FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
1 /*-
2 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org>
3 * Copyright (c) 2003-2005 SPARTA, Inc.
4 * Copyright (c) 2005 Robert N. M. Watson
5 * All rights reserved.
6 *
7 * This software was developed for the FreeBSD Project in part by Network
8 * Associates Laboratories, the Security Research Division of Network
9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
10 * as part of the DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_mac.h"
38 #include "opt_posix.h"
39
40 #include <sys/param.h>
41 #include <sys/condvar.h>
42 #include <sys/fcntl.h>
43 #include <sys/file.h>
44 #include <sys/filedesc.h>
45 #include <sys/fnv_hash.h>
46 #include <sys/kernel.h>
47 #include <sys/ksem.h>
48 #include <sys/lock.h>
49 #include <sys/malloc.h>
50 #include <sys/module.h>
51 #include <sys/mutex.h>
52 #include <sys/priv.h>
53 #include <sys/proc.h>
54 #include <sys/posix4.h>
55 #include <sys/refcount.h>
56 #include <sys/semaphore.h>
57 #include <sys/_semaphore.h>
58 #include <sys/stat.h>
59 #include <sys/syscall.h>
60 #include <sys/syscallsubr.h>
61 #include <sys/sysctl.h>
62 #include <sys/sysent.h>
63 #include <sys/sysproto.h>
64 #include <sys/systm.h>
65 #include <sys/sx.h>
66 #include <sys/vnode.h>
67
68 #include <security/mac/mac_framework.h>
69
70 /*
71 * TODO
72 *
73 * - Resource limits?
74 * - Update fstat(1)
75 * - Replace global sem_lock with mtx_pool locks?
76 * - Add a MAC check_create() hook for creating new named semaphores.
77 */
78
79 #ifndef SEM_MAX
80 #define SEM_MAX 30
81 #endif
82
83 #ifdef SEM_DEBUG
84 #define DP(x) printf x
85 #else
86 #define DP(x)
87 #endif
88
89 struct ksem_mapping {
90 char *km_path;
91 Fnv32_t km_fnv;
92 struct ksem *km_ksem;
93 LIST_ENTRY(ksem_mapping) km_link;
94 };
95
96 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
97 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
98 static struct sx ksem_dict_lock;
99 static struct mtx ksem_count_lock;
100 static struct mtx sem_lock;
101 static u_long ksem_hash;
102 static int ksem_dead;
103
104 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash])
105
106 static int nsems = 0;
107 SYSCTL_DECL(_p1003_1b);
108 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
109 "Number of active kernel POSIX semaphores");
110
111 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag,
112 struct timespec *abstime);
113 static int ksem_access(struct ksem *ks, struct ucred *ucred);
114 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
115 unsigned int value);
116 static int ksem_create(struct thread *td, const char *path,
117 semid_t *semidp, mode_t mode, unsigned int value,
118 int flags);
119 static void ksem_drop(struct ksem *ks);
120 static int ksem_get(struct thread *td, semid_t id, struct file **fpp);
121 static struct ksem *ksem_hold(struct ksem *ks);
122 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
123 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
124 static void ksem_module_destroy(void);
125 static int ksem_module_init(void);
126 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
127 static int sem_modload(struct module *module, int cmd, void *arg);
128
129 static fo_rdwr_t ksem_read;
130 static fo_rdwr_t ksem_write;
131 static fo_ioctl_t ksem_ioctl;
132 static fo_poll_t ksem_poll;
133 static fo_kqfilter_t ksem_kqfilter;
134 static fo_stat_t ksem_stat;
135 static fo_close_t ksem_closef;
136
137 /* File descriptor operations. */
138 static struct fileops ksem_ops = {
139 .fo_read = ksem_read,
140 .fo_write = ksem_write,
141 .fo_ioctl = ksem_ioctl,
142 .fo_poll = ksem_poll,
143 .fo_kqfilter = ksem_kqfilter,
144 .fo_stat = ksem_stat,
145 .fo_close = ksem_closef,
146 .fo_flags = DFLAG_PASSABLE
147 };
148
149 FEATURE(posix_sem, "POSIX semaphores");
150
151 static int
152 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
153 int flags, struct thread *td)
154 {
155
156 return (EOPNOTSUPP);
157 }
158
159 static int
160 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
161 int flags, struct thread *td)
162 {
163
164 return (EOPNOTSUPP);
165 }
166
167 static int
168 ksem_ioctl(struct file *fp, u_long com, void *data,
169 struct ucred *active_cred, struct thread *td)
170 {
171
172 return (EOPNOTSUPP);
173 }
174
175 static int
176 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
177 struct thread *td)
178 {
179
180 return (EOPNOTSUPP);
181 }
182
183 static int
184 ksem_kqfilter(struct file *fp, struct knote *kn)
185 {
186
187 return (EOPNOTSUPP);
188 }
189
190 static int
191 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
192 struct thread *td)
193 {
194 struct ksem *ks;
195 #ifdef MAC
196 int error;
197 #endif
198
199 ks = fp->f_data;
200
201 #ifdef MAC
202 /*
203 * XXX: This isn't quite right, but adding a new stat() hook
204 * would break the ABI. This seems to be the closest match of
205 * the existing MAC hooks for POSIX semaphores in 7.
