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 * Copyright (c) 2012 by Delphix. All rights reserved.
28 */
29
30 #include <sys/types.h>
31 #include <sys/devops.h>
32 #include <sys/conf.h>
33 #include <sys/modctl.h>
34 #include <sys/sunddi.h>
35 #include <sys/stat.h>
36 #include <sys/poll_impl.h>
37 #include <sys/errno.h>
38 #include <sys/kmem.h>
39 #include <sys/mkdev.h>
40 #include <sys/debug.h>
41 #include <sys/file.h>
42 #include <sys/sysmacros.h>
43 #include <sys/systm.h>
44 #include <sys/bitmap.h>
45 #include <sys/devpoll.h>
46 #include <sys/rctl.h>
47 #include <sys/resource.h>
48
49 #define RESERVED 1
50
51 /* local data struct */
52 static dp_entry_t **devpolltbl; /* dev poll entries */
53 static size_t dptblsize;
54
55 static kmutex_t devpoll_lock; /* lock protecting dev tbl */
56 int devpoll_init; /* is /dev/poll initialized already */
57
58 /* device local functions */
59
60 static int dpopen(dev_t *devp, int flag, int otyp, cred_t *credp);
61 static int dpwrite(dev_t dev, struct uio *uiop, cred_t *credp);
62 static int dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp,
63 int *rvalp);
64 static int dppoll(dev_t dev, short events, int anyyet, short *reventsp,
65 struct pollhead **phpp);
66 static int dpclose(dev_t dev, int flag, int otyp, cred_t *credp);
67 static dev_info_t *dpdevi;
68
69
70 static struct cb_ops dp_cb_ops = {
71 dpopen, /* open */
72 dpclose, /* close */
73 nodev, /* strategy */
74 nodev, /* print */
75 nodev, /* dump */
76 nodev, /* read */
77 dpwrite, /* write */
78 dpioctl, /* ioctl */
79 nodev, /* devmap */
80 nodev, /* mmap */
81 nodev, /* segmap */
82 dppoll, /* poll */
83 ddi_prop_op, /* prop_op */
84 (struct streamtab *)0, /* streamtab */
85 D_MP, /* flags */
86 CB_REV, /* cb_ops revision */
87 nodev, /* aread */
88 nodev /* awrite */
89 };
90
91 static int dpattach(dev_info_t *, ddi_attach_cmd_t);
92 static int dpdetach(dev_info_t *, ddi_detach_cmd_t);
93 static int dpinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
94
95 static struct dev_ops dp_ops = {
96 DEVO_REV, /* devo_rev */
97 0, /* refcnt */
98 dpinfo, /* info */
99 nulldev, /* identify */
100 nulldev, /* probe */
101 dpattach, /* attach */
102 dpdetach, /* detach */
103 nodev, /* reset */
104 &dp_cb_ops, /* driver operations */
105 (struct bus_ops *)NULL, /* bus operations */
106 nulldev, /* power */
107 ddi_quiesce_not_needed, /* quiesce */
108 };
109
110
111 static struct modldrv modldrv = {
112 &mod_driverops, /* type of module - a driver */
113 "/dev/poll driver",
114 &dp_ops,
115 };
116
117 static struct modlinkage modlinkage = {
118 MODREV_1,
119 (void *)&modldrv,
120 NULL
121 };
122
123 /*
124 * Locking Design
125 *
126 * The /dev/poll driver shares most of its code with poll sys call whose
127 * code is in common/syscall/poll.c. In poll(2) design, the pollcache
128 * structure is per lwp. An implicit assumption is made there that some
129 * portion of pollcache will never be touched by other lwps. E.g., in
130 * poll(2) design, no lwp will ever need to grow bitmap of other lwp.
131 * This assumption is not true for /dev/poll; hence the need for extra
132 * locking.
