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bridge.4: Add missing .Bl/.El
[dragonfly.git] / sys / kern / sysv_sem.c
blob6799334bffe6de75d3c23ecd9e06a1253cdc6cc1
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
24 #include <sys/mplock2.h>
25
26 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
27
28 static void seminit (void *);
29
30 static struct sem_undo *semu_alloc (struct proc *p);
31 static int semundo_adjust (struct proc *p, struct sem_undo **supptr,
32 int semid, int semnum, int adjval);
33 static void semundo_clear (int semid, int semnum);
34
35 /* XXX casting to (sy_call_t *) is bogus, as usual. */
36 static sy_call_t *semcalls[] = {
37 (sy_call_t *)sys___semctl, (sy_call_t *)sys_semget,
38 (sy_call_t *)sys_semop
39 };
40
41 static int semtot = 0;
42 static struct semid_ds *sema; /* semaphore id pool */
43 static struct sem *sem; /* semaphore pool */
44 static struct sem_undo *semu_list; /* list of active undo structures */
45 static int *semu; /* undo structure pool */
46
47 struct sem {
48 u_short semval; /* semaphore value */
49 pid_t sempid; /* pid of last operation */
50 u_short semncnt; /* # awaiting semval > cval */
51 u_short semzcnt; /* # awaiting semval = 0 */
52 };
53
54 /*
55 * Undo structure (one per process)
56 */
57 struct sem_undo {
58 struct sem_undo *un_next; /* ptr to next active undo structure */
59 struct proc *un_proc; /* owner of this structure */
60 short un_cnt; /* # of active entries */
61 struct undo {
62 short un_adjval; /* adjust on exit values */
63 short un_num; /* semaphore # */
64 int un_id; /* semid */
65 } un_ent[1]; /* undo entries */
66 };
67
68 /*
69 * Configuration parameters
70 */
71 #ifndef SEMMNI
72 #define SEMMNI 10 /* # of semaphore identifiers */
73 #endif
74 #ifndef SEMMNS
75 #define SEMMNS 60 /* # of semaphores in system */
76 #endif
77 #ifndef SEMUME
78 #define SEMUME 10 /* max # of undo entries per process */
79 #endif
80 #ifndef SEMMNU
81 #define SEMMNU 30 /* # of undo structures in system */
82 #endif
83
84 /* shouldn't need tuning */
85 #ifndef SEMMAP
86 #define SEMMAP 30 /* # of entries in semaphore map */
87 #endif
88 #ifndef SEMMSL
89 #define SEMMSL SEMMNS /* max # of semaphores per id */
90 #endif
91 #ifndef SEMOPM
92 #define SEMOPM 100 /* max # of operations per semop call */
93 #endif
94
95 #define SEMVMX 32767 /* semaphore maximum value */
96 #define SEMAEM 16384 /* adjust on exit max value */
97
98 /*
99 * Due to the way semaphore memory is allocated, we have to ensure that
100 * SEMUSZ is properly aligned.
