FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_sem.c
1 /* $NetBSD: sysv_sem.c,v 1.84 2008/09/19 11:21:33 rmind Exp $ */
2
3 /*-
4 * Copyright (c) 1999, 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center, and by Andrew Doran.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*
34 * Implementation of SVID semaphores
35 *
36 * Author: Daniel Boulet
37 *
38 * This software is provided ``AS IS'' without any warranties of any kind.
39 */
40
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.84 2008/09/19 11:21:33 rmind Exp $");
43
44 #define SYSVSEM
45
46 #include <sys/param.h>
47 #include <sys/kernel.h>
48 #include <sys/sem.h>
49 #include <sys/sysctl.h>
50 #include <sys/kmem.h>
51 #include <sys/mount.h> /* XXX for <sys/syscallargs.h> */
52 #include <sys/syscallargs.h>
53 #include <sys/kauth.h>
54
55 /*
56 * Memory areas:
57 * 1st: Pool of semaphore identifiers
58 * 2nd: Semaphores
59 * 3rd: Conditional variables
60 * 4th: Undo structures
61 */
62 struct semid_ds *sema;
63 static struct __sem *sem;
64 static kcondvar_t *semcv;
65 static int *semu;
66
67 static kmutex_t semlock;
68 static struct sem_undo *semu_list; /* list of active undo structures */
69 static u_int semtot = 0; /* total number of semaphores */
70
71 static u_int sem_waiters = 0; /* total number of semop waiters */
72 static bool sem_realloc_state;
73 static kcondvar_t sem_realloc_cv;
74
75 /* Macro to find a particular sem_undo vector */
76 #define SEMU(s, ix) ((struct sem_undo *)(((long)s) + ix * seminfo.semusz))
77
78 #ifdef SEM_DEBUG
79 #define SEM_PRINTF(a) printf a
80 #else
81 #define SEM_PRINTF(a)
82 #endif
83
84 struct sem_undo *semu_alloc(struct proc *);
85 int semundo_adjust(struct proc *, struct sem_undo **, int, int, int);
86 void semundo_clear(int, int);
87
88 void
89 seminit(void)
90 {
91 int i, sz;
92 vaddr_t v;
93
94 mutex_init(&semlock, MUTEX_DEFAULT, IPL_NONE);
95 cv_init(&sem_realloc_cv, "semrealc");
96 sem_realloc_state = false;
97
98 /* Allocate the wired memory for our structures */
99 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
100 ALIGN(seminfo.semmns * sizeof(struct __sem)) +
101 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
102 ALIGN(seminfo.semmnu * seminfo.semusz);
103 v = uvm_km_alloc(kernel_map, round_page(sz), 0,
104 UVM_KMF_WIRED|UVM_KMF_ZERO);
105 if (v == 0)
106 panic("sysv_sem: cannot allocate memory");
107 sema = (void *)v;
108 sem = (void *)((uintptr_t)sema +
109 ALIGN(seminfo.semmni * sizeof(struct semid_ds)));
110 semcv = (void *)((uintptr_t)sem +
111 ALIGN(seminfo.semmns * sizeof(struct __sem)));
112 semu = (void *)((uintptr_t)semcv +
113 ALIGN(seminfo.semmni * sizeof(kcondvar_t)));
114
115 for (i = 0; i < seminfo.semmni; i++) {
116 sema[i]._sem_base = 0;
117 sema[i].sem_perm.mode = 0;
118 cv_init(&semcv[i], "semwait");
119 }
120 for (i = 0; i < seminfo.semmnu; i++) {
121 struct sem_undo *suptr = SEMU(semu, i);
122 suptr->un_proc = NULL;
123 }
124 semu_list = NULL;
125 exithook_establish(semexit, NULL);
126 }
127
128 static int
129 semrealloc(int newsemmni, int newsemmns, int newsemmnu)
130 {
131 struct semid_ds *new_sema, *old_sema;
132 struct __sem *new_sem;
133 struct sem_undo *new_semu_list, *suptr, *nsuptr;
134 int *new_semu;
135 kcondvar_t *new_semcv;
136 vaddr_t v;
137 int i, j, lsemid, nmnus, sz;
138
139 if (newsemmni < 1 || newsemmns < 1 || newsemmnu < 1)
140 return EINVAL;
141
142 /* Allocate the wired memory for our structures */
143 sz = ALIGN(newsemmni * sizeof(struct semid_ds)) +
144 ALIGN(newsemmns * sizeof(struct __sem)) +
145 ALIGN(newsemmni * sizeof(kcondvar_t)) +
146 ALIGN(newsemmnu * seminfo.semusz);
147 v = uvm_km_alloc(kernel_map, round_page(sz), 0,
148 UVM_KMF_WIRED|UVM_KMF_ZERO);
149 if (v == 0)
150 return ENOMEM;
151
152 mutex_enter(&semlock);
153 if (sem_realloc_state) {
154 mutex_exit(&semlock);
155 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
156 return EBUSY;
157 }
158 sem_realloc_state = true;
159 if (sem_waiters) {
160 /*
161 * Mark reallocation state, wake-up all waiters,
162 * and wait while they will all exit.