133 *
134 * To allow more parallelism, each /dev/poll file descriptor (indexed by
135 * minor number) has its own lock. Since read (dpioctl) is a much more
136 * frequent operation than write, we want to allow multiple reads on same
137 * /dev/poll fd. However, we prevent writes from being starved by giving
138 * priority to write operation. Theoretically writes can starve reads as
139 * well. But in practical sense this is not important because (1) writes
140 * happens less often than reads, and (2) write operation defines the
141 * content of poll fd a cache set. If writes happens so often that they
142 * can starve reads, that means the cached set is very unstable. It may
143 * not make sense to read an unstable cache set anyway. Therefore, the
144 * writers starving readers case is not handled in this design.
145 */
146
147 int
148 _init()
149 {
150 int error;
151
152 dptblsize = DEVPOLLSIZE;
153 devpolltbl = kmem_zalloc(sizeof (caddr_t) * dptblsize, KM_SLEEP);
154 mutex_init(&devpoll_lock, NULL, MUTEX_DEFAULT, NULL);
155 devpoll_init = 1;
156 if ((error = mod_install(&modlinkage)) != 0) {
157 mutex_destroy(&devpoll_lock);
158 kmem_free(devpolltbl, sizeof (caddr_t) * dptblsize);
159 devpoll_init = 0;
160 }
161 return (error);
162 }
163
164 int
165 _fini()
166 {
167 int error;
168
169 if ((error = mod_remove(&modlinkage)) != 0) {
170 return (error);
171 }
172 mutex_destroy(&devpoll_lock);
173 kmem_free(devpolltbl, sizeof (caddr_t) * dptblsize);
174 return (0);
175 }
176
177 int
178 _info(struct modinfo *modinfop)
179 {
180 return (mod_info(&modlinkage, modinfop));
181 }
182
183 /*ARGSUSED*/
184 static int
185 dpattach(dev_info_t *devi, ddi_attach_cmd_t cmd)
186 {
187 if (ddi_create_minor_node(devi, "poll", S_IFCHR, 0, DDI_PSEUDO, NULL)
188 == DDI_FAILURE) {
189 ddi_remove_minor_node(devi, NULL);
190 return (DDI_FAILURE);
191 }
192 dpdevi = devi;
193 return (DDI_SUCCESS);
194 }
195
196 static int
197 dpdetach(dev_info_t *devi, ddi_detach_cmd_t cmd)
198 {
199 if (cmd != DDI_DETACH)
200 return (DDI_FAILURE);
201
202 ddi_remove_minor_node(devi, NULL);
203 return (DDI_SUCCESS);
204 }
205
206 /* ARGSUSED */
207 static int
208 dpinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
209 {
210 int error;
211
212 switch (infocmd) {
213 case DDI_INFO_DEVT2DEVINFO:
214 *result = (void *)dpdevi;
215 error = DDI_SUCCESS;
216 break;
217 case DDI_INFO_DEVT2INSTANCE:
218 *result = (void *)0;
219 error = DDI_SUCCESS;
220 break;
221 default:
222 error = DDI_FAILURE;
223 }
224 return (error);
225 }
226
227 /*
228 * dp_pcache_poll has similar logic to pcache_poll() in poll.c. The major
229 * differences are: (1) /dev/poll requires scanning the bitmap starting at
230 * where it was stopped last time, instead of always starting from 0,
231 * (2) since user may not have cleaned up the cached fds when they are
232 * closed, some polldats in cache may refer to closed or reused fds. We
233 * need to check for those cases.
234 *
235 * NOTE: Upon closing an fd, automatic poll cache cleanup is done for
236 * poll(2) caches but NOT for /dev/poll caches. So expect some
237 * stale entries!
238 */
239 static int
240 dp_pcache_poll(pollfd_t *pfdp, pollcache_t *pcp, nfds_t nfds, int *fdcntp)
241 {
242 int start, ostart, end;
243 int fdcnt, fd;
244 boolean_t done;
245 file_t *fp;
246 short revent;
247 boolean_t no_wrap;
248 pollhead_t *php;
249 polldat_t *pdp;
250 int error = 0;
251
252 ASSERT(MUTEX_HELD(&pcp->pc_lock));
253 if (pcp->pc_bitmap == NULL) {
254 /*
255 * No Need to search because no poll fd
256 * has been cached.