101 */
102
103 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
104
105 /* actual size of an undo structure */
106 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
107
108 /*
109 * Macro to find a particular sem_undo vector
110 */
111 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
112
113 /*
114 * semaphore info struct
115 */
116 struct seminfo seminfo = {
117 SEMMAP, /* # of entries in semaphore map */
118 SEMMNI, /* # of semaphore identifiers */
119 SEMMNS, /* # of semaphores in system */
120 SEMMNU, /* # of undo structures in system */
121 SEMMSL, /* max # of semaphores per id */
122 SEMOPM, /* max # of operations per semop call */
123 SEMUME, /* max # of undo entries per process */
124 SEMUSZ, /* size in bytes of undo structure */
125 SEMVMX, /* semaphore maximum value */
126 SEMAEM /* adjust on exit max value */
127 };
128
129 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap);
130 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni);
131 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns);
132 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu);
133 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl);
134 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm);
135 TUNABLE_INT("kern.ipc.semume", &seminfo.semume);
136 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz);
137 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx);
138 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem);
139
140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0,
141 "Number of entries in semaphore map");
142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0,
143 "Number of semaphore identifiers");
144 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0,
145 "Total number of semaphores");
146 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0,
147 "Total number of undo structures");
148 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0,
149 "Max number of semaphores per id");
150 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0,
151 "Max number of operations per semop call");
152 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0,
153 "Max number of undo entries per process");
154 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0,
155 "Size in bytes of undo structure");
156 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0,
157 "Semaphore maximum value");
158 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0,
159 "Adjust on exit max value");
160
161 #if 0
162 RO seminfo.semmap /* SEMMAP unused */
163 RO seminfo.semmni
164 RO seminfo.semmns
165 RO seminfo.semmnu /* undo entries per system */
166 RW seminfo.semmsl
167 RO seminfo.semopm /* SEMOPM unused */
168 RO seminfo.semume
169 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */
170 RO seminfo.semvmx /* SEMVMX unused - user param */
171 RO seminfo.semaem /* SEMAEM unused - user param */
172 #endif
173
174 static void
175 seminit(void *dummy)
176 {
177 int i;
178
179 sem = kmalloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
180 sema = kmalloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK);
181 semu = kmalloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
182
183 for (i = 0; i < seminfo.semmni; i++) {
184 sema[i].sem_base = 0;
185 sema[i].sem_perm.mode = 0;
186 }
187 for (i = 0; i < seminfo.semmnu; i++) {
188 struct sem_undo *suptr = SEMU(i);
189 suptr->un_proc = NULL;
190 }
191 semu_list = NULL;
192 }
193 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
194
195 /*
196 * Entry point for all SEM calls
197 *
198 * semsys_args(int which, a2, a3, ...) (VARARGS)
199 *
200 * MPALMOSTSAFE
201 */
202 int
203 sys_semsys(struct semsys_args *uap)
204 {
205 struct thread *td = curthread;
206 unsigned int which = (unsigned int)uap->which;
207 int error;
208
209 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
210 return (ENOSYS);
211
212 if (which >= NELEM(semcalls))
213 return (EINVAL);
214 bcopy(&uap->a2, &uap->which,
215 sizeof(struct semsys_args) - offsetof(struct semsys_args, a2));
216 get_mplock();
217 error = (*semcalls[which])(uap);
218 rel_mplock();
219 return (error);
220 }
221
222 /*
223 * Allocate a new sem_undo structure for a process
224 * (returns ptr to structure or NULL if no more room)
225 */
226
227 static struct sem_undo *
228 semu_alloc(struct proc *p)
229 {
230 int i;
231 struct sem_undo *suptr;
232 struct sem_undo **supptr;
233 int attempt;
234
235 /*
236 * Try twice to allocate something.
237 * (we'll purge any empty structures after the first pass so
238 * two passes are always enough)
239 */
240
241 for (attempt = 0; attempt < 2; attempt++) {
242 /*
243 * Look for a free structure.
244 * Fill it in and return it if we find one.
245 */
246
247 for (i = 0; i < seminfo.semmnu; i++) {
248 suptr = SEMU(i);
249 if (suptr->un_proc == NULL) {
250 suptr->un_next = semu_list;
251 semu_list = suptr;
252 suptr->un_cnt = 0;
253 suptr->un_proc = p;
254 return(suptr);
255 }
256 }
257
258 /*
259 * We didn't find a free one, if this is the first attempt
260 * then try to free some structures.
261 */
262
263 if (attempt == 0) {
264 /* All the structures are in use - try to free some */
265 int did_something = 0;
266
267 supptr = &semu_list;
268 while ((suptr = *supptr) != NULL) {
269 if (suptr->un_cnt == 0) {
270 suptr->un_proc = NULL;
271 *supptr = suptr->un_next;
272 did_something = 1;
273 } else
274 supptr = &(suptr->un_next);
275 }
276
277 /* If we didn't free anything then just give-up */
278 if (!did_something)
279 return(NULL);
280 } else {
281 /*
282 * The second pass failed even though we freed
283 * something after the first pass!
