1 /*- 2 * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/sys/kern/kern_event.c,v 1.2.2.10 2004/04/04 07:03:14 cperciva Exp $ 27 * $DragonFly: src/sys/kern/kern_event.c,v 1.33 2007/02/03 17:05:57 corecode Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/kernel.h> 33 #include <sys/proc.h> 34 #include <sys/malloc.h> 35 #include <sys/unistd.h> 36 #include <sys/file.h> 37 #include <sys/lock.h> 38 #include <sys/fcntl.h> 39 #include <sys/queue.h> 40 #include <sys/event.h> 41 #include <sys/eventvar.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/socketvar.h> 45 #include <sys/stat.h> 46 #include <sys/sysctl.h> 47 #include <sys/sysproto.h> 48 #include <sys/thread.h> 49 #include <sys/uio.h> 50 #include <sys/signalvar.h> 51 #include <sys/filio.h> 52 #include <sys/ktr.h> 53 54 #include <sys/thread2.h> 55 #include <sys/file2.h> 56 #include <sys/mplock2.h> 57 58 #include <vm/vm_zone.h> 59 60 /* 61 * Global token for kqueue subsystem 62 */ 63 struct lwkt_token kq_token = LWKT_TOKEN_UP_INITIALIZER(kq_token); 64 SYSCTL_INT(_lwkt, OID_AUTO, kq_mpsafe, 65 CTLFLAG_RW, &kq_token.t_flags, 0, ""); 66 SYSCTL_LONG(_lwkt, OID_AUTO, kq_collisions, 67 CTLFLAG_RW, &kq_token.t_collisions, 0, ""); 68 69 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system"); 70 71 struct kevent_copyin_args { 72 struct kevent_args *ka; 73 int pchanges; 74 }; 75 76 static int kqueue_sleep(struct kqueue *kq, struct timespec *tsp); 77 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count, 78 struct knote *marker); 79 static int kqueue_read(struct file *fp, struct uio *uio, 80 struct ucred *cred, int flags); 81 static int kqueue_write(struct file *fp, struct uio *uio, 82 struct ucred *cred, int flags); 83 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data, 84 struct ucred *cred, struct sysmsg *msg); 85 static int kqueue_kqfilter(struct file *fp, struct knote *kn); 86 static int kqueue_stat(struct file *fp, struct stat *st, 87 struct ucred *cred); 88 static int kqueue_close(struct file *fp); 89 static void kqueue_wakeup(struct kqueue *kq); 90 static int filter_attach(struct knote *kn); 91 static int filter_event(struct knote *kn, long hint); 92 93 /* 94 * MPSAFE 95 */ 96 static struct fileops kqueueops = { 97 .fo_read = kqueue_read, 98 .fo_write = kqueue_write, 99 .fo_ioctl = kqueue_ioctl, 100 .fo_kqfilter = kqueue_kqfilter, 101 .fo_stat = kqueue_stat, 102 .fo_close = kqueue_close, 103 .fo_shutdown = nofo_shutdown 104 }; 105 106 static void knote_attach(struct knote *kn); 107 static void knote_drop(struct knote *kn); 108 static void knote_detach_and_drop(struct knote *kn); 109 static void knote_enqueue(struct knote *kn); 110 static void knote_dequeue(struct knote *kn); 111 static void knote_init(void); 112 static struct knote *knote_alloc(void); 113 static void knote_free(struct knote *kn); 114 115 static void filt_kqdetach(struct knote *kn); 116 static int filt_kqueue(struct knote *kn, long hint); 117 static int filt_procattach(struct knote *kn); 118 static void filt_procdetach(struct knote *kn); 119 static int filt_proc(struct knote *kn, long hint); 120 static int filt_fileattach(struct knote *kn); 121 static void filt_timerexpire(void *knx); 122 static int filt_timerattach(struct knote *kn); 123 static void filt_timerdetach(struct knote *kn); 124 static int filt_timer(struct knote *kn, long hint); 125 126 static struct filterops file_filtops = 127 { FILTEROP_ISFD, filt_fileattach, NULL, NULL }; 128 static struct filterops kqread_filtops = 129 { FILTEROP_ISFD, NULL, filt_kqdetach, filt_kqueue }; 130 static struct filterops proc_filtops = 131 { 0, filt_procattach, filt_procdetach, filt_proc }; 132 static struct filterops timer_filtops = 133 { 0, filt_timerattach, filt_timerdetach, filt_timer }; 134 135 static vm_zone_t knote_zone; 136 static int kq_ncallouts = 0; 137 static int kq_calloutmax = (4 * 1024); 138 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW, 139 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue"); 140 static int kq_checkloop = 1000000; 141 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW, 142 &kq_checkloop, 0, "Maximum number of callouts allocated for kqueue"); 143 144 #define KNOTE_ACTIVATE(kn) do { \ 145 kn->kn_status |= KN_ACTIVE; \ 146 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \ 147 knote_enqueue(kn); \ 148 } while(0) 149 150 #define KN_HASHSIZE 64 /* XXX should be tunable */ 151 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask)) 152 153 extern struct filterops aio_filtops; 154 extern struct filterops sig_filtops; 155 156 /* 157 * Table for for all system-defined filters. 