257 */
258 return (error);
259 }
260 retry:
261 start = ostart = pcp->pc_mapstart;
262 end = pcp->pc_mapend;
263 php = NULL;
264
265 if (start == 0) {
266 /*
267 * started from every begining, no need to wrap around.
268 */
269 no_wrap = B_TRUE;
270 } else {
271 no_wrap = B_FALSE;
272 }
273 done = B_FALSE;
274 fdcnt = 0;
275 while ((fdcnt < nfds) && !done) {
276 php = NULL;
277 revent = 0;
278 /*
279 * Examine the bit map in a circular fashion
280 * to avoid starvation. Always resume from
281 * last stop. Scan till end of the map. Then
282 * wrap around.
283 */
284 fd = bt_getlowbit(pcp->pc_bitmap, start, end);
285 ASSERT(fd <= end);
286 if (fd >= 0) {
287 if (fd == end) {
288 if (no_wrap) {
289 done = B_TRUE;
290 } else {
291 start = 0;
292 end = ostart - 1;
293 no_wrap = B_TRUE;
294 }
295 } else {
296 start = fd + 1;
297 }
298 pdp = pcache_lookup_fd(pcp, fd);
299 repoll:
300 ASSERT(pdp != NULL);
301 ASSERT(pdp->pd_fd == fd);
302 if (pdp->pd_fp == NULL) {
303 /*
304 * The fd is POLLREMOVed. This fd is
305 * logically no longer cached. So move
306 * on to the next one.
307 */
308 continue;
309 }
310 if ((fp = getf(fd)) == NULL) {
311 /*
312 * The fd has been closed, but user has not
313 * done a POLLREMOVE on this fd yet. Instead
314 * of cleaning it here implicitly, we return
315 * POLLNVAL. This is consistent with poll(2)
316 * polling a closed fd. Hope this will remind
317 * user to do a POLLREMOVE.
318 */
319 pfdp[fdcnt].fd = fd;
320 pfdp[fdcnt].revents = POLLNVAL;
321 fdcnt++;
322 continue;
323 }
324 if (fp != pdp->pd_fp) {
325 /*
326 * user is polling on a cached fd which was
327 * closed and then reused. Unfortunately
328 * there is no good way to inform user.
329 * If the file struct is also reused, we
330 * may not be able to detect the fd reuse
331 * at all. As long as this does not
332 * cause system failure and/or memory leak,
333 * we will play along. Man page states if
334 * user does not clean up closed fds, polling
335 * results will be indeterministic.
336 *
337 * XXX - perhaps log the detection of fd
338 * reuse?
339 */
340 pdp->pd_fp = fp;
341 }
342 /*
343 * XXX - pollrelock() logic needs to know which
344 * which pollcache lock to grab. It'd be a
345 * cleaner solution if we could pass pcp as
346 * an arguement in VOP_POLL interface instead
347 * of implicitly passing it using thread_t
348 * struct. On the other hand, changing VOP_POLL
349 * interface will require all driver/file system
350 * poll routine to change. May want to revisit
351 * the tradeoff later.
352 */
353 curthread->t_pollcache = pcp;
354 error = VOP_POLL(fp->f_vnode, pdp->pd_events, 0,
355 &revent, &php, NULL);
356 curthread->t_pollcache = NULL;
357 releasef(fd);
358 if (error != 0) {
359 break;
360 }
361 /*
362 * layered devices (e.g. console driver)
363 * may change the vnode and thus the pollhead
364 * pointer out from underneath us.
365 */
366 if (php != NULL && pdp->pd_php != NULL &&
367 php != pdp->pd_php) {
368 pollhead_delete(pdp->pd_php, pdp);
369 pdp->pd_php = php;
370 pollhead_insert(php, pdp);
371 /*
372 * The bit should still be set.