284 * This is IMPOSSIBLE!
285 */
286 panic("semu_alloc - second attempt failed");
287 }
288 }
289 return (NULL);
290 }
291
292 /*
293 * Adjust a particular entry for a particular proc
294 */
295
296 static int
297 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
298 int adjval)
299 {
300 struct sem_undo *suptr;
301 struct undo *sunptr;
302 int i;
303
304 /* Look for and remember the sem_undo if the caller doesn't provide
305 it */
306
307 suptr = *supptr;
308 if (suptr == NULL) {
309 for (suptr = semu_list; suptr != NULL;
310 suptr = suptr->un_next) {
311 if (suptr->un_proc == p) {
312 *supptr = suptr;
313 break;
314 }
315 }
316 if (suptr == NULL) {
317 if (adjval == 0)
318 return(0);
319 suptr = semu_alloc(p);
320 if (suptr == NULL)
321 return(ENOSPC);
322 *supptr = suptr;
323 }
324 }
325
326 /*
327 * Look for the requested entry and adjust it (delete if adjval becomes
328 * 0).
329 */
330 sunptr = &suptr->un_ent[0];
331 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
332 if (sunptr->un_id != semid || sunptr->un_num != semnum)
333 continue;
334 if (adjval == 0)
335 sunptr->un_adjval = 0;
336 else
337 sunptr->un_adjval += adjval;
338 if (sunptr->un_adjval == 0) {
339 suptr->un_cnt--;
340 if (i < suptr->un_cnt)
341 suptr->un_ent[i] =
342 suptr->un_ent[suptr->un_cnt];
343 }
344 return(0);
345 }
346
347 /* Didn't find the right entry - create it */
348 if (adjval == 0)
349 return(0);
350 if (suptr->un_cnt != seminfo.semume) {
351 sunptr = &suptr->un_ent[suptr->un_cnt];
352 suptr->un_cnt++;
353 sunptr->un_adjval = adjval;
354 sunptr->un_id = semid; sunptr->un_num = semnum;
355 } else
356 return(EINVAL);
357 return(0);
358 }
359
360 static void
361 semundo_clear(int semid, int semnum)
362 {
363 struct sem_undo *suptr;
364
365 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
366 struct undo *sunptr = &suptr->un_ent[0];
367 int i = 0;
368
369 while (i < suptr->un_cnt) {
370 if (sunptr->un_id == semid) {
371 if (semnum == -1 || sunptr->un_num == semnum) {
372 suptr->un_cnt--;
373 if (i < suptr->un_cnt) {
374 suptr->un_ent[i] =
375 suptr->un_ent[suptr->un_cnt];
376 continue;
377 }
378 }
379 if (semnum != -1)
380 break;
381 }
382 i++, sunptr++;
383 }
384 }
385 }
386
387 /*
388 * Note that the user-mode half of this passes a union, not a pointer
389 *
390 * MPALMOSTSAFE
391 */
392 int
393 sys___semctl(struct __semctl_args *uap)
394 {
395 struct thread *td = curthread;
396 int semid = uap->semid;
397 int semnum = uap->semnum;
398 int cmd = uap->cmd;
399 union semun *arg = uap->arg;
400 union semun real_arg;
401 struct ucred *cred = td->td_ucred;
402 int i, rval, eval;
403 struct semid_ds sbuf;
404 struct semid_ds *semaptr;
405 struct semid_ds *semakptr;
406
407 #ifdef SEM_DEBUG
408 kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
409 #endif
410
411 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
412 return (ENOSYS);
413
414 get_mplock();
415 switch (cmd) {
416 case SEM_STAT:
417 /*
418 * For this command we assume semid is an array index
419 * rather than an IPC id.
