Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/common/io/devpoll.c
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1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 27 #include <sys/types.h> 28 #include <sys/devops.h> 29 #include <sys/conf.h> 30 #include <sys/modctl.h> 31 #include <sys/sunddi.h> 32 #include <sys/stat.h> 33 #include <sys/poll_impl.h> 34 #include <sys/errno.h> 35 #include <sys/kmem.h> 36 #include <sys/mkdev.h> 37 #include <sys/debug.h> 38 #include <sys/file.h> 39 #include <sys/sysmacros.h> 40 #include <sys/systm.h> 41 #include <sys/bitmap.h> 42 #include <sys/devpoll.h> 43 #include <sys/rctl.h> 44 #include <sys/resource.h> 45 46 #define RESERVED 1 47 48 /* local data struct */ 49 static dp_entry_t **devpolltbl; /* dev poll entries */ 50 static size_t dptblsize; 51 52 static kmutex_t devpoll_lock; /* lock protecting dev tbl */ 53 int devpoll_init; /* is /dev/poll initialized already */ 54 55 /* device local functions */ 56 57 static int dpopen(dev_t *devp, int flag, int otyp, cred_t *credp); 58 static int dpwrite(dev_t dev, struct uio *uiop, cred_t *credp); 59 static int dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, 60 int *rvalp); 61 static int dppoll(dev_t dev, short events, int anyyet, short *reventsp, 62 struct pollhead **phpp); 63 static int dpclose(dev_t dev, int flag, int otyp, cred_t *credp); 64 static dev_info_t *dpdevi; 65 66 67 static struct cb_ops dp_cb_ops = { 68 dpopen, /* open */ 69 dpclose, /* close */ 70 nodev, /* strategy */ 71 nodev, /* print */ 72 nodev, /* dump */ 73 nodev, /* read */ 74 dpwrite, /* write */ 75 dpioctl, /* ioctl */ 76 nodev, /* devmap */ 77 nodev, /* mmap */ 78 nodev, /* segmap */ 79 dppoll, /* poll */ 80 ddi_prop_op, /* prop_op */ 81 (struct streamtab *)0, /* streamtab */ 82 D_MP, /* flags */ 83 CB_REV, /* cb_ops revision */ 84 nodev, /* aread */ 85 nodev /* awrite */ 86 }; 87 88 static int dpattach(dev_info_t *, ddi_attach_cmd_t); 89 static int dpdetach(dev_info_t *, ddi_detach_cmd_t); 90 static int dpinfo(dev_info_t *, ddi_info_cmd_t, void *, void **); 91 92 static struct dev_ops dp_ops = { 93 DEVO_REV, /* devo_rev */ 94 0, /* refcnt */ 95 dpinfo, /* info */ 96 nulldev, /* identify */ 97 nulldev, /* probe */ 98 dpattach, /* attach */ 99 dpdetach, /* detach */ 100 nodev, /* reset */ 101 &dp_cb_ops, /* driver operations */ 102 (struct bus_ops *)NULL, /* bus operations */ 103 nulldev, /* power */ 104 ddi_quiesce_not_needed, /* quiesce */ 105 }; 106 107 108 static struct modldrv modldrv = { 109 &mod_driverops, /* type of module - a driver */ 110 "/dev/poll driver", 111 &dp_ops, 112 }; 113 114 static struct modlinkage modlinkage = { 115 MODREV_1, 116 (void *)&modldrv, 117 NULL 118 }; 119 120 /* 121 * Locking Design 122 * 123 * The /dev/poll driver shares most of its code with poll sys call whose 124 * code is in common/syscall/poll.c. In poll(2) design, the pollcache 125 * structure is per lwp. An implicit assumption is made there that some 126 * portion of pollcache will never be touched by other lwps. E.g., in 127 * poll(2) design, no lwp will ever need to grow bitmap of other lwp. 128 * This assumption is not true for /dev/poll; hence the need for extra 129 * locking. 