The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_event.c

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    1 /*-
    2  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
    3  * Copyright 2004 John-Mark Gurney <jmg@FreeBSD.org>
    4  * Copyright (c) 2009 Apple, Inc.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/9.1/sys/kern/kern_event.c 225617 2011-09-16 13:58:51Z kmacy $");
   31 
   32 #include "opt_ktrace.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/capability.h>
   37 #include <sys/kernel.h>
   38 #include <sys/lock.h>
   39 #include <sys/mutex.h>
   40 #include <sys/proc.h>
   41 #include <sys/malloc.h>
   42 #include <sys/unistd.h>
   43 #include <sys/file.h>
   44 #include <sys/filedesc.h>
   45 #include <sys/filio.h>
   46 #include <sys/fcntl.h>
   47 #include <sys/kthread.h>
   48 #include <sys/selinfo.h>
   49 #include <sys/queue.h>
   50 #include <sys/event.h>
   51 #include <sys/eventvar.h>
   52 #include <sys/poll.h>
   53 #include <sys/protosw.h>
   54 #include <sys/sigio.h>
   55 #include <sys/signalvar.h>
   56 #include <sys/socket.h>
   57 #include <sys/socketvar.h>
   58 #include <sys/stat.h>
   59 #include <sys/sysctl.h>
   60 #include <sys/sysproto.h>
   61 #include <sys/syscallsubr.h>
   62 #include <sys/taskqueue.h>
   63 #include <sys/uio.h>
   64 #ifdef KTRACE
   65 #include <sys/ktrace.h>
   66 #endif
   67 
   68 #include <vm/uma.h>
   69 
   70 static MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
   71 
   72 /*
   73  * This lock is used if multiple kq locks are required.  This possibly
   74  * should be made into a per proc lock.
   75  */
   76 static struct mtx       kq_global;
   77 MTX_SYSINIT(kq_global, &kq_global, "kqueue order", MTX_DEF);
   78 #define KQ_GLOBAL_LOCK(lck, haslck)     do {    \
   79         if (!haslck)                            \
   80                 mtx_lock(lck);                  \
   81         haslck = 1;                             \
   82 } while (0)
   83 #define KQ_GLOBAL_UNLOCK(lck, haslck)   do {    \
   84         if (haslck)                             \
   85                 mtx_unlock(lck);                        \
   86         haslck = 0;                             \
   87 } while (0)
   88 
   89 TASKQUEUE_DEFINE_THREAD(kqueue);
   90 
   91 static int      kevent_copyout(void *arg, struct kevent *kevp, int count);
   92 static int      kevent_copyin(void *arg, struct kevent *kevp, int count);
   93 static int      kqueue_register(struct kqueue *kq, struct kevent *kev,
   94                     struct thread *td, int waitok);
   95 static int      kqueue_acquire(struct file *fp, struct kqueue **kqp);
   96 static void     kqueue_release(struct kqueue *kq, int locked);
   97 static int      kqueue_expand(struct kqueue *kq, struct filterops *fops,
   98                     uintptr_t ident, int waitok);
   99 static void     kqueue_task(void *arg, int pending);
  100 static int      kqueue_scan(struct kqueue *kq, int maxevents,
  101                     struct kevent_copyops *k_ops,
  102                     const struct timespec *timeout,
  103                     struct kevent *keva, struct thread *td);
  104 static void     kqueue_wakeup(struct kqueue *kq);
  105 static struct filterops *kqueue_fo_find(int filt);
  106 static void     kqueue_fo_release(int filt);
  107 
  108 static fo_rdwr_t        kqueue_read;
  109 static fo_rdwr_t        kqueue_write;
  110 static fo_truncate_t    kqueue_truncate;
  111 static fo_ioctl_t       kqueue_ioctl;
  112 static fo_poll_t        kqueue_poll;
  113 static fo_kqfilter_t    kqueue_kqfilter;
  114 static fo_stat_t        kqueue_stat;
  115 static fo_close_t       kqueue_close;
  116 
  117 static struct fileops kqueueops = {
  118         .fo_read = kqueue_read,
  119         .fo_write = kqueue_write,
  120         .fo_truncate = kqueue_truncate,
  121         .fo_ioctl = kqueue_ioctl,
  122         .fo_poll = kqueue_poll,
  123         .fo_kqfilter = kqueue_kqfilter,
  124         .fo_stat = kqueue_stat,
  125         .fo_close = kqueue_close,
  126         .fo_chmod = invfo_chmod,
  127         .fo_chown = invfo_chown,
  128 };
  129 
  130 static int      knote_attach(struct knote *kn, struct kqueue *kq);
  131 static void     knote_drop(struct knote *kn, struct thread *td);
  132 static void     knote_enqueue(struct knote *kn);
  133 static void     knote_dequeue(struct knote *kn);
  134 static void     knote_init(void);
  135 static struct   knote *knote_alloc(int waitok);
  136 static void     knote_free(struct knote *kn);
  137 
  138 static void     filt_kqdetach(struct knote *kn);
  139 static int      filt_kqueue(struct knote *kn, long hint);
  140 static int      filt_procattach(struct knote *kn);
  141 static void     filt_procdetach(struct knote *kn);
  142 static int      filt_proc(struct knote *kn, long hint);
  143 static int      filt_fileattach(struct knote *kn);
  144 static void     filt_timerexpire(void *knx);
  145 static int      filt_timerattach(struct knote *kn);
  146 static void     filt_timerdetach(struct knote *kn);
  147 static int      filt_timer(struct knote *kn, long hint);
  148 static int      filt_userattach(struct knote *kn);
  149 static void     filt_userdetach(struct knote *kn);
  150 static int      filt_user(struct knote *kn, long hint);
  151 static void     filt_usertouch(struct knote *kn, struct kevent *kev,
  152                     u_long type);
  153 
  154 static struct filterops file_filtops = {
  155         .f_isfd = 1,
  156         .f_attach = filt_fileattach,
  157 };
  158 static struct filterops kqread_filtops = {
  159         .f_isfd = 1,
  160         .f_detach = filt_kqdetach,
  161         .f_event = filt_kqueue,
  162 };
  163 /* XXX - move to kern_proc.c?  */
  164 static struct filterops proc_filtops = {
  165         .f_isfd = 0,
  166         .f_attach = filt_procattach,
  167         .f_detach = filt_procdetach,
  168         .f_event = filt_proc,
  169 };
  170 static struct filterops timer_filtops = {
  171         .f_isfd = 0,
  172         .f_attach = filt_timerattach,
  173         .f_detach = filt_timerdetach,
  174         .f_event = filt_timer,
  175 };
  176 static struct filterops user_filtops = {
  177         .f_attach = filt_userattach,
  178         .f_detach = filt_userdetach,
  179         .f_event = filt_user,
  180         .f_touch = filt_usertouch,
  181 };
  182 
  183 static uma_zone_t       knote_zone;
  184 static int              kq_ncallouts = 0;
  185 static int              kq_calloutmax = (4 * 1024);
  186 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
  187     &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
  188 
  189 /* XXX - ensure not KN_INFLUX?? */
  190 #define KNOTE_ACTIVATE(kn, islock) do {                                 \
  191         if ((islock))                                                   \
  192                 mtx_assert(&(kn)->kn_kq->kq_lock, MA_OWNED);            \
  193         else                                                            \
  194                 KQ_LOCK((kn)->kn_kq);                                   \
  195         (kn)->kn_status |= KN_ACTIVE;                                   \
  196         if (((kn)->kn_status & (KN_QUEUED | KN_DISABLED)) == 0)         \
  197                 knote_enqueue((kn));                                    \
  198         if (!(islock))                                                  \
  199                 KQ_UNLOCK((kn)->kn_kq);                                 \
  200 } while(0)
  201 #define KQ_LOCK(kq) do {                                                \
  202         mtx_lock(&(kq)->kq_lock);                                       \
  203 } while (0)
  204 #define KQ_FLUX_WAKEUP(kq) do {                                         \
  205         if (((kq)->kq_state & KQ_FLUXWAIT) == KQ_FLUXWAIT) {            \
  206                 (kq)->kq_state &= ~KQ_FLUXWAIT;                         \
  207                 wakeup((kq));                                           \
  208         }                                                               \
  209 } while (0)
  210 #define KQ_UNLOCK_FLUX(kq) do {                                         \
  211         KQ_FLUX_WAKEUP(kq);                                             \
  212         mtx_unlock(&(kq)->kq_lock);                                     \
  213 } while (0)
  214 #define KQ_UNLOCK(kq) do {                                              \
  215         mtx_unlock(&(kq)->kq_lock);                                     \
  216 } while (0)
  217 #define KQ_OWNED(kq) do {                                               \
  218         mtx_assert(&(kq)->kq_lock, MA_OWNED);                           \
  219 } while (0)
  220 #define KQ_NOTOWNED(kq) do {                                            \
  221         mtx_assert(&(kq)->kq_lock, MA_NOTOWNED);                        \
  222 } while (0)
  223 #define KN_LIST_LOCK(kn) do {                                           \
  224         if (kn->kn_knlist != NULL)                                      \
  225                 kn->kn_knlist->kl_lock(kn->kn_knlist->kl_lockarg);      \
  226 } while (0)
  227 #define KN_LIST_UNLOCK(kn) do {                                         \
  228         if (kn->kn_knlist != NULL)                                      \
  229                 kn->kn_knlist->kl_unlock(kn->kn_knlist->kl_lockarg);    \
  230 } while (0)
  231 #define KNL_ASSERT_LOCK(knl, islocked) do {                             \
  232         if (islocked)                                                   \
  233                 KNL_ASSERT_LOCKED(knl);                         \
  234         else                                                            \
  235                 KNL_ASSERT_UNLOCKED(knl);                               \
  236 } while (0)
  237 #ifdef INVARIANTS
  238 #define KNL_ASSERT_LOCKED(knl) do {                                     \
  239         knl->kl_assert_locked((knl)->kl_lockarg);                       \
  240 } while (0)
  241 #define KNL_ASSERT_UNLOCKED(knl) do {                                   \
  242         knl->kl_assert_unlocked((knl)->kl_lockarg);                     \
  243 } while (0)
  244 #else /* !INVARIANTS */
  245 #define KNL_ASSERT_LOCKED(knl) do {} while(0)
  246 #define KNL_ASSERT_UNLOCKED(knl) do {} while (0)
  247 #endif /* INVARIANTS */
  248 
  249 #define KN_HASHSIZE             64              /* XXX should be tunable */
  250 #define KN_HASH(val, mask)      (((val) ^ (val >> 8)) & (mask))
  251 
  252 static int
  253 filt_nullattach(struct knote *kn)
  254 {
  255 
  256         return (ENXIO);
  257 };
  258 
  259 struct filterops null_filtops = {
  260         .f_isfd = 0,
  261         .f_attach = filt_nullattach,
  262 };
  263 
  264 /* XXX - make SYSINIT to add these, and move into respective modules. */
  265 extern struct filterops sig_filtops;
  266 extern struct filterops fs_filtops;
  267 
  268 /*
  269  * Table for for all system-defined filters.
