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kqueue: Make EVFILT_USER event behaviour more consistent.
[dragonfly.git] / sys / kern / kern_event.c
blobe776ce55ef7d68effbd9c0b74cc56ea12be73eaa
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
53 #include <sys/thread2.h>
54 #include <sys/file2.h>
55 #include <sys/mplock2.h>
56
57 #define EVENT_REGISTER 1
58 #define EVENT_PROCESS 2
59
60 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
61
62 struct kevent_copyin_args {
63 struct kevent_args *ka;
64 int pchanges;
65 };
66
67 #define KNOTE_CACHE_MAX 8
68
69 struct knote_cache_list {
70 struct klist knote_cache;
71 int knote_cache_cnt;
72 } __cachealign;
73
74 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
75 struct knote *marker);
76 static int kqueue_read(struct file *fp, struct uio *uio,
77 struct ucred *cred, int flags);
78 static int kqueue_write(struct file *fp, struct uio *uio,
79 struct ucred *cred, int flags);
80 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
81 struct ucred *cred, struct sysmsg *msg);
82 static int kqueue_kqfilter(struct file *fp, struct knote *kn);
83 static int kqueue_stat(struct file *fp, struct stat *st,
84 struct ucred *cred);
85 static int kqueue_close(struct file *fp);
86 static void kqueue_wakeup(struct kqueue *kq);
87 static int filter_attach(struct knote *kn);
88 static int filter_event(struct knote *kn, long hint);
89
90 /*
91 * MPSAFE
92 */
93 static struct fileops kqueueops = {
94 .fo_read = kqueue_read,
95 .fo_write = kqueue_write,
96 .fo_ioctl = kqueue_ioctl,
97 .fo_kqfilter = kqueue_kqfilter,
98 .fo_stat = kqueue_stat,
99 .fo_close = kqueue_close,
100 .fo_shutdown = nofo_shutdown
101 };
102
103 static void knote_attach(struct knote *kn);
104 static void knote_drop(struct knote *kn);
105 static void knote_detach_and_drop(struct knote *kn);
106 static void knote_enqueue(struct knote *kn);
107 static void knote_dequeue(struct knote *kn);
108 static struct knote *knote_alloc(void);
109 static void knote_free(struct knote *kn);
110
111 static void precise_sleep_intr(systimer_t info, int in_ipi,
112 struct intrframe *frame);
113 static int precise_sleep(void *ident, int flags, const char *wmesg,
114 int us);
115
116 static void filt_kqdetach(struct knote *kn);
117 static int filt_kqueue(struct knote *kn, long hint);
118 static int filt_procattach(struct knote *kn);
119 static void filt_procdetach(struct knote *kn);
120 static int filt_proc(struct knote *kn, long hint);
121 static int filt_fileattach(struct knote *kn);
122 static void filt_timerexpire(void *knx);
123 static int filt_timerattach(struct knote *kn);
124 static void filt_timerdetach(struct knote *kn);
125 static int filt_timer(struct knote *kn, long hint);
126 static int filt_userattach(struct knote *kn);
127 static void filt_userdetach(struct knote *kn);
128 static int filt_user(struct knote *kn, long hint);
129 static void filt_usertouch(struct knote *kn, struct kevent *kev,
130 u_long type);
131 static int filt_fsattach(struct knote *kn);
132 static void filt_fsdetach(struct knote *kn);
133 static int filt_fs(struct knote *kn, long hint);
134
135 static struct filterops file_filtops =
136 { FILTEROP_ISFD | FILTEROP_MPSAFE, filt_fileattach, NULL, NULL };
137 static struct filterops kqread_filtops =
138 { FILTEROP_ISFD | FILTEROP_MPSAFE, NULL, filt_kqdetach, filt_kqueue };
139 static struct filterops proc_filtops =
140 { FILTEROP_MPSAFE, filt_procattach, filt_procdetach, filt_proc };
141 static struct filterops timer_filtops =
142 { FILTEROP_MPSAFE, filt_timerattach, filt_timerdetach, filt_timer };
143 static struct filterops user_filtops =
144 { FILTEROP_MPSAFE, filt_userattach, filt_userdetach, filt_user };
145 static struct filterops fs_filtops =
146 { FILTEROP_MPSAFE, filt_fsattach, filt_fsdetach, filt_fs };
147
148 static int kq_ncallouts = 0;
149 static int kq_calloutmax = (4 * 1024);
150 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
151 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
152 static int kq_checkloop = 1000000;
153 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW,
154 &kq_checkloop, 0, "Maximum number of loops for kqueue scan");
155 static int kq_sleep_threshold = 20000;
156 SYSCTL_INT(_kern, OID_AUTO, kq_sleep_threshold, CTLFLAG_RW,
157 &kq_sleep_threshold, 0, "Minimum sleep duration without busy-looping");
158
159 #define KNOTE_ACTIVATE(kn) do { \
160 kn->kn_status |= KN_ACTIVE; \
161 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \
162 knote_enqueue(kn); \
163 } while(0)
164
165 #define KN_HASHSIZE 64 /* XXX should be tunable */
166 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask))
167
168 extern struct filterops aio_filtops;
169 extern struct filterops sig_filtops;
170
171 /*
172 * Table for for all system-defined filters.
173 */
174 static struct filterops *sysfilt_ops[] = {
175 &file_filtops, /* EVFILT_READ */
176 &file_filtops, /* EVFILT_WRITE */
177 &aio_filtops, /* EVFILT_AIO */
178 &file_filtops, /* EVFILT_VNODE */
179 &proc_filtops, /* EVFILT_PROC */
180 &sig_filtops, /* EVFILT_SIGNAL */
181 &timer_filtops, /* EVFILT_TIMER */
182 &file_filtops, /* EVFILT_EXCEPT */
183 &user_filtops, /* EVFILT_USER */
184 &fs_filtops, /* EVFILT_FS */
185 };
186
187 static struct knote_cache_list knote_cache_lists[MAXCPU];
188
189 /*
190 * Acquire a knote, return non-zero on success, 0 on failure.
191 *
192 * If we cannot acquire the knote we sleep and return 0. The knote
193 * may be stale on return in this case and the caller must restart
194 * whatever loop they are in.
195 *
196 * Related kq token must be held.
197 */
198 static __inline int
199 knote_acquire(struct knote *kn)
200 {
201 if (kn->kn_status & KN_PROCESSING) {
202 kn->kn_status |= KN_WAITING | KN_REPROCESS;
203 tsleep(kn, 0, "kqepts", hz);
204 /* knote may be stale now */
205 return(0);
206 }
207 kn->kn_status |= KN_PROCESSING;
208 return(1);
209 }
210
211 /*
212 * Release an acquired knote, clearing KN_PROCESSING and handling any
213 * KN_REPROCESS events.
214 *
215 * Caller must be holding the related kq token
216 *
217 * Non-zero is returned if the knote is destroyed or detached.
