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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
382
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387
388
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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464
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 cond_resched();
743 }
744
745
746
747
748
749
750
751
752
753 mutex_lock(&ep->mtx);
754 while ((rbp = rb_first(&ep->rbr)) != NULL) {
755 epi = rb_entry(rbp, struct epitem, rbn);
756 ep_remove(ep, epi);
757 cond_resched();
758 }
759 mutex_unlock(&ep->mtx);
760
761 mutex_unlock(&epmutex);
762 mutex_destroy(&ep->mtx);
763 free_uid(ep->user);
764 wakeup_source_unregister(ep->ws);
765 kfree(ep);
766}
767
768static int ep_eventpoll_release(struct inode *inode, struct file *file)
769{
770 struct eventpoll *ep = file->private_data;
771
772 if (ep)
773 ep_free(ep);
774
775 return 0;
776}
777
778static inline unsigned int ep_item_poll(struct epitem *epi, poll_table *pt)
779{
780 pt->_key = epi->event.events;
781
782 return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & epi->event.events;
783}
784
785static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
786 void *priv)
787{
788 struct epitem *epi, *tmp;
789 poll_table pt;
790
791 init_poll_funcptr(&pt, NULL);
792
793 list_for_each_entry_safe(epi, tmp, head, rdllink) {
794 if (ep_item_poll(epi, &pt))
795 return POLLIN | POLLRDNORM;
796 else {
797
798
799
800
801
802 __pm_relax(ep_wakeup_source(epi));
803 list_del_init(&epi->rdllink);
804 }
805 }
806
807 return 0;
808}
809
810static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests)
811{
812 return ep_scan_ready_list(priv, ep_read_events_proc, NULL, call_nests + 1);
813}
814
815static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
816{
817 int pollflags;
818 struct eventpoll *ep = file->private_data;
819
820
821 poll_wait(file, &ep->poll_wait, wait);
822
823
824
825
826
827
828
829 pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS,
830 ep_poll_readyevents_proc, ep, ep, current);
831
832 return pollflags != -1 ? pollflags : 0;
833}
834
835#ifdef CONFIG_PROC_FS
836static int ep_show_fdinfo(struct seq_file *m, struct file *f)
837{
838 struct eventpoll *ep = f->private_data;
839 struct rb_node *rbp;
840 int ret = 0;
841
842 mutex_lock(&ep->mtx);
843 for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
844 struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
845
846 ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
847 epi->ffd.fd, epi->event.events,
848 (long long)epi->event.data);
849 if (ret)
850 break;
851 }
852 mutex_unlock(&ep->mtx);
853
854 return ret;
855}
856#endif
857
858
859static const struct file_operations eventpoll_fops = {
860#ifdef CONFIG_PROC_FS
861 .show_fdinfo = ep_show_fdinfo,
862#endif
863 .release = ep_eventpoll_release,
864 .poll = ep_eventpoll_poll,
865 .llseek = noop_llseek,
866};
867
868
869
870
871
872
873void eventpoll_release_file(struct file *file)
874{
875 struct list_head *lsthead = &file->f_ep_links;
876 struct eventpoll *ep;
877 struct epitem *epi;
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892 mutex_lock(&epmutex);
