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14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/file.h>
19#include <linux/signal.h>
20#include <linux/errno.h>
21#include <linux/mm.h>
22#include <linux/slab.h>
23#include <linux/poll.h>
24#include <linux/string.h>
25#include <linux/list.h>
26#include <linux/hash.h>
27#include <linux/spinlock.h>
28#include <linux/syscalls.h>
29#include <linux/rbtree.h>
30#include <linux/wait.h>
31#include <linux/eventpoll.h>
32#include <linux/mount.h>
33#include <linux/bitops.h>
34#include <linux/mutex.h>
35#include <linux/anon_inodes.h>
36#include <linux/device.h>
37#include <asm/uaccess.h>
38#include <asm/io.h>
39#include <asm/mman.h>
40#include <linux/atomic.h>
41#include <linux/proc_fs.h>
42#include <linux/seq_file.h>
43#include <linux/compat.h>
44
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93
94#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET)
95
96
97#define EP_MAX_NESTS 4
98
99#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
100
101#define EP_UNACTIVE_PTR ((void *) -1L)
102
103#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
104
105struct epoll_filefd {
106 struct file *file;
107 int fd;
108} __packed;
109
110
111
112
113
114struct nested_call_node {
115 struct list_head llink;
116 void *cookie;
117 void *ctx;
118};
119
120
121
122
123
124struct nested_calls {
125 struct list_head tasks_call_list;
126 spinlock_t lock;
127};
128
129
130
131
132
133
134
135struct epitem {
136
137 struct rb_node rbn;
138
139
140 struct list_head rdllink;
141
142
143
144
145
146 struct epitem *next;
147
148
149 struct epoll_filefd ffd;
150
151
152 int nwait;
153
154
155 struct list_head pwqlist;
156
157
158 struct eventpoll *ep;
159
160
161 struct list_head fllink;
162
163
164 struct wakeup_source __rcu *ws;
165
166
167 struct epoll_event event;
168};
169
170
171
172
173
174
175struct eventpoll {
176
177 spinlock_t lock;
178
179
180
181
182
183
184
185 struct mutex mtx;
186
187
188 wait_queue_head_t wq;
189
190
191 wait_queue_head_t poll_wait;
192
193
194 struct list_head rdllist;
195
196
197 struct rb_root rbr;
198
199
200
201
202
203
204 struct epitem *ovflist;
205
206
207 struct wakeup_source *ws;
208
209
210 struct user_struct *user;
211
212 struct file *file;
213
214
215 int visited;
216 struct list_head visited_list_link;
217};
218
219
220struct eppoll_entry {
221
222 struct list_head llink;
223
224
225 struct epitem *base;
226
227
228
229
230
231 wait_queue_t wait;
232
233
234 wait_queue_head_t *whead;
235};
236
237
238struct ep_pqueue {
239 poll_table pt;
240 struct epitem *epi;
241};
242
243
244struct ep_send_events_data {
245 int maxevents;
246 struct epoll_event __user *events;
247};
248
249
250
251
252
253static long max_user_watches __read_mostly;
254
255
256
257
258static DEFINE_MUTEX(epmutex);
259
260
261static struct nested_calls poll_loop_ncalls;
262
263
264static struct nested_calls poll_safewake_ncalls;
265
266
267static struct nested_calls poll_readywalk_ncalls;
268
269
270static struct kmem_cache *epi_cache __read_mostly;
271
272
273static struct kmem_cache *pwq_cache __read_mostly;
274
275
276static LIST_HEAD(visited_list);
277
278
279
280
281
282static LIST_HEAD(tfile_check_list);
283
284#ifdef CONFIG_SYSCTL
285
286#include <linux/sysctl.h>
287
288static long zero;
289static long long_max = LONG_MAX;
290
291ctl_table epoll_table[] = {
292 {
293 .procname = "max_user_watches",
294 .data = &max_user_watches,
295 .maxlen = sizeof(max_user_watches),
296 .mode = 0644,
297 .proc_handler = proc_doulongvec_minmax,
298 .extra1 = &zero,
299 .extra2 = &long_max,
300 },
301 { }
302};
303#endif
304
305static const struct file_operations eventpoll_fops;
306
307static inline int is_file_epoll(struct file *f)
308{
309 return f->f_op == &eventpoll_fops;
310}
311
312
313static inline void ep_set_ffd(struct epoll_filefd *ffd,
314 struct file *file, int fd)
315{
316 ffd->file = file;
317 ffd->fd = fd;
318}
319
320
321static inline int ep_cmp_ffd(struct epoll_filefd *p1,
322 struct epoll_filefd *p2)
323{
324 return (p1->file > p2->file ? +1:
325 (p1->file < p2->file ? -1 : p1->fd - p2->fd));
326}
327
328
329static inline int ep_is_linked(struct list_head *p)
330{
331 return !list_empty(p);
332}
333
334static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_t *p)
335{
336 return container_of(p, struct eppoll_entry, wait);
337}
338
339
340static inline struct epitem *ep_item_from_wait(wait_queue_t *p)
341{
342 return container_of(p, struct eppoll_entry, wait)->base;
343}
344
345
