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kernel - Fix swapcache cleaning issue
[dragonfly.git] / sys / kern / kern_event.c
blob3203c49d18b322071e0955577d40366e50746ad1
1 /*-
2 * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: src/sys/kern/kern_event.c,v 1.2.2.10 2004/04/04 07:03:14 cperciva Exp $
27 */
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/proc.h>
33 #include <sys/malloc.h>
34 #include <sys/unistd.h>
35 #include <sys/file.h>
36 #include <sys/lock.h>
37 #include <sys/fcntl.h>
38 #include <sys/queue.h>
39 #include <sys/event.h>
40 #include <sys/eventvar.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/socketvar.h>
44 #include <sys/stat.h>
45 #include <sys/sysctl.h>
46 #include <sys/sysproto.h>
47 #include <sys/thread.h>
48 #include <sys/uio.h>
49 #include <sys/signalvar.h>
50 #include <sys/filio.h>
51 #include <sys/ktr.h>
52 #include <sys/spinlock.h>
53
54 #include <sys/thread2.h>
55 #include <sys/file2.h>
56 #include <sys/mplock2.h>
57 #include <sys/spinlock2.h>
58
59 #define EVENT_REGISTER 1
60 #define EVENT_PROCESS 2
61
62 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
63
64 struct kevent_copyin_args {
65 struct kevent_args *ka;
66 int pchanges;
67 };
68
69 #define KNOTE_CACHE_MAX 8
70
71 struct knote_cache_list {
72 struct klist knote_cache;
73 int knote_cache_cnt;
74 } __cachealign;
75
76 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
77 struct knote *marker, int closedcounter);
78 static int kqueue_read(struct file *fp, struct uio *uio,
79 struct ucred *cred, int flags);
80 static int kqueue_write(struct file *fp, struct uio *uio,
81 struct ucred *cred, int flags);
82 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
83 struct ucred *cred, struct sysmsg *msg);
84 static int kqueue_kqfilter(struct file *fp, struct knote *kn);
85 static int kqueue_stat(struct file *fp, struct stat *st,
86 struct ucred *cred);
87 static int kqueue_close(struct file *fp);
88 static void kqueue_wakeup(struct kqueue *kq);
89 static int filter_attach(struct knote *kn);
90 static int filter_event(struct knote *kn, long hint);
91
92 /*
93 * MPSAFE
94 */
95 static struct fileops kqueueops = {
96 .fo_read = kqueue_read,
97 .fo_write = kqueue_write,
98 .fo_ioctl = kqueue_ioctl,
99 .fo_kqfilter = kqueue_kqfilter,
100 .fo_stat = kqueue_stat,
101 .fo_close = kqueue_close,
102 .fo_shutdown = nofo_shutdown
103 };
104
105 static void knote_attach(struct knote *kn);
106 static void knote_drop(struct knote *kn);
107 static void knote_detach_and_drop(struct knote *kn);
108 static void knote_enqueue(struct knote *kn);
109 static void knote_dequeue(struct knote *kn);
110 static struct knote *knote_alloc(void);
111 static void knote_free(struct knote *kn);
112
113 static void precise_sleep_intr(systimer_t info, int in_ipi,
114 struct intrframe *frame);
115 static int precise_sleep(void *ident, int flags, const char *wmesg,
116 int us);
117
118 static void filt_kqdetach(struct knote *kn);
119 static int filt_kqueue(struct knote *kn, long hint);
120 static int filt_procattach(struct knote *kn);
121 static void filt_procdetach(struct knote *kn);
122 static int filt_proc(struct knote *kn, long hint);
123 static int filt_fileattach(struct knote *kn);
124 static void filt_timerexpire(void *knx);
125 static int filt_timerattach(struct knote *kn);
126 static void filt_timerdetach(struct knote *kn);
127 static int filt_timer(struct knote *kn, long hint);
128 static int filt_userattach(struct knote *kn);
129 static void filt_userdetach(struct knote *kn);
130 static int filt_user(struct knote *kn, long hint);
131 static void filt_usertouch(struct knote *kn, struct kevent *kev,
132 u_long type);
133 static int filt_fsattach(struct knote *kn);
134 static void filt_fsdetach(struct knote *kn);
135 static int filt_fs(struct knote *kn, long hint);
136
137 static struct filterops file_filtops =
138 { FILTEROP_ISFD | FILTEROP_MPSAFE, filt_fileattach, NULL, NULL };
139 static struct filterops kqread_filtops =
140 { FILTEROP_ISFD | FILTEROP_MPSAFE, NULL, filt_kqdetach, filt_kqueue };
141 static struct filterops proc_filtops =
142 { FILTEROP_MPSAFE, filt_procattach, filt_procdetach, filt_proc };
143 static struct filterops timer_filtops =
144 { FILTEROP_MPSAFE, filt_timerattach, filt_timerdetach, filt_timer };
145 static struct filterops user_filtops =
146 { FILTEROP_MPSAFE, filt_userattach, filt_userdetach, filt_user };
147 static struct filterops fs_filtops =
148 { FILTEROP_MPSAFE, filt_fsattach, filt_fsdetach, filt_fs };
149
150 static int kq_ncallouts = 0;
151 static int kq_calloutmax = (4 * 1024);
152 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
153 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
154 static int kq_checkloop = 1000000;
155 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW,
156 &kq_checkloop, 0, "Maximum number of loops for kqueue scan");
157 static int kq_sleep_threshold = 20000;
158 SYSCTL_INT(_kern, OID_AUTO, kq_sleep_threshold, CTLFLAG_RW,
159 &kq_sleep_threshold, 0, "Minimum sleep duration without busy-looping");
160
161 #define KNOTE_ACTIVATE(kn) do { \
162 kn->kn_status |= KN_ACTIVE; \
163 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \
164 knote_enqueue(kn); \
165 } while(0)
166
167 #define KN_HASHSIZE 64 /* XXX should be tunable */
168 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask))
169
170 extern struct filterops aio_filtops;
171 extern struct filterops sig_filtops;
172
173 /*
174 * Table for for all system-defined filters.
175 */
176 static struct filterops *sysfilt_ops[] = {
177 &file_filtops, /* EVFILT_READ */
178 &file_filtops, /* EVFILT_WRITE */
179 &aio_filtops, /* EVFILT_AIO */
180 &file_filtops, /* EVFILT_VNODE */
181 &proc_filtops, /* EVFILT_PROC */
182 &sig_filtops, /* EVFILT_SIGNAL */
183 &timer_filtops, /* EVFILT_TIMER */
184 &file_filtops, /* EVFILT_EXCEPT */
185 &user_filtops, /* EVFILT_USER */
186 &fs_filtops, /* EVFILT_FS */
187 };
188
189 static struct knote_cache_list knote_cache_lists[MAXCPU];
190
191 /*
192 * Acquire a knote, return non-zero on success, 0 on failure.
193 *
194 * If we cannot acquire the knote we sleep and return 0. The knote
195 * may be stale on return in this case and the caller must restart
196 * whatever loop they are in.
197 *
198 * Related kq token must be held.
199 */
200 static __inline int
201 knote_acquire(struct knote *kn)
202 {
203 if (kn->kn_status & KN_PROCESSING) {
204 kn->kn_status |= KN_WAITING | KN_REPROCESS;
205 tsleep(kn, 0, "kqepts", hz);
206 /* knote may be stale now */
207 return(0);
208 }
209 kn->kn_status |= KN_PROCESSING;
210 return(1);
211 }
212
213 /*
214 * Release an acquired knote, clearing KN_PROCESSING and handling any
215 * KN_REPROCESS events.
216 *
217 * Caller must be holding the related kq token
218 *
219 * Non-zero is returned if the knote is destroyed or detached.