373 */
374 ASSERT(BT_TEST(pcp->pc_bitmap, fd));
375 goto retry;
376 }
377
378 if (revent != 0) {
379 pfdp[fdcnt].fd = fd;
380 pfdp[fdcnt].events = pdp->pd_events;
381 pfdp[fdcnt].revents = revent;
382 fdcnt++;
383 } else if (php != NULL) {
384 /*
385 * We clear a bit or cache a poll fd if
386 * the driver returns a poll head ptr,
387 * which is expected in the case of 0
388 * revents. Some buggy driver may return
389 * NULL php pointer with 0 revents. In
390 * this case, we just treat the driver as
391 * "noncachable" and not clearing the bit
392 * in bitmap.
393 */
394 if ((pdp->pd_php != NULL) &&
395 ((pcp->pc_flag & T_POLLWAKE) == 0)) {
396 BT_CLEAR(pcp->pc_bitmap, fd);
397 }
398 if (pdp->pd_php == NULL) {
399 pollhead_insert(php, pdp);
400 pdp->pd_php = php;
401 /*
402 * An event of interest may have
403 * arrived between the VOP_POLL() and
404 * the pollhead_insert(); check again.
405 */
406 goto repoll;
407 }
408 }
409 } else {
410 /*
411 * No bit set in the range. Check for wrap around.
412 */
413 if (!no_wrap) {
414 start = 0;
415 end = ostart - 1;
416 no_wrap = B_TRUE;
417 } else {
418 done = B_TRUE;
419 }
420 }
421 }
422
423 if (!done) {
424 pcp->pc_mapstart = start;
425 }
426 ASSERT(*fdcntp == 0);
427 *fdcntp = fdcnt;
428 return (error);
429 }
430
431 /*ARGSUSED*/
432 static int
433 dpopen(dev_t *devp, int flag, int otyp, cred_t *credp)
434 {
435 minor_t minordev;
436 dp_entry_t *dpep;
437 pollcache_t *pcp;
438
439 ASSERT(devpoll_init);
440 ASSERT(dptblsize <= MAXMIN);
441 mutex_enter(&devpoll_lock);
442 for (minordev = 0; minordev < dptblsize; minordev++) {
443 if (devpolltbl[minordev] == NULL) {
444 devpolltbl[minordev] = (dp_entry_t *)RESERVED;
445 break;
446 }
447 }
448 if (minordev == dptblsize) {
449 dp_entry_t **newtbl;
450 size_t oldsize;
451
452 /*
453 * Used up every entry in the existing devpoll table.
454 * Grow the table by DEVPOLLSIZE.
455 */
456 if ((oldsize = dptblsize) >= MAXMIN) {
457 mutex_exit(&devpoll_lock);
458 return (ENXIO);
459 }
460 dptblsize += DEVPOLLSIZE;
461 if (dptblsize > MAXMIN) {
462 dptblsize = MAXMIN;
463 }
464 newtbl = kmem_zalloc(sizeof (caddr_t) * dptblsize, KM_SLEEP);
465 bcopy(devpolltbl, newtbl, sizeof (caddr_t) * oldsize);
466 kmem_free(devpolltbl, sizeof (caddr_t) * oldsize);
467 devpolltbl = newtbl;
468 devpolltbl[minordev] = (dp_entry_t *)RESERVED;
469 }
470 mutex_exit(&devpoll_lock);
471
472 dpep = kmem_zalloc(sizeof (dp_entry_t), KM_SLEEP);
473 /*
474 * allocate a pollcache skeleton here. Delay allocating bitmap
475 * structures until dpwrite() time, since we don't know the
476 * optimal size yet.
477 */
478 pcp = pcache_alloc();
479 dpep->dpe_pcache = pcp;
480 pcp->pc_pid = curproc->p_pid;
481 *devp = makedevice(getmajor(*devp), minordev); /* clone the driver */
482 mutex_enter(&devpoll_lock);
483 ASSERT(minordev < dptblsize);
484 ASSERT(devpolltbl[minordev] == (dp_entry_t *)RESERVED);
485 devpolltbl[minordev] = dpep;
486 mutex_exit(&devpoll_lock);
487 return (0);
488 }
489
490 /*
491 * Write to dev/poll add/remove fd's to/from a cached poll fd set,
492 * or change poll events for a watched fd.