420 */
421 if (semid < 0 || semid >= seminfo.semmni) {
422 eval = EINVAL;
423 break;
424 }
425 semakptr = &sema[semid];
426 if ((semakptr->sem_perm.mode & SEM_ALLOC) == 0) {
427 eval = EINVAL;
428 break;
429 }
430 if ((eval = ipcperm(td->td_proc, &semakptr->sem_perm, IPC_R)))
431 break;
432
433 bcopy(&semakptr, arg->buf, sizeof(struct semid_ds));
434 rval = IXSEQ_TO_IPCID(semid, semakptr->sem_perm);
435 break;
436 }
437
438 semid = IPCID_TO_IX(semid);
439 if (semid < 0 || semid >= seminfo.semmni) {
440 rel_mplock();
441 return(EINVAL);
442 }
443
444 semaptr = &sema[semid];
445 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
446 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
447 rel_mplock();
448 return(EINVAL);
449 }
450
451 eval = 0;
452 rval = 0;
453
454 switch (cmd) {
455 case IPC_RMID:
456 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_M)) != 0)
457 break;
458 semaptr->sem_perm.cuid = cred->cr_uid;
459 semaptr->sem_perm.uid = cred->cr_uid;
460 semtot -= semaptr->sem_nsems;
461 for (i = semaptr->sem_base - sem; i < semtot; i++)
462 sem[i] = sem[i + semaptr->sem_nsems];
463 for (i = 0; i < seminfo.semmni; i++) {
464 if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
465 sema[i].sem_base > semaptr->sem_base)
466 sema[i].sem_base -= semaptr->sem_nsems;
467 }
468 semaptr->sem_perm.mode = 0;
469 semundo_clear(semid, -1);
470 wakeup((caddr_t)semaptr);
471 break;
472
473 case IPC_SET:
474 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_M);
475 if (eval)
476 break;
477 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
478 break;
479 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
480 sizeof(sbuf))) != 0) {
481 break;
482 }
483 semaptr->sem_perm.uid = sbuf.sem_perm.uid;
484 semaptr->sem_perm.gid = sbuf.sem_perm.gid;
485 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
486 (sbuf.sem_perm.mode & 0777);
487 semaptr->sem_ctime = time_second;
488 break;
489
490 case IPC_STAT:
491 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R)))
492 break;
493 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
494 break;
495 eval = copyout(semaptr, real_arg.buf, sizeof(struct semid_ds));
496 break;
497
498 case GETNCNT:
499 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
500 if (eval)
501 break;
502 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
503 eval = EINVAL;
504 break;
505 }
506 rval = semaptr->sem_base[semnum].semncnt;
507 break;
508
509 case GETPID:
510 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
511 if (eval)
512 break;
513 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
514 eval = EINVAL;
515 break;
516 }
517 rval = semaptr->sem_base[semnum].sempid;
518 break;
519
520 case GETVAL:
521 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
522 if (eval)
523 break;
524 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
525 eval = EINVAL;
526 break;
527 }
528 rval = semaptr->sem_base[semnum].semval;
529 break;
530
531 case GETALL:
532 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
533 if (eval)
534 break;
535 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
536 break;
537 for (i = 0; i < semaptr->sem_nsems; i++) {
538 eval = copyout(&semaptr->sem_base[i].semval,
539 &real_arg.array[i],
540 sizeof(real_arg.array[0]));
541 if (eval)
542 break;
543 }
544 break;
545
546 case GETZCNT:
547 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
548 if (eval)
549 break;
550 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
551 eval = EINVAL;
552 break;
553 }
