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; 64 65 MALLOC_DEFINE(M_KQUEUE, "kqueue", "memory for kqueue system"); 66 67 struct kevent_copyin_args { 68 struct kevent_args *ka; 69 int pchanges; 70 }; 71 72 static int kqueue_sleep(struct kqueue *kq, struct timespec *tsp); 73 static int kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count, 74 struct knote *marker); 75 static int kqueue_read(struct file *fp, struct uio *uio, 76 struct ucred *cred, int flags); 77 static int kqueue_write(struct file *fp, struct uio *uio, 78 struct ucred *cred, int flags); 79 static int kqueue_ioctl(struct file *fp, u_long com, caddr_t data, 80 struct ucred *cred, struct sysmsg *msg); 81 static int kqueue_kqfilter(struct file *fp, struct knote *kn); 82 static int kqueue_stat(struct file *fp, struct stat *st, 83 struct ucred *cred); 84 static int kqueue_close(struct file *fp); 85 static void kqueue_wakeup(struct kqueue *kq); 86 static int filter_attach(struct knote *kn); 87 static int filter_event(struct knote *kn, long hint); 88 89 /* 90 * MPSAFE 91 */ 92 static struct fileops kqueueops = { 93 .fo_read = kqueue_read, 94 .fo_write = kqueue_write, 95 .fo_ioctl = kqueue_ioctl, 96 .fo_kqfilter = kqueue_kqfilter, 97 .fo_stat = kqueue_stat, 98 .fo_close = kqueue_close, 99 .fo_shutdown = nofo_shutdown 100 }; 101 102 static void knote_attach(struct knote *kn); 103 static void knote_drop(struct knote *kn); 104 static void knote_detach_and_drop(struct knote *kn); 105 static void knote_enqueue(struct knote *kn); 106 static void knote_dequeue(struct knote *kn); 107 static void knote_init(void); 108 static struct knote *knote_alloc(void); 109 static void knote_free(struct knote *kn); 110 111 static void filt_kqdetach(struct knote *kn); 112 static int filt_kqueue(struct knote *kn, long hint); 113 static int filt_procattach(struct knote *kn); 114 static void filt_procdetach(struct knote *kn); 115 static int filt_proc(struct knote *kn, long hint); 116 static int filt_fileattach(struct knote *kn); 117 static void filt_timerexpire(void *knx); 118 static int filt_timerattach(struct knote *kn); 119 static void filt_timerdetach(struct knote *kn); 120 static int filt_timer(struct knote *kn, long hint); 121 122 static struct filterops file_filtops = 123 { FILTEROP_ISFD, filt_fileattach, NULL, NULL }; 124 static struct filterops kqread_filtops = 125 { FILTEROP_ISFD, NULL, filt_kqdetach, filt_kqueue }; 126 static struct filterops proc_filtops = 127 { 0, filt_procattach, filt_procdetach, filt_proc }; 128 static struct filterops timer_filtops = 129 { 0, filt_timerattach, filt_timerdetach, filt_timer }; 130 131 static vm_zone_t knote_zone; 132 static int kq_ncallouts = 0; 133 static int kq_calloutmax = (4 * 1024); 134 SYSCTL_INT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW, 135 &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue"); 136 static int kq_checkloop = 1000000; 137 SYSCTL_INT(_kern, OID_AUTO, kq_checkloop, CTLFLAG_RW, 138 &kq_checkloop, 0, "Maximum number of callouts allocated for kqueue"); 139 140 #define KNOTE_ACTIVATE(kn) do { \ 141 kn->kn_status |= KN_ACTIVE; \ 142 if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) \ 143 knote_enqueue(kn); \ 144 } while(0) 145 146 #define KN_HASHSIZE 64 /* XXX should be tunable */ 147 #define KN_HASH(val, mask) (((val) ^ (val >> 8)) & (mask)) 148 149 extern struct filterops aio_filtops; 150 extern struct filterops sig_filtops; 151 152 /* 153 * Table for for all system-defined filters. 