218 */
219 static __inline int
220 knote_release(struct knote *kn)
221 {
222 int ret;
223
224 while (kn->kn_status & KN_REPROCESS) {
225 kn->kn_status &= ~KN_REPROCESS;
226 if (kn->kn_status & KN_WAITING) {
227 kn->kn_status &= ~KN_WAITING;
228 wakeup(kn);
229 }
230 if (kn->kn_status & KN_DELETING) {
231 knote_detach_and_drop(kn);
232 return(1);
233 /* NOT REACHED */
234 }
235 if (filter_event(kn, 0))
236 KNOTE_ACTIVATE(kn);
237 }
238 if (kn->kn_status & KN_DETACHED)
239 ret = 1;
240 else
241 ret = 0;
242 kn->kn_status &= ~KN_PROCESSING;
243 /* kn should not be accessed anymore */
244 return ret;
245 }
246
247 static int
248 filt_fileattach(struct knote *kn)
249 {
250 return (fo_kqfilter(kn->kn_fp, kn));
251 }
252
253 /*
254 * MPSAFE
255 */
256 static int
257 kqueue_kqfilter(struct file *fp, struct knote *kn)
258 {
259 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
260
261 if (kn->kn_filter != EVFILT_READ)
262 return (EOPNOTSUPP);
263
264 kn->kn_fop = &kqread_filtops;
265 knote_insert(&kq->kq_kqinfo.ki_note, kn);
266 return (0);
267 }
268
269 static void
270 filt_kqdetach(struct knote *kn)
271 {
272 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
273
274 knote_remove(&kq->kq_kqinfo.ki_note, kn);
275 }
276
277 /*ARGSUSED*/
278 static int
279 filt_kqueue(struct knote *kn, long hint)
280 {
281 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
282
283 kn->kn_data = kq->kq_count;
284 return (kn->kn_data > 0);
285 }
286
287 static int
288 filt_procattach(struct knote *kn)
289 {
290 struct proc *p;
291 int immediate;
292
293 immediate = 0;
294 p = pfind(kn->kn_id);
295 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
296 p = zpfind(kn->kn_id);
297 immediate = 1;
298 }
299 if (p == NULL) {
300 return (ESRCH);
301 }
302 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) {
303 if (p)
304 PRELE(p);
305 return (EACCES);
306 }
307
308 lwkt_gettoken(&p->p_token);
309 kn->kn_ptr.p_proc = p;
310 kn->kn_flags |= EV_CLEAR; /* automatically set */
311
312 /*
313 * internal flag indicating registration done by kernel
314 */
315 if (kn->kn_flags & EV_FLAG1) {
316 kn->kn_data = kn->kn_sdata; /* ppid */
317 kn->kn_fflags = NOTE_CHILD;
318 kn->kn_flags &= ~EV_FLAG1;
319 }
320
321 knote_insert(&p->p_klist, kn);
322
323 /*
324 * Immediately activate any exit notes if the target process is a
325 * zombie. This is necessary to handle the case where the target
326 * process, e.g. a child, dies before the kevent is negistered.
327 */
328 if (immediate && filt_proc(kn, NOTE_EXIT))
329 KNOTE_ACTIVATE(kn);
330 lwkt_reltoken(&p->p_token);
331 PRELE(p);
332
333 return (0);
334 }
335
336 /*
337 * The knote may be attached to a different process, which may exit,
338 * leaving nothing for the knote to be attached to. So when the process
339 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
340 * it will be deleted when read out. However, as part of the knote deletion,
341 * this routine is called, so a check is needed to avoid actually performing
342 * a detach, because the original process does not exist any more.
343 */
344 static void
345 filt_procdetach(struct knote *kn)
346 {
347 struct proc *p;
348
349 if (kn->kn_status & KN_DETACHED)
350 return;
351 p = kn->kn_ptr.p_proc;
352 knote_remove(&p->p_klist, kn);
353 }
354
355 static int
356 filt_proc(struct knote *kn, long hint)
357 {
358 u_int event;
359
360 /*
361 * mask off extra data
362 */
363 event = (u_int)hint & NOTE_PCTRLMASK;
364
365 /*
366 * if the user is interested in this event, record it.
367 */
368 if (kn->kn_sfflags & event)
369 kn->kn_fflags |= event;
370
371 /*
372 * Process is gone, so flag the event as finished. Detach the
373 * knote from the process now because the process will be poof,
374 * gone later on.
375 */
376 if (event == NOTE_EXIT) {
377 struct proc *p = kn->kn_ptr.p_proc;
378 if ((kn->kn_status & KN_DETACHED) == 0) {
379 PHOLD(p);
380 knote_remove(&p->p_klist, kn);
381 kn->kn_status |= KN_DETACHED;
382 kn->kn_data = p->p_xstat;
383 kn->kn_ptr.p_proc = NULL;
384 PRELE(p);
385 }
386 kn->kn_flags |= (EV_EOF | EV_NODATA | EV_ONESHOT);
387 return (1);
388 }
389
390 /*
391 * process forked, and user wants to track the new process,
392 * so attach a new knote to it, and immediately report an
393 * event with the parent's pid.
394 */
395 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) {
396 struct kevent kev;
397 int error;
398
399 /*
400 * register knote with new process.
401 */
402 kev.ident = hint & NOTE_PDATAMASK; /* pid */
403 kev.filter = kn->kn_filter;
404 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
405 kev.fflags = kn->kn_sfflags;
406 kev.data = kn->kn_id; /* parent */
407 kev.udata = kn->kn_kevent.udata; /* preserve udata */
408 error = kqueue_register(kn->kn_kq, &kev);
409 if (error)
410 kn->kn_fflags |= NOTE_TRACKERR;
411 }
412
413 return (kn->kn_fflags != 0);
414 }
415
416 static void
417 filt_timerreset(struct knote *kn)
418 {
419 struct callout *calloutp;
420 struct timeval tv;
421 int tticks;
422
423 tv.tv_sec = kn->kn_sdata / 1000;
424 tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
425 tticks = tvtohz_high(&tv);
426 calloutp = (struct callout *)kn->kn_hook;
427 callout_reset(calloutp, tticks, filt_timerexpire, kn);
428 }
429
430 /*
431 * The callout interlocks with callout_terminate() but can still
432 * race a deletion so if KN_DELETING is set we just don't touch
433 * the knote.
434 */
435 static void
436 filt_timerexpire(void *knx)
437 {
438 struct knote *kn = knx;
439 struct kqueue *kq = kn->kn_kq;
440
441 lwkt_getpooltoken(kq);
442
443 /*
444 * Open knote_acquire(), since we can't sleep in callout,
445 * however, we do need to record this expiration.
446 */
447 kn->kn_data++;
448 if (kn->kn_status & KN_PROCESSING) {
449 kn->kn_status |= KN_REPROCESS;
450 if ((kn->kn_status & KN_DELETING) == 0 &&
451 (kn->kn_flags & EV_ONESHOT) == 0)
452 filt_timerreset(kn);
453 lwkt_relpooltoken(kq);
454 return;
455 }
456 KASSERT((kn->kn_status & KN_DELETING) == 0,
457 ("acquire a deleting knote %#x", kn->kn_status));
458 kn->kn_status |= KN_PROCESSING;
459
460 KNOTE_ACTIVATE(kn);
461 if ((kn->kn_flags & EV_ONESHOT) == 0)
462 filt_timerreset(kn);
463
464 knote_release(kn);
465
466 lwkt_relpooltoken(kq);
467 }
468
469 /*
470 * data contains amount of time to sleep, in milliseconds
471 */
472 static int
473 filt_timerattach(struct knote *kn)
474 {
475 struct callout *calloutp;
476 int prev_ncallouts;
477
478 prev_ncallouts = atomic_fetchadd_int(&kq_ncallouts, 1);
479 if (prev_ncallouts >= kq_calloutmax) {
480 atomic_subtract_int(&kq_ncallouts, 1);
481 kn->kn_hook = NULL;
482 return (ENOMEM);
483 }
484
485 kn->kn_flags |= EV_CLEAR; /* automatically set */
486 calloutp = kmalloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
487 callout_init_mp(calloutp);
488 kn->kn_hook = (caddr_t)calloutp;
489
490 filt_timerreset(kn);
491 return (0);
492 }
493
494 /*
495 * This function is called with the knote flagged locked but it is
496 * still possible to race a callout event due to the callback blocking.
