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9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/sched/signal.h>
12#include <linux/fs.h>
13#include <linux/file.h>
14#include <linux/signal.h>
15#include <linux/errno.h>
16#include <linux/mm.h>
17#include <linux/slab.h>
18#include <linux/poll.h>
19#include <linux/string.h>
20#include <linux/list.h>
21#include <linux/hash.h>
22#include <linux/spinlock.h>
23#include <linux/syscalls.h>
24#include <linux/rbtree.h>
25#include <linux/wait.h>
26#include <linux/eventpoll.h>
27#include <linux/mount.h>
28#include <linux/bitops.h>
29#include <linux/mutex.h>
30#include <linux/anon_inodes.h>
31#include <linux/device.h>
32#include <linux/uaccess.h>
33#include <asm/io.h>
34#include <asm/mman.h>
35#include <linux/atomic.h>
36#include <linux/proc_fs.h>
37#include <linux/seq_file.h>
38#include <linux/compat.h>
39#include <linux/rculist.h>
40#include <net/busy_poll.h>
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90
91#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET | EPOLLEXCLUSIVE)
92
93#define EPOLLINOUT_BITS (EPOLLIN | EPOLLOUT)
94
95#define EPOLLEXCLUSIVE_OK_BITS (EPOLLINOUT_BITS | EPOLLERR | EPOLLHUP | \
96 EPOLLWAKEUP | EPOLLET | EPOLLEXCLUSIVE)
97
98
99#define EP_MAX_NESTS 4
100
101#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
102
103#define EP_UNACTIVE_PTR ((void *) -1L)
104
105#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
106
107struct epoll_filefd {
108 struct file *file;
109 int fd;
110} __packed;
111
112
113struct eppoll_entry {
114
115 struct eppoll_entry *next;
116
117
118 struct epitem *base;
119
120
121
122
123
124 wait_queue_entry_t wait;
125
126
127 wait_queue_head_t *whead;
128};
129
130
131
132
133
134
135
136struct epitem {
137 union {
138
139 struct rb_node rbn;
140
141 struct rcu_head rcu;
142 };
143
144
145 struct list_head rdllink;
146
147
148
149
150
151 struct epitem *next;
152
153
154 struct epoll_filefd ffd;
155
156
157 struct eppoll_entry *pwqlist;
158
159
160 struct eventpoll *ep;
161
162
163 struct hlist_node fllink;
164
165
166 struct wakeup_source __rcu *ws;
167
168
169 struct epoll_event event;
170};
171
172
173
174
175
176
177struct eventpoll {
178
179
180
181
182
183
184 struct mutex mtx;
185
186
187 wait_queue_head_t wq;
188
189
190 wait_queue_head_t poll_wait;
191
192
193 struct list_head rdllist;
194
195
196 rwlock_t lock;
197
198
199 struct rb_root_cached rbr;
200
201
202
203
204
205
206 struct epitem *ovflist;
207
208
209 struct wakeup_source *ws;
210
211
212 struct user_struct *user;
213
214 struct file *file;
215
216
217 u64 gen;
218 struct hlist_head refs;
219
220#ifdef CONFIG_NET_RX_BUSY_POLL
221
222 unsigned int napi_id;
223#endif
224
225#ifdef CONFIG_DEBUG_LOCK_ALLOC
226
227 u8 nests;
228#endif
229};
230
231
232struct ep_pqueue {
233 poll_table pt;
234 struct epitem *epi;
235};
236
237
238
239
240
241static long max_user_watches __read_mostly;
242
243
244
245
246static DEFINE_MUTEX(epmutex);
247
248static u64 loop_check_gen = 0;
249
250
251static struct eventpoll *inserting_into;
252
253
254static struct kmem_cache *epi_cache __read_mostly;
255
256
257static struct kmem_cache *pwq_cache __read_mostly;
258
259
260
261
262
263struct epitems_head {
264 struct hlist_head epitems;
265 struct epitems_head *next;
266};
267static struct epitems_head *tfile_check_list = EP_UNACTIVE_PTR;
268
269static struct kmem_cache *ephead_cache __read_mostly;
270
271static inline void free_ephead(struct epitems_head *head)
272{
273 if (head)
274 kmem_cache_free(ephead_cache, head);
275}
276
277static void list_file(struct file *file)
278{
279 struct epitems_head *head;
280
281 head = container_of(file->f_ep, struct epitems_head, epitems);
282 if (!head->next) {
283 head->next = tfile_check_list;
284 tfile_check_list = head;
285 }
286}
287
288static void unlist_file(struct epitems_head *head)
289{
290 struct epitems_head *to_free = head;
291 struct hlist_node *p = rcu_dereference(hlist_first_rcu(&head->epitems));
292 if (p) {
293 struct epitem *epi= container_of(p, struct epitem, fllink);
294 spin_lock(&epi->ffd.file->f_lock);
295 if (!hlist_empty(&head->epitems))
296 to_free = NULL;
297 head->next = NULL;
298 spin_unlock(&epi->ffd.file->f_lock);
299 }
300 free_ephead(to_free);
301}
302
303#ifdef CONFIG_SYSCTL
304
305#include <linux/sysctl.h>
306
307static long long_zero;
308static long long_max = LONG_MAX;
309
310struct ctl_table epoll_table[] = {
311 {
312 .procname = "max_user_watches",
313 .data = &max_user_watches,
314 .maxlen = sizeof(max_user_watches),
315 .mode = 0644,
316 .proc_handler = proc_doulongvec_minmax,
317 .extra1 = &long_zero,
318 .extra2 = &long_max,
319 },
320 { }
321};
322#endif
323
324static const struct file_operations eventpoll_fops;
325
326static inline int is_file_epoll(struct file *f)
327{
328 return f->f_op == &eventpoll_fops;
329}
330
331
332static inline void ep_set_ffd(struct epoll_filefd *ffd,
333 struct file *file, int fd)
334{
335 ffd->file = file;
336 ffd->fd = fd;
337}
338
339
340static inline int ep_cmp_ffd(struct epoll_filefd *p1,
341 struct epoll_filefd *p2)
342{
343 return (p1->file > p2->file ? +1:
344 (p1->file < p2->file ? -1 : p1->fd - p2->fd));
345}
346
347
348static inline int ep_is_linked(struct epitem *epi)
349{
350 return !list_empty(&epi->rdllink);
