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nrelease - fix/improve livecd
[dragonfly.git] / sys / kern / kern_event.c
blob29dea9f38ff4671cc8494b95a37adf7af3cb2848
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/sysmsg.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 static MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
63
64 struct kevent_copyin_args {
65 const struct kevent_args *ka;
66 struct kevent *eventlist;
67 const struct kevent *changelist;
68 int pchanges;
69 };
70
71 #define KNOTE_CACHE_MAX 64
72
73 struct knote_cache_list {
74 struct klist knote_cache;
75 int knote_cache_cnt;
76 } __cachealign;
77
78 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
79 struct knote *marker, int closedcounter, int flags);
80 static int kqueue_read(struct file *fp, struct uio *uio,
81 struct ucred *cred, int flags);
82 static int kqueue_write(struct file *fp, struct uio *uio,
83 struct ucred *cred, int flags);
84 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
85 struct ucred *cred, struct sysmsg *msg);
86 static int kqueue_kqfilter(struct file *fp, struct knote *kn);
87 static int kqueue_stat(struct file *fp, struct stat *st,
88 struct ucred *cred);
89 static int kqueue_close(struct file *fp);
90 static void kqueue_wakeup(struct kqueue *kq);
91 static int filter_attach(struct knote *kn);
92 static int filter_event(struct knote *kn, long hint);
93
94 /*
95 * MPSAFE
96 */
97 static struct fileops kqueueops = {
98 .fo_read = kqueue_read,
99 .fo_write = kqueue_write,
100 .fo_ioctl = kqueue_ioctl,
101 .fo_kqfilter = kqueue_kqfilter,
102 .fo_stat = kqueue_stat,
103 .fo_close = kqueue_close,
104 .fo_shutdown = nofo_shutdown
105 };
106
107 static void knote_attach(struct knote *kn);
108 static void knote_drop(struct knote *kn);
109 static void knote_detach_and_drop(struct knote *kn);
110 static void knote_enqueue(struct knote *kn);
111 static void knote_dequeue(struct knote *kn);
112 static struct knote *knote_alloc(void);
113 static void knote_free(struct knote *kn);
114
115 static void precise_sleep_intr(systimer_t info, int in_ipi,
116 struct intrframe *frame);
117 static int precise_sleep(void *ident, int flags, const char *wmesg,
118 int us);
119
120 static void filt_kqdetach(struct knote *kn);
121 static int filt_kqueue(struct knote *kn, long hint);
122 static int filt_procattach(struct knote *kn);
123 static void filt_procdetach(struct knote *kn);
124 static int filt_proc(struct knote *kn, long hint);
125 static int filt_fileattach(struct knote *kn);
126 static void filt_timerexpire(void *knx);
127 static int filt_timerattach(struct knote *kn);
128 static void filt_timerdetach(struct knote *kn);
129 static int filt_timer(struct knote *kn, long hint);
130 static int filt_userattach(struct knote *kn);
131 static void filt_userdetach(struct knote *kn);
132 static int filt_user(struct knote *kn, long hint);
133 static void filt_usertouch(struct knote *kn, struct kevent *kev,
134 u_long type);
135 static int filt_fsattach(struct knote *kn);
136 static void filt_fsdetach(struct knote *kn);
137 static int filt_fs(struct knote *kn, long hint);
138
139 static struct filterops file_filtops =
140 { FILTEROP_ISFD | FILTEROP_MPSAFE, filt_fileattach, NULL, NULL };
141 static struct filterops kqread_filtops =
142 { FILTEROP_ISFD | FILTEROP_MPSAFE, NULL, filt_kqdetach, filt_kqueue };
143 static struct filterops proc_filtops =
144 { FILTEROP_MPSAFE, filt_procattach, filt_procdetach, filt_proc };
145 static struct filterops timer_filtops =
146 { FILTEROP_MPSAFE, filt_timerattach, filt_timerdetach, filt_timer };
147 static struct filterops user_filtops =
148 { FILTEROP_MPSAFE, filt_userattach, filt_userdetach, filt_user };
149 static struct filterops fs_filtops =
150 { FILTEROP_MPSAFE, filt_fsattach, filt_fsdetach, filt_fs };
151
152 static int kq_ncallouts = 0;
153 static int kq_calloutmax = 65536;
154 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
155 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
156 static int kq_checkloop = 1000000;
157 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW,
158 &kq_checkloop, 0, "Maximum number of loops for kqueue scan");
159 static int kq_sleep_threshold = 20000;
160 SYSCTL_INT(_kern, OID_AUTO, kq_sleep_threshold, CTLFLAG_RW,
161 &kq_sleep_threshold, 0, "Minimum sleep duration without busy-looping");
162
163 #define KNOTE_ACTIVATE(kn) do { \
164 kn->kn_status |= KN_ACTIVE; \
165 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \
166 knote_enqueue(kn); \
167 } while(0)
168
169 #define KN_HASHSIZE 64 /* XXX should be tunable */
170 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask))
171
172 extern struct filterops aio_filtops;
173 extern struct filterops sig_filtops;
174
175 /*
176 * Table for for all system-defined filters.
177 */
178 static struct filterops *sysfilt_ops[] = {
179 &file_filtops, /* EVFILT_READ */
180 &file_filtops, /* EVFILT_WRITE */
181 &aio_filtops, /* EVFILT_AIO */
182 &file_filtops, /* EVFILT_VNODE */
183 &proc_filtops, /* EVFILT_PROC */
184 &sig_filtops, /* EVFILT_SIGNAL */
185 &timer_filtops, /* EVFILT_TIMER */
186 &file_filtops, /* EVFILT_EXCEPT */
187 &user_filtops, /* EVFILT_USER */
188 &fs_filtops, /* EVFILT_FS */
189 };
190
191 static struct knote_cache_list knote_cache_lists[MAXCPU];
192
193 /*
194 * Acquire a knote, return non-zero on success, 0 on failure.
195 *
196 * If we cannot acquire the knote we sleep and return 0. The knote
197 * may be stale on return in this case and the caller must restart
198 * whatever loop they are in.
199 *
200 * Related kq token must be held.
201 */
202 static __inline int
203 knote_acquire(struct knote *kn)
204 {
205 if (kn->kn_status & KN_PROCESSING) {
206 kn->kn_status |= KN_WAITING | KN_REPROCESS;
207 tsleep(kn, 0, "kqepts", hz);
208 /* knote may be stale now */
209 return(0);
210 }
211 kn->kn_status |= KN_PROCESSING;
212 return(1);
213 }
214
215 /*
216 * Release an acquired knote, clearing KN_PROCESSING and handling any
217 * KN_REPROCESS events.
218 *
219 * Caller must be holding the related kq token
220 *
221 * Non-zero is returned if the knote is destroyed or detached.