497 * We must call callout_terminate() instead of callout_stop() to deal
498 * with the race.
499 */
500 static void
501 filt_timerdetach(struct knote *kn)
502 {
503 struct callout *calloutp;
504
505 calloutp = (struct callout *)kn->kn_hook;
506 callout_terminate(calloutp);
507 kn->kn_hook = NULL;
508 kfree(calloutp, M_KQUEUE);
509 atomic_subtract_int(&kq_ncallouts, 1);
510 }
511
512 static int
513 filt_timer(struct knote *kn, long hint)
514 {
515 return (kn->kn_data != 0);
516 }
517
518 /*
519 * EVFILT_USER
520 */
521 static int
522 filt_userattach(struct knote *kn)
523 {
524 u_int ffctrl;
525
526 kn->kn_hook = NULL;
527 if (kn->kn_sfflags & NOTE_TRIGGER)
528 kn->kn_ptr.hookid = 1;
529 else
530 kn->kn_ptr.hookid = 0;
531
532 ffctrl = kn->kn_sfflags & NOTE_FFCTRLMASK;
533 kn->kn_sfflags &= NOTE_FFLAGSMASK;
534 switch (ffctrl) {
535 case NOTE_FFNOP:
536 break;
537
538 case NOTE_FFAND:
539 kn->kn_fflags &= kn->kn_sfflags;
540 break;
541
542 case NOTE_FFOR:
543 kn->kn_fflags |= kn->kn_sfflags;
544 break;
545
546 case NOTE_FFCOPY:
547 kn->kn_fflags = kn->kn_sfflags;
548 break;
549
550 default:
551 /* XXX Return error? */
552 break;
553 }
554 /* We just happen to copy this value as well. Undocumented. */
555 kn->kn_data = kn->kn_sdata;
556
557 return 0;
558 }
559
560 static void
561 filt_userdetach(struct knote *kn)
562 {
563 /* nothing to do */
564 }
565
566 static int
567 filt_user(struct knote *kn, long hint)
568 {
569 return (kn->kn_ptr.hookid);
570 }
571
572 static void
573 filt_usertouch(struct knote *kn, struct kevent *kev, u_long type)
574 {
575 u_int ffctrl;
576
577 switch (type) {
578 case EVENT_REGISTER:
579 if (kev->fflags & NOTE_TRIGGER)
580 kn->kn_ptr.hookid = 1;
581
582 ffctrl = kev->fflags & NOTE_FFCTRLMASK;
583 kev->fflags &= NOTE_FFLAGSMASK;
584 switch (ffctrl) {
585 case NOTE_FFNOP:
586 break;
587
588 case NOTE_FFAND:
589 kn->kn_fflags &= kev->fflags;
590 break;
591
592 case NOTE_FFOR:
593 kn->kn_fflags |= kev->fflags;
594 break;
595
596 case NOTE_FFCOPY:
597 kn->kn_fflags = kev->fflags;
598 break;
599
600 default:
601 /* XXX Return error? */
602 break;
603 }
604 /* We just happen to copy this value as well. Undocumented. */
605 kn->kn_data = kev->data;
606
607 /*
608 * This is not the correct use of EV_CLEAR in an event
609 * modification, it should have been passed as a NOTE instead.
610 * But we need to maintain compatibility with Apple & FreeBSD.
611 *
612 * Note however that EV_CLEAR can still be used when doing
613 * the initial registration of the event and works as expected
614 * (clears the event on reception).
615 */
616 if (kev->flags & EV_CLEAR) {
617 kn->kn_ptr.hookid = 0;
618 /*
619 * Clearing kn->kn_data is fine, since it gets set
620 * every time anyway. We just shouldn't clear
621 * kn->kn_fflags here, since that would limit the
622 * possible uses of this API. NOTE_FFAND or
623 * NOTE_FFCOPY should be used for explicitly clearing
624 * kn->kn_fflags.
625 */
626 kn->kn_data = 0;
627 }
628 break;
629
630 case EVENT_PROCESS:
631 *kev = kn->kn_kevent;
632 kev->fflags = kn->kn_fflags;
633 kev->data = kn->kn_data;
634 if (kn->kn_flags & EV_CLEAR) {
635 kn->kn_ptr.hookid = 0;
636 /* kn_data, kn_fflags handled by parent */
637 }
638 break;
639
640 default:
641 panic("filt_usertouch() - invalid type (%ld)", type);
642 break;
643 }
644 }
645
646 /*
647 * EVFILT_FS
648 */
649 struct klist fs_klist = SLIST_HEAD_INITIALIZER(&fs_klist);
650
651 static int
652 filt_fsattach(struct knote *kn)
653 {
654 kn->kn_flags |= EV_CLEAR;
655 knote_insert(&fs_klist, kn);
656
657 return (0);
658 }
659
660 static void
661 filt_fsdetach(struct knote *kn)
662 {
663 knote_remove(&fs_klist, kn);
664 }
665
666 static int
667 filt_fs(struct knote *kn, long hint)
668 {
669 kn->kn_fflags |= hint;
670 return (kn->kn_fflags != 0);
671 }
672
673 /*
674 * Initialize a kqueue.
675 *
676 * NOTE: The lwp/proc code initializes a kqueue for select/poll ops.
677 *
678 * MPSAFE
679 */
680 void
681 kqueue_init(struct kqueue *kq, struct filedesc *fdp)
682 {
683 TAILQ_INIT(&kq->kq_knpend);
684 TAILQ_INIT(&kq->kq_knlist);
685 kq->kq_count = 0;
686 kq->kq_fdp = fdp;
687 SLIST_INIT(&kq->kq_kqinfo.ki_note);
688 }
689
690 /*
691 * Terminate a kqueue. Freeing the actual kq itself is left up to the
692 * caller (it might be embedded in a lwp so we don't do it here).
693 *
694 * The kq's knlist must be completely eradicated so block on any
695 * processing races.
696 */
697 void
698 kqueue_terminate(struct kqueue *kq)
699 {
700 struct knote *kn;
701
702 lwkt_getpooltoken(kq);
703 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL) {
704 if (knote_acquire(kn))
705 knote_detach_and_drop(kn);
706 }
707 lwkt_relpooltoken(kq);
708
709 if (kq->kq_knhash) {
710 hashdestroy(kq->kq_knhash, M_KQUEUE, kq->kq_knhashmask);
711 kq->kq_knhash = NULL;
712 kq->kq_knhashmask = 0;
713 }
714 }
715
716 /*
717 * MPSAFE
718 */
719 int
720 sys_kqueue(struct kqueue_args *uap)
721 {
722 struct thread *td = curthread;
723 struct kqueue *kq;
724 struct file *fp;
725 int fd, error;
726
727 error = falloc(td->td_lwp, &fp, &fd);
728 if (error)
729 return (error);
730 fp->f_flag = FREAD | FWRITE;
731 fp->f_type = DTYPE_KQUEUE;
732 fp->f_ops = &kqueueops;
733
734 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO);
735 kqueue_init(kq, td->td_proc->p_fd);
736 fp->f_data = kq;
737
738 fsetfd(kq->kq_fdp, fp, fd);
739 uap->sysmsg_result = fd;
740 fdrop(fp);
741 return (error);
742 }
743
744 /*
745 * Copy 'count' items into the destination list pointed to by uap->eventlist.