163 */
164 for (i = 0; i < seminfo.semmni; i++)
165 cv_broadcast(&semcv[i]);
166 while (sem_waiters)
167 cv_wait(&sem_realloc_cv, &semlock);
168 }
169 old_sema = sema;
170
171 /* Get the number of last slot */
172 lsemid = 0;
173 for (i = 0; i < seminfo.semmni; i++)
174 if (sema[i].sem_perm.mode & SEM_ALLOC)
175 lsemid = i;
176
177 /* Get the number of currently used undo structures */
178 nmnus = 0;
179 for (i = 0; i < seminfo.semmnu; i++) {
180 suptr = SEMU(semu, i);
181 if (suptr->un_proc == NULL)
182 continue;
183 nmnus++;
184 }
185
186 /* We cannot reallocate less memory than we use */
187 if (lsemid >= newsemmni || semtot > newsemmns || nmnus > newsemmnu) {
188 mutex_exit(&semlock);
189 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
190 return EBUSY;
191 }
192
193 new_sema = (void *)v;
194 new_sem = (void *)((uintptr_t)new_sema +
195 ALIGN(newsemmni * sizeof(struct semid_ds)));
196 new_semcv = (void *)((uintptr_t)new_sem +
197 ALIGN(newsemmns * sizeof(struct __sem)));
198 new_semu = (void *)((uintptr_t)new_semcv +
199 ALIGN(newsemmni * sizeof(kcondvar_t)));
200
201 /* Initialize all semaphore identifiers and condvars */
202 for (i = 0; i < newsemmni; i++) {
203 new_sema[i]._sem_base = 0;
204 new_sema[i].sem_perm.mode = 0;
205 cv_init(&new_semcv[i], "semwait");
206 }
207 for (i = 0; i < newsemmnu; i++) {
208 nsuptr = SEMU(new_semu, i);
209 nsuptr->un_proc = NULL;
210 }
211
212 /*
213 * Copy all identifiers, semaphores and list of the
214 * undo structures to the new memory allocation.
215 */
216 j = 0;
217 for (i = 0; i <= lsemid; i++) {
218 if ((sema[i].sem_perm.mode & SEM_ALLOC) == 0)
219 continue;
220 memcpy(&new_sema[i], &sema[i], sizeof(struct semid_ds));
221 new_sema[i]._sem_base = &new_sem[j];
222 memcpy(new_sema[i]._sem_base, sema[i]._sem_base,
223 (sizeof(struct __sem) * sema[i].sem_nsems));
224 j += sema[i].sem_nsems;
225 }
226 KASSERT(j == semtot);
227
228 j = 0;
229 new_semu_list = NULL;
230 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
231 KASSERT(j < newsemmnu);
232 nsuptr = SEMU(new_semu, j);
233 memcpy(nsuptr, suptr, SEMUSZ);
234 nsuptr->un_next = new_semu_list;
235 new_semu_list = nsuptr;
236 j++;
237 }
238
239 for (i = 0; i < seminfo.semmni; i++) {
240 KASSERT(cv_has_waiters(&semcv[i]) == false);
241 cv_destroy(&semcv[i]);
242 }
243
244 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
245 ALIGN(seminfo.semmns * sizeof(struct __sem)) +
246 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
247 ALIGN(seminfo.semmnu * seminfo.semusz);
248
249 /* Set the pointers and update the new values */
250 sema = new_sema;
251 sem = new_sem;
252 semcv = new_semcv;
253 semu = new_semu;
254 semu_list = new_semu_list;
255
256 seminfo.semmni = newsemmni;
257 seminfo.semmns = newsemmns;
258 seminfo.semmnu = newsemmnu;
259
260 /* Reallocation completed - notify all waiters, if any */
261 sem_realloc_state = false;
262 cv_broadcast(&sem_realloc_cv);
263 mutex_exit(&semlock);
264
265 uvm_km_free(kernel_map, (vaddr_t)old_sema, sz, UVM_KMF_WIRED);
266 return 0;
267 }
268
269 /*
270 * Placebo.
