The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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("$FreeBSD$");
   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/limits.h>
   49 #include <sys/selinfo.h>
   50 #include <sys/queue.h>
   51 #include <sys/event.h>
   52 #include <sys/eventvar.h>
   53 #include <sys/poll.h>
   54 #include <sys/protosw.h>
   55 #include <sys/sigio.h>
   56 #include <sys/signalvar.h>
   57 #include <sys/socket.h>
   58 #include <sys/socketvar.h>
   59 #include <sys/stat.h>
   60 #include <sys/sysctl.h>
   61 #include <sys/sysproto.h>
   62 #include <sys/syscallsubr.h>
   63 #include <sys/taskqueue.h>
   64 #include <sys/uio.h>
   65 #ifdef KTRACE
   66 #include <sys/ktrace.h>
   67 #endif
   68 
   69 #include <vm/uma.h>
   70 
   71 static MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system");
   72 
   73 /*
   74  * This lock is used if multiple kq locks are required.  This possibly
   75  * should be made into a per proc lock.
   76  */
   77 static struct mtx       kq_global;
   78 MTX_SYSINIT(kq_global, &kq_global, "kqueue order", MTX_DEF);
   79 #define KQ_GLOBAL_LOCK(lck, haslck)     do {    \
   80         if (!haslck)                            \
   81                 mtx_lock(lck);                  \
   82         haslck = 1;                             \
   83 } while (0)
   84 #define KQ_GLOBAL_UNLOCK(lck, haslck)   do {    \
   85         if (haslck)                             \
   86                 mtx_unlock(lck);                        \
   87         haslck = 0;                             \
   88 } while (0)
   89 
   90 TASKQUEUE_DEFINE_THREAD(kqueue);
   91 
   92 static int      kevent_copyout(void *arg, struct kevent *kevp, int count);
   93 static int      kevent_copyin(void *arg, struct kevent *kevp, int count);
   94 static int      kqueue_register(struct kqueue *kq, struct kevent *kev,
   95                     struct thread *td, int waitok);
   96 static int      kqueue_acquire(struct file *fp, struct kqueue **kqp);
   97 static void     kqueue_release(struct kqueue *kq, int locked);
   98 static int      kqueue_expand(struct kqueue *kq, struct filterops *fops,
   99                     uintptr_t ident, int waitok);
  100 static void     kqueue_task(void *arg, int pending);
  101 static int      kqueue_scan(struct kqueue *kq, int maxevents,
  102                     struct kevent_copyops *k_ops,
  103                     const struct timespec *timeout,
  104                     struct kevent *keva, struct thread *td);
  105 static void     kqueue_wakeup(struct kqueue *kq);
  106 static struct filterops *kqueue_fo_find(int filt);
  107 static void     kqueue_fo_release(int filt);
  108 
  109 static fo_rdwr_t        kqueue_read;
  110 static fo_rdwr_t        kqueue_write;
  111 static fo_truncate_t    kqueue_truncate;
  112 static fo_ioctl_t       kqueue_ioctl;
  113 static fo_poll_t        kqueue_poll;
  114 static fo_kqfilter_t    kqueue_kqfilter;
  115 static fo_stat_t        kqueue_stat;
  116 static fo_close_t       kqueue_close;
  117 
  118 static struct fileops kqueueops = {
  119         .fo_read = kqueue_read,
  120         .fo_write = kqueue_write,
  121         .fo_truncate = kqueue_truncate,
  122         .fo_ioctl = kqueue_ioctl,
  123         .fo_poll = kqueue_poll,
  124         .fo_kqfilter = kqueue_kqfilter,
  125         .fo_stat = kqueue_stat,
  126         .fo_close = kqueue_close,
  127         .fo_chmod = invfo_chmod,
  128         .fo_chown = invfo_chown,
  129 };
  130 
  131 static int      knote_attach(struct knote *kn, struct kqueue *kq);
  132 static void     knote_drop(struct knote *kn, struct thread *td);
  133 static void     knote_enqueue(struct knote *kn);
  134 static void     knote_dequeue(struct knote *kn);
  135 static void     knote_init(void);
  136 static struct   knote *knote_alloc(int waitok);
  137 static void     knote_free(struct knote *kn);
  138 
  139 static void     filt_kqdetach(struct knote *kn);
  140 static int      filt_kqueue(struct knote *kn, long hint);
  141 static int      filt_procattach(struct knote *kn);
  142 static void     filt_procdetach(struct knote *kn);
  143 static int      filt_proc(struct knote *kn, long hint);
  144 static int      filt_fileattach(struct knote *kn);
  145 static void     filt_timerexpire(void *knx);
  146 static int      filt_timerattach(struct knote *kn);
  147 static void     filt_timerdetach(struct knote *kn);
  148 static int      filt_timer(struct knote *kn, long hint);
  149 static int      filt_userattach(struct knote *kn);
  150 static void     filt_userdetach(struct knote *kn);
  151 static int      filt_user(struct knote *kn, long hint);
  152 static void     filt_usertouch(struct knote *kn, struct kevent *kev,
  153                     u_long type);
  154 
  155 static struct filterops file_filtops = {
  156         .f_isfd = 1,
  157         .f_attach = filt_fileattach,
  158 };
  159 static struct filterops kqread_filtops = {
  160         .f_isfd = 1,
  161         .f_detach = filt_kqdetach,
  162         .f_event = filt_kqueue,
  163 };
  164 /* XXX - move to kern_proc.c?  */
  165 static struct filterops proc_filtops = {
  166         .f_isfd = 0,
  167         .f_attach = filt_procattach,
  168         .f_detach = filt_procdetach,
  169         .f_event = filt_proc,
  170 };
  171 static struct filterops timer_filtops = {
  172         .f_isfd = 0,
  173         .f_attach = filt_timerattach,
  174         .f_detach = filt_timerdetach,
  175         .f_event = filt_timer,
  176 };
  177 static struct filterops user_filtops = {
  178         .f_attach = filt_userattach,
  179         .f_detach = filt_userdetach,
  180         .f_event = filt_user,
  181         .f_touch = filt_usertouch,
  182 };
  183 
  184 static uma_zone_t       knote_zone;
  185 static int              kq_ncallouts = 0;
  186 static int              kq_calloutmax = (4 * 1024);
  187 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW,
  188     &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue");
  189 
  190 /* XXX - ensure not KN_INFLUX?? */
  191 #define KNOTE_ACTIVATE(kn, islock) do {                                 \
  192         if ((islock))                                                   \
  193                 mtx_assert(&(kn)->kn_kq->kq_lock, MA_OWNED);            \
  194         else                                                            \
  195                 KQ_LOCK((kn)->kn_kq);                                   \
  196         (kn)->kn_status |= KN_ACTIVE;                                   \
  197         if (((kn)->kn_status & (KN_QUEUED | KN_DISABLED)) == 0)         \
  198                 knote_enqueue((kn));                                    \
  199         if (!(islock))                                                  \
  200                 KQ_UNLOCK((kn)->kn_kq);                                 \
  201 } while(0)
  202 #define KQ_LOCK(kq) do {                                                \
  203         mtx_lock(&(kq)->kq_lock);                                       \
  204 } while (0)
  205 #define KQ_FLUX_WAKEUP(kq) do {                                         \
  206         if (((kq)->kq_state & KQ_FLUXWAIT) == KQ_FLUXWAIT) {            \
  207                 (kq)->kq_state &= ~KQ_FLUXWAIT;                         \
  208                 wakeup((kq));                                           \
  209         }                                                               \
  210 } while (0)
  211 #define KQ_UNLOCK_FLUX(kq) do {                                         \
  212         KQ_FLUX_WAKEUP(kq);                                             \
  213         mtx_unlock(&(kq)->kq_lock);                                     \
  214 } while (0)
  215 #define KQ_UNLOCK(kq) do {                                              \
  216         mtx_unlock(&(kq)->kq_lock);                                     \
  217 } while (0)
  218 #define KQ_OWNED(kq) do {                                               \
  219         mtx_assert(&(kq)->kq_lock, MA_OWNED);                           \
  220 } while (0)
  221 #define KQ_NOTOWNED(kq) do {                                            \
  222         mtx_assert(&(kq)->kq_lock, MA_NOTOWNED);                        \
  223 } while (0)
  224 #define KN_LIST_LOCK(kn) do {                                           \
  225         if (kn->kn_knlist != NULL)                                      \
  226                 kn->kn_knlist->kl_lock(kn->kn_knlist->kl_lockarg);      \
  227 } while (0)
  228 #define KN_LIST_UNLOCK(kn) do {                                         \
  229         if (kn->kn_knlist != NULL)                                      \
  230                 kn->kn_knlist->kl_unlock(kn->kn_knlist->kl_lockarg);    \
  231 } while (0)
  232 #define KNL_ASSERT_LOCK(knl, islocked) do {                             \
  233         if (islocked)                                                   \
  234                 KNL_ASSERT_LOCKED(knl);                         \
  235         else                                                            \
  236                 KNL_ASSERT_UNLOCKED(knl);                               \
  237 } while (0)
  238 #ifdef INVARIANTS
  239 #define KNL_ASSERT_LOCKED(knl) do {                                     \
  240         knl->kl_assert_locked((knl)->kl_lockarg);                       \
  241 } while (0)
  242 #define KNL_ASSERT_UNLOCKED(knl) do {                                   \
  243         knl->kl_assert_unlocked((knl)->kl_lockarg);                     \
  244 } while (0)
  245 #else /* !INVARIANTS */
  246 #define KNL_ASSERT_LOCKED(knl) do {} while(0)
  247 #define KNL_ASSERT_UNLOCKED(knl) do {} while (0)
  248 #endif /* INVARIANTS */
  249 
  250 #define KN_HASHSIZE             64              /* XXX should be tunable */
  251 #define KN_HASH(val, mask)      (((val) ^ (val >> 8)) & (mask))
  252 
  253 static int
  254 filt_nullattach(struct knote *kn)
  255 {
  256 
  257         return (ENXIO);
  258 };
  259 
  260 struct filterops null_filtops = {
  261         .f_isfd = 0,
  262         .f_attach = filt_nullattach,
  263 };
  264 
  265 /* XXX - make SYSINIT to add these, and move into respective modules. */
  266 extern struct filterops sig_filtops;
  267 extern struct filterops fs_filtops;
  268 
  269 /*
  270  * Table for for all system-defined filters.
  271  */
  272 static struct mtx       filterops_lock;
  273 MTX_SYSINIT(kqueue_filterops, &filterops_lock, "protect sysfilt_ops",
  274         MTX_DEF);
  275 static struct {
  276         struct filterops *for_fop;
  277         int for_refcnt;
  278 } sysfilt_ops[EVFILT_SYSCOUNT] = {
  279         { &file_filtops },                      /* EVFILT_READ */
  280         { &file_filtops },                      /* EVFILT_WRITE */
  281         { &null_filtops },                      /* EVFILT_AIO */
  282         { &file_filtops },                      /* EVFILT_VNODE */
  283         { &proc_filtops },                      /* EVFILT_PROC */
  284         { &sig_filtops },                       /* EVFILT_SIGNAL */
  285         { &timer_filtops },                     /* EVFILT_TIMER */
  286         { &null_filtops },                      /* former EVFILT_NETDEV */
  287         { &fs_filtops },                        /* EVFILT_FS */
  288         { &null_filtops },                      /* EVFILT_LIO */
  289         { &user_filtops },                      /* EVFILT_USER */
  290 };
  291 
  292 /*
  293  * Simple redirection for all cdevsw style objects to call their fo_kqfilter
  294  * method.