493 */
494 /*ARGSUSED*/
495 static int
496 dpwrite(dev_t dev, struct uio *uiop, cred_t *credp)
497 {
498 minor_t minor;
499 dp_entry_t *dpep;
500 pollcache_t *pcp;
501 pollfd_t *pollfdp, *pfdp;
502 int error;
503 ssize_t uiosize;
504 nfds_t pollfdnum;
505 struct pollhead *php = NULL;
506 polldat_t *pdp;
507 int fd;
508 file_t *fp;
509
510 minor = getminor(dev);
511
512 mutex_enter(&devpoll_lock);
513 ASSERT(minor < dptblsize);
514 dpep = devpolltbl[minor];
515 ASSERT(dpep != NULL);
516 mutex_exit(&devpoll_lock);
517 pcp = dpep->dpe_pcache;
518 if (curproc->p_pid != pcp->pc_pid) {
519 return (EACCES);
520 }
521 uiosize = uiop->uio_resid;
522 pollfdnum = uiosize / sizeof (pollfd_t);
523 mutex_enter(&curproc->p_lock);
524 if (pollfdnum > (uint_t)rctl_enforced_value(
525 rctlproc_legacy[RLIMIT_NOFILE], curproc->p_rctls, curproc)) {
526 (void) rctl_action(rctlproc_legacy[RLIMIT_NOFILE],
527 curproc->p_rctls, curproc, RCA_SAFE);
528 mutex_exit(&curproc->p_lock);
529 return (set_errno(EINVAL));
530 }
531 mutex_exit(&curproc->p_lock);
532 /*
533 * Copy in the pollfd array. Walk through the array and add
534 * each polled fd to the cached set.
535 */
536 pollfdp = kmem_alloc(uiosize, KM_SLEEP);
537
538 /*
539 * Although /dev/poll uses the write(2) interface to cache fds, it's
540 * not supposed to function as a seekable device. To prevent offset
541 * from growing and eventually exceed the maximum, reset the offset
542 * here for every call.
543 */
544 uiop->uio_loffset = 0;
545 if ((error = uiomove((caddr_t)pollfdp, uiosize, UIO_WRITE, uiop))
546 != 0) {
547 kmem_free(pollfdp, uiosize);
548 return (error);
549 }
550 /*
551 * We are about to enter the core portion of dpwrite(). Make sure this
552 * write has exclusive access in this portion of the code, i.e., no
553 * other writers in this code and no other readers in dpioctl.
554 */
555 mutex_enter(&dpep->dpe_lock);
556 dpep->dpe_writerwait++;
557 while (dpep->dpe_refcnt != 0) {
558 if (!cv_wait_sig_swap(&dpep->dpe_cv, &dpep->dpe_lock)) {
559 dpep->dpe_writerwait--;
560 mutex_exit(&dpep->dpe_lock);
561 kmem_free(pollfdp, uiosize);
562 return (set_errno(EINTR));
563 }
564 }
565 dpep->dpe_writerwait--;
566 dpep->dpe_flag |= DP_WRITER_PRESENT;
567 dpep->dpe_refcnt++;
568 mutex_exit(&dpep->dpe_lock);
569
570 mutex_enter(&pcp->pc_lock);
571 if (pcp->pc_bitmap == NULL) {
572 pcache_create(pcp, pollfdnum);
573 }
574 for (pfdp = pollfdp; pfdp < pollfdp + pollfdnum; pfdp++) {
575 fd = pfdp->fd;
576 if ((uint_t)fd >= P_FINFO(curproc)->fi_nfiles)
577 continue;
578 pdp = pcache_lookup_fd(pcp, fd);
579 if (pfdp->events != POLLREMOVE) {
580 if (pdp == NULL) {
581 pdp = pcache_alloc_fd(0);
582 pdp->pd_fd = fd;
583 pdp->pd_pcache = pcp;
584 pcache_insert_fd(pcp, pdp, pollfdnum);
585 }
586 ASSERT(pdp->pd_fd == fd);
587 ASSERT(pdp->pd_pcache == pcp);
588 if (fd >= pcp->pc_mapsize) {
589 mutex_exit(&pcp->pc_lock);
590 pcache_grow_map(pcp, fd);
591 mutex_enter(&pcp->pc_lock);
592 }
593 if (fd > pcp->pc_mapend) {
594 pcp->pc_mapend = fd;
595 }
596 if ((fp = getf(fd)) == NULL) {
597 /*
598 * The fd is not valid. Since we can't pass
599 * this error back in the write() call, set
600 * the bit in bitmap to force DP_POLL ioctl
601 * to examine it.