206 */
207 error = mac_check_posix_sem_getvalue(active_cred, ks);
208 if (error)
209 return (error);
210 #endif
211
212 /*
213 * Attempt to return sanish values for fstat() on a semaphore
214 * file descriptor.
215 */
216 bzero(sb, sizeof(*sb));
217 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
218
219 sb->st_atimespec = ks->ks_atime;
220 sb->st_ctimespec = ks->ks_ctime;
221 sb->st_mtimespec = ks->ks_mtime;
222 sb->st_birthtimespec = ks->ks_birthtime;
223 sb->st_uid = ks->ks_uid;
224 sb->st_gid = ks->ks_gid;
225
226 return (0);
227 }
228
229 static int
230 ksem_closef(struct file *fp, struct thread *td)
231 {
232 struct ksem *ks;
233
234 ks = fp->f_data;
235 fp->f_data = NULL;
236 ksem_drop(ks);
237
238 return (0);
239 }
240
241 /*
242 * ksem object management including creation and reference counting
243 * routines.
244 */
245 static struct ksem *
246 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
247 {
248 struct ksem *ks;
249
250 mtx_lock(&ksem_count_lock);
251 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
252 mtx_unlock(&ksem_count_lock);
253 return (NULL);
254 }
255 nsems++;
256 mtx_unlock(&ksem_count_lock);
257 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
258 ks->ks_uid = ucred->cr_uid;
259 ks->ks_gid = ucred->cr_gid;
260 ks->ks_mode = mode;
261 ks->ks_value = value;
262 cv_init(&ks->ks_cv, "ksem");
263 vfs_timestamp(&ks->ks_birthtime);
264 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
265 refcount_init(&ks->ks_ref, 1);
266 #ifdef MAC
267 mac_init_posix_sem(ks);
268 mac_create_posix_sem(ucred, ks);
269 #endif
270
271 return (ks);
272 }
273
274 static struct ksem *
275 ksem_hold(struct ksem *ks)
276 {
277
278 refcount_acquire(&ks->ks_ref);
279 return (ks);
280 }
281
282 static void
283 ksem_drop(struct ksem *ks)
284 {
285
286 if (refcount_release(&ks->ks_ref)) {
287 #ifdef MAC
288 mac_destroy_posix_sem(ks);
289 #endif
290 cv_destroy(&ks->ks_cv);
291 free(ks, M_KSEM);
292 mtx_lock(&ksem_count_lock);
293 nsems--;
294 mtx_unlock(&ksem_count_lock);
295 }
296 }
297
298 /*
299 * Determine if the credentials have sufficient permissions for read
300 * and write access.
301 */
302 static int
303 ksem_access(struct ksem *ks, struct ucred *ucred)
304 {
305 int error;
306
307 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
308 VREAD | VWRITE, ucred, NULL);
309 if (error)
310 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
311 return (error);
312 }
313
314 /*
315 * Dictionary management. We maintain an in-kernel dictionary to map
316 * paths to semaphore objects. We use the FNV hash on the path to
317 * store the mappings in a hash table.