130 * 131 * To allow more parallelism, each /dev/poll file descriptor (indexed by 132 * minor number) has its own lock. Since read (dpioctl) is a much more 133 * frequent operation than write, we want to allow multiple reads on same 134 * /dev/poll fd. However, we prevent writes from being starved by giving 135 * priority to write operation. Theoretically writes can starve reads as 136 * well. But in practical sense this is not important because (1) writes 137 * happens less often than reads, and (2) write operation defines the 138 * content of poll fd a cache set. If writes happens so often that they 139 * can starve reads, that means the cached set is very unstable. It may 140 * not make sense to read an unstable cache set anyway. Therefore, the 141 * writers starving readers case is not handled in this design. 142 */ 143 144 int 145 _init() 146 { 147 int error; 148 149 dptblsize = DEVPOLLSIZE; 150 devpolltbl = kmem_zalloc(sizeof (caddr_t) * dptblsize, KM_SLEEP); 151 mutex_init(&devpoll_lock, NULL, MUTEX_DEFAULT, NULL); 152 devpoll_init = 1; 153 if ((error = mod_install(&modlinkage)) != 0) { 154 mutex_destroy(&devpoll_lock); 155 kmem_free(devpolltbl, sizeof (caddr_t) * dptblsize); 156 devpoll_init = 0; 157 } 158 return (error); 159 } 160 161 int 162 _fini() 163 { 164 int error; 165 166 if ((error = mod_remove(&modlinkage)) != 0) { 167 return (error); 168 } 169 mutex_destroy(&devpoll_lock); 170 kmem_free(devpolltbl, sizeof (caddr_t) * dptblsize); 171 return (0); 172 } 173 174 int 175 _info(struct modinfo *modinfop) 176 { 177 return (mod_info(&modlinkage, modinfop)); 178 } 179 180 /*ARGSUSED*/ 181 static int 182 dpattach(dev_info_t *devi, ddi_attach_cmd_t cmd) 183 { 184 if (ddi_create_minor_node(devi, "poll", S_IFCHR, 0, DDI_PSEUDO, NULL) 185 == DDI_FAILURE) { 186 ddi_remove_minor_node(devi, NULL); 187 return (DDI_FAILURE); 188 } 189 dpdevi = devi; 190 return (DDI_SUCCESS); 191 } 192 193 static int 194 dpdetach(dev_info_t *devi, ddi_detach_cmd_t cmd) 195 { 196 if (cmd != DDI_DETACH) 197 return (DDI_FAILURE); 198 199 ddi_remove_minor_node(devi, NULL); 200 return (DDI_SUCCESS); 201 } 202 203 /* ARGSUSED */ 204 static int 205 dpinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result) 206 { 207 int error; 208 209 switch (infocmd) { 210 case DDI_INFO_DEVT2DEVINFO: 211 *result = (void *)dpdevi; 212 error = DDI_SUCCESS; 213 break; 214 case DDI_INFO_DEVT2INSTANCE: 215 *result = (void *)0; 216 error = DDI_SUCCESS; 217 break; 218 default: 219 error = DDI_FAILURE; 220 } 221 return (error); 222 } 223 224 /* 225 * dp_pcache_poll has similar logic to pcache_poll() in poll.c. The major 226 * differences are: (1) /dev/poll requires scanning the bitmap starting at 227 * where it was stopped last time, instead of always starting from 0, 228 * (2) since user may not have cleaned up the cached fds when they are 229 * closed, some polldats in cache may refer to closed or reused fds. We 230 * need to check for those cases. 231 * 232 * NOTE: Upon closing an fd, automatic poll cache cleanup is done for 233 * poll(2) caches but NOT for /dev/poll caches. So expect some 234 * stale entries! 