2 * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
26 * $FreeBSD: src/sys/kern/kern_event.c,v 1.2.2.10 2004/04/04 07:03:14 cperciva Exp $
27 * $DragonFly: src/sys/kern/kern_event.c,v 1.33 2007/02/03 17:05:57 corecode Exp $
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/kernel.h>
34 #include <sys/malloc.h>
35 #include <sys/unistd.h>
38 #include <sys/fcntl.h>
39 #include <sys/queue.h>
40 #include <sys/event.h>
41 #include <sys/eventvar.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
44 #include <sys/socketvar.h>
46 #include <sys/sysctl.h>
47 #include <sys/sysproto.h>
48 #include <sys/thread.h>
50 #include <sys/signalvar.h>
51 #include <sys/filio.h>
54 #include <sys/thread2.h>
55 #include <sys/file2.h>
56 #include <sys/mplock2.h>
58 #include <vm/vm_zone.h>
61 * Global token for kqueue subsystem
63 struct lwkt_token kq_token = LWKT_TOKEN_UP_INITIALIZER(kq_token);
65 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
67 struct kevent_copyin_args {
68 struct kevent_args *ka;
72 static int kqueue_sleep(struct kqueue *kq, struct timespec *tsp);
73 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
74 struct knote *marker);
75 static int kqueue_read(struct file *fp, struct uio *uio,
76 struct ucred *cred, int flags);
77 static int kqueue_write(struct file *fp, struct uio *uio,
78 struct ucred *cred, int flags);
79 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
80 struct ucred *cred, struct sysmsg *msg);
81 static int kqueue_kqfilter(struct file *fp, struct knote *kn);
82 static int kqueue_stat(struct file *fp, struct stat *st,
84 static int kqueue_close(struct file *fp);
85 static void kqueue_wakeup(struct kqueue *kq);
86 static int filter_attach(struct knote *kn);
87 static int filter_event(struct knote *kn, long hint);
92 static struct fileops kqueueops = {
93 .fo_read = kqueue_read,
94 .fo_write = kqueue_write,
95 .fo_ioctl = kqueue_ioctl,
96 .fo_kqfilter = kqueue_kqfilter,
97 .fo_stat = kqueue_stat,
98 .fo_close = kqueue_close,
99 .fo_shutdown = nofo_shutdown
102 static void knote_attach(struct knote *kn);
103 static void knote_drop(struct knote *kn);
104 static void knote_detach_and_drop(struct knote *kn);
105 static void knote_enqueue(struct knote *kn);
106 static void knote_dequeue(struct knote *kn);
107 static void knote_init(void);
108 static struct knote *knote_alloc(void);
109 static void knote_free(struct knote *kn);
111 static void filt_kqdetach(struct knote *kn);
112 static int filt_kqueue(struct knote *kn, long hint);
113 static int filt_procattach(struct knote *kn);
114 static void filt_procdetach(struct knote *kn);
115 static int filt_proc(struct knote *kn, long hint);
116 static int filt_fileattach(struct knote *kn);
117 static void filt_timerexpire(void *knx);
118 static int filt_timerattach(struct knote *kn);
119 static void filt_timerdetach(struct knote *kn);
120 static int filt_timer(struct knote *kn, long hint);
122 static struct filterops file_filtops =
123 { FILTEROP_ISFD, filt_fileattach, NULL, NULL };
124 static struct filterops kqread_filtops =
125 { FILTEROP_ISFD, NULL, filt_kqdetach, filt_kqueue };
126 static struct filterops proc_filtops =
127 { 0, filt_procattach, filt_procdetach, filt_proc };
128 static struct filterops timer_filtops =
129 { 0, filt_timerattach, filt_timerdetach, filt_timer };
131 static vm_zone_t knote_zone;
132 static int kq_ncallouts = 0;
133 static int kq_calloutmax = (4 * 1024);
134 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
135 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
136 static int kq_checkloop = 1000000;
137 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW,
138 &kq_checkloop, 0, "Maximum number of callouts allocated for kqueue");
140 #define KNOTE_ACTIVATE(kn) do { \
141 kn->kn_status |= KN_ACTIVE; \
142 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \
146 #define KN_HASHSIZE 64 /* XXX should be tunable */
147 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask))
149 extern struct filterops aio_filtops;
150 extern struct filterops sig_filtops;
153 * Table for for all system-defined filters.