318 */
319 static struct ksem *
320 ksem_lookup(char *path, Fnv32_t fnv)
321 {
322 struct ksem_mapping *map;
323
324 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
325 if (map->km_fnv != fnv)
326 continue;
327 if (strcmp(map->km_path, path) == 0)
328 return (map->km_ksem);
329 }
330
331 return (NULL);
332 }
333
334 static void
335 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
336 {
337 struct ksem_mapping *map;
338
339 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
340 map->km_path = path;
341 map->km_fnv = fnv;
342 map->km_ksem = ksem_hold(ks);
343 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
344 }
345
346 static int
347 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
348 {
349 struct ksem_mapping *map;
350 int error;
351
352 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
353 if (map->km_fnv != fnv)
354 continue;
355 if (strcmp(map->km_path, path) == 0) {
356 #ifdef MAC
357 error = mac_check_posix_sem_unlink(ucred, map->km_ksem);
358 if (error)
359 return (error);
360 #endif
361 error = ksem_access(map->km_ksem, ucred);
362 if (error)
363 return (error);
364 LIST_REMOVE(map, km_link);
365 ksem_drop(map->km_ksem);
366 free(map->km_path, M_KSEM);
367 free(map, M_KSEM);
368 return (0);
369 }
370 }
371
372 return (ENOENT);
373 }
374
375 /* Other helper routines. */
376 static int
377 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
378 unsigned int value, int flags)
379 {
380 struct filedesc *fdp;
381 struct ksem *ks;
382 struct file *fp;
383 char *path;
384 semid_t semid;
385 Fnv32_t fnv;
386 int error, fd;
387
388 if (value > SEM_VALUE_MAX)
389 return (EINVAL);
390
391 fdp = td->td_proc->p_fd;
392 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
393 error = falloc(td, &fp, &fd);
394 if (error) {
395 if (name == NULL)
396 error = ENOSPC;
397 return (error);
398 }
399
400 /*
401 * Go ahead and copyout the file descriptor now. This is a bit
402 * premature, but it is a lot easier to handle errors as opposed
403 * to later when we've possibly created a new semaphore, etc.
404 */
405 semid = fd;
406 error = copyout(&semid, semidp, sizeof(semid));
407 if (error) {
408 fdclose(fdp, fp, fd, td);
409 fdrop(fp, td);
410 return (error);
411 }
412
413 if (name == NULL) {
414 /* Create an anonymous semaphore. */
415 ks = ksem_alloc(td->td_ucred, mode, value);
416 if (ks == NULL)
417 error = ENOSPC;
418 else
419 ks->ks_flags |= KS_ANONYMOUS;
420 } else {
421 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
422 error = copyinstr(name, path, MAXPATHLEN, NULL);
423
424 /* Require paths to start with a '/' character. */
425 if (error == 0 && path[0] != '/')
426 error = EINVAL;
427 if (error) {
428 fdclose(fdp, fp, fd, td);
429 fdrop(fp, td);
430 free(path, M_KSEM);
431 return (error);
432 }
433
434 fnv = fnv_32_str(path, FNV1_32_INIT);
435 sx_xlock(&ksem_dict_lock);
436 ks = ksem_lookup(path, fnv);
437 if (ks == NULL) {
438 /* Object does not exist, create it if requested. */
439 if (flags & O_CREAT) {
440 ks = ksem_alloc(td->td_ucred, mode, value);
441 if (ks == NULL)
442 error = ENFILE;
443 else {
444 ksem_insert(path, fnv, ks);
445 path = NULL;
446 }
447 } else
448 error = ENOENT;
449 } else {
450 /*
451 * Object already exists, obtain a new
452 * reference if requested and permitted.