351}
352
353static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_entry_t *p)
354{
355 return container_of(p, struct eppoll_entry, wait);
356}
357
358
359static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p)
360{
361 return container_of(p, struct eppoll_entry, wait)->base;
362}
363
364
365
366
367
368
369
370
371
372static inline int ep_events_available(struct eventpoll *ep)
373{
374 return !list_empty_careful(&ep->rdllist) ||
375 READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR;
376}
377
378#ifdef CONFIG_NET_RX_BUSY_POLL
379static bool ep_busy_loop_end(void *p, unsigned long start_time)
380{
381 struct eventpoll *ep = p;
382
383 return ep_events_available(ep) || busy_loop_timeout(start_time);
384}
385
386
387
388
389
390
391
392static bool ep_busy_loop(struct eventpoll *ep, int nonblock)
393{
394 unsigned int napi_id = READ_ONCE(ep->napi_id);
395
396 if ((napi_id >= MIN_NAPI_ID) && net_busy_loop_on()) {
397 napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false,
398 BUSY_POLL_BUDGET);
399 if (ep_events_available(ep))
400 return true;
401
402
403
404
405
406 ep->napi_id = 0;
407 return false;
408 }
409 return false;
410}
411
412
413
414
415static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
416{
417 struct eventpoll *ep;
418 unsigned int napi_id;
419 struct socket *sock;
420 struct sock *sk;
421
422 if (!net_busy_loop_on())
423 return;
424
425 sock = sock_from_file(epi->ffd.file);
426 if (!sock)
427 return;
428
429 sk = sock->sk;
430 if (!sk)
431 return;
432
433 napi_id = READ_ONCE(sk->sk_napi_id);
434 ep = epi->ep;
435
436
437
438
439
440 if (napi_id < MIN_NAPI_ID || napi_id == ep->napi_id)
441 return;
442
443
444 ep->napi_id = napi_id;
445}
446
447#else
448
449static inline bool ep_busy_loop(struct eventpoll *ep, int nonblock)
450{
451 return false;
452}
453
454static inline void ep_set_busy_poll_napi_id(struct epitem *epi)
455{
456}
457
458#endif
459
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484
485#ifdef CONFIG_DEBUG_LOCK_ALLOC
486
487static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
488{
489 struct eventpoll *ep_src;
490 unsigned long flags;
491 u8 nests = 0;
492
493
494
495
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505
506
507
508 if (epi) {
509 if ((is_file_epoll(epi->ffd.file))) {
510 ep_src = epi->ffd.file->private_data;
511 nests = ep_src->nests;
512 } else {
513 nests = 1;
514 }
515 }
516 spin_lock_irqsave_nested(&ep->poll_wait.lock, flags, nests);
517 ep->nests = nests + 1;
518 wake_up_locked_poll(&ep->poll_wait, EPOLLIN);
519 ep->nests = 0;
520 spin_unlock_irqrestore(&ep->poll_wait.lock, flags);
521}
522
523#else
524
525static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
526{
527 wake_up_poll(&ep->poll_wait, EPOLLIN);
528}
529
530#endif
531
532static void ep_remove_wait_queue(struct eppoll_entry *pwq)
533{
534 wait_queue_head_t *whead;
535
536 rcu_read_lock();
537
538
539
540
541
542
543 whead = smp_load_acquire(&pwq->whead);
544 if (whead)
545 remove_wait_queue(whead, &pwq->wait);
546 rcu_read_unlock();
547}
548
549
550
551
552
553
554static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
555{
556 struct eppoll_entry **p = &epi->pwqlist;
557 struct eppoll_entry *pwq;
558
559 while ((pwq = *p) != NULL) {
560 *p = pwq->next;
561 ep_remove_wait_queue(pwq);
562 kmem_cache_free(pwq_cache, pwq);
563 }
564}
565
566
567static inline struct wakeup_source *ep_wakeup_source(struct epitem *epi)
568{
569 return rcu_dereference_check(epi->ws, lockdep_is_held(&epi->ep->mtx));
570}
571
572
573static inline void ep_pm_stay_awake(struct epitem *epi)
574{
575 struct wakeup_source *ws = ep_wakeup_source(epi);
576
577 if (ws)
578 __pm_stay_awake(ws);
579}
580
581static inline bool ep_has_wakeup_source(struct epitem *epi)
582{
583 return rcu_access_pointer(epi->ws) ? true : false;
584}
585
586
587static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
588{
589 struct wakeup_source *ws;
590
591 rcu_read_lock();
592 ws = rcu_dereference(epi->ws);
593 if (ws)
594 __pm_stay_awake(ws);
595 rcu_read_unlock();
596}
597
598
599
600
601
602
603static void ep_start_scan(struct eventpoll *ep, struct list_head *txlist)
604{
605
606
607
608
609
610
611
612
613 lockdep_assert_irqs_enabled();
614 write_lock_irq(&ep->lock);
615 list_splice_init(&ep->rdllist, txlist);
616 WRITE_ONCE(ep->ovflist, NULL);
617 write_unlock_irq(&ep->lock);
618}
619
620static void ep_done_scan(struct eventpoll *ep,
621 struct list_head *txlist)
622{
623 struct epitem *epi, *nepi;
624
625 write_lock_irq(&ep->lock);
626
627
628
629
630
631 for (nepi = READ_ONCE(ep->ovflist); (epi = nepi) != NULL;
632 nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
633
634
635
636
637
638
639 if (!ep_is_linked(epi)) {
640
641
642
643
644 list_add(&epi->rdllink, &ep->rdllist);
645 ep_pm_stay_awake(epi);
646 }
647 }
648
649
650
651
652
653 WRITE_ONCE(ep->ovflist, EP_UNACTIVE_PTR);
654
655
656
657
658 list_splice(txlist, &ep->rdllist);
659 __pm_relax(ep->ws);
660
661 if (!list_empty(&ep->rdllist)) {
662 if (waitqueue_active(&ep->wq))
663 wake_up(&ep->wq);
664 }
665
666 write_unlock_irq(&ep->lock);
667}
668
669static void epi_rcu_free(struct rcu_head *head)
670{
671 struct epitem *epi = container_of(head, struct epitem, rcu);
672 kmem_cache_free(epi_cache, epi);