554 rval = semaptr->sem_base[semnum].semzcnt;
555 break;
556
557 case SETVAL:
558 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W);
559 if (eval)
560 break;
561 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
562 eval = EINVAL;
563 break;
564 }
565 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
566 break;
567 semaptr->sem_base[semnum].semval = real_arg.val;
568 semundo_clear(semid, semnum);
569 wakeup((caddr_t)semaptr);
570 break;
571
572 case SETALL:
573 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W);
574 if (eval)
575 break;
576 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
577 break;
578 for (i = 0; i < semaptr->sem_nsems; i++) {
579 eval = copyin(&real_arg.array[i],
580 (caddr_t)&semaptr->sem_base[i].semval,
581 sizeof(real_arg.array[0]));
582 if (eval != 0)
583 break;
584 }
585 semundo_clear(semid, -1);
586 wakeup((caddr_t)semaptr);
587 break;
588
589 default:
590 eval = EINVAL;
591 break;
592 }
593 rel_mplock();
594
595 if (eval == 0)
596 uap->sysmsg_result = rval;
597 return(eval);
598 }
599
600 /*
601 * MPALMOSTSAFE
602 */
603 int
604 sys_semget(struct semget_args *uap)
605 {
606 struct thread *td = curthread;
607 int semid, eval;
608 int key = uap->key;
609 int nsems = uap->nsems;
610 int semflg = uap->semflg;
611 struct ucred *cred = td->td_ucred;
612
613 #ifdef SEM_DEBUG
614 kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
615 #endif
616
617 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
618 return (ENOSYS);
619
620 get_mplock();
621 eval = 0;
622
623 if (key != IPC_PRIVATE) {
624 for (semid = 0; semid < seminfo.semmni; semid++) {
625 if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
626 sema[semid].sem_perm.key == key)
627 break;
628 }
629 if (semid < seminfo.semmni) {
630 #ifdef SEM_DEBUG
631 kprintf("found public key\n");
632 #endif
633 if ((eval = ipcperm(td->td_proc,
634 &sema[semid].sem_perm,
635 semflg & 0700))) {
636 goto done;
637 }
638 if (nsems > 0 && sema[semid].sem_nsems < nsems) {
639 #ifdef SEM_DEBUG
640 kprintf("too small\n");
641 #endif
642 eval = EINVAL;
643 goto done;
644 }
645 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
646 #ifdef SEM_DEBUG
647 kprintf("not exclusive\n");
648 #endif
649 eval = EEXIST;
650 goto done;
651 }
652 goto done;
653 }
654 }
655
656 #ifdef SEM_DEBUG
657 kprintf("need to allocate the semid_ds\n");
658 #endif
659 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
660 if (nsems <= 0 || nsems > seminfo.semmsl) {
661 #ifdef SEM_DEBUG
662 kprintf("nsems out of range (0<%d<=%d)\n", nsems,
663 seminfo.semmsl);
664 #endif
665 eval = EINVAL;
666 goto done;
667 }
668 if (nsems > seminfo.semmns - semtot) {
669 #ifdef SEM_DEBUG
670 kprintf("not enough semaphores left (need %d, got %d)\n",
671 nsems, seminfo.semmns - semtot);
672 #endif
673 eval = ENOSPC;
674 goto done;
675 }
676 for (semid = 0; semid < seminfo.semmni; semid++) {
677 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
678 break;
679 }
680 if (semid == seminfo.semmni) {
681 #ifdef SEM_DEBUG
682 kprintf("no more semid_ds's available\n");
683 #endif
684 eval = ENOSPC;
685 goto done;
686 }
687 #ifdef SEM_DEBUG
688 kprintf("semid %d is available\n", semid);
689 #endif
690 sema[semid].sem_perm.key = key;
691 sema[semid].sem_perm.cuid = cred->cr_uid;
692 sema[semid].sem_perm.uid = cred->cr_uid;
693 sema[semid].sem_perm.cgid = cred->cr_gid;
694 sema[semid].sem_perm.gid = cred->cr_gid;
695 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
696 sema[semid].sem_perm.seq =