154 */ 155 static struct filterops *sysfilt_ops[] = { 156 &file_filtops, /* EVFILT_READ */ 157 &file_filtops, /* EVFILT_WRITE */ 158 &aio_filtops, /* EVFILT_AIO */ 159 &file_filtops, /* EVFILT_VNODE */ 160 &proc_filtops, /* EVFILT_PROC */ 161 &sig_filtops, /* EVFILT_SIGNAL */ 162 &timer_filtops, /* EVFILT_TIMER */ 163 &file_filtops, /* EVFILT_EXCEPT */ 164 }; 165 166 static int 167 filt_fileattach(struct knote *kn) 168 { 169 return (fo_kqfilter(kn->kn_fp, kn)); 170 } 171 172 /* 173 * MPSAFE 174 */ 175 static int 176 kqueue_kqfilter(struct file *fp, struct knote *kn) 177 { 178 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 179 180 if (kn->kn_filter != EVFILT_READ) 181 return (EOPNOTSUPP); 182 183 kn->kn_fop = &kqread_filtops; 184 knote_insert(&kq->kq_kqinfo.ki_note, kn); 185 return (0); 186 } 187 188 static void 189 filt_kqdetach(struct knote *kn) 190 { 191 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 192 193 knote_remove(&kq->kq_kqinfo.ki_note, kn); 194 } 195 196 /*ARGSUSED*/ 197 static int 198 filt_kqueue(struct knote *kn, long hint) 199 { 200 struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data; 201 202 kn->kn_data = kq->kq_count; 203 return (kn->kn_data > 0); 204 } 205 206 static int 207 filt_procattach(struct knote *kn) 208 { 209 struct proc *p; 210 int immediate; 211 212 immediate = 0; 213 lwkt_gettoken(&proc_token); 214 p = pfind(kn->kn_id); 215 if (p == NULL && (kn->kn_sfflags & NOTE_EXIT)) { 216 p = zpfind(kn->kn_id); 217 immediate = 1; 218 } 219 if (p == NULL) { 220 lwkt_reltoken(&proc_token); 221 return (ESRCH); 222 } 223 if (!PRISON_CHECK(curthread->td_ucred, p->p_ucred)) { 224 lwkt_reltoken(&proc_token); 225 return (EACCES); 226 } 227 228 kn->kn_ptr.p_proc = p; 229 kn->kn_flags |= EV_CLEAR; /* automatically set */ 230 231 /* 232 * internal flag indicating registration done by kernel 233 */ 234 if (kn->kn_flags & EV_FLAG1) { 235 kn->kn_data = kn->kn_sdata; /* ppid */ 236 kn->kn_fflags = NOTE_CHILD; 237 kn->kn_flags &= ~EV_FLAG1; 238 } 239 240 knote_insert(&p->p_klist, kn); 241 242 /* 243 * Immediately activate any exit notes if the target process is a 244 * zombie. This is necessary to handle the case where the target 245 * process, e.g. a child, dies before the kevent is negistered. 246 */ 247 if (immediate && filt_proc(kn, NOTE_EXIT)) 248 KNOTE_ACTIVATE(kn); 249 lwkt_reltoken(&proc_token); 250 251 return (0); 252 } 253 254 /* 255 * The knote may be attached to a different process, which may exit, 256 * leaving nothing for the knote to be attached to. So when the process 257 * exits, the knote is marked as DETACHED and also flagged as ONESHOT so 258 * it will be deleted when read out. However, as part of the knote deletion, 259 * this routine is called, so a check is needed to avoid actually performing 260 * a detach, because the original process does not exist any more. 261 */ 262 static void 263 filt_procdetach(struct knote *kn) 264 { 265 struct proc *p; 266 267 if (kn->kn_status & KN_DETACHED) 268 return; 269 /* XXX locking? take proc_token here? */ 270 p = kn->kn_ptr.p_proc; 271 knote_remove(&p->p_klist, kn); 272 } 273 274 static int 275 filt_proc(struct knote *kn, long hint) 276 { 277 u_int event; 278 279 /* 280 * mask off extra data 281 */ 282 event = (u_int)hint & NOTE_PCTRLMASK; 283 284 /* 285 * if the user is interested in this event, record it. 286 */ 287 if (kn->kn_sfflags & event) 288 kn->kn_fflags |= event; 289 290 /* 291 * Process is gone, so flag the event as finished. Detach the 292 * knote from the process now because the process will be poof, 293 * gone later on. 294 */ 295 if (event == NOTE_EXIT) { 296 struct proc *p = kn->kn_ptr.p_proc; 297 if ((kn->kn_status & KN_DETACHED) == 0) { 298 knote_remove(&p->p_klist, kn); 299 kn->kn_status |= KN_DETACHED; 300 kn->kn_data = p->p_xstat; 301 kn->kn_ptr.p_proc = NULL; 302 } 303 kn->kn_flags |= (EV_EOF | EV_ONESHOT); 304 return (1); 305 } 306 307 /* 308 * process forked, and user wants to track the new process, 309 * so attach a new knote to it, and immediately report an 310 * event with the parent's pid. 311 */ 312 if ((event == NOTE_FORK) && (kn->kn_sfflags & NOTE_TRACK)) { 313 struct kevent kev; 314 int error; 315 316 /* 317 * register knote with new process. 