746 */
747 static int
748 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res)
749 {
750 struct kevent_copyin_args *kap;
751 int error;
752
753 kap = (struct kevent_copyin_args *)arg;
754
755 error = copyout(kevp, kap->ka->eventlist, count * sizeof(*kevp));
756 if (error == 0) {
757 kap->ka->eventlist += count;
758 *res += count;
759 } else {
760 *res = -1;
761 }
762
763 return (error);
764 }
765
766 /*
767 * Copy at most 'max' items from the list pointed to by kap->changelist,
768 * return number of items in 'events'.
769 */
770 static int
771 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events)
772 {
773 struct kevent_copyin_args *kap;
774 int error, count;
775
776 kap = (struct kevent_copyin_args *)arg;
777
778 count = min(kap->ka->nchanges - kap->pchanges, max);
779 error = copyin(kap->ka->changelist, kevp, count * sizeof *kevp);
780 if (error == 0) {
781 kap->ka->changelist += count;
782 kap->pchanges += count;
783 *events = count;
784 }
785
786 return (error);
787 }
788
789 /*
790 * MPSAFE
791 */
792 int
793 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap,
794 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn,
795 struct timespec *tsp_in, int flags)
796 {
797 struct kevent *kevp;
798 struct timespec *tsp, ats;
799 int i, n, total, error, nerrors = 0;
800 int lres;
801 int limit = kq_checkloop;
802 struct kevent kev[KQ_NEVENTS];
803 struct knote marker;
804 struct lwkt_token *tok;
805
806 if (tsp_in == NULL || tsp_in->tv_sec || tsp_in->tv_nsec)
807 atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC);
808
809 tsp = tsp_in;
810 *res = 0;
811
812 for (;;) {
813 n = 0;
814 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n);
815 if (error)
816 return error;
817 if (n == 0)
818 break;
819 for (i = 0; i < n; i++) {
820 kevp = &kev[i];
821 kevp->flags &= ~EV_SYSFLAGS;
822 error = kqueue_register(kq, kevp);
823
824 /*
825 * If a registration returns an error we
826 * immediately post the error. The kevent()
827 * call itself will fail with the error if
828 * no space is available for posting.
829 *
830 * Such errors normally bypass the timeout/blocking
831 * code. However, if the copyoutfn function refuses
832 * to post the error (see sys_poll()), then we
833 * ignore it too.
834 */
835 if (error || (kevp->flags & EV_RECEIPT)) {
836 kevp->flags = EV_ERROR;
837 kevp->data = error;
838 lres = *res;
839 kevent_copyoutfn(uap, kevp, 1, res);
840 if (*res < 0) {
841 return error;
842 } else if (lres != *res) {
843 nevents--;
844 nerrors++;
845 }
846 }
847 }
848 }
849 if (nerrors)
850 return 0;
851
852 /*
853 * Acquire/wait for events - setup timeout
854 */
855 if (tsp != NULL) {
856 if (tsp->tv_sec || tsp->tv_nsec) {
857 getnanouptime(&ats);
858 timespecadd(tsp, &ats); /* tsp = target time */
859 }
860 }
861
862 /*
863 * Loop as required.
864 *
865 * Collect as many events as we can. Sleeping on successive
866 * loops is disabled if copyoutfn has incremented (*res).
867 *
868 * The loop stops if an error occurs, all events have been
869 * scanned (the marker has been reached), or fewer than the
870 * maximum number of events is found.
871 *
872 * The copyoutfn function does not have to increment (*res) in
873 * order for the loop to continue.
874 *
875 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents.
876 */
877 total = 0;
878 error = 0;
879 marker.kn_filter = EVFILT_MARKER;
880 marker.kn_status = KN_PROCESSING;
881 tok = lwkt_token_pool_lookup(kq);
882 lwkt_gettoken(tok);
883 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
884 lwkt_reltoken(tok);
885 while ((n = nevents - total) > 0) {
886 if (n > KQ_NEVENTS)
887 n = KQ_NEVENTS;
888
889 /*
890 * If no events are pending sleep until timeout (if any)
891 * or an event occurs.
892 *
893 * After the sleep completes the marker is moved to the
894 * end of the list, making any received events available
895 * to our scan.
896 */
897 if (kq->kq_count == 0 && *res == 0) {
898 int timeout, ustimeout = 0;
899
900 if (tsp == NULL) {
901 timeout = 0;
902 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) {
903 error = EWOULDBLOCK;
904 break;
905 } else {
906 struct timespec atx = *tsp;
907
908 getnanouptime(&ats);
909 timespecsub(&atx, &ats);
910 if (atx.tv_sec < 0) {
911 error = EWOULDBLOCK;
912 break;
913 } else {
914 timeout = atx.tv_sec > 24 * 60 * 60 ?
915 24 * 60 * 60 * hz :
916 tstohz_high(&atx);
917 }
918 if (flags & KEVENT_TIMEOUT_PRECISE &&
919 timeout != 0) {
920 if (atx.tv_sec == 0 &&
921 atx.tv_nsec < kq_sleep_threshold) {
922 DELAY(atx.tv_nsec / 1000);
923 error = EWOULDBLOCK;
924 break;
925 } else if (atx.tv_sec < 2000) {
926 ustimeout = atx.tv_sec *
927 1000000 + atx.tv_nsec/1000;
928 } else {
929 ustimeout = 2000000000;
930 }
931 }
932 }
933
934 lwkt_gettoken(tok);
935 if (kq->kq_count == 0) {
936 kq->kq_sleep_cnt++;
937 if (__predict_false(kq->kq_sleep_cnt == 0)) {
938 /*
939 * Guard against possible wrapping. And
940 * set it to 2, so that kqueue_wakeup()
941 * can wake everyone up.
942 */
943 kq->kq_sleep_cnt = 2;
944 }
945 if ((flags & KEVENT_TIMEOUT_PRECISE) &&
946 timeout != 0) {
947 error = precise_sleep(kq, PCATCH,
948 "kqread", ustimeout);
949 } else {
950 error = tsleep(kq, PCATCH, "kqread",
951 timeout);
952 }
953
954 /* don't restart after signals... */
955 if (error == ERESTART)
956 error = EINTR;
957 if (error) {
958 lwkt_reltoken(tok);
959 break;
960 }
961
962 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
963 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker,
964 kn_tqe);
965 }
966 lwkt_reltoken(tok);
967 }
968
969 /*
970 * Process all received events
971 * Account for all non-spurious events in our total
972 */
973 i = kqueue_scan(kq, kev, n, &marker);
974 if (i) {
975 lres = *res;
976 error = kevent_copyoutfn(uap, kev, i, res);
977 total += *res - lres;
978 if (error)
979 break;
980 }
981 if (limit && --limit == 0)
982 panic("kqueue: checkloop failed i=%d", i);
983
984 /*
985 * Normally when fewer events are returned than requested
986 * we can stop. However, if only spurious events were
987 * collected the copyout will not bump (*res) and we have
988 * to continue.
989 */
990 if (i < n && *res)
991 break;
992
993 /*
994 * Deal with an edge case where spurious events can cause
995 * a loop to occur without moving the marker. This can
996 * prevent kqueue_scan() from picking up new events which
997 * race us. We must be sure to move the marker for this
998 * case.
999 *
1000 * NOTE: We do not want to move the marker if events
1001 * were scanned because normal kqueue operations
1002 * may reactivate events. Moving the marker in
1003 * that case could result in duplicates for the
1004 * same event.