  270  */
  271 static struct mtx       filterops_lock;
  272 MTX_SYSINIT(kqueue_filterops, &filterops_lock, "protect sysfilt_ops",
  273         MTX_DEF);
  274 static struct {
  275         struct filterops *for_fop;
  276         int for_refcnt;
  277 } sysfilt_ops[EVFILT_SYSCOUNT] = {
  278         { &file_filtops },                      /* EVFILT_READ */
  279         { &file_filtops },                      /* EVFILT_WRITE */
  280         { &null_filtops },                      /* EVFILT_AIO */
  281         { &file_filtops },                      /* EVFILT_VNODE */
  282         { &proc_filtops },                      /* EVFILT_PROC */
  283         { &sig_filtops },                       /* EVFILT_SIGNAL */
  284         { &timer_filtops },                     /* EVFILT_TIMER */
  285         { &null_filtops },                      /* former EVFILT_NETDEV */
  286         { &fs_filtops },                        /* EVFILT_FS */
  287         { &null_filtops },                      /* EVFILT_LIO */
  288         { &user_filtops },                      /* EVFILT_USER */
  289 };
  290 
  291 /*
  292  * Simple redirection for all cdevsw style objects to call their fo_kqfilter
  293  * method.
  294  */
  295 static int
  296 filt_fileattach(struct knote *kn)
  297 {
  298 
  299         return (fo_kqfilter(kn->kn_fp, kn));
  300 }
  301 
  302 /*ARGSUSED*/
  303 static int
  304 kqueue_kqfilter(struct file *fp, struct knote *kn)
  305 {
  306         struct kqueue *kq = kn->kn_fp->f_data;
  307 
  308         if (kn->kn_filter != EVFILT_READ)
  309                 return (EINVAL);
  310 
  311         kn->kn_status |= KN_KQUEUE;
  312         kn->kn_fop = &kqread_filtops;
  313         knlist_add(&kq->kq_sel.si_note, kn, 0);
  314 
  315         return (0);
  316 }
  317 
  318 static void
  319 filt_kqdetach(struct knote *kn)
  320 {
  321         struct kqueue *kq = kn->kn_fp->f_data;
  322 
  323         knlist_remove(&kq->kq_sel.si_note, kn, 0);
  324 }
  325 
  326 /*ARGSUSED*/
  327 static int
  328 filt_kqueue(struct knote *kn, long hint)
  329 {
  330         struct kqueue *kq = kn->kn_fp->f_data;
  331 
  332         kn->kn_data = kq->kq_count;
  333         return (kn->kn_data > 0);
  334 }
  335 
  336 /* XXX - move to kern_proc.c?  */
  337 static int
  338 filt_procattach(struct knote *kn)
  339 {
  340         struct proc *p;
  341         int immediate;
  342         int error;
  343 
  344         immediate = 0;
  345         p = pfind(kn->kn_id);
  346         if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
  347                 p = zpfind(kn->kn_id);
  348                 immediate = 1;
  349         } else if (p != NULL && (p->p_flag & P_WEXIT)) {
  350                 immediate = 1;
  351         }
  352 
  353         if (p == NULL)
  354                 return (ESRCH);
  355         if ((error = p_cansee(curthread, p))) {
  356                 PROC_UNLOCK(p);
  357                 return (error);
  358         }
  359 
  360         kn->kn_ptr.p_proc = p;
  361         kn->kn_flags |= EV_CLEAR;               /* automatically set */
  362 
  363         /*
  364          * internal flag indicating registration done by kernel
  365          */
  366         if (kn->kn_flags & EV_FLAG1) {
  367                 kn->kn_data = kn->kn_sdata;             /* ppid */
  368                 kn->kn_fflags = NOTE_CHILD;
  369                 kn->kn_flags &= ~EV_FLAG1;
  370         }
  371 
  372         if (immediate == 0)
  373                 knlist_add(&p->p_klist, kn, 1);
  374 
  375         /*
  376          * Immediately activate any exit notes if the target process is a
  377          * zombie.  This is necessary to handle the case where the target
  378          * process, e.g. a child, dies before the kevent is registered.
  379          */
  380         if (immediate && filt_proc(kn, NOTE_EXIT))
  381                 KNOTE_ACTIVATE(kn, 0);
  382 
  383         PROC_UNLOCK(p);
  384 
  385         return (0);
  386 }
  387 
  388 /*
  389  * The knote may be attached to a different process, which may exit,
  390  * leaving nothing for the knote to be attached to.  So when the process
  391  * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
  392  * it will be deleted when read out.  However, as part of the knote deletion,
  393  * this routine is called, so a check is needed to avoid actually performing
  394  * a detach, because the original process does not exist any more.
  395  */
  396 /* XXX - move to kern_proc.c?  */
  397 static void
  398 filt_procdetach(struct knote *kn)
  399 {
  400         struct proc *p;
  401 
  402         p = kn->kn_ptr.p_proc;
  403         knlist_remove(&p->p_klist, kn, 0);
  404         kn->kn_ptr.p_proc = NULL;
  405 }
  406 
  407 /* XXX - move to kern_proc.c?  */
  408 static int
  409 filt_proc(struct knote *kn, long hint)
  410 {
  411         struct proc *p = kn->kn_ptr.p_proc;
  412         u_int event;
  413 
  414         /*
  415          * mask off extra data
  416          */
  417         event = (u_int)hint & NOTE_PCTRLMASK;
  418 
  419         /*
  420          * if the user is interested in this event, record it.
  421          */
  422         if (kn->kn_sfflags & event)
  423                 kn->kn_fflags |= event;
  424 
  425         /*
  426          * process is gone, so flag the event as finished.
  427          */
  428         if (event == NOTE_EXIT) {
  429                 if (!(kn->kn_status & KN_DETACHED))
  430                         knlist_remove_inevent(&p->p_klist, kn);
  431                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
  432                 kn->kn_data = p->p_xstat;
  433                 kn->kn_ptr.p_proc = NULL;
  434                 return (1);
  435         }
  436 
  437         return (kn->kn_fflags != 0);
  438 }
  439 
  440 /*
  441  * Called when the process forked. It mostly does the same as the
  442  * knote(), activating all knotes registered to be activated when the
  443  * process forked. Additionally, for each knote attached to the
  444  * parent, check whether user wants to track the new process. If so
  445  * attach a new knote to it, and immediately report an event with the
  446  * child's pid.
  447  */
  448 void
  449 knote_fork(struct knlist *list, int pid)
  450 {
  451         struct kqueue *kq;
  452         struct knote *kn;
  453         struct kevent kev;
  454         int error;
  455 
  456         if (list == NULL)
  457                 return;
  458         list->kl_lock(list->kl_lockarg);
  459 
  460         SLIST_FOREACH(kn, &list->kl_list, kn_selnext) {
  461                 if ((kn->kn_status & KN_INFLUX) == KN_INFLUX)
  462                         continue;
  463                 kq = kn->kn_kq;
  464                 KQ_LOCK(kq);
  465                 if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
  466                         KQ_UNLOCK(kq);
  467                         continue;
  468                 }
  469 
  470                 /*
  471                  * The same as knote(), activate the event.
  472                  */
  473                 if ((kn->kn_sfflags & NOTE_TRACK) == 0) {
  474                         kn->kn_status |= KN_HASKQLOCK;
  475                         if (kn->kn_fop->f_event(kn, NOTE_FORK | pid))
  476                                 KNOTE_ACTIVATE(kn, 1);
  477                         kn->kn_status &= ~KN_HASKQLOCK;
  478                         KQ_UNLOCK(kq);
  479                         continue;
  480                 }
  481 
  482                 /*
  483                  * The NOTE_TRACK case. In addition to the activation
  484                  * of the event, we need to register new event to
  485                  * track the child. Drop the locks in preparation for
  486                  * the call to kqueue_register().
  487                  */
  488                 kn->kn_status |= KN_INFLUX;
  489                 KQ_UNLOCK(kq);
  490                 list->kl_unlock(list->kl_lockarg);
  491 
  492                 /*
  493                  * Activate existing knote and register a knote with
  494                  * new process.
  495                  */
  496                 kev.ident = pid;
  497                 kev.filter = kn->kn_filter;
  498                 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
  499                 kev.fflags = kn->kn_sfflags;
  500                 kev.data = kn->kn_id;           /* parent */
  501                 kev.udata = kn->kn_kevent.udata;/* preserve udata */
  502                 error = kqueue_register(kq, &kev, NULL, 0);
  503                 if (kn->kn_fop->f_event(kn, NOTE_FORK | pid))
  504                         KNOTE_ACTIVATE(kn, 0);
  505                 if (error)
  506                         kn->kn_fflags |= NOTE_TRACKERR;
  507                 KQ_LOCK(kq);
  508                 kn->kn_status &= ~KN_INFLUX;
  509                 KQ_UNLOCK_FLUX(kq);
  510                 list->kl_lock(list->kl_lockarg);
  511         }
  512         list->kl_unlock(list->kl_lockarg);
  513 }
  514 
  515 static int
  516 timertoticks(intptr_t data)
  517 {
  518         struct timeval tv;
  519         int tticks;
  520 
  521         tv.tv_sec = data / 1000;
  522         tv.tv_usec = (data % 1000) * 1000;
  523         tticks = tvtohz(&tv);
  524 
  525         return tticks;
  526 }
  527 
  528 /* XXX - move to kern_timeout.c? */
  529 static void
  530 filt_timerexpire(void *knx)
  531 {
  532         struct knote *kn = knx;
  533         struct callout *calloutp;
  534 
  535         kn->kn_data++;
  536         KNOTE_ACTIVATE(kn, 0);  /* XXX - handle locking */
  537 
  538         if ((kn->kn_flags & EV_ONESHOT) != EV_ONESHOT) {
  539                 calloutp = (struct callout *)kn->kn_hook;
  540                 callout_reset_curcpu(calloutp, timertoticks(kn->kn_sdata),
  541                     filt_timerexpire, kn);
  542         }
  543 }
  544 
  545 /*
  546  * data contains amount of time to sleep, in milliseconds
  547  */
  548 /* XXX - move to kern_timeout.c? */
  549 static int
  550 filt_timerattach(struct knote *kn)
  551 {
  552         struct callout *calloutp;
  553 
  554         atomic_add_int(&kq_ncallouts, 1);
  555 
  556         if (kq_ncallouts >= kq_calloutmax) {
  557                 atomic_add_int(&kq_ncallouts, -1);
  558                 return (ENOMEM);
  559         }
  560 
  561         kn->kn_flags |= EV_CLEAR;               /* automatically set */
  562         kn->kn_status &= ~KN_DETACHED;          /* knlist_add usually sets it */
  563         calloutp = malloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
  564         callout_init(calloutp, CALLOUT_MPSAFE);
  565         kn->kn_hook = calloutp;
  566         callout_reset_curcpu(calloutp, timertoticks(kn->kn_sdata),
  567             filt_timerexpire, kn);
  568 
  569         return (0);
  570 }
  571 
  572 /* XXX - move to kern_timeout.c? */
  573 static void
  574 filt_timerdetach(struct knote *kn)
  575 {
  576         struct callout *calloutp;
  577 
  578         calloutp = (struct callout *)kn->kn_hook;
  579         callout_drain(calloutp);
  580         free(calloutp, M_KQUEUE);
  581         atomic_add_int(&kq_ncallouts, -1);
  582         kn->kn_status |= KN_DETACHED;   /* knlist_remove usually clears it */
  583 }
  584 
  585 /* XXX - move to kern_timeout.c? */
  586 static int
  587 filt_timer(struct knote *kn, long hint)
  588 {
  589 
  590         return (kn->kn_data != 0);
  591 }
  592 
  593 static int
  594 filt_userattach(struct knote *kn)
  595 {
  596 
  597         /* 
  598          * EVFILT_USER knotes are not attached to anything in the kernel.