346static inline struct epitem *ep_item_from_epqueue(poll_table *p)
347{
348 return container_of(p, struct ep_pqueue, pt)->epi;
349}
350
351
352static inline int ep_op_has_event(int op)
353{
354 return op != EPOLL_CTL_DEL;
355}
356
357
358static void ep_nested_calls_init(struct nested_calls *ncalls)
359{
360 INIT_LIST_HEAD(&ncalls->tasks_call_list);
361 spin_lock_init(&ncalls->lock);
362}
363
364
365
366
367
368
369
370
371
372static inline int ep_events_available(struct eventpoll *ep)
373{
374 return !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR;
375}
376
377
378
379
380
381
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389
390
391
392
393static int ep_call_nested(struct nested_calls *ncalls, int max_nests,
394 int (*nproc)(void *, void *, int), void *priv,
395 void *cookie, void *ctx)
396{
397 int error, call_nests = 0;
398 unsigned long flags;
399 struct list_head *lsthead = &ncalls->tasks_call_list;
400 struct nested_call_node *tncur;
401 struct nested_call_node tnode;
402
403 spin_lock_irqsave(&ncalls->lock, flags);
404
405
406
407
408
409
410 list_for_each_entry(tncur, lsthead, llink) {
411 if (tncur->ctx == ctx &&
412 (tncur->cookie == cookie || ++call_nests > max_nests)) {
413
414
415
416
417 error = -1;
418 goto out_unlock;
419 }
420 }
421
422
423 tnode.ctx = ctx;
424 tnode.cookie = cookie;
425 list_add(&tnode.llink, lsthead);
426
427 spin_unlock_irqrestore(&ncalls->lock, flags);
428
429
430 error = (*nproc)(priv, cookie, call_nests);
431
432
433 spin_lock_irqsave(&ncalls->lock, flags);
434 list_del(&tnode.llink);
435out_unlock:
436 spin_unlock_irqrestore(&ncalls->lock, flags);
437
438 return error;
439}
440
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465
466#ifdef CONFIG_DEBUG_LOCK_ALLOC
467static inline void ep_wake_up_nested(wait_queue_head_t *wqueue,
468 unsigned long events, int subclass)
469{
470 unsigned long flags;
471
472 spin_lock_irqsave_nested(&wqueue->lock, flags, subclass);
473 wake_up_locked_poll(wqueue, events);
474 spin_unlock_irqrestore(&wqueue->lock, flags);
475}
476#else
477static inline void ep_wake_up_nested(wait_queue_head_t *wqueue,
478 unsigned long events, int subclass)
479{
480 wake_up_poll(wqueue, events);
481}
482#endif
483
484static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests)
485{
486 ep_wake_up_nested((wait_queue_head_t *) cookie, POLLIN,
487 1 + call_nests);
488 return 0;
489}
490
491
492
493
494
495
496
497
498
499
500
501static void ep_poll_safewake(wait_queue_head_t *wq)
502{
503 int this_cpu = get_cpu();
504
505 ep_call_nested(&poll_safewake_ncalls, EP_MAX_NESTS,
506 ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu);
507
508 put_cpu();
509}
510
511static void ep_remove_wait_queue(struct eppoll_entry *pwq)
512{
513 wait_queue_head_t *whead;
514
515 rcu_read_lock();
516
517 whead = rcu_dereference(pwq->whead);
518 if (whead)
519 remove_wait_queue(whead, &pwq->wait);
520 rcu_read_unlock();
521}
522
523
524
525
526
527
528static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
529{
530 struct list_head *lsthead = &epi->pwqlist;
531 struct eppoll_entry *pwq;
532
533 while (!list_empty(lsthead)) {
534 pwq = list_first_entry(lsthead, struct eppoll_entry, llink);
535
536 list_del(&pwq->llink);
537 ep_remove_wait_queue(pwq);
538 kmem_cache_free(pwq_cache, pwq);
539 }
540}
541
542
543static inline struct wakeup_source *ep_wakeup_source(struct epitem *epi)
544{
545 return rcu_dereference_check(epi->ws, lockdep_is_held(&epi->ep->mtx));
546}
547
548
549static inline void ep_pm_stay_awake(struct epitem *epi)
550{
551 struct wakeup_source *ws = ep_wakeup_source(epi);
552
553 if (ws)
554 __pm_stay_awake(ws);
555}
556
557static inline bool ep_has_wakeup_source(struct epitem *epi)
558{
559 return rcu_access_pointer(epi->ws) ? true : false;
560}
561
562
563static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
564{
565 struct wakeup_source *ws;
566
567 rcu_read_lock();
568 ws = rcu_dereference(epi->ws);
569 if (ws)
570 __pm_stay_awake(ws);
571 rcu_read_unlock();
572}
573
574
575
576
577
578
579
580
581
582
583
584
585
586static int ep_scan_ready_list(struct eventpoll *ep,
587 int (*sproc)(struct eventpoll *,
588 struct list_head *, void *),
589 void *priv,
590 int depth)
591{
592 int error, pwake = 0;
593 unsigned long flags;
594 struct epitem *epi, *nepi;
595 LIST_HEAD(txlist);
596
597
598
599
600
601 mutex_lock_nested(&ep->mtx, depth);
602
603
604
605
606
607
608
609
610
611 spin_lock_irqsave(&ep->lock, flags);
612 list_splice_init(&ep->rdllist, &txlist);
613 ep->ovflist = NULL;