318 */ 319 kev.ident = hint & NOTE_PDATAMASK; /* pid */ 320 kev.filter = kn->kn_filter; 321 kev.flags = kn->kn_flags | EV_ADD | EV_ENABLE | EV_FLAG1; 322 kev.fflags = kn->kn_sfflags; 323 kev.data = kn->kn_id; /* parent */ 324 kev.udata = kn->kn_kevent.udata; /* preserve udata */ 325 error = kqueue_register(kn->kn_kq, &kev); 326 if (error) 327 kn->kn_fflags |= NOTE_TRACKERR; 328 } 329 330 return (kn->kn_fflags != 0); 331 } 332 333 static void 334 filt_timerexpire(void *knx) 335 { 336 struct knote *kn = knx; 337 struct callout *calloutp; 338 struct timeval tv; 339 int tticks; 340 341 kn->kn_data++; 342 KNOTE_ACTIVATE(kn); 343 344 if ((kn->kn_flags & EV_ONESHOT) == 0) { 345 tv.tv_sec = kn->kn_sdata / 1000; 346 tv.tv_usec = (kn->kn_sdata % 1000) * 1000; 347 tticks = tvtohz_high(&tv); 348 calloutp = (struct callout *)kn->kn_hook; 349 callout_reset(calloutp, tticks, filt_timerexpire, kn); 350 } 351 } 352 353 /* 354 * data contains amount of time to sleep, in milliseconds 355 */ 356 static int 357 filt_timerattach(struct knote *kn) 358 { 359 struct callout *calloutp; 360 struct timeval tv; 361 int tticks; 362 363 if (kq_ncallouts >= kq_calloutmax) 364 return (ENOMEM); 365 kq_ncallouts++; 366 367 tv.tv_sec = kn->kn_sdata / 1000; 368 tv.tv_usec = (kn->kn_sdata % 1000) * 1000; 369 tticks = tvtohz_high(&tv); 370 371 kn->kn_flags |= EV_CLEAR; /* automatically set */ 372 MALLOC(calloutp, struct callout *, sizeof(*calloutp), 373 M_KQUEUE, M_WAITOK); 374 callout_init(calloutp); 375 kn->kn_hook = (caddr_t)calloutp; 376 callout_reset(calloutp, tticks, filt_timerexpire, kn); 377 378 return (0); 379 } 380 381 static void 382 filt_timerdetach(struct knote *kn) 383 { 384 struct callout *calloutp; 385 386 calloutp = (struct callout *)kn->kn_hook; 387 callout_stop(calloutp); 388 FREE(calloutp, M_KQUEUE); 389 kq_ncallouts--; 390 } 391 392 static int 393 filt_timer(struct knote *kn, long hint) 394 { 395 396 return (kn->kn_data != 0); 397 } 398 399 /* 400 * Initialize a kqueue. 401 * 402 * NOTE: The lwp/proc code initializes a kqueue for select/poll ops. 403 * 404 * MPSAFE 405 */ 406 void 407 kqueue_init(struct kqueue *kq, struct filedesc *fdp) 408 { 409 TAILQ_INIT(&kq->kq_knpend); 410 TAILQ_INIT(&kq->kq_knlist); 411 kq->kq_count = 0; 412 kq->kq_fdp = fdp; 413 SLIST_INIT(&kq->kq_kqinfo.ki_note); 414 } 415 416 /* 417 * Terminate a kqueue. Freeing the actual kq itself is left up to the 418 * caller (it might be embedded in a lwp so we don't do it here). 419 */ 420 void 421 kqueue_terminate(struct kqueue *kq) 422 { 423 struct knote *kn; 424 425 lwkt_gettoken(&kq_token); 426 while ((kn = TAILQ_FIRST(&kq->kq_knlist)) != NULL) 427 knote_detach_and_drop(kn); 428 429 if (kq->kq_knhash) { 430 kfree(kq->kq_knhash, M_KQUEUE); 431 kq->kq_knhash = NULL; 432 kq->kq_knhashmask = 0; 433 } 434 lwkt_reltoken(&kq_token); 435 } 436 437 /* 438 * MPSAFE 439 */ 440 int 441 sys_kqueue(struct kqueue_args *uap) 442 { 443 struct thread *td = curthread; 444 struct kqueue *kq; 445 struct file *fp; 446 int fd, error; 447 448 error = falloc(td->td_lwp, &fp, &fd); 449 if (error) 450 return (error); 451 fp->f_flag = FREAD | FWRITE; 452 fp->f_type = DTYPE_KQUEUE; 453 fp->f_ops = &kqueueops; 454 455 kq = kmalloc(sizeof(struct kqueue), M_KQUEUE, M_WAITOK | M_ZERO); 456 kqueue_init(kq, td->td_proc->p_fd); 457 fp->f_data = kq; 458 459 fsetfd(kq->kq_fdp, fp, fd); 460 uap->sysmsg_result = fd; 461 fdrop(fp); 462 return (error); 463 } 464 465 /* 466 * Copy 'count' items into the destination list pointed to by uap->eventlist. 467 */ 468 static int 469 kevent_copyout(void *arg, struct kevent *kevp, int count, int *res) 470 { 471 struct kevent_copyin_args *kap; 472 int error; 473 474 kap = (struct kevent_copyin_args *)arg; 475 476 error = copyout(kevp, kap->ka->eventlist, count * sizeof(*kevp)); 477 if (error == 0) { 478 kap->ka->eventlist += count; 479 *res += count; 480 } else { 481 *res = -1; 482 } 483 484 return (error); 485 } 486 487 /* 488 * Copy at most 'max' items from the list pointed to by kap->changelist, 489 * return number of items in 'events'. 