158 */ 159 static struct filterops *sysfilt_ops[] = { 160 &file_filtops, /* EVFILT_READ */ 161 &file_filtops, /* EVFILT_WRITE */ 162 &aio_filtops, /* EVFILT_AIO */ 163 &file_filtops, /* EVFILT_VNODE */ 164 &proc_filtops, /* EVFILT_PROC */ 165 &sig_filtops, /* EVFILT_SIGNAL */ 166 &timer_filtops, /* EVFILT_TIMER */ 167 &file_filtops, /* EVFILT_EXCEPT */ 168 }; 169 170 static int 171 filt_fileattach(struct knote *kn) 172 { 173 return (fo_kqfilter(kn->kn_fp, kn)); 174 } 175 176 /* 177 * MPSAFE 178 */ 179 static int 180 kqueue_kqfilter(struct file *fp, struct knote *kn) 181 { 182 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 183 184 if (kn->kn_filter != EVFILT_READ) 185 return (EOPNOTSUPP); 186 187 kn->kn_fop = &kqread_filtops; 188 knote_insert(&kq->kq_kqinfo.ki_note, kn); 189 return (0); 190 } 191 192 static void 193 filt_kqdetach(struct knote *kn) 194 { 195 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 196 197 knote_remove(&kq->kq_kqinfo.ki_note, kn); 198 } 199 200 /*ARGSUSED*/ 201 static int 202 filt_kqueue(struct knote *kn, long hint) 203 { 204 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 205 206 kn->kn_data = kq->kq_count; 207 return (kn->kn_data > 0); 208 } 209 210 static int 211 filt_procattach(struct knote *kn) 212 { 213 struct proc *p; 214 int immediate; 215 216 immediate = 0; 217 lwkt_gettoken(&proc_token); 218 p = pfind(kn->kn_id); 219 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) { 220 p = zpfind(kn->kn_id); 221 immediate = 1; 222 } 223 if (p == NULL) { 224 lwkt_reltoken(&proc_token); 225 return (ESRCH); 226 } 227 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) { 228 lwkt_reltoken(&proc_token); 229 return (EACCES); 230 } 231 232 kn->kn_ptr.p_proc = p; 233 kn->kn_flags |= EV_CLEAR; /* automatically set */ 234 235 /* 236 * internal flag indicating registration done by kernel 237 */ 238 if (kn->kn_flags & EV_FLAG1) { 239 kn->kn_data = kn->kn_sdata; /* ppid */ 240 kn->kn_fflags = NOTE_CHILD; 241 kn->kn_flags &= ~EV_FLAG1; 242 } 243 244 knote_insert(&p->p_klist, kn); 245 246 /* 247 * Immediately activate any exit notes if the target process is a 248 * zombie. This is necessary to handle the case where the target 249 * process, e.g. a child, dies before the kevent is negistered. 250 */ 251 if (immediate && filt_proc(kn, NOTE_EXIT)) 252 KNOTE_ACTIVATE(kn); 253 lwkt_reltoken(&proc_token); 254 255 return (0); 256 } 257 258 /* 259 * The knote may be attached to a different process, which may exit, 260 * leaving nothing for the knote to be attached to. So when the process 261 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so 262 * it will be deleted when read out. However, as part of the knote deletion, 263 * this routine is called, so a check is needed to avoid actually performing 264 * a detach, because the original process does not exist any more. 265 */ 266 static void 267 filt_procdetach(struct knote *kn) 268 { 269 struct proc *p; 270 271 if (kn->kn_status & KN_DETACHED) 272 return; 273 /* XXX locking? take proc_token here? */ 274 p = kn->kn_ptr.p_proc; 275 knote_remove(&p->p_klist, kn); 276 } 277 278 static int 279 filt_proc(struct knote *kn, long hint) 280 { 281 u_int event; 282 283 /* 284 * mask off extra data 285 */ 286 event = (u_int)hint & NOTE_PCTRLMASK; 287 288 /* 289 * if the user is interested in this event, record it. 290 */ 291 if (kn->kn_sfflags & event) 292 kn->kn_fflags |= event; 293 294 /* 295 * Process is gone, so flag the event as finished. Detach the 296 * knote from the process now because the process will be poof, 297 * gone later on. 298 */ 299 if (event == NOTE_EXIT) { 300 struct proc *p = kn->kn_ptr.p_proc; 301 if ((kn->kn_status & KN_DETACHED) == 0) { 302 knote_remove(&p->p_klist, kn); 303 kn->kn_status |= KN_DETACHED; 304 kn->kn_data = p->p_xstat; 305 kn->kn_ptr.p_proc = NULL; 306 } 307 kn->kn_flags |= (EV_EOF | EV_ONESHOT); 308 return (1); 309 } 310 311 /* 312 * process forked, and user wants to track the new process, 313 * so attach a new knote to it, and immediately report an 314 * event with the parent's pid. 315 */ 316 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) { 317 struct kevent kev; 318 int error; 319 320 /* 321 * register knote with new process. 322 */ 323 kev.ident = hint & NOTE_PDATAMASK; /* pid */ 324 kev.filter = kn->kn_filter; 325 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1; 326 kev.fflags = kn->kn_sfflags; 327 kev.data = kn->kn_id; /* parent */ 328 kev.udata = kn->kn_kevent.udata; /* preserve udata */ 329 error = kqueue_register(kn->kn_kq, &kev); 330 if (error) 331 kn->kn_fflags |= NOTE_TRACKERR; 332 } 333 334 return (kn->kn_fflags != 0); 335 } 336 337 /* 338 * The callout interlocks with callout_stop() (or should), so the 339 * knote should still be a valid structure. However the timeout 340 * can race a deletion so if KN_DELETING is set we just don't touch 341 * the knote. 