893
894 while (!list_empty(lsthead)) {
895 epi = list_first_entry(lsthead, struct epitem, fllink);
896
897 ep = epi->ep;
898 list_del_init(&epi->fllink);
899 mutex_lock_nested(&ep->mtx, 0);
900 ep_remove(ep, epi);
901 mutex_unlock(&ep->mtx);
902 }
903
904 mutex_unlock(&epmutex);
905}
906
907static int ep_alloc(struct eventpoll **pep)
908{
909 int error;
910 struct user_struct *user;
911 struct eventpoll *ep;
912
913 user = get_current_user();
914 error = -ENOMEM;
915 ep = kzalloc(sizeof(*ep), GFP_KERNEL);
916 if (unlikely(!ep))
917 goto free_uid;
918
919 spin_lock_init(&ep->lock);
920 mutex_init(&ep->mtx);
921 init_waitqueue_head(&ep->wq);
922 init_waitqueue_head(&ep->poll_wait);
923 INIT_LIST_HEAD(&ep->rdllist);
924 ep->rbr = RB_ROOT;
925 ep->ovflist = EP_UNACTIVE_PTR;
926 ep->user = user;
927
928 *pep = ep;
929
930 return 0;
931
932free_uid:
933 free_uid(user);
934 return error;
935}
936
937
938
939
940
941
942static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
943{
944 int kcmp;
945 struct rb_node *rbp;
946 struct epitem *epi, *epir = NULL;
947 struct epoll_filefd ffd;
948
949 ep_set_ffd(&ffd, file, fd);
950 for (rbp = ep->rbr.rb_node; rbp; ) {
951 epi = rb_entry(rbp, struct epitem, rbn);
952 kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
953 if (kcmp > 0)
954 rbp = rbp->rb_right;
955 else if (kcmp < 0)
956 rbp = rbp->rb_left;
957 else {
958 epir = epi;
959 break;
960 }
961 }
962
963 return epir;
964}
965
966
967
968
969
970
971static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
972{
973 int pwake = 0;
974 unsigned long flags;
975 struct epitem *epi = ep_item_from_wait(wait);
976 struct eventpoll *ep = epi->ep;
977
978 if ((unsigned long)key & POLLFREE) {
979 ep_pwq_from_wait(wait)->whead = NULL;
980
981
982
983
984
985
986 list_del_init(&wait->task_list);
987 }
988
989 spin_lock_irqsave(&ep->lock, flags);
990
991
992
993
994
995
996
997 if (!(epi->event.events & ~EP_PRIVATE_BITS))
998 goto out_unlock;
999
1000
1001
1002
1003
1004
1005
1006 if (key && !((unsigned long) key & epi->event.events))
1007 goto out_unlock;
1008
1009
1010
1011
1012
1013
1014
1015 if (unlikely(ep->ovflist != EP_UNACTIVE_PTR)) {
1016 if (epi->next == EP_UNACTIVE_PTR) {
1017 epi->next = ep->ovflist;
1018 ep->ovflist = epi;
1019 if (epi->ws) {
1020
1021
1022
1023
1024 __pm_stay_awake(ep->ws);
1025 }
1026
1027 }
1028 goto out_unlock;
1029 }
1030
1031
1032 if (!ep_is_linked(&epi->rdllink)) {
1033 list_add_tail(&epi->rdllink, &ep->rdllist);
1034 ep_pm_stay_awake_rcu(epi);
1035 }
1036
1037
1038
1039
1040
1041 if (waitqueue_active(&ep->wq))
1042 wake_up_locked(&ep->wq);
1043 if (waitqueue_active(&ep->poll_wait))
1044 pwake++;
1045
1046out_unlock:
1047 spin_unlock_irqrestore(&ep->lock, flags);
1048
1049
1050 if (pwake)
1051 ep_poll_safewake(&ep->poll_wait);
1052
1053 return 1;
1054}
1055
1056
1057
1058
1059
1060static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
1061 poll_table *pt)
1062{
1063 struct epitem *epi = ep_item_from_epqueue(pt);
1064 struct eppoll_entry *pwq;
1065
1066 if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
1067 init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
1068 pwq->whead = whead;