222 */
223 static __inline int
224 knote_release(struct knote *kn)
225 {
226 int ret;
227
228 while (kn->kn_status & KN_REPROCESS) {
229 kn->kn_status &= ~KN_REPROCESS;
230 if (kn->kn_status & KN_WAITING) {
231 kn->kn_status &= ~KN_WAITING;
232 wakeup(kn);
233 }
234 if (kn->kn_status & KN_DELETING) {
235 knote_detach_and_drop(kn);
236 return(1);
237 /* NOT REACHED */
238 }
239 if (filter_event(kn, 0))
240 KNOTE_ACTIVATE(kn);
241 }
242 if (kn->kn_status & KN_DETACHED)
243 ret = 1;
244 else
245 ret = 0;
246 kn->kn_status &= ~KN_PROCESSING;
247 /* kn should not be accessed anymore */
248 return ret;
249 }
250
251 static int
252 filt_fileattach(struct knote *kn)
253 {
254 return (fo_kqfilter(kn->kn_fp, kn));
255 }
256
257 /*
258 * MPSAFE
259 */
260 static int
261 kqueue_kqfilter(struct file *fp, struct knote *kn)
262 {
263 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
264
265 if (kn->kn_filter != EVFILT_READ)
266 return (EOPNOTSUPP);
267
268 kn->kn_fop = &kqread_filtops;
269 knote_insert(&kq->kq_kqinfo.ki_note, kn);
270 return (0);
271 }
272
273 static void
274 filt_kqdetach(struct knote *kn)
275 {
276 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
277
278 knote_remove(&kq->kq_kqinfo.ki_note, kn);
279 }
280
281 /*ARGSUSED*/
282 static int
283 filt_kqueue(struct knote *kn, long hint)
284 {
285 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
286
287 kn->kn_data = kq->kq_count;
288 return (kn->kn_data > 0);
289 }
290
291 static int
292 filt_procattach(struct knote *kn)
293 {
294 struct proc *p;
295 int immediate;
296
297 immediate = 0;
298 p = pfind(kn->kn_id);
299 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
300 p = zpfind(kn->kn_id);
301 immediate = 1;
302 }
303 if (p == NULL) {
304 return (ESRCH);
305 }
306 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) {
307 if (p)
308 PRELE(p);
309 return (EACCES);
310 }
311
312 lwkt_gettoken(&p->p_token);
313 kn->kn_ptr.p_proc = p;
314 kn->kn_flags |= EV_CLEAR; /* automatically set */
315
316 /*
317 * internal flag indicating registration done by kernel
318 */
319 if (kn->kn_flags & EV_FLAG1) {
320 kn->kn_data = kn->kn_sdata; /* ppid */
321 kn->kn_fflags = NOTE_CHILD;
322 kn->kn_flags &= ~EV_FLAG1;
323 }
324
325 knote_insert(&p->p_klist, kn);
326
327 /*
328 * Immediately activate any exit notes if the target process is a
329 * zombie. This is necessary to handle the case where the target
330 * process, e.g. a child, dies before the kevent is negistered.
331 */
332 if (immediate && filt_proc(kn, NOTE_EXIT))
333 KNOTE_ACTIVATE(kn);
334 lwkt_reltoken(&p->p_token);
335 PRELE(p);
336
337 return (0);
338 }
339
340 /*
341 * The knote may be attached to a different process, which may exit,
342 * leaving nothing for the knote to be attached to. So when the process
343 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
344 * it will be deleted when read out. However, as part of the knote deletion,
345 * this routine is called, so a check is needed to avoid actually performing
346 * a detach, because the original process does not exist any more.
347 */
348 static void
349 filt_procdetach(struct knote *kn)
350 {
351 struct proc *p;
352
353 if (kn->kn_status & KN_DETACHED)
354 return;
355 p = kn->kn_ptr.p_proc;
356 knote_remove(&p->p_klist, kn);
357 }
358
359 static int
360 filt_proc(struct knote *kn, long hint)
361 {
362 u_int event;
363
364 /*
365 * mask off extra data
366 */
367 event = (u_int)hint & NOTE_PCTRLMASK;
368
369 /*
370 * if the user is interested in this event, record it.
371 */
372 if (kn->kn_sfflags & event)
373 kn->kn_fflags |= event;
374
375 /*
376 * Process is gone, so flag the event as finished. Detach the
377 * knote from the process now because the process will be poof,
378 * gone later on.
379 */
380 if (event == NOTE_EXIT) {
381 struct proc *p = kn->kn_ptr.p_proc;
382 if ((kn->kn_status & KN_DETACHED) == 0) {
383 PHOLD(p);
384 knote_remove(&p->p_klist, kn);
385 kn->kn_status |= KN_DETACHED;
386 kn->kn_data = p->p_xstat;
387 kn->kn_ptr.p_proc = NULL;
388 PRELE(p);
389 }
390 kn->kn_flags |= (EV_EOF | EV_NODATA | EV_ONESHOT);
391 return (1);
392 }
393
394 /*
395 * process forked, and user wants to track the new process,
396 * so attach a new knote to it, and immediately report an
397 * event with the parent's pid.
398 */
399 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) {
400 struct kevent kev;
401 int error;
402 int n;
403
404 /*
405 * register knote with new process.
406 */
407 kev.ident = hint & NOTE_PDATAMASK; /* pid */
408 kev.filter = kn->kn_filter;
409 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
410 kev.fflags = kn->kn_sfflags;
411 kev.data = kn->kn_id; /* parent */
412 kev.udata = kn->kn_kevent.udata; /* preserve udata */
413 n = 1;
414 error = kqueue_register(kn->kn_kq, &kev, &n, 0);
415 if (error)
416 kn->kn_fflags |= NOTE_TRACKERR;
417 }
418
419 return (kn->kn_fflags != 0);
420 }
421
422 static void
423 filt_timerreset(struct knote *kn)
424 {
425 struct callout *calloutp;
426 struct timeval tv;
427 int tticks;
428
429 tv.tv_sec = kn->kn_sdata / 1000;
430 tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
431 tticks = tvtohz_high(&tv);
432 calloutp = (struct callout *)kn->kn_hook;
433 callout_reset(calloutp, tticks, filt_timerexpire, kn);
434 }
435
436 /*
437 * The callout interlocks with callout_stop() but can still
438 * race a deletion so if KN_DELETING is set we just don't touch
439 * the knote.
440 */
441 static void
442 filt_timerexpire(void *knx)
443 {
444 struct knote *kn = knx;
445 struct kqueue *kq = kn->kn_kq;
446
447 lwkt_getpooltoken(kq);
448
449 /*
450 * Open knote_acquire(), since we can't sleep in callout,
451 * however, we do need to record this expiration.
452 */
453 kn->kn_data++;
454 if (kn->kn_status & KN_PROCESSING) {
455 kn->kn_status |= KN_REPROCESS;
456 if ((kn->kn_status & KN_DELETING) == 0 &&
457 (kn->kn_flags & EV_ONESHOT) == 0)
458 filt_timerreset(kn);
459 lwkt_relpooltoken(kq);
460 return;
461 }
462 KASSERT((kn->kn_status & KN_DELETING) == 0,
463 ("acquire a deleting knote %#x", kn->kn_status));
464 kn->kn_status |= KN_PROCESSING;
465
466 KNOTE_ACTIVATE(kn);
467 if ((kn->kn_flags & EV_ONESHOT) == 0)
468 filt_timerreset(kn);
469
470 knote_release(kn);
471
472 lwkt_relpooltoken(kq);
473 }
474
475 /*
476 * data contains amount of time to sleep, in milliseconds
477 */
478 static int
479 filt_timerattach(struct knote *kn)
480 {
481 struct callout *calloutp;
482 int prev_ncallouts;
483
484 prev_ncallouts = atomic_fetchadd_int(&kq_ncallouts, 1);
485 if (prev_ncallouts >= kq_calloutmax) {
486 atomic_subtract_int(&kq_ncallouts, 1);
487 kn->kn_hook = NULL;
488 return (ENOMEM);
489 }
490
491 kn->kn_flags |= EV_CLEAR; /* automatically set */
492 calloutp = kmalloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
493 callout_init_mp(calloutp);
494 kn->kn_hook = (caddr_t)calloutp;
495
496 filt_timerreset(kn);
497 return (0);
498 }
499
500 /*
501 * This function is called with the knote flagged locked but it is
502 * still possible to race a callout event due to the callback blocking.