342 */ 343 static void 344 filt_timerexpire(void *knx) 345 { 346 struct knote *kn = knx; 347 struct callout *calloutp; 348 struct timeval tv; 349 int tticks; 350 351 lwkt_gettoken(&kq_token); 352 if ((kn->kn_status & KN_DELETING) == 0) { 353 kn->kn_data++; 354 KNOTE_ACTIVATE(kn); 355 356 if ((kn->kn_flags & EV_ONESHOT) == 0) { 357 tv.tv_sec = kn->kn_sdata / 1000; 358 tv.tv_usec = (kn->kn_sdata % 1000) * 1000; 359 tticks = tvtohz_high(&tv); 360 calloutp = (struct callout *)kn->kn_hook; 361 callout_reset(calloutp, tticks, filt_timerexpire, kn); 362 } 363 } 364 lwkt_reltoken(&kq_token); 365 } 366 367 /* 368 * data contains amount of time to sleep, in milliseconds 369 */ 370 static int 371 filt_timerattach(struct knote *kn) 372 { 373 struct callout *calloutp; 374 struct timeval tv; 375 int tticks; 376 377 if (kq_ncallouts >= kq_calloutmax) 378 return (ENOMEM); 379 kq_ncallouts++; 380 381 tv.tv_sec = kn->kn_sdata / 1000; 382 tv.tv_usec = (kn->kn_sdata % 1000) * 1000; 383 tticks = tvtohz_high(&tv); 384 385 kn->kn_flags |= EV_CLEAR; /* automatically set */ 386 MALLOC(calloutp, struct callout *, sizeof(*calloutp), 387 M_KQUEUE, M_WAITOK); 388 callout_init(calloutp); 389 kn->kn_hook = (caddr_t)calloutp; 390 callout_reset(calloutp, tticks, filt_timerexpire, kn); 391 392 return (0); 393 } 394 395 static void 396 filt_timerdetach(struct knote *kn) 397 { 398 struct callout *calloutp; 399 400 calloutp = (struct callout *)kn->kn_hook; 401 callout_stop(calloutp); 402 FREE(calloutp, M_KQUEUE); 403 kq_ncallouts--; 404 } 405 406 static int 407 filt_timer(struct knote *kn, long hint) 408 { 409 410 return (kn->kn_data != 0); 411 } 412 413 /* 414 * Acquire a knote, return non-zero on success, 0 on failure. 415 * 416 * If we cannot acquire the knote we sleep and return 0. The knote 417 * may be stale on return in this case and the caller must restart 418 * whatever loop they are in. 419 */ 420 static __inline 421 int 422 knote_acquire(struct knote *kn) 423 { 424 if (kn->kn_status & KN_PROCESSING) { 425 kn->kn_status |= KN_WAITING | KN_REPROCESS; 426 tsleep(kn, 0, "kqepts", hz); 427 /* knote may be stale now */ 428 return(0); 429 } 430 kn->kn_status |= KN_PROCESSING; 431 return(1); 432 } 433 434 /* 435 * Release an acquired knote, clearing KN_PROCESSING and handling any 436 * KN_REPROCESS events. 437 * 438 * Non-zero is returned if the knote is destroyed. 439 */ 440 static __inline 441 int 442 knote_release(struct knote *kn) 443 { 444 while (kn->kn_status & KN_REPROCESS) { 445 kn->kn_status &= ~KN_REPROCESS; 446 if (kn->kn_status & KN_WAITING) { 447 kn->kn_status &= ~KN_WAITING; 448 wakeup(kn); 449 } 450 if (kn->kn_status & KN_DELETING) { 451 knote_detach_and_drop(kn); 452 return(1); 453 /* NOT REACHED */ 454 } 455 if (filter_event(kn, 0)) 456 KNOTE_ACTIVATE(kn); 457 } 458 kn->kn_status &= ~KN_PROCESSING; 459 return(0); 460 } 461 462 /* 463 * Initialize a kqueue. 464 * 465 * NOTE: The lwp/proc code initializes a kqueue for select/poll ops. 466 * 467 * MPSAFE 468 */ 469 void 470 kqueue_init(struct kqueue *kq, struct filedesc *fdp) 471 { 472 TAILQ_INIT(&kq->kq_knpend); 473 TAILQ_INIT(&kq->kq_knlist); 474 kq->kq_count = 0; 475 kq->kq_fdp = fdp; 476 SLIST_INIT(&kq->kq_kqinfo.ki_note); 477 } 478 479 /* 480 * Terminate a kqueue. Freeing the actual kq itself is left up to the 481 * caller (it might be embedded in a lwp so we don't do it here). 482 * 483 * The kq's knlist must be completely eradicated so block on any 484 * processing races. 485 */ 486 void 487 kqueue_terminate(struct kqueue *kq) 488 { 489 struct knote *kn; 490 491 lwkt_gettoken(&kq_token); 492 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL) { 493 if (knote_acquire(kn)) 494 knote_detach_and_drop(kn); 495 } 496 if (kq->kq_knhash) { 497 kfree(kq->kq_knhash, M_KQUEUE); 498 kq->kq_knhash = NULL; 499 kq->kq_knhashmask = 0; 500 } 501 lwkt_reltoken(&kq_token); 502 } 503 504 /* 505 * MPSAFE 506 */ 507 int 508 sys_kqueue(struct kqueue_args *uap) 509 { 510 struct thread *td = curthread; 511 struct kqueue *kq; 512 struct file *fp; 513 int fd, error; 514 515 error = falloc(td->td_lwp, &fp, &fd); 516 if (error) 517 return (error); 518 fp->f_flag = FREAD | FWRITE; 519 fp->f_type = DTYPE_KQUEUE; 520 fp->f_ops = &kqueueops; 521 522 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO); 523 kqueue_init(kq, td->td_proc->p_fd); 524 fp->f_data = kq; 525 526 fsetfd(kq->kq_fdp, fp, fd); 527 uap->sysmsg_result = fd; 528 fdrop(fp); 529 return (error); 530 } 531 532 /* 533 * Copy 'count' items into the destination list pointed to by uap->eventlist. 534 */ 535 static int 536 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res) 537 { 538 struct kevent_copyin_args *kap; 539 int error; 540 541 kap = (struct kevent_copyin_args *)arg; 542 543 error = copyout(kevp, kap->ka->eventlist, count * sizeof(*kevp)); 544 if (error == 0) { 545 kap->ka->eventlist += count; 546 *res += count; 547 } else { 548 *res = -1; 549 } 550 551 return (error); 552 } 553 554 /* 555 * Copy at most 'max' items from the list pointed to by kap->changelist, 556 * return number of items in 'events'. 