  295  */
  296 static int
  297 filt_fileattach(struct knote *kn)
  298 {
  299 
  300         return (fo_kqfilter(kn->kn_fp, kn));
  301 }
  302 
  303 /*ARGSUSED*/
  304 static int
  305 kqueue_kqfilter(struct file *fp, struct knote *kn)
  306 {
  307         struct kqueue *kq = kn->kn_fp->f_data;
  308 
  309         if (kn->kn_filter != EVFILT_READ)
  310                 return (EINVAL);
  311 
  312         kn->kn_status |= KN_KQUEUE;
  313         kn->kn_fop = &kqread_filtops;
  314         knlist_add(&kq->kq_sel.si_note, kn, 0);
  315 
  316         return (0);
  317 }
  318 
  319 static void
  320 filt_kqdetach(struct knote *kn)
  321 {
  322         struct kqueue *kq = kn->kn_fp->f_data;
  323 
  324         knlist_remove(&kq->kq_sel.si_note, kn, 0);
  325 }
  326 
  327 /*ARGSUSED*/
  328 static int
  329 filt_kqueue(struct knote *kn, long hint)
  330 {
  331         struct kqueue *kq = kn->kn_fp->f_data;
  332 
  333         kn->kn_data = kq->kq_count;
  334         return (kn->kn_data > 0);
  335 }
  336 
  337 /* XXX - move to kern_proc.c?  */
  338 static int
  339 filt_procattach(struct knote *kn)
  340 {
  341         struct proc *p;
  342         int immediate;
  343         int error;
  344 
  345         immediate = 0;
  346         p = pfind(kn->kn_id);
  347         if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) {
  348                 p = zpfind(kn->kn_id);
  349                 immediate = 1;
  350         } else if (p != NULL && (p->p_flag & P_WEXIT)) {
  351                 immediate = 1;
  352         }
  353 
  354         if (p == NULL)
  355                 return (ESRCH);
  356         if ((error = p_cansee(curthread, p))) {
  357                 PROC_UNLOCK(p);
  358                 return (error);
  359         }
  360 
  361         kn->kn_ptr.p_proc = p;
  362         kn->kn_flags |= EV_CLEAR;               /* automatically set */
  363 
  364         /*
  365          * internal flag indicating registration done by kernel
  366          */
  367         if (kn->kn_flags & EV_FLAG1) {
  368                 kn->kn_data = kn->kn_sdata;             /* ppid */
  369                 kn->kn_fflags = NOTE_CHILD;
  370                 kn->kn_flags &= ~EV_FLAG1;
  371         }
  372 
  373         if (immediate == 0)
  374                 knlist_add(&p->p_klist, kn, 1);
  375 
  376         /*
  377          * Immediately activate any exit notes if the target process is a
  378          * zombie.  This is necessary to handle the case where the target
  379          * process, e.g. a child, dies before the kevent is registered.
  380          */
  381         if (immediate && filt_proc(kn, NOTE_EXIT))
  382                 KNOTE_ACTIVATE(kn, 0);
  383 
  384         PROC_UNLOCK(p);
  385 
  386         return (0);
  387 }
  388 
  389 /*
  390  * The knote may be attached to a different process, which may exit,
  391  * leaving nothing for the knote to be attached to.  So when the process
  392  * exits, the knote is marked as DETACHED and also flagged as ONESHOT so
  393  * it will be deleted when read out.  However, as part of the knote deletion,
  394  * this routine is called, so a check is needed to avoid actually performing
  395  * a detach, because the original process does not exist any more.
  396  */
  397 /* XXX - move to kern_proc.c?  */
  398 static void
  399 filt_procdetach(struct knote *kn)
  400 {
  401         struct proc *p;
  402 
  403         p = kn->kn_ptr.p_proc;
  404         knlist_remove(&p->p_klist, kn, 0);
  405         kn->kn_ptr.p_proc = NULL;
  406 }
  407 
  408 /* XXX - move to kern_proc.c?  */
  409 static int
  410 filt_proc(struct knote *kn, long hint)
  411 {
  412         struct proc *p = kn->kn_ptr.p_proc;
  413         u_int event;
  414 
  415         /*
  416          * mask off extra data
  417          */
  418         event = (u_int)hint & NOTE_PCTRLMASK;
  419 
  420         /*
  421          * if the user is interested in this event, record it.
  422          */
  423         if (kn->kn_sfflags & event)
  424                 kn->kn_fflags |= event;
  425 
  426         /*
  427          * process is gone, so flag the event as finished.
  428          */
  429         if (event == NOTE_EXIT) {
  430                 if (!(kn->kn_status & KN_DETACHED))
  431                         knlist_remove_inevent(&p->p_klist, kn);
  432                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
  433                 kn->kn_ptr.p_proc = NULL;
  434                 if (kn->kn_fflags & NOTE_EXIT)
  435                         kn->kn_data = p->p_xstat;
  436                 if (kn->kn_fflags == 0)
  437                         kn->kn_flags |= EV_DROP;
  438                 return (1);
  439         }
  440 
  441         return (kn->kn_fflags != 0);
  442 }
  443 
  444 /*
  445  * Called when the process forked. It mostly does the same as the
  446  * knote(), activating all knotes registered to be activated when the
  447  * process forked. Additionally, for each knote attached to the
  448  * parent, check whether user wants to track the new process. If so
  449  * attach a new knote to it, and immediately report an event with the
  450  * child's pid.
  451  */
  452 void
  453 knote_fork(struct knlist *list, int pid)
  454 {
  455         struct kqueue *kq;
  456         struct knote *kn;
  457         struct kevent kev;
  458         int error;
  459 
  460         if (list == NULL)
  461                 return;
  462         list->kl_lock(list->kl_lockarg);
  463 
  464         SLIST_FOREACH(kn, &list->kl_list, kn_selnext) {
  465                 if ((kn->kn_status & KN_INFLUX) == KN_INFLUX)
  466                         continue;
  467                 kq = kn->kn_kq;
  468                 KQ_LOCK(kq);
  469                 if ((kn->kn_status & (KN_INFLUX | KN_SCAN)) == KN_INFLUX) {
  470                         KQ_UNLOCK(kq);
  471                         continue;
  472                 }
  473 
  474                 /*
  475                  * The same as knote(), activate the event.
  476                  */
  477                 if ((kn->kn_sfflags & NOTE_TRACK) == 0) {
  478                         kn->kn_status |= KN_HASKQLOCK;
  479                         if (kn->kn_fop->f_event(kn, NOTE_FORK))
  480                                 KNOTE_ACTIVATE(kn, 1);
  481                         kn->kn_status &= ~KN_HASKQLOCK;
  482                         KQ_UNLOCK(kq);
  483                         continue;
  484                 }
  485 
  486                 /*
  487                  * The NOTE_TRACK case. In addition to the activation
  488                  * of the event, we need to register new event to
  489                  * track the child. Drop the locks in preparation for
  490                  * the call to kqueue_register().
  491                  */
  492                 kn->kn_status |= KN_INFLUX;
  493                 KQ_UNLOCK(kq);
  494                 list->kl_unlock(list->kl_lockarg);
  495 
  496                 /*
  497                  * Activate existing knote and register a knote with
  498                  * new process.
  499                  */
  500                 kev.ident = pid;
  501                 kev.filter = kn->kn_filter;
  502                 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1;
  503                 kev.fflags = kn->kn_sfflags;
  504                 kev.data = kn->kn_id;           /* parent */
  505                 kev.udata = kn->kn_kevent.udata;/* preserve udata */
  506                 error = kqueue_register(kq, &kev, NULL, 0);
  507                 if (error)
  508                         kn->kn_fflags |= NOTE_TRACKERR;
  509                 if (kn->kn_fop->f_event(kn, NOTE_FORK))
  510                         KNOTE_ACTIVATE(kn, 0);
  511                 KQ_LOCK(kq);
  512                 kn->kn_status &= ~KN_INFLUX;
  513                 KQ_UNLOCK_FLUX(kq);
  514                 list->kl_lock(list->kl_lockarg);
  515         }
  516         list->kl_unlock(list->kl_lockarg);
  517 }
  518 
  519 /*
  520  * XXX: EVFILT_TIMER should perhaps live in kern_time.c beside the
  521  * interval timer support code.
  522  */
  523 static int
  524 timertoticks(intptr_t data)
  525 {
  526         struct timeval tv;
  527         int tticks;
  528 
  529         tv.tv_sec = data / 1000;
  530         tv.tv_usec = (data % 1000) * 1000;
  531         tticks = tvtohz(&tv);
  532 
  533         return tticks;
  534 }
  535 
  536 static void
  537 filt_timerexpire(void *knx)
  538 {
  539         struct knote *kn = knx;
  540         struct callout *calloutp;
  541 
  542         kn->kn_data++;
  543         KNOTE_ACTIVATE(kn, 0);  /* XXX - handle locking */
  544 
  545         /*
  546          * timertoticks() uses tvtohz() which always adds 1 to allow
  547          * for the time until the next clock interrupt being strictly
  548          * less than 1 clock tick.  We don't want that here since we
  549          * want to appear to be in sync with the clock interrupt even
  550          * when we're delayed.
  551          */
  552         if ((kn->kn_flags & EV_ONESHOT) != EV_ONESHOT) {
  553                 calloutp = (struct callout *)kn->kn_hook;
  554                 callout_reset_curcpu(calloutp, timertoticks(kn->kn_sdata) - 1,
  555                     filt_timerexpire, kn);
  556         }
  557 }
  558 
  559 /*
  560  * data contains amount of time to sleep, in milliseconds
  561  */
  562 static int
  563 filt_timerattach(struct knote *kn)
  564 {
  565         struct callout *calloutp;
  566 
  567         atomic_add_int(&kq_ncallouts, 1);
  568 
  569         if (kq_ncallouts >= kq_calloutmax) {
  570                 atomic_add_int(&kq_ncallouts, -1);
  571                 return (ENOMEM);
  572         }
  573 
  574         kn->kn_flags |= EV_CLEAR;               /* automatically set */
  575         kn->kn_status &= ~KN_DETACHED;          /* knlist_add usually sets it */
  576         calloutp = malloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
  577         callout_init(calloutp, CALLOUT_MPSAFE);
  578         kn->kn_hook = calloutp;
  579         callout_reset_curcpu(calloutp, timertoticks(kn->kn_sdata),
  580             filt_timerexpire, kn);
  581 
  582         return (0);
  583 }
  584 
  585 static void
  586 filt_timerdetach(struct knote *kn)
  587 {
  588         struct callout *calloutp;
  589 
  590         calloutp = (struct callout *)kn->kn_hook;
  591         callout_drain(calloutp);
  592         free(calloutp, M_KQUEUE);
  593         atomic_add_int(&kq_ncallouts, -1);
  594         kn->kn_status |= KN_DETACHED;   /* knlist_remove usually clears it */
  595 }
  596 
  597 static int
  598 filt_timer(struct knote *kn, long hint)
  599 {
  600 
  601         return (kn->kn_data != 0);
  602 }
  603 
  604 static int
  605 filt_userattach(struct knote *kn)
  606 {
  607 
  608         /* 
  609          * EVFILT_USER knotes are not attached to anything in the kernel.