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 void
683 kqueue_init(struct kqueue *kq, struct filedesc *fdp)
684 {
685 bzero(kq, sizeof(*kq));
686 TAILQ_INIT(&kq->kq_knpend);
687 TAILQ_INIT(&kq->kq_knlist);
688 kq->kq_fdp = fdp;
689 SLIST_INIT(&kq->kq_kqinfo.ki_note);
690 }
691
692 /*
693 * Terminate a kqueue. Freeing the actual kq itself is left up to the
694 * caller (it might be embedded in a lwp so we don't do it here).
695 *
696 * The kq's knlist must be completely eradicated so block on any
697 * processing races.
698 */
699 void
700 kqueue_terminate(struct kqueue *kq)
701 {
702 struct knote *kn;
703
704 lwkt_getpooltoken(kq);
705 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL) {
706 if (knote_acquire(kn))
707 knote_detach_and_drop(kn);
708 }
709 lwkt_relpooltoken(kq);
710
711 if (kq->kq_knhash) {
712 hashdestroy(kq->kq_knhash, M_KQUEUE, kq->kq_knhashmask);
713 kq->kq_knhash = NULL;
714 kq->kq_knhashmask = 0;
715 }
716 }
717
718 /*
719 * MPSAFE
720 */
721 int
722 sys_kqueue(struct sysmsg *sysmsg, const struct kqueue_args *uap)
723 {
724 struct thread *td = curthread;
725 struct kqueue *kq;
726 struct file *fp;
727 int fd, error;
728
729 error = falloc(td->td_lwp, &fp, &fd);
730 if (error)
731 return (error);
732 fp->f_flag = FREAD | FWRITE;
733 fp->f_type = DTYPE_KQUEUE;
734 fp->f_ops = &kqueueops;
735
736 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO);
737 kqueue_init(kq, td->td_proc->p_fd);
738 fp->f_data = kq;
739
740 fsetfd(kq->kq_fdp, fp, fd);
741 sysmsg->sysmsg_result = fd;
742 fdrop(fp);
743 return (0);
744 }
745
746 /*
747 * Copy 'count' items into the destination list pointed to by uap->eventlist.
748 */
749 static int
750 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res)
751 {
752 struct kevent_copyin_args *kap;
753 int error;
754
755 kap = (struct kevent_copyin_args *)arg;
756
757 error = copyout(kevp, kap->eventlist, count * sizeof(*kevp));
758 if (error == 0) {
759 kap->eventlist += count;
760 *res += count;
761 } else {
762 *res = -1;
763 }
764
765 return (error);
766 }
767
768 /*
769 * Copy at most 'max' items from the list pointed to by kap->changelist,
770 * return number of items in 'events'.
771 */
772 static int
773 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events)
774 {
775 struct kevent_copyin_args *kap;
776 int error, count;
777
778 kap = (struct kevent_copyin_args *)arg;
779
780 count = min(kap->ka->nchanges - kap->pchanges, max);
781 error = copyin(kap->changelist, kevp, count * sizeof *kevp);
782 if (error == 0) {
783 kap->changelist += count;
784 kap->pchanges += count;
785 *events = count;
786 }
787
788 return (error);
789 }
790
791 /*
792 * MPSAFE
793 */
794 int
795 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap,
796 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn,
797 struct timespec *tsp_in, int flags)
798 {
799 struct kevent *kevp;
800 struct timespec *tsp, ats;
801 int i, n, total, error, nerrors = 0;
802 int gobbled;
803 int lres;
804 int limit = kq_checkloop;
805 int closedcounter;
806 struct kevent kev[KQ_NEVENTS];
807 struct knote marker;
808 struct lwkt_token *tok;
809
810 if (tsp_in == NULL || tsp_in->tv_sec || tsp_in->tv_nsec)
811 atomic_set_int(&curthread->td_mpflags, TDF_MP_BATCH_DEMARC);
812
813 tsp = tsp_in;
814 *res = 0;
815
816 closedcounter = kq->kq_fdp->fd_closedcounter;
817
818 for (;;) {
819 n = 0;
820 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n);
821 if (error)
822 return error;
823 if (n == 0)
824 break;
825 for (i = 0; i < n; ++i)
826 kev[i].flags &= ~EV_SYSFLAGS;
827 for (i = 0; i < n; ++i) {
828 gobbled = n - i;
829
830 error = kqueue_register(kq, &kev[i], &gobbled, flags);
831 i += gobbled - 1;
832 kevp = &kev[i];
833
834 /*
835 * If a registration returns an error we
836 * immediately post the error. The kevent()
837 * call itself will fail with the error if
838 * no space is available for posting.
839 *
840 * Such errors normally bypass the timeout/blocking
841 * code. However, if the copyoutfn function refuses
842 * to post the error (see sys_poll()), then we
843 * ignore it too.
844 */
845 if (error || (kevp->flags & EV_RECEIPT)) {
846 kevp->flags = EV_ERROR;
847 kevp->data = error;
848 lres = *res;
849 kevent_copyoutfn(uap, kevp, 1, res);
850 if (*res < 0) {
851 return error;
852 } else if (lres != *res) {
853 nevents--;
854 nerrors++;
855 }
856 }
857 }
858 }
859 if (nerrors)
860 return 0;
861
862 /*
863 * Acquire/wait for events - setup timeout
864 *
865 * If no timeout specified clean up the run path by clearing the
866 * PRECISE flag.
867 */
868 if (tsp != NULL) {
869 if (tsp->tv_sec || tsp->tv_nsec) {
870 getnanouptime(&ats);
871 timespecadd(tsp, &ats, tsp); /* tsp = target time */
872 }
873 } else {
874 flags &= ~KEVENT_TIMEOUT_PRECISE;
875 }
876
877 /*
878 * Loop as required.
879 *
880 * Collect as many events as we can. Sleeping on successive
881 * loops is disabled if copyoutfn has incremented (*res).
882 *
883 * The loop stops if an error occurs, all events have been
884 * scanned (the marker has been reached), or fewer than the
885 * maximum number of events is found.
886 *
887 * The copyoutfn function does not have to increment (*res) in
888 * order for the loop to continue.
889 *
890 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents.
891 */
892 total = 0;
893 error = 0;
894 marker.kn_filter = EVFILT_MARKER;
895 marker.kn_status = KN_PROCESSING;
896
897 tok = lwkt_token_pool_lookup(kq);
898 flags = (flags & ~KEVENT_SCAN_MASK) | KEVENT_SCAN_INSERT_MARKER;
899
900 while ((n = nevents - total) > 0) {
901 if (n > KQ_NEVENTS)
902 n = KQ_NEVENTS;
903
904 /*
905 * Process all received events
906 * Account for all non-spurious events in our total
907 */
908 i = kqueue_scan(kq, kev, n, &marker, closedcounter, flags);
909 flags = (flags & ~KEVENT_SCAN_MASK) | KEVENT_SCAN_KEEP_MARKER;
910 if (i) {
911 lres = *res;
912 error = kevent_copyoutfn(uap, kev, i, res);
913 total += *res - lres;
914 if (error)
915 break;
916 }
917 if (limit && --limit == 0)
918 panic("kqueue: checkloop failed i=%d", i);
919
920 /*
921 * Normally when fewer events are returned than requested
922 * we can stop. However, if only spurious events were
923 * collected the copyout will not bump (*res) and we have
924 * to continue.
925 */
926 if (i < n && *res)
927 break;
928
929 /*
930 * If no events were recorded (no events happened or the events
931 * that did happen were all spurious), block until an event
932 * occurs or the timeout occurs and reload the marker.
933 *
934 * If we saturated n (i == n) loop up without sleeping to
935 * continue processing the list.