1069 pwq->base = epi;
1070 add_wait_queue(whead, &pwq->wait);
1071 list_add_tail(&pwq->llink, &epi->pwqlist);
1072 epi->nwait++;
1073 } else {
1074
1075 epi->nwait = -1;
1076 }
1077}
1078
1079static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
1080{
1081 int kcmp;
1082 struct rb_node **p = &ep->rbr.rb_node, *parent = NULL;
1083 struct epitem *epic;
1084
1085 while (*p) {
1086 parent = *p;
1087 epic = rb_entry(parent, struct epitem, rbn);
1088 kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
1089 if (kcmp > 0)
1090 p = &parent->rb_right;
1091 else
1092 p = &parent->rb_left;
1093 }
1094 rb_link_node(&epi->rbn, parent, p);
1095 rb_insert_color(&epi->rbn, &ep->rbr);
1096}
1097
1098
1099
1100#define PATH_ARR_SIZE 5
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
1113static int path_count[PATH_ARR_SIZE];
1114
1115static int path_count_inc(int nests)
1116{
1117
1118 if (nests == 0)
1119 return 0;
1120
1121 if (++path_count[nests] > path_limits[nests])
1122 return -1;
1123 return 0;
1124}
1125
1126static void path_count_init(void)
1127{
1128 int i;
1129
1130 for (i = 0; i < PATH_ARR_SIZE; i++)
1131 path_count[i] = 0;
1132}
1133
1134static int reverse_path_check_proc(void *priv, void *cookie, int call_nests)
1135{
1136 int error = 0;
1137 struct file *file = priv;
1138 struct file *child_file;
1139 struct epitem *epi;
1140
1141 list_for_each_entry(epi, &file->f_ep_links, fllink) {
1142 child_file = epi->ep->file;
1143 if (is_file_epoll(child_file)) {
1144 if (list_empty(&child_file->f_ep_links)) {
1145 if (path_count_inc(call_nests)) {
1146 error = -1;
1147 break;
1148 }
1149 } else {
1150 error = ep_call_nested(&poll_loop_ncalls,
1151 EP_MAX_NESTS,
1152 reverse_path_check_proc,
1153 child_file, child_file,
1154 current);
1155 }
1156 if (error != 0)
1157 break;
1158 } else {
1159 printk(KERN_ERR "reverse_path_check_proc: "
1160 "file is not an ep!\n");
1161 }
1162 }
1163 return error;
1164}
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176static int reverse_path_check(void)
1177{
1178 int error = 0;
1179 struct file *current_file;
1180
1181
1182 list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {
1183 path_count_init();
1184 error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1185 reverse_path_check_proc, current_file,
1186 current_file, current);
1187 if (error)
1188 break;
1189 }
1190 return error;
1191}
1192
1193static int ep_create_wakeup_source(struct epitem *epi)
1194{
1195 const char *name;
1196 struct wakeup_source *ws;
1197
1198 if (!epi->ep->ws) {
1199 epi->ep->ws = wakeup_source_register("eventpoll");
1200 if (!epi->ep->ws)
1201 return -ENOMEM;
1202 }
1203
1204 name = epi->ffd.file->f_path.dentry->d_name.name;
1205 ws = wakeup_source_register(name);
1206
1207 if (!ws)
1208 return -ENOMEM;
1209 rcu_assign_pointer(epi->ws, ws);
1210
1211 return 0;
1212}
1213
1214
1215static noinline void ep_destroy_wakeup_source(struct epitem *epi)
1216{
1217 struct wakeup_source *ws = ep_wakeup_source(epi);
1218
1219 RCU_INIT_POINTER(epi->ws, NULL);
1220
1221
1222
1223
1224
1225
1226 synchronize_rcu();
1227 wakeup_source_unregister(ws);
1228}
1229
1230
1231
1232