271 */
272
273 int
274 sys_semconfig(struct lwp *l, const struct sys_semconfig_args *uap, register_t *retval)
275 {
276
277 *retval = 0;
278 return 0;
279 }
280
281 /*
282 * Allocate a new sem_undo structure for a process
283 * (returns ptr to structure or NULL if no more room)
284 */
285
286 struct sem_undo *
287 semu_alloc(struct proc *p)
288 {
289 int i;
290 struct sem_undo *suptr;
291 struct sem_undo **supptr;
292 int attempt;
293
294 KASSERT(mutex_owned(&semlock));
295
296 /*
297 * Try twice to allocate something.
298 * (we'll purge any empty structures after the first pass so
299 * two passes are always enough)
300 */
301
302 for (attempt = 0; attempt < 2; attempt++) {
303 /*
304 * Look for a free structure.
305 * Fill it in and return it if we find one.
306 */
307
308 for (i = 0; i < seminfo.semmnu; i++) {
309 suptr = SEMU(semu, i);
310 if (suptr->un_proc == NULL) {
311 suptr->un_next = semu_list;
312 semu_list = suptr;
313 suptr->un_cnt = 0;
314 suptr->un_proc = p;
315 return (suptr);
316 }
317 }
318
319 /*
320 * We didn't find a free one, if this is the first attempt
321 * then try to free some structures.
322 */
323
324 if (attempt == 0) {
325 /* All the structures are in use - try to free some */
326 int did_something = 0;
327
328 supptr = &semu_list;
329 while ((suptr = *supptr) != NULL) {
330 if (suptr->un_cnt == 0) {
331 suptr->un_proc = NULL;
332 *supptr = suptr->un_next;
333 did_something = 1;
334 } else
335 supptr = &suptr->un_next;
336 }
337
338 /* If we didn't free anything then just give-up */
339 if (!did_something)
340 return (NULL);
341 } else {
342 /*
343 * The second pass failed even though we freed
344 * something after the first pass!
345 * This is IMPOSSIBLE!
346 */
347 panic("semu_alloc - second attempt failed");
348 }
349 }
350 return NULL;
351 }
352
353 /*
354 * Adjust a particular entry for a particular proc
355 */
356
357 int
358 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
359 int adjval)
360 {
361 struct sem_undo *suptr;
362 struct undo *sunptr;
363 int i;
364
365 KASSERT(mutex_owned(&semlock));
366
367 /*
368 * Look for and remember the sem_undo if the caller doesn't
369 * provide it
370 */
371
372 suptr = *supptr;
373 if (suptr == NULL) {
374 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
375 if (suptr->un_proc == p)
376 break;
377
378 if (suptr == NULL) {
379 suptr = semu_alloc(p);
380 if (suptr == NULL)
381 return (ENOSPC);
382 }
383 *supptr = suptr;
384 }
385
386 /*
387 * Look for the requested entry and adjust it (delete if
388 * adjval becomes 0).
389 */
390 sunptr = &suptr->un_ent[0];
391 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
392 if (sunptr->un_id != semid || sunptr->un_num != semnum)
393 continue;
394 sunptr->un_adjval += adjval;
395 if (sunptr->un_adjval == 0) {
396 suptr->un_cnt--;
397 if (i < suptr->un_cnt)
398 suptr->un_ent[i] =
399 suptr->un_ent[suptr->un_cnt];
400 }
401 return (0);
402 }
403
404 /* Didn't find the right entry - create it */
405 if (suptr->un_cnt == SEMUME)
406 return (EINVAL);
407
408 sunptr = &suptr->un_ent[suptr->un_cnt];
409 suptr->un_cnt++;
410 sunptr->un_adjval = adjval;
411 sunptr->un_id = semid;
412 sunptr->un_num = semnum;
413 return (0);
414 }
415
416 void
417 semundo_clear(int semid, int semnum)
418 {
419 struct sem_undo *suptr;
420 struct undo *sunptr, *sunend;
421
422 KASSERT(mutex_owned(&semlock));
423
424 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
425 for (sunptr = &suptr->un_ent[0],
426 sunend = sunptr + suptr->un_cnt; sunptr < sunend;) {
427 if (sunptr->un_id == semid) {
428 if (semnum == -1 || sunptr->un_num == semnum) {
429 suptr->un_cnt--;
430 sunend--;
431 if (sunptr != sunend)
432 *sunptr = *sunend;
433 if (semnum != -1)
434 break;
435 else
436 continue;
437 }
438 }
439 sunptr++;
440 }
441 }
442
443 int
444 sys_____semctl13(struct lwp *l, const struct sys_____semctl13_args *uap, register_t *retval)
445 {
446 /* {
447 syscallarg(int) semid;
448 syscallarg(int) semnum;
449 syscallarg(int) cmd;
450 syscallarg(union __semun *) arg;
451 } */
452 struct semid_ds sembuf;
453 int cmd, error;
454 void *pass_arg;
455 union __semun karg;
456
457 cmd = SCARG(uap, cmd);
458
459 pass_arg = get_semctl_arg(cmd, &sembuf, &karg);