155 static struct filterops *sysfilt_ops[] = {
156 &file_filtops, /* EVFILT_READ */
157 &file_filtops, /* EVFILT_WRITE */
158 &aio_filtops, /* EVFILT_AIO */
159 &file_filtops, /* EVFILT_VNODE */
160 &proc_filtops, /* EVFILT_PROC */
161 &sig_filtops, /* EVFILT_SIGNAL */
162 &timer_filtops, /* EVFILT_TIMER */
163 &file_filtops, /* EVFILT_EXCEPT */
167 filt_fileattach(struct knote *kn)
169 return (fo_kqfilter(kn->kn_fp, kn));
176 kqueue_kqfilter(struct file *fp, struct knote *kn)
178 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
180 if (kn->kn_filter != EVFILT_READ)
183 kn->kn_fop = &kqread_filtops;
184 knote_insert(&kq->kq_kqinfo.ki_note, kn);
189 filt_kqdetach(struct knote *kn)
191 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
193 knote_remove(&kq->kq_kqinfo.ki_note, kn);
198 filt_kqueue(struct knote *kn, long hint)
200 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
202 kn->kn_data = kq->kq_count;
203 return (kn->kn_data > 0);
207 filt_procattach(struct knote *kn)
213 lwkt_gettoken(&proc_token);
214 p = pfind(kn->kn_id);
215 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
216 p = zpfind(kn->kn_id);
220 lwkt_reltoken(&proc_token);
223 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) {
224 lwkt_reltoken(&proc_token);
228 kn->kn_ptr.p_proc = p;
229 kn->kn_flags |= EV_CLEAR; /* automatically set */
232 * internal flag indicating registration done by kernel
234 if (kn->kn_flags & EV_FLAG1) {
235 kn->kn_data = kn->kn_sdata; /* ppid */
236 kn->kn_fflags = NOTE_CHILD;
237 kn->kn_flags &= ~EV_FLAG1;
240 knote_insert(&p->p_klist, kn);
243 * Immediately activate any exit notes if the target process is a
244 * zombie. This is necessary to handle the case where the target
245 * process, e.g. a child, dies before the kevent is negistered.
247 if (immediate && filt_proc(kn, NOTE_EXIT))
249 lwkt_reltoken(&proc_token);
255 * The knote may be attached to a different process, which may exit,
256 * leaving nothing for the knote to be attached to. So when the process
257 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
258 * it will be deleted when read out. However, as part of the knote deletion,
259 * this routine is called, so a check is needed to avoid actually performing
260 * a detach, because the original process does not exist any more.
263 filt_procdetach(struct knote *kn)
267 if (kn->kn_status & KN_DETACHED)
269 /* XXX locking? take proc_token here? */
270 p = kn->kn_ptr.p_proc;
271 knote_remove(&p->p_klist, kn);
275 filt_proc(struct knote *kn, long hint)
280 * mask off extra data
282 event = (u_int)hint & NOTE_PCTRLMASK;
285 * if the user is interested in this event, record it.
287 if (kn->kn_sfflags & event)
288 kn->kn_fflags |= event;
291 * Process is gone, so flag the event as finished. Detach the
292 * knote from the process now because the process will be poof,
295 if (event == NOTE_EXIT) {
296 struct proc *p = kn->kn_ptr.p_proc;
297 if ((kn->kn_status & KN_DETACHED) == 0) {
298 knote_remove(&p->p_klist, kn);
299 kn->kn_status |= KN_DETACHED;
300 kn->kn_data = p->p_xstat;
301 kn->kn_ptr.p_proc = NULL;
303 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
308 * process forked, and user wants to track the new process,
309 * so attach a new knote to it, and immediately report an
310 * event with the parent's pid.
312 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) {
317 * register knote with new process.