1233static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
1234 struct file *tfile, int fd)
1235{
1236 int error, revents, pwake = 0;
1237 unsigned long flags;
1238 long user_watches;
1239 struct epitem *epi;
1240 struct ep_pqueue epq;
1241
1242 user_watches = atomic_long_read(&ep->user->epoll_watches);
1243 if (unlikely(user_watches >= max_user_watches))
1244 return -ENOSPC;
1245 if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
1246 return -ENOMEM;
1247
1248
1249 INIT_LIST_HEAD(&epi->rdllink);
1250 INIT_LIST_HEAD(&epi->fllink);
1251 INIT_LIST_HEAD(&epi->pwqlist);
1252 epi->ep = ep;
1253 ep_set_ffd(&epi->ffd, tfile, fd);
1254 epi->event = *event;
1255 epi->nwait = 0;
1256 epi->next = EP_UNACTIVE_PTR;
1257 if (epi->event.events & EPOLLWAKEUP) {
1258 error = ep_create_wakeup_source(epi);
1259 if (error)
1260 goto error_create_wakeup_source;
1261 } else {
1262 RCU_INIT_POINTER(epi->ws, NULL);
1263 }
1264
1265
1266 epq.epi = epi;
1267 init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
1268
1269
1270
1271
1272
1273
1274
1275
1276 revents = ep_item_poll(epi, &epq.pt);
1277
1278
1279
1280
1281
1282
1283 error = -ENOMEM;
1284 if (epi->nwait < 0)
1285 goto error_unregister;
1286
1287
1288 spin_lock(&tfile->f_lock);
1289 list_add_tail(&epi->fllink, &tfile->f_ep_links);
1290 spin_unlock(&tfile->f_lock);
1291
1292
1293
1294
1295
1296 ep_rbtree_insert(ep, epi);
1297
1298
1299 error = -EINVAL;
1300 if (reverse_path_check())
1301 goto error_remove_epi;
1302
1303
1304 spin_lock_irqsave(&ep->lock, flags);
1305
1306
1307 if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) {
1308 list_add_tail(&epi->rdllink, &ep->rdllist);
1309 ep_pm_stay_awake(epi);
1310
1311
1312 if (waitqueue_active(&ep->wq))
1313 wake_up_locked(&ep->wq);
1314 if (waitqueue_active(&ep->poll_wait))
1315 pwake++;
1316 }
1317
1318 spin_unlock_irqrestore(&ep->lock, flags);
1319
1320 atomic_long_inc(&ep->user->epoll_watches);
1321
1322
1323 if (pwake)
1324 ep_poll_safewake(&ep->poll_wait);
1325
1326 return 0;
1327
1328error_remove_epi:
1329 spin_lock(&tfile->f_lock);
1330 if (ep_is_linked(&epi->fllink))
1331 list_del_init(&epi->fllink);
1332 spin_unlock(&tfile->f_lock);
1333
1334 rb_erase(&epi->rbn, &ep->rbr);
1335
1336error_unregister:
1337 ep_unregister_pollwait(ep, epi);
1338
1339
1340
1341
1342
1343
1344
1345 spin_lock_irqsave(&ep->lock, flags);
1346 if (ep_is_linked(&epi->rdllink))
1347 list_del_init(&epi->rdllink);
1348 spin_unlock_irqrestore(&ep->lock, flags);
1349
1350 wakeup_source_unregister(ep_wakeup_source(epi));
1351
1352error_create_wakeup_source:
1353 kmem_cache_free(epi_cache, epi);
1354
1355 return error;
1356}
1357
1358
1359
1360
1361
1362static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event)
1363{
1364 int pwake = 0;
1365 unsigned int revents;
1366 poll_table pt;
1367
1368 init_poll_funcptr(&pt, NULL);
1369
1370
1371
1372
1373
1374
1375 epi->event.events = event->events;
1376 epi->event.data = event->data;
1377 if (epi->event.events & EPOLLWAKEUP) {
1378 if (!ep_has_wakeup_source(epi))
1379 ep_create_wakeup_source(epi);
1380 } else if (ep_has_wakeup_source(epi)) {
1381 ep_destroy_wakeup_source(epi);
1382 }
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402 smp_mb();