460
461 if (pass_arg) {
462 error = copyin(SCARG(uap, arg), &karg, sizeof(karg));
463 if (error)
464 return error;
465 if (cmd == IPC_SET) {
466 error = copyin(karg.buf, &sembuf, sizeof(sembuf));
467 if (error)
468 return (error);
469 }
470 }
471
472 error = semctl1(l, SCARG(uap, semid), SCARG(uap, semnum), cmd,
473 pass_arg, retval);
474
475 if (error == 0 && cmd == IPC_STAT)
476 error = copyout(&sembuf, karg.buf, sizeof(sembuf));
477
478 return (error);
479 }
480
481 int
482 semctl1(struct lwp *l, int semid, int semnum, int cmd, void *v,
483 register_t *retval)
484 {
485 kauth_cred_t cred = l->l_cred;
486 union __semun *arg = v;
487 struct semid_ds *sembuf = v, *semaptr;
488 int i, error, ix;
489
490 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n",
491 semid, semnum, cmd, v));
492
493 mutex_enter(&semlock);
494
495 ix = IPCID_TO_IX(semid);
496 if (ix < 0 || ix >= seminfo.semmni) {
497 mutex_exit(&semlock);
498 return (EINVAL);
499 }
500
501 semaptr = &sema[ix];
502 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
503 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) {
504 mutex_exit(&semlock);
505 return (EINVAL);
506 }
507
508 switch (cmd) {
509 case IPC_RMID:
510 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0)
511 break;
512 semaptr->sem_perm.cuid = kauth_cred_geteuid(cred);
513 semaptr->sem_perm.uid = kauth_cred_geteuid(cred);
514 semtot -= semaptr->sem_nsems;
515 for (i = semaptr->_sem_base - sem; i < semtot; i++)
516 sem[i] = sem[i + semaptr->sem_nsems];
517 for (i = 0; i < seminfo.semmni; i++) {
518 if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
519 sema[i]._sem_base > semaptr->_sem_base)
520 sema[i]._sem_base -= semaptr->sem_nsems;
521 }
522 semaptr->sem_perm.mode = 0;
523 semundo_clear(ix, -1);
524 cv_broadcast(&semcv[ix]);
525 break;
526
527 case IPC_SET:
528 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
529 break;
530 KASSERT(sembuf != NULL);
531 semaptr->sem_perm.uid = sembuf->sem_perm.uid;
532 semaptr->sem_perm.gid = sembuf->sem_perm.gid;
533 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
534 (sembuf->sem_perm.mode & 0777);
535 semaptr->sem_ctime = time_second;
536 break;
537
538 case IPC_STAT:
539 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
540 break;
541 KASSERT(sembuf != NULL);
542 memcpy(sembuf, semaptr, sizeof(struct semid_ds));
543 sembuf->sem_perm.mode &= 0777;
544 break;
545
546 case GETNCNT:
547 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
548 break;
549 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
550 error = EINVAL;
551 break;
552 }
553 *retval = semaptr->_sem_base[semnum].semncnt;
554 break;
555
556 case GETPID:
557 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
558 break;
559 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
560 error = EINVAL;
561 break;
562 }
563 *retval = semaptr->_sem_base[semnum].sempid;
564 break;
565
566 case GETVAL:
567 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
568 break;
569 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
570 error = EINVAL;
571 break;
572 }
573 *retval = semaptr->_sem_base[semnum].semval;
574 break;
575
576 case GETALL:
577 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
578 break;
579 KASSERT(arg != NULL);
580 for (i = 0; i < semaptr->sem_nsems; i++) {
581 error = copyout(&semaptr->_sem_base[i].semval,
582 &arg->array[i], sizeof(arg->array[i]));
583 if (error != 0)
584 break;
585 }
586 break;
587
588 case GETZCNT:
589 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
590 break;
591 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
592 error = EINVAL;
593 break;
594 }
595 *retval = semaptr->_sem_base[semnum].semzcnt;
596 break;
597
598 case SETVAL:
599 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
600 break;
601 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
602 error = EINVAL;
603 break;
604 }
605 KASSERT(arg != NULL);
606 if ((unsigned int)arg->val > seminfo.semvmx) {
607 error = ERANGE;
608 break;
609 }
610 semaptr->_sem_base[semnum].semval = arg->val;
611 semundo_clear(ix, semnum);
612 cv_broadcast(&semcv[ix]);
613 break;
614
615 case SETALL:
616 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