936 */
937 if (i != n && kq->kq_count == 0 && *res == 0) {
938 int timeout;
939 int ustimeout;
940
941 if (tsp == NULL) {
942 timeout = 0;
943 ustimeout = 0;
944 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) {
945 error = EWOULDBLOCK;
946 break;
947 } else {
948 struct timespec atx = *tsp;
949
950 getnanouptime(&ats);
951 timespecsub(&atx, &ats, &atx);
952 if (atx.tv_sec < 0 ||
953 (atx.tv_sec == 0 && atx.tv_nsec <= 0)) {
954 error = EWOULDBLOCK;
955 break;
956 }
957 if (flags & KEVENT_TIMEOUT_PRECISE) {
958 if (atx.tv_sec == 0 &&
959 atx.tv_nsec < kq_sleep_threshold) {
960 ustimeout = kq_sleep_threshold /
961 1000;
962 } else if (atx.tv_sec < 60) {
963 ustimeout =
964 atx.tv_sec * 1000000 +
965 atx.tv_nsec / 1000;
966 } else {
967 ustimeout = 60 * 1000000;
968 }
969 if (ustimeout == 0)
970 ustimeout = 1;
971 timeout = 0;
972 } else if (atx.tv_sec > 60 * 60) {
973 timeout = 60 * 60 * hz;
974 ustimeout = 0;
975 } else {
976 timeout = tstohz_high(&atx);
977 ustimeout = 0;
978 }
979 }
980
981 lwkt_gettoken(tok);
982 if (kq->kq_count == 0) {
983 kq->kq_sleep_cnt++;
984 if (__predict_false(kq->kq_sleep_cnt == 0)) {
985 /*
986 * Guard against possible wrapping. And
987 * set it to 2, so that kqueue_wakeup()
988 * can wake everyone up.
989 */
990 kq->kq_sleep_cnt = 2;
991 }
992 if (flags & KEVENT_TIMEOUT_PRECISE) {
993 error = precise_sleep(kq, PCATCH,
994 "kqread", ustimeout);
995 } else {
996 error = tsleep(kq, PCATCH,
997 "kqread", timeout);
998 }
999
1000 /* don't restart after signals... */
1001 if (error == ERESTART)
1002 error = EINTR;
1003 if (error == EWOULDBLOCK)
1004 error = 0;
1005 if (error) {
1006 lwkt_reltoken(tok);
1007 break;
1008 }
1009 flags = (flags & ~KEVENT_SCAN_MASK) |
1010 KEVENT_SCAN_RELOAD_MARKER;
1011 }
1012 lwkt_reltoken(tok);
1013 }
1014
1015 /*
1016 * Deal with an edge case where spurious events can cause
1017 * a loop to occur without moving the marker. This can
1018 * prevent kqueue_scan() from picking up new events which
1019 * race us. We must be sure to move the marker for this
1020 * case.
1021 *
1022 * NOTE: We do not want to move the marker if events
1023 * were scanned because normal kqueue operations
1024 * may reactivate events. Moving the marker in
1025 * that case could result in duplicates for the
1026 * same event.
1027 */
1028 if (i == 0) {
1029 flags = (flags & ~KEVENT_SCAN_MASK) |
1030 KEVENT_SCAN_RELOAD_MARKER;
1031 }
1032 }
1033
1034 /*
1035 * Remove the marker
1036 */
1037 if ((flags & KEVENT_SCAN_INSERT_MARKER) == 0) {
1038 lwkt_gettoken(tok);
1039 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
1040 lwkt_reltoken(tok);
1041 }
1042
1043 /* Timeouts do not return EWOULDBLOCK. */
1044 if (error == EWOULDBLOCK)
1045 error = 0;
1046 return error;
1047 }
1048
1049 /*
1050 * MPALMOSTSAFE
1051 */
1052 int
1053 sys_kevent(struct sysmsg *sysmsg, const struct kevent_args *uap)
1054 {
1055 struct thread *td = curthread;
1056 struct timespec ts, *tsp;
1057 struct kqueue *kq;
1058 struct file *fp = NULL;
1059 struct kevent_copyin_args *kap, ka;
1060 int error;
1061
1062 if (uap->timeout) {
1063 error = copyin(uap->timeout, &ts, sizeof(ts));
1064 if (error)
1065 return (error);
1066 tsp = &ts;
1067 } else {
1068 tsp = NULL;
1069 }
1070 fp = holdfp(td, uap->fd, -1);
1071 if (fp == NULL)
1072 return (EBADF);
1073 if (fp->f_type != DTYPE_KQUEUE) {
1074 fdrop(fp);
1075 return (EBADF);
1076 }
1077
1078 kq = (struct kqueue *)fp->f_data;
1079
1080 kap = &ka;
1081 kap->ka = uap;
1082 kap->pchanges = 0;
1083 kap->eventlist = uap->eventlist;
1084 kap->changelist = uap->changelist;
1085
1086 error = kern_kevent(kq, uap->nevents, &sysmsg->sysmsg_result, kap,
1087 kevent_copyin, kevent_copyout, tsp, 0);
1088
1089 dropfp(td, uap->fd, fp);
1090
1091 return (error);
1092 }
1093
1094 /*
1095 * Efficiently load multiple file pointers. This significantly reduces
1096 * threaded overhead. When doing simple polling we can depend on the
1097 * per-thread (fd,fp) cache. With more descriptors, we batch.
1098 */
1099 static
1100 void
1101 floadkevfps(thread_t td, struct filedesc *fdp, struct kevent *kev,
1102 struct file **fp, int climit)
1103 {
1104 struct filterops *fops;
1105 int tdcache;
1106
1107 if (climit <= 2 && td->td_proc && td->td_proc->p_fd == fdp) {
1108 tdcache = 1;
1109 } else {
1110 tdcache = 0;
1111 spin_lock_shared(&fdp->fd_spin);
1112 }
1113
1114 while (climit) {
1115 *fp = NULL;
1116 if (kev->filter < 0 &&
1117 kev->filter + EVFILT_SYSCOUNT >= 0) {
1118 fops = sysfilt_ops[~kev->filter];
1119 if (fops->f_flags & FILTEROP_ISFD) {
1120 if (tdcache) {
1121 *fp = holdfp(td, kev->ident, -1);
1122 } else {
1123 *fp = holdfp_fdp_locked(fdp,
1124 kev->ident, -1);
1125 }
1126 }
1127 }
1128 --climit;
1129 ++fp;
1130 ++kev;
1131 }
1132 if (tdcache == 0)
1133 spin_unlock_shared(&fdp->fd_spin);
1134 }
1135
1136 /*
1137 * Register up to *countp kev's. Always registers at least 1.
1138 *
1139 * The number registered is returned in *countp.
1140 *
1141 * If an error occurs or a kev is flagged EV_RECEIPT, it is
1142 * processed and included in *countp, and processing then
1143 * stops.
1144 *
1145 * If flags contains KEVENT_UNIQUE_NOTES, kev->data contains an identifier
1146 * to further distinguish knotes which might otherwise have the same kq,
1147 * ident, and filter (used by *poll() because multiple pfds are allowed to
1148 * reference the same descriptor and implied kq filter). kev->data is
1149 * implied to be zero for event processing when this flag is set.
1150 */
1151 int
1152 kqueue_register(struct kqueue *kq, struct kevent *kev, int *countp, int flags)
1153 {
1154 struct filedesc *fdp = kq->kq_fdp;
1155 struct klist *list = NULL;
1156 struct filterops *fops;
1157 struct file *fp[KQ_NEVENTS];
1158 struct knote *kn = NULL;
1159 struct thread *td;
1160 int error;
1161 int count;
1162 int climit;
1163 int closedcounter;
1164 int uniqifier = 0;
1165 struct knote_cache_list *cache_list;
1166
1167 td = curthread;
1168 climit = *countp;
1169 if (climit > KQ_NEVENTS)
1170 climit = KQ_NEVENTS;
1171 closedcounter = fdp->fd_closedcounter;
1172 floadkevfps(td, fdp, kev, fp, climit);
1173
1174 lwkt_getpooltoken(kq);
1175 count = 0;
1176 error = 0;
1177
1178 /*
1179 * To avoid races, only one thread can register events on this
1180 * kqueue at a time.