453 */
454 if ((flags & (O_CREAT | O_EXCL)) ==
455 (O_CREAT | O_EXCL))
456 error = EEXIST;
457 else {
458 #ifdef MAC
459 error = mac_check_posix_sem_open(td->td_ucred,
460 ks);
461 if (error == 0)
462 #endif
463 error = ksem_access(ks, td->td_ucred);
464 }
465 if (error == 0)
466 ksem_hold(ks);
467 #ifdef INVARIANTS
468 else
469 ks = NULL;
470 #endif
471 }
472 sx_xunlock(&ksem_dict_lock);
473 if (path)
474 free(path, M_KSEM);
475 }
476
477 if (error) {
478 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
479 fdclose(fdp, fp, fd, td);
480 fdrop(fp, td);
481 return (error);
482 }
483 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
484
485 fp->f_data = ks;
486 fp->f_flag = FREAD | FWRITE;
487 fp->f_type = DTYPE_SEM;
488 fp->f_ops = &ksem_ops;
489
490 FILEDESC_XLOCK(fdp);
491 if (fdp->fd_ofiles[fd] == fp)
492 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
493 FILEDESC_XUNLOCK(fdp);
494 fdrop(fp, td);
495
496 return (0);
497 }
498
499 static int
500 ksem_get(struct thread *td, semid_t id, struct file **fpp)
501 {
502 struct ksem *ks;
503 struct file *fp;
504 int error;
505
506 error = fget(td, id, &fp);
507 if (error)
508 return (EINVAL);
509 if (fp->f_type != DTYPE_SEM) {
510 fdrop(fp, td);
511 return (EINVAL);
512 }
513 ks = fp->f_data;
514 if (ks->ks_flags & KS_DEAD) {
515 fdrop(fp, td);
516 return (EINVAL);
517 }
518 *fpp = fp;
519 return (0);
520 }
521
522 /* System calls. */
523 #ifndef _SYS_SYSPROTO_H_
524 struct ksem_init_args {
525 unsigned int value;
526 semid_t *idp;
527 };
528 #endif
529 int
530 ksem_init(struct thread *td, struct ksem_init_args *uap)
531 {
532
533 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
534 0));
535 }
536
537 #ifndef _SYS_SYSPROTO_H_
538 struct ksem_open_args {
539 char *name;
540 int oflag;
541 mode_t mode;
542 unsigned int value;
543 semid_t *idp;
544 };
545 #endif
546 int
547 ksem_open(struct thread *td, struct ksem_open_args *uap)
548 {
549
550 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
551 return (EINVAL);
552 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
553 uap->oflag));
554 }
555
556 #ifndef _SYS_SYSPROTO_H_
557 struct ksem_unlink_args {
558 char *name;
559 };
560 #endif
561 int
562 ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
563 {
564 char *path;
565 Fnv32_t fnv;
566 int error;
567
568 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
569 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
570 if (error) {
571 free(path, M_TEMP);
572 return (error);
573 }
574
575 fnv = fnv_32_str(path, FNV1_32_INIT);
576 sx_xlock(&ksem_dict_lock);
577 error = ksem_remove(path, fnv, td->td_ucred);
578 sx_xunlock(&ksem_dict_lock);
579 free(path, M_TEMP);
580
581 return (error);
582 }
583
584 #ifndef _SYS_SYSPROTO_H_
585 struct ksem_close_args {
586 semid_t id;
587 };
588 #endif
589 int
590 ksem_close(struct thread *td, struct ksem_close_args *uap)
591 {
592 struct ksem *ks;
593 struct file *fp;
594 int error;
595
596 error = ksem_get(td, uap->id, &fp);
597 if (error)
598 return (error);
599 ks = fp->f_data;
600 if (ks->ks_flags & KS_ANONYMOUS) {
601 fdrop(fp, td);
602 return (EINVAL);
603 }
604 error = kern_close(td, uap->id);
605 fdrop(fp, td);
606 return (error);
607 }
608
609 #ifndef _SYS_SYSPROTO_H_
610 struct ksem_post_args {
611 semid_t id;
612 };
613 #endif
614 int
615 ksem_post(struct thread *td, struct ksem_post_args *uap)
616 {
617 struct file *fp;
618 struct ksem *ks;
619 int error;
620
621 error = ksem_get(td, uap->id, &fp);
622 if (error)
623 return (error);
624 ks = fp->f_data;
625
626 mtx_lock(&sem_lock);
627 #ifdef MAC
628 error = mac_check_posix_sem_post(td->td_ucred, ks);
629 if (error)
630 goto err;
631 #endif
632 if (ks->ks_value == SEM_VALUE_MAX) {
633 error = EOVERFLOW;
634 goto err;
635 }
636 ++ks->ks_value;
637 if (ks->ks_waiters > 0)
638 cv_signal(&ks->ks_cv);
639 error = 0;
640 vfs_timestamp(&ks->ks_ctime);
641 err:
642 mtx_unlock(&sem_lock);
643 fdrop(fp, td);
644 return (error);
645 }
646
647 #ifndef _SYS_SYSPROTO_H_
648 struct ksem_wait_args {
649 semid_t id;
650 };
651 #endif
652 int
653 ksem_wait(struct thread *td, struct ksem_wait_args *uap)
654 {
655
656 return (kern_sem_wait(td, uap->id, 0, NULL));
657 }
658
659 #ifndef _SYS_SYSPROTO_H_
660 struct ksem_timedwait_args {
661 semid_t id;
662 const struct timespec *abstime;
663 };
664 #endif
665 int
666 ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
667 {
668 struct timespec abstime;
669 struct timespec *ts;
670 int error;
671
672 /*
673 * We allow a null timespec (wait forever).