235 */ 236 static int 237 dp_pcache_poll(pollfd_t *pfdp, pollcache_t *pcp, nfds_t nfds, int *fdcntp) 238 { 239 int start, ostart, end; 240 int fdcnt, fd; 241 boolean_t done; 242 file_t *fp; 243 short revent; 244 boolean_t no_wrap; 245 pollhead_t *php; 246 polldat_t *pdp; 247 int error = 0; 248 249 ASSERT(MUTEX_HELD(&pcp->pc_lock)); 250 if (pcp->pc_bitmap == NULL) { 251 /* 252 * No Need to search because no poll fd 253 * has been cached. 254 */ 255 return (error); 256 } 257 retry: 258 start = ostart = pcp->pc_mapstart; 259 end = pcp->pc_mapend; 260 php = NULL; 261 262 if (start == 0) { 263 /* 264 * started from every begining, no need to wrap around. 265 */ 266 no_wrap = B_TRUE; 267 } else { 268 no_wrap = B_FALSE; 269 } 270 done = B_FALSE; 271 fdcnt = 0; 272 while ((fdcnt < nfds) && !done) { 273 php = NULL; 274 revent = 0; 275 /* 276 * Examine the bit map in a circular fashion 277 * to avoid starvation. Always resume from 278 * last stop. Scan till end of the map. Then 279 * wrap around. 280 */ 281 fd = bt_getlowbit(pcp->pc_bitmap, start, end); 282 ASSERT(fd <= end); 283 if (fd >= 0) { 284 if (fd == end) { 285 if (no_wrap) { 286 done = B_TRUE; 287 } else { 288 start = 0; 289 end = ostart - 1; 290 no_wrap = B_TRUE; 291 } 292 } else { 293 start = fd + 1; 294 } 295 pdp = pcache_lookup_fd(pcp, fd); 296 repoll: 297 ASSERT(pdp != NULL); 298 ASSERT(pdp->pd_fd == fd); 299 if (pdp->pd_fp == NULL) { 300 /* 301 * The fd is POLLREMOVed. This fd is 302 * logically no longer cached. So move 303 * on to the next one. 304 */ 305 continue; 306 } 307 if ((fp = getf(fd)) == NULL) { 308 /* 309 * The fd has been closed, but user has not 310 * done a POLLREMOVE on this fd yet. Instead 311 * of cleaning it here implicitly, we return 312 * POLLNVAL. This is consistent with poll(2) 313 * polling a closed fd. Hope this will remind 314 * user to do a POLLREMOVE. 315 */ 316 pfdp[fdcnt].fd = fd; 317 pfdp[fdcnt].revents = POLLNVAL; 318 fdcnt++; 319 continue; 320 } 321 if (fp != pdp->pd_fp) { 322 /* 323 * user is polling on a cached fd which was 324 * closed and then reused. Unfortunately 325 * there is no good way to inform user. 326 * If the file struct is also reused, we 327 * may not be able to detect the fd reuse 328 * at all. As long as this does not 329 * cause system failure and/or memory leak, 330 * we will play along. Man page states if 331 * user does not clean up closed fds, polling 332 * results will be indeterministic. 333 * 334 * XXX - perhaps log the detection of fd 335 * reuse? 336 */ 337 pdp->pd_fp = fp; 338 } 339 /* 340 * XXX - pollrelock() logic needs to know which 341 * which pollcache lock to grab. It'd be a 342 * cleaner solution if we could pass pcp as 343 * an arguement in VOP_POLL interface instead 344 * of implicitly passing it using thread_t 345 * struct. On the other hand, changing VOP_POLL 346 * interface will require all driver/file system 347 * poll routine to change. May want to revisit 348 * the tradeoff later. 