557 */ 558 static int 559 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events) 560 { 561 struct kevent_copyin_args *kap; 562 int error, count; 563 564 kap = (struct kevent_copyin_args *)arg; 565 566 count = min(kap->ka->nchanges - kap->pchanges, max); 567 error = copyin(kap->ka->changelist, kevp, count * sizeof *kevp); 568 if (error == 0) { 569 kap->ka->changelist += count; 570 kap->pchanges += count; 571 *events = count; 572 } 573 574 return (error); 575 } 576 577 /* 578 * MPSAFE 579 */ 580 int 581 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap, 582 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn, 583 struct timespec *tsp_in) 584 { 585 struct kevent *kevp; 586 struct timespec *tsp; 587 int i, n, total, error, nerrors = 0; 588 int lres; 589 int limit = kq_checkloop; 590 struct kevent kev[KQ_NEVENTS]; 591 struct knote marker; 592 593 tsp = tsp_in; 594 *res = 0; 595 596 lwkt_gettoken(&kq_token); 597 for ( ;; ) { 598 n = 0; 599 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n); 600 if (error) 601 goto done; 602 if (n == 0) 603 break; 604 for (i = 0; i < n; i++) { 605 kevp = &kev[i]; 606 kevp->flags &= ~EV_SYSFLAGS; 607 error = kqueue_register(kq, kevp); 608 609 /* 610 * If a registration returns an error we 611 * immediately post the error. The kevent() 612 * call itself will fail with the error if 613 * no space is available for posting. 614 * 615 * Such errors normally bypass the timeout/blocking 616 * code. However, if the copyoutfn function refuses 617 * to post the error (see sys_poll()), then we 618 * ignore it too. 619 */ 620 if (error) { 621 kevp->flags = EV_ERROR; 622 kevp->data = error; 623 lres = *res; 624 kevent_copyoutfn(uap, kevp, 1, res); 625 if (lres != *res) { 626 nevents--; 627 nerrors++; 628 } 629 } 630 } 631 } 632 if (nerrors) { 633 error = 0; 634 goto done; 635 } 636 637 /* 638 * Acquire/wait for events - setup timeout 639 */ 640 if (tsp != NULL) { 641 struct timespec ats; 642 643 if (tsp->tv_sec || tsp->tv_nsec) { 644 nanouptime(&ats); 645 timespecadd(tsp, &ats); /* tsp = target time */ 646 } 647 } 648 649 /* 650 * Loop as required. 651 * 652 * Collect as many events as we can. Sleeping on successive 653 * loops is disabled if copyoutfn has incremented (*res). 654 * 655 * The loop stops if an error occurs, all events have been 656 * scanned (the marker has been reached), or fewer than the 657 * maximum number of events is found. 658 * 659 * The copyoutfn function does not have to increment (*res) in 660 * order for the loop to continue. 661 * 662 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents. 663 */ 664 total = 0; 665 error = 0; 666 marker.kn_filter = EVFILT_MARKER; 667 marker.kn_status = KN_PROCESSING; 668 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 669 while ((n = nevents - total) > 0) { 670 if (n > KQ_NEVENTS) 671 n = KQ_NEVENTS; 672 673 /* 674 * If no events are pending sleep until timeout (if any) 675 * or an event occurs. 676 * 677 * After the sleep completes the marker is moved to the 678 * end of the list, making any received events available 679 * to our scan. 680 */ 681 if (kq->kq_count == 0 && *res == 0) { 682 error = kqueue_sleep(kq, tsp); 683 if (error) 684 break; 685 686 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 687 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 688 } 689 690 /* 691 * Process all received events 692 * Account for all non-spurious events in our total 693 */ 694 i = kqueue_scan(kq, kev, n, &marker); 695 if (i) { 696 lres = *res; 697 error = kevent_copyoutfn(uap, kev, i, res); 698 total += *res - lres; 699 if (error) 700 break; 701 } 702 if (limit && --limit == 0) 703 panic("kqueue: checkloop failed i=%d", i); 704 705 /* 706 * Normally when fewer events are returned than requested 707 * we can stop. However, if only spurious events were 708 * collected the copyout will not bump (*res) and we have 709 * to continue. 710 */ 711 if (i < n && *res) 712 break; 713 714 /* 715 * Deal with an edge case where spurious events can cause 716 * a loop to occur without moving the marker. This can 717 * prevent kqueue_scan() from picking up new events which 718 * race us. We must be sure to move the marker for this 719 * case. 720 * 721 * NOTE: We do not want to move the marker if events 722 * were scanned because normal kqueue operations 723 * may reactivate events. Moving the marker in 724 * that case could result in duplicates for the 725 * same event. 726 */ 727 if (i == 0) { 728 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 729 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 730 } 731 } 732 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 733 734 /* Timeouts do not return EWOULDBLOCK. */ 735 if (error == EWOULDBLOCK) 736 error = 0; 737 738 done: 739 lwkt_reltoken(&kq_token); 740 return (error); 741 } 742 743 /* 744 * MPALMOSTSAFE 745 */ 746 int 747 sys_kevent(struct kevent_args *uap) 748 { 749 struct thread *td = curthread; 750 struct proc *p = td->td_proc; 751 struct timespec ts, *tsp; 752 struct kqueue *kq; 753 struct file *fp = NULL; 754 struct kevent_copyin_args *kap, ka; 755 int error; 756 757 if (uap->timeout) { 758 error = copyin(uap->timeout, &ts, sizeof(ts)); 759 if (error) 