674 */
675 if (uap->abstime == NULL)
676 ts = NULL;
677 else {
678 error = copyin(uap->abstime, &abstime, sizeof(abstime));
679 if (error != 0)
680 return (error);
681 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
682 return (EINVAL);
683 ts = &abstime;
684 }
685 return (kern_sem_wait(td, uap->id, 0, ts));
686 }
687
688 #ifndef _SYS_SYSPROTO_H_
689 struct ksem_trywait_args {
690 semid_t id;
691 };
692 #endif
693 int
694 ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
695 {
696
697 return (kern_sem_wait(td, uap->id, 1, NULL));
698 }
699
700 static int
701 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
702 struct timespec *abstime)
703 {
704 struct timespec ts1, ts2;
705 struct timeval tv;
706 struct file *fp;
707 struct ksem *ks;
708 int error;
709
710 DP((">>> kern_sem_wait entered!\n"));
711 error = ksem_get(td, id, &fp);
712 if (error)
713 return (error);
714 ks = fp->f_data;
715 mtx_lock(&sem_lock);
716 #ifdef MAC
717 error = mac_check_posix_sem_wait(td->td_ucred, ks);
718 if (error) {
719 DP(("kern_sem_wait mac failed\n"));
720 goto err;
721 }
722 #endif
723 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
724 vfs_timestamp(&ks->ks_atime);
725 while (ks->ks_value == 0) {
726 ks->ks_waiters++;
727 if (tryflag != 0)
728 error = EAGAIN;
729 else if (abstime == NULL)
730 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
731 else {
732 for (;;) {
733 ts1 = *abstime;
734 getnanotime(&ts2);
735 timespecsub(&ts1, &ts2);
736 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
737 if (tv.tv_sec < 0) {
738 error = ETIMEDOUT;
739 break;
740 }
741 error = cv_timedwait_sig(&ks->ks_cv,
742 &sem_lock, tvtohz(&tv));
743 if (error != EWOULDBLOCK)
744 break;
745 }
746 }
747 ks->ks_waiters--;
748 if (error)
749 goto err;
750 }
751 ks->ks_value--;
752 error = 0;
753 err:
754 mtx_unlock(&sem_lock);
755 fdrop(fp, td);
756 DP(("<<< kern_sem_wait leaving, error = %d\n", error));
757 return (error);
758 }
759
760 #ifndef _SYS_SYSPROTO_H_
761 struct ksem_getvalue_args {
762 semid_t id;
763 int *val;
764 };
765 #endif
766 int
767 ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
768 {
769 struct file *fp;
770 struct ksem *ks;
771 int error, val;
772
773 error = ksem_get(td, uap->id, &fp);
774 if (error)
775 return (error);
776 ks = fp->f_data;
777
778 mtx_lock(&sem_lock);
779 #ifdef MAC
780 error = mac_check_posix_sem_getvalue(td->td_ucred, ks);
781 if (error) {
782 mtx_unlock(&sem_lock);
783 fdrop(fp, td);
784 return (error);
785 }
786 #endif
787 val = ks->ks_value;
788 vfs_timestamp(&ks->ks_atime);
789 mtx_unlock(&sem_lock);
790 fdrop(fp, td);
791 error = copyout(&val, uap->val, sizeof(val));
792 return (error);
793 }
794
795 #ifndef _SYS_SYSPROTO_H_
796 struct ksem_destroy_args {
797 semid_t id;
798 };
799 #endif
800 int
801 ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
802 {
803 struct file *fp;
804 struct ksem *ks;
805 int error;
806
807 error = ksem_get(td, uap->id, &fp);
808 if (error)
809 return (error);
810 ks = fp->f_data;
811 if (!(ks->ks_flags & KS_ANONYMOUS)) {
812 fdrop(fp, td);
813 return (EINVAL);
814 }
815 mtx_lock(&sem_lock);
816 if (ks->ks_waiters != 0) {
817 mtx_unlock(&sem_lock);
818 error = EBUSY;
819 goto err;
820 }
821 ks->ks_flags |= KS_DEAD;
822 mtx_unlock(&sem_lock);
823
824 error = kern_close(td, uap->id);
825 err:
826 fdrop(fp, td);
827 return (error);
828 }
829