1403
1404
1405
1406
1407
1408 revents = ep_item_poll(epi, &pt);
1409
1410
1411
1412
1413
1414 if (revents & event->events) {
1415 spin_lock_irq(&ep->lock);
1416 if (!ep_is_linked(&epi->rdllink)) {
1417 list_add_tail(&epi->rdllink, &ep->rdllist);
1418 ep_pm_stay_awake(epi);
1419
1420
1421 if (waitqueue_active(&ep->wq))
1422 wake_up_locked(&ep->wq);
1423 if (waitqueue_active(&ep->poll_wait))
1424 pwake++;
1425 }
1426 spin_unlock_irq(&ep->lock);
1427 }
1428
1429
1430 if (pwake)
1431 ep_poll_safewake(&ep->poll_wait);
1432
1433 return 0;
1434}
1435
1436static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
1437 void *priv)
1438{
1439 struct ep_send_events_data *esed = priv;
1440 int eventcnt;
1441 unsigned int revents;
1442 struct epitem *epi;
1443 struct epoll_event __user *uevent;
1444 struct wakeup_source *ws;
1445 poll_table pt;
1446
1447 init_poll_funcptr(&pt, NULL);
1448
1449
1450
1451
1452
1453
1454 for (eventcnt = 0, uevent = esed->events;
1455 !list_empty(head) && eventcnt < esed->maxevents;) {
1456 epi = list_first_entry(head, struct epitem, rdllink);
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467 ws = ep_wakeup_source(epi);
1468 if (ws) {
1469 if (ws->active)
1470 __pm_stay_awake(ep->ws);
1471 __pm_relax(ws);
1472 }
1473
1474 list_del_init(&epi->rdllink);
1475
1476 revents = ep_item_poll(epi, &pt);
1477
1478
1479
1480
1481
1482
1483
1484 if (revents) {
1485 if (__put_user(revents, &uevent->events) ||
1486 __put_user(epi->event.data, &uevent->data)) {
1487 list_add(&epi->rdllink, head);
1488 ep_pm_stay_awake(epi);
1489 return eventcnt ? eventcnt : -EFAULT;
1490 }
1491 eventcnt++;
1492 uevent++;
1493 if (epi->event.events & EPOLLONESHOT)
1494 epi->event.events &= EP_PRIVATE_BITS;
1495 else if (!(epi->event.events & EPOLLET)) {
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507 list_add_tail(&epi->rdllink, &ep->rdllist);
1508 ep_pm_stay_awake(epi);
1509 }
1510 }
1511 }
1512
1513 return eventcnt;
1514}
1515
1516static int ep_send_events(struct eventpoll *ep,
1517 struct epoll_event __user *events, int maxevents)
1518{
1519 struct ep_send_events_data esed;
1520
1521 esed.maxevents = maxevents;
1522 esed.events = events;
1523
1524 return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0);
1525}
1526
1527static inline struct timespec ep_set_mstimeout(long ms)
1528{
1529 struct timespec now, ts = {
1530 .tv_sec = ms / MSEC_PER_SEC,
1531 .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
1532 };
1533
1534 ktime_get_ts(&now);
1535 return timespec_add_safe(now, ts);
1536}
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
1556 int maxevents, long timeout)
1557{
1558 int res = 0, eavail, timed_out = 0;
1559 unsigned long flags;
1560 long slack = 0;
1561 wait_queue_t wait;
1562 ktime_t expires, *to = NULL;
1563
1564 if (timeout > 0) {
1565 struct timespec end_time = ep_set_mstimeout(timeout);
1566
1567 slack = select_estimate_accuracy(&end_time);
1568 to = &expires;
1569 *to = timespec_to_ktime(end_time);
1570 } else if (timeout == 0) {
1571
1572
1573
1574
1575 timed_out = 1;
1576 spin_lock_irqsave(&ep->lock, flags);
1577 goto check_events;
1578 }
1579
1580fetch_events:
1581 spin_lock_irqsave(&ep->lock, flags);
1582
1583 if (!ep_events_available(ep)) {
1584
1585
1586
1587
1588
1589 init_waitqueue_entry(&wait, current);
1590 __add_wait_queue_exclusive(&ep->wq, &wait);
1591
1592 for (;;) {
1593
1594
1595
1596
1597
1598 set_current_state(TASK_INTERRUPTIBLE);
1599 if (ep_events_available(ep) || timed_out)
1600 break;
1601 if (signal_pending(current)) {
1602 res = -EINTR;
1603 break;
1604 }
1605
1606 spin_unlock_irqrestore(&ep->lock, flags);
1607 if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
1608 timed_out = 1;
1609
1610 spin_lock_irqsave(&ep->lock, flags);
1611 }
1612 __remove_wait_queue(&ep->wq, &wait);
1613
1614 set_current_state(TASK_RUNNING);
1615 }
1616check_events:
1617
1618 eavail = ep_events_available(ep);
1619
1620 spin_unlock_irqrestore(&ep->lock, flags);
1621
1622
1623
1624
1625
1626
1627 if (!res && eavail &&
1628 !(res = ep_send_events(ep, events, maxevents)) && !timed_out)
1629 goto fetch_events;
1630
1631 return res;
1632}
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
1650{
1651 int error = 0;
1652 struct file *file = priv;
1653 struct eventpoll *ep = file->private_data;
1654 struct eventpoll *ep_tovisit;
1655 struct rb_node *rbp;
1656 struct epitem *epi;
1657
1658 mutex_lock_nested(&ep->mtx, call_nests + 1);
1659 ep->visited = 1;
1660 list_add(&ep->visited_list_link, &visited_list);
1661 for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
1662 epi = rb_entry(rbp, struct epitem, rbn);
1663 if (unlikely(is_file_epoll(epi->ffd.file))) {
1664 ep_tovisit = epi->ffd.file->private_data;
1665 if (ep_tovisit->visited)
1666 continue;
1667 error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1668 ep_loop_check_proc, epi->ffd.file,
1669 ep_tovisit, current);
1670 if (error != 0)
1671 break;
1672 } else {
1673
1674
1675
1676
1677
1678
1679
1680
1681 if (list_empty(&epi->ffd.file->f_tfile_llink))
1682 list_add(&epi->ffd.file->f_tfile_llink,
1683 &tfile_check_list);
1684 }
1685 }
1686 mutex_unlock(&ep->mtx);
1687
1688 return error;
1689}
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702static int ep_loop_check(struct eventpoll *ep, struct file *file)
1703{
1704 int ret;
1705 struct eventpoll *ep_cur, *ep_next;
1706
1707 ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
1708 ep_loop_check_proc, file, ep, current);
1709
1710 list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
1711 visited_list_link) {
1712 ep_cur->visited = 0;
1713 list_del(&ep_cur->visited_list_link);
1714 }
1715 return ret;
1716}
1717
1718static void clear_tfile_check_list(void)
1719{
1720 struct file *file;
1721
1722
1723 while (!list_empty(&tfile_check_list)) {
1724 file = list_first_entry(&tfile_check_list, struct file,
1725 f_tfile_llink);
1726 list_del_init(&file->f_tfile_llink);
1727 }
1728 INIT_LIST_HEAD(&tfile_check_list);
1729}
1730
1731
1732
1733
1734SYSCALL_DEFINE1(epoll_create1, int, flags)
1735{
1736 int error, fd;
1737 struct eventpoll *ep = NULL;
1738 struct file *file;
1739
1740
1741 BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
1742
1743 if (flags & ~EPOLL_CLOEXEC)
1744 return -EINVAL;
1745
1746
1747
1748 error = ep_alloc(&ep);
1749 if (error < 0)