760 return (error); 761 tsp = &ts; 762 } else { 763 tsp = NULL; 764 } 765 766 fp = holdfp(p->p_fd, uap->fd, -1); 767 if (fp == NULL) 768 return (EBADF); 769 if (fp->f_type != DTYPE_KQUEUE) { 770 fdrop(fp); 771 return (EBADF); 772 } 773 774 kq = (struct kqueue *)fp->f_data; 775 776 kap = &ka; 777 kap->ka = uap; 778 kap->pchanges = 0; 779 780 error = kern_kevent(kq, uap->nevents, &uap->sysmsg_result, kap, 781 kevent_copyin, kevent_copyout, tsp); 782 783 fdrop(fp); 784 785 return (error); 786 } 787 788 int 789 kqueue_register(struct kqueue *kq, struct kevent *kev) 790 { 791 struct filedesc *fdp = kq->kq_fdp; 792 struct filterops *fops; 793 struct file *fp = NULL; 794 struct knote *kn = NULL; 795 int error = 0; 796 797 if (kev->filter < 0) { 798 if (kev->filter + EVFILT_SYSCOUNT < 0) 799 return (EINVAL); 800 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */ 801 } else { 802 /* 803 * XXX 804 * filter attach routine is responsible for insuring that 805 * the identifier can be attached to it. 806 */ 807 kprintf("unknown filter: %d\n", kev->filter); 808 return (EINVAL); 809 } 810 811 lwkt_gettoken(&kq_token); 812 if (fops->f_flags & FILTEROP_ISFD) { 813 /* validate descriptor */ 814 fp = holdfp(fdp, kev->ident, -1); 815 if (fp == NULL) { 816 lwkt_reltoken(&kq_token); 817 return (EBADF); 818 } 819 820 again1: 821 SLIST_FOREACH(kn, &fp->f_klist, kn_link) { 822 if (kn->kn_kq == kq && 823 kn->kn_filter == kev->filter && 824 kn->kn_id == kev->ident) { 825 if (knote_acquire(kn) == 0) 826 goto again1; 827 break; 828 } 829 } 830 } else { 831 if (kq->kq_knhashmask) { 832 struct klist *list; 833 834 list = &kq->kq_knhash[ 835 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)]; 836 again2: 837 SLIST_FOREACH(kn, list, kn_link) { 838 if (kn->kn_id == kev->ident && 839 kn->kn_filter == kev->filter) { 840 if (knote_acquire(kn) == 0) 841 goto again2; 842 break; 843 } 844 } 845 } 846 } 847 848 /* 849 * NOTE: At this point if kn is non-NULL we will have acquired 850 * it and set KN_PROCESSING. 851 */ 852 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) { 853 error = ENOENT; 854 goto done; 855 } 856 857 /* 858 * kn now contains the matching knote, or NULL if no match 859 */ 860 if (kev->flags & EV_ADD) { 861 if (kn == NULL) { 862 kn = knote_alloc(); 863 if (kn == NULL) { 864 error = ENOMEM; 865 goto done; 866 } 867 kn->kn_fp = fp; 868 kn->kn_kq = kq; 869 kn->kn_fop = fops; 870 871 /* 872 * apply reference count to knote structure, and 873 * do not release it at the end of this routine. 874 */ 875 fp = NULL; 876 877 kn->kn_sfflags = kev->fflags; 878 kn->kn_sdata = kev->data; 879 kev->fflags = 0; 880 kev->data = 0; 881 kn->kn_kevent = *kev; 882 883 /* 884 * KN_PROCESSING prevents the knote from getting 885 * ripped out from under us while we are trying 886 * to attach it, in case the attach blocks. 887 */ 888 kn->kn_status = KN_PROCESSING; 889 knote_attach(kn); 890 if ((error = filter_attach(kn)) != 0) { 891 kn->kn_status |= KN_DELETING | KN_REPROCESS; 892 knote_drop(kn); 893 goto done; 894 } 895 896 /* 897 * Interlock against close races which either tried 898 * to remove our knote while we were blocked or missed 899 * it entirely prior to our attachment. We do not 900 * want to end up with a knote on a closed descriptor. 901 */ 902 if ((fops->f_flags & FILTEROP_ISFD) && 903 checkfdclosed(fdp, kev->ident, kn->kn_fp)) { 904 kn->kn_status |= KN_DELETING | KN_REPROCESS; 905 } 906 } else { 907 /* 908 * The user may change some filter values after the 909 * initial EV_ADD, but doing so will not reset any 910 * filter which have already been triggered. 911 */ 912 KKASSERT(kn->kn_status & KN_PROCESSING); 913 kn->kn_sfflags = kev->fflags; 914 kn->kn_sdata = kev->data; 915 kn->kn_kevent.udata = kev->udata; 916 } 917 918 /* 919 * Execute the filter event to immediately activate the 920 * knote if necessary. If reprocessing events are pending 921 * due to blocking above we do not run the filter here 922 * but instead let knote_release() do it. Otherwise we 923 * might run the filter on a deleted event. 924 */ 925 if ((kn->kn_status & KN_REPROCESS) == 0) { 926 if (filter_event(kn, 0)) 927 KNOTE_ACTIVATE(kn); 928 } 929 } else if (kev->flags & EV_DELETE) { 930 /* 931 * Delete the existing knote 932 */ 933 knote_detach_and_drop(kn); 934 goto done; 935 } 936 937 /* 938 * Disablement does not deactivate a knote here. 939 */ 940 if ((kev->flags & EV_DISABLE) && 941 ((kn->kn_status & KN_DISABLED) == 0)) { 942 kn->kn_status |= KN_DISABLED; 943 } 944 945 /* 946 * Re-enablement may have to immediately enqueue an active knote. 947 */ 948 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) { 949 kn->kn_status &= ~KN_DISABLED; 950 if ((kn->kn_status & KN_ACTIVE) && 951 ((kn->kn_status & KN_QUEUED) == 0)) { 952 knote_enqueue(kn); 953 } 954 } 955 956 /* 957 * Handle any required reprocessing 958 */ 959 knote_release(kn); 960 /* kn may be invalid now */ 961 962 done: 963 lwkt_reltoken(&kq_token); 964 if (fp != NULL) 965 fdrop(fp); 966 return (error); 967 } 968 969 /* 970 * Block as necessary until the target time is reached. 