602 */
603 BT_SET(pcp->pc_bitmap, fd);
604 pdp->pd_events |= pfdp->events;
605 continue;
606 }
607 /*
608 * Don't do VOP_POLL for an already cached fd with
609 * same poll events.
610 */
611 if ((pdp->pd_events == pfdp->events) &&
612 (pdp->pd_fp != NULL)) {
613 /*
614 * the events are already cached
615 */
616 releasef(fd);
617 continue;
618 }
619
620 /*
621 * do VOP_POLL and cache this poll fd.
622 */
623 /*
624 * XXX - pollrelock() logic needs to know which
625 * which pollcache lock to grab. It'd be a
626 * cleaner solution if we could pass pcp as
627 * an arguement in VOP_POLL interface instead
628 * of implicitly passing it using thread_t
629 * struct. On the other hand, changing VOP_POLL
630 * interface will require all driver/file system
631 * poll routine to change. May want to revisit
632 * the tradeoff later.
633 */
634 curthread->t_pollcache = pcp;
635 error = VOP_POLL(fp->f_vnode, pfdp->events, 0,
636 &pfdp->revents, &php, NULL);
637 curthread->t_pollcache = NULL;
638 /*
639 * We always set the bit when this fd is cached;
640 * this forces the first DP_POLL to poll this fd.
641 * Real performance gain comes from subsequent
642 * DP_POLL. We also attempt a pollhead_insert();
643 * if it's not possible, we'll do it in dpioctl().
644 */
645 BT_SET(pcp->pc_bitmap, fd);
646 if (error != 0) {
647 releasef(fd);
648 break;
649 }
650 pdp->pd_fp = fp;
651 pdp->pd_events |= pfdp->events;
652 if (php != NULL) {
653 if (pdp->pd_php == NULL) {
654 pollhead_insert(php, pdp);
655 pdp->pd_php = php;
656 } else {
657 if (pdp->pd_php != php) {
658 pollhead_delete(pdp->pd_php,
659 pdp);
660 pollhead_insert(php, pdp);
661 pdp->pd_php = php;
662 }
663 }
664
665 }
666 releasef(fd);
667 } else {
668 if (pdp == NULL) {
669 continue;
670 }
671 ASSERT(pdp->pd_fd == fd);
672 pdp->pd_fp = NULL;
673 pdp->pd_events = 0;
674 ASSERT(pdp->pd_thread == NULL);
675 if (pdp->pd_php != NULL) {
676 pollhead_delete(pdp->pd_php, pdp);
677 pdp->pd_php = NULL;
678 }
679 BT_CLEAR(pcp->pc_bitmap, fd);
680 }
681 }
682 mutex_exit(&pcp->pc_lock);
683 mutex_enter(&dpep->dpe_lock);
684 dpep->dpe_flag &= ~DP_WRITER_PRESENT;
685 ASSERT(dpep->dpe_refcnt == 1);
686 dpep->dpe_refcnt--;
687 cv_broadcast(&dpep->dpe_cv);
688 mutex_exit(&dpep->dpe_lock);
689 kmem_free(pollfdp, uiosize);
690 return (error);
691 }
692
693 /*ARGSUSED*/
694 static int
695 dpioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp, int *rvalp)
696 {
697 minor_t minor;
698 dp_entry_t *dpep;
699 pollcache_t *pcp;
700 hrtime_t now;
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 */
706 now = gethrtime();
707 }
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 hrtime_t deadline = 0;
737
738 STRUCT_INIT(dvpoll, mode);
739 error = copyin((caddr_t)arg, STRUCT_BUF(dvpoll),
740 STRUCT_SIZE(dvpoll));
741 if (error) {
742 DP_REFRELE(dpep);
743 return (EFAULT);
744 }
745
746 deadline = STRUCT_FGET(dvpoll, dp_timeout);
747 if (deadline > 0) {
748 /*
749 * Convert the deadline from relative milliseconds
750 * to absolute nanoseconds. They must wait for at
751 * least a tick.
