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iso639: Add Montenegrin.
[dragonfly.git] / sys / kern / sysv_sem.c
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1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.69 2004/03/17 09:37:13 cperciva Exp $ */
2
3 /*
4 * Implementation of SVID semaphores
5 *
6 * Author: Daniel Boulet
7 *
8 * This software is provided ``AS IS'' without any warranties of any kind.
9 */
10
11 #include "opt_sysvipc.h"
12
13 #include <sys/param.h>
14 #include <sys/systm.h>
15 #include <sys/sysproto.h>
16 #include <sys/kernel.h>
17 #include <sys/proc.h>
18 #include <sys/sem.h>
19 #include <sys/sysent.h>
20 #include <sys/sysctl.h>
21 #include <sys/malloc.h>
22 #include <sys/jail.h>
23 #include <sys/thread.h>
24
25 #include <sys/thread2.h>
26
27 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
28
29 static void seminit (void *);
30
31 static struct sem_undo *semu_alloc (struct proc *p);
32 static int semundo_adjust (struct proc *p, int semid, int semnum, int adjval);
33 static void semundo_clear (int semid, int semnum);
34
35 static struct lwkt_token semu_token = LWKT_TOKEN_INITIALIZER(semu_token);
36 static int semtot = 0;
37 static struct semid_pool *sema; /* semaphore id pool */
38 static TAILQ_HEAD(, sem_undo) semu_list = TAILQ_HEAD_INITIALIZER(semu_list);
39 static struct lock sema_lk;
40
41 struct sem {
42 u_short semval; /* semaphore value */
43 pid_t sempid; /* pid of last operation */
44 u_short semncnt; /* # awaiting semval > cval */
45 u_short semzcnt; /* # awaiting semval = 0 */
46 };
47
48 /*
49 * Undo structure (one per process)
50 */
51 struct sem_undo {
52 TAILQ_ENTRY(sem_undo) un_entry; /* linked list for semundo_clear() */
53 struct proc *un_proc; /* owner of this structure */
54 int un_refs; /* prevent unlink/kfree */
55 short un_cnt; /* # of active entries */
56 short un_unused;
57 struct undo {
58 short un_adjval; /* adjust on exit values */
59 short un_num; /* semaphore # */
60 int un_id; /* semid */
61 } un_ent[1]; /* undo entries */
62 };
63
64 /*
65 * Configuration parameters
66 */
67 #ifndef SEMMNI
68 #define SEMMNI 1024 /* # of semaphore identifiers */
69 #endif
70 #ifndef SEMMNS
71 #define SEMMNS 32767 /* # of semaphores in system */
72 #endif
73 #ifndef SEMUME
74 #define SEMUME 25 /* max # of undo entries per process */
75 #endif
76 #ifndef SEMMNU
77 #define SEMMNU 1024 /* # of undo structures in system */
78 /* NO LONGER USED */
79 #endif
80
81 /* shouldn't need tuning */
82 #ifndef SEMMAP
83 #define SEMMAP 128 /* # of entries in semaphore map */
84 #endif
85 #ifndef SEMMSL
86 #define SEMMSL SEMMNS /* max # of semaphores per id */
87 #endif
88 #ifndef SEMOPM
89 #define SEMOPM 100 /* max # of operations per semop call */
90 #endif
91
92 #define SEMVMX 32767 /* semaphore maximum value */
93 #define SEMAEM 16384 /* adjust on exit max value */
94
95 /*
96 * Due to the way semaphore memory is allocated, we have to ensure that
97 * SEMUSZ is properly aligned.