349 */ 350 curthread->t_pollcache = pcp; 351 error = VOP_POLL(fp->f_vnode, pdp->pd_events, 0, 352 &revent, &php, NULL); 353 curthread->t_pollcache = NULL; 354 releasef(fd); 355 if (error != 0) { 356 break; 357 } 358 /* 359 * layered devices (e.g. console driver) 360 * may change the vnode and thus the pollhead 361 * pointer out from underneath us. 362 */ 363 if (php != NULL && pdp->pd_php != NULL && 364 php != pdp->pd_php) { 365 pollhead_delete(pdp->pd_php, pdp); 366 pdp->pd_php = php; 367 pollhead_insert(php, pdp); 368 /* 369 * The bit should still be set. 370 */ 371 ASSERT(BT_TEST(pcp->pc_bitmap, fd)); 372 goto retry; 373 } 374 375 if (revent != 0) { 376 pfdp[fdcnt].fd = fd; 377 pfdp[fdcnt].events = pdp->pd_events; 378 pfdp[fdcnt].revents = revent; 379 fdcnt++; 380 } else if (php != NULL) { 381 /* 382 * We clear a bit or cache a poll fd if 383 * the driver returns a poll head ptr, 384 * which is expected in the case of 0 385 * revents. Some buggy driver may return 386 * NULL php pointer with 0 revents. In 387 * this case, we just treat the driver as 388 * "noncachable" and not clearing the bit 389 * in bitmap. 390 */ 391 if ((pdp->pd_php != NULL) && 392 ((pcp->pc_flag & T_POLLWAKE) == 0)) { 393 BT_CLEAR(pcp->pc_bitmap, fd); 394 } 395 if (pdp->pd_php == NULL) { 396 pollhead_insert(php, pdp); 397 pdp->pd_php = php; 398 /* 399 * An event of interest may have 400 * arrived between the VOP_POLL() and 401 * the pollhead_insert(); check again. 402 */ 403 goto repoll; 404 } 405 } 406 } else { 407 /* 408 * No bit set in the range. Check for wrap around. 409 */ 410 if (!no_wrap) { 411 start = 0; 412 end = ostart - 1; 413 no_wrap = B_TRUE; 414 } else { 415 done = B_TRUE; 416 } 417 } 418 } 419 420 if (!done) { 421 pcp->pc_mapstart = start; 422 } 423 ASSERT(*fdcntp == 0); 424 *fdcntp = fdcnt; 425 return (error); 426 } 427 428 /*ARGSUSED*/ 429 static int 430 dpopen(dev_t *devp, int flag, int otyp, cred_t *credp) 431 { 432 minor_t minordev; 433 dp_entry_t *dpep; 434 pollcache_t *pcp; 435 436 ASSERT(devpoll_init); 437 ASSERT(dptblsize <= MAXMIN); 438 mutex_enter(&devpoll_lock); 439 for (minordev = 0; minordev < dptblsize; minordev++) { 440 if (devpolltbl[minordev] == NULL) { 441 devpolltbl[minordev] = (dp_entry_t *)RESERVED; 442 break; 443 } 444 } 445 if (minordev == dptblsize) { 446 dp_entry_t **newtbl; 447 size_t oldsize; 448 449 /* 450 * Used up every entry in the existing devpoll table. 451 * Grow the table by DEVPOLLSIZE. 452 */ 453 if ((oldsize = dptblsize) >= MAXMIN) { 454 mutex_exit(&devpoll_lock); 455 return (ENXIO); 456 } 457 dptblsize += DEVPOLLSIZE; 458 if (dptblsize > MAXMIN) { 459 dptblsize = MAXMIN; 460 } 461 newtbl = kmem_zalloc(sizeof (caddr_t) * dptblsize, KM_SLEEP); 462 bcopy(devpolltbl, newtbl, sizeof (caddr_t) * oldsize); 463 kmem_free(devpolltbl, sizeof (caddr_t) * oldsize); 464 devpolltbl = newtbl; 465 devpolltbl[minordev] = (dp_entry_t *)RESERVED; 466 } 467 mutex_exit(&devpoll_lock); 468 469 dpep = kmem_zalloc(sizeof (dp_entry_t), KM_SLEEP); 470 /* 471 * allocate a pollcache skeleton here. Delay allocating bitmap 472 * structures until dpwrite() time, since we don't know the 473 * optimal size yet. 474 */ 475 pcp = pcache_alloc(); 476 dpep->dpe_pcache = pcp; 477 pcp->pc_pid = curproc->p_pid; 478 *devp = makedevice(getmajor(*devp), minordev); /* clone the driver */ 479 mutex_enter(&devpoll_lock); 480 ASSERT(minordev < dptblsize); 481 ASSERT(devpolltbl[minordev] == (dp_entry_t *)RESERVED); 