617 break;
618 KASSERT(arg != NULL);
619 for (i = 0; i < semaptr->sem_nsems; i++) {
620 unsigned short semval;
621 error = copyin(&arg->array[i], &semval,
622 sizeof(arg->array[i]));
623 if (error != 0)
624 break;
625 if ((unsigned int)semval > seminfo.semvmx) {
626 error = ERANGE;
627 break;
628 }
629 semaptr->_sem_base[i].semval = semval;
630 }
631 semundo_clear(ix, -1);
632 cv_broadcast(&semcv[ix]);
633 break;
634
635 default:
636 error = EINVAL;
637 break;
638 }
639
640 mutex_exit(&semlock);
641 return (error);
642 }
643
644 int
645 sys_semget(struct lwp *l, const struct sys_semget_args *uap, register_t *retval)
646 {
647 /* {
648 syscallarg(key_t) key;
649 syscallarg(int) nsems;
650 syscallarg(int) semflg;
651 } */
652 int semid, error = 0;
653 int key = SCARG(uap, key);
654 int nsems = SCARG(uap, nsems);
655 int semflg = SCARG(uap, semflg);
656 kauth_cred_t cred = l->l_cred;
657
658 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
659
660 mutex_enter(&semlock);
661
662 if (key != IPC_PRIVATE) {
663 for (semid = 0; semid < seminfo.semmni; semid++) {
664 if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
665 sema[semid].sem_perm._key == key)
666 break;
667 }
668 if (semid < seminfo.semmni) {
669 SEM_PRINTF(("found public key\n"));
670 if ((error = ipcperm(cred, &sema[semid].sem_perm,
671 semflg & 0700)))
672 goto out;
673 if (nsems > 0 && sema[semid].sem_nsems < nsems) {
674 SEM_PRINTF(("too small\n"));
675 error = EINVAL;
676 goto out;
677 }
678 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
679 SEM_PRINTF(("not exclusive\n"));
680 error = EEXIST;
681 goto out;
682 }
683 goto found;
684 }
685 }
686
687 SEM_PRINTF(("need to allocate the semid_ds\n"));
688 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
689 if (nsems <= 0 || nsems > seminfo.semmsl) {
690 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
691 seminfo.semmsl));
692 error = EINVAL;
693 goto out;
694 }
695 if (nsems > seminfo.semmns - semtot) {
696 SEM_PRINTF(("not enough semaphores left "
697 "(need %d, got %d)\n",
698 nsems, seminfo.semmns - semtot));
699 error = ENOSPC;
700 goto out;
701 }
702 for (semid = 0; semid < seminfo.semmni; semid++) {
703 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
704 break;
705 }
706 if (semid == seminfo.semmni) {
707 SEM_PRINTF(("no more semid_ds's available\n"));
708 error = ENOSPC;
709 goto out;
710 }
711 SEM_PRINTF(("semid %d is available\n", semid));
712 sema[semid].sem_perm._key = key;
713 sema[semid].sem_perm.cuid = kauth_cred_geteuid(cred);
714 sema[semid].sem_perm.uid = kauth_cred_geteuid(cred);
715 sema[semid].sem_perm.cgid = kauth_cred_getegid(cred);
716 sema[semid].sem_perm.gid = kauth_cred_getegid(cred);
717 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
718 sema[semid].sem_perm._seq =
719 (sema[semid].sem_perm._seq + 1) & 0x7fff;
720 sema[semid].sem_nsems = nsems;
721 sema[semid].sem_otime = 0;
722 sema[semid].sem_ctime = time_second;
723 sema[semid]._sem_base = &sem[semtot];
724 semtot += nsems;
725 memset(sema[semid]._sem_base, 0,
726 sizeof(sema[semid]._sem_base[0]) * nsems);
727 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base,
728 &sem[semtot]));
729 } else {
730 SEM_PRINTF(("didn't find it and wasn't asked to create it\n"));
731 error = ENOENT;
732 goto out;
733 }
734
735 found:
736 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
737 out:
738 mutex_exit(&semlock);
739 return (error);
740 }
741
742 #define SMALL_SOPS 8
743
744 int
745 sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval)
746 {
747 /* {
748 syscallarg(int) semid;
749 syscallarg(struct sembuf *) sops;
750 syscallarg(size_t) nsops;
751 } */
752 struct proc *p = l->l_proc;
753 int semid = SCARG(uap, semid), seq;
754 size_t nsops = SCARG(uap, nsops);
755 struct sembuf small_sops[SMALL_SOPS];
756 struct sembuf *sops;
757 struct semid_ds *semaptr;
758 struct sembuf *sopptr = NULL;
759 struct __sem *semptr = NULL;
760 struct sem_undo *suptr = NULL;
761 kauth_cred_t cred = l->l_cred;
762 int i, error;
763 int do_wakeup, do_undos;
764
765 SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, SCARG(uap,sops), nsops));
766
767 if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) {