1181 */
1182 while (__predict_false(kq->kq_regtd != NULL && kq->kq_regtd != td)) {
1183 kq->kq_state |= KQ_REGWAIT;
1184 tsleep(&kq->kq_regtd, 0, "kqreg", 0);
1185 }
1186 if (__predict_false(kq->kq_regtd != NULL)) {
1187 /* Recursive calling of kqueue_register() */
1188 td = NULL;
1189 } else {
1190 /* Owner of the kq_regtd, i.e. td != NULL */
1191 kq->kq_regtd = td;
1192 }
1193
1194 loop:
1195 /*
1196 * knote uniqifiers are used by *poll() because there may be
1197 * multiple pfd[] entries for the same descriptor and filter.
1198 * The unique id is stored in kev->data and kev->data for the
1199 * kevent is implied to be zero.
1200 */
1201 if (flags & KEVENT_UNIQUE_NOTES) {
1202 uniqifier = kev->data;
1203 kev->data = 0;
1204 }
1205
1206 if (kev->filter < 0) {
1207 if (kev->filter + EVFILT_SYSCOUNT < 0) {
1208 error = EINVAL;
1209 ++count;
1210 goto done;
1211 }
1212 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */
1213 } else {
1214 /*
1215 * XXX
1216 * filter attach routine is responsible for insuring that
1217 * the identifier can be attached to it.
1218 */
1219 error = EINVAL;
1220 ++count;
1221 goto done;
1222 }
1223
1224 if (fops->f_flags & FILTEROP_ISFD) {
1225 /* validate descriptor */
1226 if (fp[count] == NULL) {
1227 error = EBADF;
1228 ++count;
1229 goto done;
1230 }
1231 }
1232
1233 cache_list = &knote_cache_lists[mycpuid];
1234 if (SLIST_EMPTY(&cache_list->knote_cache)) {
1235 struct knote *new_kn;
1236
1237 new_kn = knote_alloc();
1238 crit_enter();
1239 SLIST_INSERT_HEAD(&cache_list->knote_cache, new_kn, kn_link);
1240 cache_list->knote_cache_cnt++;
1241 crit_exit();
1242 }
1243
1244 if (fp[count] != NULL) {
1245 list = &fp[count]->f_klist;
1246 } else if (kq->kq_knhashmask) {
1247 list = &kq->kq_knhash[
1248 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
1249 }
1250 if (list != NULL) {
1251 lwkt_getpooltoken(list);
1252 again:
1253 SLIST_FOREACH(kn, list, kn_link) {
1254 if (kn->kn_kq == kq &&
1255 kn->kn_filter == kev->filter &&
1256 kn->kn_id == kev->ident &&
1257 kn->kn_uniqifier == uniqifier)
1258 {
1259 if (knote_acquire(kn) == 0)
1260 goto again;
1261 break;
1262 }
1263 }
1264 lwkt_relpooltoken(list);
1265 }
1266
1267 /*
1268 * NOTE: At this point if kn is non-NULL we will have acquired
1269 * it and set KN_PROCESSING.
1270 */
1271 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) {
1272 error = ENOENT;
1273 ++count;
1274 goto done;
1275 }
1276
1277 /*
1278 * kn now contains the matching knote, or NULL if no match
1279 */
1280 if (kev->flags & EV_ADD) {
1281 if (kn == NULL) {
1282 crit_enter();
1283 kn = SLIST_FIRST(&cache_list->knote_cache);
1284 if (kn == NULL) {
1285 crit_exit();
1286 kn = knote_alloc();
1287 } else {
1288 SLIST_REMOVE_HEAD(&cache_list->knote_cache,
1289 kn_link);
1290 cache_list->knote_cache_cnt--;
1291 crit_exit();
1292 }
1293 kn->kn_fp = fp[count];
1294 kn->kn_kq = kq;
1295 kn->kn_fop = fops;
1296 kn->kn_uniqifier = uniqifier;
1297
1298 /*
1299 * apply reference count to knote structure, and
1300 * do not release it at the end of this routine.
1301 */
1302 fp[count] = NULL; /* safety */
1303
1304 kn->kn_sfflags = kev->fflags;
1305 kn->kn_sdata = kev->data;
1306 kev->fflags = 0;
1307 kev->data = 0;
1308 kn->kn_kevent = *kev;
1309
1310 /*
1311 * KN_PROCESSING prevents the knote from getting
1312 * ripped out from under us while we are trying
1313 * to attach it, in case the attach blocks.
1314 */
1315 kn->kn_status = KN_PROCESSING;
1316 knote_attach(kn);
1317 if ((error = filter_attach(kn)) != 0) {
1318 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1319 knote_drop(kn);
1320 ++count;
1321 goto done;
1322 }
1323
1324 /*
1325 * Interlock against close races which either tried
1326 * to remove our knote while we were blocked or missed
1327 * it entirely prior to our attachment. We do not
1328 * want to end up with a knote on a closed descriptor.
1329 */
1330 if ((fops->f_flags & FILTEROP_ISFD) &&
1331 checkfdclosed(curthread, fdp, kev->ident, kn->kn_fp,
1332 closedcounter)) {
1333 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1334 }
1335 } else {
1336 /*
1337 * The user may change some filter values after the
1338 * initial EV_ADD, but doing so will not reset any
1339 * filter which have already been triggered.
1340 */
1341 KKASSERT(kn->kn_status & KN_PROCESSING);
1342 if (fops == &user_filtops) {
1343 filt_usertouch(kn, kev, EVENT_REGISTER);
1344 } else {
1345 kn->kn_sfflags = kev->fflags;
1346 kn->kn_sdata = kev->data;
1347 kn->kn_kevent.udata = kev->udata;
1348 }
1349 }
1350
1351 /*
1352 * Execute the filter event to immediately activate the
1353 * knote if necessary. If reprocessing events are pending
1354 * due to blocking above we do not run the filter here
1355 * but instead let knote_release() do it. Otherwise we
1356 * might run the filter on a deleted event.
1357 */
1358 if ((kn->kn_status & KN_REPROCESS) == 0) {
1359 if (filter_event(kn, 0))
1360 KNOTE_ACTIVATE(kn);
1361 }
1362 } else if (kev->flags & EV_DELETE) {
1363 /*
1364 * Delete the existing knote
1365 */
1366 knote_detach_and_drop(kn);
1367 error = 0;
1368 ++count;
1369 goto done;
1370 } else {
1371 /*
1372 * Modify an existing event.
1373 *
1374 * The user may change some filter values after the
1375 * initial EV_ADD, but doing so will not reset any
1376 * filter which have already been triggered.
1377 */
1378 KKASSERT(kn->kn_status & KN_PROCESSING);
1379 if (fops == &user_filtops) {
1380 filt_usertouch(kn, kev, EVENT_REGISTER);
1381 } else {
1382 kn->kn_sfflags = kev->fflags;
1383 kn->kn_sdata = kev->data;
1384 kn->kn_kevent.udata = kev->udata;
1385 }
1386
1387 /*
1388 * Execute the filter event to immediately activate the
1389 * knote if necessary. If reprocessing events are pending
1390 * due to blocking above we do not run the filter here
1391 * but instead let knote_release() do it. Otherwise we
1392 * might run the filter on a deleted event.