490 */ 491 static int 492 kevent_copyin(void *arg, struct kevent *kevp, int max, int *events) 493 { 494 struct kevent_copyin_args *kap; 495 int error, count; 496 497 kap = (struct kevent_copyin_args *)arg; 498 499 count = min(kap->ka->nchanges - kap->pchanges, max); 500 error = copyin(kap->ka->changelist, kevp, count * sizeof *kevp); 501 if (error == 0) { 502 kap->ka->changelist += count; 503 kap->pchanges += count; 504 *events = count; 505 } 506 507 return (error); 508 } 509 510 /* 511 * MPSAFE 512 */ 513 int 514 kern_kevent(struct kqueue *kq, int nevents, int *res, void *uap, 515 k_copyin_fn kevent_copyinfn, k_copyout_fn kevent_copyoutfn, 516 struct timespec *tsp_in) 517 { 518 struct kevent *kevp; 519 struct timespec *tsp; 520 int i, n, total, error, nerrors = 0; 521 int lres; 522 int limit = kq_checkloop; 523 struct kevent kev[KQ_NEVENTS]; 524 struct knote marker; 525 526 tsp = tsp_in; 527 *res = 0; 528 529 lwkt_gettoken(&kq_token); 530 for ( ;; ) { 531 n = 0; 532 error = kevent_copyinfn(uap, kev, KQ_NEVENTS, &n); 533 if (error) 534 goto done; 535 if (n == 0) 536 break; 537 for (i = 0; i < n; i++) { 538 kevp = &kev[i]; 539 kevp->flags &= ~EV_SYSFLAGS; 540 error = kqueue_register(kq, kevp); 541 542 /* 543 * If a registration returns an error we 544 * immediately post the error. The kevent() 545 * call itself will fail with the error if 546 * no space is available for posting. 547 * 548 * Such errors normally bypass the timeout/blocking 549 * code. However, if the copyoutfn function refuses 550 * to post the error (see sys_poll()), then we 551 * ignore it too. 552 */ 553 if (error) { 554 kevp->flags = EV_ERROR; 555 kevp->data = error; 556 lres = *res; 557 kevent_copyoutfn(uap, kevp, 1, res); 558 if (lres != *res) { 559 nevents--; 560 nerrors++; 561 } 562 } 563 } 564 } 565 if (nerrors) { 566 error = 0; 567 goto done; 568 } 569 570 /* 571 * Acquire/wait for events - setup timeout 572 */ 573 if (tsp != NULL) { 574 struct timespec ats; 575 576 if (tsp->tv_sec || tsp->tv_nsec) { 577 nanouptime(&ats); 578 timespecadd(tsp, &ats); /* tsp = target time */ 579 } 580 } 581 582 /* 583 * Loop as required. 584 * 585 * Collect as many events as we can. Sleeping on successive 586 * loops is disabled if copyoutfn has incremented (*res). 587 * 588 * The loop stops if an error occurs, all events have been 589 * scanned (the marker has been reached), or fewer than the 590 * maximum number of events is found. 591 * 592 * The copyoutfn function does not have to increment (*res) in 593 * order for the loop to continue. 594 * 595 * NOTE: doselect() usually passes 0x7FFFFFFF for nevents. 596 */ 597 total = 0; 598 error = 0; 599 marker.kn_filter = EVFILT_MARKER; 600 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 601 while ((n = nevents - total) > 0) { 602 if (n > KQ_NEVENTS) 603 n = KQ_NEVENTS; 604 605 /* 606 * If no events are pending sleep until timeout (if any) 607 * or an event occurs. 608 * 609 * After the sleep completes the marker is moved to the 610 * end of the list, making any received events available 611 * to our scan. 612 */ 613 if (kq->kq_count == 0 && *res == 0) { 614 error = kqueue_sleep(kq, tsp); 615 if (error) 616 break; 617 618 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 619 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 620 } 621 622 /* 623 * Process all received events 624 * Account for all non-spurious events in our total 625 */ 626 i = kqueue_scan(kq, kev, n, &marker); 627 if (i) { 628 lres = *res; 629 error = kevent_copyoutfn(uap, kev, i, res); 630 total += *res - lres; 631 if (error) 632 break; 633 } 634 if (limit && --limit == 0) 635 panic("kqueue: checkloop failed i=%d", i); 636 637 /* 638 * Normally when fewer events are returned than requested 639 * we can stop. However, if only spurious events were 640 * collected the copyout will not bump (*res) and we have 641 * to continue. 642 */ 643 if (i < n && *res) 644 break; 645 646 /* 647 * Deal with an edge case where spurious events can cause 648 * a loop to occur without moving the marker. This can 649 * prevent kqueue_scan() from picking up new events which 650 * race us. We must be sure to move the marker for this 651 * case. 652 * 653 * NOTE: We do not want to move the marker if events 654 * were scanned because normal kqueue operations 655 * may reactivate events. Moving the marker in 656 * that case could result in duplicates for the 657 * same event. 