  599          */ 
  600         kn->kn_hook = NULL;
  601         if (kn->kn_fflags & NOTE_TRIGGER)
  602                 kn->kn_hookid = 1;
  603         else
  604                 kn->kn_hookid = 0;
  605         return (0);
  606 }
  607 
  608 static void
  609 filt_userdetach(__unused struct knote *kn)
  610 {
  611 
  612         /*
  613          * EVFILT_USER knotes are not attached to anything in the kernel.
  614          */
  615 }
  616 
  617 static int
  618 filt_user(struct knote *kn, __unused long hint)
  619 {
  620 
  621         return (kn->kn_hookid);
  622 }
  623 
  624 static void
  625 filt_usertouch(struct knote *kn, struct kevent *kev, u_long type)
  626 {
  627         u_int ffctrl;
  628 
  629         switch (type) {
  630         case EVENT_REGISTER:
  631                 if (kev->fflags & NOTE_TRIGGER)
  632                         kn->kn_hookid = 1;
  633 
  634                 ffctrl = kev->fflags & NOTE_FFCTRLMASK;
  635                 kev->fflags &= NOTE_FFLAGSMASK;
  636                 switch (ffctrl) {
  637                 case NOTE_FFNOP:
  638                         break;
  639 
  640                 case NOTE_FFAND:
  641                         kn->kn_sfflags &= kev->fflags;
  642                         break;
  643 
  644                 case NOTE_FFOR:
  645                         kn->kn_sfflags |= kev->fflags;
  646                         break;
  647 
  648                 case NOTE_FFCOPY:
  649                         kn->kn_sfflags = kev->fflags;
  650                         break;
  651 
  652                 default:
  653                         /* XXX Return error? */
  654                         break;
  655                 }
  656                 kn->kn_sdata = kev->data;
  657                 if (kev->flags & EV_CLEAR) {
  658                         kn->kn_hookid = 0;
  659                         kn->kn_data = 0;
  660                         kn->kn_fflags = 0;
  661                 }
  662                 break;
  663 
  664         case EVENT_PROCESS:
  665                 *kev = kn->kn_kevent;
  666                 kev->fflags = kn->kn_sfflags;
  667                 kev->data = kn->kn_sdata;
  668                 if (kn->kn_flags & EV_CLEAR) {
  669                         kn->kn_hookid = 0;
  670                         kn->kn_data = 0;
  671                         kn->kn_fflags = 0;
  672                 }
  673                 break;
  674 
  675         default:
  676                 panic("filt_usertouch() - invalid type (%ld)", type);
  677                 break;
  678         }
  679 }
  680 
  681 int
  682 sys_kqueue(struct thread *td, struct kqueue_args *uap)
  683 {
  684         struct filedesc *fdp;
  685         struct kqueue *kq;
  686         struct file *fp;
  687         int fd, error;
  688 
  689         fdp = td->td_proc->p_fd;
  690         error = falloc(td, &fp, &fd, 0);
  691         if (error)
  692                 goto done2;
  693 
  694         /* An extra reference on `nfp' has been held for us by falloc(). */
  695         kq = malloc(sizeof *kq, M_KQUEUE, M_WAITOK | M_ZERO);
  696         mtx_init(&kq->kq_lock, "kqueue", NULL, MTX_DEF|MTX_DUPOK);
  697         TAILQ_INIT(&kq->kq_head);
  698         kq->kq_fdp = fdp;
  699         knlist_init_mtx(&kq->kq_sel.si_note, &kq->kq_lock);
  700         TASK_INIT(&kq->kq_task, 0, kqueue_task, kq);
  701 
  702         FILEDESC_XLOCK(fdp);
  703         SLIST_INSERT_HEAD(&fdp->fd_kqlist, kq, kq_list);
  704         FILEDESC_XUNLOCK(fdp);
  705 
  706         finit(fp, FREAD | FWRITE, DTYPE_KQUEUE, kq, &kqueueops);
  707         fdrop(fp, td);
  708 
  709         td->td_retval[0] = fd;
  710 done2:
  711         return (error);
  712 }
  713 
  714 #ifndef _SYS_SYSPROTO_H_
  715 struct kevent_args {
  716         int     fd;
  717         const struct kevent *changelist;
  718         int     nchanges;
  719         struct  kevent *eventlist;
  720         int     nevents;
  721         const struct timespec *timeout;
  722 };
  723 #endif
  724 int
  725 sys_kevent(struct thread *td, struct kevent_args *uap)
  726 {
  727         struct timespec ts, *tsp;
  728         struct kevent_copyops k_ops = { uap,
  729                                         kevent_copyout,
  730                                         kevent_copyin};
  731         int error;
  732 #ifdef KTRACE
  733         struct uio ktruio;
  734         struct iovec ktriov;
  735         struct uio *ktruioin = NULL;
  736         struct uio *ktruioout = NULL;
  737 #endif
  738 
  739         if (uap->timeout != NULL) {
  740                 error = copyin(uap->timeout, &ts, sizeof(ts));
  741                 if (error)
  742                         return (error);
  743                 tsp = &ts;
  744         } else
  745                 tsp = NULL;
  746 
  747 #ifdef KTRACE
  748         if (KTRPOINT(td, KTR_GENIO)) {
  749                 ktriov.iov_base = uap->changelist;
  750                 ktriov.iov_len = uap->nchanges * sizeof(struct kevent);
  751                 ktruio = (struct uio){ .uio_iov = &ktriov, .uio_iovcnt = 1,
  752                     .uio_segflg = UIO_USERSPACE, .uio_rw = UIO_READ,
  753                     .uio_td = td };
  754                 ktruioin = cloneuio(&ktruio);
  755                 ktriov.iov_base = uap->eventlist;
  756                 ktriov.iov_len = uap->nevents * sizeof(struct kevent);
  757                 ktruioout = cloneuio(&ktruio);
  758         }
  759 #endif
  760 
  761         error = kern_kevent(td, uap->fd, uap->nchanges, uap->nevents,
  762             &k_ops, tsp);
  763 
  764 #ifdef KTRACE
  765         if (ktruioin != NULL) {
  766                 ktruioin->uio_resid = uap->nchanges * sizeof(struct kevent);
  767                 ktrgenio(uap->fd, UIO_WRITE, ktruioin, 0);
  768                 ktruioout->uio_resid = td->td_retval[0] * sizeof(struct kevent);
  769                 ktrgenio(uap->fd, UIO_READ, ktruioout, error);
  770         }
  771 #endif
  772 
  773         return (error);
  774 }
  775 
  776 /*
  777  * Copy 'count' items into the destination list pointed to by uap->eventlist.
  778  */
  779 static int
  780 kevent_copyout(void *arg, struct kevent *kevp, int count)
  781 {
  782         struct kevent_args *uap;
  783         int error;
  784 
  785         KASSERT(count <= KQ_NEVENTS, ("count (%d) > KQ_NEVENTS", count));
  786         uap = (struct kevent_args *)arg;
  787 
  788         error = copyout(kevp, uap->eventlist, count * sizeof *kevp);
  789         if (error == 0)
  790                 uap->eventlist += count;
  791         return (error);
  792 }
  793 
  794 /*
  795  * Copy 'count' items from the list pointed to by uap->changelist.