614 spin_unlock_irqrestore(&ep->lock, flags);
615
616
617
618
619 error = (*sproc)(ep, &txlist, priv);
620
621 spin_lock_irqsave(&ep->lock, flags);
622
623
624
625
626
627 for (nepi = ep->ovflist; (epi = nepi) != NULL;
628 nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
629
630
631
632
633
634
635 if (!ep_is_linked(&epi->rdllink)) {
636 list_add_tail(&epi->rdllink, &ep->rdllist);
637 ep_pm_stay_awake(epi);
638 }
639 }
640
641
642
643
644
645 ep->ovflist = EP_UNACTIVE_PTR;
646
647
648
649
650 list_splice(&txlist, &ep->rdllist);
651 __pm_relax(ep->ws);
652
653 if (!list_empty(&ep->rdllist)) {
654
655
656
657
658 if (waitqueue_active(&ep->wq))
659 wake_up_locked(&ep->wq);
660 if (waitqueue_active(&ep->poll_wait))
661 pwake++;
662 }
663 spin_unlock_irqrestore(&ep->lock, flags);
664
665 mutex_unlock(&ep->mtx);
666
667
668 if (pwake)
669 ep_poll_safewake(&ep->poll_wait);
670
671 return error;
672}
673
674
675
676
677
678static int ep_remove(struct eventpoll *ep, struct epitem *epi)
679{
680 unsigned long flags;
681 struct file *file = epi->ffd.file;
682
683
684
685
686
687
688
689
690
691 ep_unregister_pollwait(ep, epi);
692
693
694 spin_lock(&file->f_lock);
695 if (ep_is_linked(&epi->fllink))
696 list_del_init(&epi->fllink);
697 spin_unlock(&file->f_lock);
698
699 rb_erase(&epi->rbn, &ep->rbr);
700
701 spin_lock_irqsave(&ep->lock, flags);
702 if (ep_is_linked(&epi->rdllink))
703 list_del_init(&epi->rdllink);
704 spin_unlock_irqrestore(&ep->lock, flags);
705
706 wakeup_source_unregister(ep_wakeup_source(epi));
707
708
709 kmem_cache_free(epi_cache, epi);
710
711 atomic_long_dec(&ep->user->epoll_watches);
712
713 return 0;
714}
715
716static void ep_free(struct eventpoll *ep)
717{
718 struct rb_node *rbp;
719 struct epitem *epi;
720
721
722 if (waitqueue_active(&ep->poll_wait))
723 ep_poll_safewake(&ep->poll_wait);
724
725
726
727
728
729
730
731
732
733 mutex_lock(&epmutex);
734
735
736
737
738 for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
739 epi = rb_entry(rbp, struct epitem, rbn);
740
741 ep_unregister_pollwait(ep, epi);
742 }
743
744
745
746
747
748
749
750
751
752 mutex_lock(&ep->mtx);
753 while ((rbp = rb_first(&ep->rbr)) != NULL) {
754 epi = rb_entry(rbp, struct epitem, rbn);
755 ep_remove(ep, epi);
756 }
757 mutex_unlock(&ep->mtx);
758
759 mutex_unlock(&epmutex);
760 mutex_destroy(&ep->mtx);
761 free_uid(ep->user);
762 wakeup_source_unregister(ep->ws);
763 kfree(ep);
764}
765
766static int ep_eventpoll_release(struct inode *inode, struct file *file)
767{
768 struct eventpoll *ep = file->private_data;
769
770 if (ep)
771 ep_free(ep);
772
773 return 0;
774}
775
776static inline unsigned int ep_item_poll(struct epitem *epi, poll_table *pt)
777{
778 pt->_key = epi->event.events;
779
780 return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & epi->event.events;
781}
782
783static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
784 void *priv)
785{
786 struct epitem *epi, *tmp;
787 poll_table pt;
788
789 init_poll_funcptr(&pt, NULL);
790
791 list_for_each_entry_safe(epi, tmp, head, rdllink) {
792 if (ep_item_poll(epi, &pt))
793 return POLLIN | POLLRDNORM;
794 else {
795
796
797
798
799
800 __pm_relax(ep_wakeup_source(epi));
801 list_del_init(&epi->rdllink);
802 }
803 }
804
805 return 0;
806}
807
808static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests)
809{
810 return ep_scan_ready_list(priv, ep_read_events_proc, NULL, call_nests + 1);
811}
812
813static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
814{
815 int pollflags;
816 struct eventpoll *ep = file->private_data;
817
818
819 poll_wait(file, &ep->poll_wait, wait);
820
821
822
823
824
825
826
827 pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS,
828 ep_poll_readyevents_proc, ep, ep, current);
829
830 return pollflags != -1 ? pollflags : 0;
831}
832
833#ifdef CONFIG_PROC_FS
834static int ep_show_fdinfo(struct seq_file *m, struct file *f)
835{
836 struct eventpoll *ep = f->private_data;
837 struct rb_node *rbp;
838 int ret = 0;
839
840 mutex_lock(&ep->mtx);
841 for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
842 struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
843
844 ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
845 epi->ffd.fd, epi->event.events,
846 (long long)epi->event.data);
847 if (ret)
848 break;
849 }
850 mutex_unlock(&ep->mtx);
851
852 return ret;
853}
854#endif
855
856
857static const struct file_operations eventpoll_fops = {
858#ifdef CONFIG_PROC_FS
859 .show_fdinfo = ep_show_fdinfo,
860#endif
861 .release = ep_eventpoll_release,