768 mutex_enter(p->p_lock);
769 p->p_flag |= PK_SYSVSEM;
770 mutex_exit(p->p_lock);
771 }
772
773 restart:
774 if (nsops <= SMALL_SOPS) {
775 sops = small_sops;
776 } else if (nsops <= seminfo.semopm) {
777 sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP);
778 } else {
779 SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n",
780 seminfo.semopm, nsops));
781 return (E2BIG);
782 }
783
784 error = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0]));
785 if (error) {
786 SEM_PRINTF(("error = %d from copyin(%p, %p, %zd)\n", error,
787 SCARG(uap, sops), &sops, nsops * sizeof(sops[0])));
788 if (sops != small_sops)
789 kmem_free(sops, nsops * sizeof(*sops));
790 return error;
791 }
792
793 mutex_enter(&semlock);
794 /* In case of reallocation, we will wait for completion */
795 while (__predict_false(sem_realloc_state))
796 cv_wait(&sem_realloc_cv, &semlock);
797
798 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
799 if (semid < 0 || semid >= seminfo.semmni) {
800 error = EINVAL;
801 goto out;
802 }
803
804 semaptr = &sema[semid];
805 seq = IPCID_TO_SEQ(SCARG(uap, semid));
806 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
807 semaptr->sem_perm._seq != seq) {
808 error = EINVAL;
809 goto out;
810 }
811
812 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) {
813 SEM_PRINTF(("error = %d from ipaccess\n", error));
814 goto out;
815 }
816
817 for (i = 0; i < nsops; i++)
818 if (sops[i].sem_num >= semaptr->sem_nsems) {
819 error = EFBIG;
820 goto out;
821 }
822
823 /*
824 * Loop trying to satisfy the vector of requests.
825 * If we reach a point where we must wait, any requests already
826 * performed are rolled back and we go to sleep until some other
827 * process wakes us up. At this point, we start all over again.
828 *
829 * This ensures that from the perspective of other tasks, a set
830 * of requests is atomic (never partially satisfied).
831 */
832 do_undos = 0;
833
834 for (;;) {
835 do_wakeup = 0;
836
837 for (i = 0; i < nsops; i++) {
838 sopptr = &sops[i];
839 semptr = &semaptr->_sem_base[sopptr->sem_num];
840
841 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, "
842 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n",
843 semaptr, semaptr->_sem_base, semptr,
844 sopptr->sem_num, semptr->semval, sopptr->sem_op,
845 (sopptr->sem_flg & IPC_NOWAIT) ?
846 "nowait" : "wait"));
847
848 if (sopptr->sem_op < 0) {
849 if ((int)(semptr->semval +
850 sopptr->sem_op) < 0) {
851 SEM_PRINTF(("semop: "
852 "can't do it now\n"));
853 break;
854 } else {
855 semptr->semval += sopptr->sem_op;
856 if (semptr->semval == 0 &&
857 semptr->semzcnt > 0)
858 do_wakeup = 1;
859 }
860 if (sopptr->sem_flg & SEM_UNDO)
861 do_undos = 1;
862 } else if (sopptr->sem_op == 0) {
863 if (semptr->semval > 0) {
864 SEM_PRINTF(("semop: not zero now\n"));
865 break;
866 }
867 } else {
868 if (semptr->semncnt > 0)
869 do_wakeup = 1;
870 semptr->semval += sopptr->sem_op;
871 if (sopptr->sem_flg & SEM_UNDO)
872 do_undos = 1;
873 }
874 }
875
876 /*
877 * Did we get through the entire vector?
878 */
879 if (i >= nsops)
880 goto done;
881
882 /*
883 * No ... rollback anything that we've already done
884 */
885 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1));
886 while (i-- > 0)
887 semaptr->_sem_base[sops[i].sem_num].semval -=
888 sops[i].sem_op;
889
890 /*
891 * If the request that we couldn't satisfy has the
892 * NOWAIT flag set then return with EAGAIN.
893 */
894 if (sopptr->sem_flg & IPC_NOWAIT) {
895 error = EAGAIN;
896 goto out;
897 }
898
899 if (sopptr->sem_op == 0)
900 semptr->semzcnt++;
901 else
902 semptr->semncnt++;
903
904 sem_waiters++;
905 SEM_PRINTF(("semop: good night!\n"));
906 error = cv_wait_sig(&semcv[semid], &semlock);
907 SEM_PRINTF(("semop: good morning (error=%d)!\n", error));
908 sem_waiters--;
909
910 /* Notify reallocator, if it is waiting */
911 cv_broadcast(&sem_realloc_cv);
912
913 /*
914 * Make sure that the semaphore still exists
915 */
916 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
917 semaptr->sem_perm._seq != seq) {
918 error = EIDRM;
919 goto out;
920 }
921
922 /*
923 * The semaphore is still alive. Readjust the count of
924 * waiting processes.