319 kev.ident = hint & NOTE_PDATAMASK; /* pid */
320 kev.filter = kn->kn_filter;
321 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
322 kev.fflags = kn->kn_sfflags;
323 kev.data = kn->kn_id; /* parent */
324 kev.udata = kn->kn_kevent.udata; /* preserve udata */
325 error = kqueue_register(kn->kn_kq, &kev);
327 kn->kn_fflags |= NOTE_TRACKERR;
330 return (kn->kn_fflags != 0);
334 filt_timerexpire(void *knx)
336 struct knote *kn = knx;
337 struct callout *calloutp;
344 if ((kn->kn_flags & EV_ONESHOT) == 0) {
345 tv.tv_sec = kn->kn_sdata / 1000;
346 tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
347 tticks = tvtohz_high(&tv);
348 calloutp = (struct callout *)kn->kn_hook;
349 callout_reset(calloutp, tticks, filt_timerexpire, kn);
354 * data contains amount of time to sleep, in milliseconds
357 filt_timerattach(struct knote *kn)
359 struct callout *calloutp;
363 if (kq_ncallouts >= kq_calloutmax)
367 tv.tv_sec = kn->kn_sdata / 1000;
368 tv.tv_usec = (kn->kn_sdata % 1000) * 1000;
369 tticks = tvtohz_high(&tv);
371 kn->kn_flags |= EV_CLEAR; /* automatically set */
372 MALLOC(calloutp, struct callout *, sizeof(*calloutp),
374 callout_init(calloutp);
375 kn->kn_hook = (caddr_t)calloutp;
376 callout_reset(calloutp, tticks, filt_timerexpire, kn);
382 filt_timerdetach(struct knote *kn)
384 struct callout *calloutp;
386 calloutp = (struct callout *)kn->kn_hook;
387 callout_stop(calloutp);
388 FREE(calloutp, M_KQUEUE);
393 filt_timer(struct knote *kn, long hint)
396 return (kn->kn_data != 0);
400 * Initialize a kqueue.
402 * NOTE: The lwp/proc code initializes a kqueue for select/poll ops.
407 kqueue_init(struct kqueue *kq, struct filedesc *fdp)
409 TAILQ_INIT(&kq->kq_knpend);
410 TAILQ_INIT(&kq->kq_knlist);
413 SLIST_INIT(&kq->kq_kqinfo.ki_note);
417 * Terminate a kqueue. Freeing the actual kq itself is left up to the
418 * caller (it might be embedded in a lwp so we don't do it here).
421 kqueue_terminate(struct kqueue *kq)
425 lwkt_gettoken(&kq_token);
426 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL)
427 knote_detach_and_drop(kn);
430 kfree(kq->kq_knhash, M_KQUEUE);
431 kq->kq_knhash = NULL;
432 kq->kq_knhashmask = 0;
434 lwkt_reltoken(&kq_token);
441 sys_kqueue(struct kqueue_args *uap)
443 struct thread *td = curthread;
448 error = falloc(td->td_lwp, &fp, &fd);
451 fp->f_flag = FREAD | FWRITE;
452 fp->f_type = DTYPE_KQUEUE;
453 fp->f_ops = &kqueueops;
455 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO);
456 kqueue_init(kq, td->td_proc->p_fd);
459 fsetfd(kq->kq_fdp, fp, fd);
460 uap->sysmsg_result = fd;
466 * Copy 'count' items into the destination list pointed to by uap->eventlist.
469 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res)
471 struct kevent_copyin_args *kap;
474 kap = (struct kevent_copyin_args *)arg;
476 error = copyout(kevp, kap->ka->eventlist, count * sizeof(*kevp));
478 kap->ka->eventlist += count;
488 * Copy at most 'max' items from the list pointed to by kap->changelist,
489 * return number of items in 'events'.