1005 */
1006 if (i == 0) {
1007 lwkt_gettoken(tok);
1008 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
1009 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
1010 lwkt_reltoken(tok);
1011 }
1012 }
1013 lwkt_gettoken(tok);
1014 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
1015 lwkt_reltoken(tok);
1016
1017 /* Timeouts do not return EWOULDBLOCK. */
1018 if (error == EWOULDBLOCK)
1019 error = 0;
1020 return error;
1021 }
1022
1023 /*
1024 * MPALMOSTSAFE
1025 */
1026 int
1027 sys_kevent(struct kevent_args *uap)
1028 {
1029 struct thread *td = curthread;
1030 struct proc *p = td->td_proc;
1031 struct timespec ts, *tsp;
1032 struct kqueue *kq;
1033 struct file *fp = NULL;
1034 struct kevent_copyin_args *kap, ka;
1035 int error;
1036
1037 if (uap->timeout) {
1038 error = copyin(uap->timeout, &ts, sizeof(ts));
1039 if (error)
1040 return (error);
1041 tsp = &ts;
1042 } else {
1043 tsp = NULL;
1044 }
1045 fp = holdfp(p->p_fd, uap->fd, -1);
1046 if (fp == NULL)
1047 return (EBADF);
1048 if (fp->f_type != DTYPE_KQUEUE) {
1049 fdrop(fp);
1050 return (EBADF);
1051 }
1052
1053 kq = (struct kqueue *)fp->f_data;
1054
1055 kap = &ka;
1056 kap->ka = uap;
1057 kap->pchanges = 0;
1058
1059 error = kern_kevent(kq, uap->nevents, &uap->sysmsg_result, kap,
1060 kevent_copyin, kevent_copyout, tsp, 0);
1061
1062 fdrop(fp);
1063
1064 return (error);
1065 }
1066
1067 int
1068 kqueue_register(struct kqueue *kq, struct kevent *kev)
1069 {
1070 struct filedesc *fdp = kq->kq_fdp;
1071 struct klist *list = NULL;
1072 struct filterops *fops;
1073 struct file *fp = NULL;
1074 struct knote *kn = NULL;
1075 struct thread *td;
1076 int error = 0;
1077 struct knote_cache_list *cache_list;
1078
1079 if (kev->filter < 0) {
1080 if (kev->filter + EVFILT_SYSCOUNT < 0)
1081 return (EINVAL);
1082 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */
1083 } else {
1084 /*
1085 * XXX
1086 * filter attach routine is responsible for insuring that
1087 * the identifier can be attached to it.
1088 */
1089 return (EINVAL);
1090 }
1091
1092 if (fops->f_flags & FILTEROP_ISFD) {
1093 /* validate descriptor */
1094 fp = holdfp(fdp, kev->ident, -1);
1095 if (fp == NULL)
1096 return (EBADF);
1097 }
1098
1099 cache_list = &knote_cache_lists[mycpuid];
1100 if (SLIST_EMPTY(&cache_list->knote_cache)) {
1101 struct knote *new_kn;
1102
1103 new_kn = knote_alloc();
1104 crit_enter();
1105 SLIST_INSERT_HEAD(&cache_list->knote_cache, new_kn, kn_link);
1106 cache_list->knote_cache_cnt++;
1107 crit_exit();
1108 }
1109
1110 td = curthread;
1111 lwkt_getpooltoken(kq);
1112
1113 /*
1114 * Make sure that only one thread can register event on this kqueue,
1115 * so that we would not suffer any race, even if the registration
1116 * blocked, i.e. kq token was released, and the kqueue was shared
1117 * between threads (this should be rare though).
1118 */
1119 while (__predict_false(kq->kq_regtd != NULL && kq->kq_regtd != td)) {
1120 kq->kq_state |= KQ_REGWAIT;
1121 tsleep(&kq->kq_regtd, 0, "kqreg", 0);
1122 }
1123 if (__predict_false(kq->kq_regtd != NULL)) {
1124 /* Recursive calling of kqueue_register() */
1125 td = NULL;
1126 } else {
1127 /* Owner of the kq_regtd, i.e. td != NULL */
1128 kq->kq_regtd = td;
1129 }
1130
1131 if (fp != NULL) {
1132 list = &fp->f_klist;
1133 } else if (kq->kq_knhashmask) {
1134 list = &kq->kq_knhash[
1135 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
1136 }
1137 if (list != NULL) {
1138 lwkt_getpooltoken(list);
1139 again:
1140 SLIST_FOREACH(kn, list, kn_link) {
1141 if (kn->kn_kq == kq &&
1142 kn->kn_filter == kev->filter &&
1143 kn->kn_id == kev->ident) {
1144 if (knote_acquire(kn) == 0)
1145 goto again;
1146 break;
1147 }
1148 }
1149 lwkt_relpooltoken(list);
1150 }
1151
1152 /*
1153 * NOTE: At this point if kn is non-NULL we will have acquired
1154 * it and set KN_PROCESSING.
1155 */
1156 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) {
1157 error = ENOENT;
1158 goto done;
1159 }
1160
1161 /*
1162 * kn now contains the matching knote, or NULL if no match
1163 */
1164 if (kev->flags & EV_ADD) {
1165 if (kn == NULL) {
1166 crit_enter();
1167 kn = SLIST_FIRST(&cache_list->knote_cache);
1168 if (kn == NULL) {
1169 crit_exit();
1170 kn = knote_alloc();
1171 } else {
1172 SLIST_REMOVE_HEAD(&cache_list->knote_cache,
1173 kn_link);
1174 cache_list->knote_cache_cnt--;
1175 crit_exit();
1176 }
1177 kn->kn_fp = fp;
1178 kn->kn_kq = kq;
1179 kn->kn_fop = fops;
1180
1181 /*
1182 * apply reference count to knote structure, and
1183 * do not release it at the end of this routine.
1184 */
1185 fp = NULL;
1186
1187 kn->kn_sfflags = kev->fflags;
1188 kn->kn_sdata = kev->data;
1189 kev->fflags = 0;
1190 kev->data = 0;
1191 kn->kn_kevent = *kev;
1192
1193 /*
1194 * KN_PROCESSING prevents the knote from getting
1195 * ripped out from under us while we are trying
1196 * to attach it, in case the attach blocks.
1197 */
1198 kn->kn_status = KN_PROCESSING;
1199 knote_attach(kn);
1200 if ((error = filter_attach(kn)) != 0) {
1201 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1202 knote_drop(kn);
1203 goto done;
1204 }
1205
1206 /*
1207 * Interlock against close races which either tried
1208 * to remove our knote while we were blocked or missed
1209 * it entirely prior to our attachment. We do not
1210 * want to end up with a knote on a closed descriptor.
1211 */
1212 if ((fops->f_flags & FILTEROP_ISFD) &&
1213 checkfdclosed(fdp, kev->ident, kn->kn_fp)) {
1214 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1215 }
1216 } else {
1217 /*
1218 * The user may change some filter values after the
1219 * initial EV_ADD, but doing so will not reset any
1220 * filter which have already been triggered.
1221 */
1222 KKASSERT(kn->kn_status & KN_PROCESSING);
1223 if (fops == &user_filtops) {
1224 filt_usertouch(kn, kev, EVENT_REGISTER);
1225 } else {
1226 kn->kn_sfflags = kev->fflags;
1227 kn->kn_sdata = kev->data;
1228 kn->kn_kevent.udata = kev->udata;
1229 }
1230 }
1231
1232 /*
1233 * Execute the filter event to immediately activate the
1234 * knote if necessary. If reprocessing events are pending
1235 * due to blocking above we do not run the filter here
1236 * but instead let knote_release() do it. Otherwise we
1237 * might run the filter on a deleted event.