  796  */
  797 static int
  798 kevent_copyin(void *arg, struct kevent *kevp, int count)
  799 {
  800         struct kevent_args *uap;
  801         int error;
  802 
  803         KASSERT(count <= KQ_NEVENTS, ("count (%d) > KQ_NEVENTS", count));
  804         uap = (struct kevent_args *)arg;
  805 
  806         error = copyin(uap->changelist, kevp, count * sizeof *kevp);
  807         if (error == 0)
  808                 uap->changelist += count;
  809         return (error);
  810 }
  811 
  812 int
  813 kern_kevent(struct thread *td, int fd, int nchanges, int nevents,
  814     struct kevent_copyops *k_ops, const struct timespec *timeout)
  815 {
  816         struct kevent keva[KQ_NEVENTS];
  817         struct kevent *kevp, *changes;
  818         struct kqueue *kq;
  819         struct file *fp;
  820         int i, n, nerrors, error;
  821 
  822         if ((error = fget(td, fd, CAP_POST_EVENT, &fp)) != 0)
  823                 return (error);
  824         if ((error = kqueue_acquire(fp, &kq)) != 0)
  825                 goto done_norel;
  826 
  827         nerrors = 0;
  828 
  829         while (nchanges > 0) {
  830                 n = nchanges > KQ_NEVENTS ? KQ_NEVENTS : nchanges;
  831                 error = k_ops->k_copyin(k_ops->arg, keva, n);
  832                 if (error)
  833                         goto done;
  834                 changes = keva;
  835                 for (i = 0; i < n; i++) {
  836                         kevp = &changes[i];
  837                         if (!kevp->filter)
  838                                 continue;
  839                         kevp->flags &= ~EV_SYSFLAGS;
  840                         error = kqueue_register(kq, kevp, td, 1);
  841                         if (error || (kevp->flags & EV_RECEIPT)) {
  842                                 if (nevents != 0) {
  843                                         kevp->flags = EV_ERROR;
  844                                         kevp->data = error;
  845                                         (void) k_ops->k_copyout(k_ops->arg,
  846                                             kevp, 1);
  847                                         nevents--;
  848                                         nerrors++;
  849                                 } else {
  850                                         goto done;
  851                                 }
  852                         }
  853                 }
  854                 nchanges -= n;
  855         }
  856         if (nerrors) {
  857                 td->td_retval[0] = nerrors;
  858                 error = 0;
  859                 goto done;
  860         }
  861 
  862         error = kqueue_scan(kq, nevents, k_ops, timeout, keva, td);
  863 done:
  864         kqueue_release(kq, 0);
  865 done_norel:
  866         fdrop(fp, td);
  867         return (error);
  868 }
  869 
  870 int
  871 kqueue_add_filteropts(int filt, struct filterops *filtops)
  872 {
  873         int error;
  874 
  875         error = 0;
  876         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0) {
  877                 printf(
  878 "trying to add a filterop that is out of range: %d is beyond %d\n",
  879                     ~filt, EVFILT_SYSCOUNT);
  880                 return EINVAL;
  881         }
  882         mtx_lock(&filterops_lock);
  883         if (sysfilt_ops[~filt].for_fop != &null_filtops &&
  884             sysfilt_ops[~filt].for_fop != NULL)
  885                 error = EEXIST;
  886         else {
  887                 sysfilt_ops[~filt].for_fop = filtops;
  888                 sysfilt_ops[~filt].for_refcnt = 0;
  889         }
  890         mtx_unlock(&filterops_lock);
  891 
  892         return (error);
  893 }
  894 
  895 int
  896 kqueue_del_filteropts(int filt)
  897 {
  898         int error;
  899 
  900         error = 0;
  901         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  902                 return EINVAL;
  903 
  904         mtx_lock(&filterops_lock);
  905         if (sysfilt_ops[~filt].for_fop == &null_filtops ||
  906             sysfilt_ops[~filt].for_fop == NULL)
  907                 error = EINVAL;
  908         else if (sysfilt_ops[~filt].for_refcnt != 0)
  909                 error = EBUSY;
  910         else {
  911                 sysfilt_ops[~filt].for_fop = &null_filtops;
  912                 sysfilt_ops[~filt].for_refcnt = 0;
  913         }
  914         mtx_unlock(&filterops_lock);
  915 
  916         return error;
  917 }
  918 
  919 static struct filterops *
  920 kqueue_fo_find(int filt)
  921 {
  922 
  923         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  924                 return NULL;
  925 
  926         mtx_lock(&filterops_lock);
  927         sysfilt_ops[~filt].for_refcnt++;
  928         if (sysfilt_ops[~filt].for_fop == NULL)
  929                 sysfilt_ops[~filt].for_fop = &null_filtops;
  930         mtx_unlock(&filterops_lock);
  931 
  932         return sysfilt_ops[~filt].for_fop;
  933 }
  934 
  935 static void
  936 kqueue_fo_release(int filt)
  937 {
  938 
  939         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  940                 return;
  941 
  942         mtx_lock(&filterops_lock);
  943         KASSERT(sysfilt_ops[~filt].for_refcnt > 0,
  944             ("filter object refcount not valid on release"));
  945         sysfilt_ops[~filt].for_refcnt--;
  946         mtx_unlock(&filterops_lock);
  947 }
  948 
  949 /*
  950  * A ref to kq (obtained via kqueue_acquire) must be held.  waitok will
  951  * influence if memory allocation should wait.  Make sure it is 0 if you
  952  * hold any mutexes.
  953  */
  954 static int
  955 kqueue_register(struct kqueue *kq, struct kevent *kev, struct thread *td, int waitok)
  956 {
  957         struct filterops *fops;
  958         struct file *fp;
  959         struct knote *kn, *tkn;
  960         int error, filt, event;
  961         int haskqglobal;
  962 
  963         fp = NULL;
  964         kn = NULL;
  965         error = 0;
  966         haskqglobal = 0;
  967 
  968         filt = kev->filter;
  969         fops = kqueue_fo_find(filt);
  970         if (fops == NULL)
  971                 return EINVAL;
  972 
  973         tkn = knote_alloc(waitok);              /* prevent waiting with locks */
  974 
  975 findkn:
  976         if (fops->f_isfd) {
  977                 KASSERT(td != NULL, ("td is NULL"));
  978                 error = fget(td, kev->ident, CAP_POLL_EVENT, &fp);
  979                 if (error)
  980                         goto done;
  981 
  982                 if ((kev->flags & EV_ADD) == EV_ADD && kqueue_expand(kq, fops,
  983                     kev->ident, 0) != 0) {
  984                         /* try again */
  985                         fdrop(fp, td);
  986                         fp = NULL;
  987                         error = kqueue_expand(kq, fops, kev->ident, waitok);
  988                         if (error)
  989                                 goto done;
  990                         goto findkn;
  991                 }
  992 
  993                 if (fp->f_type == DTYPE_KQUEUE) {
  994                         /*
  995                          * if we add some inteligence about what we are doing,
  996                          * we should be able to support events on ourselves.
  997                          * We need to know when we are doing this to prevent
  998                          * getting both the knlist lock and the kq lock since
  999                          * they are the same thing.
 1000                          */
 1001                         if (fp->f_data == kq) {
 1002                                 error = EINVAL;
 1003                                 goto done;
 1004                         }
 1005 
 1006                         KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1007                 }
 1008 
 1009                 KQ_LOCK(kq);
 1010                 if (kev->ident < kq->kq_knlistsize) {
 1011                         SLIST_FOREACH(kn, &kq->kq_knlist[kev->ident], kn_link)
 1012                                 if (kev->filter == kn->kn_filter)
 1013                                         break;
 1014                 }
 1015         } else {
 1016                 if ((kev->flags & EV_ADD) == EV_ADD)
 1017                         kqueue_expand(kq, fops, kev->ident, waitok);
 1018 
 1019                 KQ_LOCK(kq);
 1020                 if (kq->kq_knhashmask != 0) {
 1021                         struct klist *list;
 1022 
 1023                         list = &kq->kq_knhash[
 1024                             KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
 1025                         SLIST_FOREACH(kn, list, kn_link)
 1026                                 if (kev->ident == kn->kn_id &&
 1027                                     kev->filter == kn->kn_filter)
 1028                                         break;
 1029                 }
 1030         }
 1031 
 1032         /* knote is in the process of changing, wait for it to stablize. */
 1033         if (kn != NULL && (kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1034                 KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1035                 kq->kq_state |= KQ_FLUXWAIT;
 1036                 msleep(kq, &kq->kq_lock, PSOCK | PDROP, "kqflxwt", 0);
 1037                 if (fp != NULL) {
 1038                         fdrop(fp, td);
 1039                         fp = NULL;
 1040                 }
 1041                 goto findkn;
 1042         }
 1043 
 1044         /*
 1045          * kn now contains the matching knote, or NULL if no match
 1046          */
 1047         if (kn == NULL) {
 1048                 if (kev->flags & EV_ADD) {
 1049                         kn = tkn;
 1050                         tkn = NULL;
 1051                         if (kn == NULL) {
 1052                                 KQ_UNLOCK(kq);
 1053                                 error = ENOMEM;
 1054                                 goto done;
 1055                         }
 1056                         kn->kn_fp = fp;
 1057                         kn->kn_kq = kq;
 1058                         kn->kn_fop = fops;
 1059                         /*
 1060                          * apply reference counts to knote structure, and
 1061                          * do not release it at the end of this routine.
 1062                          */
 1063                         fops = NULL;
 1064                         fp = NULL;
 1065 
 1066                         kn->kn_sfflags = kev->fflags;
 1067                         kn->kn_sdata = kev->data;
 1068                         kev->fflags = 0;
 1069                         kev->data = 0;
 1070                         kn->kn_kevent = *kev;
 1071                         kn->kn_kevent.flags &= ~(EV_ADD | EV_DELETE |
 1072                             EV_ENABLE | EV_DISABLE);
 1073                         kn->kn_status = KN_INFLUX|KN_DETACHED;
 1074 
 1075                         error = knote_attach(kn, kq);
 1076                         KQ_UNLOCK(kq);
 1077                         if (error != 0) {
 1078                                 tkn = kn;
 1079                                 goto done;
 1080                         }
 1081 
 1082                         if ((error = kn->kn_fop->f_attach(kn)) != 0) {
 1083                                 knote_drop(kn, td);
 1084                                 goto done;
 1085                         }
 1086                         KN_LIST_LOCK(kn);
 1087                         goto done_ev_add;
 1088                 } else {
 1089                         /* No matching knote and the EV_ADD flag is not set. */
 1090                         KQ_UNLOCK(kq);
 1091                         error = ENOENT;
 1092                         goto done;
 1093                 }
 1094         }
 1095         
 1096         if (kev->flags & EV_DELETE) {
 1097                 kn->kn_status |= KN_INFLUX;
 1098                 KQ_UNLOCK(kq);
 1099                 if (!(kn->kn_status & KN_DETACHED))
 1100                         kn->kn_fop->f_detach(kn);
 1101                 knote_drop(kn, td);
 1102                 goto done;
 1103         }
 1104 
 1105         /*
 1106          * The user may change some filter values after the initial EV_ADD,
 1107          * but doing so will not reset any filter which has already been
 1108          * triggered.
 1109          */
 1110         kn->kn_status |= KN_INFLUX;
 1111         KQ_UNLOCK(kq);
 1112         KN_LIST_LOCK(kn);
 1113         kn->kn_kevent.udata = kev->udata;
 1114         if (!fops->f_isfd && fops->f_touch != NULL) {
 1115                 fops->f_touch(kn, kev, EVENT_REGISTER);
 1116         } else {
 1117                 kn->kn_sfflags = kev->fflags;
 1118                 kn->kn_sdata = kev->data;
 1119         }
 1120 
 1121         /*
 1122          * We can get here with kn->kn_knlist == NULL.  This can happen when
 1123          * the initial attach event decides that the event is "completed" 
 1124          * already.  i.e. filt_procattach is called on a zombie process.  It
 1125          * will call filt_proc which will remove it from the list, and NULL
 1126          * kn_knlist.