220 */
221 static __inline int
222 knote_release(struct knote *kn)
223 {
224 int ret;
225
226 while (kn->kn_status & KN_REPROCESS) {
227 kn->kn_status &= ~KN_REPROCESS;
228 if (kn->kn_status & KN_WAITING) {
229 kn->kn_status &= ~KN_WAITING;
230 wakeup(kn);
231 }
232 if (kn->kn_status & KN_DELETING) {
233 knote_detach_and_drop(kn);
234 return(1);
235 /* NOT REACHED */
236 }
237 if (filter_event(kn, 0))
238 KNOTE_ACTIVATE(kn);
239 }
240 if (kn->kn_status & KN_DETACHED)
241 ret = 1;
242 else
243 ret = 0;
244 kn->kn_status &= ~KN_PROCESSING;
245 /* kn should not be accessed anymore */
246 return ret;
247 }
248
249 static int
250 filt_fileattach(struct knote *kn)
251 {
252 return (fo_kqfilter(kn->kn_fp, kn));
253 }
254
255 /*
256 * MPSAFE
257 */
258 static int
259 kqueue_kqfilter(struct file *fp, struct knote *kn)
260 {
261 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
262
263 if (kn->kn_filter != EVFILT_READ)
264 return (EOPNOTSUPP);
265
266 kn->kn_fop = &kqread_filtops;
267 knote_insert(&kq->kq_kqinfo.ki_note, kn);
268 return (0);
269 }
270
271 static void
272 filt_kqdetach(struct knote *kn)
273 {
274 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
275
276 knote_remove(&kq->kq_kqinfo.ki_note, kn);
277 }
278
279 /*ARGSUSED*/
280 static int
281 filt_kqueue(struct knote *kn, long hint)
282 {
283 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
284
285 kn->kn_data = kq->kq_count;
286 return (kn->kn_data > 0);
287 }
288
289 static int
290 filt_procattach(struct knote *kn)
291 {
292 struct proc *p;
293 int immediate;
294
295 immediate = 0;
296 p = pfind(kn->kn_id);
297 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
298 p = zpfind(kn->kn_id);
299 immediate = 1;
300 }
301 if (p == NULL) {
302 return (ESRCH);
303 }
304 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) {
305 if (p)
306 PRELE(p);
307 return (EACCES);
308 }
309
310 lwkt_gettoken(&p->p_token);
311 kn->kn_ptr.p_proc = p;
312 kn->kn_flags |= EV_CLEAR; /* automatically set */
313
314 /*
315 * internal flag indicating registration done by kernel
316 */
317 if (kn->kn_flags & EV_FLAG1) {
318 kn->kn_data = kn->kn_sdata; /* ppid */
319 kn->kn_fflags = NOTE_CHILD;
320 kn->kn_flags &= ~EV_FLAG1;
321 }
322
323 knote_insert(&p->p_klist, kn);
324
325 /*
326 * Immediately activate any exit notes if the target process is a
327 * zombie. This is necessary to handle the case where the target
328 * process, e.g. a child, dies before the kevent is negistered.
329 */
330 if (immediate && filt_proc(kn, NOTE_EXIT))
331 KNOTE_ACTIVATE(kn);
332 lwkt_reltoken(&p->p_token);
333 PRELE(p);
334
335 return (0);
336 }
337
338 /*
339 * The knote may be attached to a different process, which may exit,
340 * leaving nothing for the knote to be attached to. So when the process
341 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
342 * it will be deleted when read out. However, as part of the knote deletion,
343 * this routine is called, so a check is needed to avoid actually performing
344 * a detach, because the original process does not exist any more.
345 */
346 static void
347 filt_procdetach(struct knote *kn)
348 {
349 struct proc *p;
350
351 if (kn->kn_status & KN_DETACHED)
352 return;
353 p = kn->kn_ptr.p_proc;
354 knote_remove(&p->p_klist, kn);
355 }
356
357 static int
358 filt_proc(struct knote *kn, long hint)
359 {
360 u_int event;
361
362 /*
363 * mask off extra data
364 */
365 event = (u_int)hint & NOTE_PCTRLMASK;
366
367 /*
368 * if the user is interested in this event, record it.
369 */
370 if (kn->kn_sfflags & event)
371 kn->kn_fflags |= event;
372
373 /*
374 * Process is gone, so flag the event as finished. Detach the
375 * knote from the process now because the process will be poof,
376 * gone later on.
377 */
378 if (event == NOTE_EXIT) {
379 struct proc *p = kn->kn_ptr.p_proc;
380 if ((kn->kn_status & KN_DETACHED) == 0) {
381 PHOLD(p);
382 knote_remove(&p->p_klist, kn);
383 kn->kn_status |= KN_DETACHED;
384 kn->kn_data = p->p_xstat;
385 kn->kn_ptr.p_proc = NULL;
386 PRELE(p);
387 }
388 kn->kn_flags |= (EV_EOF | EV_NODATA | EV_ONESHOT);
389 return (1);
390 }
391
392 /*
393 * process forked, and user wants to track the new process,
394 * so attach a new knote to it, and immediately report an
395 * event with the parent's pid.
396 */
397 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) {
398 struct kevent kev;
399 int error;
400 int n;
401
402 /*
403 * register knote with new process.
404 */
405 kev.ident = hint & NOTE_PDATAMASK; /* pid */
406 kev.filter = kn->kn_filter;
407 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
408 kev.fflags = kn->kn_sfflags;
409 kev.data = kn->kn_id; /* parent */
410 kev.udata = kn->kn_kevent.udata; /* preserve udata */
411 n = 1;
412 error = kqueue_register(kn->kn_kq, &kev, &n);
413 if (error)
414 kn->kn_fflags |= NOTE_TRACKERR;
415 }
416
417 return (kn->kn_fflags != 0);
418 }
419
420 static void
421 filt_timerreset(struct knote *kn)
422 {
423 struct callout *calloutp;
424 struct timeval tv;
425 int tticks;
426
427 tv.tv_sec = kn->kn_sdata / 1000;
428 tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
429 tticks = tvtohz_high(&tv);
430 calloutp = (struct callout *)kn->kn_hook;
431 callout_reset(calloutp, tticks, filt_timerexpire, kn);
432 }
433
434 /*
435 * The callout interlocks with callout_terminate() but can still
436 * race a deletion so if KN_DELETING is set we just don't touch
437 * the knote.
438 */
439 static void
440 filt_timerexpire(void *knx)
441 {
442 struct knote *kn = knx;
443 struct kqueue *kq = kn->kn_kq;
444
445 lwkt_getpooltoken(kq);
446
447 /*
448 * Open knote_acquire(), since we can't sleep in callout,
449 * however, we do need to record this expiration.
450 */
451 kn->kn_data++;
452 if (kn->kn_status & KN_PROCESSING) {
453 kn->kn_status |= KN_REPROCESS;
454 if ((kn->kn_status & KN_DELETING) == 0 &&
455 (kn->kn_flags & EV_ONESHOT) == 0)
456 filt_timerreset(kn);
457 lwkt_relpooltoken(kq);
458 return;
459 }
460 KASSERT((kn->kn_status & KN_DELETING) == 0,
461 ("acquire a deleting knote %#x", kn->kn_status));
462 kn->kn_status |= KN_PROCESSING;
463
464 KNOTE_ACTIVATE(kn);
465 if ((kn->kn_flags & EV_ONESHOT) == 0)
466 filt_timerreset(kn);
467
468 knote_release(kn);
469
470 lwkt_relpooltoken(kq);
471 }
472
473 /*
474 * data contains amount of time to sleep, in milliseconds
475 */
476 static int
477 filt_timerattach(struct knote *kn)
478 {
479 struct callout *calloutp;
480 int prev_ncallouts;
481
482 prev_ncallouts = atomic_fetchadd_int(&kq_ncallouts, 1);
483 if (prev_ncallouts >= kq_calloutmax) {
484 atomic_subtract_int(&kq_ncallouts, 1);
485 kn->kn_hook = NULL;
486 return (ENOMEM);
487 }
488
489 kn->kn_flags |= EV_CLEAR; /* automatically set */
490 calloutp = kmalloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
491 callout_init_mp(calloutp);
492 kn->kn_hook = (caddr_t)calloutp;
493
494 filt_timerreset(kn);
495 return (0);
496 }
497
498 /*
499 * This function is called with the knote flagged locked but it is
500 * still possible to race a callout event due to the callback blocking.