673}
674
675
676
677
678
679static int ep_remove(struct eventpoll *ep, struct epitem *epi)
680{
681 struct file *file = epi->ffd.file;
682 struct epitems_head *to_free;
683 struct hlist_head *head;
684
685 lockdep_assert_irqs_enabled();
686
687
688
689
690 ep_unregister_pollwait(ep, epi);
691
692
693 spin_lock(&file->f_lock);
694 to_free = NULL;
695 head = file->f_ep;
696 if (head->first == &epi->fllink && !epi->fllink.next) {
697 file->f_ep = NULL;
698 if (!is_file_epoll(file)) {
699 struct epitems_head *v;
700 v = container_of(head, struct epitems_head, epitems);
701 if (!smp_load_acquire(&v->next))
702 to_free = v;
703 }
704 }
705 hlist_del_rcu(&epi->fllink);
706 spin_unlock(&file->f_lock);
707 free_ephead(to_free);
708
709 rb_erase_cached(&epi->rbn, &ep->rbr);
710
711 write_lock_irq(&ep->lock);
712 if (ep_is_linked(epi))
713 list_del_init(&epi->rdllink);
714 write_unlock_irq(&ep->lock);
715
716 wakeup_source_unregister(ep_wakeup_source(epi));
717
718
719
720
721
722
723
724 call_rcu(&epi->rcu, epi_rcu_free);
725
726 percpu_counter_dec(&ep->user->epoll_watches);
727
728 return 0;
729}
730
731static void ep_free(struct eventpoll *ep)
732{
733 struct rb_node *rbp;
734 struct epitem *epi;
735
736
737 if (waitqueue_active(&ep->poll_wait))
738 ep_poll_safewake(ep, NULL);
739
740
741
742
743
744
745
746
747
748 mutex_lock(&epmutex);
749
750
751
752
753 for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
754 epi = rb_entry(rbp, struct epitem, rbn);
755
756 ep_unregister_pollwait(ep, epi);
757 cond_resched();
758 }
759
760
761
762
763
764
765
766
767
768 mutex_lock(&ep->mtx);
769 while ((rbp = rb_first_cached(&ep->rbr)) != NULL) {
770 epi = rb_entry(rbp, struct epitem, rbn);
771 ep_remove(ep, epi);
772 cond_resched();
773 }
774 mutex_unlock(&ep->mtx);
775
776 mutex_unlock(&epmutex);
777 mutex_destroy(&ep->mtx);
778 free_uid(ep->user);
779 wakeup_source_unregister(ep->ws);
780 kfree(ep);
781}
782
783static int ep_eventpoll_release(struct inode *inode, struct file *file)
784{
785 struct eventpoll *ep = file->private_data;
786
787 if (ep)
788 ep_free(ep);
789
790 return 0;
791}
792
793static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt, int depth);
794
795static __poll_t __ep_eventpoll_poll(struct file *file, poll_table *wait, int depth)
796{
797 struct eventpoll *ep = file->private_data;
798 LIST_HEAD(txlist);
799 struct epitem *epi, *tmp;
800 poll_table pt;
801 __poll_t res = 0;
802
803 init_poll_funcptr(&pt, NULL);
804
805
806 poll_wait(file, &ep->poll_wait, wait);
807
808
809
810
811
812 mutex_lock_nested(&ep->mtx, depth);
813 ep_start_scan(ep, &txlist);
814 list_for_each_entry_safe(epi, tmp, &txlist, rdllink) {
815 if (ep_item_poll(epi, &pt, depth + 1)) {
816 res = EPOLLIN | EPOLLRDNORM;
817 break;
818 } else {
819
820
821
822
823
824 __pm_relax(ep_wakeup_source(epi));
825 list_del_init(&epi->rdllink);
826 }
827 }
828 ep_done_scan(ep, &txlist);
829 mutex_unlock(&ep->mtx);
830 return res;
831}
832
833
834
835
836
837
838static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt,
839 int depth)
840{
841 struct file *file = epi->ffd.file;
842 __poll_t res;
843
844 pt->_key = epi->event.events;
845 if (!is_file_epoll(file))
846 res = vfs_poll(file, pt);
847 else
848 res = __ep_eventpoll_poll(file, pt, depth);
849 return res & epi->event.events;
850}
851
852static __poll_t ep_eventpoll_poll(struct file *file, poll_table *wait)
853{
854 return __ep_eventpoll_poll(file, wait, 0);
855}
856
857#ifdef CONFIG_PROC_FS
858static void ep_show_fdinfo(struct seq_file *m, struct file *f)
859{
860 struct eventpoll *ep = f->private_data;
861 struct rb_node *rbp;
862
863 mutex_lock(&ep->mtx);
864 for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
865 struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
866 struct inode *inode = file_inode(epi->ffd.file);
867
868 seq_printf(m, "tfd: %8d events: %8x data: %16llx "
869 " pos:%lli ino:%lx sdev:%x\n",
870 epi->ffd.fd, epi->event.events,
871 (long long)epi->event.data,
872 (long long)epi->ffd.file->f_pos,
873 inode->i_ino, inode->i_sb->s_dev);
874 if (seq_has_overflowed(m))
875 break;
876 }
877 mutex_unlock(&ep->mtx);
878}
879#endif
880
881
882static const struct file_operations eventpoll_fops = {
883#ifdef CONFIG_PROC_FS
884 .show_fdinfo = ep_show_fdinfo,
885#endif
886 .release = ep_eventpoll_release,
887 .poll = ep_eventpoll_poll,
888 .llseek = noop_llseek,
889};
890
891
892
893
894
895
896void eventpoll_release_file(struct file *file)
897{
898 struct eventpoll *ep;
899 struct epitem *epi;
900 struct hlist_node *next;
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915 mutex_lock(&epmutex);
916 if (unlikely(!file->f_ep)) {
917 mutex_unlock(&epmutex);
918 return;
919 }
920 hlist_for_each_entry_safe(epi, next, file->f_ep, fllink) {
921 ep = epi->ep;
922 mutex_lock_nested(&ep->mtx, 0);
923 ep_remove(ep, epi);
924 mutex_unlock(&ep->mtx);
925 }
926 mutex_unlock(&epmutex);
927}
928
929static int ep_alloc(struct eventpoll **pep)
930{
931 int error;
932 struct user_struct *user;
933 struct eventpoll *ep;
934
935 user = get_current_user();
936 error = -ENOMEM;
937 ep = kzalloc(sizeof(*ep), GFP_KERNEL);
938 if (unlikely(!ep))
939 goto free_uid;
940
941 mutex_init(&ep->mtx);
942 rwlock_init(&ep->lock);
943 init_waitqueue_head(&ep->wq);