658 */ 659 if (i == 0) { 660 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 661 TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe); 662 } 663 } 664 TAILQ_REMOVE(&kq->kq_knpend, &marker, kn_tqe); 665 666 /* Timeouts do not return EWOULDBLOCK. */ 667 if (error == EWOULDBLOCK) 668 error = 0; 669 670 done: 671 lwkt_reltoken(&kq_token); 672 return (error); 673 } 674 675 /* 676 * MPALMOSTSAFE 677 */ 678 int 679 sys_kevent(struct kevent_args *uap) 680 { 681 struct thread *td = curthread; 682 struct proc *p = td->td_proc; 683 struct timespec ts, *tsp; 684 struct kqueue *kq; 685 struct file *fp = NULL; 686 struct kevent_copyin_args *kap, ka; 687 int error; 688 689 if (uap->timeout) { 690 error = copyin(uap->timeout, &ts, sizeof(ts)); 691 if (error) 692 return (error); 693 tsp = &ts; 694 } else { 695 tsp = NULL; 696 } 697 698 fp = holdfp(p->p_fd, uap->fd, -1); 699 if (fp == NULL) 700 return (EBADF); 701 if (fp->f_type != DTYPE_KQUEUE) { 702 fdrop(fp); 703 return (EBADF); 704 } 705 706 kq = (struct kqueue *)fp->f_data; 707 708 kap = &ka; 709 kap->ka = uap; 710 kap->pchanges = 0; 711 712 error = kern_kevent(kq, uap->nevents, &uap->sysmsg_result, kap, 713 kevent_copyin, kevent_copyout, tsp); 714 715 fdrop(fp); 716 717 return (error); 718 } 719 720 int 721 kqueue_register(struct kqueue *kq, struct kevent *kev) 722 { 723 struct filedesc *fdp = kq->kq_fdp; 724 struct filterops *fops; 725 struct file *fp = NULL; 726 struct knote *kn = NULL; 727 int error = 0; 728 729 if (kev->filter < 0) { 730 if (kev->filter + EVFILT_SYSCOUNT < 0) 731 return (EINVAL); 732 fops = sysfilt_ops[~kev->filter]; /* to 0-base index */ 733 } else { 734 /* 735 * XXX 736 * filter attach routine is responsible for insuring that 737 * the identifier can be attached to it. 738 */ 739 kprintf("unknown filter: %d\n", kev->filter); 740 return (EINVAL); 741 } 742 743 lwkt_gettoken(&kq_token); 744 if (fops->f_flags & FILTEROP_ISFD) { 745 /* validate descriptor */ 746 fp = holdfp(fdp, kev->ident, -1); 747 if (fp == NULL) { 748 lwkt_reltoken(&kq_token); 749 return (EBADF); 750 } 751 752 SLIST_FOREACH(kn, &fp->f_klist, kn_link) { 753 if (kn->kn_kq == kq && 754 kn->kn_filter == kev->filter && 755 kn->kn_id == kev->ident) { 756 break; 757 } 758 } 759 } else { 760 if (kq->kq_knhashmask) { 761 struct klist *list; 762 763 list = &kq->kq_knhash[ 764 KN_HASH((u_long)kev->ident, kq->kq_knhashmask)]; 765 SLIST_FOREACH(kn, list, kn_link) { 766 if (kn->kn_id == kev->ident && 767 kn->kn_filter == kev->filter) 768 break; 769 } 770 } 771 } 772 773 if (kn == NULL && ((kev->flags & EV_ADD) == 0)) { 774 error = ENOENT; 775 goto done; 776 } 777 778 /* 779 * kn now contains the matching knote, or NULL if no match 780 */ 781 if (kev->flags & EV_ADD) { 782 if (kn == NULL) { 783 kn = knote_alloc(); 784 if (kn == NULL) { 785 error = ENOMEM; 786 goto done; 787 } 788 kn->kn_fp = fp; 789 kn->kn_kq = kq; 790 kn->kn_fop = fops; 791 792 /* 793 * apply reference count to knote structure, and 794 * do not release it at the end of this routine. 795 */ 796 fp = NULL; 797 798 kn->kn_sfflags = kev->fflags; 799 kn->kn_sdata = kev->data; 800 kev->fflags = 0; 801 kev->data = 0; 802 kn->kn_kevent = *kev; 803 804 /* 805 * Interlock against creation/deletion races due 806 * to f_attach() blocking. knote_attach() will set 807 * KN_CREATING. 808 */ 809 knote_attach(kn); 810 if ((error = filter_attach(kn)) != 0) { 811 kn->kn_status |= KN_DELETING; 812 knote_drop(kn); 813 goto done; 814 } 815 kn->kn_status &= ~KN_CREATING; 816 817 /* 818 * Interlock against close races which remove our 819 * knotes. We do not want to end up with a knote 820 * on a closed descriptor. 821 */ 822 if ((fops->f_flags & FILTEROP_ISFD) && 823 (error = checkfdclosed(fdp, kev->ident, kn->kn_fp)) != 0) { 824 knote_detach_and_drop(kn); 825 goto done; 826 } 827 } else { 828 /* 829 * The user may change some filter values after the 830 * initial EV_ADD, but doing so will not reset any 831 * filter which have already been triggered. 