1393 */
1394 if ((kn->kn_status & KN_REPROCESS) == 0) {
1395 if (filter_event(kn, 0))
1396 KNOTE_ACTIVATE(kn);
1397 }
1398 }
1399
1400 /*
1401 * Disablement does not deactivate a knote here.
1402 */
1403 if ((kev->flags & EV_DISABLE) &&
1404 ((kn->kn_status & KN_DISABLED) == 0))
1405 {
1406 kn->kn_status |= KN_DISABLED;
1407 }
1408
1409 /*
1410 * Re-enablement may have to immediately enqueue an active knote.
1411 */
1412 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
1413 kn->kn_status &= ~KN_DISABLED;
1414 if ((kn->kn_status & KN_ACTIVE) &&
1415 ((kn->kn_status & KN_QUEUED) == 0))
1416 {
1417 knote_enqueue(kn);
1418 }
1419 }
1420
1421 /*
1422 * Handle any required reprocessing
1423 */
1424 knote_release(kn);
1425 /* kn may be invalid now */
1426
1427 /*
1428 * Loop control. We stop on errors (above), and also stop after
1429 * processing EV_RECEIPT, so the caller can process it.
1430 */
1431 ++count;
1432 if (kev->flags & EV_RECEIPT) {
1433 error = 0;
1434 goto done;
1435 }
1436 ++kev;
1437 if (count < climit) {
1438 if (fp[count-1]) /* drop unprocessed fp */
1439 fdrop(fp[count-1]);
1440 goto loop;
1441 }
1442
1443 /*
1444 * Cleanup
1445 */
1446 done:
1447 if (td != NULL) { /* Owner of the kq_regtd */
1448 kq->kq_regtd = NULL;
1449 if (__predict_false(kq->kq_state & KQ_REGWAIT)) {
1450 kq->kq_state &= ~KQ_REGWAIT;
1451 wakeup(&kq->kq_regtd);
1452 }
1453 }
1454 lwkt_relpooltoken(kq);
1455
1456 /*
1457 * Drop unprocessed file pointers
1458 */
1459 *countp = count;
1460 if (count && fp[count-1])
1461 fdrop(fp[count-1]);
1462 while (count < climit) {
1463 if (fp[count])
1464 fdrop(fp[count]);
1465 ++count;
1466 }
1467 return (error);
1468 }
1469
1470 /*
1471 * Scan the kqueue, return the number of active events placed in kevp up
1472 * to count.
1473 *
1474 * Continuous mode events may get recycled, do not continue scanning past
1475 * marker unless no events have been collected.
1476 */
1477 static int
1478 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
1479 struct knote *marker, int closedcounter, int flags)
1480 {
1481 struct knote *kn, local_marker;
1482 thread_t td = curthread;
1483 int total;
1484
1485 total = 0;
1486 local_marker.kn_filter = EVFILT_MARKER;
1487 local_marker.kn_status = KN_PROCESSING;
1488
1489 lwkt_getpooltoken(kq);
1490
1491 /*
1492 * Adjust marker, insert initial marker, or leave the marker alone.
1493 *
1494 * Also setup our local_marker.
1495 */
1496 switch(flags & KEVENT_SCAN_MASK) {
1497 case KEVENT_SCAN_RELOAD_MARKER:
1498 TAILQ_REMOVE(&kq->kq_knpend, marker, kn_tqe);
1499 /* fall through */
1500 case KEVENT_SCAN_INSERT_MARKER:
1501 TAILQ_INSERT_TAIL(&kq->kq_knpend, marker, kn_tqe);
1502 break;
1503 }
1504 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe);
1505
1506 /*
1507 * Collect events.
1508 */
1509 while (count) {
1510 kn = TAILQ_NEXT(&local_marker, kn_tqe);
1511 if (kn->kn_filter == EVFILT_MARKER) {
1512 /* Marker reached, we are done */
1513 if (kn == marker)
1514 break;
1515
1516 /* Move local marker past some other threads marker */
1517 kn = TAILQ_NEXT(kn, kn_tqe);
1518 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1519 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe);
1520 continue;
1521 }
1522
1523 /*
1524 * We can't skip a knote undergoing processing, otherwise
1525 * we risk not returning it when the user process expects
1526 * it should be returned. Sleep and retry.
1527 */
1528 if (knote_acquire(kn) == 0)
1529 continue;
1530
1531 /*
1532 * Remove the event for processing.
1533 *
1534 * WARNING! We must leave KN_QUEUED set to prevent the
1535 * event from being KNOTE_ACTIVATE()d while
1536 * the queue state is in limbo, in case we
1537 * block.
1538 */
1539 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
1540 kq->kq_count--;
1541
1542 /*
1543 * Kernel select() and poll() functions cache previous
1544 * operations on the assumption that future operations
1545 * will use similr descriptor sets. This removes any
1546 * stale entries in a way that does not require a descriptor
1547 * lookup and is thus not affected by close() races.
1548 *
1549 * Do not report to *_copyout()
1550 */
1551 if (flags & KEVENT_AUTO_STALE) {
1552 if ((uint64_t)kn->kn_kevent.udata <
1553 curthread->td_lwp->lwp_kqueue_serial)
1554 {
1555 kn->kn_status |= KN_DELETING | KN_REPROCESS |
1556 KN_DISABLED;
1557 }
1558 }
1559
1560 /*
1561 * If a descriptor is close()d out from under a poll/select,
1562 * we want to report the event but delete the note because
1563 * the note can wind up being 'stuck' on kq_knpend.
1564 */
1565 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) &&
1566 checkfdclosed(td, kq->kq_fdp, kn->kn_kevent.ident,
1567 kn->kn_fp, closedcounter))
1568 {
1569 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1570 }
1571
1572 if (kn->kn_status & KN_DISABLED) {
1573 /*
1574 * If disabled we ensure the event is not queued
1575 * but leave its active bit set. On re-enablement
1576 * the event may be immediately triggered.
1577 */
1578 kn->kn_status &= ~KN_QUEUED;
1579 } else if ((kn->kn_flags & EV_ONESHOT) == 0 &&
1580 (kn->kn_status & KN_DELETING) == 0 &&
1581 filter_event(kn, 0) == 0) {
1582 /*
1583 * If not running in one-shot mode and the event
1584 * is no longer present we ensure it is removed
1585 * from the queue and ignore it.
1586 */
1587 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
1588 } else {
1589 /*
1590 * Post the event
1591 */
1592 if (kn->kn_fop == &user_filtops)
1593 filt_usertouch(kn, kevp, EVENT_PROCESS);
1594 else
1595 *kevp = kn->kn_kevent;
1596 ++kevp;
1597 ++total;
1598 --count;
1599
1600 if (kn->kn_flags & EV_ONESHOT) {
1601 kn->kn_status &= ~KN_QUEUED;
1602 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1603 } else {
1604 if (kn->kn_flags & (EV_CLEAR | EV_DISPATCH)) {
1605 if (kn->kn_flags & EV_CLEAR) {
1606 kn->kn_data = 0;
1607 kn->kn_fflags = 0;
1608 }
1609 if (kn->kn_flags & EV_DISPATCH) {
1610 kn->kn_status |= KN_DISABLED;
1611 }
1612 kn->kn_status &= ~(KN_QUEUED |
1613 KN_ACTIVE);
1614 } else {
1615 TAILQ_INSERT_TAIL(&kq->kq_knpend,
1616 kn,
1617 kn_tqe);
1618 kq->kq_count++;
1619 }
1620 }
1621 }
1622
1623 /*
1624 * Handle any post-processing states
1625 */
1626 knote_release(kn);
1627 }
1628 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1629
1630 lwkt_relpooltoken(kq);
1631 return (total);
1632 }
1633
1634 /*
1635 * XXX
1636 * This could be expanded to call kqueue_scan, if desired.