944 init_waitqueue_head(&ep->poll_wait);
945 INIT_LIST_HEAD(&ep->rdllist);
946 ep->rbr = RB_ROOT_CACHED;
947 ep->ovflist = EP_UNACTIVE_PTR;
948 ep->user = user;
949
950 *pep = ep;
951
952 return 0;
953
954free_uid:
955 free_uid(user);
956 return error;
957}
958
959
960
961
962
963
964static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
965{
966 int kcmp;
967 struct rb_node *rbp;
968 struct epitem *epi, *epir = NULL;
969 struct epoll_filefd ffd;
970
971 ep_set_ffd(&ffd, file, fd);
972 for (rbp = ep->rbr.rb_root.rb_node; rbp; ) {
973 epi = rb_entry(rbp, struct epitem, rbn);
974 kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
975 if (kcmp > 0)
976 rbp = rbp->rb_right;
977 else if (kcmp < 0)
978 rbp = rbp->rb_left;
979 else {
980 epir = epi;
981 break;
982 }
983 }
984
985 return epir;
986}
987
988#ifdef CONFIG_KCMP
989static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff)
990{
991 struct rb_node *rbp;
992 struct epitem *epi;
993
994 for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
995 epi = rb_entry(rbp, struct epitem, rbn);
996 if (epi->ffd.fd == tfd) {
997 if (toff == 0)
998 return epi;
999 else
1000 toff--;
1001 }
1002 cond_resched();
1003 }
1004
1005 return NULL;
1006}
1007
1008struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd,
1009 unsigned long toff)
1010{
1011 struct file *file_raw;
1012 struct eventpoll *ep;
1013 struct epitem *epi;
1014
1015 if (!is_file_epoll(file))
1016 return ERR_PTR(-EINVAL);
1017
1018 ep = file->private_data;
1019
1020 mutex_lock(&ep->mtx);
1021 epi = ep_find_tfd(ep, tfd, toff);
1022 if (epi)
1023 file_raw = epi->ffd.file;
1024 else
1025 file_raw = ERR_PTR(-ENOENT);
1026 mutex_unlock(&ep->mtx);
1027
1028 return file_raw;
1029}
1030#endif
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050static inline bool list_add_tail_lockless(struct list_head *new,
1051 struct list_head *head)
1052{
1053 struct list_head *prev;
1054
1055
1056
1057
1058
1059
1060
1061 if (cmpxchg(&new->next, new, head) != new)
1062 return false;
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072 prev = xchg(&head->prev, new);
1073
1074
1075
1076
1077
1078
1079 prev->next = new;
1080 new->prev = prev;
1081
1082 return true;
1083}
1084
1085
1086
1087
1088
1089
1090
1091static inline bool chain_epi_lockless(struct epitem *epi)
1092{
1093 struct eventpoll *ep = epi->ep;
1094
1095
1096 if (epi->next != EP_UNACTIVE_PTR)
1097 return false;
1098
1099
1100 if (cmpxchg(&epi->next, EP_UNACTIVE_PTR, NULL) != EP_UNACTIVE_PTR)
1101 return false;
1102
1103
1104 epi->next = xchg(&ep->ovflist, epi);
1105
1106 return true;
1107}
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
1128{
1129 int pwake = 0;
1130 struct epitem *epi = ep_item_from_wait(wait);
1131 struct eventpoll *ep = epi->ep;
1132 __poll_t pollflags = key_to_poll(key);
1133 unsigned long flags;
1134 int ewake = 0;
1135
1136 read_lock_irqsave(&ep->lock, flags);
1137
1138 ep_set_busy_poll_napi_id(epi);
1139
1140
1141
1142
1143
1144
1145
1146 if (!(epi->event.events & ~EP_PRIVATE_BITS))
1147 goto out_unlock;
1148
1149
1150
1151
1152
1153
1154
1155 if (pollflags && !(pollflags & epi->event.events))
1156 goto out_unlock;
1157
1158
1159
1160
1161
1162
1163
1164 if (READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR) {
1165 if (chain_epi_lockless(epi))
1166 ep_pm_stay_awake_rcu(epi);
1167 } else if (!ep_is_linked(epi)) {
1168
1169 if (list_add_tail_lockless(&epi->rdllink, &ep->rdllist))
1170 ep_pm_stay_awake_rcu(epi);
1171 }
1172
1173
1174
1175
1176
1177 if (waitqueue_active(&ep->wq)) {
1178 if ((epi->event.events & EPOLLEXCLUSIVE) &&
1179 !(pollflags & POLLFREE)) {
1180 switch (pollflags & EPOLLINOUT_BITS) {
1181 case EPOLLIN:
1182 if (epi->event.events & EPOLLIN)
1183 ewake = 1;
1184 break;
1185 case EPOLLOUT:
1186 if (epi->event.events & EPOLLOUT)
1187 ewake = 1;
1188 break;
1189 case 0:
1190 ewake = 1;
1191 break;
1192 }
1193 }
1194 wake_up(&ep->wq);
1195 }
1196 if (waitqueue_active(&ep->poll_wait))
1197 pwake++;
1198
1199out_unlock:
1200 read_unlock_irqrestore(&ep->lock, flags);
1201
1202
1203 if (pwake)
1204 ep_poll_safewake(ep, epi);
1205
1206 if (!(epi->event.events & EPOLLEXCLUSIVE))
1207 ewake = 1;
1208
1209 if (pollflags & POLLFREE) {
1210
1211
1212
1213
1214
1215 list_del_init(&wait->entry);
1216
1217
1218
1219
1220
1221
1222 smp_store_release(&ep_pwq_from_wait(wait)->whead, NULL);
1223 }
1224
1225 return ewake;
1226}
1227
1228
1229
1230
1231
1232static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
1233 poll_table *pt)
1234{
1235 struct ep_pqueue *epq = container_of(pt, struct ep_pqueue, pt);
1236 struct epitem *epi = epq->epi;
1237 struct eppoll_entry *pwq;
1238
1239 if (unlikely(!epi))
1240 return;
1241
1242 pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL);
1243 if (unlikely(!pwq)) {
1244 epq->epi = NULL;
1245 return;
1246 }
1247
1248 init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
1249 pwq->whead = whead;
1250 pwq->base = epi;
1251 if (epi->event.events & EPOLLEXCLUSIVE)
1252 add_wait_queue_exclusive(whead, &pwq->wait);
1253 else
1254 add_wait_queue(whead, &pwq->wait);
1255 pwq->next = epi->pwqlist;
1256 epi->pwqlist = pwq;
1257}
1258
1259static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
1260{
1261 int kcmp;