98 */
99
100 #define SEM_ALIGN(bytes) roundup2(bytes, sizeof(long))
101
102 /* actual size of an undo structure */
103 #define SEMUSZ(nent) SEM_ALIGN(offsetof(struct sem_undo, un_ent[nent]))
104
105 /*
106 * semaphore info struct
107 */
108 struct seminfo seminfo = {
109 SEMMAP, /* # of entries in semaphore map */
110 SEMMNI, /* # of semaphore identifiers */
111 SEMMNS, /* # of semaphores in system */
112 SEMMNU, /* # of undo structures in system */
113 SEMMSL, /* max # of semaphores per id */
114 SEMOPM, /* max # of operations per semop call */
115 SEMUME, /* max # of undo entries per process */
116 SEMUSZ(SEMUME), /* size in bytes of undo structure */
117 SEMVMX, /* semaphore maximum value */
118 SEMAEM /* adjust on exit max value */
119 };
120
121 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap);
122 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni);
123 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns);
124 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu);
125 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl);
126 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm);
127 TUNABLE_INT("kern.ipc.semume", &seminfo.semume);
128 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz);
129 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx);
130 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem);
131
132 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0,
133 "Number of entries in semaphore map");
134 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0,
135 "Number of semaphore identifiers");
136 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0,
137 "Total number of semaphores");
138 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0,
139 "Total number of undo structures");
140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0,
141 "Max number of semaphores per id");
142 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0,
143 "Max number of operations per semop call");
144 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0,
145 "Max number of undo entries per process");
146 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0,
147 "Size in bytes of undo structure");
148 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0,
149 "Semaphore maximum value");
150 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0,
151 "Adjust on exit max value");
152
153 #if 0
154 RO seminfo.semmap /* SEMMAP unused */
155 RO seminfo.semmni
156 RO seminfo.semmns
157 RO seminfo.semmnu /* undo entries per system */
158 RW seminfo.semmsl
159 RO seminfo.semopm /* SEMOPM unused */
160 RO seminfo.semume
161 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */
162 RO seminfo.semvmx /* SEMVMX unused - user param */
163 RO seminfo.semaem /* SEMAEM unused - user param */
164 #endif
165
166 static void
167 seminit(void *dummy)
168 {
169 int i;
170
171 sema = kmalloc(sizeof(struct semid_pool) * seminfo.semmni,
172 M_SEM, M_WAITOK | M_ZERO);
173
174 lockinit(&sema_lk, "semglb", 0, 0);
175 for (i = 0; i < seminfo.semmni; i++) {
176 struct semid_pool *semaptr = &sema[i];
177
178 lockinit(&semaptr->lk, "semary", 0, 0);
179 semaptr->ds.sem_base = NULL;
180 semaptr->ds.sem_perm.mode = 0;
181 }
182 }
183 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL);
184
185 /*
186 * Allocate a new sem_undo structure for a process
187 * (returns ptr to structure or NULL if no more room)
188 */
189 static struct sem_undo *
190 semu_alloc(struct proc *p)
191 {
192 struct sem_undo *semu;
193
194 /*
195 * Allocate the semu structure and associate it with the process,
196 * as necessary.
197 */
198 while ((semu = p->p_sem_undo) == NULL) {
199 semu = kmalloc(SEMUSZ(seminfo.semume), M_SEM,
200 M_WAITOK | M_ZERO);
201 lwkt_gettoken(&semu_token);
202 lwkt_gettoken(&p->p_token);
203 if (p->p_sem_undo == NULL) {
204 p->p_sem_undo = semu;
205 p->p_flags |= P_SYSVSEM;
206 semu->un_proc = p;
207 TAILQ_INSERT_TAIL(&semu_list, semu, un_entry);
208 } else {
209 kfree(semu, M_SEM);
210 }
211 lwkt_reltoken(&p->p_token);
212 lwkt_reltoken(&semu_token);
213 }
214 return(semu);
215 }
216
217 /*
218 * Adjust a particular entry for a particular proc
219 */
220 static int
221 semundo_adjust(struct proc *p, int semid, int semnum, int adjval)
222 {
223 struct sem_undo *suptr;
224 struct undo *sunptr;
225 int i;
226 int error = 0;
227
228 /*
229 * Look for and remember the sem_undo if the caller doesn't
230 * provide it.
231 */
232 suptr = semu_alloc(p);
233 lwkt_gettoken(&p->p_token);
234
235 /*
236 * Look for the requested entry and adjust it (delete if adjval becomes
237 * 0).
238 */
239 sunptr = &suptr->un_ent[0];
240 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
241 if (sunptr->un_id != semid || sunptr->un_num != semnum)
242 continue;
243 if (adjval == 0)
244 sunptr->un_adjval = 0;
245 else
246 sunptr->un_adjval += adjval;
247 if (sunptr->un_adjval == 0) {
248 suptr->un_cnt--;
249 if (i < suptr->un_cnt)
250 suptr->un_ent[i] = suptr->un_ent[suptr->un_cnt];
251 }
252 goto done;
253 }
254
255 /* Didn't find the right entry - create it */
256 if (adjval == 0)
257 goto done;
258 if (suptr->un_cnt != seminfo.semume) {
259 sunptr = &suptr->un_ent[suptr->un_cnt];
260 suptr->un_cnt++;
261 sunptr->un_adjval = adjval;
262 sunptr->un_id = semid;
263 sunptr->un_num = semnum;
264 } else {
265 error = EINVAL;
266 }
267 done:
268 lwkt_reltoken(&p->p_token);
269
270 return (error);
271 }
272
273 /*
274 * This is rather expensive
275 */
276 static void
277 semundo_clear(int semid, int semnum)
278 {
279 struct proc *p;
280 struct sem_undo *suptr;
281 struct sem_undo *sunext;
282 struct undo *sunptr;
283 int i;
284
285 lwkt_gettoken(&semu_token);
286 sunext = TAILQ_FIRST(&semu_list);
287 while ((suptr = sunext) != NULL) {
288 if ((p = suptr->un_proc) == NULL) {
289 suptr = TAILQ_NEXT(suptr, un_entry);
290 continue;
291 }
292 ++suptr->un_refs;
293 PHOLD(p);
294 lwkt_gettoken(&p->p_token);
295
296 sunptr = &suptr->un_ent[0];
297 i = 0;
298
299 while (i < suptr->un_cnt) {
300 if (sunptr->un_id == semid) {
301 if (semnum == -1 || sunptr->un_num == semnum) {
302 suptr->un_cnt--;
303 if (i < suptr->un_cnt) {
304 suptr->un_ent[i] =
305 suptr->un_ent[suptr->un_cnt];
306 /*
307 * do not increment i
308 * or sunptr after copydown.