1238 */
1239 if ((kn->kn_status & KN_REPROCESS) == 0) {
1240 if (filter_event(kn, 0))
1241 KNOTE_ACTIVATE(kn);
1242 }
1243 } else if (kev->flags & EV_DELETE) {
1244 /*
1245 * Delete the existing knote
1246 */
1247 knote_detach_and_drop(kn);
1248 goto done;
1249 } else {
1250 /*
1251 * Modify an existing event.
1252 *
1253 * The user may change some filter values after the
1254 * initial EV_ADD, but doing so will not reset any
1255 * filter which have already been triggered.
1256 */
1257 KKASSERT(kn->kn_status & KN_PROCESSING);
1258 if (fops == &user_filtops) {
1259 filt_usertouch(kn, kev, EVENT_REGISTER);
1260 } else {
1261 kn->kn_sfflags = kev->fflags;
1262 kn->kn_sdata = kev->data;
1263 kn->kn_kevent.udata = kev->udata;
1264 }
1265
1266 /*
1267 * Execute the filter event to immediately activate the
1268 * knote if necessary. If reprocessing events are pending
1269 * due to blocking above we do not run the filter here
1270 * but instead let knote_release() do it. Otherwise we
1271 * might run the filter on a deleted event.
1272 */
1273 if ((kn->kn_status & KN_REPROCESS) == 0) {
1274 if (filter_event(kn, 0))
1275 KNOTE_ACTIVATE(kn);
1276 }
1277 }
1278
1279 /*
1280 * Disablement does not deactivate a knote here.
1281 */
1282 if ((kev->flags & EV_DISABLE) &&
1283 ((kn->kn_status & KN_DISABLED) == 0)) {
1284 kn->kn_status |= KN_DISABLED;
1285 }
1286
1287 /*
1288 * Re-enablement may have to immediately enqueue an active knote.
1289 */
1290 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
1291 kn->kn_status &= ~KN_DISABLED;
1292 if ((kn->kn_status & KN_ACTIVE) &&
1293 ((kn->kn_status & KN_QUEUED) == 0)) {
1294 knote_enqueue(kn);
1295 }
1296 }
1297
1298 /*
1299 * Handle any required reprocessing
1300 */
1301 knote_release(kn);
1302 /* kn may be invalid now */
1303
1304 done:
1305 if (td != NULL) { /* Owner of the kq_regtd */
1306 kq->kq_regtd = NULL;
1307 if (__predict_false(kq->kq_state & KQ_REGWAIT)) {
1308 kq->kq_state &= ~KQ_REGWAIT;
1309 wakeup(&kq->kq_regtd);
1310 }
1311 }
1312 lwkt_relpooltoken(kq);
1313 if (fp != NULL)
1314 fdrop(fp);
1315 return (error);
1316 }
1317
1318 /*
1319 * Scan the kqueue, return the number of active events placed in kevp up
1320 * to count.
1321 *
1322 * Continuous mode events may get recycled, do not continue scanning past
1323 * marker unless no events have been collected.
1324 */
1325 static int
1326 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
1327 struct knote *marker)
1328 {
1329 struct knote *kn, local_marker;
1330 int total;
1331
1332 total = 0;
1333 local_marker.kn_filter = EVFILT_MARKER;
1334 local_marker.kn_status = KN_PROCESSING;
1335
1336 lwkt_getpooltoken(kq);
1337
1338 /*
1339 * Collect events.
1340 */
1341 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe);
1342 while (count) {
1343 kn = TAILQ_NEXT(&local_marker, kn_tqe);
1344 if (kn->kn_filter == EVFILT_MARKER) {
1345 /* Marker reached, we are done */
1346 if (kn == marker)
1347 break;
1348
1349 /* Move local marker past some other threads marker */
1350 kn = TAILQ_NEXT(kn, kn_tqe);
1351 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1352 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe);
1353 continue;
1354 }
1355
1356 /*
1357 * We can't skip a knote undergoing processing, otherwise
1358 * we risk not returning it when the user process expects
1359 * it should be returned. Sleep and retry.
1360 */
1361 if (knote_acquire(kn) == 0)
1362 continue;
1363
1364 /*
1365 * Remove the event for processing.
1366 *
1367 * WARNING! We must leave KN_QUEUED set to prevent the
1368 * event from being KNOTE_ACTIVATE()d while
1369 * the queue state is in limbo, in case we
1370 * block.
1371 */
1372 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
1373 kq->kq_count--;
1374
1375 /*
1376 * We have to deal with an extremely important race against
1377 * file descriptor close()s here. The file descriptor can
1378 * disappear MPSAFE, and there is a small window of
1379 * opportunity between that and the call to knote_fdclose().
1380 *
1381 * If we hit that window here while doselect or dopoll is
1382 * trying to delete a spurious event they will not be able
1383 * to match up the event against a knote and will go haywire.
1384 */
1385 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) &&
1386 checkfdclosed(kq->kq_fdp, kn->kn_kevent.ident, kn->kn_fp)) {
1387 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1388 }
1389
1390 if (kn->kn_status & KN_DISABLED) {
1391 /*
1392 * If disabled we ensure the event is not queued
1393 * but leave its active bit set. On re-enablement
1394 * the event may be immediately triggered.
1395 */
1396 kn->kn_status &= ~KN_QUEUED;
1397 } else if ((kn->kn_flags & EV_ONESHOT) == 0 &&
1398 (kn->kn_status & KN_DELETING) == 0 &&
1399 filter_event(kn, 0) == 0) {
1400 /*
1401 * If not running in one-shot mode and the event
1402 * is no longer present we ensure it is removed
1403 * from the queue and ignore it.
1404 */
1405 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
1406 } else {
1407 /*
1408 * Post the event
1409 */
1410 if (kn->kn_fop == &user_filtops)
1411 filt_usertouch(kn, kevp, EVENT_PROCESS);
1412 else
1413 *kevp = kn->kn_kevent;
1414 ++kevp;
1415 ++total;
1416 --count;
1417
1418 if (kn->kn_flags & EV_ONESHOT) {
1419 kn->kn_status &= ~KN_QUEUED;
1420 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1421 } else {
1422 if (kn->kn_flags & (EV_CLEAR | EV_DISPATCH)) {
1423 if (kn->kn_flags & EV_CLEAR) {
1424 kn->kn_data = 0;
1425 kn->kn_fflags = 0;
1426 }
1427 if (kn->kn_flags & EV_DISPATCH) {
1428 kn->kn_status |= KN_DISABLED;
1429 }
1430 kn->kn_status &= ~(KN_QUEUED |
1431 KN_ACTIVE);
1432 } else {
1433 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1434 kq->kq_count++;
1435 }
1436 }
1437 }
1438
1439 /*
1440 * Handle any post-processing states
1441 */
1442 knote_release(kn);
1443 }
1444 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1445
1446 lwkt_relpooltoken(kq);
1447 return (total);
1448 }
1449
1450 /*
1451 * XXX
1452 * This could be expanded to call kqueue_scan, if desired.