1262 struct rb_node **p = &ep->rbr.rb_root.rb_node, *parent = NULL;
1263 struct epitem *epic;
1264 bool leftmost = true;
1265
1266 while (*p) {
1267 parent = *p;
1268 epic = rb_entry(parent, struct epitem, rbn);
1269 kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
1270 if (kcmp > 0) {
1271 p = &parent->rb_right;
1272 leftmost = false;
1273 } else
1274 p = &parent->rb_left;
1275 }
1276 rb_link_node(&epi->rbn, parent, p);
1277 rb_insert_color_cached(&epi->rbn, &ep->rbr, leftmost);
1278}
1279
1280
1281
1282#define PATH_ARR_SIZE 5
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
1295static int path_count[PATH_ARR_SIZE];
1296
1297static int path_count_inc(int nests)
1298{
1299
1300 if (nests == 0)
1301 return 0;
1302
1303 if (++path_count[nests] > path_limits[nests])
1304 return -1;
1305 return 0;
1306}
1307
1308static void path_count_init(void)
1309{
1310 int i;
1311
1312 for (i = 0; i < PATH_ARR_SIZE; i++)
1313 path_count[i] = 0;
1314}
1315
1316static int reverse_path_check_proc(struct hlist_head *refs, int depth)
1317{
1318 int error = 0;
1319 struct epitem *epi;
1320
1321 if (depth > EP_MAX_NESTS)
1322 return -1;
1323
1324
1325 hlist_for_each_entry_rcu(epi, refs, fllink) {
1326 struct hlist_head *refs = &epi->ep->refs;
1327 if (hlist_empty(refs))
1328 error = path_count_inc(depth);
1329 else
1330 error = reverse_path_check_proc(refs, depth + 1);
1331 if (error != 0)
1332 break;
1333 }
1334 return error;
1335}
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347static int reverse_path_check(void)
1348{
1349 struct epitems_head *p;
1350
1351 for (p = tfile_check_list; p != EP_UNACTIVE_PTR; p = p->next) {
1352 int error;
1353 path_count_init();
1354 rcu_read_lock();
1355 error = reverse_path_check_proc(&p->epitems, 0);
1356 rcu_read_unlock();
1357 if (error)
1358 return error;
1359 }
1360 return 0;
1361}
1362
1363static int ep_create_wakeup_source(struct epitem *epi)
1364{
1365 struct name_snapshot n;
1366 struct wakeup_source *ws;
1367
1368 if (!epi->ep->ws) {
1369 epi->ep->ws = wakeup_source_register(NULL, "eventpoll");
1370 if (!epi->ep->ws)
1371 return -ENOMEM;
1372 }
1373
1374 take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
1375 ws = wakeup_source_register(NULL, n.name.name);
1376 release_dentry_name_snapshot(&n);
1377
1378 if (!ws)
1379 return -ENOMEM;
1380 rcu_assign_pointer(epi->ws, ws);
1381
1382 return 0;
1383}
1384
1385
1386static noinline void ep_destroy_wakeup_source(struct epitem *epi)
1387{
1388 struct wakeup_source *ws = ep_wakeup_source(epi);
1389
1390 RCU_INIT_POINTER(epi->ws, NULL);
1391
1392
1393
1394
1395
1396
1397 synchronize_rcu();
1398 wakeup_source_unregister(ws);
1399}
1400
1401static int attach_epitem(struct file *file, struct epitem *epi)
1402{
1403 struct epitems_head *to_free = NULL;
1404 struct hlist_head *head = NULL;
1405 struct eventpoll *ep = NULL;
1406
1407 if (is_file_epoll(file))
1408 ep = file->private_data;
1409
1410 if (ep) {
1411 head = &ep->refs;
1412 } else if (!READ_ONCE(file->f_ep)) {
1413allocate:
1414 to_free = kmem_cache_zalloc(ephead_cache, GFP_KERNEL);
1415 if (!to_free)
1416 return -ENOMEM;
1417 head = &to_free->epitems;
1418 }
1419 spin_lock(&file->f_lock);
1420 if (!file->f_ep) {
1421 if (unlikely(!head)) {
1422 spin_unlock(&file->f_lock);
1423 goto allocate;
1424 }
1425 file->f_ep = head;
1426 to_free = NULL;
1427 }
1428 hlist_add_head_rcu(&epi->fllink, file->f_ep);
1429 spin_unlock(&file->f_lock);
1430 free_ephead(to_free);
1431 return 0;
1432}
1433
1434
1435
1436
1437static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
1438 struct file *tfile, int fd, int full_check)
1439{
1440 int error, pwake = 0;
1441 __poll_t revents;
1442 struct epitem *epi;
1443 struct ep_pqueue epq;
1444 struct eventpoll *tep = NULL;
1445
1446 if (is_file_epoll(tfile))
1447 tep = tfile->private_data;
1448
1449 lockdep_assert_irqs_enabled();
1450
1451 if (unlikely(percpu_counter_compare(&ep->user->epoll_watches,
1452 max_user_watches) >= 0))
1453 return -ENOSPC;
1454 percpu_counter_inc(&ep->user->epoll_watches);
1455
1456 if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL))) {
1457 percpu_counter_dec(&ep->user->epoll_watches);
1458 return -ENOMEM;
1459 }
1460
1461
1462 INIT_LIST_HEAD(&epi->rdllink);
1463 epi->ep = ep;
1464 ep_set_ffd(&epi->ffd, tfile, fd);
1465 epi->event = *event;
1466 epi->next = EP_UNACTIVE_PTR;
1467
1468 if (tep)
1469 mutex_lock_nested(&tep->mtx, 1);
1470
1471 if (unlikely(attach_epitem(tfile, epi) < 0)) {
1472 if (tep)
1473 mutex_unlock(&tep->mtx);
1474 kmem_cache_free(epi_cache, epi);
1475 percpu_counter_dec(&ep->user->epoll_watches);
1476 return -ENOMEM;
1477 }
1478
1479 if (full_check && !tep)
1480 list_file(tfile);
1481
1482
1483
1484
1485
1486 ep_rbtree_insert(ep, epi);
1487 if (tep)
1488 mutex_unlock(&tep->mtx);
1489
1490
1491 if (unlikely(full_check && reverse_path_check())) {
1492 ep_remove(ep, epi);
1493 return -EINVAL;
1494 }
1495
1496 if (epi->event.events & EPOLLWAKEUP) {
1497 error = ep_create_wakeup_source(epi);
1498 if (error) {
1499 ep_remove(ep, epi);
1500 return error;
1501 }
1502 }
1503
1504
1505 epq.epi = epi;
1506 init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
1507
1508
1509
1510
1511
1512
1513
1514
1515 revents = ep_item_poll(epi, &epq.pt, 1);
1516
1517
1518
1519
1520
1521
1522 if (unlikely(!epq.epi)) {