482 devpolltbl[minordev] = dpep; 483 mutex_exit(&devpoll_lock); 484 return (0); 485 } 486 487 /* 488 * Write to dev/poll add/remove fd's to/from a cached poll fd set, 489 * or change poll events for a watched fd. 490 */ 491 /*ARGSUSED*/ 492 static int 493 dpwrite(dev_t dev, struct uio *uiop, cred_t *credp) 494 { 495 minor_t minor; 496 dp_entry_t *dpep; 497 pollcache_t *pcp; 498 pollfd_t *pollfdp, *pfdp; 499 int error; 500 ssize_t uiosize; 501 nfds_t pollfdnum; 502 struct pollhead *php = NULL; 503 polldat_t *pdp; 504 int fd; 505 file_t *fp; 506 507 minor = getminor(dev); 508 509 mutex_enter(&devpoll_lock); 510 ASSERT(minor < dptblsize); 511 dpep = devpolltbl[minor]; 512 ASSERT(dpep != NULL); 513 mutex_exit(&devpoll_lock); 514 pcp = dpep->dpe_pcache; 515 if (curproc->p_pid != pcp->pc_pid) { 516 return (EACCES); 517 } 518 uiosize = uiop->uio_resid; 519 pollfdnum = uiosize / sizeof (pollfd_t); 520 mutex_enter(&curproc->p_lock); 521 if (pollfdnum > (uint_t)rctl_enforced_value( 522 rctlproc_legacy[RLIMIT_NOFILE], curproc->p_rctls, curproc)) { 523 (void) rctl_action(rctlproc_legacy[RLIMIT_NOFILE], 524 curproc->p_rctls, curproc, RCA_SAFE); 525 mutex_exit(&curproc->p_lock); 526 return (set_errno(EINVAL)); 527 } 528 mutex_exit(&curproc->p_lock); 529 /* 530 * Copy in the pollfd array. Walk through the array and add 531 * each polled fd to the cached set. 532 */ 533 pollfdp = kmem_alloc(uiosize, KM_SLEEP); 534 535 /* 536 * Although /dev/poll uses the write(2) interface to cache fds, it's 537 * not supposed to function as a seekable device. To prevent offset 538 * from growing and eventually exceed the maximum, reset the offset 539 * here for every call. 540 */ 541 uiop->uio_loffset = 0; 542 if ((error = uiomove((caddr_t)pollfdp, uiosize, UIO_WRITE, uiop)) 543 != 0) { 544 kmem_free(pollfdp, uiosize); 545 return (error); 546 } 547 /* 548 * We are about to enter the core portion of dpwrite(). Make sure this 549 * write has exclusive access in this portion of the code, i.e., no 550 * other writers in this code and no other readers in dpioctl. 551 */ 552 mutex_enter(&dpep->dpe_lock); 553 dpep->dpe_writerwait++; 554 while (dpep->dpe_refcnt != 0) { 555 if (!cv_wait_sig_swap(&dpep->dpe_cv, &dpep->dpe_lock)) { 556 dpep->dpe_writerwait--; 557 mutex_exit(&dpep->dpe_lock); 558 kmem_free(pollfdp, uiosize); 559 return (set_errno(EINTR)); 560 } 561 } 562 dpep->dpe_writerwait--; 563 dpep->dpe_flag |= DP_WRITER_PRESENT; 564 dpep->dpe_refcnt++; 565 mutex_exit(&dpep->dpe_lock); 566 567 mutex_enter(&pcp->pc_lock); 568 if (pcp->pc_bitmap == NULL) { 569 pcache_create(pcp, pollfdnum); 570 } 571 for (pfdp = pollfdp; pfdp < pollfdp + pollfdnum; pfdp++) { 572 fd = pfdp->fd; 573 if ((uint_t)fd >= P_FINFO(curproc)->fi_nfiles) 574 continue; 575 pdp = pcache_lookup_fd(pcp, fd); 576 if (pfdp->events != POLLREMOVE) { 577 if (pdp == NULL) { 578 pdp = pcache_alloc_fd(0); 579 pdp->pd_fd = fd; 580 pdp->pd_pcache = pcp; 581 pcache_insert_fd(pcp, pdp, pollfdnum); 582 } 583 ASSERT(pdp->pd_fd == fd); 584 ASSERT(pdp->pd_pcache == pcp); 585 if (fd >= pcp->pc_mapsize) { 586 mutex_exit(&pcp->pc_lock); 587 pcache_grow_map(pcp, fd); 588 mutex_enter(&pcp->pc_lock); 589 } 590 if (fd > pcp->pc_mapend) { 591 pcp->pc_mapend = fd; 592 } 593 if ((fp = getf(fd)) == NULL) { 594 /* 595 * The fd is not valid. Since we can't pass 596 * this error back in the write() call, set 597 * the bit in bitmap to force DP_POLL ioctl 598 * to examine it. 599 */ 600 BT_SET(pcp->pc_bitmap, fd); 601 pdp->pd_events |= pfdp->events; 602 continue; 603 } 604 /* 605 * Don't do VOP_POLL for an already cached fd with 606 * same poll events. 