832 */ 833 kn->kn_sfflags = kev->fflags; 834 kn->kn_sdata = kev->data; 835 kn->kn_kevent.udata = kev->udata; 836 } 837 838 if (filter_event(kn, 0)) 839 KNOTE_ACTIVATE(kn); 840 } else if (kev->flags & EV_DELETE) { 841 knote_detach_and_drop(kn); 842 goto done; 843 } 844 845 if ((kev->flags & EV_DISABLE) && 846 ((kn->kn_status & KN_DISABLED) == 0)) { 847 kn->kn_status |= KN_DISABLED; 848 } 849 850 if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) { 851 kn->kn_status &= ~KN_DISABLED; 852 if ((kn->kn_status & KN_ACTIVE) && 853 ((kn->kn_status & KN_QUEUED) == 0)) 854 knote_enqueue(kn); 855 } 856 857 done: 858 lwkt_reltoken(&kq_token); 859 if (fp != NULL) 860 fdrop(fp); 861 return (error); 862 } 863 864 /* 865 * Block as necessary until the target time is reached. 866 * If tsp is NULL we block indefinitely. If tsp->ts_secs/nsecs are both 867 * 0 we do not block at all. 868 */ 869 static int 870 kqueue_sleep(struct kqueue *kq, struct timespec *tsp) 871 { 872 int error = 0; 873 874 if (tsp == NULL) { 875 kq->kq_state |= KQ_SLEEP; 876 error = tsleep(kq, PCATCH, "kqread", 0); 877 } else if (tsp->tv_sec == 0 && tsp->tv_nsec == 0) { 878 error = EWOULDBLOCK; 879 } else { 880 struct timespec ats; 881 struct timespec atx = *tsp; 882 int timeout; 883 884 nanouptime(&ats); 885 timespecsub(&atx, &ats); 886 if (ats.tv_sec < 0) { 887 error = EWOULDBLOCK; 888 } else { 889 timeout = atx.tv_sec > 24 * 60 * 60 ? 890 24 * 60 * 60 * hz : tstohz_high(&atx); 891 kq->kq_state |= KQ_SLEEP; 892 error = tsleep(kq, PCATCH, "kqread", timeout); 893 } 894 } 895 896 /* don't restart after signals... */ 897 if (error == ERESTART) 898 return (EINTR); 899 900 return (error); 901 } 902 903 /* 904 * Scan the kqueue, return the number of active events placed in kevp up 905 * to count. 906 * 907 * Continuous mode events may get recycled, do not continue scanning past 908 * marker unless no events have been collected. 909 */ 910 static int 911 kqueue_scan(struct kqueue *kq, struct kevent *kevp, int count, 912 struct knote *marker) 913 { 914 struct knote *kn, local_marker; 915 int total; 916 917 total = 0; 918 local_marker.kn_filter = EVFILT_MARKER; 919 920 /* 921 * Collect events. 922 */ 923 TAILQ_INSERT_HEAD(&kq->kq_knpend, &local_marker, kn_tqe); 924 while (count) { 925 kn = TAILQ_NEXT(&local_marker, kn_tqe); 926 if (kn->kn_filter == EVFILT_MARKER) { 927 /* Marker reached, we are done */ 928 if (kn == marker) 929 break; 930 931 /* Move local marker past some other threads marker */ 932 kn = TAILQ_NEXT(kn, kn_tqe); 933 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe); 934 TAILQ_INSERT_BEFORE(kn, &local_marker, kn_tqe); 935 continue; 936 } 937 938 /* 939 * Remove the event for processing. 940 * 941 * WARNING! We must leave KN_QUEUED set to prevent the 942 * event from being KNOTE()d again while we 943 * potentially block in the filter function. 944 */ 945 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe); 946 kq->kq_count--; 947 948 /* 949 * Even though close/dup2 will clean out pending knotes this 950 * code is MPSAFE and it is possible to race a close inbetween 951 * the removal of its descriptor and the clearing out of the 952 * knote(s). 953 * 954 * In this case we must ensure that the knote is not queued 955 * to knpend or we risk an infinite kernel loop calling 956 * kscan, because the select/poll code will not be able to 957 * delete the event. 958 */ 959 if ((kn->kn_fop->f_flags & FILTEROP_ISFD) && 960 checkfdclosed(kq->kq_fdp, kn->kn_kevent.ident, kn->kn_fp)) { 961 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE); 962 continue; 963 } 964 965 /* 966 * If disabled we ensure the event is not queued but leave 967 * its active bit set. On re-enablement the event may be 968 * immediately triggered. 969 */ 970 if (kn->kn_status & KN_DISABLED) { 971 kn->kn_status &= ~KN_QUEUED; 972 continue; 973 } 974 975 /* 976 * If not running in one-shot mode and the event is no 977 * longer present we ensure it is removed from the queue and 978 * ignore it. 979 */ 980 if ((kn->kn_flags & EV_ONESHOT) == 0 && 981 filter_event(kn, 0) == 0) { 982 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE); 983 continue; 984 } 985 986 *kevp++ = kn->kn_kevent; 987 ++total; 988 --count; 989 990 /* 991 * Post-event action on the note 992 */ 993 if (kn->kn_flags & EV_ONESHOT) { 994 kn->kn_status &= ~KN_QUEUED; 995 knote_detach_and_drop(kn); 996 } else if (kn->kn_flags & EV_CLEAR) { 997 kn->kn_data = 0; 998 kn->kn_fflags = 0; 999 kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE); 1000 } else { 1001 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe); 1002 kq->kq_count++; 1003 } 1004 } 1005 TAILQ_REMOVE(&kq->kq_knpend, &local_marker, kn_tqe); 1006 1007 return (total); 1008 } 1009 1010 /* 1011 * XXX 1012 * This could be expanded to call kqueue_scan, if desired. 