1523 ep_remove(ep, epi);
1524 return -ENOMEM;
1525 }
1526
1527
1528 write_lock_irq(&ep->lock);
1529
1530
1531 ep_set_busy_poll_napi_id(epi);
1532
1533
1534 if (revents && !ep_is_linked(epi)) {
1535 list_add_tail(&epi->rdllink, &ep->rdllist);
1536 ep_pm_stay_awake(epi);
1537
1538
1539 if (waitqueue_active(&ep->wq))
1540 wake_up(&ep->wq);
1541 if (waitqueue_active(&ep->poll_wait))
1542 pwake++;
1543 }
1544
1545 write_unlock_irq(&ep->lock);
1546
1547
1548 if (pwake)
1549 ep_poll_safewake(ep, NULL);
1550
1551 return 0;
1552}
1553
1554
1555
1556
1557
1558static int ep_modify(struct eventpoll *ep, struct epitem *epi,
1559 const struct epoll_event *event)
1560{
1561 int pwake = 0;
1562 poll_table pt;
1563
1564 lockdep_assert_irqs_enabled();
1565
1566 init_poll_funcptr(&pt, NULL);
1567
1568
1569
1570
1571
1572
1573 epi->event.events = event->events;
1574 epi->event.data = event->data;
1575 if (epi->event.events & EPOLLWAKEUP) {
1576 if (!ep_has_wakeup_source(epi))
1577 ep_create_wakeup_source(epi);
1578 } else if (ep_has_wakeup_source(epi)) {
1579 ep_destroy_wakeup_source(epi);
1580 }
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600 smp_mb();
1601
1602
1603
1604
1605
1606
1607
1608 if (ep_item_poll(epi, &pt, 1)) {
1609 write_lock_irq(&ep->lock);
1610 if (!ep_is_linked(epi)) {
1611 list_add_tail(&epi->rdllink, &ep->rdllist);
1612 ep_pm_stay_awake(epi);
1613
1614
1615 if (waitqueue_active(&ep->wq))
1616 wake_up(&ep->wq);
1617 if (waitqueue_active(&ep->poll_wait))
1618 pwake++;
1619 }
1620 write_unlock_irq(&ep->lock);
1621 }
1622
1623
1624 if (pwake)
1625 ep_poll_safewake(ep, NULL);
1626
1627 return 0;
1628}
1629
1630static int ep_send_events(struct eventpoll *ep,
1631 struct epoll_event __user *events, int maxevents)
1632{
1633 struct epitem *epi, *tmp;
1634 LIST_HEAD(txlist);
1635 poll_table pt;
1636 int res = 0;
1637
1638
1639
1640
1641
1642
1643 if (fatal_signal_pending(current))
1644 return -EINTR;
1645
1646 init_poll_funcptr(&pt, NULL);
1647
1648 mutex_lock(&ep->mtx);
1649 ep_start_scan(ep, &txlist);
1650
1651
1652
1653
1654
1655 list_for_each_entry_safe(epi, tmp, &txlist, rdllink) {
1656 struct wakeup_source *ws;
1657 __poll_t revents;
1658
1659 if (res >= maxevents)
1660 break;
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671 ws = ep_wakeup_source(epi);
1672 if (ws) {
1673 if (ws->active)
1674 __pm_stay_awake(ep->ws);
1675 __pm_relax(ws);
1676 }
1677
1678 list_del_init(&epi->rdllink);
1679
1680
1681
1682
1683
1684
1685 revents = ep_item_poll(epi, &pt, 1);
1686 if (!revents)
1687 continue;
1688
1689 events = epoll_put_uevent(revents, epi->event.data, events);
1690 if (!events) {
1691 list_add(&epi->rdllink, &txlist);
1692 ep_pm_stay_awake(epi);
1693 if (!res)
1694 res = -EFAULT;
1695 break;
1696 }
1697 res++;
1698 if (epi->event.events & EPOLLONESHOT)
1699 epi->event.events &= EP_PRIVATE_BITS;
1700 else if (!(epi->event.events & EPOLLET)) {
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712 list_add_tail(&epi->rdllink, &ep->rdllist);
1713 ep_pm_stay_awake(epi);
1714 }
1715 }
1716 ep_done_scan(ep, &txlist);
1717 mutex_unlock(&ep->mtx);
1718
1719 return res;
1720}
1721
1722static struct timespec64 *ep_timeout_to_timespec(struct timespec64 *to, long ms)
1723{
1724 struct timespec64 now;
1725
1726 if (ms < 0)
1727 return NULL;
1728
1729 if (!ms) {
1730 to->tv_sec = 0;
1731 to->tv_nsec = 0;
1732 return to;
1733 }
1734
1735 to->tv_sec = ms / MSEC_PER_SEC;
1736 to->tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC);
1737
1738 ktime_get_ts64(&now);
1739 *to = timespec64_add_safe(now, *to);
1740 return to;
1741}
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
1761 int maxevents, struct timespec64 *timeout)
1762{
1763 int res, eavail, timed_out = 0;
1764 u64 slack = 0;
1765 wait_queue_entry_t wait;
1766 ktime_t expires, *to = NULL;
1767
1768 lockdep_assert_irqs_enabled();
1769
1770 if (timeout && (timeout->tv_sec | timeout->tv_nsec)) {
1771 slack = select_estimate_accuracy(timeout);
1772 to = &expires;
1773 *to = timespec64_to_ktime(*timeout);
1774 } else if (timeout) {
1775
1776
1777
1778
1779 timed_out = 1;
1780 }
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790 eavail = ep_events_available(ep);
1791
1792 while (1) {
1793 if (eavail) {
1794
1795
1796
1797
1798
1799 res = ep_send_events(ep, events, maxevents);
1800 if (res)
1801 return res;
1802 }
1803
1804 if (timed_out)
1805 return 0;
1806
1807 eavail = ep_busy_loop(ep, timed_out);
1808 if (eavail)
1809 continue;
1810
1811 if (signal_pending(current))
1812 return -EINTR;
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825 init_wait(&wait);
1826
1827 write_lock_irq(&ep->lock);
1828
1829
1830
1831
1832
1833 __set_current_state(TASK_INTERRUPTIBLE);
1834
1835
1836
1837
1838
1839
1840
1841
1842 eavail = ep_events_available(ep);
1843 if (!eavail)
1844 __add_wait_queue_exclusive(&ep->wq, &wait);
1845
1846 write_unlock_irq(&ep->lock);
1847
1848 if (!eavail)
1849 timed_out = !schedule_hrtimeout_range(to, slack,
1850 HRTIMER_MODE_ABS);
1851 __set_current_state(TASK_RUNNING);
1852
1853
1854
1855
1856
1857
1858 eavail = 1;
1859
1860 if (!list_empty_careful(&wait.entry)) {
1861 write_lock_irq(&ep->lock);
1862
1863
1864
1865
1866
1867
1868
1869 if (timed_out)
1870 eavail = list_empty(&wait.entry);