309 */
310 continue;
311 }
312 }
313 if (semnum != -1)
314 break;
315 }
316 ++i;
317 ++sunptr;
318 }
319
320 lwkt_reltoken(&p->p_token);
321 PRELE(p);
322
323 /*
324 * Handle deletion races
325 */
326 sunext = TAILQ_NEXT(suptr, un_entry);
327 if (--suptr->un_refs == 0 && suptr->un_proc == NULL) {
328 KKASSERT(suptr->un_cnt == 0);
329 TAILQ_REMOVE(&semu_list, suptr, un_entry);
330 kfree(suptr, M_SEM);
331 }
332 }
333 lwkt_reltoken(&semu_token);
334 }
335
336 /*
337 * Note that the user-mode half of this passes a union, not a pointer
338 *
339 * MPALMOSTSAFE
340 */
341 int
342 sys___semctl(struct __semctl_args *uap)
343 {
344 struct thread *td = curthread;
345 int semid = uap->semid;
346 int semnum = uap->semnum;
347 int cmd = uap->cmd;
348 union semun *arg = uap->arg;
349 union semun real_arg;
350 struct ucred *cred = td->td_ucred;
351 int i, rval, eval;
352 struct semid_ds sbuf;
353 struct semid_pool *semaptr;
354 struct sem *semptr;
355
356 #ifdef SEM_DEBUG
357 kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
358 #endif
359
360 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
361 return (ENOSYS);
362
363 semid = IPCID_TO_IX(semid);
364 if (semid < 0 || semid >= seminfo.semmni) {
365 return(EINVAL);
366 }
367 semaptr = &sema[semid];
368 lockmgr(&semaptr->lk, LK_EXCLUSIVE);
369
370 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0 ||
371 semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
372 lockmgr(&semaptr->lk, LK_RELEASE);
373 return(EINVAL);
374 }
375
376 eval = 0;
377 rval = 0;
378
379 switch (cmd) {
380 case IPC_RMID:
381 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_M);
382 if (eval != 0)
383 break;
384 semaptr->ds.sem_perm.cuid = cred->cr_uid;
385 semaptr->ds.sem_perm.uid = cred->cr_uid;
386
387 /*
388 * NOTE: Nobody will be waiting on the semaphores since
389 * we have an exclusive lock on semaptr->lk).
390 */
391 lockmgr(&sema_lk, LK_EXCLUSIVE);
392 semtot -= semaptr->ds.sem_nsems;
393 kfree(semaptr->ds.sem_base, M_SEM);
394 semaptr->ds.sem_base = NULL;
395 semaptr->ds.sem_perm.mode = 0; /* clears SEM_ALLOC */
396 lockmgr(&sema_lk, LK_RELEASE);
397
398 semundo_clear(semid, -1);
399 break;
400
401 case IPC_SET:
402 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_M);
403 if (eval)
404 break;
405 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
406 break;
407 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
408 sizeof(sbuf))) != 0) {
409 break;
410 }
411 semaptr->ds.sem_perm.uid = sbuf.sem_perm.uid;
412 semaptr->ds.sem_perm.gid = sbuf.sem_perm.gid;
413 semaptr->ds.sem_perm.mode =
414 (semaptr->ds.sem_perm.mode & ~0777) |
415 (sbuf.sem_perm.mode & 0777);
416 semaptr->ds.sem_ctime = time_second;
417 break;
418
419 case IPC_STAT:
420 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
421 if (eval)
422 break;
423 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
424 break;
425 eval = copyout(&semaptr->ds, real_arg.buf,
426 sizeof(struct semid_ds));
427 break;
428 case SEM_STAT:
429 /*
430 * For this command we assume semid is an array index
431 * rather than an IPC id. However, the conversion is
432 * just a mask so just validate that the passed-in semid
433 * matches the masked semid.