  610          */ 
  611         kn->kn_hook = NULL;
  612         if (kn->kn_fflags & NOTE_TRIGGER)
  613                 kn->kn_hookid = 1;
  614         else
  615                 kn->kn_hookid = 0;
  616         return (0);
  617 }
  618 
  619 static void
  620 filt_userdetach(__unused struct knote *kn)
  621 {
  622 
  623         /*
  624          * EVFILT_USER knotes are not attached to anything in the kernel.
  625          */
  626 }
  627 
  628 static int
  629 filt_user(struct knote *kn, __unused long hint)
  630 {
  631 
  632         return (kn->kn_hookid);
  633 }
  634 
  635 static void
  636 filt_usertouch(struct knote *kn, struct kevent *kev, u_long type)
  637 {
  638         u_int ffctrl;
  639 
  640         switch (type) {
  641         case EVENT_REGISTER:
  642                 if (kev->fflags & NOTE_TRIGGER)
  643                         kn->kn_hookid = 1;
  644 
  645                 ffctrl = kev->fflags & NOTE_FFCTRLMASK;
  646                 kev->fflags &= NOTE_FFLAGSMASK;
  647                 switch (ffctrl) {
  648                 case NOTE_FFNOP:
  649                         break;
  650 
  651                 case NOTE_FFAND:
  652                         kn->kn_sfflags &= kev->fflags;
  653                         break;
  654 
  655                 case NOTE_FFOR:
  656                         kn->kn_sfflags |= kev->fflags;
  657                         break;
  658 
  659                 case NOTE_FFCOPY:
  660                         kn->kn_sfflags = kev->fflags;
  661                         break;
  662 
  663                 default:
  664                         /* XXX Return error? */
  665                         break;
  666                 }
  667                 kn->kn_sdata = kev->data;
  668                 if (kev->flags & EV_CLEAR) {
  669                         kn->kn_hookid = 0;
  670                         kn->kn_data = 0;
  671                         kn->kn_fflags = 0;
  672                 }
  673                 break;
  674 
  675         case EVENT_PROCESS:
  676                 *kev = kn->kn_kevent;
  677                 kev->fflags = kn->kn_sfflags;
  678                 kev->data = kn->kn_sdata;
  679                 if (kn->kn_flags & EV_CLEAR) {
  680                         kn->kn_hookid = 0;
  681                         kn->kn_data = 0;
  682                         kn->kn_fflags = 0;
  683                 }
  684                 break;
  685 
  686         default:
  687                 panic("filt_usertouch() - invalid type (%ld)", type);
  688                 break;
  689         }
  690 }
  691 
  692 int
  693 sys_kqueue(struct thread *td, struct kqueue_args *uap)
  694 {
  695         struct filedesc *fdp;
  696         struct kqueue *kq;
  697         struct file *fp;
  698         int fd, error;
  699 
  700         fdp = td->td_proc->p_fd;
  701         error = falloc(td, &fp, &fd, 0);
  702         if (error)
  703                 goto done2;
  704 
  705         /* An extra reference on `nfp' has been held for us by falloc(). */
  706         kq = malloc(sizeof *kq, M_KQUEUE, M_WAITOK | M_ZERO);
  707         mtx_init(&kq->kq_lock, "kqueue", NULL, MTX_DEF|MTX_DUPOK);
  708         TAILQ_INIT(&kq->kq_head);
  709         kq->kq_fdp = fdp;
  710         knlist_init_mtx(&kq->kq_sel.si_note, &kq->kq_lock);
  711         TASK_INIT(&kq->kq_task, 0, kqueue_task, kq);
  712 
  713         FILEDESC_XLOCK(fdp);
  714         TAILQ_INSERT_HEAD(&fdp->fd_kqlist, kq, kq_list);
  715         FILEDESC_XUNLOCK(fdp);
  716 
  717         finit(fp, FREAD | FWRITE, DTYPE_KQUEUE, kq, &kqueueops);
  718         fdrop(fp, td);
  719 
  720         td->td_retval[0] = fd;
  721 done2:
  722         return (error);
  723 }
  724 
  725 #ifndef _SYS_SYSPROTO_H_
  726 struct kevent_args {
  727         int     fd;
  728         const struct kevent *changelist;
  729         int     nchanges;
  730         struct  kevent *eventlist;
  731         int     nevents;
  732         const struct timespec *timeout;
  733 };
  734 #endif
  735 int
  736 sys_kevent(struct thread *td, struct kevent_args *uap)
  737 {
  738         struct timespec ts, *tsp;
  739         struct kevent_copyops k_ops = { uap,
  740                                         kevent_copyout,
  741                                         kevent_copyin};
  742         int error;
  743 #ifdef KTRACE
  744         struct uio ktruio;
  745         struct iovec ktriov;
  746         struct uio *ktruioin = NULL;
  747         struct uio *ktruioout = NULL;
  748 #endif
  749 
  750         if (uap->timeout != NULL) {
  751                 error = copyin(uap->timeout, &ts, sizeof(ts));
  752                 if (error)
  753                         return (error);
  754                 tsp = &ts;
  755         } else
  756                 tsp = NULL;
  757 
  758 #ifdef KTRACE
  759         if (KTRPOINT(td, KTR_GENIO)) {
  760                 ktriov.iov_base = uap->changelist;
  761                 ktriov.iov_len = uap->nchanges * sizeof(struct kevent);
  762                 ktruio = (struct uio){ .uio_iov = &ktriov, .uio_iovcnt = 1,
  763                     .uio_segflg = UIO_USERSPACE, .uio_rw = UIO_READ,
  764                     .uio_td = td };
  765                 ktruioin = cloneuio(&ktruio);
  766                 ktriov.iov_base = uap->eventlist;
  767                 ktriov.iov_len = uap->nevents * sizeof(struct kevent);
  768                 ktruioout = cloneuio(&ktruio);
  769         }
  770 #endif
  771 
  772         error = kern_kevent(td, uap->fd, uap->nchanges, uap->nevents,
  773             &k_ops, tsp);
  774 
  775 #ifdef KTRACE
  776         if (ktruioin != NULL) {
  777                 ktruioin->uio_resid = uap->nchanges * sizeof(struct kevent);
  778                 ktrgenio(uap->fd, UIO_WRITE, ktruioin, 0);
  779                 ktruioout->uio_resid = td->td_retval[0] * sizeof(struct kevent);
  780                 ktrgenio(uap->fd, UIO_READ, ktruioout, error);
  781         }
  782 #endif
  783 
  784         return (error);
  785 }
  786 
  787 /*
  788  * Copy 'count' items into the destination list pointed to by uap->eventlist.
  789  */
  790 static int
  791 kevent_copyout(void *arg, struct kevent *kevp, int count)
  792 {
  793         struct kevent_args *uap;
  794         int error;
  795 
  796         KASSERT(count <= KQ_NEVENTS, ("count (%d) > KQ_NEVENTS", count));
  797         uap = (struct kevent_args *)arg;
  798 
  799         error = copyout(kevp, uap->eventlist, count * sizeof *kevp);
  800         if (error == 0)
  801                 uap->eventlist += count;
  802         return (error);
  803 }
  804 
  805 /*
  806  * Copy 'count' items from the list pointed to by uap->changelist.
  807  */
  808 static int
  809 kevent_copyin(void *arg, struct kevent *kevp, int count)
  810 {
  811         struct kevent_args *uap;
  812         int error;
  813 
  814         KASSERT(count <= KQ_NEVENTS, ("count (%d) > KQ_NEVENTS", count));
  815         uap = (struct kevent_args *)arg;
  816 
  817         error = copyin(uap->changelist, kevp, count * sizeof *kevp);
  818         if (error == 0)
  819                 uap->changelist += count;
  820         return (error);
  821 }
  822 
  823 int
  824 kern_kevent(struct thread *td, int fd, int nchanges, int nevents,
  825     struct kevent_copyops *k_ops, const struct timespec *timeout)
  826 {
  827         struct kevent keva[KQ_NEVENTS];
  828         struct kevent *kevp, *changes;
  829         struct kqueue *kq;
  830         struct file *fp;
  831         int i, n, nerrors, error;
  832 
  833         if ((error = fget(td, fd, CAP_POST_EVENT, &fp)) != 0)
  834                 return (error);
  835         if ((error = kqueue_acquire(fp, &kq)) != 0)
  836                 goto done_norel;
  837 
  838         nerrors = 0;
  839 
  840         while (nchanges > 0) {
  841                 n = nchanges > KQ_NEVENTS ? KQ_NEVENTS : nchanges;
  842                 error = k_ops->k_copyin(k_ops->arg, keva, n);
  843                 if (error)
  844                         goto done;
  845                 changes = keva;
  846                 for (i = 0; i < n; i++) {
  847                         kevp = &changes[i];
  848                         if (!kevp->filter)
  849                                 continue;
  850                         kevp->flags &= ~EV_SYSFLAGS;
  851                         error = kqueue_register(kq, kevp, td, 1);
  852                         if (error || (kevp->flags & EV_RECEIPT)) {
  853                                 if (nevents != 0) {
  854                                         kevp->flags = EV_ERROR;
  855                                         kevp->data = error;
  856                                         (void) k_ops->k_copyout(k_ops->arg,
  857                                             kevp, 1);
  858                                         nevents--;
  859                                         nerrors++;
  860                                 } else {
  861                                         goto done;
  862                                 }
  863                         }
  864                 }
  865                 nchanges -= n;
  866         }
  867         if (nerrors) {
  868                 td->td_retval[0] = nerrors;
  869                 error = 0;
  870                 goto done;
  871         }
  872 
  873         error = kqueue_scan(kq, nevents, k_ops, timeout, keva, td);
  874 done:
  875         kqueue_release(kq, 0);
  876 done_norel:
  877         fdrop(fp, td);
  878         return (error);
  879 }
  880 
  881 int
  882 kqueue_add_filteropts(int filt, struct filterops *filtops)
  883 {
  884         int error;
  885 
  886         error = 0;
  887         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0) {
  888                 printf(
  889 "trying to add a filterop that is out of range: %d is beyond %d\n",
  890                     ~filt, EVFILT_SYSCOUNT);
  891                 return EINVAL;
  892         }
  893         mtx_lock(&filterops_lock);
  894         if (sysfilt_ops[~filt].for_fop != &null_filtops &&
  895             sysfilt_ops[~filt].for_fop != NULL)
  896                 error = EEXIST;
  897         else {
  898                 sysfilt_ops[~filt].for_fop = filtops;
  899                 sysfilt_ops[~filt].for_refcnt = 0;
  900         }
  901         mtx_unlock(&filterops_lock);
  902 
  903         return (error);
  904 }
  905 
  906 int
  907 kqueue_del_filteropts(int filt)
  908 {
  909         int error;
  910 
  911         error = 0;
  912         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  913                 return EINVAL;
  914 
  915         mtx_lock(&filterops_lock);
  916         if (sysfilt_ops[~filt].for_fop == &null_filtops ||
  917             sysfilt_ops[~filt].for_fop == NULL)
  918                 error = EINVAL;
  919         else if (sysfilt_ops[~filt].for_refcnt != 0)
  920                 error = EBUSY;
  921         else {
  922                 sysfilt_ops[~filt].for_fop = &null_filtops;
  923                 sysfilt_ops[~filt].for_refcnt = 0;
  924         }
  925         mtx_unlock(&filterops_lock);
  926 
  927         return error;
  928 }
  929 
  930 static struct filterops *
  931 kqueue_fo_find(int filt)
  932 {
  933 
  934         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  935                 return NULL;
  936 
  937         mtx_lock(&filterops_lock);
  938         sysfilt_ops[~filt].for_refcnt++;
  939         if (sysfilt_ops[~filt].for_fop == NULL)
  940                 sysfilt_ops[~filt].for_fop = &null_filtops;
  941         mtx_unlock(&filterops_lock);
  942 
  943         return sysfilt_ops[~filt].for_fop;
  944 }
  945 
  946 static void
  947 kqueue_fo_release(int filt)
  948 {
  949 
  950         if (filt > 0 || filt + EVFILT_SYSCOUNT < 0)
  951                 return;
  952 
  953         mtx_lock(&filterops_lock);
  954         KASSERT(sysfilt_ops[~filt].for_refcnt > 0,
  955             ("filter object refcount not valid on release"));
  956         sysfilt_ops[~filt].for_refcnt--;
  957         mtx_unlock(&filterops_lock);
  958 }
  959 
  960 /*
  961  * A ref to kq (obtained via kqueue_acquire) must be held.  waitok will
  962  * influence if memory allocation should wait.  Make sure it is 0 if you
  963  * hold any mutexes.