752 */
753 deadline = deadline * NANOSEC / MILLISEC;
754 deadline = MAX(deadline, nsec_per_tick);
755 deadline += 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 (deadline == 0)
766 return (0);
767 mutex_enter(&curthread->t_delay_lock);
768 while ((error =
769 cv_timedwait_sig_hrtime(&curthread->t_delay_cv,
770 &curthread->t_delay_lock, deadline)) > 0)
771 continue;
772 mutex_exit(&curthread->t_delay_lock);
773 return (error == 0 ? EINTR : 0);
774 }
775
776 /*
777 * XXX It would be nice not to have to alloc each time, but it
778 * requires another per thread structure hook. This can be
779 * implemented later if data suggests that it's necessary.
780 */
781 if ((ps = curthread->t_pollstate) == NULL) {
782 curthread->t_pollstate = pollstate_create();
783 ps = curthread->t_pollstate;
784 }
785 if (ps->ps_dpbufsize < nfds) {
786 struct proc *p = ttoproc(curthread);
787 /*
788 * The maximum size should be no large than
789 * current maximum open file count.
790 */
791 mutex_enter(&p->p_lock);
792 if (nfds > p->p_fno_ctl) {
793 mutex_exit(&p->p_lock);
794 DP_REFRELE(dpep);
795 return (EINVAL);
796 }
797 mutex_exit(&p->p_lock);
798 kmem_free(ps->ps_dpbuf, sizeof (pollfd_t) *
799 ps->ps_dpbufsize);
800 ps->ps_dpbuf = kmem_zalloc(sizeof (pollfd_t) *
801 nfds, KM_SLEEP);
802 ps->ps_dpbufsize = nfds;
803 }
804
805 mutex_enter(&pcp->pc_lock);
806 for (;;) {
807 pcp->pc_flag = 0;
808 error = dp_pcache_poll(ps->ps_dpbuf, pcp, nfds, &fdcnt);
809 if (fdcnt > 0 || error != 0)
810 break;
811
812 /*
813 * A pollwake has happened since we polled cache.
814 */
815 if (pcp->pc_flag & T_POLLWAKE)
816 continue;
817
818 /*
819 * Sleep until we are notified, signaled, or timed out.
820 */
821 if (deadline == 0) {
822 /* immediate timeout; do not check signals */
823 break;
824 }
825 error = cv_timedwait_sig_hrtime(&pcp->pc_cv,
826 &pcp->pc_lock, deadline);
827 /*
828 * If we were awakened by a signal or timeout
829 * then break the loop, else poll again.
830 */
831 if (error <= 0) {
832 error = (error == 0) ? EINTR : 0;
833 break;
834 } else {
835 error = 0;
836 }
837 }
838 mutex_exit(&pcp->pc_lock);
839
840 if (error == 0 && fdcnt > 0) {
841 if (copyout(ps->ps_dpbuf, STRUCT_FGETP(dvpoll,
842 dp_fds), sizeof (pollfd_t) * fdcnt)) {
843 DP_REFRELE(dpep);
844 return (EFAULT);
845 }
846 *rvalp = fdcnt;
847 }
848 break;
849 }
850
851 case DP_ISPOLLED:
852 {
853 pollfd_t pollfd;
854 polldat_t *pdp;
855
856 STRUCT_INIT(dvpoll, mode);
857 error = copyin((caddr_t)arg, &pollfd, sizeof (pollfd_t));
858 if (error) {
859 DP_REFRELE(dpep);
860 return (EFAULT);
861 }
862 mutex_enter(&pcp->pc_lock);
863 if (pcp->pc_hash == NULL) {
864 /*
865 * No Need to search because no poll fd
866 * has been cached.