862 .poll = ep_eventpoll_poll,
863 .llseek = noop_llseek,
864};
865
866
867
868
869
870
871void eventpoll_release_file(struct file *file)
872{
873 struct list_head *lsthead = &file->f_ep_links;
874 struct eventpoll *ep;
875 struct epitem *epi;
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890 mutex_lock(&epmutex);
891
892 while (!list_empty(lsthead)) {
893 epi = list_first_entry(lsthead, struct epitem, fllink);
894
895 ep = epi->ep;
896 list_del_init(&epi->fllink);
897 mutex_lock_nested(&ep->mtx, 0);
898 ep_remove(ep, epi);
899 mutex_unlock(&ep->mtx);
900 }
901
902 mutex_unlock(&epmutex);
903}
904
905static int ep_alloc(struct eventpoll **pep)
906{
907 int error;
908 struct user_struct *user;
909 struct eventpoll *ep;
910
911 user = get_current_user();
912 error = -ENOMEM;
913 ep = kzalloc(sizeof(*ep), GFP_KERNEL);
914 if (unlikely(!ep))
915 goto free_uid;
916
917 spin_lock_init(&ep->lock);
918 mutex_init(&ep->mtx);
919 init_waitqueue_head(&ep->wq);
920 init_waitqueue_head(&ep->poll_wait);
921 INIT_LIST_HEAD(&ep->rdllist);
922 ep->rbr = RB_ROOT;
923 ep->ovflist = EP_UNACTIVE_PTR;
924 ep->user = user;
925
926 *pep = ep;
927
928 return 0;
929
930free_uid:
931 free_uid(user);
932 return error;
933}
934
935
936
937
938
939
940static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
941{
942 int kcmp;
943 struct rb_node *rbp;
944 struct epitem *epi, *epir = NULL;
945 struct epoll_filefd ffd;
946
947 ep_set_ffd(&ffd, file, fd);
948 for (rbp = ep->rbr.rb_node; rbp; ) {
949 epi = rb_entry(rbp, struct epitem, rbn);
950 kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
951 if (kcmp > 0)
952 rbp = rbp->rb_right;
953 else if (kcmp < 0)
954 rbp = rbp->rb_left;
955 else {
956 epir = epi;
957 break;
958 }
959 }
960
961 return epir;
962}
963
964
965
966
967
968
969static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
970{
971 int pwake = 0;
972 unsigned long flags;
973 struct epitem *epi = ep_item_from_wait(wait);
974 struct eventpoll *ep = epi->ep;
975
976 if ((unsigned long)key & POLLFREE) {
977 ep_pwq_from_wait(wait)->whead = NULL;
978
979
980
981
982
983
984 list_del_init(&wait->task_list);
985 }
986
987 spin_lock_irqsave(&ep->lock, flags);
988
989
990
991
992
993
994
995 if (!(epi->event.events & ~EP_PRIVATE_BITS))
996 goto out_unlock;
997
998
999
1000
1001
1002
1003
1004 if (key && !((unsigned long) key & epi->event.events))
1005 goto out_unlock;
1006
1007
1008
1009
1010
1011
1012
1013 if (unlikely(ep->ovflist != EP_UNACTIVE_PTR)) {
1014 if (epi->next == EP_UNACTIVE_PTR) {
1015 epi->next = ep->ovflist;
1016 ep->ovflist = epi;
1017 if (epi->ws) {
1018
1019
1020
1021
1022 __pm_stay_awake(ep->ws);
1023 }
1024
1025 }
1026 goto out_unlock;
1027 }
1028
1029
1030 if (!ep_is_linked(&epi->rdllink)) {
1031 list_add_tail(&epi->rdllink, &ep->rdllist);
1032 ep_pm_stay_awake_rcu(epi);
1033 }
1034
1035
1036
1037
1038
1039 if (waitqueue_active(&ep->wq))
1040 wake_up_locked(&ep->wq);
1041 if (waitqueue_active(&ep->poll_wait))
1042 pwake++;
1043
1044out_unlock:
1045 spin_unlock_irqrestore(&ep->lock, flags);
1046
1047
1048 if (pwake)
1049 ep_poll_safewake(&ep->poll_wait);
1050
1051 return 1;
1052}
1053
1054
1055
1056
1057
1058static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
1059 poll_table *pt)
1060{
1061 struct epitem *epi = ep_item_from_epqueue(pt);
1062 struct eppoll_entry *pwq;
1063
1064 if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
1065 init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
1066 pwq->whead = whead;
1067 pwq->base = epi;
1068 add_wait_queue(whead, &pwq->wait);
1069 list_add_tail(&pwq->llink, &epi->pwqlist);
1070 epi->nwait++;
1071 } else {
1072
1073 epi->nwait = -1;
1074 }
1075}
1076
1077static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
1078{
1079 int kcmp;
1080 struct rb_node **p = &ep->rbr.rb_node, *parent = NULL;
1081 struct epitem *epic;
1082
1083 while (*p) {
1084 parent = *p;
1085 epic = rb_entry(parent, struct epitem, rbn);
1086 kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
1087 if (kcmp > 0)
1088 p = &parent->rb_right;
1089 else
1090 p = &parent->rb_left;
1091 }
1092 rb_link_node(&epi->rbn, parent, p);
1093 rb_insert_color(&epi->rbn, &ep->rbr);
1094}
1095
1096
1097
1098#define PATH_ARR_SIZE 5
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
1111static int path_count[PATH_ARR_SIZE];
1112
1113static int path_count_inc(int nests)
1114{
1115
1116 if (nests == 0)
1117 return 0;
1118
1119 if (++path_count[nests] > path_limits[nests])
1120 return -1;
1121 return 0;
1122}
1123