501 * We must call callout_terminate() instead of callout_stop() to deal
502 * with the race.
503 */
504 static void
505 filt_timerdetach(struct knote *kn)
506 {
507 struct callout *calloutp;
508
509 calloutp = (struct callout *)kn->kn_hook;
510 callout_terminate(calloutp);
511 kn->kn_hook = NULL;
512 kfree(calloutp, M_KQUEUE);
513 atomic_subtract_int(&kq_ncallouts, 1);
514 }
515
516 static int
517 filt_timer(struct knote *kn, long hint)
518 {
519 return (kn->kn_data != 0);
520 }
521
522 /*
523 * EVFILT_USER
524 */
525 static int
526 filt_userattach(struct knote *kn)
527 {
528 u_int ffctrl;
529
530 kn->kn_hook = NULL;
531 if (kn->kn_sfflags & NOTE_TRIGGER)
532 kn->kn_ptr.hookid = 1;
533 else
534 kn->kn_ptr.hookid = 0;
535
536 ffctrl = kn->kn_sfflags & NOTE_FFCTRLMASK;
537 kn->kn_sfflags &= NOTE_FFLAGSMASK;
538 switch (ffctrl) {
539 case NOTE_FFNOP:
540 break;
541
542 case NOTE_FFAND:
543 kn->kn_fflags &= kn->kn_sfflags;
544 break;
545
546 case NOTE_FFOR:
547 kn->kn_fflags |= kn->kn_sfflags;
548 break;
549
550 case NOTE_FFCOPY:
551 kn->kn_fflags = kn->kn_sfflags;
552 break;
553
554 default:
555 /* XXX Return error? */
556 break;
557 }
558 /* We just happen to copy this value as well. Undocumented. */
559 kn->kn_data = kn->kn_sdata;
560
561 return 0;
562 }
563
564 static void
565 filt_userdetach(struct knote *kn)
566 {
567 /* nothing to do */
568 }
569
570 static int
571 filt_user(struct knote *kn, long hint)
572 {
573 return (kn->kn_ptr.hookid);
574 }
575
576 static void
577 filt_usertouch(struct knote *kn, struct kevent *kev, u_long type)
578 {
579 u_int ffctrl;
580
581 switch (type) {
582 case EVENT_REGISTER:
583 if (kev->fflags & NOTE_TRIGGER)
584 kn->kn_ptr.hookid = 1;
585
586 ffctrl = kev->fflags & NOTE_FFCTRLMASK;
587 kev->fflags &= NOTE_FFLAGSMASK;
588 switch (ffctrl) {
589 case NOTE_FFNOP:
590 break;
591
592 case NOTE_FFAND:
593 kn->kn_fflags &= kev->fflags;
594 break;
595
596 case NOTE_FFOR:
597 kn->kn_fflags |= kev->fflags;
598 break;
599
600 case NOTE_FFCOPY:
601 kn->kn_fflags = kev->fflags;
602 break;
603
604 default:
605 /* XXX Return error? */
606 break;
607 }
608 /* We just happen to copy this value as well. Undocumented. */
609 kn->kn_data = kev->data;
610
611 /*
612 * This is not the correct use of EV_CLEAR in an event
613 * modification, it should have been passed as a NOTE instead.
614 * But we need to maintain compatibility with Apple & FreeBSD.
615 *
616 * Note however that EV_CLEAR can still be used when doing
617 * the initial registration of the event and works as expected
618 * (clears the event on reception).
619 */
620 if (kev->flags & EV_CLEAR) {
621 kn->kn_ptr.hookid = 0;
622 /*
623 * Clearing kn->kn_data is fine, since it gets set
624 * every time anyway. We just shouldn't clear
625 * kn->kn_fflags here, since that would limit the
626 * possible uses of this API. NOTE_FFAND or
627 * NOTE_FFCOPY should be used for explicitly clearing
628 * kn->kn_fflags.
629 */
630 kn->kn_data = 0;
631 }
632 break;
633
634 case EVENT_PROCESS:
635 *kev = kn->kn_kevent;
636 kev->fflags = kn->kn_fflags;
637 kev->data = kn->kn_data;
638 if (kn->kn_flags & EV_CLEAR) {
639 kn->kn_ptr.hookid = 0;
640 /* kn_data, kn_fflags handled by parent */
641 }
642 break;
643
644 default:
645 panic("filt_usertouch() - invalid type (%ld)", type);
646 break;
647 }
648 }
649
650 /*
651 * EVFILT_FS
652 */
653 struct klist fs_klist = SLIST_HEAD_INITIALIZER(&fs_klist);
654
655 static int
656 filt_fsattach(struct knote *kn)
657 {
658 kn->kn_flags |= EV_CLEAR;
659 knote_insert(&fs_klist, kn);
660
661 return (0);
662 }
663
664 static void
665 filt_fsdetach(struct knote *kn)
666 {
667 knote_remove(&fs_klist, kn);
668 }
669
670 static int
671 filt_fs(struct knote *kn, long hint)
672 {
673 kn->kn_fflags |= hint;
674 return (kn->kn_fflags != 0);
675 }
676
677 /*
678 * Initialize a kqueue.
679 *
680 * NOTE: The lwp/proc code initializes a kqueue for select/poll ops.
681 *
682 * MPSAFE
683 */
684 void
685 kqueue_init(struct kqueue *kq, struct filedesc *fdp)
686 {
687 TAILQ_INIT(&kq->kq_knpend);
688 TAILQ_INIT(&kq->kq_knlist);
689 kq->kq_count = 0;
690 kq->kq_fdp = fdp;
691 SLIST_INIT(&kq->kq_kqinfo.ki_note);
692 }
693
694 /*
695 * Terminate a kqueue. Freeing the actual kq itself is left up to the
696 * caller (it might be embedded in a lwp so we don't do it here).
697 *
698 * The kq's knlist must be completely eradicated so block on any
699 * processing races.
700 */
701 void
702 kqueue_terminate(struct kqueue *kq)
703 {
704 struct knote *kn;
705
706 lwkt_getpooltoken(kq);
707 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL) {
708 if (knote_acquire(kn))
709 knote_detach_and_drop(kn);
710 }
711 lwkt_relpooltoken(kq);
712
713 if (kq->kq_knhash) {
714 hashdestroy(kq->kq_knhash, M_KQUEUE, kq->kq_knhashmask);
715 kq->kq_knhash = NULL;
716 kq->kq_knhashmask = 0;
717 }
718 }
719
720 /*
721 * MPSAFE
722 */
723 int
724 sys_kqueue(struct kqueue_args *uap)
725 {
726 struct thread *td = curthread;
727 struct kqueue *kq;
728 struct file *fp;
729 int fd, error;
730
731 error = falloc(td->td_lwp, &fp, &fd);
732 if (error)
733 return (error);
734 fp->f_flag = FREAD | FWRITE;
735 fp->f_type = DTYPE_KQUEUE;
736 fp->f_ops = &kqueueops;
737
738 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO);
739 kqueue_init(kq, td->td_proc->p_fd);
740 fp->f_data = kq;
741
742 fsetfd(kq->kq_fdp, fp, fd);
743 uap->sysmsg_result = fd;
744 fdrop(fp);
745 return (error);
746 }
747
748 /*
749 * Copy 'count' items into the destination list pointed to by uap->eventlist.
750 */
751 static int
752 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res)
753 {
754 struct kevent_copyin_args *kap;
755 int error;
756
757 kap = (struct kevent_copyin_args *)arg;
758
759 error = copyout(kevp, kap->ka->eventlist, count * sizeof(*kevp));
760 if (error == 0) {
761 kap->ka->eventlist += count;
762 *res += count;
763 } else {
764 *res = -1;
765 }
766
767 return (error);
768 }
769
770 /*
771 * Copy at most 'max' items from the list pointed to by kap->changelist,
772 * return number of items in 'events'.