  964  */
  965 static int
  966 kqueue_register(struct kqueue *kq, struct kevent *kev, struct thread *td, int waitok)
  967 {
  968         struct filterops *fops;
  969         struct file *fp;
  970         struct knote *kn, *tkn;
  971         int error, filt, event;
  972         int haskqglobal, filedesc_unlock;
  973 
  974         fp = NULL;
  975         kn = NULL;
  976         error = 0;
  977         haskqglobal = 0;
  978         filedesc_unlock = 0;
  979 
  980         filt = kev->filter;
  981         fops = kqueue_fo_find(filt);
  982         if (fops == NULL)
  983                 return EINVAL;
  984 
  985         tkn = knote_alloc(waitok);              /* prevent waiting with locks */
  986 
  987 findkn:
  988         if (fops->f_isfd) {
  989                 KASSERT(td != NULL, ("td is NULL"));
  990                 if (kev->ident > INT_MAX)
  991                         error = EBADF;
  992                 else
  993                         error = fget(td, kev->ident, CAP_POLL_EVENT, &fp);
  994                 if (error)
  995                         goto done;
  996 
  997                 if ((kev->flags & EV_ADD) == EV_ADD && kqueue_expand(kq, fops,
  998                     kev->ident, 0) != 0) {
  999                         /* try again */
 1000                         fdrop(fp, td);
 1001                         fp = NULL;
 1002                         error = kqueue_expand(kq, fops, kev->ident, waitok);
 1003                         if (error)
 1004                                 goto done;
 1005                         goto findkn;
 1006                 }
 1007 
 1008                 if (fp->f_type == DTYPE_KQUEUE) {
 1009                         /*
 1010                          * if we add some inteligence about what we are doing,
 1011                          * we should be able to support events on ourselves.
 1012                          * We need to know when we are doing this to prevent
 1013                          * getting both the knlist lock and the kq lock since
 1014                          * they are the same thing.
 1015                          */
 1016                         if (fp->f_data == kq) {
 1017                                 error = EINVAL;
 1018                                 goto done;
 1019                         }
 1020 
 1021                         /*
 1022                          * Pre-lock the filedesc before the global
 1023                          * lock mutex, see the comment in
 1024                          * kqueue_close().
 1025                          */
 1026                         FILEDESC_XLOCK(td->td_proc->p_fd);
 1027                         filedesc_unlock = 1;
 1028                         KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1029                 }
 1030 
 1031                 KQ_LOCK(kq);
 1032                 if (kev->ident < kq->kq_knlistsize) {
 1033                         SLIST_FOREACH(kn, &kq->kq_knlist[kev->ident], kn_link)
 1034                                 if (kev->filter == kn->kn_filter)
 1035                                         break;
 1036                 }
 1037         } else {
 1038                 if ((kev->flags & EV_ADD) == EV_ADD)
 1039                         kqueue_expand(kq, fops, kev->ident, waitok);
 1040 
 1041                 KQ_LOCK(kq);
 1042                 if (kq->kq_knhashmask != 0) {
 1043                         struct klist *list;
 1044 
 1045                         list = &kq->kq_knhash[
 1046                             KN_HASH((u_long)kev->ident, kq->kq_knhashmask)];
 1047                         SLIST_FOREACH(kn, list, kn_link)
 1048                                 if (kev->ident == kn->kn_id &&
 1049                                     kev->filter == kn->kn_filter)
 1050                                         break;
 1051                 }
 1052         }
 1053 
 1054         /* knote is in the process of changing, wait for it to stablize. */
 1055         if (kn != NULL && (kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1056                 KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1057                 if (filedesc_unlock) {
 1058                         FILEDESC_XUNLOCK(td->td_proc->p_fd);
 1059                         filedesc_unlock = 0;
 1060                 }
 1061                 kq->kq_state |= KQ_FLUXWAIT;
 1062                 msleep(kq, &kq->kq_lock, PSOCK | PDROP, "kqflxwt", 0);
 1063                 if (fp != NULL) {
 1064                         fdrop(fp, td);
 1065                         fp = NULL;
 1066                 }
 1067                 goto findkn;
 1068         }
 1069 
 1070         /*
 1071          * kn now contains the matching knote, or NULL if no match
 1072          */
 1073         if (kn == NULL) {
 1074                 if (kev->flags & EV_ADD) {
 1075                         kn = tkn;
 1076                         tkn = NULL;
 1077                         if (kn == NULL) {
 1078                                 KQ_UNLOCK(kq);
 1079                                 error = ENOMEM;
 1080                                 goto done;
 1081                         }
 1082                         kn->kn_fp = fp;
 1083                         kn->kn_kq = kq;
 1084                         kn->kn_fop = fops;
 1085                         /*
 1086                          * apply reference counts to knote structure, and
 1087                          * do not release it at the end of this routine.
 1088                          */
 1089                         fops = NULL;
 1090                         fp = NULL;
 1091 
 1092                         kn->kn_sfflags = kev->fflags;
 1093                         kn->kn_sdata = kev->data;
 1094                         kev->fflags = 0;
 1095                         kev->data = 0;
 1096                         kn->kn_kevent = *kev;
 1097                         kn->kn_kevent.flags &= ~(EV_ADD | EV_DELETE |
 1098                             EV_ENABLE | EV_DISABLE);
 1099                         kn->kn_status = KN_INFLUX|KN_DETACHED;
 1100 
 1101                         error = knote_attach(kn, kq);
 1102                         KQ_UNLOCK(kq);
 1103                         if (error != 0) {
 1104                                 tkn = kn;
 1105                                 goto done;
 1106                         }
 1107 
 1108                         if ((error = kn->kn_fop->f_attach(kn)) != 0) {
 1109                                 knote_drop(kn, td);
 1110                                 goto done;
 1111                         }
 1112                         KN_LIST_LOCK(kn);
 1113                         goto done_ev_add;
 1114                 } else {
 1115                         /* No matching knote and the EV_ADD flag is not set. */
 1116                         KQ_UNLOCK(kq);
 1117                         error = ENOENT;
 1118                         goto done;
 1119                 }
 1120         }
 1121         
 1122         if (kev->flags & EV_DELETE) {
 1123                 kn->kn_status |= KN_INFLUX;
 1124                 KQ_UNLOCK(kq);
 1125                 if (!(kn->kn_status & KN_DETACHED))
 1126                         kn->kn_fop->f_detach(kn);
 1127                 knote_drop(kn, td);
 1128                 goto done;
 1129         }
 1130 
 1131         /*
 1132          * The user may change some filter values after the initial EV_ADD,
 1133          * but doing so will not reset any filter which has already been
 1134          * triggered.
 1135          */
 1136         kn->kn_status |= KN_INFLUX | KN_SCAN;
 1137         KQ_UNLOCK(kq);
 1138         KN_LIST_LOCK(kn);
 1139         kn->kn_kevent.udata = kev->udata;
 1140         if (!fops->f_isfd && fops->f_touch != NULL) {
 1141                 fops->f_touch(kn, kev, EVENT_REGISTER);
 1142         } else {
 1143                 kn->kn_sfflags = kev->fflags;
 1144                 kn->kn_sdata = kev->data;
 1145         }
 1146 
 1147         /*
 1148          * We can get here with kn->kn_knlist == NULL.  This can happen when
 1149          * the initial attach event decides that the event is "completed" 
 1150          * already.  i.e. filt_procattach is called on a zombie process.  It
 1151          * will call filt_proc which will remove it from the list, and NULL
 1152          * kn_knlist.