607 */ 608 if ((pdp->pd_events == pfdp->events) && 609 (pdp->pd_fp != NULL)) { 610 /* 611 * the events are already cached 612 */ 613 releasef(fd); 614 continue; 615 } 616 617 /* 618 * do VOP_POLL and cache this poll fd. 619 */ 620 /* 621 * XXX - pollrelock() logic needs to know which 622 * which pollcache lock to grab. It'd be a 623 * cleaner solution if we could pass pcp as 624 * an arguement in VOP_POLL interface instead 625 * of implicitly passing it using thread_t 626 * struct. On the other hand, changing VOP_POLL 627 * interface will require all driver/file system 628 * poll routine to change. May want to revisit 629 * the tradeoff later. 630 */ 631 curthread->t_pollcache = pcp; 632 error = VOP_POLL(fp->f_vnode, pfdp->events, 0, 633 &pfdp->revents, &php, NULL); 634 curthread->t_pollcache = NULL; 635 /* 636 * We always set the bit when this fd is cached; 637 * this forces the first DP_POLL to poll this fd. 638 * Real performance gain comes from subsequent 639 * DP_POLL. We also attempt a pollhead_insert(); 640 * if it's not possible, we'll do it in dpioctl(). 641 */ 642 BT_SET(pcp->pc_bitmap, fd); 643 if (error != 0) { 644 releasef(fd); 645 break; 646 } 647 pdp->pd_fp = fp; 648 pdp->pd_events |= pfdp->events; 649 if (php != NULL) { 650 if (pdp->pd_php == NULL) { 651 pollhead_insert(php, pdp); 652 pdp->pd_php = php; 653 } else { 654 if (pdp->pd_php != php) { 655 pollhead_delete(pdp->pd_php, 656 pdp); 657 pollhead_insert(php, pdp); 658 pdp->pd_php = php; 659 } 660 } 661 662 } 663 releasef(fd); 664 } else { 665 if (pdp == NULL) { 666 continue; 667 } 668 ASSERT(pdp->pd_fd == fd); 669 pdp->pd_fp = NULL; 670 pdp->pd_events = 0; 671 ASSERT(pdp->pd_thread == NULL); 672 if (pdp->pd_php != NULL) { 673 pollhead_delete(pdp->pd_php, pdp); 674 pdp->pd_php = NULL; 675 } 676 BT_CLEAR(pcp->pc_bitmap, fd); 677 } 678 } 679 mutex_exit(&pcp->pc_lock); 680 mutex_enter(&dpep->dpe_lock); 681 dpep->dpe_flag &= ~DP_WRITER_PRESENT; 682 ASSERT(dpep->dpe_refcnt == 1); 683 dpep->dpe_refcnt--; 684 cv_broadcast(&dpep->dpe_cv); 685 mutex_exit(&dpep->dpe_lock); 686 kmem_free(pollfdp, uiosize); 687 return (error); 688 } 689 690 /*ARGSUSED*/ 691 static int 692 dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp) 693 { 694 timestruc_t now; 695 timestruc_t rqtime; 696 timestruc_t *rqtp = NULL; 697 int timecheck = 0; 698 minor_t minor; 699 dp_entry_t *dpep; 700 pollcache_t *pcp; 701 int error = 0; 702 STRUCT_DECL(dvpoll, dvpoll); 703 704 if (cmd == DP_POLL) { 705 /* do this now, before we sleep on DP_WRITER_PRESENT below */ 706 timecheck = timechanged; 707 gethrestime(&now); 708 } 709 minor = getminor(dev); 710 mutex_enter(&devpoll_lock); 711 ASSERT(minor < dptblsize); 712 dpep = devpolltbl[minor]; 713 mutex_exit(&devpoll_lock); 714 ASSERT(dpep != NULL); 715 pcp = dpep->dpe_pcache; 716 if (curproc->p_pid != pcp->pc_pid) 717 return (EACCES); 718 719 mutex_enter(&dpep->dpe_lock); 720 while ((dpep->dpe_flag & DP_WRITER_PRESENT) || 721 (dpep->dpe_writerwait != 0)) { 722 if (!cv_wait_sig_swap(&dpep->dpe_cv, &dpep->dpe_lock)) { 723 mutex_exit(&dpep->dpe_lock); 724 return (EINTR); 725 } 726 } 727 dpep->dpe_refcnt++; 728 mutex_exit(&dpep->dpe_lock); 729 730 switch (cmd) { 731 case DP_POLL: 732 { 733 pollstate_t *ps; 734 nfds_t nfds; 735 int fdcnt = 0; 736 int time_out; 737 int rval; 738 739 STRUCT_INIT(dvpoll, mode); 740 error = copyin((caddr_t)arg, STRUCT_BUF(dvpoll), 741 STRUCT_SIZE(dvpoll)); 742 if (error) { 743 DP_REFRELE(dpep); 744 return (EFAULT); 745 } 746 747 time_out = STRUCT_FGET(dvpoll, dp_timeout); 748 if (time_out > 0) { 749 /* 750 * Determine the future time of the requested timeout. 751 */ 752 rqtp = &rqtime; 753 rqtp->tv_sec = time_out / MILLISEC; 754 rqtp->tv_nsec = (time_out % MILLISEC) * MICROSEC; 755 timespecadd(rqtp, &now); 756 } 757 758 if ((nfds = STRUCT_FGET(dvpoll, dp_nfds)) == 0) { 759 /* 760 * We are just using DP_POLL to sleep, so 761 * we don't any of the devpoll apparatus. 762 * Do not check for signals if we have a zero timeout. 763 */ 764 DP_REFRELE(dpep); 765 if (time_out == 0) 766 return (0); 767 mutex_enter(&curthread->t_delay_lock); 768 while ((rval = cv_waituntil_sig(&curthread->t_delay_cv, 769 &curthread->t_delay_lock, rqtp, timecheck)) > 0) 770 continue; 771 mutex_exit(&curthread->t_delay_lock); 772 return ((rval == 0)? EINTR : 0); 773 } 774 775 /* 776 * XXX It'd be nice not to have to alloc each time. 777 * But it requires another per thread structure hook. 778 * Do it later if there is data suggest that. 779 */ 780 if ((ps = curthread->t_pollstate) == NULL) { 781 curthread->t_pollstate = pollstate_create(); 782 ps = curthread->t_pollstate; 783 } 784 if (ps->ps_dpbufsize < nfds) { 785 struct proc *p = ttoproc(curthread); 786 /* 787 * The maximum size should be no large than 788 * current maximum open file count. 789 */ 790 mutex_enter(&p->p_lock); 791 if (nfds > p->p_fno_ctl) { 792 mutex_exit(&p->p_lock); 793 DP_REFRELE(dpep); 794 return (EINVAL); 795 } 796 mutex_exit(&p->p_lock); 797 kmem_free(ps->ps_dpbuf, sizeof (pollfd_t) * 798 ps->ps_dpbufsize); 799 ps->ps_dpbuf = kmem_zalloc(sizeof (pollfd_t) * 800 nfds, KM_SLEEP); 801 ps->ps_dpbufsize = nfds; 802 } 803 804 mutex_enter(&pcp->pc_lock); 805 for (;;) { 806 pcp->pc_flag = 0; 807 error = dp_pcache_poll(ps->ps_dpbuf, pcp, nfds, &fdcnt); 808 if (fdcnt > 0 || error != 0) 809 break; 810 811 /* 812 * A pollwake has happened since we polled cache. 813 */ 814 if (pcp->pc_flag & T_POLLWAKE) 815 continue; 816 817 /* 818 * Sleep until we are notified, signaled, or timed out. 819 * Do not check for signals if we have a zero timeout. 820 */ 821 if (time_out == 0) /* immediate timeout */ 822 break; 823 rval = cv_waituntil_sig(&pcp->pc_cv, &pcp->pc_lock, 824 rqtp, timecheck); 825 /* 826 * If we were awakened by a signal or timeout 827 * then break the loop, else poll again. 