1124static void path_count_init(void)
1125{
1126 int i;
1127
1128 for (i = 0; i < PATH_ARR_SIZE; i++)
1129 path_count[i] = 0;
1130}
1131
1132static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)
1133{
1134 int error = 0;
1135 struct file *file = priv;
1136 struct file *child_file;
1137 struct epitem *epi;
1138
1139 list_for_each_entry(epi, &file->f_ep_links, fllink) {
1140 child_file = epi->ep->file;
1141 if (is_file_epoll(child_file)) {
1142 if (list_empty(&child_file->f_ep_links)) {
1143 if (path_count_inc(call_nests)) {
1144 error = -1;
1145 break;
1146 }
1147 } else {
1148 error = ep_call_nested(&poll_loop_ncalls,
1149 EP_MAX_NESTS,
1150 reverse_path_check_proc,
1151 child_file, child_file,
1152 current);
1153 }
1154 if (error != 0)
1155 break;
1156 } else {
1157 printk(KERN_ERR "reverse_path_check_proc: "
1158 "file is not an ep!\n");
1159 }
1160 }
1161 return error;
1162}
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174static int reverse_path_check(void)
1175{
1176 int error = 0;
1177 struct file *current_file;
1178
1179
1180 list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {
1181 path_count_init();
1182 error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1183 reverse_path_check_proc, current_file,
1184 current_file, current);
1185 if (error)
1186 break;
1187 }
1188 return error;
1189}
1190
1191static int ep_create_wakeup_source(struct epitem *epi)
1192{
1193 const char *name;
1194 struct wakeup_source *ws;
1195
1196 if (!epi->ep->ws) {
1197 epi->ep->ws = wakeup_source_register("eventpoll");
1198 if (!epi->ep->ws)
1199 return -ENOMEM;
1200 }
1201
1202 name = epi->ffd.file->f_path.dentry->d_name.name;
1203 ws = wakeup_source_register(name);
1204
1205 if (!ws)
1206 return -ENOMEM;
1207 rcu_assign_pointer(epi->ws, ws);
1208
1209 return 0;
1210}
1211
1212
1213static noinline void ep_destroy_wakeup_source(struct epitem *epi)
1214{
1215 struct wakeup_source *ws = ep_wakeup_source(epi);
1216
1217 RCU_INIT_POINTER(epi->ws, NULL);
1218
1219
1220
1221
1222
1223
1224 synchronize_rcu();
1225 wakeup_source_unregister(ws);
1226}
1227
1228
1229
1230
1231static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
1232 struct file *tfile, int fd)
1233{
1234 int error, revents, pwake = 0;
1235 unsigned long flags;
1236 long user_watches;
1237 struct epitem *epi;
1238 struct ep_pqueue epq;
1239
1240 user_watches = atomic_long_read(&ep->user->epoll_watches);
1241 if (unlikely(user_watches >= max_user_watches))
1242 return -ENOSPC;
1243 if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
1244 return -ENOMEM;
1245
1246
1247 INIT_LIST_HEAD(&epi->rdllink);
1248 INIT_LIST_HEAD(&epi->fllink);
1249 INIT_LIST_HEAD(&epi->pwqlist);
1250 epi->ep = ep;
1251 ep_set_ffd(&epi->ffd, tfile, fd);
1252 epi->event = *event;
1253 epi->nwait = 0;
1254 epi->next = EP_UNACTIVE_PTR;
1255 if (epi->event.events & EPOLLWAKEUP) {
1256 error = ep_create_wakeup_source(epi);
1257 if (error)
1258 goto error_create_wakeup_source;
1259 } else {
1260 RCU_INIT_POINTER(epi->ws, NULL);
1261 }
1262
1263
1264 epq.epi = epi;
1265 init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
1266
1267
1268
1269
1270
1271
1272
1273
1274 revents = ep_item_poll(epi, &epq.pt);
1275
1276
1277
1278
1279
1280
1281 error = -ENOMEM;
1282 if (epi->nwait < 0)
1283 goto error_unregister;
1284
1285
1286 spin_lock(&tfile->f_lock);
1287 list_add_tail(&epi->fllink, &tfile->f_ep_links);
1288 spin_unlock(&tfile->f_lock);
1289
1290
1291
1292
1293
1294 ep_rbtree_insert(ep, epi);
1295
1296
1297 error = -EINVAL;
1298 if (reverse_path_check())
1299 goto error_remove_epi;
1300
1301
1302 spin_lock_irqsave(&ep->lock, flags);
1303
1304
1305 if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) {
1306 list_add_tail(&epi->rdllink, &ep->rdllist);
1307 ep_pm_stay_awake(epi);
1308
1309
1310 if (waitqueue_active(&ep->wq))
1311 wake_up_locked(&ep->wq);
1312 if (waitqueue_active(&ep->poll_wait))
1313 pwake++;
1314 }
1315
1316 spin_unlock_irqrestore(&ep->lock, flags);
1317
1318 atomic_long_inc(&ep->user->epoll_watches);
1319
1320
1321 if (pwake)
1322 ep_poll_safewake(&ep->poll_wait);
1323
1324 return 0;
1325
1326error_remove_epi:
1327 spin_lock(&tfile->f_lock);
1328 if (ep_is_linked(&epi->fllink))
1329 list_del_init(&epi->fllink);
1330 spin_unlock(&tfile->f_lock);
1331
1332 rb_erase(&epi->rbn, &ep->rbr);
1333
1334error_unregister:
1335 ep_unregister_pollwait(ep, epi);
1336
1337
1338
1339
1340
1341
1342
1343 spin_lock_irqsave(&ep->lock, flags);
1344 if (ep_is_linked(&epi->rdllink))
1345 list_del_init(&epi->rdllink);