492 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events)
494 struct kevent_copyin_args *kap;
497 kap = (struct kevent_copyin_args *)arg;
499 count = min(kap->ka->nchanges - kap->pchanges, max);
500 error = copyin(kap->ka->changelist, kevp, count * sizeof *kevp);
502 kap->ka->changelist += count;
503 kap->pchanges += count;
514 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap,
515 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn,
516 struct timespec *tsp_in)
519 struct timespec *tsp;
520 int i, n, total, error, nerrors = 0;
522 int limit = kq_checkloop;
523 struct kevent kev[KQ_NEVENTS];
529 lwkt_gettoken(&kq_token);
532 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n);
537 for (i = 0; i < n; i++) {
539 kevp->flags &= ~EV_SYSFLAGS;
540 error = kqueue_register(kq, kevp);
543 * If a registration returns an error we
544 * immediately post the error. The kevent()
545 * call itself will fail with the error if
546 * no space is available for posting.
548 * Such errors normally bypass the timeout/blocking
549 * code. However, if the copyoutfn function refuses
550 * to post the error (see sys_poll()), then we
554 kevp->flags = EV_ERROR;
557 kevent_copyoutfn(uap, kevp, 1, res);
571 * Acquire/wait for events - setup timeout
576 if (tsp->tv_sec || tsp->tv_nsec) {
578 timespecadd(tsp, &ats); /* tsp = target time */
585 * Collect as many events as we can. Sleeping on successive
586 * loops is disabled if copyoutfn has incremented (*res).
588 * The loop stops if an error occurs, all events have been
589 * scanned (the marker has been reached), or fewer than the
590 * maximum number of events is found.
592 * The copyoutfn function does not have to increment (*res) in
593 * order for the loop to continue.
595 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents.
599 marker.kn_filter = EVFILT_MARKER;
600 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
601 while ((n = nevents - total) > 0) {
606 * If no events are pending sleep until timeout (if any)
607 * or an event occurs.
609 * After the sleep completes the marker is moved to the
610 * end of the list, making any received events available
613 if (kq->kq_count == 0 && *res == 0) {
614 error = kqueue_sleep(kq, tsp);
618 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
619 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
623 * Process all received events
624 * Account for all non-spurious events in our total
626 i = kqueue_scan(kq, kev, n, &marker);
629 error = kevent_copyoutfn(uap, kev, i, res);
630 total += *res - lres;
634 if (limit && --limit == 0)
635 panic("kqueue: checkloop failed i=%d", i);
638 * Normally when fewer events are returned than requested
639 * we can stop. However, if only spurious events were
640 * collected the copyout will not bump (*res) and we have
647 * Deal with an edge case where spurious events can cause
648 * a loop to occur without moving the marker. This can
649 * prevent kqueue_scan() from picking up new events which
650 * race us. We must be sure to move the marker for this
653 * NOTE: We do not want to move the marker if events
654 * were scanned because normal kqueue operations
655 * may reactivate events. Moving the marker in
656 * that case could result in duplicates for the
660 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
661 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);
664 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe);
666 /* Timeouts do not return EWOULDBLOCK. */
667 if (error == EWOULDBLOCK)
671 lwkt_reltoken(&kq_token);
679 sys_kevent(struct kevent_args *uap)
681 struct thread *td = curthread;
682 struct proc *p = td->td_proc;
683 struct timespec ts, *tsp;
685 struct file *fp = NULL;
686 struct kevent_copyin_args *kap, ka;
690 error = copyin(uap->timeout, &ts, sizeof(ts));
698 fp = holdfp(p->p_fd, uap->fd, -1);
701 if (fp->f_type != DTYPE_KQUEUE) {
706 kq = (struct kqueue *)fp->f_data;
712 error = kern_kevent(kq, uap->nevents, &uap->sysmsg_result, kap,
713 kevent_copyin, kevent_copyout, tsp);
721 kqueue_register(struct kqueue *kq, struct kevent *kev)
723 struct filedesc *fdp = kq->kq_fdp;
724 struct filterops *fops;
725 struct file *fp = NULL;
726 struct knote *kn = NULL;
729 if (kev->filter < 0) {
730 if (kev->filter + EVFILT_SYSCOUNT < 0)
732 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */
736 * filter attach routine is responsible for insuring that
737 * the identifier can be attached to it.