 1153          */
 1154 done_ev_add:
 1155         event = kn->kn_fop->f_event(kn, 0);
 1156         KQ_LOCK(kq);
 1157         if (event)
 1158                 KNOTE_ACTIVATE(kn, 1);
 1159         kn->kn_status &= ~(KN_INFLUX | KN_SCAN);
 1160         KN_LIST_UNLOCK(kn);
 1161 
 1162         if ((kev->flags & EV_DISABLE) &&
 1163             ((kn->kn_status & KN_DISABLED) == 0)) {
 1164                 kn->kn_status |= KN_DISABLED;
 1165         }
 1166 
 1167         if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
 1168                 kn->kn_status &= ~KN_DISABLED;
 1169                 if ((kn->kn_status & KN_ACTIVE) &&
 1170                     ((kn->kn_status & KN_QUEUED) == 0))
 1171                         knote_enqueue(kn);
 1172         }
 1173         KQ_UNLOCK_FLUX(kq);
 1174 
 1175 done:
 1176         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1177         if (filedesc_unlock)
 1178                 FILEDESC_XUNLOCK(td->td_proc->p_fd);
 1179         if (fp != NULL)
 1180                 fdrop(fp, td);
 1181         if (tkn != NULL)
 1182                 knote_free(tkn);
 1183         if (fops != NULL)
 1184                 kqueue_fo_release(filt);
 1185         return (error);
 1186 }
 1187 
 1188 static int
 1189 kqueue_acquire(struct file *fp, struct kqueue **kqp)
 1190 {
 1191         int error;
 1192         struct kqueue *kq;
 1193 
 1194         error = 0;
 1195 
 1196         kq = fp->f_data;
 1197         if (fp->f_type != DTYPE_KQUEUE || kq == NULL)
 1198                 return (EBADF);
 1199         *kqp = kq;
 1200         KQ_LOCK(kq);
 1201         if ((kq->kq_state & KQ_CLOSING) == KQ_CLOSING) {
 1202                 KQ_UNLOCK(kq);
 1203                 return (EBADF);
 1204         }
 1205         kq->kq_refcnt++;
 1206         KQ_UNLOCK(kq);
 1207 
 1208         return error;
 1209 }
 1210 
 1211 static void
 1212 kqueue_release(struct kqueue *kq, int locked)
 1213 {
 1214         if (locked)
 1215                 KQ_OWNED(kq);
 1216         else
 1217                 KQ_LOCK(kq);
 1218         kq->kq_refcnt--;
 1219         if (kq->kq_refcnt == 1)
 1220                 wakeup(&kq->kq_refcnt);
 1221         if (!locked)
 1222                 KQ_UNLOCK(kq);
 1223 }
 1224 
 1225 static void
 1226 kqueue_schedtask(struct kqueue *kq)
 1227 {
 1228 
 1229         KQ_OWNED(kq);
 1230         KASSERT(((kq->kq_state & KQ_TASKDRAIN) != KQ_TASKDRAIN),
 1231             ("scheduling kqueue task while draining"));
 1232 
 1233         if ((kq->kq_state & KQ_TASKSCHED) != KQ_TASKSCHED) {
 1234                 taskqueue_enqueue(taskqueue_kqueue, &kq->kq_task);
 1235                 kq->kq_state |= KQ_TASKSCHED;
 1236         }
 1237 }
 1238 
 1239 /*
 1240  * Expand the kq to make sure we have storage for fops/ident pair.
 1241  *
 1242  * Return 0 on success (or no work necessary), return errno on failure.
 1243  *
 1244  * Not calling hashinit w/ waitok (proper malloc flag) should be safe.
 1245  * If kqueue_register is called from a non-fd context, there usually/should
 1246  * be no locks held.
 1247  */
 1248 static int
 1249 kqueue_expand(struct kqueue *kq, struct filterops *fops, uintptr_t ident,
 1250         int waitok)
 1251 {
 1252         struct klist *list, *tmp_knhash, *to_free;
 1253         u_long tmp_knhashmask;
 1254         int size;
 1255         int fd;
 1256         int mflag = waitok ? M_WAITOK : M_NOWAIT;
 1257 
 1258         KQ_NOTOWNED(kq);
 1259 
 1260         to_free = NULL;
 1261         if (fops->f_isfd) {
 1262                 fd = ident;
 1263                 if (kq->kq_knlistsize <= fd) {
 1264                         size = kq->kq_knlistsize;
 1265                         while (size <= fd)
 1266                                 size += KQEXTENT;
 1267                         list = malloc(size * sizeof(*list), M_KQUEUE, mflag);
 1268                         if (list == NULL)
 1269                                 return ENOMEM;
 1270                         KQ_LOCK(kq);
 1271                         if (kq->kq_knlistsize > fd) {
 1272                                 to_free = list;
 1273                                 list = NULL;
 1274                         } else {
 1275                                 if (kq->kq_knlist != NULL) {
 1276                                         bcopy(kq->kq_knlist, list,
 1277                                             kq->kq_knlistsize * sizeof(*list));
 1278                                         to_free = kq->kq_knlist;
 1279                                         kq->kq_knlist = NULL;
 1280                                 }
 1281                                 bzero((caddr_t)list +
 1282                                     kq->kq_knlistsize * sizeof(*list),
 1283                                     (size - kq->kq_knlistsize) * sizeof(*list));
 1284                                 kq->kq_knlistsize = size;
 1285                                 kq->kq_knlist = list;
 1286                         }
 1287                         KQ_UNLOCK(kq);
 1288                 }
 1289         } else {
 1290                 if (kq->kq_knhashmask == 0) {
 1291                         tmp_knhash = hashinit(KN_HASHSIZE, M_KQUEUE,
 1292                             &tmp_knhashmask);
 1293                         if (tmp_knhash == NULL)
 1294                                 return ENOMEM;
 1295                         KQ_LOCK(kq);
 1296                         if (kq->kq_knhashmask == 0) {
 1297                                 kq->kq_knhash = tmp_knhash;
 1298                                 kq->kq_knhashmask = tmp_knhashmask;
 1299                         } else {
 1300                                 to_free = tmp_knhash;
 1301                         }
 1302                         KQ_UNLOCK(kq);
 1303                 }
 1304         }
 1305         free(to_free, M_KQUEUE);
 1306 
 1307         KQ_NOTOWNED(kq);
 1308         return 0;
 1309 }
 1310 
 1311 static void
 1312 kqueue_task(void *arg, int pending)
 1313 {
 1314         struct kqueue *kq;
 1315         int haskqglobal;
 1316 
 1317         haskqglobal = 0;
 1318         kq = arg;
 1319 
 1320         KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1321         KQ_LOCK(kq);
 1322 
 1323         KNOTE_LOCKED(&kq->kq_sel.si_note, 0);
 1324 
 1325         kq->kq_state &= ~KQ_TASKSCHED;
 1326         if ((kq->kq_state & KQ_TASKDRAIN) == KQ_TASKDRAIN) {
 1327                 wakeup(&kq->kq_state);
 1328         }
 1329         KQ_UNLOCK(kq);
 1330         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1331 }
 1332 
 1333 /*
 1334  * Scan, update kn_data (if not ONESHOT), and copyout triggered events.
 1335  * We treat KN_MARKER knotes as if they are INFLUX.
 1336  */
 1337 static int
 1338 kqueue_scan(struct kqueue *kq, int maxevents, struct kevent_copyops *k_ops,
 1339     const struct timespec *tsp, struct kevent *keva, struct thread *td)
 1340 {
 1341         struct kevent *kevp;
 1342         struct timeval atv, rtv, ttv;
 1343         struct knote *kn, *marker;
 1344         int count, timeout, nkev, error, influx;
 1345         int haskqglobal, touch;
 1346 
 1347         count = maxevents;
 1348         nkev = 0;
 1349         error = 0;
 1350         haskqglobal = 0;
 1351 
 1352         if (maxevents == 0)
 1353                 goto done_nl;
 1354 
 1355         if (tsp != NULL) {
 1356                 TIMESPEC_TO_TIMEVAL(&atv, tsp);
 1357                 if (itimerfix(&atv)) {
 1358                         error = EINVAL;
 1359                         goto done_nl;
 1360                 }
 1361                 if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
 1362                         timeout = -1;
 1363                 else
 1364                         timeout = atv.tv_sec > 24 * 60 * 60 ?
 1365                             24 * 60 * 60 * hz : tvtohz(&atv);
 1366                 getmicrouptime(&rtv);
 1367                 timevaladd(&atv, &rtv);
 1368         } else {
 1369                 atv.tv_sec = 0;
 1370                 atv.tv_usec = 0;
 1371                 timeout = 0;
 1372         }
 1373         marker = knote_alloc(1);
 1374         if (marker == NULL) {
 1375                 error = ENOMEM;
 1376                 goto done_nl;
 1377         }
 1378         marker->kn_status = KN_MARKER;
 1379         KQ_LOCK(kq);
 1380         goto start;
 1381 
 1382 retry:
 1383         if (atv.tv_sec || atv.tv_usec) {
 1384                 getmicrouptime(&rtv);
 1385                 if (timevalcmp(&rtv, &atv, >=))
 1386                         goto done;
 1387                 ttv = atv;
 1388                 timevalsub(&ttv, &rtv);
 1389                 timeout = ttv.tv_sec > 24 * 60 * 60 ?
 1390                         24 * 60 * 60 * hz : tvtohz(&ttv);
 1391         }
 1392 
 1393 start:
 1394         kevp = keva;
 1395         if (kq->kq_count == 0) {
 1396                 if (timeout < 0) {
 1397                         error = EWOULDBLOCK;
 1398                 } else {
 1399                         kq->kq_state |= KQ_SLEEP;
 1400                         error = msleep(kq, &kq->kq_lock, PSOCK | PCATCH,
 1401                             "kqread", timeout);
 1402                 }
 1403                 if (error == 0)
 1404                         goto retry;
 1405                 /* don't restart after signals... */
 1406                 if (error == ERESTART)
 1407                         error = EINTR;
 1408                 else if (error == EWOULDBLOCK)
 1409                         error = 0;
 1410                 goto done;
 1411         }
 1412 
 1413         TAILQ_INSERT_TAIL(&kq->kq_head, marker, kn_tqe);
 1414         influx = 0;
 1415         while (count) {
 1416                 KQ_OWNED(kq);
 1417                 kn = TAILQ_FIRST(&kq->kq_head);
 1418 
 1419                 if ((kn->kn_status == KN_MARKER && kn != marker) ||
 1420                     (kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1421                         if (influx) {
 1422                                 influx = 0;
 1423                                 KQ_FLUX_WAKEUP(kq);
 1424                         }
 1425                         kq->kq_state |= KQ_FLUXWAIT;
 1426                         error = msleep(kq, &kq->kq_lock, PSOCK,
 1427                             "kqflxwt", 0);
 1428                         continue;
 1429                 }
 1430 
 1431                 TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
 1432                 if ((kn->kn_status & KN_DISABLED) == KN_DISABLED) {
 1433                         kn->kn_status &= ~KN_QUEUED;
 1434                         kq->kq_count--;
 1435                         continue;
 1436                 }
 1437                 if (kn == marker) {
 1438                         KQ_FLUX_WAKEUP(kq);
 1439                         if (count == maxevents)
 1440                                 goto retry;
 1441                         goto done;
 1442                 }
 1443                 KASSERT((kn->kn_status & KN_INFLUX) == 0,
 1444                     ("KN_INFLUX set when not suppose to be"));
 1445 
 1446                 if ((kn->kn_flags & EV_DROP) == EV_DROP) {
 1447                         kn->kn_status &= ~KN_QUEUED;
 1448                         kn->kn_status |= KN_INFLUX;
 1449                         kq->kq_count--;
 1450                         KQ_UNLOCK(kq);
 1451                         /*
 1452                          * We don't need to lock the list since we've marked
 1453                          * it _INFLUX.
 1454                          */
 1455                         if (!(kn->kn_status & KN_DETACHED))
 1456                                 kn->kn_fop->f_detach(kn);
 1457                         knote_drop(kn, td);
 1458                         KQ_LOCK(kq);
 1459                         continue;
 1460                 } else if ((kn->kn_flags & EV_ONESHOT) == EV_ONESHOT) {
 1461                         kn->kn_status &= ~KN_QUEUED;
 1462                         kn->kn_status |= KN_INFLUX;
 1463                         kq->kq_count--;
 1464                         KQ_UNLOCK(kq);
 1465                         /*
 1466                          * We don't need to lock the list since we've marked
 1467                          * it _INFLUX.