1346 spin_unlock_irqrestore(&ep->lock, flags);
1347
1348 wakeup_source_unregister(ep_wakeup_source(epi));
1349
1350error_create_wakeup_source:
1351 kmem_cache_free(epi_cache, epi);
1352
1353 return error;
1354}
1355
1356
1357
1358
1359
1360static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event)
1361{
1362 int pwake = 0;
1363 unsigned int revents;
1364 poll_table pt;
1365
1366 init_poll_funcptr(&pt, NULL);
1367
1368
1369
1370
1371
1372
1373 epi->event.events = event->events;
1374 epi->event.data = event->data;
1375 if (epi->event.events & EPOLLWAKEUP) {
1376 if (!ep_has_wakeup_source(epi))
1377 ep_create_wakeup_source(epi);
1378 } else if (ep_has_wakeup_source(epi)) {
1379 ep_destroy_wakeup_source(epi);
1380 }
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400 smp_mb();
1401
1402
1403
1404
1405
1406 revents = ep_item_poll(epi, &pt);
1407
1408
1409
1410
1411
1412 if (revents & event->events) {
1413 spin_lock_irq(&ep->lock);
1414 if (!ep_is_linked(&epi->rdllink)) {
1415 list_add_tail(&epi->rdllink, &ep->rdllist);
1416 ep_pm_stay_awake(epi);
1417
1418
1419 if (waitqueue_active(&ep->wq))
1420 wake_up_locked(&ep->wq);
1421 if (waitqueue_active(&ep->poll_wait))
1422 pwake++;
1423 }
1424 spin_unlock_irq(&ep->lock);
1425 }
1426
1427
1428 if (pwake)
1429 ep_poll_safewake(&ep->poll_wait);
1430
1431 return 0;
1432}
1433
1434static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
1435 void *priv)
1436{
1437 struct ep_send_events_data *esed = priv;
1438 int eventcnt;
1439 unsigned int revents;
1440 struct epitem *epi;
1441 struct epoll_event __user *uevent;
1442 struct wakeup_source *ws;
1443 poll_table pt;
1444
1445 init_poll_funcptr(&pt, NULL);
1446
1447
1448
1449
1450
1451
1452 for (eventcnt = 0, uevent = esed->events;
1453 !list_empty(head) && eventcnt < esed->maxevents;) {
1454 epi = list_first_entry(head, struct epitem, rdllink);
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465 ws = ep_wakeup_source(epi);
1466 if (ws) {
1467 if (ws->active)
1468 __pm_stay_awake(ep->ws);
1469 __pm_relax(ws);
1470 }
1471
1472 list_del_init(&epi->rdllink);
1473
1474 revents = ep_item_poll(epi, &pt);
1475
1476
1477
1478
1479
1480
1481
1482 if (revents) {
1483 if (__put_user(revents, &uevent->events) ||
1484 __put_user(epi->event.data, &uevent->data)) {
1485 list_add(&epi->rdllink, head);
1486 ep_pm_stay_awake(epi);
1487 return eventcnt ? eventcnt : -EFAULT;
1488 }
1489 eventcnt++;
1490 uevent++;
1491 if (epi->event.events & EPOLLONESHOT)
1492 epi->event.events &= EP_PRIVATE_BITS;
1493 else if (!(epi->event.events & EPOLLET)) {
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505 list_add_tail(&epi->rdllink, &ep->rdllist);
1506 ep_pm_stay_awake(epi);
1507 }
1508 }
1509 }
1510
1511 return eventcnt;
1512}
1513
1514static int ep_send_events(struct eventpoll *ep,
1515 struct epoll_event __user *events, int maxevents)
1516{
1517 struct ep_send_events_data esed;
1518
1519 esed.maxevents = maxevents;
1520 esed.events = events;
1521
1522 return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0);
1523}
1524
1525static inline struct timespec ep_set_mstimeout(long ms)
1526{
1527 struct timespec now, ts = {
1528 .tv_sec = ms / MSEC_PER_SEC,
1529 .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
1530 };
1531
1532 ktime_get_ts(&now);
1533 return timespec_add_safe(now, ts);
1534}
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
1554 int maxevents, long timeout)
1555{
1556 int res = 0, eavail, timed_out = 0;
1557 unsigned long flags;
1558 long slack = 0;
1559 wait_queue_t wait;
1560 ktime_t expires, *to = NULL;
1561
1562 if (timeout > 0) {
1563 struct timespec end_time = ep_set_mstimeout(timeout);
1564
1565 slack = select_estimate_accuracy(&end_time);
1566 to = &expires;
1567 *to = timespec_to_ktime(end_time);
1568 } else if (timeout == 0) {
1569
1570
1571
1572
1573 timed_out = 1;
1574 spin_lock_irqsave(&ep->lock, flags);
1575 goto check_events;
1576 }
1577
1578fetch_events:
1579 spin_lock_irqsave(&ep->lock, flags);
1580
1581 if (!ep_events_available(ep)) {
1582
1583
1584
1585
1586
1587 init_waitqueue_entry(&wait, current);
1588 __add_wait_queue_exclusive(&ep->wq, &wait);
1589
1590 for (;;) {
1591
1592
1593
1594
1595
1596 set_current_state(TASK_INTERRUPTIBLE);
1597 if (ep_events_available(ep) || timed_out)
1598 break;
1599 if (signal_pending(current)) {
1600 res = -EINTR;
1601 break;
1602 }
1603
1604 spin_unlock_irqrestore(&ep->lock, flags);
1605 if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
1606 timed_out = 1;
1607