1637 *
1638 * MPSAFE
1639 */
1640 static int
1641 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1642 {
1643 return (ENXIO);
1644 }
1645
1646 /*
1647 * MPSAFE
1648 */
1649 static int
1650 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1651 {
1652 return (ENXIO);
1653 }
1654
1655 /*
1656 * MPALMOSTSAFE
1657 */
1658 static int
1659 kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
1660 struct ucred *cred, struct sysmsg *msg)
1661 {
1662 struct kqueue *kq;
1663 int error;
1664
1665 kq = (struct kqueue *)fp->f_data;
1666 lwkt_getpooltoken(kq);
1667 switch(com) {
1668 case FIOASYNC:
1669 if (*(int *)data)
1670 kq->kq_state |= KQ_ASYNC;
1671 else
1672 kq->kq_state &= ~KQ_ASYNC;
1673 error = 0;
1674 break;
1675 case FIOSETOWN:
1676 error = fsetown(*(int *)data, &kq->kq_sigio);
1677 break;
1678 default:
1679 error = ENOTTY;
1680 break;
1681 }
1682 lwkt_relpooltoken(kq);
1683 return (error);
1684 }
1685
1686 /*
1687 * MPSAFE
1688 */
1689 static int
1690 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred)
1691 {
1692 struct kqueue *kq = (struct kqueue *)fp->f_data;
1693
1694 bzero((void *)st, sizeof(*st));
1695 st->st_size = kq->kq_count;
1696 st->st_blksize = sizeof(struct kevent);
1697 st->st_mode = S_IFIFO;
1698 return (0);
1699 }
1700
1701 /*
1702 * MPSAFE
1703 */
1704 static int
1705 kqueue_close(struct file *fp)
1706 {
1707 struct kqueue *kq = (struct kqueue *)fp->f_data;
1708
1709 kqueue_terminate(kq);
1710
1711 fp->f_data = NULL;
1712 funsetown(&kq->kq_sigio);
1713
1714 kfree(kq, M_KQUEUE);
1715 return (0);
1716 }
1717
1718 static void
1719 kqueue_wakeup(struct kqueue *kq)
1720 {
1721 if (kq->kq_sleep_cnt) {
1722 u_int sleep_cnt = kq->kq_sleep_cnt;
1723
1724 kq->kq_sleep_cnt = 0;
1725 if (sleep_cnt == 1)
1726 wakeup_one(kq);
1727 else
1728 wakeup(kq);
1729 }
1730 KNOTE(&kq->kq_kqinfo.ki_note, 0);
1731 }
1732
1733 /*
1734 * Calls filterops f_attach function, acquiring mplock if filter is not
1735 * marked as FILTEROP_MPSAFE.
1736 *
1737 * Caller must be holding the related kq token
1738 */
1739 static int
1740 filter_attach(struct knote *kn)
1741 {
1742 int ret;
1743
1744 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1745 ret = kn->kn_fop->f_attach(kn);
1746 } else {
1747 get_mplock();
1748 ret = kn->kn_fop->f_attach(kn);
1749 rel_mplock();
1750 }
1751 return (ret);
1752 }
1753
1754 /*
1755 * Detach the knote and drop it, destroying the knote.
1756 *
1757 * Calls filterops f_detach function, acquiring mplock if filter is not
1758 * marked as FILTEROP_MPSAFE.
1759 *
1760 * Caller must be holding the related kq token
1761 */
1762 static void
1763 knote_detach_and_drop(struct knote *kn)
1764 {
1765 kn->kn_status |= KN_DELETING | KN_REPROCESS;
1766 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1767 kn->kn_fop->f_detach(kn);
1768 } else {
1769 get_mplock();
1770 kn->kn_fop->f_detach(kn);
1771 rel_mplock();
1772 }
1773 knote_drop(kn);
1774 }
1775
1776 /*
1777 * Calls filterops f_event function, acquiring mplock if filter is not
1778 * marked as FILTEROP_MPSAFE.
1779 *
1780 * If the knote is in the middle of being created or deleted we cannot
1781 * safely call the filter op.
1782 *
1783 * Caller must be holding the related kq token
1784 */
1785 static int
1786 filter_event(struct knote *kn, long hint)
1787 {
1788 int ret;
1789
1790 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1791 ret = kn->kn_fop->f_event(kn, hint);
1792 } else {
1793 get_mplock();
1794 ret = kn->kn_fop->f_event(kn, hint);
1795 rel_mplock();
1796 }
1797 return (ret);
1798 }
1799
1800 /*
1801 * Walk down a list of knotes, activating them if their event has triggered.
1802 *
1803 * If we encounter any knotes which are undergoing processing we just mark
1804 * them for reprocessing and do not try to [re]activate the knote. However,
1805 * if a hint is being passed we have to wait and that makes things a bit
1806 * sticky.
1807 */
1808 void
1809 knote(struct klist *list, long hint)
1810 {
1811 struct kqueue *kq;
1812 struct knote *kn;
1813 struct knote *kntmp;
1814
1815 lwkt_getpooltoken(list);
1816 restart:
1817 SLIST_FOREACH(kn, list, kn_next) {
1818 kq = kn->kn_kq;
1819 lwkt_getpooltoken(kq);
1820
1821 /* temporary verification hack */
1822 SLIST_FOREACH(kntmp, list, kn_next) {
1823 if (kn == kntmp)
1824 break;
1825 }
1826 if (kn != kntmp || kn->kn_kq != kq) {
1827 lwkt_relpooltoken(kq);
1828 goto restart;
1829 }
1830
1831 if (kn->kn_status & KN_PROCESSING) {
1832 /*
1833 * Someone else is processing the knote, ask the
1834 * other thread to reprocess it and don't mess
1835 * with it otherwise.
1836 */
1837 if (hint == 0) {
1838 kn->kn_status |= KN_REPROCESS;
1839 lwkt_relpooltoken(kq);
1840 continue;
1841 }
1842
1843 /*
1844 * If the hint is non-zero we have to wait or risk
1845 * losing the state the caller is trying to update.
1846 *
1847 * XXX This is a real problem, certain process
1848 * and signal filters will bump kn_data for
1849 * already-processed notes more than once if
1850 * we restart the list scan. FIXME.
1851 */
1852 kn->kn_status |= KN_WAITING | KN_REPROCESS;
1853 tsleep(kn, 0, "knotec", hz);
1854 lwkt_relpooltoken(kq);
1855 goto restart;
1856 }
1857
1858 /*
1859 * Become the reprocessing master ourselves.
1860 *
1861 * If hint is non-zero running the event is mandatory
1862 * when not deleting so do it whether reprocessing is
1863 * set or not.
1864 */
1865 kn->kn_status |= KN_PROCESSING;
1866 if ((kn->kn_status & KN_DELETING) == 0) {
1867 if (filter_event(kn, hint))
1868 KNOTE_ACTIVATE(kn);
1869 }
1870 if (knote_release(kn)) {
1871 lwkt_relpooltoken(kq);
1872 goto restart;
1873 }
1874 lwkt_relpooltoken(kq);
1875 }
1876 lwkt_relpooltoken(list);
1877 }
1878
1879 /*
1880 * Insert knote at head of klist.
1881 *
1882 * This function may only be called via a filter function and thus
1883 * kq_token should already be held and marked for processing.