 1468                          */
 1469                         *kevp = kn->kn_kevent;
 1470                         if (!(kn->kn_status & KN_DETACHED))
 1471                                 kn->kn_fop->f_detach(kn);
 1472                         knote_drop(kn, td);
 1473                         KQ_LOCK(kq);
 1474                         kn = NULL;
 1475                 } else {
 1476                         kn->kn_status |= KN_INFLUX | KN_SCAN;
 1477                         KQ_UNLOCK(kq);
 1478                         if ((kn->kn_status & KN_KQUEUE) == KN_KQUEUE)
 1479                                 KQ_GLOBAL_LOCK(&kq_global, haskqglobal);
 1480                         KN_LIST_LOCK(kn);
 1481                         if (kn->kn_fop->f_event(kn, 0) == 0) {
 1482                                 KQ_LOCK(kq);
 1483                                 KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1484                                 kn->kn_status &=
 1485                                     ~(KN_QUEUED | KN_ACTIVE | KN_INFLUX |
 1486                                     KN_SCAN);
 1487                                 kq->kq_count--;
 1488                                 KN_LIST_UNLOCK(kn);
 1489                                 influx = 1;
 1490                                 continue;
 1491                         }
 1492                         touch = (!kn->kn_fop->f_isfd &&
 1493                             kn->kn_fop->f_touch != NULL);
 1494                         if (touch)
 1495                                 kn->kn_fop->f_touch(kn, kevp, EVENT_PROCESS);
 1496                         else
 1497                                 *kevp = kn->kn_kevent;
 1498                         KQ_LOCK(kq);
 1499                         KQ_GLOBAL_UNLOCK(&kq_global, haskqglobal);
 1500                         if (kn->kn_flags & (EV_CLEAR |  EV_DISPATCH)) {
 1501                                 /* 
 1502                                  * Manually clear knotes who weren't 
 1503                                  * 'touch'ed.
 1504                                  */
 1505                                 if (touch == 0 && kn->kn_flags & EV_CLEAR) {
 1506                                         kn->kn_data = 0;
 1507                                         kn->kn_fflags = 0;
 1508                                 }
 1509                                 if (kn->kn_flags & EV_DISPATCH)
 1510                                         kn->kn_status |= KN_DISABLED;
 1511                                 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
 1512                                 kq->kq_count--;
 1513                         } else
 1514                                 TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
 1515                         
 1516                         kn->kn_status &= ~(KN_INFLUX | KN_SCAN);
 1517                         KN_LIST_UNLOCK(kn);
 1518                         influx = 1;
 1519                 }
 1520 
 1521                 /* we are returning a copy to the user */
 1522                 kevp++;
 1523                 nkev++;
 1524                 count--;
 1525 
 1526                 if (nkev == KQ_NEVENTS) {
 1527                         influx = 0;
 1528                         KQ_UNLOCK_FLUX(kq);
 1529                         error = k_ops->k_copyout(k_ops->arg, keva, nkev);
 1530                         nkev = 0;
 1531                         kevp = keva;
 1532                         KQ_LOCK(kq);
 1533                         if (error)
 1534                                 break;
 1535                 }
 1536         }
 1537         TAILQ_REMOVE(&kq->kq_head, marker, kn_tqe);
 1538 done:
 1539         KQ_OWNED(kq);
 1540         KQ_UNLOCK_FLUX(kq);
 1541         knote_free(marker);
 1542 done_nl:
 1543         KQ_NOTOWNED(kq);
 1544         if (nkev != 0)
 1545                 error = k_ops->k_copyout(k_ops->arg, keva, nkev);
 1546         td->td_retval[0] = maxevents - count;
 1547         return (error);
 1548 }
 1549 
 1550 /*
 1551  * XXX
 1552  * This could be expanded to call kqueue_scan, if desired.
 1553  */
 1554 /*ARGSUSED*/
 1555 static int
 1556 kqueue_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1557         int flags, struct thread *td)
 1558 {
 1559         return (ENXIO);
 1560 }
 1561 
 1562 /*ARGSUSED*/
 1563 static int
 1564 kqueue_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
 1565          int flags, struct thread *td)
 1566 {
 1567         return (ENXIO);
 1568 }
 1569 
 1570 /*ARGSUSED*/
 1571 static int
 1572 kqueue_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 1573         struct thread *td)
 1574 {
 1575 
 1576         return (EINVAL);
 1577 }
 1578 
 1579 /*ARGSUSED*/
 1580 static int
 1581 kqueue_ioctl(struct file *fp, u_long cmd, void *data,
 1582         struct ucred *active_cred, struct thread *td)
 1583 {
 1584         /*
 1585          * Enabling sigio causes two major problems:
 1586          * 1) infinite recursion:
 1587          * Synopsys: kevent is being used to track signals and have FIOASYNC
 1588          * set.  On receipt of a signal this will cause a kqueue to recurse
 1589          * into itself over and over.  Sending the sigio causes the kqueue
 1590          * to become ready, which in turn posts sigio again, forever.
 1591          * Solution: this can be solved by setting a flag in the kqueue that
 1592          * we have a SIGIO in progress.
 1593          * 2) locking problems:
 1594          * Synopsys: Kqueue is a leaf subsystem, but adding signalling puts
 1595          * us above the proc and pgrp locks.
 1596          * Solution: Post a signal using an async mechanism, being sure to
 1597          * record a generation count in the delivery so that we do not deliver
 1598          * a signal to the wrong process.
 1599          *
 1600          * Note, these two mechanisms are somewhat mutually exclusive!
 1601          */
 1602 #if 0
 1603         struct kqueue *kq;
 1604 
 1605         kq = fp->f_data;
 1606         switch (cmd) {
 1607         case FIOASYNC:
 1608                 if (*(int *)data) {
 1609                         kq->kq_state |= KQ_ASYNC;
 1610                 } else {
 1611                         kq->kq_state &= ~KQ_ASYNC;
 1612                 }
 1613                 return (0);
 1614 
 1615         case FIOSETOWN:
 1616                 return (fsetown(*(int *)data, &kq->kq_sigio));
 1617 
 1618         case FIOGETOWN:
 1619                 *(int *)data = fgetown(&kq->kq_sigio);
 1620                 return (0);
 1621         }
 1622 #endif
 1623 
 1624         return (ENOTTY);
 1625 }
 1626 
 1627 /*ARGSUSED*/
 1628 static int
 1629 kqueue_poll(struct file *fp, int events, struct ucred *active_cred,
 1630         struct thread *td)
 1631 {
 1632         struct kqueue *kq;
 1633         int revents = 0;
 1634         int error;
 1635 
 1636         if ((error = kqueue_acquire(fp, &kq)))
 1637                 return POLLERR;
 1638 
 1639         KQ_LOCK(kq);
 1640         if (events & (POLLIN | POLLRDNORM)) {
 1641                 if (kq->kq_count) {
 1642                         revents |= events & (POLLIN | POLLRDNORM);
 1643                 } else {
 1644                         selrecord(td, &kq->kq_sel);
 1645                         if (SEL_WAITING(&kq->kq_sel))
 1646                                 kq->kq_state |= KQ_SEL;
 1647                 }
 1648         }
 1649         kqueue_release(kq, 1);
 1650         KQ_UNLOCK(kq);
 1651         return (revents);
 1652 }
 1653 
 1654 /*ARGSUSED*/
 1655 static int
 1656 kqueue_stat(struct file *fp, struct stat *st, struct ucred *active_cred,
 1657         struct thread *td)
 1658 {
 1659 
 1660         bzero((void *)st, sizeof *st);
 1661         /*
 1662          * We no longer return kq_count because the unlocked value is useless.
 1663          * If you spent all this time getting the count, why not spend your
 1664          * syscall better by calling kevent?
 1665          *
 1666          * XXX - This is needed for libc_r.
 1667          */
 1668         st->st_mode = S_IFIFO;
 1669         return (0);
 1670 }
 1671 
 1672 /*ARGSUSED*/
 1673 static int
 1674 kqueue_close(struct file *fp, struct thread *td)
 1675 {
 1676         struct kqueue *kq = fp->f_data;
 1677         struct filedesc *fdp;
 1678         struct knote *kn;
 1679         int i;
 1680         int error;
 1681         int filedesc_unlock;
 1682 
 1683         if ((error = kqueue_acquire(fp, &kq)))
 1684                 return error;
 1685 
 1686         filedesc_unlock = 0;
 1687         KQ_LOCK(kq);
 1688 
 1689         KASSERT((kq->kq_state & KQ_CLOSING) != KQ_CLOSING,
 1690             ("kqueue already closing"));
 1691         kq->kq_state |= KQ_CLOSING;
 1692         if (kq->kq_refcnt > 1)
 1693                 msleep(&kq->kq_refcnt, &kq->kq_lock, PSOCK, "kqclose", 0);
 1694 
 1695         KASSERT(kq->kq_refcnt == 1, ("other refs are out there!"));
 1696         fdp = kq->kq_fdp;
 1697 
 1698         KASSERT(knlist_empty(&kq->kq_sel.si_note),
 1699             ("kqueue's knlist not empty"));
 1700 
 1701         for (i = 0; i < kq->kq_knlistsize; i++) {
 1702                 while ((kn = SLIST_FIRST(&kq->kq_knlist[i])) != NULL) {
 1703                         if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1704                                 kq->kq_state |= KQ_FLUXWAIT;
 1705                                 msleep(kq, &kq->kq_lock, PSOCK, "kqclo1", 0);
 1706                                 continue;
 1707                         }
 1708                         kn->kn_status |= KN_INFLUX;
 1709                         KQ_UNLOCK(kq);
 1710                         if (!(kn->kn_status & KN_DETACHED))
 1711                                 kn->kn_fop->f_detach(kn);
 1712                         knote_drop(kn, td);
 1713                         KQ_LOCK(kq);
 1714                 }
 1715         }
 1716         if (kq->kq_knhashmask != 0) {
 1717                 for (i = 0; i <= kq->kq_knhashmask; i++) {
 1718                         while ((kn = SLIST_FIRST(&kq->kq_knhash[i])) != NULL) {
 1719                                 if ((kn->kn_status & KN_INFLUX) == KN_INFLUX) {
 1720                                         kq->kq_state |= KQ_FLUXWAIT;
 1721                                         msleep(kq, &kq->kq_lock, PSOCK,
 1722                                                "kqclo2", 0);
 1723                                         continue;
 1724                                 }
 1725                                 kn->kn_status |= KN_INFLUX;
 1726                                 KQ_UNLOCK(kq);
 1727                                 if (!(kn->kn_status & KN_DETACHED))
 1728                                         kn->kn_fop->f_detach(kn);
 1729                                 knote_drop(kn, td);
 1730                                 KQ_LOCK(kq);
 1731                         }
 1732                 }
 1733         }
 1734 
 1735         if ((kq->kq_state & KQ_TASKSCHED) == KQ_TASKSCHED) {
 1736                 kq->kq_state |= KQ_TASKDRAIN;
 1737                 msleep(&kq->kq_state, &kq->kq_lock, PSOCK, "kqtqdr", 0);
 1738         }
 1739 
 1740         if ((kq->kq_state & KQ_SEL) == KQ_SEL) {
 1741                 selwakeuppri(&kq->kq_sel, PSOCK);
 1742                 if (!SEL_WAITING(&kq->kq_sel))
 1743                         kq->kq_state &= ~KQ_SEL;
 1744         }
 1745 
 1746         KQ_UNLOCK(kq);
 1747 
 1748         /*
 1749          * We could be called due to the knote_drop() doing fdrop(),
 1750          * called from kqueue_register().  In this case the global
 1751          * lock is owned, and filedesc sx is locked before, to not
 1752          * take the sleepable lock after non-sleepable.