434 */
435 if (uap->semid != semid) {
436 eval = EINVAL;
437 break;
438 }
439 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
440 if (eval)
441 break;
442 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
443 break;
444 eval = copyout(&semaptr->ds, real_arg.buf,
445 sizeof(struct semid_ds));
446 rval = IXSEQ_TO_IPCID(semid, semaptr->ds.sem_perm);
447 break;
448
449 case GETNCNT:
450 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
451 if (eval)
452 break;
453 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) {
454 eval = EINVAL;
455 break;
456 }
457 rval = semaptr->ds.sem_base[semnum].semncnt;
458 break;
459
460 case GETPID:
461 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
462 if (eval)
463 break;
464 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) {
465 eval = EINVAL;
466 break;
467 }
468 rval = semaptr->ds.sem_base[semnum].sempid;
469 break;
470
471 case GETVAL:
472 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
473 if (eval)
474 break;
475 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) {
476 eval = EINVAL;
477 break;
478 }
479 rval = semaptr->ds.sem_base[semnum].semval;
480 break;
481
482 case GETALL:
483 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
484 if (eval)
485 break;
486 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
487 break;
488 for (i = 0; i < semaptr->ds.sem_nsems; i++) {
489 eval = copyout(&semaptr->ds.sem_base[i].semval,
490 &real_arg.array[i],
491 sizeof(real_arg.array[0]));
492 if (eval)
493 break;
494 }
495 break;
496
497 case GETZCNT:
498 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R);
499 if (eval)
500 break;
501 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) {
502 eval = EINVAL;
503 break;
504 }
505 rval = semaptr->ds.sem_base[semnum].semzcnt;
506 break;
507
508 case SETVAL:
509 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W);
510 if (eval)
511 break;
512 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) {
513 eval = EINVAL;
514 break;
515 }
516 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
517 break;
518
519 /*
520 * Because we hold semaptr->lk exclusively we can safely
521 * modify any semptr content without acquiring its token.
522 */
523 semptr = &semaptr->ds.sem_base[semnum];
524 semptr->semval = real_arg.val;
525 semundo_clear(semid, semnum);
526 if (semptr->semzcnt || semptr->semncnt)
527 wakeup(semptr);
528 break;
529
530 case SETALL:
531 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W);
532 if (eval)
533 break;
534 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
535 break;
536 /*
537 * Because we hold semaptr->lk exclusively we can safely
538 * modify any semptr content without acquiring its token.
539 */
540 for (i = 0; i < semaptr->ds.sem_nsems; i++) {
541 semptr = &semaptr->ds.sem_base[i];
542 eval = copyin(&real_arg.array[i],
543 (caddr_t)&semptr->semval,
544 sizeof(real_arg.array[0]));
545 if (semptr->semzcnt || semptr->semncnt)
546 wakeup(semptr);
547 if (eval != 0)
548 break;
549 }
550 semundo_clear(semid, -1);
551 break;
552
553 default:
554 eval = EINVAL;
555 break;
556 }
557 lockmgr(&semaptr->lk, LK_RELEASE);
558
559 if (eval == 0)
560 uap->sysmsg_result = rval;
561 return(eval);
562 }
563
564 /*
565 * MPALMOSTSAFE
566 */
567 int
568 sys_semget(struct semget_args *uap)
569 {
570 struct thread *td = curthread;
571 int semid, eval;
572 int key = uap->key;
573 int nsems = uap->nsems;
574 int semflg = uap->semflg;
575 struct ucred *cred = td->td_ucred;
576
577 #ifdef SEM_DEBUG
578 kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
579 #endif
580
581 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
582 return (ENOSYS);
583
584 eval = 0;
585
586 if (key != IPC_PRIVATE) {
587 for (semid = 0; semid < seminfo.semmni; semid++) {
588 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0 ||
589 sema[semid].ds.sem_perm.key != key) {
590 continue;
591 }
592 lockmgr(&sema[semid].lk, LK_EXCLUSIVE);
593 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0 ||
594 sema[semid].ds.sem_perm.key != key) {
595 lockmgr(&sema[semid].lk, LK_RELEASE);
596 continue;
597 }
598 break;
599 }
600 if (semid < seminfo.semmni) {
601 /* sema[semid].lk still locked from above */
602 #ifdef SEM_DEBUG
603 kprintf("found public key\n");
604 #endif
605 if ((eval = ipcperm(td->td_proc,
606 &sema[semid].ds.sem_perm,
607 semflg & 0700))) {
608 lockmgr(&sema[semid].lk, LK_RELEASE);
609 goto done;
610 }
611 if (nsems > 0 && sema[semid].ds.sem_nsems < nsems) {
612 #ifdef SEM_DEBUG
613 kprintf("too small\n");
614 #endif
615 eval = EINVAL;
616 lockmgr(&sema[semid].lk, LK_RELEASE);
617 goto done;
618 }
619 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
620 #ifdef SEM_DEBUG
621 kprintf("not exclusive\n");
622 #endif
623 eval = EEXIST;
624 lockmgr(&sema[semid].lk, LK_RELEASE);
625 goto done;
626 }
627
628 /*
629 * Return this one.