773 */
774 static int
775 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events)
776 {
777 struct kevent_copyin_args *kap;
778 int error, count;
779
780 kap = (struct kevent_copyin_args *)arg;
781
782 count = min(kap->ka->nchanges - kap->pchanges, max);
783 error = copyin(kap->ka->changelist, kevp, count * sizeof *kevp);
784 if (error == 0) {
785 kap->ka->changelist += count;
786 kap->pchanges += count;
787 *events = count;
788 }
789
790 return (error);
791 }
792
793 /*
794 * MPSAFE
795 */
796 int
797 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap,
798 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn,
799 struct timespec *tsp_in, int flags)
800 {
801 struct kevent *kevp;
802 struct timespec *tsp, ats;
803 int i, n, total, error, nerrors = 0;
804 int gobbled;
805 int lres;
806 int limit = kq_checkloop;
807 int closedcounter;
808 struct kevent kev[KQ_NEVENTS];
809 struct knote marker;
810 struct lwkt_token *tok;
811
812 if (tsp_in == NULL || tsp_in->tv_sec || tsp_in->tv_nsec)
813 atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC);
814
815 tsp = tsp_in;
816 *res = 0;
817
818 closedcounter = kq->kq_fdp->fd_closedcounter;
819
820 for (;;) {
821 n = 0;
822 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n);
823 if (error)
824 return error;
825 if (n == 0)
826 break;
827 for (i = 0; i < n; ++i)
828 kev[i].flags &= ~EV_SYSFLAGS;
829 for (i = 0; i < n; ++i) {
830 gobbled = n - i;
831 error = kqueue_register(kq, &kev[i], &gobbled);
832 i += gobbled - 1;
833 kevp = &kev[i];
834
835 /*
836 * If a registration returns an error we
837 * immediately post the error. The kevent()
838 * call itself will fail with the error if
839 * no space is available for posting.
840 *
841 * Such errors normally bypass the timeout/blocking
842 * code. However, if the copyoutfn function refuses
843 * to post the error (see sys_poll()), then we
844 * ignore it too.
845 */
846 if (error || (kevp->flags & EV_RECEIPT)) {
847 kevp->flags = EV_ERROR;
848 kevp->data = error;
849 lres = *res;
850 kevent_copyoutfn(uap, kevp, 1, res);
851 if (*res < 0) {
852 return error;
853 } else if (lres != *res) {
854 nevents--;
855 nerrors++;
856 }
857 }
858 }
859 }
860 if (nerrors)
861 return 0;
862
863 /*
864 * Acquire/wait for events - setup timeout
865 */
866 if (tsp != NULL) {
867 if (tsp->tv_sec || tsp->tv_nsec) {
868 getnanouptime(&ats);
869 timespecadd(tsp, &ats); /* tsp = target time */
870 }
871 }
872
873 /*
874 * Loop as required.
875 *
876 * Collect as many events as we can. Sleeping on successive
877 * loops is disabled if copyoutfn has incremented (*res).
878 *
879 * The loop stops if an error occurs, all events have been
880 * scanned (the marker has been reached), or fewer than the
881 * maximum number of events is found.
882 *
883 * The copyoutfn function does not have to increment (*res) in
884 * order for the loop to continue.
885 *
886 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents.
887 */
888 total = 0;
889 error = 0;
890 marker.kn_filter = EVFILT_MARKER;
891 marker.kn_status = KN_PROCESSING;
892 tok = lwkt_token_pool_lookup(kq);
893 lwkt_gettoken(tok);
894 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
895 lwkt_reltoken(tok);
896 while ((n = nevents - total) > 0) {
897 if (n > KQ_NEVENTS)
898 n = KQ_NEVENTS;
899
900 /*
901 * If no events are pending sleep until timeout (if any)
902 * or an event occurs.
903 *
904 * After the sleep completes the marker is moved to the
905 * end of the list, making any received events available
906 * to our scan.
907 */
908 if (kq->kq_count == 0 && *res == 0) {
909 int timeout, ustimeout = 0;
910
911 if (tsp == NULL) {
912 timeout = 0;
913 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) {
914 error = EWOULDBLOCK;
915 break;
916 } else {
917 struct timespec atx = *tsp;
918
919 getnanouptime(&ats);
920 timespecsub(&atx, &ats);
921 if (atx.tv_sec < 0) {
922 error = EWOULDBLOCK;
923 break;
924 } else {
925 timeout = atx.tv_sec > 24 * 60 * 60 ?
926 24 * 60 * 60 * hz :
927 tstohz_high(&atx);
928 }
929 if (flags & KEVENT_TIMEOUT_PRECISE &&
930 timeout != 0) {
931 if (atx.tv_sec == 0 &&
932 atx.tv_nsec < kq_sleep_threshold) {
933 DELAY(atx.tv_nsec / 1000);
934 error = EWOULDBLOCK;
935 break;
936 } else if (atx.tv_sec < 2000) {
937 ustimeout = atx.tv_sec *
938 1000000 + atx.tv_nsec/1000;
939 } else {
940 ustimeout = 2000000000;
941 }
942 }
943 }
944
945 lwkt_gettoken(tok);
946 if (kq->kq_count == 0) {
947 kq->kq_sleep_cnt++;
948 if (__predict_false(kq->kq_sleep_cnt == 0)) {
949 /*
950 * Guard against possible wrapping. And
951 * set it to 2, so that kqueue_wakeup()
952 * can wake everyone up.
953 */
954 kq->kq_sleep_cnt = 2;
955 }
956 if ((flags & KEVENT_TIMEOUT_PRECISE) &&
957 timeout != 0) {
958 error = precise_sleep(kq, PCATCH,
959 "kqread", ustimeout);
960 } else {
961 error = tsleep(kq, PCATCH, "kqread",
962 timeout);
963 }
964
965 /* don't restart after signals... */
966 if (error == ERESTART)
967 error = EINTR;
968 if (error) {
969 lwkt_reltoken(tok);
970 break;
971 }
972
973 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
974 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker,
975 kn_tqe);
976 }
977 lwkt_reltoken(tok);
978 }
979
980 /*
981 * Process all received events
982 * Account for all non-spurious events in our total
983 */
984 i = kqueue_scan(kq, kev, n, &marker, closedcounter);
985 if (i) {
986 lres = *res;
987 error = kevent_copyoutfn(uap, kev, i, res);
988 total += *res - lres;
989 if (error)
990 break;
991 }
992 if (limit && --limit == 0)
993 panic("kqueue: checkloop failed i=%d", i);
994
995 /*
996 * Normally when fewer events are returned than requested
997 * we can stop. However, if only spurious events were
998 * collected the copyout will not bump (*res) and we have
999 * to continue.
1000 */
1001 if (i < n && *res)
1002 break;
1003
1004 /*
1005 * Deal with an edge case where spurious events can cause
1006 * a loop to occur without moving the marker. This can
1007 * prevent kqueue_scan() from picking up new events which
1008 * race us. We must be sure to move the marker for this
1009 * case.
1010 *
1011 * NOTE: We do not want to move the marker if events
1012 * were scanned because normal kqueue operations
1013 * may reactivate events. Moving the marker in
1014 * that case could result in duplicates for the
1015 * same event.