 1753          */
 1754         if (!sx_xlocked(FILEDESC_LOCK(fdp))) {
 1755                 FILEDESC_XLOCK(fdp);
 1756                 filedesc_unlock = 1;
 1757         } else
 1758                 filedesc_unlock = 0;
 1759         TAILQ_REMOVE(&fdp->fd_kqlist, kq, kq_list);
 1760         if (filedesc_unlock)
 1761                 FILEDESC_XUNLOCK(fdp);
 1762 
 1763         seldrain(&kq->kq_sel);
 1764         knlist_destroy(&kq->kq_sel.si_note);
 1765         mtx_destroy(&kq->kq_lock);
 1766         kq->kq_fdp = NULL;
 1767 
 1768         if (kq->kq_knhash != NULL)
 1769                 free(kq->kq_knhash, M_KQUEUE);
 1770         if (kq->kq_knlist != NULL)
 1771                 free(kq->kq_knlist, M_KQUEUE);
 1772 
 1773         funsetown(&kq->kq_sigio);
 1774         free(kq, M_KQUEUE);
 1775         fp->f_data = NULL;
 1776 
 1777         return (0);
 1778 }
 1779 
 1780 static void
 1781 kqueue_wakeup(struct kqueue *kq)
 1782 {
 1783         KQ_OWNED(kq);
 1784 
 1785         if ((kq->kq_state & KQ_SLEEP) == KQ_SLEEP) {
 1786                 kq->kq_state &= ~KQ_SLEEP;
 1787                 wakeup(kq);
 1788         }
 1789         if ((kq->kq_state & KQ_SEL) == KQ_SEL) {
 1790                 selwakeuppri(&kq->kq_sel, PSOCK);
 1791                 if (!SEL_WAITING(&kq->kq_sel))
 1792                         kq->kq_state &= ~KQ_SEL;
 1793         }
 1794         if (!knlist_empty(&kq->kq_sel.si_note))
 1795                 kqueue_schedtask(kq);
 1796         if ((kq->kq_state & KQ_ASYNC) == KQ_ASYNC) {
 1797                 pgsigio(&kq->kq_sigio, SIGIO, 0);
 1798         }
 1799 }
 1800 
 1801 /*
 1802  * Walk down a list of knotes, activating them if their event has triggered.
 1803  *
 1804  * There is a possibility to optimize in the case of one kq watching another.
 1805  * Instead of scheduling a task to wake it up, you could pass enough state
 1806  * down the chain to make up the parent kqueue.  Make this code functional
 1807  * first.
 1808  */
 1809 void
 1810 knote(struct knlist *list, long hint, int lockflags)
 1811 {
 1812         struct kqueue *kq;
 1813         struct knote *kn;
 1814         int error;
 1815 
 1816         if (list == NULL)
 1817                 return;
 1818 
 1819         KNL_ASSERT_LOCK(list, lockflags & KNF_LISTLOCKED);
 1820 
 1821         if ((lockflags & KNF_LISTLOCKED) == 0)
 1822                 list->kl_lock(list->kl_lockarg); 
 1823 
 1824         /*
 1825          * If we unlock the list lock (and set KN_INFLUX), we can eliminate
 1826          * the kqueue scheduling, but this will introduce four
 1827          * lock/unlock's for each knote to test.  If we do, continue to use
 1828          * SLIST_FOREACH, SLIST_FOREACH_SAFE is not safe in our case, it is
 1829          * only safe if you want to remove the current item, which we are
 1830          * not doing.
 1831          */
 1832         SLIST_FOREACH(kn, &list->kl_list, kn_selnext) {
 1833                 kq = kn->kn_kq;
 1834                 KQ_LOCK(kq);
 1835                 if ((kn->kn_status & (KN_INFLUX | KN_SCAN)) == KN_INFLUX) {
 1836                         /*
 1837                          * Do not process the influx notes, except for
 1838                          * the influx coming from the kq unlock in the
 1839                          * kqueue_scan().  In the later case, we do
 1840                          * not interfere with the scan, since the code
 1841                          * fragment in kqueue_scan() locks the knlist,
 1842                          * and cannot proceed until we finished.
 1843                          */
 1844                         KQ_UNLOCK(kq);
 1845                 } else if ((lockflags & KNF_NOKQLOCK) != 0) {
 1846                         kn->kn_status |= KN_INFLUX;
 1847                         KQ_UNLOCK(kq);
 1848                         error = kn->kn_fop->f_event(kn, hint);
 1849                         KQ_LOCK(kq);
 1850                         kn->kn_status &= ~KN_INFLUX;
 1851                         if (error)
 1852                                 KNOTE_ACTIVATE(kn, 1);
 1853                         KQ_UNLOCK_FLUX(kq);
 1854                 } else {
 1855                         kn->kn_status |= KN_HASKQLOCK;
 1856                         if (kn->kn_fop->f_event(kn, hint))
 1857                                 KNOTE_ACTIVATE(kn, 1);
 1858                         kn->kn_status &= ~KN_HASKQLOCK;
 1859                         KQ_UNLOCK(kq);
 1860                 }
 1861         }
 1862         if ((lockflags & KNF_LISTLOCKED) == 0)
 1863                 list->kl_unlock(list->kl_lockarg); 
 1864 }
 1865 
 1866 /*
 1867  * add a knote to a knlist
 1868  */
 1869 void
 1870 knlist_add(struct knlist *knl, struct knote *kn, int islocked)
 1871 {
 1872         KNL_ASSERT_LOCK(knl, islocked);
 1873         KQ_NOTOWNED(kn->kn_kq);
 1874         KASSERT((kn->kn_status & (KN_INFLUX|KN_DETACHED)) ==
 1875             (KN_INFLUX|KN_DETACHED), ("knote not KN_INFLUX and KN_DETACHED"));
 1876         if (!islocked)
 1877                 knl->kl_lock(knl->kl_lockarg);
 1878         SLIST_INSERT_HEAD(&knl->kl_list, kn, kn_selnext);
 1879         if (!islocked)
 1880                 knl->kl_unlock(knl->kl_lockarg);
 1881         KQ_LOCK(kn->kn_kq);
 1882         kn->kn_knlist = knl;
 1883         kn->kn_status &= ~KN_DETACHED;
 1884         KQ_UNLOCK(kn->kn_kq);
 1885 }
 1886 
 1887 static void
 1888 knlist_remove_kq(struct knlist *knl, struct knote *kn, int knlislocked, int kqislocked)
 1889 {
 1890         KASSERT(!(!!kqislocked && !knlislocked), ("kq locked w/o knl locked"));
 1891         KNL_ASSERT_LOCK(knl, knlislocked);
 1892         mtx_assert(&kn->kn_kq->kq_lock, kqislocked ? MA_OWNED : MA_NOTOWNED);
 1893         if (!kqislocked)
 1894                 KASSERT((kn->kn_status & (KN_INFLUX|KN_DETACHED)) == KN_INFLUX,
 1895     ("knlist_remove called w/o knote being KN_INFLUX or already removed"));
 1896         if (!knlislocked)
 1897                 knl->kl_lock(knl->kl_lockarg);
 1898         SLIST_REMOVE(&knl->kl_list, kn, knote, kn_selnext);
 1899         kn->kn_knlist = NULL;
 1900         if (!knlislocked)
 1901                 knl->kl_unlock(knl->kl_lockarg);
 1902         if (!kqislocked)
 1903                 KQ_LOCK(kn->kn_kq);
 1904         kn->kn_status |= KN_DETACHED;
 1905         if (!kqislocked)
 1906                 KQ_UNLOCK(kn->kn_kq);
 1907 }
 1908 
 1909 /*
 1910  * remove all knotes from a specified klist
 1911  */
 1912 void
 1913 knlist_remove(struct knlist *knl, struct knote *kn, int islocked)
 1914 {
 1915 
 1916         knlist_remove_kq(knl, kn, islocked, 0);
 1917 }
 1918 
 1919 /*
 1920  * remove knote from a specified klist while in f_event handler.
 1921  */
 1922 void
 1923 knlist_remove_inevent(struct knlist *knl, struct knote *kn)
 1924 {
 1925 
 1926         knlist_remove_kq(knl, kn, 1,
 1927             (kn->kn_status & KN_HASKQLOCK) == KN_HASKQLOCK);
 1928 }
 1929 
 1930 int
 1931 knlist_empty(struct knlist *knl)
 1932 {
 1933         KNL_ASSERT_LOCKED(knl);
 1934         return SLIST_EMPTY(&knl->kl_list);
 1935 }
 1936 
 1937 static struct mtx       knlist_lock;
 1938 MTX_SYSINIT(knlist_lock, &knlist_lock, "knlist lock for lockless objects",
 1939         MTX_DEF);
 1940 static void knlist_mtx_lock(void *arg);
 1941 static void knlist_mtx_unlock(void *arg);
 1942 
 1943 static void
 1944 knlist_mtx_lock(void *arg)
 1945 {
 1946         mtx_lock((struct mtx *)arg);
 1947 }
 1948 
 1949 static void
 1950 knlist_mtx_unlock(void *arg)
 1951 {
 1952         mtx_unlock((struct mtx *)arg);
 1953 }
 1954 
 1955 static void
 1956 knlist_mtx_assert_locked(void *arg)
 1957 {
 1958         mtx_assert((struct mtx *)arg, MA_OWNED);
 1959 }
 1960 
 1961 static void
 1962 knlist_mtx_assert_unlocked(void *arg)
 1963 {
 1964         mtx_assert((struct mtx *)arg, MA_NOTOWNED);
 1965 }
 1966 
 1967 void
 1968 knlist_init(struct knlist *knl, void *lock, void (*kl_lock)(void *),
 1969     void (*kl_unlock)(void *),
 1970     void (*kl_assert_locked)(void *), void (*kl_assert_unlocked)(void *))
 1971 {
 1972 
 1973         if (lock == NULL)
 1974                 knl->kl_lockarg = &knlist_lock;
 1975         else
 1976                 knl->kl_lockarg = lock;
 1977 
 1978         if (kl_lock == NULL)
 1979                 knl->kl_lock = knlist_mtx_lock;
 1980         else
 1981                 knl->kl_lock = kl_lock;
 1982         if (kl_unlock == NULL)
 1983                 knl->kl_unlock = knlist_mtx_unlock;
 1984         else
 1985                 knl->kl_unlock = kl_unlock;
 1986         if (kl_assert_locked == NULL)
 1987                 knl->kl_assert_locked = knlist_mtx_assert_locked;
 1988         else
 1989                 knl->kl_assert_locked = kl_assert_locked;
 1990         if (kl_assert_unlocked == NULL)
 1991                 knl->kl_assert_unlocked = knlist_mtx_assert_unlocked;
 1992         else
 1993                 knl->kl_assert_unlocked = kl_assert_unlocked;
 1994 
 1995         SLIST_INIT(&knl->kl_list);
 1996 }
 1997 
 1998 void
 1999 knlist_init_mtx(struct knlist *knl, struct mtx *lock)
 2000 {
 2001 
 2002         knlist_init(knl, lock, NULL, NULL, NULL, NULL);
 2003 }
 2004 
 2005 void
 2006 knlist_destroy(struct knlist *knl)
 2007 {
 2008 
 2009 #ifdef INVARIANTS
 2010         /*
 2011          * if we run across this error, we need to find the offending
 2012          * driver and have it call knlist_clear.