1608 spin_lock_irqsave(&ep->lock, flags);
1609 }
1610 __remove_wait_queue(&ep->wq, &wait);
1611
1612 set_current_state(TASK_RUNNING);
1613 }
1614check_events:
1615
1616 eavail = ep_events_available(ep);
1617
1618 spin_unlock_irqrestore(&ep->lock, flags);
1619
1620
1621
1622
1623
1624
1625 if (!res && eavail &&
1626 !(res = ep_send_events(ep, events, maxevents)) && !timed_out)
1627 goto fetch_events;
1628
1629 return res;
1630}
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
1648{
1649 int error = 0;
1650 struct file *file = priv;
1651 struct eventpoll *ep = file->private_data;
1652 struct eventpoll *ep_tovisit;
1653 struct rb_node *rbp;
1654 struct epitem *epi;
1655
1656 mutex_lock_nested(&ep->mtx, call_nests + 1);
1657 ep->visited = 1;
1658 list_add(&ep->visited_list_link, &visited_list);
1659 for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
1660 epi = rb_entry(rbp, struct epitem, rbn);
1661 if (unlikely(is_file_epoll(epi->ffd.file))) {
1662 ep_tovisit = epi->ffd.file->private_data;
1663 if (ep_tovisit->visited)
1664 continue;
1665 error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1666 ep_loop_check_proc, epi->ffd.file,
1667 ep_tovisit, current);
1668 if (error != 0)
1669 break;
1670 } else {
1671
1672
1673
1674
1675
1676
1677
1678
1679 if (list_empty(&epi->ffd.file->f_tfile_llink))
1680 list_add(&epi->ffd.file->f_tfile_llink,
1681 &tfile_check_list);
1682 }
1683 }
1684 mutex_unlock(&ep->mtx);
1685
1686 return error;
1687}
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700static int ep_loop_check(struct eventpoll *ep, struct file *file)
1701{
1702 int ret;
1703 struct eventpoll *ep_cur, *ep_next;
1704
1705 ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1706 ep_loop_check_proc, file, ep, current);
1707
1708 list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
1709 visited_list_link) {
1710 ep_cur->visited = 0;
1711 list_del(&ep_cur->visited_list_link);
1712 }
1713 return ret;
1714}
1715
1716static void clear_tfile_check_list(void)
1717{
1718 struct file *file;
1719
1720
1721 while (!list_empty(&tfile_check_list)) {
1722 file = list_first_entry(&tfile_check_list, struct file,
1723 f_tfile_llink);
1724 list_del_init(&file->f_tfile_llink);
1725 }
1726 INIT_LIST_HEAD(&tfile_check_list);
1727}
1728
1729
1730
1731
1732SYSCALL_DEFINE1(epoll_create1, int, flags)
1733{
1734 int error, fd;
1735 struct eventpoll *ep = NULL;
1736 struct file *file;
1737
1738
1739 BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
1740
1741 if (flags & ~EPOLL_CLOEXEC)
1742 return -EINVAL;
1743
1744
1745
1746 error = ep_alloc(&ep);
1747 if (error < 0)
1748 return error;
1749
1750
1751
1752
1753 fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
1754 if (fd < 0) {
1755 error = fd;
1756 goto out_free_ep;
1757 }
1758 file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
1759 O_RDWR | (flags & O_CLOEXEC));
1760 if (IS_ERR(file)) {
1761 error = PTR_ERR(file);
1762 goto out_free_fd;
1763 }
1764 ep->file = file;
1765 fd_install(fd, file);
1766 return fd;
1767
1768out_free_fd:
1769 put_unused_fd(fd);
1770out_free_ep:
1771 ep_free(ep);
1772 return error;
1773}
1774
1775SYSCALL_DEFINE1(epoll_create, int, size)
1776{
1777 if (size <= 0)
1778 return -EINVAL;
1779
1780 return sys_epoll_create1(0);
1781}
1782
1783
1784
1785
1786
1787
1788SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
1789 struct epoll_event __user *, event)
1790{
1791 int error;
1792 int did_lock_epmutex = 0;
1793 struct file *file, *tfile;
1794 struct eventpoll *ep;
1795 struct epitem *epi;
1796 struct epoll_event epds;
1797
1798 error = -EFAULT;
1799 if (ep_op_has_event(op) &&
1800 copy_from_user(&epds, event, sizeof(struct epoll_event)))
1801 goto error_return;
1802
1803
1804 error = -EBADF;
1805 file = fget(epfd);
1806 if (!file)
1807 goto error_return;
1808
1809
1810 tfile = fget(fd);
1811 if (!tfile)
1812 goto error_fput;
1813
1814
1815 error = -EPERM;
1816 if (!tfile->f_op || !tfile->f_op->poll)
1817 goto error_tgt_fput;
1818
1819
1820 if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND))
1821 epds.events &= ~EPOLLWAKEUP;
1822
1823
1824
1825
1826
1827
1828 error = -EINVAL;
1829 if (file == tfile || !is_file_epoll(file))
1830 goto error_tgt_fput;
1831
1832
1833
1834
1835
1836 ep = file->private_data;
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850 if (op == EPOLL_CTL_ADD || op == EPOLL_CTL_DEL) {
1851 mutex_lock(&epmutex);
1852 did_lock_epmutex = 1;
1853 }
1854 if (op == EPOLL_CTL_ADD) {
1855 if (is_file_epoll(tfile)) {
1856 error = -ELOOP;
1857 if (ep_loop_check(ep, tfile) != 0) {