1750 return error;
1751
1752
1753
1754
1755 fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
1756 if (fd < 0) {
1757 error = fd;
1758 goto out_free_ep;
1759 }
1760 file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
1761 O_RDWR | (flags & O_CLOEXEC));
1762 if (IS_ERR(file)) {
1763 error = PTR_ERR(file);
1764 goto out_free_fd;
1765 }
1766 ep->file = file;
1767 fd_install(fd, file);
1768 return fd;
1769
1770out_free_fd:
1771 put_unused_fd(fd);
1772out_free_ep:
1773 ep_free(ep);
1774 return error;
1775}
1776
1777SYSCALL_DEFINE1(epoll_create, int, size)
1778{
1779 if (size <= 0)
1780 return -EINVAL;
1781
1782 return sys_epoll_create1(0);
1783}
1784
1785
1786
1787
1788
1789
1790SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
1791 struct epoll_event __user *, event)
1792{
1793 int error;
1794 int did_lock_epmutex = 0;
1795 struct fd f, tf;
1796 struct eventpoll *ep;
1797 struct epitem *epi;
1798 struct epoll_event epds;
1799
1800 error = -EFAULT;
1801 if (ep_op_has_event(op) &&
1802 copy_from_user(&epds, event, sizeof(struct epoll_event)))
1803 goto error_return;
1804
1805 error = -EBADF;
1806 f = fdget(epfd);
1807 if (!f.file)
1808 goto error_return;
1809
1810
1811 tf = fdget(fd);
1812 if (!tf.file)
1813 goto error_fput;
1814
1815
1816 error = -EPERM;
1817 if (!tf.file->f_op || !tf.file->f_op->poll)
1818 goto error_tgt_fput;
1819
1820
1821 if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND))
1822 epds.events &= ~EPOLLWAKEUP;
1823
1824
1825
1826
1827
1828
1829 error = -EINVAL;
1830 if (f.file == tf.file || !is_file_epoll(f.file))
1831 goto error_tgt_fput;
1832
1833
1834
1835
1836
1837 ep = f.file->private_data;
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851 if (op == EPOLL_CTL_ADD || op == EPOLL_CTL_DEL) {
1852 mutex_lock(&epmutex);
1853 did_lock_epmutex = 1;
1854 }
1855 if (op == EPOLL_CTL_ADD) {
1856 if (is_file_epoll(tf.file)) {
1857 error = -ELOOP;
1858 if (ep_loop_check(ep, tf.file) != 0) {
1859 clear_tfile_check_list();
1860 goto error_tgt_fput;
1861 }
1862 } else
1863 list_add(&tf.file->f_tfile_llink, &tfile_check_list);
1864 }
1865
1866 mutex_lock_nested(&ep->mtx, 0);
1867
1868
1869
1870
1871
1872
1873 epi = ep_find(ep, tf.file, fd);
1874
1875 error = -EINVAL;
1876 switch (op) {
1877 case EPOLL_CTL_ADD:
1878 if (!epi) {
1879 epds.events |= POLLERR | POLLHUP;
1880 error = ep_insert(ep, &epds, tf.file, fd);
1881 } else
1882 error = -EEXIST;
1883 clear_tfile_check_list();
1884 break;
1885 case EPOLL_CTL_DEL:
1886 if (epi)
1887 error = ep_remove(ep, epi);
1888 else
1889 error = -ENOENT;
1890 break;
1891 case EPOLL_CTL_MOD:
1892 if (epi) {
1893 epds.events |= POLLERR | POLLHUP;
1894 error = ep_modify(ep, epi, &epds);
1895 } else
1896 error = -ENOENT;
1897 break;
1898 }
1899 mutex_unlock(&ep->mtx);
1900
1901error_tgt_fput:
1902 if (did_lock_epmutex)
1903 mutex_unlock(&epmutex);
1904
1905 fdput(tf);
1906error_fput:
1907 fdput(f);
1908error_return:
1909
1910 return error;
1911}
1912
1913
1914
1915
1916
1917SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
1918 int, maxevents, int, timeout)
1919{
1920 int error;
1921 struct fd f;
1922 struct eventpoll *ep;
1923
1924