 1127          */
 1128 done_ev_add:
 1129         event = kn->kn_fop->f_event(kn, 0);
 1130         KQ_LOCK(kq);
 1131         if (event)
 1132                 KNOTE_ACTIVATE(kn, 1);
 1133         kn->kn_status &= ~KN_INFLUX;
 1134         KN_LIST_UNLOCK(kn);
 1135 
 1136         if ((kev->flags & EV_DISABLE) &&
 1137             ((kn->kn_status & KN_DISABLED) == 0)) {
 1138                 kn->kn_status |= KN_DISABLED;
 1139         }
 1140 
 1141         if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
 1142                 kn->kn_status &= ~KN_DISABLED;
 1143                 if ((kn->kn_status & KN_ACTIVE) &&
 1144                     ((kn->kn_status & KN_QUEUED) == 0))
 1145                         knote_enqueue(kn);
 1146         }
 1147         KQ_UNLOCK_FLUX(kq);
 1148 
 1149 done:
 1150         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1151         if (fp != NULL)
 1152                 fdrop(fp, td);
 1153         if (tkn != NULL)
 1154                 knote_free(tkn);
 1155         if (fops != NULL)
 1156                 kqueue_fo_release(filt);
 1157         return (error);
 1158 }
 1159 
 1160 static int
 1161 kqueue_acquire(struct file *fp, struct kqueue **kqp)
 1162 {
 1163         int error;
 1164         struct kqueue *kq;
 1165 
 1166         error = 0;
 1167 
 1168         kq = fp->f_data;
 1169         if (fp->f_type != DTYPE_KQUEUE || kq == NULL)
 1170                 return (EBADF);
 1171         *kqp = kq;
 1172         KQ_LOCK(kq);
 1173         if ((kq->kq_state & KQ_CLOSING) == KQ_CLOSING) {
 1174                 KQ_UNLOCK(kq);
 1175                 return (EBADF);
 1176         }
 1177         kq->kq_refcnt++;
 1178         KQ_UNLOCK(kq);
 1179 
 1180         return error;
 1181 }
 1182 
 1183 static void
 1184 kqueue_release(struct kqueue *kq, int locked)
 1185 {
 1186         if (locked)
 1187                 KQ_OWNED(kq);
 1188         else
 1189                 KQ_LOCK(kq);
 1190         kq->kq_refcnt--;
 1191         if (kq->kq_refcnt == 1)
 1192                 wakeup(&kq->kq_refcnt);
 1193         if (!locked)
 1194                 KQ_UNLOCK(kq);
 1195 }
 1196 
 1197 static void
 1198 kqueue_schedtask(struct kqueue *kq)
 1199 {
 1200 
 1201         KQ_OWNED(kq);
 1202         KASSERT(((kq->kq_state & KQ_TASKDRAIN) != KQ_TASKDRAIN),
 1203             ("scheduling kqueue task while draining"));
 1204 
 1205         if ((kq->kq_state & KQ_TASKSCHED) != KQ_TASKSCHED) {
 1206                 taskqueue_enqueue(taskqueue_kqueue, &kq->kq_task);
 1207                 kq->kq_state |= KQ_TASKSCHED;
 1208         }
 1209 }
 1210 
 1211 /*
 1212  * Expand the kq to make sure we have storage for fops/ident pair.
 1213  *
 1214  * Return 0 on success (or no work necessary), return errno on failure.
 1215  *
 1216  * Not calling hashinit w/ waitok (proper malloc flag) should be safe.
 1217  * If kqueue_register is called from a non-fd context, there usually/should
 1218  * be no locks held.
 1219  */
 1220 static int
 1221 kqueue_expand(struct kqueue *kq, struct filterops *fops, uintptr_t ident,
 1222         int waitok)
 1223 {
 1224         struct klist *list, *tmp_knhash, *to_free;
 1225         u_long tmp_knhashmask;
 1226         int size;
 1227         int fd;
 1228         int mflag = waitok ? M_WAITOK : M_NOWAIT;
 1229 
 1230         KQ_NOTOWNED(kq);
 1231 
 1232         to_free = NULL;
 1233         if (fops->f_isfd) {
 1234                 fd = ident;
 1235                 if (kq->kq_knlistsize <= fd) {
 1236                         size = kq->kq_knlistsize;
 1237                         while (size <= fd)
 1238                                 size += KQEXTENT;
 1239                         list = malloc(size * sizeof(*list), M_KQUEUE, mflag);
 1240                         if (list == NULL)
 1241                                 return ENOMEM;
 1242                         KQ_LOCK(kq);
 1243                         if (kq->kq_knlistsize > fd) {
 1244                                 to_free = list;
 1245                                 list = NULL;
 1246                         } else {
 1247                                 if (kq->kq_knlist != NULL) {
 1248                                         bcopy(kq->kq_knlist, list,
 1249                                             kq->kq_knlistsize * sizeof(*list));
 1250                                         to_free = kq->kq_knlist;
 1251                                         kq->kq_knlist = NULL;
 1252                                 }
 1253                                 bzero((caddr_t)list +
 1254                                     kq->kq_knlistsize * sizeof(*list),
 1255                                     (size - kq->kq_knlistsize) * sizeof(*list));
 1256                                 kq->kq_knlistsize = size;
 1257                                 kq->kq_knlist = list;
 1258                         }
 1259                         KQ_UNLOCK(kq);
 1260                 }
 1261         } else {
 1262                 if (kq->kq_knhashmask == 0) {
 1263                         tmp_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
 1264                             &tmp_knhashmask);
 1265                         if (tmp_knhash == NULL)
 1266                                 return ENOMEM;
 1267                         KQ_LOCK(kq);
 1268                         if (kq->kq_knhashmask == 0) {
 1269                                 kq->kq_knhash = tmp_knhash;
 1270                                 kq->kq_knhashmask = tmp_knhashmask;
 1271                         } else {
 1272                                 to_free = tmp_knhash;
 1273                         }
 1274                         KQ_UNLOCK(kq);
 1275                 }
 1276         }
 1277         free(to_free, M_KQUEUE);
 1278 
 1279         KQ_NOTOWNED(kq);
 1280         return 0;
 1281 }
 1282 
 1283 static void
 1284 kqueue_task(void *arg, int pending)
 1285 {
 1286         struct kqueue *kq;
 1287         int haskqglobal;
 1288 
 1289         haskqglobal = 0;
 1290         kq = arg;
 1291 
 1292         KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1293         KQ_LOCK(kq);
 1294 
 1295         KNOTE_LOCKED(&kq->kq_sel.si_note, 0);
 1296 
 1297         kq->kq_state &= ~KQ_TASKSCHED;
 1298         if ((kq->kq_state & KQ_TASKDRAIN) == KQ_TASKDRAIN) {
 1299                 wakeup(&kq->kq_state);
 1300         }
 1301         KQ_UNLOCK(kq);
 1302         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1303 }
 1304 
 1305 /*
 1306  * Scan, update kn_data (if not ONESHOT), and copyout triggered events.
 1307  * We treat KN_MARKER knotes as if they are INFLUX.
 1308  */
 1309 static int
 1310 kqueue_scan(struct kqueue *kq, int maxevents, struct kevent_copyops *k_ops,
 1311     const struct timespec *tsp, struct kevent *keva, struct thread *td)
 1312 {
 1313         struct kevent *kevp;
 1314         struct timeval atv, rtv, ttv;
 1315         struct knote *kn, *marker;
 1316         int count, timeout, nkev, error, influx;
 1317         int haskqglobal, touch;
 1318 
 1319         count = maxevents;
 1320         nkev = 0;
 1321         error = 0;
 1322         haskqglobal = 0;
 1323 
 1324         if (maxevents == 0)
 1325                 goto done_nl;
 1326 
 1327         if (tsp != NULL) {
 1328                 TIMESPEC_TO_TIMEVAL(&atv, tsp);
 1329                 if (itimerfix(&atv)) {
 1330                         error = EINVAL;
 1331                         goto done_nl;
 1332                 }
 1333                 if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
 1334                         timeout = -1;
 1335                 else
 1336                         timeout = atv.tv_sec > 24 * 60 * 60 ?
 1337                             24 * 60 * 60 * hz : tvtohz(&atv);
 1338                 getmicrouptime(&rtv);
 1339                 timevaladd(&atv, &rtv);
 1340         } else {
 1341                 atv.tv_sec = 0;
 1342                 atv.tv_usec = 0;
 1343                 timeout = 0;
 1344         }
 1345         marker = knote_alloc(1);
 1346         if (marker == NULL) {
 1347                 error = ENOMEM;
 1348                 goto done_nl;
 1349         }
 1350         marker->kn_status = KN_MARKER;
 1351         KQ_LOCK(kq);
 1352         goto start;
 1353 
 1354 retry:
 1355         if (atv.tv_sec || atv.tv_usec) {
 1356                 getmicrouptime(&rtv);
 1357                 if (timevalcmp(&rtv, &atv, >=))
 1358                         goto done;
 1359                 ttv = atv;
 1360                 timevalsub(&ttv, &rtv);
 1361                 timeout = ttv.tv_sec > 24 * 60 * 60 ?
 1362                         24 * 60 * 60 * hz : tvtohz(&ttv);
 1363         }
 1364 
 1365 start:
 1366         kevp = keva;
 1367         if (kq->kq_count == 0) {
 1368                 if (timeout < 0) {
 1369                         error = EWOULDBLOCK;
 1370                 } else {
 1371                         kq->kq_state |= KQ_SLEEP;
 1372                         error = msleep(kq, &kq->kq_lock, PSOCK | PCATCH,
 1373                             "kqread", timeout);
 1374                 }
 1375                 if (error == 0)
 1376                         goto retry;
 1377                 /* don't restart after signals... */
 1378                 if (error == ERESTART)
 1379                         error = EINTR;
 1380                 else if (error == EWOULDBLOCK)
 1381                         error = 0;
 1382                 goto done;
 1383         }
 1384 
 1385         TAILQ_INSERT_TAIL(&kq->kq_head, marker, kn_tqe);
 1386         influx = 0;
 1387         while (count) {
 1388                 KQ_OWNED(kq);
 1389                 kn = TAILQ_FIRST(&kq->kq_head);
 1390 
 1391                 if ((kn->kn_status == KN_MARKER && kn != marker) ||
 1392                     (kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1393                         if (influx) {
 1394                                 influx = 0;
 1395                                 KQ_FLUX_WAKEUP(kq);
 1396                         }
 1397                         kq->kq_state |= KQ_FLUXWAIT;
 1398                         error = msleep(kq, &kq->kq_lock, PSOCK,
 1399                             "kqflxwt", 0);
 1400                         continue;
 1401                 }
 1402 
 1403                 TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
 1404                 if ((kn->kn_status & KN_DISABLED) == KN_DISABLED) {
 1405                         kn->kn_status &= ~KN_QUEUED;
 1406                         kq->kq_count--;
 1407                         continue;
 1408                 }
 1409                 if (kn == marker) {
 1410                         KQ_FLUX_WAKEUP(kq);
 1411                         if (count == maxevents)
 1412                                 goto retry;
 1413                         goto done;
 1414                 }
 1415                 KASSERT((kn->kn_status & KN_INFLUX) == 0,
 1416                     ("KN_INFLUX set when not suppose to be"));
 1417 
 1418                 if ((kn->kn_flags & EV_ONESHOT) == EV_ONESHOT) {
 1419                         kn->kn_status &= ~KN_QUEUED;
 1420                         kn->kn_status |= KN_INFLUX;
 1421                         kq->kq_count--;
 1422                         KQ_UNLOCK(kq);
 1423                         /*
 1424                          * We don't need to lock the list since we've marked
 1425                          * it _INFLUX.