1013 * 1014 * MPSAFE 1015 */ 1016 static int 1017 kqueue_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags) 1018 { 1019 return (ENXIO); 1020 } 1021 1022 /* 1023 * MPSAFE 1024 */ 1025 static int 1026 kqueue_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags) 1027 { 1028 return (ENXIO); 1029 } 1030 1031 /* 1032 * MPALMOSTSAFE 1033 */ 1034 static int 1035 kqueue_ioctl(struct file *fp, u_long com, caddr_t data, 1036 struct ucred *cred, struct sysmsg *msg) 1037 { 1038 struct kqueue *kq; 1039 int error; 1040 1041 lwkt_gettoken(&kq_token); 1042 kq = (struct kqueue *)fp->f_data; 1043 1044 switch(com) { 1045 case FIOASYNC: 1046 if (*(int *)data) 1047 kq->kq_state |= KQ_ASYNC; 1048 else 1049 kq->kq_state &= ~KQ_ASYNC; 1050 error = 0; 1051 break; 1052 case FIOSETOWN: 1053 error = fsetown(*(int *)data, &kq->kq_sigio); 1054 break; 1055 default: 1056 error = ENOTTY; 1057 break; 1058 } 1059 lwkt_reltoken(&kq_token); 1060 return (error); 1061 } 1062 1063 /* 1064 * MPSAFE 1065 */ 1066 static int 1067 kqueue_stat(struct file *fp, struct stat *st, struct ucred *cred) 1068 { 1069 struct kqueue *kq = (struct kqueue *)fp->f_data; 1070 1071 bzero((void *)st, sizeof(*st)); 1072 st->st_size = kq->kq_count; 1073 st->st_blksize = sizeof(struct kevent); 1074 st->st_mode = S_IFIFO; 1075 return (0); 1076 } 1077 1078 /* 1079 * MPSAFE 1080 */ 1081 static int 1082 kqueue_close(struct file *fp) 1083 { 1084 struct kqueue *kq = (struct kqueue *)fp->f_data; 1085 1086 kqueue_terminate(kq); 1087 1088 fp->f_data = NULL; 1089 funsetown(kq->kq_sigio); 1090 1091 kfree(kq, M_KQUEUE); 1092 return (0); 1093 } 1094 1095 static void 1096 kqueue_wakeup(struct kqueue *kq) 1097 { 1098 if (kq->kq_state & KQ_SLEEP) { 1099 kq->kq_state &= ~KQ_SLEEP; 1100 wakeup(kq); 1101 } 1102 KNOTE(&kq->kq_kqinfo.ki_note, 0); 1103 } 1104 1105 /* 1106 * Calls filterops f_attach function, acquiring mplock if filter is not 1107 * marked as FILTEROP_MPSAFE. 1108 */ 1109 static int 1110 filter_attach(struct knote *kn) 1111 { 1112 int ret; 1113 1114 if (!(kn->kn_fop->f_flags & FILTEROP_MPSAFE)) { 1115 get_mplock(); 1116 ret = kn->kn_fop->f_attach(kn); 1117 rel_mplock(); 1118 } else { 1119 ret = kn->kn_fop->f_attach(kn); 1120 } 1121 1122 return (ret); 1123 } 1124 1125 /* 1126 * Detach the knote and drop it, destroying the knote. 1127 * 1128 * Calls filterops f_detach function, acquiring mplock if filter is not 1129 * marked as FILTEROP_MPSAFE. 1130 * 1131 * This can race due to the MP lock and/or locks acquired by f_detach, 1132 * so we interlock with KN_DELETING. It is also possible to race 1133 * a create for the same reason if userland tries to delete the knote 1134 * before the create is complete. 1135 */ 1136 static void 1137 knote_detach_and_drop(struct knote *kn) 1138 { 1139 if (kn->kn_status & (KN_CREATING | KN_DELETING)) 1140 return; 1141 kn->kn_status |= KN_DELETING; 1142 1143 if (kn->kn_fop->f_flags & FILTEROP_MPSAFE) { 1144 kn->kn_fop->f_detach(kn); 1145 } else { 1146 get_mplock(); 1147 kn->kn_fop->f_detach(kn); 1148 rel_mplock(); 1149 } 1150 knote_drop(kn); 1151 } 1152 1153 /* 1154 * Calls filterops f_event function, acquiring mplock if filter is not 1155 * marked as FILTEROP_MPSAFE. 1156 * 1157 * If the knote is in the middle of being created or deleted we cannot 1158 * safely call the filter op. 1159 */ 1160 static int 1161 filter_event(struct knote *kn, long hint) 1162 { 1163 int ret; 1164 1165 if (kn->kn_status & (KN_CREATING | KN_DELETING)) 1166 return(0); 1167 1168 if (!(kn->kn_fop->f_flags & FILTEROP_MPSAFE)) { 1169 get_mplock(); 1170 ret = kn->kn_fop->f_event(kn, hint); 1171 rel_mplock(); 1172 } else { 1173 ret = kn->kn_fop->f_event(kn, hint); 1174 } 1175 1176 return (ret); 1177 } 1178 1179 /* 1180 * walk down a list of knotes, activating them if their event has triggered. 