1016 */
1017 if (i == 0) {
1018 lwkt_gettoken(tok);
1019 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
1020 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
1021 lwkt_reltoken(tok);
1022 }
1023 }
1024 lwkt_gettoken(tok);
1025 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
1026 lwkt_reltoken(tok);
1027
1028 /* Timeouts do not return EWOULDBLOCK. */
1029 if (error == EWOULDBLOCK)
1030 error = 0;
1031 return error;
1032 }
1033
1034 /*
1035 * MPALMOSTSAFE
1036 */
1037 int
1038 sys_kevent(struct kevent_args *uap)
1039 {
1040 struct thread *td = curthread;
1041 struct timespec ts, *tsp;
1042 struct kqueue *kq;
1043 struct file *fp = NULL;
1044 struct kevent_copyin_args *kap, ka;
1045 int error;
1046
1047 if (uap->timeout) {
1048 error = copyin(uap->timeout, &ts, sizeof(ts));
1049 if (error)
1050 return (error);
1051 tsp = &ts;
1052 } else {
1053 tsp = NULL;
1054 }
1055 fp = holdfp(td, uap->fd, -1);
1056 if (fp == NULL)
1057 return (EBADF);
1058 if (fp->f_type != DTYPE_KQUEUE) {
1059 fdrop(fp);
1060 return (EBADF);
1061 }
1062
1063 kq = (struct kqueue *)fp->f_data;
1064
1065 kap = &ka;
1066 kap->ka = uap;
1067 kap->pchanges = 0;
1068
1069 error = kern_kevent(kq, uap->nevents, &uap->sysmsg_result, kap,
1070 kevent_copyin, kevent_copyout, tsp, 0);
1071
1072 dropfp(td, uap->fd, fp);
1073
1074 return (error);
1075 }
1076
1077 /*
1078 * Efficiently load multiple file pointers. This significantly reduces
1079 * threaded overhead. When doing simple polling we can depend on the
1080 * per-thread (fd,fp) cache. With more descriptors, we batch.
1081 */
1082 static
1083 void
1084 floadkevfps(thread_t td, struct filedesc *fdp, struct kevent *kev,
1085 struct file **fp, int climit)
1086 {
1087 struct filterops *fops;
1088 int tdcache;
1089
1090 if (climit <= 2 && td->td_proc && td->td_proc->p_fd == fdp) {
1091 tdcache = 1;
1092 } else {
1093 tdcache = 0;
1094 spin_lock_shared(&fdp->fd_spin);
1095 }
1096
1097 while (climit) {
1098 *fp = NULL;
1099 if (kev->filter < 0 &&
1100 kev->filter + EVFILT_SYSCOUNT >= 0) {
1101 fops = sysfilt_ops[~kev->filter];
1102 if (fops->f_flags & FILTEROP_ISFD) {
1103 if (tdcache) {
1104 *fp = holdfp(td, kev->ident, -1);
1105 } else {
1106 *fp = holdfp_fdp_locked(fdp,
1107 kev->ident, -1);
1108 }
1109 }
1110 }
1111 --climit;
1112 ++fp;
1113 ++kev;
1114 }
1115 if (tdcache == 0)
1116 spin_unlock_shared(&fdp->fd_spin);
1117 }
1118
1119 /*
1120 * Register up to *countp kev's. Always registers at least 1.
1121 *
1122 * The number registered is returned in *countp.
1123 *
1124 * If an error occurs or a kev is flagged EV_RECEIPT, it is
1125 * processed and included in *countp, and processing then
1126 * stops.
1127 */
1128 int
1129 kqueue_register(struct kqueue *kq, struct kevent *kev, int *countp)
1130 {
1131 struct filedesc *fdp = kq->kq_fdp;
1132 struct klist *list = NULL;
1133 struct filterops *fops;
1134 struct file *fp[KQ_NEVENTS];
1135 struct knote *kn = NULL;
1136 struct thread *td;
1137 int error;
1138 int count;
1139 int climit;
1140 int closedcounter;
1141 struct knote_cache_list *cache_list;
1142
1143 td = curthread;
1144 climit = *countp;
1145 if (climit > KQ_NEVENTS)
1146 climit = KQ_NEVENTS;
1147 closedcounter = fdp->fd_closedcounter;
1148 floadkevfps(td, fdp, kev, fp, climit);
1149
1150 lwkt_getpooltoken(kq);
1151 count = 0;
1152
1153 /*
1154 * To avoid races, only one thread can register events on this
1155 * kqueue at a time.
1156 */
1157 while (__predict_false(kq->kq_regtd != NULL && kq->kq_regtd != td)) {
1158 kq->kq_state |= KQ_REGWAIT;
1159 tsleep(&kq->kq_regtd, 0, "kqreg", 0);
1160 }
1161 if (__predict_false(kq->kq_regtd != NULL)) {
1162 /* Recursive calling of kqueue_register() */
1163 td = NULL;
1164 } else {
1165 /* Owner of the kq_regtd, i.e. td != NULL */
1166 kq->kq_regtd = td;
1167 }
1168
1169 loop:
1170 if (kev->filter < 0) {
1171 if (kev->filter + EVFILT_SYSCOUNT < 0) {
1172 error = EINVAL;
1173 ++count;
1174 goto done;
1175 }
1176 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */
1177 } else {
1178 /*
1179 * XXX
1180 * filter attach routine is responsible for insuring that
1181 * the identifier can be attached to it.
1182 */
1183 error = EINVAL;
1184 ++count;
1185 goto done;
1186 }
1187
1188 if (fops->f_flags & FILTEROP_ISFD) {
1189 /* validate descriptor */
1190 if (fp[count] == NULL) {
1191 error = EBADF;
1192 ++count;
1193 goto done;
1194 }
1195 }
1196
1197 cache_list = &knote_cache_lists[mycpuid];
1198 if (SLIST_EMPTY(&cache_list->knote_cache)) {
1199 struct knote *new_kn;
1200
1201 new_kn = knote_alloc();
1202 crit_enter();
1203 SLIST_INSERT_HEAD(&cache_list->knote_cache, new_kn, kn_link);
1204 cache_list->knote_cache_cnt++;
1205 crit_exit();
1206 }
1207
1208 if (fp[count] != NULL) {
1209 list = &fp[count]->f_klist;
1210 } else if (kq->kq_knhashmask) {
1211 list = &kq->kq_knhash[
1212 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
1213 }
1214 if (list != NULL) {
1215 lwkt_getpooltoken(list);
1216 again:
1217 SLIST_FOREACH(kn, list, kn_link) {
1218 if (kn->kn_kq == kq &&
1219 kn->kn_filter == kev->filter &&
1220 kn->kn_id == kev->ident) {
1221 if (knote_acquire(kn) == 0)
1222 goto again;
1223 break;
1224 }
1225 }
1226 lwkt_relpooltoken(list);
1227 }
1228
1229 /*
1230 * NOTE: At this point if kn is non-NULL we will have acquired
1231 * it and set KN_PROCESSING.
1232 */
1233 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) {
1234 error = ENOENT;
1235 ++count;
1236 goto done;
1237 }
1238
1239 /*
1240 * kn now contains the matching knote, or NULL if no match
1241 */
1242 if (kev->flags & EV_ADD) {
1243 if (kn == NULL) {
1244 crit_enter();
1245 kn = SLIST_FIRST(&cache_list->knote_cache);
1246 if (kn == NULL) {
1247 crit_exit();
1248 kn = knote_alloc();
1249 } else {
1250 SLIST_REMOVE_HEAD(&cache_list->knote_cache,
1251 kn_link);
1252 cache_list->knote_cache_cnt--;
1253 crit_exit();
1254 }
1255 kn->kn_fp = fp[count];
1256 kn->kn_kq = kq;
1257 kn->kn_fop = fops;
1258
1259 /*
1260 * apply reference count to knote structure, and
1261 * do not release it at the end of this routine.
1262 */
1263 fp[count] = NULL; /* safety */
1264
1265 kn->kn_sfflags = kev->fflags;
1266 kn->kn_sdata = kev->data;
1267 kev->fflags = 0;
1268 kev->data = 0;
1269 kn->kn_kevent = *kev;
1270
1271 /*
1272 * KN_PROCESSING prevents the knote from getting
1273 * ripped out from under us while we are trying
1274 * to attach it, in case the attach blocks.
1275 */
1276 kn->kn_status = KN_PROCESSING;
1277 knote_attach(kn);
1278 if ((error = filter_attach(kn)) != 0) {
1279 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1280 knote_drop(kn);
1281 ++count;
1282 goto done;
1283 }
1284
1285 /*
1286 * Interlock against close races which either tried
1287 * to remove our knote while we were blocked or missed
1288 * it entirely prior to our attachment. We do not
1289 * want to end up with a knote on a closed descriptor.