630 */
631 lockmgr(&sema[semid].lk, LK_RELEASE);
632 goto done;
633 }
634 }
635
636 #ifdef SEM_DEBUG
637 kprintf("need to allocate the semid_ds\n");
638 #endif
639 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
640 if (nsems <= 0 || nsems > seminfo.semmsl) {
641 #ifdef SEM_DEBUG
642 kprintf("nsems out of range (0<%d<=%d)\n",
643 nsems, seminfo.semmsl);
644 #endif
645 eval = EINVAL;
646 goto done;
647 }
648
649 /*
650 * SEM_ALLOC flag cannot be set unless sema_lk is locked.
651 * semtot field also protected by sema_lk.
652 */
653 lockmgr(&sema_lk, LK_EXCLUSIVE);
654 if (nsems > seminfo.semmns - semtot) {
655 #ifdef SEM_DEBUG
656 kprintf("not enough semaphores left "
657 "(need %d, got %d)\n",
658 nsems, seminfo.semmns - semtot);
659 #endif
660 eval = ENOSPC;
661 lockmgr(&sema_lk, LK_RELEASE);
662 goto done;
663 }
664 for (semid = 0; semid < seminfo.semmni; semid++) {
665 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0)
666 break;
667 }
668 if (semid == seminfo.semmni) {
669 #ifdef SEM_DEBUG
670 kprintf("no more semid_ds's available\n");
671 #endif
672 eval = ENOSPC;
673 lockmgr(&sema_lk, LK_RELEASE);
674 goto done;
675 }
676 #ifdef SEM_DEBUG
677 kprintf("semid %d is available\n", semid);
678 #endif
679 lockmgr(&sema[semid].lk, LK_EXCLUSIVE);
680 sema[semid].ds.sem_perm.key = key;
681 sema[semid].ds.sem_perm.cuid = cred->cr_uid;
682 sema[semid].ds.sem_perm.uid = cred->cr_uid;
683 sema[semid].ds.sem_perm.cgid = cred->cr_gid;
684 sema[semid].ds.sem_perm.gid = cred->cr_gid;
685 sema[semid].ds.sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
686 sema[semid].ds.sem_perm.seq =
687 (sema[semid].ds.sem_perm.seq + 1) & 0x7fff;
688 sema[semid].ds.sem_nsems = nsems;
689 sema[semid].ds.sem_otime = 0;
690 sema[semid].ds.sem_ctime = time_second;
691 sema[semid].ds.sem_base = kmalloc(sizeof(struct sem) * nsems,
692 M_SEM, M_WAITOK|M_ZERO);
693 semtot += nsems;
694 ++sema[semid].gen;
695 lockmgr(&sema[semid].lk, LK_RELEASE);
696 lockmgr(&sema_lk, LK_RELEASE);
697 #ifdef SEM_DEBUG
698 kprintf("sembase = 0x%x, next = 0x%x\n",
699 sema[semid].ds.sem_base, &sem[semtot]);
700 #endif
701 /* eval == 0 */
702 } else {
703 #ifdef SEM_DEBUG
704 kprintf("didn't find it and wasn't asked to create it\n");
705 #endif
706 eval = ENOENT;
707 }
708
709 done:
710 if (eval == 0) {
711 uap->sysmsg_result =
712 IXSEQ_TO_IPCID(semid, sema[semid].ds.sem_perm);
713 }
714 return(eval);
715 }
716
717 /*
718 * MPSAFE
719 */
720 int
721 sys_semop(struct semop_args *uap)
722 {
723 struct thread *td = curthread;
724 int semid = uap->semid;
725 u_int nsops = uap->nsops;
726 struct sembuf sops[MAX_SOPS];
727 struct semid_pool *semaptr;
728 struct sembuf *sopptr;
729 struct sem *semptr;
730 struct sem *xsemptr;
731 int i, j, eval;
732 int do_undos;
733
734 #ifdef SEM_DEBUG
735 kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
736 #endif
737 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
738 return (ENOSYS);
739
740 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
741
742 if (semid < 0 || semid >= seminfo.semmni) {
743 eval = EINVAL;
744 goto done2;
745 }
746
747 wakeup_start_delayed();
748 semaptr = &sema[semid];
749 lockmgr(&semaptr->lk, LK_SHARED);
750
751 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0) {
752 eval = EINVAL;
753 goto done;
754 }
755 if (semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
756 eval = EINVAL;
757 goto done;
758 }
759
760 if ((eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W))) {
761 #ifdef SEM_DEBUG
762 kprintf("eval = %d from ipaccess\n", eval);
763 #endif
764 goto done;
765 }
766
767 if (nsops > MAX_SOPS) {
768 #ifdef SEM_DEBUG
769 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops);
770 #endif
771 eval = E2BIG;
772 goto done;
773 }
774
775 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
776 #ifdef SEM_DEBUG
777 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval,
778 uap->sops, &sops, nsops * sizeof(sops[0]));
779 #endif
780 goto done;
781 }
782
783 /*
784 * Loop trying to satisfy the vector of requests.