 1426                          */
 1427                         *kevp = kn->kn_kevent;
 1428                         if (!(kn->kn_status & KN_DETACHED))
 1429                                 kn->kn_fop->f_detach(kn);
 1430                         knote_drop(kn, td);
 1431                         KQ_LOCK(kq);
 1432                         kn = NULL;
 1433                 } else {
 1434                         kn->kn_status |= KN_INFLUX;
 1435                         KQ_UNLOCK(kq);
 1436                         if ((kn->kn_status & KN_KQUEUE) == KN_KQUEUE)
 1437                                 KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1438                         KN_LIST_LOCK(kn);
 1439                         if (kn->kn_fop->f_event(kn, 0) == 0) {
 1440                                 KQ_LOCK(kq);
 1441                                 KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1442                                 kn->kn_status &=
 1443                                     ~(KN_QUEUED | KN_ACTIVE | KN_INFLUX);
 1444                                 kq->kq_count--;
 1445                                 KN_LIST_UNLOCK(kn);
 1446                                 influx = 1;
 1447                                 continue;
 1448                         }
 1449                         touch = (!kn->kn_fop->f_isfd &&
 1450                             kn->kn_fop->f_touch != NULL);
 1451                         if (touch)
 1452                                 kn->kn_fop->f_touch(kn, kevp, EVENT_PROCESS);
 1453                         else
 1454                                 *kevp = kn->kn_kevent;
 1455                         KQ_LOCK(kq);
 1456                         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1457                         if (kn->kn_flags & (EV_CLEAR |  EV_DISPATCH)) {
 1458                                 /* 
 1459                                  * Manually clear knotes who weren't 
 1460                                  * 'touch'ed.
 1461                                  */
 1462                                 if (touch == 0 && kn->kn_flags & EV_CLEAR) {
 1463                                         kn->kn_data = 0;
 1464                                         kn->kn_fflags = 0;
 1465                                 }
 1466                                 if (kn->kn_flags & EV_DISPATCH)
 1467                                         kn->kn_status |= KN_DISABLED;
 1468                                 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
 1469                                 kq->kq_count--;
 1470                         } else
 1471                                 TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
 1472                         
 1473                         kn->kn_status &= ~(KN_INFLUX);
 1474                         KN_LIST_UNLOCK(kn);
 1475                         influx = 1;
 1476                 }
 1477 
 1478                 /* we are returning a copy to the user */
 1479                 kevp++;
 1480                 nkev++;
 1481                 count--;
 1482 
 1483                 if (nkev == KQ_NEVENTS) {
 1484                         influx = 0;
 1485                         KQ_UNLOCK_FLUX(kq);
 1486                         error = k_ops->k_copyout(k_ops->arg, keva, nkev);
 1487                         nkev = 0;
 1488                         kevp = keva;
 1489                         KQ_LOCK(kq);
 1490                         if (error)
 1491                                 break;
 1492                 }
 1493         }
 1494         TAILQ_REMOVE(&kq->kq_head, marker, kn_tqe);
 1495 done:
 1496         KQ_OWNED(kq);
 1497         KQ_UNLOCK_FLUX(kq);
 1498         knote_free(marker);
 1499 done_nl:
 1500         KQ_NOTOWNED(kq);
 1501         if (nkev != 0)
 1502                 error = k_ops->k_copyout(k_ops->arg, keva, nkev);
 1503         td->td_retval[0] = maxevents - count;
 1504         return (error);
 1505 }
 1506 
 1507 /*
 1508  * XXX
 1509  * This could be expanded to call kqueue_scan, if desired.
 1510  */
 1511 /*ARGSUSED*/
 1512 static int
 1513 kqueue_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1514         int flags, struct thread *td)
 1515 {
 1516         return (ENXIO);
 1517 }
 1518 
 1519 /*ARGSUSED*/
 1520 static int
 1521 kqueue_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1522          int flags, struct thread *td)
 1523 {
 1524         return (ENXIO);
 1525 }
 1526 
 1527 /*ARGSUSED*/
 1528 static int
 1529 kqueue_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 1530         struct thread *td)
 1531 {
 1532 
 1533         return (EINVAL);
 1534 }
 1535 
 1536 /*ARGSUSED*/
 1537 static int
 1538 kqueue_ioctl(struct file *fp, u_long cmd, void *data,
 1539         struct ucred *active_cred, struct thread *td)
 1540 {
 1541         /*
 1542          * Enabling sigio causes two major problems:
 1543          * 1) infinite recursion:
 1544          * Synopsys: kevent is being used to track signals and have FIOASYNC
 1545          * set.  On receipt of a signal this will cause a kqueue to recurse
 1546          * into itself over and over.  Sending the sigio causes the kqueue
 1547          * to become ready, which in turn posts sigio again, forever.
 1548          * Solution: this can be solved by setting a flag in the kqueue that
 1549          * we have a SIGIO in progress.
 1550          * 2) locking problems:
 1551          * Synopsys: Kqueue is a leaf subsystem, but adding signalling puts
 1552          * us above the proc and pgrp locks.
 1553          * Solution: Post a signal using an async mechanism, being sure to
 1554          * record a generation count in the delivery so that we do not deliver
 1555          * a signal to the wrong process.
 1556          *
 1557          * Note, these two mechanisms are somewhat mutually exclusive!
 1558          */
 1559 #if 0
 1560         struct kqueue *kq;
 1561 
 1562         kq = fp->f_data;
 1563         switch (cmd) {
 1564         case FIOASYNC:
 1565                 if (*(int *)data) {
 1566                         kq->kq_state |= KQ_ASYNC;
 1567                 } else {
 1568                         kq->kq_state &= ~KQ_ASYNC;
 1569                 }
 1570                 return (0);
 1571 
 1572         case FIOSETOWN:
 1573                 return (fsetown(*(int *)data, &kq->kq_sigio));
 1574 
 1575         case FIOGETOWN:
 1576                 *(int *)data = fgetown(&kq->kq_sigio);
 1577                 return (0);
 1578         }
 1579 #endif
 1580 
 1581         return (ENOTTY);
 1582 }
 1583 
 1584 /*ARGSUSED*/
 1585 static int
 1586 kqueue_poll(struct file *fp, int events, struct ucred *active_cred,
 1587         struct thread *td)
 1588 {
 1589         struct kqueue *kq;
 1590         int revents = 0;
 1591         int error;
 1592 
 1593         if ((error = kqueue_acquire(fp, &kq)))
 1594                 return POLLERR;
 1595 
 1596         KQ_LOCK(kq);
 1597         if (events & (POLLIN | POLLRDNORM)) {
 1598                 if (kq->kq_count) {
 1599                         revents |= events & (POLLIN | POLLRDNORM);
 1600                 } else {
 1601                         selrecord(td, &kq->kq_sel);
 1602                         if (SEL_WAITING(&kq->kq_sel))
 1603                                 kq->kq_state |= KQ_SEL;
 1604                 }
 1605         }
 1606         kqueue_release(kq, 1);
 1607         KQ_UNLOCK(kq);
 1608         return (revents);
 1609 }
 1610 
 1611 /*ARGSUSED*/
 1612 static int
 1613 kqueue_stat(struct file *fp, struct stat *st, struct ucred *active_cred,
 1614         struct thread *td)
 1615 {
 1616 
 1617         bzero((void *)st, sizeof *st);
 1618         /*
 1619          * We no longer return kq_count because the unlocked value is useless.
 1620          * If you spent all this time getting the count, why not spend your
 1621          * syscall better by calling kevent?
 1622          *
 1623          * XXX - This is needed for libc_r.