1290 */
1291 if ((fops->f_flags & FILTEROP_ISFD) &&
1292 checkfdclosed(curthread, fdp, kev->ident, kn->kn_fp,
1293 closedcounter)) {
1294 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1295 }
1296 } else {
1297 /*
1298 * The user may change some filter values after the
1299 * initial EV_ADD, but doing so will not reset any
1300 * filter which have already been triggered.
1301 */
1302 KKASSERT(kn->kn_status & KN_PROCESSING);
1303 if (fops == &user_filtops) {
1304 filt_usertouch(kn, kev, EVENT_REGISTER);
1305 } else {
1306 kn->kn_sfflags = kev->fflags;
1307 kn->kn_sdata = kev->data;
1308 kn->kn_kevent.udata = kev->udata;
1309 }
1310 }
1311
1312 /*
1313 * Execute the filter event to immediately activate the
1314 * knote if necessary. If reprocessing events are pending
1315 * due to blocking above we do not run the filter here
1316 * but instead let knote_release() do it. Otherwise we
1317 * might run the filter on a deleted event.
1318 */
1319 if ((kn->kn_status & KN_REPROCESS) == 0) {
1320 if (filter_event(kn, 0))
1321 KNOTE_ACTIVATE(kn);
1322 }
1323 } else if (kev->flags & EV_DELETE) {
1324 /*
1325 * Delete the existing knote
1326 */
1327 knote_detach_and_drop(kn);
1328 error = 0;
1329 ++count;
1330 goto done;
1331 } else {
1332 /*
1333 * Modify an existing event.
1334 *
1335 * The user may change some filter values after the
1336 * initial EV_ADD, but doing so will not reset any
1337 * filter which have already been triggered.
1338 */
1339 KKASSERT(kn->kn_status & KN_PROCESSING);
1340 if (fops == &user_filtops) {
1341 filt_usertouch(kn, kev, EVENT_REGISTER);
1342 } else {
1343 kn->kn_sfflags = kev->fflags;
1344 kn->kn_sdata = kev->data;
1345 kn->kn_kevent.udata = kev->udata;
1346 }
1347
1348 /*
1349 * Execute the filter event to immediately activate the
1350 * knote if necessary. If reprocessing events are pending
1351 * due to blocking above we do not run the filter here
1352 * but instead let knote_release() do it. Otherwise we
1353 * might run the filter on a deleted event.
1354 */
1355 if ((kn->kn_status & KN_REPROCESS) == 0) {
1356 if (filter_event(kn, 0))
1357 KNOTE_ACTIVATE(kn);
1358 }
1359 }
1360
1361 /*
1362 * Disablement does not deactivate a knote here.
1363 */
1364 if ((kev->flags & EV_DISABLE) &&
1365 ((kn->kn_status & KN_DISABLED) == 0)) {
1366 kn->kn_status |= KN_DISABLED;
1367 }
1368
1369 /*
1370 * Re-enablement may have to immediately enqueue an active knote.
1371 */
1372 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
1373 kn->kn_status &= ~KN_DISABLED;
1374 if ((kn->kn_status & KN_ACTIVE) &&
1375 ((kn->kn_status & KN_QUEUED) == 0)) {
1376 knote_enqueue(kn);
1377 }
1378 }
1379
1380 /*
1381 * Handle any required reprocessing
1382 */
1383 knote_release(kn);
1384 /* kn may be invalid now */
1385
1386 /*
1387 * Loop control. We stop on errors (above), and also stop after
1388 * processing EV_RECEIPT, so the caller can process it.
1389 */
1390 ++count;
1391 if (kev->flags & EV_RECEIPT) {
1392 error = 0;
1393 goto done;
1394 }
1395 ++kev;
1396 if (count < climit) {
1397 if (fp[count-1]) /* drop unprocessed fp */
1398 fdrop(fp[count-1]);
1399 goto loop;
1400 }
1401
1402 /*
1403 * Cleanup
1404 */
1405 done:
1406 if (td != NULL) { /* Owner of the kq_regtd */
1407 kq->kq_regtd = NULL;
1408 if (__predict_false(kq->kq_state & KQ_REGWAIT)) {
1409 kq->kq_state &= ~KQ_REGWAIT;
1410 wakeup(&kq->kq_regtd);
1411 }
1412 }
1413 lwkt_relpooltoken(kq);
1414
1415 /*
1416 * Drop unprocessed file pointers
1417 */
1418 *countp = count;
1419 if (count && fp[count-1])
1420 fdrop(fp[count-1]);
1421 while (count < climit) {
1422 if (fp[count])
1423 fdrop(fp[count]);
1424 ++count;
1425 }
1426 return (error);
1427 }
1428
1429 /*
1430 * Scan the kqueue, return the number of active events placed in kevp up
1431 * to count.
1432 *
1433 * Continuous mode events may get recycled, do not continue scanning past
1434 * marker unless no events have been collected.
1435 */
1436 static int
1437 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
1438 struct knote *marker, int closedcounter)
1439 {
1440 struct knote *kn, local_marker;
1441 thread_t td = curthread;
1442 int total;
1443
1444 total = 0;
1445 local_marker.kn_filter = EVFILT_MARKER;
1446 local_marker.kn_status = KN_PROCESSING;
1447
1448 lwkt_getpooltoken(kq);
1449
1450 /*
1451 * Collect events.
1452 */
1453 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe);
1454 while (count) {
1455 kn = TAILQ_NEXT(&local_marker, kn_tqe);
1456 if (kn->kn_filter == EVFILT_MARKER) {
1457 /* Marker reached, we are done */
1458 if (kn == marker)
1459 break;
1460
1461 /* Move local marker past some other threads marker */
1462 kn = TAILQ_NEXT(kn, kn_tqe);
1463 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1464 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe);
1465 continue;
1466 }
1467
1468 /*
1469 * We can't skip a knote undergoing processing, otherwise
1470 * we risk not returning it when the user process expects
1471 * it should be returned. Sleep and retry.
1472 */
1473 if (knote_acquire(kn) == 0)
1474 continue;
1475
1476 /*
1477 * Remove the event for processing.
1478 *
1479 * WARNING! We must leave KN_QUEUED set to prevent the
1480 * event from being KNOTE_ACTIVATE()d while
1481 * the queue state is in limbo, in case we
1482 * block.
1483 */
1484 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
1485 kq->kq_count--;
1486
1487 /*
1488 * We have to deal with an extremely important race against
1489 * file descriptor close()s here. The file descriptor can
1490 * disappear MPSAFE, and there is a small window of
1491 * opportunity between that and the call to knote_fdclose().
1492 *
1493 * If we hit that window here while doselect or dopoll is
1494 * trying to delete a spurious event they will not be able
1495 * to match up the event against a knote and will go haywire.
1496 */
1497 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) &&
1498 checkfdclosed(td, kq->kq_fdp, kn->kn_kevent.ident,
1499 kn->kn_fp, closedcounter)) {
1500 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1501 }
1502
1503 if (kn->kn_status & KN_DISABLED) {
1504 /*
1505 * If disabled we ensure the event is not queued
1506 * but leave its active bit set. On re-enablement
1507 * the event may be immediately triggered.
1508 */
1509 kn->kn_status &= ~KN_QUEUED;
1510 } else if ((kn->kn_flags & EV_ONESHOT) == 0 &&
1511 (kn->kn_status & KN_DELETING) == 0 &&
1512 filter_event(kn, 0) == 0) {
1513 /*
1514 * If not running in one-shot mode and the event
1515 * is no longer present we ensure it is removed
1516 * from the queue and ignore it.