785 * If we reach a point where we must wait, any requests already
786 * performed are rolled back and we go to sleep until some other
787 * process wakes us up. At this point, we start all over again.
788 *
789 * This ensures that from the perspective of other tasks, a set
790 * of requests is atomic (never partially satisfied).
791 */
792 do_undos = 0;
793
794 for (;;) {
795 long gen;
796
797 semptr = NULL;
798
799 for (i = 0; i < nsops; i++) {
800 sopptr = &sops[i];
801
802 if (sopptr->sem_num >= semaptr->ds.sem_nsems) {
803 eval = EFBIG;
804 goto done;
805 }
806
807 semptr = &semaptr->ds.sem_base[sopptr->sem_num];
808 lwkt_getpooltoken(semptr);
809
810 #ifdef SEM_DEBUG
811 kprintf("semop: semaptr=%x, sem_base=%x, semptr=%x, "
812 "sem[%d]=%d : op=%d, flag=%s\n",
813 semaptr, semaptr->ds.sem_base, semptr,
814 sopptr->sem_num, semptr->semval, sopptr->sem_op,
815 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
816 #endif
817
818 if (sopptr->sem_op < 0) {
819 if (semptr->semval + sopptr->sem_op < 0) {
820 #ifdef SEM_DEBUG
821 kprintf("semop: can't do it now\n");
822 #endif
823 break;
824 } else {
825 semptr->semval += sopptr->sem_op;
826 if (semptr->semval == 0 &&
827 semptr->semzcnt > 0) {
828 wakeup(semptr);
829 }
830 }
831 if (sopptr->sem_flg & SEM_UNDO)
832 do_undos = 1;
833 } else if (sopptr->sem_op == 0) {
834 if (semptr->semval > 0) {
835 #ifdef SEM_DEBUG
836 kprintf("semop: not zero now\n");
837 #endif
838 break;
839 }
840 } else {
841 semptr->semval += sopptr->sem_op;
842 if (sopptr->sem_flg & SEM_UNDO)
843 do_undos = 1;
844 if (semptr->semncnt > 0)
845 wakeup(semptr);
846 }
847 lwkt_relpooltoken(semptr);
848 }
849
850 /*
851 * Did we get through the entire vector?
852 */
853 if (i >= nsops)
854 goto donex;
855
856 /*
857 * No, protect the semaphore request which also flags that
858 * a wakeup is needed, then release semptr since we know
859 * another process is likely going to need to access it
860 * soon.
861 */
862 if (sopptr->sem_op == 0)
863 semptr->semzcnt++;
864 else
865 semptr->semncnt++;
866 tsleep_interlock(semptr, PCATCH);
867 lwkt_relpooltoken(semptr);
868
869 /*
870 * Rollback the semaphores we had acquired.
871 */
872 #ifdef SEM_DEBUG
873 kprintf("semop: rollback 0 through %d\n", i-1);
874 #endif
875 for (j = 0; j < i; j++) {
876 xsemptr = &semaptr->ds.sem_base[sops[j].sem_num];
877 lwkt_getpooltoken(xsemptr);
878 xsemptr->semval -= sops[j].sem_op;
879 if (xsemptr->semval == 0 && xsemptr->semzcnt > 0)
880 wakeup(xsemptr);
881 if (xsemptr->semval <= 0 && xsemptr->semncnt > 0)
882 wakeup(xsemptr);
883 lwkt_relpooltoken(xsemptr);
884 }
885
886 /*
887 * If the request that we couldn't satisfy has the
888 * NOWAIT flag set then return with EAGAIN.