739 kprintf("unknown filter: %d\n", kev->filter);
743 lwkt_gettoken(&kq_token);
744 if (fops->f_flags & FILTEROP_ISFD) {
745 /* validate descriptor */
746 fp = holdfp(fdp, kev->ident, -1);
748 lwkt_reltoken(&kq_token);
752 SLIST_FOREACH(kn, &fp->f_klist, kn_link) {
753 if (kn->kn_kq == kq &&
754 kn->kn_filter == kev->filter &&
755 kn->kn_id == kev->ident) {
760 if (kq->kq_knhashmask) {
763 list = &kq->kq_knhash[
764 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
765 SLIST_FOREACH(kn, list, kn_link) {
766 if (kn->kn_id == kev->ident &&
767 kn->kn_filter == kev->filter)
773 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) {
779 * kn now contains the matching knote, or NULL if no match
781 if (kev->flags & EV_ADD) {
793 * apply reference count to knote structure, and
794 * do not release it at the end of this routine.
798 kn->kn_sfflags = kev->fflags;
799 kn->kn_sdata = kev->data;
802 kn->kn_kevent = *kev;
805 * Interlock against creation/deletion races due
806 * to f_attach() blocking. knote_attach() will set
810 if ((error = filter_attach(kn)) != 0) {
811 kn->kn_status |= KN_DELETING;
815 kn->kn_status &= ~KN_CREATING;
818 * Interlock against close races which remove our
819 * knotes. We do not want to end up with a knote
820 * on a closed descriptor.
822 if ((fops->f_flags & FILTEROP_ISFD) &&
823 (error = checkfdclosed(fdp, kev->ident, kn->kn_fp)) != 0) {
824 knote_detach_and_drop(kn);
829 * The user may change some filter values after the
830 * initial EV_ADD, but doing so will not reset any
831 * filter which have already been triggered.
833 kn->kn_sfflags = kev->fflags;
834 kn->kn_sdata = kev->data;
835 kn->kn_kevent.udata = kev->udata;
838 if (filter_event(kn, 0))
840 } else if (kev->flags & EV_DELETE) {
841 knote_detach_and_drop(kn);
845 if ((kev->flags & EV_DISABLE) &&
846 ((kn->kn_status & KN_DISABLED) == 0)) {
847 kn->kn_status |= KN_DISABLED;
850 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
851 kn->kn_status &= ~KN_DISABLED;
852 if ((kn->kn_status & KN_ACTIVE) &&
853 ((kn->kn_status & KN_QUEUED) == 0))
858 lwkt_reltoken(&kq_token);
865 * Block as necessary until the target time is reached.
866 * If tsp is NULL we block indefinitely. If tsp->ts_secs/nsecs are both
867 * 0 we do not block at all.
870 kqueue_sleep(struct kqueue *kq, struct timespec *tsp)
875 kq->kq_state |= KQ_SLEEP;
876 error = tsleep(kq, PCATCH, "kqread", 0);
877 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) {
881 struct timespec atx = *tsp;
885 timespecsub(&atx, &ats);
886 if (ats.tv_sec < 0) {
889 timeout = atx.tv_sec > 24 * 60 * 60 ?
890 24 * 60 * 60 * hz : tstohz_high(&atx);
891 kq->kq_state |= KQ_SLEEP;
892 error = tsleep(kq, PCATCH, "kqread", timeout);
896 /* don't restart after signals... */
897 if (error == ERESTART)
904 * Scan the kqueue, return the number of active events placed in kevp up
907 * Continuous mode events may get recycled, do not continue scanning past
908 * marker unless no events have been collected.
911 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count,
912 struct knote *marker)
914 struct knote *kn, local_marker;
918 local_marker.kn_filter = EVFILT_MARKER;
923 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe);
925 kn = TAILQ_NEXT(&local_marker, kn_tqe);
926 if (kn->kn_filter == EVFILT_MARKER) {
927 /* Marker reached, we are done */
931 /* Move local marker past some other threads marker */
932 kn = TAILQ_NEXT(kn, kn_tqe);
933 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
934 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe);
939 * Remove the event for processing.