1517 */
1518 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
1519 } else {
1520 /*
1521 * Post the event
1522 */
1523 if (kn->kn_fop == &user_filtops)
1524 filt_usertouch(kn, kevp, EVENT_PROCESS);
1525 else
1526 *kevp = kn->kn_kevent;
1527 ++kevp;
1528 ++total;
1529 --count;
1530
1531 if (kn->kn_flags & EV_ONESHOT) {
1532 kn->kn_status &= ~KN_QUEUED;
1533 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1534 } else {
1535 if (kn->kn_flags & (EV_CLEAR | EV_DISPATCH)) {
1536 if (kn->kn_flags & EV_CLEAR) {
1537 kn->kn_data = 0;
1538 kn->kn_fflags = 0;
1539 }
1540 if (kn->kn_flags & EV_DISPATCH) {
1541 kn->kn_status |= KN_DISABLED;
1542 }
1543 kn->kn_status &= ~(KN_QUEUED |
1544 KN_ACTIVE);
1545 } else {
1546 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1547 kq->kq_count++;
1548 }
1549 }
1550 }
1551
1552 /*
1553 * Handle any post-processing states
1554 */
1555 knote_release(kn);
1556 }
1557 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1558
1559 lwkt_relpooltoken(kq);
1560 return (total);
1561 }
1562
1563 /*
1564 * XXX
1565 * This could be expanded to call kqueue_scan, if desired.
1566 *
1567 * MPSAFE
1568 */
1569 static int
1570 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1571 {
1572 return (ENXIO);
1573 }
1574
1575 /*
1576 * MPSAFE
1577 */
1578 static int
1579 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1580 {
1581 return (ENXIO);
1582 }
1583
1584 /*
1585 * MPALMOSTSAFE
1586 */
1587 static int
1588 kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
1589 struct ucred *cred, struct sysmsg *msg)
1590 {
1591 struct kqueue *kq;
1592 int error;
1593
1594 kq = (struct kqueue *)fp->f_data;
1595 lwkt_getpooltoken(kq);
1596 switch(com) {
1597 case FIOASYNC:
1598 if (*(int *)data)
1599 kq->kq_state |= KQ_ASYNC;
1600 else
1601 kq->kq_state &= ~KQ_ASYNC;
1602 error = 0;
1603 break;
1604 case FIOSETOWN:
1605 error = fsetown(*(int *)data, &kq->kq_sigio);
1606 break;
1607 default:
1608 error = ENOTTY;
1609 break;
1610 }
1611 lwkt_relpooltoken(kq);
1612 return (error);
1613 }
1614
1615 /*
1616 * MPSAFE
1617 */
1618 static int
1619 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred)
1620 {
1621 struct kqueue *kq = (struct kqueue *)fp->f_data;
1622
1623 bzero((void *)st, sizeof(*st));
1624 st->st_size = kq->kq_count;
1625 st->st_blksize = sizeof(struct kevent);
1626 st->st_mode = S_IFIFO;
1627 return (0);
1628 }
1629
1630 /*
1631 * MPSAFE
1632 */
1633 static int
1634 kqueue_close(struct file *fp)
1635 {
1636 struct kqueue *kq = (struct kqueue *)fp->f_data;
1637
1638 kqueue_terminate(kq);
1639
1640 fp->f_data = NULL;
1641 funsetown(&kq->kq_sigio);
1642
1643 kfree(kq, M_KQUEUE);
1644 return (0);
1645 }
1646
1647 static void
1648 kqueue_wakeup(struct kqueue *kq)
1649 {
1650 if (kq->kq_sleep_cnt) {
1651 u_int sleep_cnt = kq->kq_sleep_cnt;
1652
1653 kq->kq_sleep_cnt = 0;
1654 if (sleep_cnt == 1)
1655 wakeup_one(kq);
1656 else
1657 wakeup(kq);
1658 }
1659 KNOTE(&kq->kq_kqinfo.ki_note, 0);
1660 }
1661
1662 /*
1663 * Calls filterops f_attach function, acquiring mplock if filter is not
1664 * marked as FILTEROP_MPSAFE.
1665 *
1666 * Caller must be holding the related kq token
1667 */
1668 static int
1669 filter_attach(struct knote *kn)
1670 {
1671 int ret;
1672
1673 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1674 ret = kn->kn_fop->f_attach(kn);
1675 } else {
1676 get_mplock();
1677 ret = kn->kn_fop->f_attach(kn);
1678 rel_mplock();
1679 }
1680 return (ret);
1681 }
1682
1683 /*
1684 * Detach the knote and drop it, destroying the knote.
1685 *
1686 * Calls filterops f_detach function, acquiring mplock if filter is not
1687 * marked as FILTEROP_MPSAFE.
1688 *
1689 * Caller must be holding the related kq token
1690 */
1691 static void
1692 knote_detach_and_drop(struct knote *kn)
1693 {
1694 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1695 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1696 kn->kn_fop->f_detach(kn);
1697 } else {
1698 get_mplock();
1699 kn->kn_fop->f_detach(kn);
1700 rel_mplock();
1701 }
1702 knote_drop(kn);
1703 }
1704
1705 /*
1706 * Calls filterops f_event function, acquiring mplock if filter is not
1707 * marked as FILTEROP_MPSAFE.
1708 *
1709 * If the knote is in the middle of being created or deleted we cannot
1710 * safely call the filter op.
1711 *
1712 * Caller must be holding the related kq token
1713 */
1714 static int
1715 filter_event(struct knote *kn, long hint)
1716 {
1717 int ret;
1718
1719 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1720 ret = kn->kn_fop->f_event(kn, hint);
1721 } else {
1722 get_mplock();
1723 ret = kn->kn_fop->f_event(kn, hint);
1724 rel_mplock();
1725 }
1726 return (ret);
1727 }
1728
1729 /*
1730 * Walk down a list of knotes, activating them if their event has triggered.
1731 *
1732 * If we encounter any knotes which are undergoing processing we just mark
1733 * them for reprocessing and do not try to [re]activate the knote. However,
1734 * if a hint is being passed we have to wait and that makes things a bit
1735 * sticky.
1736 */
1737 void
1738 knote(struct klist *list, long hint)
1739 {
1740 struct kqueue *kq;
1741 struct knote *kn;
1742 struct knote *kntmp;
1743
1744 lwkt_getpooltoken(list);
1745 restart:
1746 SLIST_FOREACH(kn, list, kn_next) {
1747 kq = kn->kn_kq;
1748 lwkt_getpooltoken(kq);
1749
1750 /* temporary verification hack */
1751 SLIST_FOREACH(kntmp, list, kn_next) {
1752 if (kn == kntmp)
1753 break;
1754 }
1755 if (kn != kntmp || kn->kn_kq != kq) {
1756 lwkt_relpooltoken(kq);
1757 goto restart;
1758 }
1759
1760 if (kn->kn_status & KN_PROCESSING) {
1761 /*
1762 * Someone else is processing the knote, ask the
1763 * other thread to reprocess it and don't mess
1764 * with it otherwise.
1765 */
1766 if (hint == 0) {
1767 kn->kn_status |= KN_REPROCESS;
1768 lwkt_relpooltoken(kq);
1769 continue;
1770 }
1771
1772 /*
1773 * If the hint is non-zero we have to wait or risk
1774 * losing the state the caller is trying to update.
1775 *
1776 * XXX This is a real problem, certain process
1777 * and signal filters will bump kn_data for
1778 * already-processed notes more than once if
1779 * we restart the list scan. FIXME.
1780 */
1781 kn->kn_status |= KN_WAITING | KN_REPROCESS;
1782 tsleep(kn, 0, "knotec", hz);
1783 lwkt_relpooltoken(kq);
1784 goto restart;
1785 }
1786
1787 /*
1788 * Become the reprocessing master ourselves.
1789 *
1790 * If hint is non-zero running the event is mandatory
1791 * when not deleting so do it whether reprocessing is
1792 * set or not.
1793 */
1794 kn->kn_status |= KN_PROCESSING;
1795 if ((kn->kn_status & KN_DELETING) == 0) {
1796 if (filter_event(kn, hint))
1797 KNOTE_ACTIVATE(kn);
1798 }
1799 if (knote_release(kn)) {
1800 lwkt_relpooltoken(kq);
1801 goto restart;
1802 }
1803 lwkt_relpooltoken(kq);
1804 }
1805 lwkt_relpooltoken(list);
1806 }
1807
1808 /*
1809 * Insert knote at head of klist.