889 */
890 if (sopptr->sem_flg & IPC_NOWAIT) {
891 eval = EAGAIN;
892 goto done;
893 }
894
895 /*
896 * Release semaptr->lk while sleeping, allowing other
897 * semops (like SETVAL, SETALL, etc), which require an
898 * exclusive lock and might wake us up.
899 *
900 * Reload and recheck the validity of semaptr on return.
901 * Note that semptr itself might have changed too, but
902 * we've already interlocked for semptr and that is what
903 * will be woken up if it wakes up the tsleep on a MP
904 * race.
905 *
906 * gen protects against destroy/re-create races where the
907 * creds match.
908 */
909 #ifdef SEM_DEBUG
910 kprintf("semop: good night!\n");
911 #endif
912 gen = semaptr->gen;
913 lockmgr(&semaptr->lk, LK_RELEASE);
914 eval = tsleep(semptr, PCATCH | PINTERLOCKED, "semwait", hz);
915 lockmgr(&semaptr->lk, LK_SHARED);
916 #ifdef SEM_DEBUG
917 kprintf("semop: good morning (eval=%d)!\n", eval);
918 #endif
919
920 /* return code is checked below, after sem[nz]cnt-- */
921
922 /*
923 * Make sure that the semaphore still exists
924 */
925 if (semaptr->gen != gen ||
926 (semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0 ||
927 semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
928 eval = EIDRM;
929 goto done;
930 }
931
932 /*
933 * The semaphore is still alive. Readjust the count of
934 * waiting processes.
935 */
936 semptr = &semaptr->ds.sem_base[sopptr->sem_num];
937 lwkt_getpooltoken(semptr);
938 if (sopptr->sem_op == 0)
939 semptr->semzcnt--;
940 else
941 semptr->semncnt--;
942 lwkt_relpooltoken(semptr);
943
944 /*
945 * Is it really morning, or was our sleep interrupted?
946 * (Delayed check of tsleep() return code because we
947 * need to decrement sem[nz]cnt either way.)
948 */
949 if (eval) {
950 eval = EINTR;
951 goto done;
952 }
953 #ifdef SEM_DEBUG
954 kprintf("semop: good morning!\n");
955 #endif
956 /* RETRY LOOP */
957 }
958
959 donex:
960 /*
961 * Process any SEM_UNDO requests.
962 */
963 if (do_undos) {
964 for (i = 0; i < nsops; i++) {
965 /*
966 * We only need to deal with SEM_UNDO's for non-zero
967 * op's.
968 */
969 int adjval;
970
971 if ((sops[i].sem_flg & SEM_UNDO) == 0)
972 continue;
973 adjval = sops[i].sem_op;
974 if (adjval == 0)
975 continue;
976 eval = semundo_adjust(td->td_proc, semid,
977 sops[i].sem_num, -adjval);
978 if (eval == 0)
979 continue;
980
981 /*
982 * Oh-Oh! We ran out of either sem_undo's or undo's.
983 * Rollback the adjustments to this point and then
984 * rollback the semaphore ups and down so we can return
985 * with an error with all structures restored. We
986 * rollback the undo's in the exact reverse order that
987 * we applied them. This guarantees that we won't run
988 * out of space as we roll things back out.
989 */
990 for (j = i - 1; j >= 0; j--) {
991 if ((sops[j].sem_flg & SEM_UNDO) == 0)
992 continue;
993 adjval = sops[j].sem_op;
994 if (adjval == 0)
995 continue;
996 if (semundo_adjust(td->td_proc, semid,
997 sops[j].sem_num, adjval) != 0)
998 panic("semop - can't undo undos");
999 }
1000
1001 for (j = 0; j < nsops; j++) {
1002 xsemptr = &semaptr->ds.sem_base[
1003 sops[j].sem_num];
1004 lwkt_getpooltoken(xsemptr);
1005 xsemptr->semval -= sops[j].sem_op;
1006 if (xsemptr->semval == 0 &&
1007 xsemptr->semzcnt > 0)
1008 wakeup(xsemptr);
1009 if (xsemptr->semval <= 0 &&
1010 xsemptr->semncnt > 0)
1011 wakeup(xsemptr);
1012 lwkt_relpooltoken(xsemptr);
1013 }
1014
1015 #ifdef SEM_DEBUG
1016 kprintf("eval = %d from semundo_adjust\n", eval);
1017 #endif
1018 goto done;
1019 } /* loop through the sops */
1020 } /* if (do_undos) */
1021
1022 /* We're definitely done - set the sempid's */
1023 for (i = 0; i < nsops; i++) {
1024 sopptr = &sops[i];
1025 semptr = &semaptr->ds.sem_base[sopptr->sem_num];
1026 lwkt_getpooltoken(semptr);
1027 semptr->sempid = td->td_proc->p_pid;
1028 lwkt_relpooltoken(semptr);
1029 }
1030
1031 /* Do a wakeup if any semaphore was up'd. */
1032 #ifdef SEM_DEBUG
1033 kprintf("semop: done\n");
1034 #endif
1035 uap->sysmsg_result = 0;
1036 eval = 0;
1037 done:
1038 lockmgr(&semaptr->lk, LK_RELEASE);
1039 wakeup_end_delayed();
1040 done2:
1041 return(eval);
1042 }
1043
1044 /*
1045 * Go through the undo structures for this process and apply the adjustments to
1046 * semaphores.