1181 */ 1182 void 1183 knote(struct klist *list, long hint) 1184 { 1185 struct knote *kn; 1186 1187 lwkt_gettoken(&kq_token); 1188 SLIST_FOREACH(kn, list, kn_next) { 1189 if (filter_event(kn, hint)) 1190 KNOTE_ACTIVATE(kn); 1191 } 1192 lwkt_reltoken(&kq_token); 1193 } 1194 1195 /* 1196 * insert knote at head of klist 1197 * 1198 * Requires: kq_token 1199 */ 1200 void 1201 knote_insert(struct klist *klist, struct knote *kn) 1202 { 1203 lwkt_gettoken(&kq_token); 1204 SLIST_INSERT_HEAD(klist, kn, kn_next); 1205 lwkt_reltoken(&kq_token); 1206 } 1207 1208 /* 1209 * remove knote from a klist 1210 * 1211 * Requires: kq_token 1212 */ 1213 void 1214 knote_remove(struct klist *klist, struct knote *kn) 1215 { 1216 lwkt_gettoken(&kq_token); 1217 SLIST_REMOVE(klist, kn, knote, kn_next); 1218 lwkt_reltoken(&kq_token); 1219 } 1220 1221 /* 1222 * remove all knotes from a specified klist 1223 */ 1224 void 1225 knote_empty(struct klist *list) 1226 { 1227 struct knote *kn; 1228 1229 lwkt_gettoken(&kq_token); 1230 while ((kn = SLIST_FIRST(list)) != NULL) 1231 knote_detach_and_drop(kn); 1232 lwkt_reltoken(&kq_token); 1233 } 1234 1235 /* 1236 * remove all knotes referencing a specified fd 1237 */ 1238 void 1239 knote_fdclose(struct file *fp, struct filedesc *fdp, int fd) 1240 { 1241 struct knote *kn; 1242 1243 lwkt_gettoken(&kq_token); 1244 restart: 1245 SLIST_FOREACH(kn, &fp->f_klist, kn_link) { 1246 if (kn->kn_kq->kq_fdp == fdp && kn->kn_id == fd) { 1247 knote_detach_and_drop(kn); 1248 goto restart; 1249 } 1250 } 1251 lwkt_reltoken(&kq_token); 1252 } 1253 1254 static void 1255 knote_attach(struct knote *kn) 1256 { 1257 struct klist *list; 1258 struct kqueue *kq = kn->kn_kq; 1259 1260 if (kn->kn_fop->f_flags & FILTEROP_ISFD) { 1261 KKASSERT(kn->kn_fp); 1262 list = &kn->kn_fp->f_klist; 1263 } else { 1264 if (kq->kq_knhashmask == 0) 1265 kq->kq_knhash = hashinit(KN_HASHSIZE, M_KQUEUE, 1266 &kq->kq_knhashmask); 1267 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)]; 1268 } 1269 SLIST_INSERT_HEAD(list, kn, kn_link); 1270 TAILQ_INSERT_HEAD(&kq->kq_knlist, kn, kn_kqlink); 1271 kn->kn_status = KN_CREATING; 1272 } 1273 1274 static void 1275 knote_drop(struct knote *kn) 1276 { 1277 struct kqueue *kq; 1278 struct klist *list; 1279 1280 kq = kn->kn_kq; 1281 1282 if (kn->kn_fop->f_flags & FILTEROP_ISFD) 1283 list = &kn->kn_fp->f_klist; 1284 else 1285 list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)]; 1286 1287 SLIST_REMOVE(list, kn, knote, kn_link); 1288 TAILQ_REMOVE(&kq->kq_knlist, kn, kn_kqlink); 1289 if (kn->kn_status & KN_QUEUED) 1290 knote_dequeue(kn); 1291 if (kn->kn_fop->f_flags & FILTEROP_ISFD) { 1292 fdrop(kn->kn_fp); 1293 kn->kn_fp = NULL; 1294 } 1295 knote_free(kn); 1296 } 1297 1298 static void 1299 knote_enqueue(struct knote *kn) 1300 { 1301 struct kqueue *kq = kn->kn_kq; 1302 1303 KASSERT((kn->kn_status & KN_QUEUED) == 0, ("knote already queued")); 1304 1305 TAILQ_INSERT_TAIL(&kq->kq_knpend, kn, kn_tqe); 1306 kn->kn_status |= KN_QUEUED; 1307 ++kq->kq_count; 1308 1309 /* 1310 * Send SIGIO on request (typically set up as a mailbox signal) 1311 */ 1312 if (kq->kq_sigio && (kq->kq_state & KQ_ASYNC) && kq->kq_count == 1) 1313 pgsigio(kq->kq_sigio, SIGIO, 0); 1314 1315 kqueue_wakeup(kq); 1316 } 1317 1318 static void 1319 knote_dequeue(struct knote *kn) 1320 { 1321 struct kqueue *kq = kn->kn_kq; 1322 1323 KASSERT(kn->kn_status & KN_QUEUED, ("knote not queued")); 1324 1325 TAILQ_REMOVE(&kq->kq_knpend, kn, kn_tqe); 1326 kn->kn_status &= ~KN_QUEUED; 1327 kq->kq_count--; 1328 } 1329 1330 static void 1331 knote_init(void) 1332 { 1333 knote_zone = zinit("KNOTE", sizeof(struct knote), 0, 0, 1); 1334 } 1335 SYSINIT(knote, SI_SUB_PSEUDO, SI_ORDER_ANY, knote_init, NULL) 1336 1337 static struct knote * 1338 knote_alloc(void) 1339 { 1340 return ((struct knote *)zalloc(knote_zone)); 1341 } 1342 1343 static void 1344 knote_free(struct knote *kn) 1345 { 1346 zfree(knote_zone, kn); 1347 } 1348