828 */ 829 if (rval <= 0) { 830 if (rval == 0) /* signal */ 831 error = EINTR; 832 break; 833 } 834 } 835 mutex_exit(&pcp->pc_lock); 836 837 if (error == 0 && fdcnt > 0) { 838 if (copyout(ps->ps_dpbuf, STRUCT_FGETP(dvpoll, 839 dp_fds), sizeof (pollfd_t) * fdcnt)) { 840 DP_REFRELE(dpep); 841 return (EFAULT); 842 } 843 *rvalp = fdcnt; 844 } 845 break; 846 } 847 848 case DP_ISPOLLED: 849 { 850 pollfd_t pollfd; 851 polldat_t *pdp; 852 853 STRUCT_INIT(dvpoll, mode); 854 error = copyin((caddr_t)arg, &pollfd, sizeof (pollfd_t)); 855 if (error) { 856 DP_REFRELE(dpep); 857 return (EFAULT); 858 } 859 mutex_enter(&pcp->pc_lock); 860 if (pcp->pc_hash == NULL) { 861 /* 862 * No Need to search because no poll fd 863 * has been cached. 864 */ 865 mutex_exit(&pcp->pc_lock); 866 DP_REFRELE(dpep); 867 return (0); 868 } 869 if (pollfd.fd < 0) { 870 mutex_exit(&pcp->pc_lock); 871 break; 872 } 873 pdp = pcache_lookup_fd(pcp, pollfd.fd); 874 if ((pdp != NULL) && (pdp->pd_fd == pollfd.fd) && 875 (pdp->pd_fp != NULL)) { 876 pollfd.revents = pdp->pd_events; 877 if (copyout(&pollfd, (caddr_t)arg, sizeof (pollfd_t))) { 878 mutex_exit(&pcp->pc_lock); 879 DP_REFRELE(dpep); 880 return (EFAULT); 881 } 882 *rvalp = 1; 883 } 884 mutex_exit(&pcp->pc_lock); 885 break; 886 } 887 888 default: 889 DP_REFRELE(dpep); 890 return (EINVAL); 891 } 892 DP_REFRELE(dpep); 893 return (error); 894 } 895 896 /*ARGSUSED*/ 897 static int 898 dppoll(dev_t dev, short events, int anyyet, short *reventsp, 899 struct pollhead **phpp) 900 { 901 /* 902 * Polling on a /dev/poll fd is not fully supported yet. 903 */ 904 *reventsp = POLLERR; 905 return (0); 906 } 907 908 /* 909 * devpoll close should do enough clean up before the pollcache is deleted, 910 * i.e., it should ensure no one still references the pollcache later. 911 * There is no "permission" check in here. Any process having the last 912 * reference of this /dev/poll fd can close. 913 */ 914 /*ARGSUSED*/ 915 static int 916 dpclose(dev_t dev, int flag, int otyp, cred_t *credp) 917 { 918 minor_t minor; 919 dp_entry_t *dpep; 920 pollcache_t *pcp; 921 int i; 922 polldat_t **hashtbl; 923 polldat_t *pdp; 924 925 minor = getminor(dev); 926 927 mutex_enter(&devpoll_lock); 928 dpep = devpolltbl[minor]; 929 ASSERT(dpep != NULL); 930 devpolltbl[minor] = NULL; 931 mutex_exit(&devpoll_lock); 932 pcp = dpep->dpe_pcache; 933 ASSERT(pcp != NULL); 934 /* 935 * At this point, no other lwp can access this pollcache via the 936 * /dev/poll fd. This pollcache is going away, so do the clean 937 * up without the pc_lock. 938 */ 939 hashtbl = pcp->pc_hash; 940 for (i = 0; i < pcp->pc_hashsize; i++) { 941 for (pdp = hashtbl[i]; pdp; pdp = pdp->pd_hashnext) { 942 if (pdp->pd_php != NULL) { 943 pollhead_delete(pdp->pd_php, pdp); 944 pdp->pd_php = NULL; 945 pdp->pd_fp = NULL; 946 } 947 } 948 } 949 /* 950 * pollwakeup() may still interact with this pollcache. Wait until 951 * it is done. 952 */ 953 mutex_enter(&pcp->pc_no_exit); 954 ASSERT(pcp->pc_busy >= 0); 955 while (pcp->pc_busy > 0) 956 cv_wait(&pcp->pc_busy_cv, &pcp->pc_no_exit); 957 mutex_exit(&pcp->pc_no_exit); 958 pcache_destroy(pcp); 959 ASSERT(dpep->dpe_refcnt == 0); 960 kmem_free(dpep, sizeof (dp_entry_t)); 961 return (0); 962 }
Cache object: e0311836f221f8b13c8a1fddf295cefd
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