sys/kern/kern_event.c

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