830 #define SYSCALL_DATA(syscallname) \
831 static int syscallname##_syscall = SYS_##syscallname; \
832 static int syscallname##_registered; \
833 static struct sysent syscallname##_old_sysent; \
834 MAKE_SYSENT(syscallname);
835
836 #define SYSCALL_REGISTER(syscallname) do { \
837 error = syscall_register(& syscallname##_syscall, \
838 & syscallname##_sysent, & syscallname##_old_sysent); \
839 if (error) \
840 return (error); \
841 syscallname##_registered = 1; \
842 } while(0)
843
844 #define SYSCALL_DEREGISTER(syscallname) do { \
845 if (syscallname##_registered) { \
846 syscallname##_registered = 0; \
847 syscall_deregister(& syscallname##_syscall, \
848 & syscallname##_old_sysent); \
849 } \
850 } while(0)
851
852 SYSCALL_DATA(ksem_init);
853 SYSCALL_DATA(ksem_open);
854 SYSCALL_DATA(ksem_unlink);
855 SYSCALL_DATA(ksem_close);
856 SYSCALL_DATA(ksem_post);
857 SYSCALL_DATA(ksem_wait);
858 SYSCALL_DATA(ksem_timedwait);
859 SYSCALL_DATA(ksem_trywait);
860 SYSCALL_DATA(ksem_getvalue);
861 SYSCALL_DATA(ksem_destroy);
862
863 static int
864 ksem_module_init(void)
865 {
866 int error;
867
868 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
869 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
870 sx_init(&ksem_dict_lock, "ksem dictionary");
871 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
872 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
873 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
874 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
875
876 SYSCALL_REGISTER(ksem_init);
877 SYSCALL_REGISTER(ksem_open);
878 SYSCALL_REGISTER(ksem_unlink);
879 SYSCALL_REGISTER(ksem_close);
880 SYSCALL_REGISTER(ksem_post);
881 SYSCALL_REGISTER(ksem_wait);
882 SYSCALL_REGISTER(ksem_timedwait);
883 SYSCALL_REGISTER(ksem_trywait);
884 SYSCALL_REGISTER(ksem_getvalue);
885 SYSCALL_REGISTER(ksem_destroy);
886 return (0);
887 }
888
889 static void
890 ksem_module_destroy(void)
891 {
892
893 SYSCALL_DEREGISTER(ksem_init);
894 SYSCALL_DEREGISTER(ksem_open);
895 SYSCALL_DEREGISTER(ksem_unlink);
896 SYSCALL_DEREGISTER(ksem_close);
897 SYSCALL_DEREGISTER(ksem_post);
898 SYSCALL_DEREGISTER(ksem_wait);
899 SYSCALL_DEREGISTER(ksem_timedwait);
900 SYSCALL_DEREGISTER(ksem_trywait);
901 SYSCALL_DEREGISTER(ksem_getvalue);
902 SYSCALL_DEREGISTER(ksem_destroy);
903
904 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
905 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
906 sx_destroy(&ksem_dict_lock);
907 mtx_destroy(&ksem_count_lock);
908 mtx_destroy(&sem_lock);
909 }
910
911 static int
912 sem_modload(struct module *module, int cmd, void *arg)
913 {
914 int error = 0;
915
916 switch (cmd) {
917 case MOD_LOAD:
918 error = ksem_module_init();
919 if (error)
920 ksem_module_destroy();
921 break;
922
923 case MOD_UNLOAD:
924 mtx_lock(&ksem_count_lock);
925 if (nsems != 0) {
926 error = EOPNOTSUPP;
927 mtx_unlock(&ksem_count_lock);
928 break;
929 }
930 ksem_dead = 1;
931 mtx_unlock(&ksem_count_lock);
932 ksem_module_destroy();
933 break;
934
935 case MOD_SHUTDOWN:
936 break;
937 default:
938 error = EINVAL;
939 break;
940 }
941 return (error);
942 }
943
944 static moduledata_t sem_mod = {
945 "sem",
946 &sem_modload,
947 NULL
948 };
949
950 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
951 MODULE_VERSION(sem, 1);
Cache object: b909fc51fa9436a2bbf1989a50754e25
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