1925 if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
1926 return -EINVAL;
1927
1928
1929 if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event)))
1930 return -EFAULT;
1931
1932
1933 f = fdget(epfd);
1934 if (!f.file)
1935 return -EBADF;
1936
1937
1938
1939
1940
1941 error = -EINVAL;
1942 if (!is_file_epoll(f.file))
1943 goto error_fput;
1944
1945
1946
1947
1948
1949 ep = f.file->private_data;
1950
1951
1952 error = ep_poll(ep, events, maxevents, timeout);
1953
1954error_fput:
1955 fdput(f);
1956 return error;
1957}
1958
1959
1960
1961
1962
1963SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
1964 int, maxevents, int, timeout, const sigset_t __user *, sigmask,
1965 size_t, sigsetsize)
1966{
1967 int error;
1968 sigset_t ksigmask, sigsaved;
1969
1970
1971
1972
1973
1974 if (sigmask) {
1975 if (sigsetsize != sizeof(sigset_t))
1976 return -EINVAL;
1977 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1978 return -EFAULT;
1979 sigsaved = current->blocked;
1980 set_current_blocked(&ksigmask);
1981 }
1982
1983 error = sys_epoll_wait(epfd, events, maxevents, timeout);
1984
1985
1986
1987
1988
1989
1990
1991 if (sigmask) {
1992 if (error == -EINTR) {
1993 memcpy(¤t->saved_sigmask, &sigsaved,
1994 sizeof(sigsaved));
1995 set_restore_sigmask();
1996 } else
1997 set_current_blocked(&sigsaved);
1998 }
1999
2000 return error;
2001}
2002
2003#ifdef CONFIG_COMPAT
2004COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
2005 struct epoll_event __user *, events,
2006 int, maxevents, int, timeout,
2007 const compat_sigset_t __user *, sigmask,
2008 compat_size_t, sigsetsize)
2009{
2010 long err;
2011 compat_sigset_t csigmask;
2012 sigset_t ksigmask, sigsaved;
2013
2014
2015
2016
2017
2018 if (sigmask) {
2019 if (sigsetsize != sizeof(compat_sigset_t))
2020 return -EINVAL;
2021 if (copy_from_user(&csigmask, sigmask, sizeof(csigmask)))
2022 return -EFAULT;
2023 sigset_from_compat(&ksigmask, &csigmask);
2024 sigsaved = current->blocked;
2025 set_current_blocked(&ksigmask);
2026 }
2027
2028 err = sys_epoll_wait(epfd, events, maxevents, timeout);
2029
2030
2031
2032
2033
2034
2035
2036 if (sigmask) {
2037 if (err == -EINTR) {
2038 memcpy(¤t->saved_sigmask, &sigsaved,
2039 sizeof(sigsaved));
2040 set_restore_sigmask();
2041 } else
2042 set_current_blocked(&sigsaved);
2043 }
2044
2045 return err;
2046}
2047#endif
2048
2049static int __init eventpoll_init(void)
2050{
2051 struct sysinfo si;
2052
2053 si_meminfo(&si);
2054
2055
2056
2057 max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
2058 EP_ITEM_COST;
2059 BUG_ON(max_user_watches < 0);
2060
2061
2062
2063
2064
2065 ep_nested_calls_init(&poll_loop_ncalls);
2066
2067
2068 ep_nested_calls_init(&poll_safewake_ncalls);
2069
2070
2071 ep_nested_calls_init(&poll_readywalk_ncalls);
2072
2073
2074
2075
2076
2077 BUILD_BUG_ON(sizeof(void *) <= 8 && sizeof(struct epitem) > 128);
2078
2079
2080 epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
2081 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2082
2083
2084 pwq_cache = kmem_cache_create("eventpoll_pwq",
2085 sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL);
2086
2087 return 0;
2088}
2089fs_initcall(eventpoll_init);
2090