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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#include <linux/kdebug.h>
2#include <linux/kprobes.h>
3#include <linux/module.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);