 2013          */
 2014         if (!SLIST_EMPTY(&knl->kl_list))
 2015                 printf("WARNING: destroying knlist w/ knotes on it!\n");
 2016 #endif
 2017 
 2018         knl->kl_lockarg = knl->kl_lock = knl->kl_unlock = NULL;
 2019         SLIST_INIT(&knl->kl_list);
 2020 }
 2021 
 2022 /*
 2023  * Even if we are locked, we may need to drop the lock to allow any influx
 2024  * knotes time to "settle".
 2025  */
 2026 void
 2027 knlist_cleardel(struct knlist *knl, struct thread *td, int islocked, int killkn)
 2028 {
 2029         struct knote *kn, *kn2;
 2030         struct kqueue *kq;
 2031 
 2032         if (islocked)
 2033                 KNL_ASSERT_LOCKED(knl);
 2034         else {
 2035                 KNL_ASSERT_UNLOCKED(knl);
 2036 again:          /* need to reacquire lock since we have dropped it */
 2037                 knl->kl_lock(knl->kl_lockarg);
 2038         }
 2039 
 2040         SLIST_FOREACH_SAFE(kn, &knl->kl_list, kn_selnext, kn2) {
 2041                 kq = kn->kn_kq;
 2042                 KQ_LOCK(kq);
 2043                 if ((kn->kn_status & KN_INFLUX)) {
 2044                         KQ_UNLOCK(kq);
 2045                         continue;
 2046                 }
 2047                 knlist_remove_kq(knl, kn, 1, 1);
 2048                 if (killkn) {
 2049                         kn->kn_status |= KN_INFLUX | KN_DETACHED;
 2050                         KQ_UNLOCK(kq);
 2051                         knote_drop(kn, td);
 2052                 } else {
 2053                         /* Make sure cleared knotes disappear soon */
 2054                         kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 2055                         KQ_UNLOCK(kq);
 2056                 }
 2057                 kq = NULL;
 2058         }
 2059 
 2060         if (!SLIST_EMPTY(&knl->kl_list)) {
 2061                 /* there are still KN_INFLUX remaining */
 2062                 kn = SLIST_FIRST(&knl->kl_list);
 2063                 kq = kn->kn_kq;
 2064                 KQ_LOCK(kq);
 2065                 KASSERT(kn->kn_status & KN_INFLUX,
 2066                     ("knote removed w/o list lock"));
 2067                 knl->kl_unlock(knl->kl_lockarg);
 2068                 kq->kq_state |= KQ_FLUXWAIT;
 2069                 msleep(kq, &kq->kq_lock, PSOCK | PDROP, "kqkclr", 0);
 2070                 kq = NULL;
 2071                 goto again;
 2072         }
 2073 
 2074         if (islocked)
 2075                 KNL_ASSERT_LOCKED(knl);
 2076         else {
 2077                 knl->kl_unlock(knl->kl_lockarg);
 2078                 KNL_ASSERT_UNLOCKED(knl);
 2079         }
 2080 }
 2081 
 2082 /*
 2083  * Remove all knotes referencing a specified fd must be called with FILEDESC
 2084  * lock.  This prevents a race where a new fd comes along and occupies the
 2085  * entry and we attach a knote to the fd.
 2086  */
 2087 void
 2088 knote_fdclose(struct thread *td, int fd)
 2089 {
 2090         struct filedesc *fdp = td->td_proc->p_fd;
 2091         struct kqueue *kq;
 2092         struct knote *kn;
 2093         int influx;
 2094 
 2095         FILEDESC_XLOCK_ASSERT(fdp);
 2096 
 2097         /*
 2098          * We shouldn't have to worry about new kevents appearing on fd
 2099          * since filedesc is locked.
 2100          */
 2101         TAILQ_FOREACH(kq, &fdp->fd_kqlist, kq_list) {
 2102                 KQ_LOCK(kq);
 2103 
 2104 again:
 2105                 influx = 0;
 2106                 while (kq->kq_knlistsize > fd &&
 2107                     (kn = SLIST_FIRST(&kq->kq_knlist[fd])) != NULL) {
 2108                         if (kn->kn_status & KN_INFLUX) {
 2109                                 /* someone else might be waiting on our knote */
 2110                                 if (influx)
 2111                                         wakeup(kq);
 2112                                 kq->kq_state |= KQ_FLUXWAIT;
 2113                                 msleep(kq, &kq->kq_lock, PSOCK, "kqflxwt", 0);
 2114                                 goto again;
 2115                         }
 2116                         kn->kn_status |= KN_INFLUX;
 2117                         KQ_UNLOCK(kq);
 2118                         if (!(kn->kn_status & KN_DETACHED))
 2119                                 kn->kn_fop->f_detach(kn);
 2120                         knote_drop(kn, td);
 2121                         influx = 1;
 2122                         KQ_LOCK(kq);
 2123                 }
 2124                 KQ_UNLOCK_FLUX(kq);
 2125         }
 2126 }
 2127 
 2128 static int
 2129 knote_attach(struct knote *kn, struct kqueue *kq)
 2130 {
 2131         struct klist *list;
 2132 
 2133         KASSERT(kn->kn_status & KN_INFLUX, ("knote not marked INFLUX"));
 2134         KQ_OWNED(kq);
 2135 
 2136         if (kn->kn_fop->f_isfd) {
 2137                 if (kn->kn_id >= kq->kq_knlistsize)
 2138                         return ENOMEM;
 2139                 list = &kq->kq_knlist[kn->kn_id];
 2140         } else {
 2141                 if (kq->kq_knhash == NULL)
 2142                         return ENOMEM;
 2143                 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
 2144         }
 2145 
 2146         SLIST_INSERT_HEAD(list, kn, kn_link);
 2147 
 2148         return 0;
 2149 }
 2150 
 2151 /*
 2152  * knote must already have been detached using the f_detach method.
 2153  * no lock need to be held, it is assumed that the KN_INFLUX flag is set
 2154  * to prevent other removal.
 2155  */
 2156 static void
 2157 knote_drop(struct knote *kn, struct thread *td)
 2158 {
 2159         struct kqueue *kq;
 2160         struct klist *list;
 2161 
 2162         kq = kn->kn_kq;
 2163 
 2164         KQ_NOTOWNED(kq);
 2165         KASSERT((kn->kn_status & KN_INFLUX) == KN_INFLUX,
 2166             ("knote_drop called without KN_INFLUX set in kn_status"));
 2167 
 2168         KQ_LOCK(kq);
 2169         if (kn->kn_fop->f_isfd)
 2170                 list = &kq->kq_knlist[kn->kn_id];
 2171         else
 2172                 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
 2173 
 2174         if (!SLIST_EMPTY(list))
 2175                 SLIST_REMOVE(list, kn, knote, kn_link);
 2176         if (kn->kn_status & KN_QUEUED)
 2177                 knote_dequeue(kn);
 2178         KQ_UNLOCK_FLUX(kq);
 2179 
 2180         if (kn->kn_fop->f_isfd) {
 2181                 fdrop(kn->kn_fp, td);
 2182                 kn->kn_fp = NULL;
 2183         }
 2184         kqueue_fo_release(kn->kn_kevent.filter);
 2185         kn->kn_fop = NULL;
 2186         knote_free(kn);
 2187 }
 2188 
 2189 static void
 2190 knote_enqueue(struct knote *kn)
 2191 {
 2192         struct kqueue *kq = kn->kn_kq;
 2193 
 2194         KQ_OWNED(kn->kn_kq);
 2195         KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued"));
 2196 
 2197         TAILQ_INSERT_TAIL(&kq->kq_head, kn, kn_tqe);
 2198         kn->kn_status |= KN_QUEUED;
 2199         kq->kq_count++;
 2200         kqueue_wakeup(kq);
 2201 }
 2202 
 2203 static void
 2204 knote_dequeue(struct knote *kn)
 2205 {
 2206         struct kqueue *kq = kn->kn_kq;
 2207 
 2208         KQ_OWNED(kn->kn_kq);
 2209         KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued"));
 2210 
 2211         TAILQ_REMOVE(&kq->kq_head, kn, kn_tqe);
 2212         kn->kn_status &= ~KN_QUEUED;
 2213         kq->kq_count--;
 2214 }
 2215 
 2216 static void
 2217 knote_init(void)
 2218 {
 2219 
 2220         knote_zone = uma_zcreate("KNOTE", sizeof(struct knote), NULL, NULL,
 2221             NULL, NULL, UMA_ALIGN_PTR, 0);
 2222 }
 2223 SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL);
 2224 
 2225 static struct knote *
 2226 knote_alloc(int waitok)
 2227 {
 2228         return ((struct knote *)uma_zalloc(knote_zone,
 2229             (waitok ? M_WAITOK : M_NOWAIT)|M_ZERO));
 2230 }
 2231 
 2232 static void
 2233 knote_free(struct knote *kn)
 2234 {
 2235         if (kn != NULL)
 2236                 uma_zfree(knote_zone, kn);
 2237 }
 2238 
 2239 /*
 2240  * Register the kev w/ the kq specified by fd.
 2241  */
 2242 int 
 2243 kqfd_register(int fd, struct kevent *kev, struct thread *td, int waitok)
 2244 {
 2245         struct kqueue *kq;
 2246         struct file *fp;
 2247         int error;
 2248 
 2249         if ((error = fget(td, fd, CAP_POST_EVENT, &fp)) != 0)
 2250                 return (error);
 2251         if ((error = kqueue_acquire(fp, &kq)) != 0)
 2252                 goto noacquire;
 2253 
 2254         error = kqueue_register(kq, kev, td, waitok);
 2255 
 2256         kqueue_release(kq, 0);
 2257 
 2258 noacquire:
 2259         fdrop(fp, td);
 2260 
 2261         return error;
 2262 }

Cache object: f90b136f78cfeb6eeceb5291ff2f8614


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