925 */
926 semptr = &semaptr->_sem_base[sopptr->sem_num];
927 if (sopptr->sem_op == 0)
928 semptr->semzcnt--;
929 else
930 semptr->semncnt--;
931
932 /* In case of such state, restart the call */
933 if (sem_realloc_state) {
934 mutex_exit(&semlock);
935 goto restart;
936 }
937
938 /* Is it really morning, or was our sleep interrupted? */
939 if (error != 0) {
940 error = EINTR;
941 goto out;
942 }
943 SEM_PRINTF(("semop: good morning!\n"));
944 }
945
946 done:
947 /*
948 * Process any SEM_UNDO requests.
949 */
950 if (do_undos) {
951 for (i = 0; i < nsops; i++) {
952 /*
953 * We only need to deal with SEM_UNDO's for non-zero
954 * op's.
955 */
956 int adjval;
957
958 if ((sops[i].sem_flg & SEM_UNDO) == 0)
959 continue;
960 adjval = sops[i].sem_op;
961 if (adjval == 0)
962 continue;
963 error = semundo_adjust(p, &suptr, semid,
964 sops[i].sem_num, -adjval);
965 if (error == 0)
966 continue;
967
968 /*
969 * Oh-Oh! We ran out of either sem_undo's or undo's.
970 * Rollback the adjustments to this point and then
971 * rollback the semaphore ups and down so we can return
972 * with an error with all structures restored. We
973 * rollback the undo's in the exact reverse order that
974 * we applied them. This guarantees that we won't run
975 * out of space as we roll things back out.
976 */
977 while (i-- > 0) {
978 if ((sops[i].sem_flg & SEM_UNDO) == 0)
979 continue;
980 adjval = sops[i].sem_op;
981 if (adjval == 0)
982 continue;
983 if (semundo_adjust(p, &suptr, semid,
984 sops[i].sem_num, adjval) != 0)
985 panic("semop - can't undo undos");
986 }
987
988 for (i = 0; i < nsops; i++)
989 semaptr->_sem_base[sops[i].sem_num].semval -=
990 sops[i].sem_op;
991
992 SEM_PRINTF(("error = %d from semundo_adjust\n", error));
993 goto out;
994 } /* loop through the sops */
995 } /* if (do_undos) */
996
997 /* We're definitely done - set the sempid's */
998 for (i = 0; i < nsops; i++) {
999 sopptr = &sops[i];
1000 semptr = &semaptr->_sem_base[sopptr->sem_num];
1001 semptr->sempid = p->p_pid;
1002 }
1003
1004 /* Update sem_otime */
1005 semaptr->sem_otime = time_second;
1006
1007 /* Do a wakeup if any semaphore was up'd. */
1008 if (do_wakeup) {
1009 SEM_PRINTF(("semop: doing wakeup\n"));
1010 cv_broadcast(&semcv[semid]);
1011 SEM_PRINTF(("semop: back from wakeup\n"));
1012 }
1013 SEM_PRINTF(("semop: done\n"));
1014 *retval = 0;
1015
1016 out:
1017 mutex_exit(&semlock);
1018 if (sops != small_sops)
1019 kmem_free(sops, nsops * sizeof(*sops));
1020 return error;
1021 }
1022
1023 /*
1024 * Go through the undo structures for this process and apply the
1025 * adjustments to semaphores.
1026 */
1027 /*ARGSUSED*/
1028 void
1029 semexit(struct proc *p, void *v)
1030 {
1031 struct sem_undo *suptr;
1032 struct sem_undo **supptr;
1033
1034 if ((p->p_flag & PK_SYSVSEM) == 0)
1035 return;
1036
1037 mutex_enter(&semlock);
1038
1039 /*
1040 * Go through the chain of undo vectors looking for one
1041 * associated with this process.
1042 */
1043
1044 for (supptr = &semu_list; (suptr = *supptr) != NULL;
1045 supptr = &suptr->un_next) {
1046 if (suptr->un_proc == p)
1047 break;
1048 }
1049
1050 /*
1051 * If there is no undo vector, skip to the end.
1052 */
1053
1054 if (suptr == NULL) {
1055 mutex_exit(&semlock);
1056 return;
1057 }
1058
1059 /*
1060 * We now have an undo vector for this process.
1061 */
1062
1063 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p,
1064 suptr->un_cnt));
1065
1066 /*
1067 * If there are any active undo elements then process them.