1047 *
1048 * (p->p_token is held by the caller)
1049 */
1050 void
1051 semexit(struct proc *p)
1052 {
1053 struct sem_undo *suptr;
1054 struct sem *semptr;
1055
1056 /*
1057 * We're getting a global token, don't do it if we couldn't
1058 * possibly have any semaphores.
1059 */
1060 if ((p->p_flags & P_SYSVSEM) == 0)
1061 return;
1062 suptr = p->p_sem_undo;
1063 KKASSERT(suptr != NULL);
1064
1065 /*
1066 * Disconnect suptr from the process and increment un_refs to
1067 * prevent anyone else from being able to destroy the structure.
1068 * Do not remove it from the linked list until after we are through
1069 * scanning it as other semaphore calls might still effect it.
1070 */
1071 lwkt_gettoken(&semu_token);
1072 p->p_sem_undo = NULL;
1073 p->p_flags &= ~P_SYSVSEM;
1074 suptr->un_proc = NULL;
1075 ++suptr->un_refs;
1076 lwkt_reltoken(&semu_token);
1077
1078 while (suptr->un_cnt) {
1079 struct semid_pool *semaptr;
1080 int semid;
1081 int semnum;
1082 int adjval;
1083 int ix;
1084
1085 /*
1086 * These values are stable because we hold p->p_token.
1087 * However, they can get ripped out from under us when
1088 * we block or obtain other tokens so we have to re-check.
1089 */
1090 ix = suptr->un_cnt - 1;
1091 semid = suptr->un_ent[ix].un_id;
1092 semnum = suptr->un_ent[ix].un_num;
1093 adjval = suptr->un_ent[ix].un_adjval;
1094
1095 semaptr = &sema[semid];
1096
1097 /*
1098 * Recheck after locking, then execute the undo
1099 * operation. semptr remains valid due to the
1100 * semaptr->lk.
1101 */
1102 lockmgr(&semaptr->lk, LK_SHARED);
1103 semptr = &semaptr->ds.sem_base[semnum];
1104 lwkt_getpooltoken(semptr);
1105
1106 if (ix == suptr->un_cnt - 1 &&
1107 semid == suptr->un_ent[ix].un_id &&
1108 semnum == suptr->un_ent[ix].un_num &&
1109 adjval == suptr->un_ent[ix].un_adjval) {
1110 /*
1111 * Only do assertions when we aren't in a SMP race.
1112 */
1113 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0)
1114 panic("semexit - semid not allocated");
1115 if (semnum >= semaptr->ds.sem_nsems)
1116 panic("semexit - semnum out of range");
1117 --suptr->un_cnt;
1118
1119 if (adjval < 0) {
1120 if (semptr->semval < -adjval)
1121 semptr->semval = 0;
1122 else
1123 semptr->semval += adjval;
1124 } else {
1125 semptr->semval += adjval;
1126 }
1127 wakeup(semptr);
1128 }
1129 lwkt_relpooltoken(semptr);
1130 lockmgr(&semaptr->lk, LK_RELEASE);
1131 }
1132
1133 /*
1134 * Final cleanup, remove from the list and deallocate on the
1135 * last ref only.
1136 */
1137 lwkt_gettoken(&semu_token);
1138 if (--suptr->un_refs == 0) {
1139 TAILQ_REMOVE(&semu_list, suptr, un_entry);
1140 KKASSERT(suptr->un_cnt == 0);
1141 kfree(suptr, M_SEM);
1142 }
1143 lwkt_reltoken(&semu_token);
1144 }
DragonFly BSD