1871 __remove_wait_queue(&ep->wq, &wait);
1872 write_unlock_irq(&ep->lock);
1873 }
1874 }
1875}
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889static int ep_loop_check_proc(struct eventpoll *ep, int depth)
1890{
1891 int error = 0;
1892 struct rb_node *rbp;
1893 struct epitem *epi;
1894
1895 mutex_lock_nested(&ep->mtx, depth + 1);
1896 ep->gen = loop_check_gen;
1897 for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
1898 epi = rb_entry(rbp, struct epitem, rbn);
1899 if (unlikely(is_file_epoll(epi->ffd.file))) {
1900 struct eventpoll *ep_tovisit;
1901 ep_tovisit = epi->ffd.file->private_data;
1902 if (ep_tovisit->gen == loop_check_gen)
1903 continue;
1904 if (ep_tovisit == inserting_into || depth > EP_MAX_NESTS)
1905 error = -1;
1906 else
1907 error = ep_loop_check_proc(ep_tovisit, depth + 1);
1908 if (error != 0)
1909 break;
1910 } else {
1911
1912
1913
1914
1915
1916
1917
1918
1919 list_file(epi->ffd.file);
1920 }
1921 }
1922 mutex_unlock(&ep->mtx);
1923
1924 return error;
1925}
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938static int ep_loop_check(struct eventpoll *ep, struct eventpoll *to)
1939{
1940 inserting_into = ep;
1941 return ep_loop_check_proc(to, 0);
1942}
1943
1944static void clear_tfile_check_list(void)
1945{
1946 rcu_read_lock();
1947 while (tfile_check_list != EP_UNACTIVE_PTR) {
1948 struct epitems_head *head = tfile_check_list;
1949 tfile_check_list = head->next;
1950 unlist_file(head);
1951 }
1952 rcu_read_unlock();
1953}
1954
1955
1956
1957
1958static int do_epoll_create(int flags)
1959{
1960 int error, fd;
1961 struct eventpoll *ep = NULL;
1962 struct file *file;
1963
1964
1965 BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
1966
1967 if (flags & ~EPOLL_CLOEXEC)
1968 return -EINVAL;
1969
1970
1971
1972 error = ep_alloc(&ep);
1973 if (error < 0)
1974 return error;
1975
1976
1977
1978
1979 fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
1980 if (fd < 0) {
1981 error = fd;
1982 goto out_free_ep;
1983 }
1984 file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
1985 O_RDWR | (flags & O_CLOEXEC));
1986 if (IS_ERR(file)) {
1987 error = PTR_ERR(file);
1988 goto out_free_fd;
1989 }
1990 ep->file = file;
1991 fd_install(fd, file);
1992 return fd;
1993
1994out_free_fd:
1995 put_unused_fd(fd);
1996out_free_ep:
1997 ep_free(ep);
1998 return error;
1999}
2000
2001SYSCALL_DEFINE1(epoll_create1, int, flags)
2002{
2003 return do_epoll_create(flags);
2004}
2005
2006SYSCALL_DEFINE1(epoll_create, int, size)
2007{
2008 if (size <= 0)
2009 return -EINVAL;
2010
2011 return do_epoll_create(0);
2012}
2013
2014static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
2015 bool nonblock)
2016{
2017 if (!nonblock) {
2018 mutex_lock_nested(mutex, depth);
2019 return 0;
2020 }
2021 if (mutex_trylock(mutex))
2022 return 0;
2023 return -EAGAIN;
2024}
2025
2026int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
2027 bool nonblock)
2028{
2029 int error;
2030 int full_check = 0;
2031 struct fd f, tf;
2032 struct eventpoll *ep;
2033 struct epitem *epi;
2034 struct eventpoll *tep = NULL;
2035
2036 error = -EBADF;
2037 f = fdget(epfd);
2038 if (!f.file)
2039 goto error_return;
2040
2041
2042 tf = fdget(fd);
2043 if (!tf.file)
2044 goto error_fput;
2045
2046
2047 error = -EPERM;
2048 if (!file_can_poll(tf.file))
2049 goto error_tgt_fput;
2050
2051
2052 if (ep_op_has_event(op))
2053 ep_take_care_of_epollwakeup(epds);
2054
2055
2056
2057
2058
2059
2060 error = -EINVAL;
2061 if (f.file == tf.file || !is_file_epoll(f.file))
2062 goto error_tgt_fput;
2063
2064
2065
2066
2067
2068
2069 if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
2070 if (op == EPOLL_CTL_MOD)
2071 goto error_tgt_fput;
2072 if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
2073 (epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
2074 goto error_tgt_fput;
2075 }
2076
2077
2078
2079
2080
2081 ep = f.file->private_data;
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098 error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
2099 if (error)
2100 goto error_tgt_fput;
2101 if (op == EPOLL_CTL_ADD) {
2102 if (READ_ONCE(f.file->f_ep) || ep->gen == loop_check_gen ||
2103 is_file_epoll(tf.file)) {
2104 mutex_unlock(&ep->mtx);
2105 error = epoll_mutex_lock(&epmutex, 0, nonblock);
2106 if (error)
2107 goto error_tgt_fput;
2108 loop_check_gen++;
2109 full_check = 1;
2110 if (is_file_epoll(tf.file)) {
2111 tep = tf.file->private_data;
2112 error = -ELOOP;
2113 if (ep_loop_check(ep, tep) != 0)
2114 goto error_tgt_fput;
2115 }
2116 error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
2117 if (error)
2118 goto error_tgt_fput;
2119 }
2120 }
2121
2122
2123
2124
2125
2126
2127 epi = ep_find(ep, tf.file, fd);
2128
2129 error = -EINVAL;
2130 switch (op) {
2131 case EPOLL_CTL_ADD:
2132 if (!epi) {
2133 epds->events |= EPOLLERR | EPOLLHUP;
2134 error = ep_insert(ep, epds, tf.file, fd, full_check);
2135 } else
2136 error = -EEXIST;
2137 break;
2138 case EPOLL_CTL_DEL:
2139 if (epi)
2140 error = ep_remove(ep, epi);
2141 else
2142 error = -ENOENT;
2143 break;
2144 case EPOLL_CTL_MOD:
2145 if (epi) {
2146 if (!(epi->event.events & EPOLLEXCLUSIVE)) {
2147 epds->events |= EPOLLERR | EPOLLHUP;
2148 error = ep_modify(ep, epi, epds);
2149 }
2150 } else
2151 error = -ENOENT;
2152 break;
2153 }