 1624          */
 1625         st->st_mode = S_IFIFO;
 1626         return (0);
 1627 }
 1628 
 1629 /*ARGSUSED*/
 1630 static int
 1631 kqueue_close(struct file *fp, struct thread *td)
 1632 {
 1633         struct kqueue *kq = fp->f_data;
 1634         struct filedesc *fdp;
 1635         struct knote *kn;
 1636         int i;
 1637         int error;
 1638 
 1639         if ((error = kqueue_acquire(fp, &kq)))
 1640                 return error;
 1641 
 1642         KQ_LOCK(kq);
 1643 
 1644         KASSERT((kq->kq_state & KQ_CLOSING) != KQ_CLOSING,
 1645             ("kqueue already closing"));
 1646         kq->kq_state |= KQ_CLOSING;
 1647         if (kq->kq_refcnt > 1)
 1648                 msleep(&kq->kq_refcnt, &kq->kq_lock, PSOCK, "kqclose", 0);
 1649 
 1650         KASSERT(kq->kq_refcnt == 1, ("other refs are out there!"));
 1651         fdp = kq->kq_fdp;
 1652 
 1653         KASSERT(knlist_empty(&kq->kq_sel.si_note),
 1654             ("kqueue's knlist not empty"));
 1655 
 1656         for (i = 0; i < kq->kq_knlistsize; i++) {
 1657                 while ((kn = SLIST_FIRST(&kq->kq_knlist[i])) != NULL) {
 1658                         if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1659                                 kq->kq_state |= KQ_FLUXWAIT;
 1660                                 msleep(kq, &kq->kq_lock, PSOCK, "kqclo1", 0);
 1661                                 continue;
 1662                         }
 1663                         kn->kn_status |= KN_INFLUX;
 1664                         KQ_UNLOCK(kq);
 1665                         if (!(kn->kn_status & KN_DETACHED))
 1666                                 kn->kn_fop->f_detach(kn);
 1667                         knote_drop(kn, td);
 1668                         KQ_LOCK(kq);
 1669                 }
 1670         }
 1671         if (kq->kq_knhashmask != 0) {
 1672                 for (i = 0; i <= kq->kq_knhashmask; i++) {
 1673                         while ((kn = SLIST_FIRST(&kq->kq_knhash[i])) != NULL) {
 1674                                 if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1675                                         kq->kq_state |= KQ_FLUXWAIT;
 1676                                         msleep(kq, &kq->kq_lock, PSOCK,
 1677                                                "kqclo2", 0);
 1678                                         continue;
 1679                                 }
 1680                                 kn->kn_status |= KN_INFLUX;
 1681                                 KQ_UNLOCK(kq);
 1682                                 if (!(kn->kn_status & KN_DETACHED))
 1683                                         kn->kn_fop->f_detach(kn);
 1684                                 knote_drop(kn, td);
 1685                                 KQ_LOCK(kq);
 1686                         }
 1687                 }
 1688         }
 1689 
 1690         if ((kq->kq_state & KQ_TASKSCHED) == KQ_TASKSCHED) {
 1691                 kq->kq_state |= KQ_TASKDRAIN;
 1692                 msleep(&kq->kq_state, &kq->kq_lock, PSOCK, "kqtqdr", 0);
 1693         }
 1694 
 1695         if ((kq->kq_state & KQ_SEL) == KQ_SEL) {
 1696                 selwakeuppri(&kq->kq_sel, PSOCK);
 1697                 if (!SEL_WAITING(&kq->kq_sel))
 1698                         kq->kq_state &= ~KQ_SEL;
 1699         }
 1700 
 1701         KQ_UNLOCK(kq);
 1702 
 1703         FILEDESC_XLOCK(fdp);
 1704         SLIST_REMOVE(&fdp->fd_kqlist, kq, kqueue, kq_list);
 1705         FILEDESC_XUNLOCK(fdp);
 1706 
 1707         seldrain(&kq->kq_sel);
 1708         knlist_destroy(&kq->kq_sel.si_note);
 1709         mtx_destroy(&kq->kq_lock);
 1710         kq->kq_fdp = NULL;
 1711 
 1712         if (kq->kq_knhash != NULL)
 1713                 free(kq->kq_knhash, M_KQUEUE);
 1714         if (kq->kq_knlist != NULL)
 1715                 free(kq->kq_knlist, M_KQUEUE);
 1716 
 1717         funsetown(&kq->kq_sigio);
 1718         free(kq, M_KQUEUE);
 1719         fp->f_data = NULL;
 1720 
 1721         return (0);
 1722 }
 1723 
 1724 static void
 1725 kqueue_wakeup(struct kqueue *kq)
 1726 {
 1727         KQ_OWNED(kq);
 1728 
 1729         if ((kq->kq_state & KQ_SLEEP) == KQ_SLEEP) {
 1730                 kq->kq_state &= ~KQ_SLEEP;
 1731                 wakeup(kq);
 1732         }
 1733         if ((kq->kq_state & KQ_SEL) == KQ_SEL) {
 1734                 selwakeuppri(&kq->kq_sel, PSOCK);
 1735                 if (!SEL_WAITING(&kq->kq_sel))
 1736                         kq->kq_state &= ~KQ_SEL;
 1737         }
 1738         if (!knlist_empty(&kq->kq_sel.si_note))
 1739                 kqueue_schedtask(kq);
 1740         if ((kq->kq_state & KQ_ASYNC) == KQ_ASYNC) {
 1741                 pgsigio(&kq->kq_sigio, SIGIO, 0);
 1742         }
 1743 }
 1744 
 1745 /*
 1746  * Walk down a list of knotes, activating them if their event has triggered.
 1747  *
 1748  * There is a possibility to optimize in the case of one kq watching another.
 1749  * Instead of scheduling a task to wake it up, you could pass enough state
 1750  * down the chain to make up the parent kqueue.  Make this code functional
 1751  * first.
 1752  */
 1753 void
 1754 knote(struct knlist *list, long hint, int lockflags)
 1755 {
 1756         struct kqueue *kq;
 1757         struct knote *kn;
 1758         int error;
 1759 
 1760         if (list == NULL)
 1761                 return;
 1762 
 1763         KNL_ASSERT_LOCK(list, lockflags & KNF_LISTLOCKED);
 1764 
 1765         if ((lockflags & KNF_LISTLOCKED) == 0)
 1766                 list->kl_lock(list->kl_lockarg); 
 1767 
 1768         /*
 1769          * If we unlock the list lock (and set KN_INFLUX), we can eliminate
 1770          * the kqueue scheduling, but this will introduce four
 1771          * lock/unlock's for each knote to test.  If we do, continue to use
 1772          * SLIST_FOREACH, SLIST_FOREACH_SAFE is not safe in our case, it is
 1773          * only safe if you want to remove the current item, which we are
 1774          * not doing.
 1775          */
 1776         SLIST_FOREACH(kn, &list->kl_list, kn_selnext) {
 1777                 kq = kn->kn_kq;
 1778                 if ((kn->kn_status & KN_INFLUX) != KN_INFLUX) {
 1779                         KQ_LOCK(kq);
 1780                         if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1781                                 KQ_UNLOCK(kq);
 1782                         } else if ((lockflags & KNF_NOKQLOCK) != 0) {
 1783                                 kn->kn_status |= KN_INFLUX;
 1784                                 KQ_UNLOCK(kq);
 1785                                 error = kn->kn_fop->f_event(kn, hint);
 1786                                 KQ_LOCK(kq);
 1787                                 kn->kn_status &= ~KN_INFLUX;
 1788                                 if (error)
 1789                                         KNOTE_ACTIVATE(kn, 1);
 1790                                 KQ_UNLOCK_FLUX(kq);
 1791                         } else {
 1792                                 kn->kn_status |= KN_HASKQLOCK;
 1793                                 if (kn->kn_fop->f_event(kn, hint))
 1794                                         KNOTE_ACTIVATE(kn, 1);
 1795                                 kn->kn_status &= ~KN_HASKQLOCK;
 1796                                 KQ_UNLOCK(kq);
 1797                         }
 1798                 }
 1799                 kq = NULL;
 1800         }
 1801         if ((lockflags & KNF_LISTLOCKED) == 0)
 1802                 list->kl_unlock(list->kl_lockarg); 
 1803 }
 1804 
 1805 /*
 1806  * add a knote to a knlist
 1807  */
 1808 void
 1809 knlist_add(struct knlist *knl, struct knote *kn, int islocked)
 1810 {
 1811         KNL_ASSERT_LOCK(knl, islocked);
 1812         KQ_NOTOWNED(kn->kn_kq);
 1813         KASSERT((kn->kn_status & (KN_INFLUX|KN_DETACHED)) ==
 1814             (KN_INFLUX|KN_DETACHED), ("knote not KN_INFLUX and KN_DETACHED"));
 1815         if (!islocked)
 1816                 knl->kl_lock(knl->kl_lockarg);
 1817         SLIST_INSERT_HEAD(&knl->kl_list, kn, kn_selnext);
 1818         if (!islocked)
 1819                 knl->kl_unlock(knl->kl_lockarg);
 1820         KQ_LOCK(kn->kn_kq);
 1821         kn->kn_knlist = knl;
 1822         kn->kn_status &= ~KN_DETACHED;
 1823         KQ_UNLOCK(kn->kn_kq);
 1824 }
 1825 
 1826 static void
 1827 knlist_remove_kq(struct knlist *knl, struct knote *kn, int knlislocked, int kqislocked)
 1828 {
 1829         KASSERT(!(!!kqislocked && !knlislocked), ("kq locked w/o knl locked"));
 1830         KNL_ASSERT_LOCK(knl, knlislocked);
 1831         mtx_assert(&kn->kn_kq->kq_lock, kqislocked ? MA_OWNED : MA_NOTOWNED);
 1832         if (!kqislocked)
 1833                 KASSERT((kn->kn_status & (KN_INFLUX|KN_DETACHED)) == KN_INFLUX,
 1834     ("knlist_remove called w/o knote being KN_INFLUX or already removed"));
 1835         if (!knlislocked)
 1836                 knl->kl_lock(knl->kl_lockarg);
 1837         SLIST_REMOVE(&knl->kl_list, kn, knote, kn_selnext);
 1838         kn->kn_knlist = NULL;
 1839         if (!knlislocked)
 1840                 knl->kl_unlock(knl->kl_lockarg);
 1841         if (!kqislocked)
 1842                 KQ_LOCK(kn->kn_kq);
 1843         kn->kn_status |= KN_DETACHED;
 1844         if (!kqislocked)
 1845                 KQ_UNLOCK(kn->kn_kq);
 1846 }
 1847 
 1848 /*
 1849  * remove all knotes from a specified klist
 1850  */
 1851 void
 1852 knlist_remove(struct knlist *knl, struct knote *kn, int islocked)
 1853 {
 1854 
 1855         knlist_remove_kq(knl, kn, islocked, 0);
 1856 }
 1857 
 1858 /*
 1859  * remove knote from a specified klist while in f_event handler.
 1860  */
 1861 void
 1862 knlist_remove_inevent(struct knlist *knl, struct knote *kn)
 1863 {
 1864 
 1865         knlist_remove_kq(knl, kn, 1,
 1866             (kn->kn_status & KN_HASKQLOCK) == KN_HASKQLOCK);
 1867 }
 1868 
 1869 int
 1870 knlist_empty(struct knlist *knl)
 1871 {
 1872         KNL_ASSERT_LOCKED(knl);
 1873         return SLIST_EMPTY(&knl->kl_list);
 1874 }
 1875 
 1876 static struct mtx       knlist_lock;
 1877 MTX_SYSINIT(knlist_lock, &knlist_lock, "knlist lock for lockless objects",
 1878         MTX_DEF);
 1879 static void knlist_mtx_lock(void *arg);
 1880 static void knlist_mtx_unlock(void *arg);
 1881 
 1882 static void
 1883 knlist_mtx_lock(void *arg)
 1884 {
 1885         mtx_lock((struct mtx *)arg);
 1886 }
 1887 
 1888 static void
 1889 knlist_mtx_unlock(void *arg)
 1890 {
 1891         mtx_unlock((struct mtx *)arg);
 1892 }
 1893 
 1894 static void
 1895 knlist_mtx_assert_locked(void *arg)
 1896 {
 1897         mtx_assert((struct mtx *)arg, MA_OWNED);
 1898 }
 1899 
 1900 static void
 1901 knlist_mtx_assert_unlocked(void *arg)
 1902 {
 1903         mtx_assert((struct mtx *)arg, MA_NOTOWNED);
 1904 }
 1905 
 1906 void
 1907 knlist_init(struct knlist *knl, void *lock, void (*kl_lock)(void *),
 1908     void (*kl_unlock)(void *),
 1909     void (*kl_assert_locked)(void *), void (*kl_assert_unlocked)(void *))
 1910 {
 1911 
 1912         if (lock == NULL)
 1913                 knl->kl_lockarg = &knlist_lock;
 1914         else
 1915                 knl->kl_lockarg = lock;
 1916 
 1917         if (kl_lock == NULL)
 1918                 knl->kl_lock = knlist_mtx_lock;
 1919         else
 1920                 knl->kl_lock = kl_lock;
 1921         if (kl_unlock == NULL)
 1922                 knl->kl_unlock = knlist_mtx_unlock;
 1923         else
 1924                 knl->kl_unlock = kl_unlock;
 1925         if (kl_assert_locked == NULL)
 1926                 knl->kl_assert_locked = knlist_mtx_assert_locked;
 1927         else
 1928                 knl->kl_assert_locked = kl_assert_locked;
 1929         if (kl_assert_unlocked == NULL)
 1930                 knl->kl_assert_unlocked = knlist_mtx_assert_unlocked;
 1931         else
 1932                 knl->kl_assert_unlocked = kl_assert_unlocked;
 1933 
 1934         SLIST_INIT(&knl->kl_list);
 1935 }
 1936 
 1937 void
 1938 knlist_init_mtx(struct knlist *knl, struct mtx *lock)
 1939 {
 1940 
 1941         knlist_init(knl, lock, NULL, NULL, NULL, NULL);
 1942 }
 1943 
 1944 void
 1945 knlist_destroy(struct knlist *knl)
 1946 {
 1947 
 1948 #ifdef INVARIANTS
 1949         /*
 1950          * if we run across this error, we need to find the offending
 1951          * driver and have it call knlist_clear.