971 * If tsp is NULL we block indefinitely. If tsp->ts_secs/nsecs are both 972 * 0 we do not block at all. 973 */ 974 static int 975 kqueue_sleep(struct kqueue *kq, struct timespec *tsp) 976 { 977 int error = 0; 978 979 if (tsp == NULL) { 980 kq->kq_state |= KQ_SLEEP; 981 error = tsleep(kq, PCATCH, "kqread", 0); 982 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) { 983 error = EWOULDBLOCK; 984 } else { 985 struct timespec ats; 986 struct timespec atx = *tsp; 987 int timeout; 988 989 nanouptime(&ats); 990 timespecsub(&atx, &ats); 991 if (ats.tv_sec < 0) { 992 error = EWOULDBLOCK; 993 } else { 994 timeout = atx.tv_sec > 24 * 60 * 60 ? 995 24 * 60 * 60 * hz : tstohz_high(&atx); 996 kq->kq_state |= KQ_SLEEP; 997 error = tsleep(kq, PCATCH, "kqread", timeout); 998 } 999 } 1000 1001 /* don't restart after signals... */ 1002 if (error == ERESTART) 1003 return (EINTR); 1004 1005 return (error); 1006 } 1007 1008 /* 1009 * Scan the kqueue, return the number of active events placed in kevp up 1010 * to count. 1011 * 1012 * Continuous mode events may get recycled, do not continue scanning past 1013 * marker unless no events have been collected. 1014 */ 1015 static int 1016 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count, 1017 struct knote *marker) 1018 { 1019 struct knote *kn, local_marker; 1020 int total; 1021 1022 total = 0; 1023 local_marker.kn_filter = EVFILT_MARKER; 1024 local_marker.kn_status = KN_PROCESSING; 1025 1026 /* 1027 * Collect events. 1028 */ 1029 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe); 1030 while (count) { 1031 kn = TAILQ_NEXT(&local_marker, kn_tqe); 1032 if (kn->kn_filter == EVFILT_MARKER) { 1033 /* Marker reached, we are done */ 1034 if (kn == marker) 1035 break; 1036 1037 /* Move local marker past some other threads marker */ 1038 kn = TAILQ_NEXT(kn, kn_tqe); 1039 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe); 1040 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe); 1041 continue; 1042 } 1043 1044 /* 1045 * We can't skip a knote undergoing processing, otherwise 1046 * we risk not returning it when the user process expects 1047 * it should be returned. Sleep and retry. 1048 */ 1049 if (knote_acquire(kn) == 0) 1050 continue; 1051 1052 /* 1053 * Remove the event for processing. 1054 * 1055 * WARNING! We must leave KN_QUEUED set to prevent the 1056 * event from being KNOTE_ACTIVATE()d while 1057 * the queue state is in limbo, in case we 1058 * block. 1059 * 1060 * WARNING! We must set KN_PROCESSING to avoid races 1061 * against deletion or another thread's 1062 * processing. 1063 */ 1064 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe); 1065 kq->kq_count--; 1066 1067 /* 1068 * We have to deal with an extremely important race against 1069 * file descriptor close()s here. The file descriptor can 1070 * disappear MPSAFE, and there is a small window of 1071 * opportunity between that and the call to knote_fdclose(). 1072 * 1073 * If we hit that window here while doselect or dopoll is 1074 * trying to delete a spurious event they will not be able 1075 * to match up the event against a knote and will go haywire. 1076 */ 1077 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) && 1078 checkfdclosed(kq->kq_fdp, kn->kn_kevent.ident, kn->kn_fp)) { 1079 kn->kn_status |= KN_DELETING | KN_REPROCESS; 1080 } 1081 1082 if (kn->kn_status & KN_DISABLED) { 1083 /* 1084 * If disabled we ensure the event is not queued 1085 * but leave its active bit set. On re-enablement 1086 * the event may be immediately triggered. 1087 */ 1088 kn->kn_status &= ~KN_QUEUED; 1089 } else if ((kn->kn_flags & EV_ONESHOT) == 0 && 1090 (kn->kn_status & KN_DELETING) == 0 && 1091 filter_event(kn, 0) == 0) { 1092 /* 1093 * If not running in one-shot mode and the event 1094 * is no longer present we ensure it is removed 1095 * from the queue and ignore it. 1096 */ 1097 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE); 1098 } else { 1099 /* 1100 * Post the event 1101 */ 1102 *kevp++ = kn->kn_kevent; 1103 ++total; 1104 --count; 1105 1106 if (kn->kn_flags & EV_ONESHOT) { 1107 kn->kn_status &= ~KN_QUEUED; 1108 kn->kn_status |= KN_DELETING | KN_REPROCESS; 1109 } else if (kn->kn_flags & EV_CLEAR) { 1110 kn->kn_data = 0; 1111 kn->kn_fflags = 0; 1112 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE); 1113 } else { 1114 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe); 1115 kq->kq_count++; 1116 } 1117 } 1118 1119 /* 1120 * Handle any post-processing states 1121 */ 1122 knote_release(kn); 1123 } 1124 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe); 1125 1126 return (total); 1127 } 1128 1129 /* 1130 * XXX 1131 * This could be expanded to call kqueue_scan, if desired. 