister(&nh->head, n);
431}
432EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
433
434int raw_notifier_call_chain_robust(struct raw_notifier_head *nh,
435 unsigned long val_up, unsigned long val_down, void *v)
436{
437 return notifier_call_chain_robust(&nh->head, val_up, val_down, v);
438}
439EXPORT_SYMBOL_GPL(raw_notifier_call_chain_robust);
440
441/**
442 * raw_notifier_call_chain - Call functions in a raw notifier chain
443 * @nh: Pointer to head of the raw notifier chain
444 * @val: Value passed unmodified to notifier function
445 * @v: Pointer passed unmodified to notifier function
446 *
447 * Calls each function in a notifier chain in turn. The functions
448 * run in an undefined context.
449 * All locking must be provided by the caller.
450 *
451 * If the return value of the notifier can be and'ed
452 * with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
453 * will return immediately, with the return value of
454 * the notifier function which halted execution.
455 * Otherwise the return value is the return value
456 * of the last notifier function called.
457 */
458int raw_notifier_call_chain(struct raw_notifier_head *nh,
459 unsigned long val, void *v)
460{
461 return notifier_call_chain(&nh->head, val, v, -1, NULL);
462}
463EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
464
465/*
466 * SRCU notifier chain routines. Registration and unregistration
467 * use a mutex, and call_chain is synchronized by SRCU (no locks).
468 */
469
470/**
471 * srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
472 * @nh: Pointer to head of the SRCU notifier chain
473 * @n: New entry in notifier chain
474 *
475 * Adds a notifier to an SRCU notifier chain.
476 * Must be called in process context.
477 *
478 * Returns 0 on success, %-EEXIST on error.
479 */
480int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
481 struct notifier_block *n)
482{
483 int ret;
484
485 /*
486 * This code gets used during boot-up, when task switching is
487 * not yet working and interrupts must remain disabled. At
488 * such times we must not call mutex_lock().
489 */
490 if (unlikely(system_state == SYSTEM_BOOTING))
491 return notifier_chain_register(&nh->head, n, false);
492
493 mutex_lock(&nh->mutex);
494 ret = notifier_chain_register(&nh->head, n, false);
495 mutex_unlock(&nh->mutex);
496 return ret;
497}
498EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
499
500/**
501 * srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
502 * @nh: Pointer to head of the SRCU notifier chain
503 * @n: Entry to remove from notifier chain
504 *
505 * Removes a notifier from an SRCU notifier chain.
506 * Must be called from process context.
507 *
508 * Returns zero on success or %-ENOENT on failure.
509 */
510int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
511 struct notifier_block *n)
512{
513 int ret;
514
515 /*
516 * This code gets used during boot-up, when task switching is
517 * not yet working and interrupts must remain disabled. At
518 * such times we must not call mutex_lock().
519 */
520 if (unlikely(system_state == SYSTEM_BOOTING))
521 return notifier_chain_unregister(&nh->head, n);
522
523 mutex_lock(&nh->mutex);
524 ret = notifier_chain_unregister(&nh->head, n);
525 mutex_unlock(&nh->mutex);
526 synchronize_srcu(&nh->srcu);
527 return ret;
528}
529EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
530
531/**
532 * srcu_notifier_call_chain - Call functions in an SRCU notifier chain
533 * @nh: Pointer to head of the SRCU notifier chain
534 * @val: Value passed unmodified to notifier function
535 * @v: Pointer passed unmodified to notifier function
536 *
537 * Calls each function in a notifier chain in turn. The functions
538 * run in a process context, so they are allowed to block.
539 *
540 * If the return value of the notifier can be and'ed
541 * with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
542 * will return immediately, with the return value of
543 * the notifier function which halted execution.
544 * Otherwise the return value is the return value
545 * of the last notifier function called.
546 */
547int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
548 unsigned long val, void *v)
549{
550 int ret;
551 int idx;
552
553 idx = srcu_read_lock(&nh->srcu);
554 ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
555 srcu_read_unlock(&nh->srcu, idx);
556 return ret;
557}
558EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
559
560/**
561 * srcu_init_notifier_head - Initialize an SRCU notifier head
562 * @nh: Pointer to head of the srcu notifier chain
563 *
564 * Unlike other sorts of notifier heads, SRCU notifier heads require
565 * dynamic initialization. Be sure to call this routine before
566 * calling any of the other SRCU notifier routines for this head.
567 *
568 * If an SRCU notifier head is deallocated, it must first be cleaned
569 * up by calling srcu_cleanup_notifier_head(). Otherwise the head's
570 * per-cpu data (used by the SRCU mechanism) will leak.
571 */
572void srcu_init_notifier_head(struct srcu_notifier_head *nh)
573{
574 mutex_init(&nh->mutex);
575 if (init_srcu_struct(&nh->srcu) < 0)
576 BUG();
577 nh->head = NULL;
578}
579EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
580
581static ATOMIC_NOTIFIER_HEAD(die_chain);
582
583int notrace notify_die(enum die_val val, const char *str,
584 struct pt_regs *regs, long err, int trap, int sig)
585{
586 struct die_args args = {
587 .regs = regs,
588 .str = str,
589 .err = err,
590 .trapnr = trap,
591 .signr = sig,
592
593 };
594 RCU_LOCKDEP_WARN(!rcu_is_watching(),
595 "notify_die called but RCU thinks we're quiescent");
596 return atomic_notifier_call_chain(&die_chain, val, &args);
597}
598NOKPROBE_SYMBOL(notify_die);
599
600int register_die_notifier(struct notifier_block *nb)
601{
602 return atomic_notifier_chain_register(&die_chain, nb);
603}
604EXPORT_SYMBOL_GPL(register_die_notifier);
605
606int unregister_die_notifier(struct notifier_block *nb)
607{
608 return atomic_notifier_chain_unregister(&die_chain, nb);
609}
610EXPORT_SYMBOL_GPL(unregister_die_notifier);