1884 */
1885 void
1886 knote_insert(struct klist *klist, struct knote *kn)
1887 {
1888 lwkt_getpooltoken(klist);
1889 KKASSERT(kn->kn_status & KN_PROCESSING);
1890 SLIST_INSERT_HEAD(klist, kn, kn_next);
1891 lwkt_relpooltoken(klist);
1892 }
1893
1894 /*
1895 * Remove knote from a klist
1896 *
1897 * This function may only be called via a filter function and thus
1898 * kq_token should already be held and marked for processing.
1899 */
1900 void
1901 knote_remove(struct klist *klist, struct knote *kn)
1902 {
1903 lwkt_getpooltoken(klist);
1904 KKASSERT(kn->kn_status & KN_PROCESSING);
1905 SLIST_REMOVE(klist, kn, knote, kn_next);
1906 lwkt_relpooltoken(klist);
1907 }
1908
1909 void
1910 knote_assume_knotes(struct kqinfo *src, struct kqinfo *dst,
1911 struct filterops *ops, void *hook)
1912 {
1913 struct kqueue *kq;
1914 struct knote *kn;
1915
1916 lwkt_getpooltoken(&src->ki_note);
1917 lwkt_getpooltoken(&dst->ki_note);
1918 while ((kn = SLIST_FIRST(&src->ki_note)) != NULL) {
1919 kq = kn->kn_kq;
1920 lwkt_getpooltoken(kq);
1921 if (SLIST_FIRST(&src->ki_note) != kn || kn->kn_kq != kq) {
1922 lwkt_relpooltoken(kq);
1923 continue;
1924 }
1925 if (knote_acquire(kn)) {
1926 knote_remove(&src->ki_note, kn);
1927 kn->kn_fop = ops;
1928 kn->kn_hook = hook;
1929 knote_insert(&dst->ki_note, kn);
1930 knote_release(kn);
1931 /* kn may be invalid now */
1932 }
1933 lwkt_relpooltoken(kq);
1934 }
1935 lwkt_relpooltoken(&dst->ki_note);
1936 lwkt_relpooltoken(&src->ki_note);
1937 }
1938
1939 /*
1940 * Remove all knotes referencing a specified fd
1941 */
1942 void
1943 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd)
1944 {
1945 struct kqueue *kq;
1946 struct knote *kn;
1947 struct knote *kntmp;
1948
1949 lwkt_getpooltoken(&fp->f_klist);
1950 restart:
1951 SLIST_FOREACH(kn, &fp->f_klist, kn_link) {
1952 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) {
1953 kq = kn->kn_kq;
1954 lwkt_getpooltoken(kq);
1955
1956 /* temporary verification hack */
1957 SLIST_FOREACH(kntmp, &fp->f_klist, kn_link) {
1958 if (kn == kntmp)
1959 break;
1960 }
1961 if (kn != kntmp || kn->kn_kq->kq_fdp != fdp ||
1962 kn->kn_id != fd || kn->kn_kq != kq) {
1963 lwkt_relpooltoken(kq);
1964 goto restart;
1965 }
1966 if (knote_acquire(kn))
1967 knote_detach_and_drop(kn);
1968 lwkt_relpooltoken(kq);
1969 goto restart;
1970 }
1971 }
1972 lwkt_relpooltoken(&fp->f_klist);
1973 }
1974
1975 /*
1976 * Low level attach function.
1977 *
1978 * The knote should already be marked for processing.
1979 * Caller must hold the related kq token.
1980 */
1981 static void
1982 knote_attach(struct knote *kn)
1983 {
1984 struct klist *list;
1985 struct kqueue *kq = kn->kn_kq;
1986
1987 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1988 KKASSERT(kn->kn_fp);
1989 list = &kn->kn_fp->f_klist;
1990 } else {
1991 if (kq->kq_knhashmask == 0)
1992 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
1993 &kq->kq_knhashmask);
1994 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1995 }
1996 lwkt_getpooltoken(list);
1997 SLIST_INSERT_HEAD(list, kn, kn_link);
1998 lwkt_relpooltoken(list);
1999 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink);
2000 }
2001
2002 /*
2003 * Low level drop function.
2004 *
2005 * The knote should already be marked for processing.
2006 * Caller must hold the related kq token.
2007 */
2008 static void
2009 knote_drop(struct knote *kn)
2010 {
2011 struct kqueue *kq;
2012 struct klist *list;
2013
2014 kq = kn->kn_kq;
2015
2016 if (kn->kn_fop->f_flags & FILTEROP_ISFD)
2017 list = &kn->kn_fp->f_klist;
2018 else
2019 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
2020
2021 lwkt_getpooltoken(list);
2022 SLIST_REMOVE(list, kn, knote, kn_link);
2023 lwkt_relpooltoken(list);
2024 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink);
2025 if (kn->kn_status & KN_QUEUED)
2026 knote_dequeue(kn);
2027 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
2028 fdrop(kn->kn_fp);
2029 kn->kn_fp = NULL;
2030 }
2031 knote_free(kn);
2032 }
2033
2034 /*
2035 * Low level enqueue function.
2036 *
2037 * The knote should already be marked for processing.
2038 * Caller must be holding the kq token
2039 */
2040 static void
2041 knote_enqueue(struct knote *kn)
2042 {
2043 struct kqueue *kq = kn->kn_kq;
2044
2045 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
2046 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
2047 kn->kn_status |= KN_QUEUED;
2048 ++kq->kq_count;
2049
2050 /*
2051 * Send SIGIO on request (typically set up as a mailbox signal)
2052 */
2053 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1)
2054 pgsigio(kq->kq_sigio, SIGIO, 0);
2055
2056 kqueue_wakeup(kq);
2057 }
2058
2059 /*
2060 * Low level dequeue function.
2061 *
2062 * The knote should already be marked for processing.
2063 * Caller must be holding the kq token
2064 */
2065 static void
2066 knote_dequeue(struct knote *kn)
2067 {
2068 struct kqueue *kq = kn->kn_kq;
2069
2070 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
2071 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
2072 kn->kn_status &= ~KN_QUEUED;
2073 kq->kq_count--;
2074 }
2075
2076 static struct knote *
2077 knote_alloc(void)
2078 {
2079 return kmalloc(sizeof(struct knote), M_KQUEUE, M_WAITOK);
2080 }
2081
2082 static void
2083 knote_free(struct knote *kn)
2084 {
2085 struct knote_cache_list *cache_list;
2086
2087 cache_list = &knote_cache_lists[mycpuid];
2088 if (cache_list->knote_cache_cnt < KNOTE_CACHE_MAX) {
2089 crit_enter();
2090 SLIST_INSERT_HEAD(&cache_list->knote_cache, kn, kn_link);
2091 cache_list->knote_cache_cnt++;
2092 crit_exit();
2093 return;
2094 }
2095 kfree(kn, M_KQUEUE);
2096 }
2097
2098 struct sleepinfo {
2099 void *ident;
2100 int timedout;
2101 };
2102
2103 static void
2104 precise_sleep_intr(systimer_t info, int in_ipi, struct intrframe *frame)
2105 {
2106 struct sleepinfo *si;
2107
2108 si = info->data;
2109 si->timedout = 1;
2110 wakeup(si->ident);
2111 }
2112
2113 static int
2114 precise_sleep(void *ident, int flags, const char *wmesg, int us)
2115 {
2116 struct systimer info;
2117 struct sleepinfo si = {
2118 .ident = ident,
2119 .timedout = 0,
2120 };
2121 int r;
2122
2123 tsleep_interlock(ident, flags);
2124 systimer_init_oneshot(&info, precise_sleep_intr, &si, us);
2125 r = tsleep(ident, flags | PINTERLOCKED, wmesg, 0);
2126 systimer_del(&info);
2127 if (si.timedout)
2128 r = EWOULDBLOCK;
2129
2130 return r;
2131 }
DragonFly BSD