2154 mutex_unlock(&ep->mtx);
2155
2156error_tgt_fput:
2157 if (full_check) {
2158 clear_tfile_check_list();
2159 loop_check_gen++;
2160 mutex_unlock(&epmutex);
2161 }
2162
2163 fdput(tf);
2164error_fput:
2165 fdput(f);
2166error_return:
2167
2168 return error;
2169}
2170
2171
2172
2173
2174
2175
2176SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
2177 struct epoll_event __user *, event)
2178{
2179 struct epoll_event epds;
2180
2181 if (ep_op_has_event(op) &&
2182 copy_from_user(&epds, event, sizeof(struct epoll_event)))
2183 return -EFAULT;
2184
2185 return do_epoll_ctl(epfd, op, fd, &epds, false);
2186}
2187
2188
2189
2190
2191
2192static int do_epoll_wait(int epfd, struct epoll_event __user *events,
2193 int maxevents, struct timespec64 *to)
2194{
2195 int error;
2196 struct fd f;
2197 struct eventpoll *ep;
2198
2199
2200 if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
2201 return -EINVAL;
2202
2203
2204 if (!access_ok(events, maxevents * sizeof(struct epoll_event)))
2205 return -EFAULT;
2206
2207
2208 f = fdget(epfd);
2209 if (!f.file)
2210 return -EBADF;
2211
2212
2213
2214
2215
2216 error = -EINVAL;
2217 if (!is_file_epoll(f.file))
2218 goto error_fput;
2219
2220
2221
2222
2223
2224 ep = f.file->private_data;
2225
2226
2227 error = ep_poll(ep, events, maxevents, to);
2228
2229error_fput:
2230 fdput(f);
2231 return error;
2232}
2233
2234SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
2235 int, maxevents, int, timeout)
2236{
2237 struct timespec64 to;
2238
2239 return do_epoll_wait(epfd, events, maxevents,
2240 ep_timeout_to_timespec(&to, timeout));
2241}
2242
2243
2244
2245
2246
2247static int do_epoll_pwait(int epfd, struct epoll_event __user *events,
2248 int maxevents, struct timespec64 *to,
2249 const sigset_t __user *sigmask, size_t sigsetsize)
2250{
2251 int error;
2252
2253
2254
2255
2256
2257 error = set_user_sigmask(sigmask, sigsetsize);
2258 if (error)
2259 return error;
2260
2261 error = do_epoll_wait(epfd, events, maxevents, to);
2262
2263 restore_saved_sigmask_unless(error == -EINTR);
2264
2265 return error;
2266}
2267
2268SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
2269 int, maxevents, int, timeout, const sigset_t __user *, sigmask,
2270 size_t, sigsetsize)
2271{
2272 struct timespec64 to;
2273
2274 return do_epoll_pwait(epfd, events, maxevents,
2275 ep_timeout_to_timespec(&to, timeout),
2276 sigmask, sigsetsize);
2277}
2278
2279SYSCALL_DEFINE6(epoll_pwait2, int, epfd, struct epoll_event __user *, events,
2280 int, maxevents, const struct __kernel_timespec __user *, timeout,
2281 const sigset_t __user *, sigmask, size_t, sigsetsize)
2282{
2283 struct timespec64 ts, *to = NULL;
2284
2285 if (timeout) {
2286 if (get_timespec64(&ts, timeout))
2287 return -EFAULT;
2288 to = &ts;
2289 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
2290 return -EINVAL;
2291 }
2292
2293 return do_epoll_pwait(epfd, events, maxevents, to,
2294 sigmask, sigsetsize);
2295}
2296
2297#ifdef CONFIG_COMPAT
2298static int do_compat_epoll_pwait(int epfd, struct epoll_event __user *events,
2299 int maxevents, struct timespec64 *timeout,
2300 const compat_sigset_t __user *sigmask,
2301 compat_size_t sigsetsize)
2302{
2303 long err;
2304
2305
2306
2307
2308
2309 err = set_compat_user_sigmask(sigmask, sigsetsize);
2310 if (err)
2311 return err;
2312
2313 err = do_epoll_wait(epfd, events, maxevents, timeout);
2314
2315 restore_saved_sigmask_unless(err == -EINTR);
2316
2317 return err;
2318}
2319
2320COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
2321 struct epoll_event __user *, events,
2322 int, maxevents, int, timeout,
2323 const compat_sigset_t __user *, sigmask,
2324 compat_size_t, sigsetsize)
2325{
2326 struct timespec64 to;
2327
2328 return do_compat_epoll_pwait(epfd, events, maxevents,
2329 ep_timeout_to_timespec(&to, timeout),
2330 sigmask, sigsetsize);
2331}
2332
2333COMPAT_SYSCALL_DEFINE6(epoll_pwait2, int, epfd,
2334 struct epoll_event __user *, events,
2335 int, maxevents,
2336 const struct __kernel_timespec __user *, timeout,
2337 const compat_sigset_t __user *, sigmask,
2338 compat_size_t, sigsetsize)
2339{
2340 struct timespec64 ts, *to = NULL;
2341
2342 if (timeout) {
2343 if (get_timespec64(&ts, timeout))
2344 return -EFAULT;
2345 to = &ts;
2346 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
2347 return -EINVAL;
2348 }
2349
2350 return do_compat_epoll_pwait(epfd, events, maxevents, to,
2351 sigmask, sigsetsize);
2352}
2353
2354#endif
2355
2356static int __init eventpoll_init(void)
2357{
2358 struct sysinfo si;
2359
2360 si_meminfo(&si);
2361
2362
2363
2364 max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
2365 EP_ITEM_COST;
2366 BUG_ON(max_user_watches < 0);
2367
2368
2369
2370
2371
2372 BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128);
2373
2374
2375 epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
2376 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
2377
2378
2379 pwq_cache = kmem_cache_create("eventpoll_pwq",
2380 sizeof(struct eppoll_entry), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL);
2381
2382 ephead_cache = kmem_cache_create("ep_head",
2383 sizeof(struct epitems_head), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL);
2384
2385 return 0;
2386}
2387fs_initcall(eventpoll_init);
2388