941 * WARNING! We must leave KN_QUEUED set to prevent the
942 * event from being KNOTE()d again while we
943 * potentially block in the filter function.
945 * This protects the knote from everything except
948 * WARNING! KN_PROCESSING is meant to handle any cases
949 * that leaving KN_QUEUED set does not.
951 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
953 kn->kn_status |= KN_PROCESSING;
956 * Even though close/dup2 will clean out pending knotes this
957 * code is MPSAFE and it is possible to race a close inbetween
958 * the removal of its descriptor and the clearing out of the
961 * In this case we must ensure that the knote is not queued
962 * to knpend or we risk an infinite kernel loop calling
963 * kscan, because the select/poll code will not be able to
966 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) &&
967 checkfdclosed(kq->kq_fdp, kn->kn_kevent.ident, kn->kn_fp)) {
968 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE |
974 * If disabled we ensure the event is not queued but leave
975 * its active bit set. On re-enablement the event may be
976 * immediately triggered.
978 if (kn->kn_status & KN_DISABLED) {
979 kn->kn_status &= ~(KN_QUEUED | KN_PROCESSING);
984 * If not running in one-shot mode and the event is no
985 * longer present we ensure it is removed from the queue and
988 if ((kn->kn_flags & EV_ONESHOT) == 0 &&
989 filter_event(kn, 0) == 0) {
990 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE |
995 *kevp++ = kn->kn_kevent;
1000 * Post-event action on the note
1002 if (kn->kn_flags & EV_ONESHOT) {
1003 kn->kn_status &= ~(KN_QUEUED | KN_PROCESSING);
1004 knote_detach_and_drop(kn);
1005 } else if (kn->kn_flags & EV_CLEAR) {
1008 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE |
1011 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1013 kn->kn_status &= ~KN_PROCESSING;
1016 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe);
1023 * This could be expanded to call kqueue_scan, if desired.
1028 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1037 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
1046 kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
1047 struct ucred *cred, struct sysmsg *msg)
1052 lwkt_gettoken(&kq_token);
1053 kq = (struct kqueue *)fp->f_data;
1058 kq->kq_state |= KQ_ASYNC;
1060 kq->kq_state &= ~KQ_ASYNC;
1064 error = fsetown(*(int *)data, &kq->kq_sigio);
1070 lwkt_reltoken(&kq_token);
1078 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred)
1080 struct kqueue *kq = (struct kqueue *)fp->f_data;
1082 bzero((void *)st, sizeof(*st));
1083 st->st_size = kq->kq_count;
1084 st->st_blksize = sizeof(struct kevent);
1085 st->st_mode = S_IFIFO;
1093 kqueue_close(struct file *fp)
1095 struct kqueue *kq = (struct kqueue *)fp->f_data;
1097 kqueue_terminate(kq);
1100 funsetown(kq->kq_sigio);
1102 kfree(kq, M_KQUEUE);
1107 kqueue_wakeup(struct kqueue *kq)
1109 if (kq->kq_state & KQ_SLEEP) {
1110 kq->kq_state &= ~KQ_SLEEP;
1113 KNOTE(&kq->kq_kqinfo.ki_note, 0);
1117 * Calls filterops f_attach function, acquiring mplock if filter is not
1118 * marked as FILTEROP_MPSAFE.
1121 filter_attach(struct knote *kn)
1125 if (!(kn->kn_fop->f_flags & FILTEROP_MPSAFE)) {
1127 ret = kn->kn_fop->f_attach(kn);
1130 ret = kn->kn_fop->f_attach(kn);
1137 * Detach the knote and drop it, destroying the knote.
1139 * Calls filterops f_detach function, acquiring mplock if filter is not
1140 * marked as FILTEROP_MPSAFE.
1142 * This can race due to the MP lock and/or locks acquired by f_detach,
1143 * so we interlock with KN_DELETING. It is also possible to race
1144 * a create for the same reason if userland tries to delete the knote
1145 * before the create is complete.