1132 * 1133 * MPSAFE 1134 */ 1135 static int 1136 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags) 1137 { 1138 return (ENXIO); 1139 } 1140 1141 /* 1142 * MPSAFE 1143 */ 1144 static int 1145 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags) 1146 { 1147 return (ENXIO); 1148 } 1149 1150 /* 1151 * MPALMOSTSAFE 1152 */ 1153 static int 1154 kqueue_ioctl(struct file *fp, u_long com, caddr_t data, 1155 struct ucred *cred, struct sysmsg *msg) 1156 { 1157 struct kqueue *kq; 1158 int error; 1159 1160 lwkt_gettoken(&kq_token); 1161 kq = (struct kqueue *)fp->f_data; 1162 1163 switch(com) { 1164 case FIOASYNC: 1165 if (*(int *)data) 1166 kq->kq_state |= KQ_ASYNC; 1167 else 1168 kq->kq_state &= ~KQ_ASYNC; 1169 error = 0; 1170 break; 1171 case FIOSETOWN: 1172 error = fsetown(*(int *)data, &kq->kq_sigio); 1173 break; 1174 default: 1175 error = ENOTTY; 1176 break; 1177 } 1178 lwkt_reltoken(&kq_token); 1179 return (error); 1180 } 1181 1182 /* 1183 * MPSAFE 1184 */ 1185 static int 1186 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred) 1187 { 1188 struct kqueue *kq = (struct kqueue *)fp->f_data; 1189 1190 bzero((void *)st, sizeof(*st)); 1191 st->st_size = kq->kq_count; 1192 st->st_blksize = sizeof(struct kevent); 1193 st->st_mode = S_IFIFO; 1194 return (0); 1195 } 1196 1197 /* 1198 * MPSAFE 1199 */ 1200 static int 1201 kqueue_close(struct file *fp) 1202 { 1203 struct kqueue *kq = (struct kqueue *)fp->f_data; 1204 1205 kqueue_terminate(kq); 1206 1207 fp->f_data = NULL; 1208 funsetown(kq->kq_sigio); 1209 1210 kfree(kq, M_KQUEUE); 1211 return (0); 1212 } 1213 1214 static void 1215 kqueue_wakeup(struct kqueue *kq) 1216 { 1217 if (kq->kq_state & KQ_SLEEP) { 1218 kq->kq_state &= ~KQ_SLEEP; 1219 wakeup(kq); 1220 } 1221 KNOTE(&kq->kq_kqinfo.ki_note, 0); 1222 } 1223 1224 /* 1225 * Calls filterops f_attach function, acquiring mplock if filter is not 1226 * marked as FILTEROP_MPSAFE. 1227 */ 1228 static int 1229 filter_attach(struct knote *kn) 1230 { 1231 int ret; 1232 1233 if (!(kn->kn_fop->f_flags & FILTEROP_MPSAFE)) { 1234 get_mplock(); 1235 ret = kn->kn_fop->f_attach(kn); 1236 rel_mplock(); 1237 } else { 1238 ret = kn->kn_fop->f_attach(kn); 1239 } 1240 1241 return (ret); 1242 } 1243 1244 /* 1245 * Detach the knote and drop it, destroying the knote. 1246 * 1247 * Calls filterops f_detach function, acquiring mplock if filter is not 1248 * marked as FILTEROP_MPSAFE. 1249 */ 1250 static void 1251 knote_detach_and_drop(struct knote *kn) 1252 { 1253 kn->kn_status |= KN_DELETING | KN_REPROCESS; 1254 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) { 1255 kn->kn_fop->f_detach(kn); 1256 } else { 1257 get_mplock(); 1258 kn->kn_fop->f_detach(kn); 1259 rel_mplock(); 1260 } 1261 knote_drop(kn); 1262 } 1263 1264 /* 1265 * Calls filterops f_event function, acquiring mplock if filter is not 1266 * marked as FILTEROP_MPSAFE. 1267 * 1268 * If the knote is in the middle of being created or deleted we cannot 1269 * safely call the filter op. 1270 */ 1271 static int 1272 filter_event(struct knote *kn, long hint) 1273 { 1274 int ret; 1275 1276 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) { 1277 ret = kn->kn_fop->f_event(kn, hint); 1278 } else { 1279 get_mplock(); 1280 ret = kn->kn_fop->f_event(kn, hint); 1281 rel_mplock(); 1282 } 1283 return (ret); 1284 } 1285 1286 /* 1287 * Walk down a list of knotes, activating them if their event has triggered. 1288 * 1289 * If we encounter any knotes which are undergoing processing we just mark 1290 * them for reprocessing and do not try to [re]activate the knote. However, 1291 * if a hint is being passed we have to wait and that makes things a bit 1292 * sticky. 1293 */ 1294 void 1295 knote(struct klist *list, long hint) 1296 { 1297 struct knote *kn; 1298 1299 lwkt_gettoken(&kq_token); 1300 restart: 1301 SLIST_FOREACH(kn, list, kn_next) { 1302 if (kn->kn_status & KN_PROCESSING) { 1303 /* 1304 * Someone else is processing the knote, ask the 1305 * other thread to reprocess it and don't mess 1306 * with it otherwise. 1307 */ 1308 if (hint == 0) { 1309 kn->kn_status |= KN_REPROCESS; 1310 continue; 1311 } 1312 1313 /* 1314 * If the hint is non-zero we have to wait or risk 1315 * losing the state the caller is trying to update. 1316 * 1317 * XXX This is a real problem, certain process 1318 * and signal filters will bump kn_data for 1319 * already-processed notes more than once if 1320 * we restart the list scan. FIXME. 1321 */ 1322 kn->kn_status |= KN_WAITING | KN_REPROCESS; 1323 tsleep(kn, 0, "knotec", hz); 1324 goto restart; 1325 } 1326 1327 /* 1328 * Become the reprocessing master ourselves. 1329 * 1330 * If hint is non-zer running the event is mandatory 1331 * when not deleting so do it whether reprocessing is 1332 * set or not. 1333 */ 1334 kn->kn_status |= KN_PROCESSING; 1335 if ((kn->kn_status & KN_DELETING) == 0) { 1336 if (filter_event(kn, hint)) 1337 KNOTE_ACTIVATE(kn); 1338 } 1339 if (knote_release(kn)) 1340 goto restart; 1341 } 1342 lwkt_reltoken(&kq_token); 1343 } 1344 1345 /* 1346 * Insert knote at head of klist. 