1810 *
1811 * This function may only be called via a filter function and thus
1812 * kq_token should already be held and marked for processing.
1813 */
1814 void
1815 knote_insert(struct klist *klist, struct knote *kn)
1816 {
1817 lwkt_getpooltoken(klist);
1818 KKASSERT(kn->kn_status & KN_PROCESSING);
1819 SLIST_INSERT_HEAD(klist, kn, kn_next);
1820 lwkt_relpooltoken(klist);
1821 }
1822
1823 /*
1824 * Remove knote from a klist
1825 *
1826 * This function may only be called via a filter function and thus
1827 * kq_token should already be held and marked for processing.
1828 */
1829 void
1830 knote_remove(struct klist *klist, struct knote *kn)
1831 {
1832 lwkt_getpooltoken(klist);
1833 KKASSERT(kn->kn_status & KN_PROCESSING);
1834 SLIST_REMOVE(klist, kn, knote, kn_next);
1835 lwkt_relpooltoken(klist);
1836 }
1837
1838 void
1839 knote_assume_knotes(struct kqinfo *src, struct kqinfo *dst,
1840 struct filterops *ops, void *hook)
1841 {
1842 struct kqueue *kq;
1843 struct knote *kn;
1844
1845 lwkt_getpooltoken(&src->ki_note);
1846 lwkt_getpooltoken(&dst->ki_note);
1847 while ((kn = SLIST_FIRST(&src->ki_note)) != NULL) {
1848 kq = kn->kn_kq;
1849 lwkt_getpooltoken(kq);
1850 if (SLIST_FIRST(&src->ki_note) != kn || kn->kn_kq != kq) {
1851 lwkt_relpooltoken(kq);
1852 continue;
1853 }
1854 if (knote_acquire(kn)) {
1855 knote_remove(&src->ki_note, kn);
1856 kn->kn_fop = ops;
1857 kn->kn_hook = hook;
1858 knote_insert(&dst->ki_note, kn);
1859 knote_release(kn);
1860 /* kn may be invalid now */
1861 }
1862 lwkt_relpooltoken(kq);
1863 }
1864 lwkt_relpooltoken(&dst->ki_note);
1865 lwkt_relpooltoken(&src->ki_note);
1866 }
1867
1868 /*
1869 * Remove all knotes referencing a specified fd
1870 */
1871 void
1872 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd)
1873 {
1874 struct kqueue *kq;
1875 struct knote *kn;
1876 struct knote *kntmp;
1877
1878 lwkt_getpooltoken(&fp->f_klist);
1879 restart:
1880 SLIST_FOREACH(kn, &fp->f_klist, kn_link) {
1881 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) {
1882 kq = kn->kn_kq;
1883 lwkt_getpooltoken(kq);
1884
1885 /* temporary verification hack */
1886 SLIST_FOREACH(kntmp, &fp->f_klist, kn_link) {
1887 if (kn == kntmp)
1888 break;
1889 }
1890 if (kn != kntmp || kn->kn_kq->kq_fdp != fdp ||
1891 kn->kn_id != fd || kn->kn_kq != kq) {
1892 lwkt_relpooltoken(kq);
1893 goto restart;
1894 }
1895 if (knote_acquire(kn))
1896 knote_detach_and_drop(kn);
1897 lwkt_relpooltoken(kq);
1898 goto restart;
1899 }
1900 }
1901 lwkt_relpooltoken(&fp->f_klist);
1902 }
1903
1904 /*
1905 * Low level attach function.
1906 *
1907 * The knote should already be marked for processing.
1908 * Caller must hold the related kq token.
1909 */
1910 static void
1911 knote_attach(struct knote *kn)
1912 {
1913 struct klist *list;
1914 struct kqueue *kq = kn->kn_kq;
1915
1916 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1917 KKASSERT(kn->kn_fp);
1918 list = &kn->kn_fp->f_klist;
1919 } else {
1920 if (kq->kq_knhashmask == 0)
1921 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
1922 &kq->kq_knhashmask);
1923 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1924 }
1925 lwkt_getpooltoken(list);
1926 SLIST_INSERT_HEAD(list, kn, kn_link);
1927 lwkt_relpooltoken(list);
1928 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink);
1929 }
1930
1931 /*
1932 * Low level drop function.
1933 *
1934 * The knote should already be marked for processing.
1935 * Caller must hold the related kq token.
1936 */
1937 static void
1938 knote_drop(struct knote *kn)
1939 {
1940 struct kqueue *kq;
1941 struct klist *list;
1942
1943 kq = kn->kn_kq;
1944
1945 if (kn->kn_fop->f_flags & FILTEROP_ISFD)
1946 list = &kn->kn_fp->f_klist;
1947 else
1948 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1949
1950 lwkt_getpooltoken(list);
1951 SLIST_REMOVE(list, kn, knote, kn_link);
1952 lwkt_relpooltoken(list);
1953 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink);
1954 if (kn->kn_status & KN_QUEUED)
1955 knote_dequeue(kn);
1956 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1957 fdrop(kn->kn_fp);
1958 kn->kn_fp = NULL;
1959 }
1960 knote_free(kn);
1961 }
1962
1963 /*
1964 * Low level enqueue function.
1965 *
1966 * The knote should already be marked for processing.
1967 * Caller must be holding the kq token
1968 */
1969 static void
1970 knote_enqueue(struct knote *kn)
1971 {
1972 struct kqueue *kq = kn->kn_kq;
1973
1974 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
1975 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1976 kn->kn_status |= KN_QUEUED;
1977 ++kq->kq_count;
1978
1979 /*
1980 * Send SIGIO on request (typically set up as a mailbox signal)
1981 */
1982 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1)
1983 pgsigio(kq->kq_sigio, SIGIO, 0);
1984
1985 kqueue_wakeup(kq);
1986 }
1987
1988 /*
1989 * Low level dequeue function.
1990 *
1991 * The knote should already be marked for processing.
1992 * Caller must be holding the kq token
1993 */
1994 static void
1995 knote_dequeue(struct knote *kn)
1996 {
1997 struct kqueue *kq = kn->kn_kq;
1998
1999 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
2000 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
2001 kn->kn_status &= ~KN_QUEUED;
2002 kq->kq_count--;
2003 }
2004
2005 static struct knote *
2006 knote_alloc(void)
2007 {
2008 return kmalloc(sizeof(struct knote), M_KQUEUE, M_WAITOK);
2009 }
2010
2011 static void
2012 knote_free(struct knote *kn)
2013 {
2014 struct knote_cache_list *cache_list;
2015
2016 cache_list = &knote_cache_lists[mycpuid];
2017 if (cache_list->knote_cache_cnt < KNOTE_CACHE_MAX) {
2018 crit_enter();
2019 SLIST_INSERT_HEAD(&cache_list->knote_cache, kn, kn_link);
2020 cache_list->knote_cache_cnt++;
2021 crit_exit();
2022 return;
2023 }
2024 kfree(kn, M_KQUEUE);
2025 }
2026
2027 struct sleepinfo {
2028 void *ident;
2029 int timedout;
2030 };
2031
2032 static void
2033 precise_sleep_intr(systimer_t info, int in_ipi, struct intrframe *frame)
2034 {
2035 struct sleepinfo *si;
2036
2037 si = info->data;
2038 si->timedout = 1;
2039 wakeup(si->ident);
2040 }
2041
2042 static int
2043 precise_sleep(void *ident, int flags, const char *wmesg, int us)
2044 {
2045 struct systimer info;
2046 struct sleepinfo si = {
2047 .ident = ident,
2048 .timedout = 0,
2049 };
2050 int r;
2051
2052 tsleep_interlock(ident, flags);
2053 systimer_init_oneshot(&info, precise_sleep_intr, &si,
2054 us == 0 ? 1 : us);
2055 r = tsleep(ident, flags | PINTERLOCKED, wmesg, 0);
2056 systimer_del(&info);
2057 if (si.timedout)
2058 r = EWOULDBLOCK;
2059
2060 return r;
2061 }
DragonFly BSD