 1952          */
 1953         if (!SLIST_EMPTY(&knl->kl_list))
 1954                 printf("WARNING: destroying knlist w/ knotes on it!\n");
 1955 #endif
 1956 
 1957         knl->kl_lockarg = knl->kl_lock = knl->kl_unlock = NULL;
 1958         SLIST_INIT(&knl->kl_list);
 1959 }
 1960 
 1961 /*
 1962  * Even if we are locked, we may need to drop the lock to allow any influx
 1963  * knotes time to "settle".
 1964  */
 1965 void
 1966 knlist_cleardel(struct knlist *knl, struct thread *td, int islocked, int killkn)
 1967 {
 1968         struct knote *kn, *kn2;
 1969         struct kqueue *kq;
 1970 
 1971         if (islocked)
 1972                 KNL_ASSERT_LOCKED(knl);
 1973         else {
 1974                 KNL_ASSERT_UNLOCKED(knl);
 1975 again:          /* need to reacquire lock since we have dropped it */
 1976                 knl->kl_lock(knl->kl_lockarg);
 1977         }
 1978 
 1979         SLIST_FOREACH_SAFE(kn, &knl->kl_list, kn_selnext, kn2) {
 1980                 kq = kn->kn_kq;
 1981                 KQ_LOCK(kq);
 1982                 if ((kn->kn_status & KN_INFLUX)) {
 1983                         KQ_UNLOCK(kq);
 1984                         continue;
 1985                 }
 1986                 knlist_remove_kq(knl, kn, 1, 1);
 1987                 if (killkn) {
 1988                         kn->kn_status |= KN_INFLUX | KN_DETACHED;
 1989                         KQ_UNLOCK(kq);
 1990                         knote_drop(kn, td);
 1991                 } else {
 1992                         /* Make sure cleared knotes disappear soon */
 1993                         kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 1994                         KQ_UNLOCK(kq);
 1995                 }
 1996                 kq = NULL;
 1997         }
 1998 
 1999         if (!SLIST_EMPTY(&knl->kl_list)) {
 2000                 /* there are still KN_INFLUX remaining */
 2001                 kn = SLIST_FIRST(&knl->kl_list);
 2002                 kq = kn->kn_kq;
 2003                 KQ_LOCK(kq);
 2004                 KASSERT(kn->kn_status & KN_INFLUX,
 2005                     ("knote removed w/o list lock"));
 2006                 knl->kl_unlock(knl->kl_lockarg);
 2007                 kq->kq_state |= KQ_FLUXWAIT;
 2008                 msleep(kq, &kq->kq_lock, PSOCK | PDROP, "kqkclr", 0);
 2009                 kq = NULL;
 2010                 goto again;
 2011         }
 2012 
 2013         if (islocked)
 2014                 KNL_ASSERT_LOCKED(knl);
 2015         else {
 2016                 knl->kl_unlock(knl->kl_lockarg);
 2017                 KNL_ASSERT_UNLOCKED(knl);
 2018         }
 2019 }
 2020 
 2021 /*
 2022  * Remove all knotes referencing a specified fd must be called with FILEDESC
 2023  * lock.  This prevents a race where a new fd comes along and occupies the
 2024  * entry and we attach a knote to the fd.
 2025  */
 2026 void
 2027 knote_fdclose(struct thread *td, int fd)
 2028 {
 2029         struct filedesc *fdp = td->td_proc->p_fd;
 2030         struct kqueue *kq;
 2031         struct knote *kn;
 2032         int influx;
 2033 
 2034         FILEDESC_XLOCK_ASSERT(fdp);
 2035 
 2036         /*
 2037          * We shouldn't have to worry about new kevents appearing on fd
 2038          * since filedesc is locked.
 2039          */
 2040         SLIST_FOREACH(kq, &fdp->fd_kqlist, kq_list) {
 2041                 KQ_LOCK(kq);
 2042 
 2043 again:
 2044                 influx = 0;
 2045                 while (kq->kq_knlistsize > fd &&
 2046                     (kn = SLIST_FIRST(&kq->kq_knlist[fd])) != NULL) {
 2047                         if (kn->kn_status & KN_INFLUX) {
 2048                                 /* someone else might be waiting on our knote */
 2049                                 if (influx)
 2050                                         wakeup(kq);
 2051                                 kq->kq_state |= KQ_FLUXWAIT;
 2052                                 msleep(kq, &kq->kq_lock, PSOCK, "kqflxwt", 0);
 2053                                 goto again;
 2054                         }
 2055                         kn->kn_status |= KN_INFLUX;
 2056                         KQ_UNLOCK(kq);
 2057                         if (!(kn->kn_status & KN_DETACHED))
 2058                                 kn->kn_fop->f_detach(kn);
 2059                         knote_drop(kn, td);
 2060                         influx = 1;
 2061                         KQ_LOCK(kq);
 2062                 }
 2063                 KQ_UNLOCK_FLUX(kq);
 2064         }
 2065 }
 2066 
 2067 static int
 2068 knote_attach(struct knote *kn, struct kqueue *kq)
 2069 {
 2070         struct klist *list;
 2071 
 2072         KASSERT(kn->kn_status & KN_INFLUX, ("knote not marked INFLUX"));
 2073         KQ_OWNED(kq);
 2074 
 2075         if (kn->kn_fop->f_isfd) {
 2076                 if (kn->kn_id >= kq->kq_knlistsize)
 2077                         return ENOMEM;
 2078                 list = &kq->kq_knlist[kn->kn_id];
 2079         } else {
 2080                 if (kq->kq_knhash == NULL)
 2081                         return ENOMEM;
 2082                 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
 2083         }
 2084 
 2085         SLIST_INSERT_HEAD(list, kn, kn_link);
 2086 
 2087         return 0;
 2088 }
 2089 
 2090 /*
 2091  * knote must already have been detached using the f_detach method.
 2092  * no lock need to be held, it is assumed that the KN_INFLUX flag is set
 2093  * to prevent other removal.
 2094  */
 2095 static void
 2096 knote_drop(struct knote *kn, struct thread *td)
 2097 {
 2098         struct kqueue *kq;
 2099         struct klist *list;
 2100 
 2101         kq = kn->kn_kq;
 2102 
 2103         KQ_NOTOWNED(kq);
 2104         KASSERT((kn->kn_status & KN_INFLUX) == KN_INFLUX,
 2105             ("knote_drop called without KN_INFLUX set in kn_status"));
 2106 
 2107         KQ_LOCK(kq);
 2108         if (kn->kn_fop->f_isfd)
 2109                 list = &kq->kq_knlist[kn->kn_id];
 2110         else
 2111                 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
 2112 
 2113         if (!SLIST_EMPTY(list))
 2114                 SLIST_REMOVE(list, kn, knote, kn_link);
 2115         if (kn->kn_status & KN_QUEUED)
 2116                 knote_dequeue(kn);
 2117         KQ_UNLOCK_FLUX(kq);
 2118 
 2119         if (kn->kn_fop->f_isfd) {
 2120                 fdrop(kn->kn_fp, td);
 2121                 kn->kn_fp = NULL;
 2122         }
 2123         kqueue_fo_release(kn->kn_kevent.filter);
 2124         kn->kn_fop = NULL;
 2125         knote_free(kn);
 2126 }
 2127 
 2128 static void
 2129 knote_enqueue(struct knote *kn)
 2130 {
 2131         struct kqueue *kq = kn->kn_kq;
 2132 
 2133         KQ_OWNED(kn->kn_kq);
 2134         KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
 2135 
 2136         TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
 2137         kn->kn_status |= KN_QUEUED;
 2138         kq->kq_count++;
 2139         kqueue_wakeup(kq);
 2140 }
 2141 
 2142 static void
 2143 knote_dequeue(struct knote *kn)
 2144 {
 2145         struct kqueue *kq = kn->kn_kq;
 2146 
 2147         KQ_OWNED(kn->kn_kq);
 2148         KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
 2149 
 2150         TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
 2151         kn->kn_status &= ~KN_QUEUED;
 2152         kq->kq_count--;
 2153 }
 2154 
 2155 static void
 2156 knote_init(void)
 2157 {
 2158 
 2159         knote_zone = uma_zcreate("KNOTE", sizeof(struct knote), NULL, NULL,
 2160             NULL, NULL, UMA_ALIGN_PTR, 0);
 2161 }
 2162 SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL);
 2163 
 2164 static struct knote *
 2165 knote_alloc(int waitok)
 2166 {
 2167         return ((struct knote *)uma_zalloc(knote_zone,
 2168             (waitok ? M_WAITOK : M_NOWAIT)|M_ZERO));
 2169 }
 2170 
 2171 static void
 2172 knote_free(struct knote *kn)
 2173 {
 2174         if (kn != NULL)
 2175                 uma_zfree(knote_zone, kn);
 2176 }
 2177 
 2178 /*
 2179  * Register the kev w/ the kq specified by fd.
 2180  */
 2181 int 
 2182 kqfd_register(int fd, struct kevent *kev, struct thread *td, int waitok)
 2183 {
 2184         struct kqueue *kq;
 2185         struct file *fp;
 2186         int error;
 2187 
 2188         if ((error = fget(td, fd, CAP_POST_EVENT, &fp)) != 0)
 2189                 return (error);
 2190         if ((error = kqueue_acquire(fp, &kq)) != 0)
 2191                 goto noacquire;
 2192 
 2193         error = kqueue_register(kq, kev, td, waitok);
 2194 
 2195         kqueue_release(kq, 0);
 2196 
 2197 noacquire:
 2198         fdrop(fp, td);
 2199 
 2200         return error;
 2201 }

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