1347 * 1348 * This function may only be called via a filter function and thus 1349 * kq_token should already be held and marked for processing. 1350 */ 1351 void 1352 knote_insert(struct klist *klist, struct knote *kn) 1353 { 1354 KKASSERT(kn->kn_status & KN_PROCESSING); 1355 ASSERT_LWKT_TOKEN_HELD(&kq_token); 1356 SLIST_INSERT_HEAD(klist, kn, kn_next); 1357 } 1358 1359 /* 1360 * Remove knote from a klist 1361 * 1362 * This function may only be called via a filter function and thus 1363 * kq_token should already be held and marked for processing. 1364 */ 1365 void 1366 knote_remove(struct klist *klist, struct knote *kn) 1367 { 1368 KKASSERT(kn->kn_status & KN_PROCESSING); 1369 ASSERT_LWKT_TOKEN_HELD(&kq_token); 1370 SLIST_REMOVE(klist, kn, knote, kn_next); 1371 } 1372 1373 /* 1374 * Remove all knotes from a specified klist 1375 * 1376 * Only called from aio. 1377 */ 1378 void 1379 knote_empty(struct klist *list) 1380 { 1381 struct knote *kn; 1382 1383 lwkt_gettoken(&kq_token); 1384 while ((kn = SLIST_FIRST(list)) != NULL) { 1385 if (knote_acquire(kn)) 1386 knote_detach_and_drop(kn); 1387 } 1388 lwkt_reltoken(&kq_token); 1389 } 1390 1391 void 1392 knote_assume_knotes(struct kqinfo *src, struct kqinfo *dst, 1393 struct filterops *ops, void *hook) 1394 { 1395 struct knote *kn; 1396 1397 lwkt_gettoken(&kq_token); 1398 while ((kn = SLIST_FIRST(&src->ki_note)) != NULL) { 1399 if (knote_acquire(kn)) { 1400 knote_remove(&src->ki_note, kn); 1401 kn->kn_fop = ops; 1402 kn->kn_hook = hook; 1403 knote_insert(&dst->ki_note, kn); 1404 knote_release(kn); 1405 /* kn may be invalid now */ 1406 } 1407 } 1408 lwkt_reltoken(&kq_token); 1409 } 1410 1411 /* 1412 * Remove all knotes referencing a specified fd 1413 */ 1414 void 1415 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd) 1416 { 1417 struct knote *kn; 1418 1419 lwkt_gettoken(&kq_token); 1420 restart: 1421 SLIST_FOREACH(kn, &fp->f_klist, kn_link) { 1422 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) { 1423 if (knote_acquire(kn)) 1424 knote_detach_and_drop(kn); 1425 goto restart; 1426 } 1427 } 1428 lwkt_reltoken(&kq_token); 1429 } 1430 1431 /* 1432 * Low level attach function. 1433 * 1434 * The knote should already be marked for processing. 1435 */ 1436 static void 1437 knote_attach(struct knote *kn) 1438 { 1439 struct klist *list; 1440 struct kqueue *kq = kn->kn_kq; 1441 1442 if (kn->kn_fop->f_flags & FILTEROP_ISFD) { 1443 KKASSERT(kn->kn_fp); 1444 list = &kn->kn_fp->f_klist; 1445 } else { 1446 if (kq->kq_knhashmask == 0) 1447 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE, 1448 &kq->kq_knhashmask); 1449 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)]; 1450 } 1451 SLIST_INSERT_HEAD(list, kn, kn_link); 1452 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink); 1453 } 1454 1455 /* 1456 * Low level drop function. 1457 * 1458 * The knote should already be marked for processing. 1459 */ 1460 static void 1461 knote_drop(struct knote *kn) 1462 { 1463 struct kqueue *kq; 1464 struct klist *list; 1465 1466 kq = kn->kn_kq; 1467 1468 if (kn->kn_fop->f_flags & FILTEROP_ISFD) 1469 list = &kn->kn_fp->f_klist; 1470 else 1471 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)]; 1472 1473 SLIST_REMOVE(list, kn, knote, kn_link); 1474 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink); 1475 if (kn->kn_status & KN_QUEUED) 1476 knote_dequeue(kn); 1477 if (kn->kn_fop->f_flags & FILTEROP_ISFD) { 1478 fdrop(kn->kn_fp); 1479 kn->kn_fp = NULL; 1480 } 1481 knote_free(kn); 1482 } 1483 1484 /* 1485 * Low level enqueue function. 1486 * 1487 * The knote should already be marked for processing. 1488 */ 1489 static void 1490 knote_enqueue(struct knote *kn) 1491 { 1492 struct kqueue *kq = kn->kn_kq; 1493 1494 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued")); 1495 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe); 1496 kn->kn_status |= KN_QUEUED; 1497 ++kq->kq_count; 1498 1499 /* 1500 * Send SIGIO on request (typically set up as a mailbox signal) 1501 */ 1502 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1) 1503 pgsigio(kq->kq_sigio, SIGIO, 0); 1504 1505 kqueue_wakeup(kq); 1506 } 1507 1508 /* 1509 * Low level dequeue function. 1510 * 1511 * The knote should already be marked for processing. 1512 */ 1513 static void 1514 knote_dequeue(struct knote *kn) 1515 { 1516 struct kqueue *kq = kn->kn_kq; 1517 1518 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued")); 1519 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe); 1520 kn->kn_status &= ~KN_QUEUED; 1521 kq->kq_count--; 1522 } 1523 1524 static void 1525 knote_init(void) 1526 { 1527 knote_zone = zinit("KNOTE", sizeof(struct knote), 0, 0, 1); 1528 } 1529 SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL) 1530 1531 static struct knote * 1532 knote_alloc(void) 1533 { 1534 return ((struct knote *)zalloc(knote_zone)); 1535 } 1536 1537 static void 1538 knote_free(struct knote *kn) 1539 { 1540 zfree(knote_zone, kn); 1541 } 1542