1148 knote_detach_and_drop(struct knote *kn)
1150 if (kn->kn_status & (KN_CREATING | KN_DELETING))
1152 kn->kn_status |= KN_DELETING;
1154 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) {
1155 kn->kn_fop->f_detach(kn);
1158 kn->kn_fop->f_detach(kn);
1165 * Calls filterops f_event function, acquiring mplock if filter is not
1166 * marked as FILTEROP_MPSAFE.
1168 * If the knote is in the middle of being created or deleted we cannot
1169 * safely call the filter op.
1172 filter_event(struct knote *kn, long hint)
1176 if (kn->kn_status & (KN_CREATING | KN_DELETING))
1179 if (!(kn->kn_fop->f_flags & FILTEROP_MPSAFE)) {
1181 ret = kn->kn_fop->f_event(kn, hint);
1184 ret = kn->kn_fop->f_event(kn, hint);
1191 * walk down a list of knotes, activating them if their event has triggered.
1194 knote(struct klist *list, long hint)
1198 lwkt_gettoken(&kq_token);
1199 SLIST_FOREACH(kn, list, kn_next) {
1200 if (filter_event(kn, hint))
1203 lwkt_reltoken(&kq_token);
1207 * insert knote at head of klist
1209 * Requires: kq_token
1212 knote_insert(struct klist *klist, struct knote *kn)
1214 lwkt_gettoken(&kq_token);
1215 SLIST_INSERT_HEAD(klist, kn, kn_next);
1216 lwkt_reltoken(&kq_token);
1220 * remove knote from a klist
1222 * Requires: kq_token
1225 knote_remove(struct klist *klist, struct knote *kn)
1227 lwkt_gettoken(&kq_token);
1228 SLIST_REMOVE(klist, kn, knote, kn_next);
1229 lwkt_reltoken(&kq_token);
1233 * remove all knotes from a specified klist
1236 knote_empty(struct klist *list)
1240 lwkt_gettoken(&kq_token);
1241 while ((kn = SLIST_FIRST(list)) != NULL)
1242 knote_detach_and_drop(kn);
1243 lwkt_reltoken(&kq_token);
1247 * remove all knotes referencing a specified fd
1250 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd)
1254 lwkt_gettoken(&kq_token);
1256 SLIST_FOREACH(kn, &fp->f_klist, kn_link) {
1257 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) {
1258 knote_detach_and_drop(kn);
1262 lwkt_reltoken(&kq_token);
1266 knote_attach(struct knote *kn)
1269 struct kqueue *kq = kn->kn_kq;
1271 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1272 KKASSERT(kn->kn_fp);
1273 list = &kn->kn_fp->f_klist;
1275 if (kq->kq_knhashmask == 0)
1276 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
1277 &kq->kq_knhashmask);
1278 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1280 SLIST_INSERT_HEAD(list, kn, kn_link);
1281 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink);
1282 kn->kn_status = KN_CREATING;
1286 knote_drop(struct knote *kn)
1293 if (kn->kn_fop->f_flags & FILTEROP_ISFD)
1294 list = &kn->kn_fp->f_klist;
1296 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
1298 SLIST_REMOVE(list, kn, knote, kn_link);
1299 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink);
1300 if (kn->kn_status & KN_QUEUED)
1302 if (kn->kn_fop->f_flags & FILTEROP_ISFD) {
1310 knote_enqueue(struct knote *kn)
1312 struct kqueue *kq = kn->kn_kq;
1314 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
1316 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe);
1317 kn->kn_status |= KN_QUEUED;
1321 * Send SIGIO on request (typically set up as a mailbox signal)
1323 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1)
1324 pgsigio(kq->kq_sigio, SIGIO, 0);
1330 knote_dequeue(struct knote *kn)
1332 struct kqueue *kq = kn->kn_kq;
1334 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
1335 KKASSERT((kn->kn_status & KN_PROCESSING) == 0);
1337 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe);
1338 kn->kn_status &= ~KN_QUEUED;
1345 knote_zone = zinit("KNOTE", sizeof(struct knote), 0, 0, 1);
1347 SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL)
1349 static struct knote *
1352 return ((struct knote *)zalloc(knote_zone));
1356 knote_free(struct knote *kn)
1358 zfree(knote_zone, kn);