1858 clear_tfile_check_list();
1859 goto error_tgt_fput;
1860 }
1861 } else
1862 list_add(&tfile->f_tfile_llink, &tfile_check_list);
1863 }
1864
1865 mutex_lock_nested(&ep->mtx, 0);
1866
1867
1868
1869
1870
1871
1872 epi = ep_find(ep, tfile, fd);
1873
1874 error = -EINVAL;
1875 switch (op) {
1876 case EPOLL_CTL_ADD:
1877 if (!epi) {
1878 epds.events |= POLLERR | POLLHUP;
1879 error = ep_insert(ep, &epds, tfile, fd);
1880 } else
1881 error = -EEXIST;
1882 clear_tfile_check_list();
1883 break;
1884 case EPOLL_CTL_DEL:
1885 if (epi)
1886 error = ep_remove(ep, epi);
1887 else
1888 error = -ENOENT;
1889 break;
1890 case EPOLL_CTL_MOD:
1891 if (epi) {
1892 epds.events |= POLLERR | POLLHUP;
1893 error = ep_modify(ep, epi, &epds);
1894 } else
1895 error = -ENOENT;
1896 break;
1897 }
1898 mutex_unlock(&ep->mtx);
1899
1900error_tgt_fput:
1901 if (did_lock_epmutex)
1902 mutex_unlock(&epmutex);
1903
1904 fput(tfile);
1905error_fput:
1906 fput(file);
1907error_return:
1908
1909 return error;
1910}
1911
1912
1913
1914
1915
1916SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
1917 int, maxevents, int, timeout)
1918{
1919 int error;
1920 struct fd f;
1921 struct eventpoll *ep;
1922
1923
1924 if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
1925 return -EINVAL;
1926
1927
1928 if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event)))
1929 return -EFAULT;
1930
1931
1932 f = fdget(epfd);
1933 if (!f.file)
1934 return -EBADF;
1935
1936
1937
1938
1939
1940 error = -EINVAL;
1941 if (!is_file_epoll(f.file))
1942 goto error_fput;
1943
1944
1945
1946
1947
1948 ep = f.file->private_data;
1949
1950
1951 error = ep_poll(ep, events, maxevents, timeout);
1952
1953error_fput:
1954 fdput(f);
1955 return error;
1956}
1957
1958
1959
1960
1961
1962SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
1963 int, maxevents, int, timeout, const sigset_t __user *, sigmask,
1964 size_t, sigsetsize)
1965{
1966 int error;
1967 sigset_t ksigmask, sigsaved;
1968
1969
1970
1971
1972
1973 if (sigmask) {
1974 if (sigsetsize != sizeof(sigset_t))
1975 return -EINVAL;
1976 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1977 return -EFAULT;
1978 sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
1979 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1980 }
1981
1982 error = sys_epoll_wait(epfd, events, maxevents, timeout);
1983
1984
1985
1986
1987
1988
1989
1990 if (sigmask) {
1991 if (error == -EINTR) {
1992 memcpy(¤t->saved_sigmask, &sigsaved,
1993 sizeof(sigsaved));
1994 set_restore_sigmask();
1995 } else
1996 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1997 }
1998
1999 return error;
2000}
2001
2002#ifdef CONFIG_COMPAT
2003COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
2004 struct epoll_event __user *, events,
2005 int, maxevents, int, timeout,
2006 const compat_sigset_t __user *, sigmask,
2007 compat_size_t, sigsetsize)
2008{
2009 long err;
2010 compat_sigset_t csigmask;
2011 sigset_t ksigmask, sigsaved;
2012
2013
2014
2015
2016
2017 if (sigmask) {
2018 if (sigsetsize != sizeof(compat_sigset_t))
2019 return -EINVAL;
2020 if (copy_from_user(&csigmask, sigmask, sizeof(csigmask)))
2021 return -EFAULT;
2022 sigset_from_compat(&ksigmask, &csigmask);
2023 sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2024 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
2025 }
2026
2027 err = sys_epoll_wait(epfd, events, maxevents, timeout);
2028
2029
2030
2031
2032
2033
2034
2035 if (sigmask) {
2036 if (err == -EINTR) {
2037 memcpy(¤t->saved_sigmask, &sigsaved,
2038 sizeof(sigsaved));
2039 set_restore_sigmask();
2040 } else
2041 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
2042 }
2043
2044 return err;
2045}
2046#endif
2047
2048static int __init eventpoll_init(void)
2049{
2050 struct sysinfo si;
2051
2052 si_meminfo(&si);
2053
2054
2055
2056 max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
2057 EP_ITEM_COST;
2058 BUG_ON(max_user_watches < 0);
2059
2060
2061
2062
2063
2064 ep_nested_calls_init(&poll_loop_ncalls);
2065
2066
2067 ep_nested_calls_init(&poll_safewake_ncalls);
2068
2069
2070 ep_nested_calls_init(&poll_readywalk_ncalls);
2071
2072
2073
2074
2075
2076 BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128);
2077
2078
2079 epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
2080 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2081
2082
2083 pwq_cache = kmem_cache_create("eventpoll_pwq",
2084 sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL);
2085
2086 return 0;
2087}
2088fs_initcall(eventpoll_init);
2089