1453 *
1454 * MPSAFE
1455 */
1456 static int
1457 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1458 {
1459 return (ENXIO);
1460 }
1461
1462 /*
1463 * MPSAFE
1464 */
1465 static int
1466 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1467 {
1468 return (ENXIO);
1469 }
1470
1471 /*
1472 * MPALMOSTSAFE
1473 */
1474 static int
1475 kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
1476 struct ucred *cred, struct sysmsg *msg)
1477 {
1478 struct kqueue *kq;
1479 int error;
1480
1481 kq = (struct kqueue *)fp->f_data;
1482 lwkt_getpooltoken(kq);
1483 switch(com) {
1484 case FIOASYNC:
1485 if (*(int *)data)
1486 kq->kq_state |= KQ_ASYNC;
1487 else
1488 kq->kq_state &= ~KQ_ASYNC;
1489 error = 0;
1490 break;
1491 case FIOSETOWN:
1492 error = fsetown(*(int *)data, &kq->kq_sigio);
1493 break;
1494 default:
1495 error = ENOTTY;
1496 break;
1497 }
1498 lwkt_relpooltoken(kq);
1499 return (error);
1500 }
1501
1502 /*
1503 * MPSAFE
1504 */
1505 static int
1506 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred)
1507 {
1508 struct kqueue *kq = (struct kqueue *)fp->f_data;
1509
1510 bzero((void *)st, sizeof(*st));
1511 st->st_size = kq->kq_count;
1512 st->st_blksize = sizeof(struct kevent);
1513 st->st_mode = S_IFIFO;
1514 return (0);
1515 }
1516
1517 /*
1518 * MPSAFE
1519 */
1520 static int
1521 kqueue_close(struct file *fp)
1522 {
1523 struct kqueue *kq = (struct kqueue *)fp->f_data;
1524
1525 kqueue_terminate(kq);
1526
1527 fp->f_data = NULL;
1528 funsetown(&kq->kq_sigio);
1529
1530 kfree(kq, M_KQUEUE);
1531 return (0);
1532 }
1533
1534 static void
1535 kqueue_wakeup(struct kqueue *kq)
1536 {
1537 if (kq->kq_sleep_cnt) {
1538 u_int sleep_cnt = kq->kq_sleep_cnt;
1539
1540 kq->kq_sleep_cnt = 0;
1541 if (sleep_cnt == 1)
1542 wakeup_one(kq);
1543 else
1544 wakeup(kq);
1545 }
1546 KNOTE(&kq->kq_kqinfo.ki_note, 0);
1547 }
1548
1549 /*
1550 * Calls filterops f_attach function, acquiring mplock if filter is not
1551 * marked as FILTEROP_MPSAFE.
1552 *
1553 * Caller must be holding the related kq token
1554 */
1555 static int
1556 filter_attach(struct knote *kn)
1557 {
1558 int ret;
1559
1560 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1561 ret = kn->kn_fop->f_attach(kn);
1562 } else {
1563 get_mplock();
1564 ret = kn->kn_fop->f_attach(kn);
1565 rel_mplock();
1566 }
1567 return (ret);
1568 }
1569
1570 /*
1571 * Detach the knote and drop it, destroying the knote.
1572 *
1573 * Calls filterops f_detach function, acquiring mplock if filter is not
1574 * marked as FILTEROP_MPSAFE.
1575 *
1576 * Caller must be holding the related kq token
1577 */
1578 static void
1579 knote_detach_and_drop(struct knote *kn)
1580 {
1581 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1582 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1583 kn->kn_fop->f_detach(kn);
1584 } else {
1585 get_mplock();
1586 kn->kn_fop->f_detach(kn);
1587 rel_mplock();
1588 }
1589 knote_drop(kn);
1590 }
1591
1592 /*
1593 * Calls filterops f_event function, acquiring mplock if filter is not
1594 * marked as FILTEROP_MPSAFE.
1595 *
1596 * If the knote is in the middle of being created or deleted we cannot
1597 * safely call the filter op.
1598 *
1599 * Caller must be holding the related kq token
1600 */
1601 static int
1602 filter_event(struct knote *kn, long hint)
1603 {
1604 int ret;
1605
1606 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1607 ret = kn->kn_fop->f_event(kn, hint);
1608 } else {
1609 get_mplock();
1610 ret = kn->kn_fop->f_event(kn, hint);
1611 rel_mplock();
1612 }
1613 return (ret);
1614 }
1615
1616 /*
1617 * Walk down a list of knotes, activating them if their event has triggered.
1618 *
1619 * If we encounter any knotes which are undergoing processing we just mark
1620 * them for reprocessing and do not try to [re]activate the knote. However,
1621 * if a hint is being passed we have to wait and that makes things a bit
1622 * sticky.
1623 */
1624 void
1625 knote(struct klist *list, long hint)
1626 {
1627 struct kqueue *kq;
1628 struct knote *kn;
1629 struct knote *kntmp;
1630
1631 lwkt_getpooltoken(list);
1632 restart:
1633 SLIST_FOREACH(kn, list, kn_next) {
1634 kq = kn->kn_kq;
1635 lwkt_getpooltoken(kq);
1636
1637 /* temporary verification hack */
1638 SLIST_FOREACH(kntmp, list, kn_next) {
1639 if (kn == kntmp)
1640 break;
1641 }
1642 if (kn != kntmp || kn->kn_kq != kq) {
1643 lwkt_relpooltoken(kq);
1644 goto restart;
1645 }
1646
1647 if (kn->kn_status & KN_PROCESSING) {
1648 /*
1649 * Someone else is processing the knote, ask the
1650 * other thread to reprocess it and don't mess
1651 * with it otherwise.
1652 */
1653 if (hint == 0) {
1654 kn->kn_status |= KN_REPROCESS;
1655 lwkt_relpooltoken(kq);
1656 continue;
1657 }
1658
1659 /*
1660 * If the hint is non-zero we have to wait or risk
1661 * losing the state the caller is trying to update.
1662 *
1663 * XXX This is a real problem, certain process
1664 * and signal filters will bump kn_data for
1665 * already-processed notes more than once if
1666 * we restart the list scan. FIXME.
1667 */
1668 kn->kn_status |= KN_WAITING | KN_REPROCESS;
1669 tsleep(kn, 0, "knotec", hz);
1670 lwkt_relpooltoken(kq);
1671 goto restart;
1672 }
1673
1674 /*
1675 * Become the reprocessing master ourselves.
1676 *
1677 * If hint is non-zero running the event is mandatory
1678 * when not deleting so do it whether reprocessing is
1679 * set or not.
1680 */
1681 kn->kn_status |= KN_PROCESSING;
1682 if ((kn->kn_status & KN_DELETING) == 0) {
1683 if (filter_event(kn, hint))
1684 KNOTE_ACTIVATE(kn);
1685 }
1686 if (knote_release(kn)) {
1687 lwkt_relpooltoken(kq);
1688 goto restart;
1689 }
1690 lwkt_relpooltoken(kq);
1691 }
1692 lwkt_relpooltoken(list);
1693 }
1694
1695 /*
1696 * Insert knote at head of klist.
1697 *
1698 * This function may only be called via a filter function and thus
1699 * kq_token should already be held and marked for processing.
1700 */
1701 void
1702 knote_insert(struct klist *klist, struct knote *kn)
1703 {
1704 lwkt_getpooltoken(klist);
1705 KKASSERT(kn->kn_status & KN_PROCESSING);
1706 SLIST_INSERT_HEAD(klist, kn, kn_next);
1707 lwkt_relpooltoken(klist);
1708 }
1709
1710 /*
1711 * Remove knote from a klist
1712 *
1713 * This function may only be called via a filter function and thus
1714 * kq_token should already be held and marked for processing.