867 */
868 mutex_exit(&pcp->pc_lock);
869 DP_REFRELE(dpep);
870 return (0);
871 }
872 if (pollfd.fd < 0) {
873 mutex_exit(&pcp->pc_lock);
874 break;
875 }
876 pdp = pcache_lookup_fd(pcp, pollfd.fd);
877 if ((pdp != NULL) && (pdp->pd_fd == pollfd.fd) &&
878 (pdp->pd_fp != NULL)) {
879 pollfd.revents = pdp->pd_events;
880 if (copyout(&pollfd, (caddr_t)arg, sizeof (pollfd_t))) {
881 mutex_exit(&pcp->pc_lock);
882 DP_REFRELE(dpep);
883 return (EFAULT);
884 }
885 *rvalp = 1;
886 }
887 mutex_exit(&pcp->pc_lock);
888 break;
889 }
890
891 default:
892 DP_REFRELE(dpep);
893 return (EINVAL);
894 }
895 DP_REFRELE(dpep);
896 return (error);
897 }
898
899 /*ARGSUSED*/
900 static int
901 dppoll(dev_t dev, short events, int anyyet, short *reventsp,
902 struct pollhead **phpp)
903 {
904 /*
905 * Polling on a /dev/poll fd is not fully supported yet.
906 */
907 *reventsp = POLLERR;
908 return (0);
909 }
910
911 /*
912 * devpoll close should do enough clean up before the pollcache is deleted,
913 * i.e., it should ensure no one still references the pollcache later.
914 * There is no "permission" check in here. Any process having the last
915 * reference of this /dev/poll fd can close.
916 */
917 /*ARGSUSED*/
918 static int
919 dpclose(dev_t dev, int flag, int otyp, cred_t *credp)
920 {
921 minor_t minor;
922 dp_entry_t *dpep;
923 pollcache_t *pcp;
924 int i;
925 polldat_t **hashtbl;
926 polldat_t *pdp;
927
928 minor = getminor(dev);
929
930 mutex_enter(&devpoll_lock);
931 dpep = devpolltbl[minor];
932 ASSERT(dpep != NULL);
933 devpolltbl[minor] = NULL;
934 mutex_exit(&devpoll_lock);
935 pcp = dpep->dpe_pcache;
936 ASSERT(pcp != NULL);
937 /*
938 * At this point, no other lwp can access this pollcache via the
939 * /dev/poll fd. This pollcache is going away, so do the clean
940 * up without the pc_lock.
941 */
942 hashtbl = pcp->pc_hash;
943 for (i = 0; i < pcp->pc_hashsize; i++) {
944 for (pdp = hashtbl[i]; pdp; pdp = pdp->pd_hashnext) {
945 if (pdp->pd_php != NULL) {
946 pollhead_delete(pdp->pd_php, pdp);
947 pdp->pd_php = NULL;
948 pdp->pd_fp = NULL;
949 }
950 }
951 }
952 /*
953 * pollwakeup() may still interact with this pollcache. Wait until
954 * it is done.
955 */
956 mutex_enter(&pcp->pc_no_exit);
957 ASSERT(pcp->pc_busy >= 0);
958 while (pcp->pc_busy > 0)
959 cv_wait(&pcp->pc_busy_cv, &pcp->pc_no_exit);
960 mutex_exit(&pcp->pc_no_exit);
961 pcache_destroy(pcp);
962 ASSERT(dpep->dpe_refcnt == 0);
963 kmem_free(dpep, sizeof (dp_entry_t));
964 return (0);
965 }