1068 */
1069 if (suptr->un_cnt > 0) {
1070 int ix;
1071
1072 for (ix = 0; ix < suptr->un_cnt; ix++) {
1073 int semid = suptr->un_ent[ix].un_id;
1074 int semnum = suptr->un_ent[ix].un_num;
1075 int adjval = suptr->un_ent[ix].un_adjval;
1076 struct semid_ds *semaptr;
1077
1078 semaptr = &sema[semid];
1079 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
1080 panic("semexit - semid not allocated");
1081 if (semnum >= semaptr->sem_nsems)
1082 panic("semexit - semnum out of range");
1083
1084 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; "
1085 "sem=%d\n",
1086 suptr->un_proc, suptr->un_ent[ix].un_id,
1087 suptr->un_ent[ix].un_num,
1088 suptr->un_ent[ix].un_adjval,
1089 semaptr->_sem_base[semnum].semval));
1090
1091 if (adjval < 0 &&
1092 semaptr->_sem_base[semnum].semval < -adjval)
1093 semaptr->_sem_base[semnum].semval = 0;
1094 else
1095 semaptr->_sem_base[semnum].semval += adjval;
1096
1097 cv_broadcast(&semcv[semid]);
1098 SEM_PRINTF(("semexit: back from wakeup\n"));
1099 }
1100 }
1101
1102 /*
1103 * Deallocate the undo vector.
1104 */
1105 SEM_PRINTF(("removing vector\n"));
1106 suptr->un_proc = NULL;
1107 *supptr = suptr->un_next;
1108 mutex_exit(&semlock);
1109 }
1110
1111 /*
1112 * Sysctl initialization and nodes.
1113 */
1114
1115 static int
1116 sysctl_ipc_semmni(SYSCTLFN_ARGS)
1117 {
1118 int newsize, error;
1119 struct sysctlnode node;
1120 node = *rnode;
1121 node.sysctl_data = &newsize;
1122
1123 newsize = seminfo.semmni;
1124 error = sysctl_lookup(SYSCTLFN_CALL(&node));
1125 if (error || newp == NULL)
1126 return error;
1127
1128 return semrealloc(newsize, seminfo.semmns, seminfo.semmnu);
1129 }
1130
1131 static int
1132 sysctl_ipc_semmns(SYSCTLFN_ARGS)
1133 {
1134 int newsize, error;
1135 struct sysctlnode node;
1136 node = *rnode;
1137 node.sysctl_data = &newsize;
1138
1139 newsize = seminfo.semmns;
1140 error = sysctl_lookup(SYSCTLFN_CALL(&node));
1141 if (error || newp == NULL)
1142 return error;
1143
1144 return semrealloc(seminfo.semmni, newsize, seminfo.semmnu);
1145 }
1146
1147 static int
1148 sysctl_ipc_semmnu(SYSCTLFN_ARGS)
1149 {
1150 int newsize, error;
1151 struct sysctlnode node;
1152 node = *rnode;
1153 node.sysctl_data = &newsize;
1154
1155 newsize = seminfo.semmnu;
1156 error = sysctl_lookup(SYSCTLFN_CALL(&node));
1157 if (error || newp == NULL)
1158 return error;
1159
1160 return semrealloc(seminfo.semmni, seminfo.semmns, newsize);
1161 }
1162
1163 SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup")
1164 {
1165 const struct sysctlnode *node = NULL;
1166
1167 sysctl_createv(clog, 0, NULL, NULL,
1168 CTLFLAG_PERMANENT,
1169 CTLTYPE_NODE, "kern", NULL,
1170 NULL, 0, NULL, 0,
1171 CTL_KERN, CTL_EOL);
1172 sysctl_createv(clog, 0, NULL, &node,
1173 CTLFLAG_PERMANENT,
1174 CTLTYPE_NODE, "ipc",
1175 SYSCTL_DESCR("SysV IPC options"),
1176 NULL, 0, NULL, 0,
1177 CTL_KERN, KERN_SYSVIPC, CTL_EOL);
1178
1179 if (node == NULL)
1180 return;
1181
1182 sysctl_createv(clog, 0, &node, NULL,
1183 CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
1184 CTLTYPE_INT, "semmni",
1185 SYSCTL_DESCR("Max number of number of semaphore identifiers"),
1186 sysctl_ipc_semmni, 0, &seminfo.semmni, 0,
1187 CTL_CREATE, CTL_EOL);
1188 sysctl_createv(clog, 0, &node, NULL,
1189 CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
1190 CTLTYPE_INT, "semmns",
1191 SYSCTL_DESCR("Max number of number of semaphores in system"),
1192 sysctl_ipc_semmns, 0, &seminfo.semmns, 0,
1193 CTL_CREATE, CTL_EOL);
1194 sysctl_createv(clog, 0, &node, NULL,
1195 CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
1196 CTLTYPE_INT, "semmnu",
1197 SYSCTL_DESCR("Max number of undo structures in system"),
1198 sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0,
1199 CTL_CREATE, CTL_EOL);
1200 }
Cache object: 99b50202ef003a0be7fd286f07266af5
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