1715 */
1716 void
1717 knote_remove(struct klist *klist, struct knote *kn)
1718 {
1719 lwkt_getpooltoken(klist);
1720 KKASSERT(kn->kn_status & KN_PROCESSING);
1721 SLIST_REMOVE(klist, kn, knote, kn_next);
1722 lwkt_relpooltoken(klist);
1723 }
1724
1725 void
1726 knote_assume_knotes(struct kqinfo *src, struct kqinfo *dst,
1727 struct filterops *ops, void *hook)
1728 {
1729 struct kqueue *kq;
1730 struct knote *kn;
1731
1732 lwkt_getpooltoken(&src->ki_note);
1733 lwkt_getpooltoken(&dst->ki_note);
1734 while ((kn = SLIST_FIRST(&src->ki_note)) != NULL) {
1735 kq = kn->kn_kq;
1736 lwkt_getpooltoken(kq);
1737 if (SLIST_FIRST(&src->ki_note) != kn || kn->kn_kq != kq) {
1738 lwkt_relpooltoken(kq);
1739 continue;
1740 }
1741 if (knote_acquire(kn)) {
1742 knote_remove(&src->ki_note, kn);
1743 kn->kn_fop = ops;
1744 kn->kn_hook = hook;
1745 knote_insert(&dst->ki_note, kn);
1746 knote_release(kn);
1747 /* kn may be invalid now */
1748 }
1749 lwkt_relpooltoken(kq);
1750 }
1751 lwkt_relpooltoken(&dst->ki_note);
1752 lwkt_relpooltoken(&src->ki_note);
1753 }
1754
1755 /*
1756 * Remove all knotes referencing a specified fd
1757 */
1758 void
1759 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd)
1760 {
1761 struct kqueue *kq;
1762 struct knote *kn;
1763 struct knote *kntmp;
1764
1765 lwkt_getpooltoken(&fp->f_klist);
1766 restart:
1767 SLIST_FOREACH(kn, &fp->f_klist, kn_link) {
1768 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) {
1769 kq = kn->kn_kq;
1770 lwkt_getpooltoken(kq);
1771
1772 /* temporary verification hack */
1773 SLIST_FOREACH(kntmp, &fp->f_klist, kn_link) {
1774 if (kn == kntmp)
1775 break;
1776 }
1777 if (kn != kntmp || kn->kn_kq->kq_fdp != fdp ||
1778 kn->kn_id != fd || kn->kn_kq != kq) {
1779 lwkt_relpooltoken(kq);
1780 goto restart;
1781 }
1782 if (knote_acquire(kn))
1783 knote_detach_and_drop(kn);
1784 lwkt_relpooltoken(kq);
1785 goto restart;
1786 }
1787 }
1788 lwkt_relpooltoken(&fp->f_klist);
1789 }
1790
1791 /*
1792 * Low level attach function.
1793 *
1794 * The knote should already be marked for processing.
1795 * Caller must hold the related kq token.
1796 */
1797 static void
1798 knote_attach(struct knote *kn)
1799 {
1800 struct klist *list;
1801 struct kqueue *kq = kn->kn_kq;
1802
1803 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1804 KKASSERT(kn->kn_fp);
1805 list = &kn->kn_fp->f_klist;
1806 } else {
1807 if (kq->kq_knhashmask == 0)
1808 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
1809 &kq->kq_knhashmask);
1810 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1811 }
1812 lwkt_getpooltoken(list);
1813 SLIST_INSERT_HEAD(list, kn, kn_link);
1814 lwkt_relpooltoken(list);
1815 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink);
1816 }
1817
1818 /*
1819 * Low level drop function.
1820 *
1821 * The knote should already be marked for processing.
1822 * Caller must hold the related kq token.
1823 */
1824 static void
1825 knote_drop(struct knote *kn)
1826 {
1827 struct kqueue *kq;
1828 struct klist *list;
1829
1830 kq = kn->kn_kq;
1831
1832 if (kn->kn_fop->f_flags & FILTEROP_ISFD)
1833 list = &kn->kn_fp->f_klist;
1834 else
1835 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1836
1837 lwkt_getpooltoken(list);
1838 SLIST_REMOVE(list, kn, knote, kn_link);
1839 lwkt_relpooltoken(list);
1840 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink);
1841 if (kn->kn_status & KN_QUEUED)
1842 knote_dequeue(kn);
1843 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1844 fdrop(kn->kn_fp);
1845 kn->kn_fp = NULL;
1846 }
1847 knote_free(kn);
1848 }
1849
1850 /*
1851 * Low level enqueue function.
1852 *
1853 * The knote should already be marked for processing.
1854 * Caller must be holding the kq token
1855 */
1856 static void
1857 knote_enqueue(struct knote *kn)
1858 {
1859 struct kqueue *kq = kn->kn_kq;
1860
1861 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
1862 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1863 kn->kn_status |= KN_QUEUED;
1864 ++kq->kq_count;
1865
1866 /*
1867 * Send SIGIO on request (typically set up as a mailbox signal)
1868 */
1869 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1)
1870 pgsigio(kq->kq_sigio, SIGIO, 0);
1871
1872 kqueue_wakeup(kq);
1873 }
1874
1875 /*
1876 * Low level dequeue function.
1877 *
1878 * The knote should already be marked for processing.
1879 * Caller must be holding the kq token
1880 */
1881 static void
1882 knote_dequeue(struct knote *kn)
1883 {
1884 struct kqueue *kq = kn->kn_kq;
1885
1886 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
1887 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
1888 kn->kn_status &= ~KN_QUEUED;
1889 kq->kq_count--;
1890 }
1891
1892 static struct knote *
1893 knote_alloc(void)
1894 {
1895 return kmalloc(sizeof(struct knote), M_KQUEUE, M_WAITOK);
1896 }
1897
1898 static void
1899 knote_free(struct knote *kn)
1900 {
1901 struct knote_cache_list *cache_list;
1902
1903 cache_list = &knote_cache_lists[mycpuid];
1904 if (cache_list->knote_cache_cnt < KNOTE_CACHE_MAX) {
1905 crit_enter();
1906 SLIST_INSERT_HEAD(&cache_list->knote_cache, kn, kn_link);
1907 cache_list->knote_cache_cnt++;
1908 crit_exit();
1909 return;
1910 }
1911 kfree(kn, M_KQUEUE);
1912 }
1913
1914 struct sleepinfo {
1915 void *ident;
1916 int timedout;
1917 };
1918
1919 static void
1920 precise_sleep_intr(systimer_t info, int in_ipi, struct intrframe *frame)
1921 {
1922 struct sleepinfo *si;
1923
1924 si = info->data;
1925 si->timedout = 1;
1926 wakeup(si->ident);
1927 }
1928
1929 static int
1930 precise_sleep(void *ident, int flags, const char *wmesg, int us)
1931 {
1932 struct systimer info;
1933 struct sleepinfo si = {
1934 .ident = ident,
1935 .timedout = 0,
1936 };
1937 int r;
1938
1939 tsleep_interlock(ident, flags);
1940 systimer_init_oneshot(&info, precise_sleep_intr, &si,
1941 us == 0 ? 1 : us);
1942 r = tsleep(ident, flags | PINTERLOCKED, wmesg, 0);
1943 systimer_del(&info);
1944 if (si.timedout)
1945 r = EWOULDBLOCK;
1946
1947 return r;
1948 }
DragonFly BSD