697 (sema[semid].sem_perm.seq + 1) & 0x7fff;
698 sema[semid].sem_nsems = nsems;
699 sema[semid].sem_otime = 0;
700 sema[semid].sem_ctime = time_second;
701 sema[semid].sem_base = &sem[semtot];
702 semtot += nsems;
703 bzero(sema[semid].sem_base,
704 sizeof(sema[semid].sem_base[0])*nsems);
705 #ifdef SEM_DEBUG
706 kprintf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
707 &sem[semtot]);
708 #endif
709 } else {
710 #ifdef SEM_DEBUG
711 kprintf("didn't find it and wasn't asked to create it\n");
712 #endif
713 eval = ENOENT;
714 }
715
716 done:
717 if (eval == 0) {
718 uap->sysmsg_result = IXSEQ_TO_IPCID(semid,
719 sema[semid].sem_perm);
720 }
721 rel_mplock();
722 return(eval);
723 }
724
725 /*
726 * MPALMOSTSAFE
727 */
728 int
729 sys_semop(struct semop_args *uap)
730 {
731 struct thread *td = curthread;
732 int semid = uap->semid;
733 u_int nsops = uap->nsops;
734 struct sembuf sops[MAX_SOPS];
735 struct semid_ds *semaptr;
736 struct sembuf *sopptr;
737 struct sem *semptr;
738 struct sem_undo *suptr = NULL;
739 int i, j, eval;
740 int do_wakeup, do_undos;
741
742 #ifdef SEM_DEBUG
743 kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
744 #endif
745
746 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
747 return (ENOSYS);
748
749 get_mplock();
750 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
751
752 if (semid < 0 || semid >= seminfo.semmni) {
753 eval = EINVAL;
754 goto done;
755 }
756
757 semaptr = &sema[semid];
758 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) {
759 eval = EINVAL;
760 goto done;
761 }
762 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
763 eval = EINVAL;
764 goto done;
765 }
766
767 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W))) {
768 #ifdef SEM_DEBUG
769 kprintf("eval = %d from ipaccess\n", eval);
770 #endif
771 goto done;
772 }
773
774 if (nsops > MAX_SOPS) {
775 #ifdef SEM_DEBUG
776 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops);
777 #endif
778 eval = E2BIG;
779 goto done;
780 }
781
782 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
783 #ifdef SEM_DEBUG
784 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval,
785 uap->sops, &sops, nsops * sizeof(sops[0]));
786 #endif
787 goto done;
788 }
789
790 /*
791 * Loop trying to satisfy the vector of requests.
792 * If we reach a point where we must wait, any requests already
793 * performed are rolled back and we go to sleep until some other
794 * process wakes us up. At this point, we start all over again.
795 *
796 * This ensures that from the perspective of other tasks, a set
797 * of requests is atomic (never partially satisfied).
798 */
799 do_undos = 0;
800
801 for (;;) {
802 do_wakeup = 0;
803
804 for (i = 0; i < nsops; i++) {
805 sopptr = &sops[i];
806
807 if (sopptr->sem_num >= semaptr->sem_nsems) {
808 eval = EFBIG;
809 goto done;
810 }
811
812 semptr = &semaptr->sem_base[sopptr->sem_num];
813
814 #ifdef SEM_DEBUG
815 kprintf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
816 semaptr, semaptr->sem_base, semptr,
817 sopptr->sem_num, semptr->semval, sopptr->sem_op,
818 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
819 #endif
820
821 if (sopptr->sem_op < 0) {
822 if (semptr->semval + sopptr->sem_op < 0) {
823 #ifdef SEM_DEBUG
824 kprintf("semop: can't do it now\n");
825 #endif
826 break;
827 } else {
828 semptr->semval += sopptr->sem_op;
829 if (semptr->semval == 0 &&
830 semptr->semzcnt > 0)
831 do_wakeup = 1;
832 }
833 if (sopptr->sem_flg & SEM_UNDO)
834 do_undos = 1;
835 } else if (sopptr->sem_op == 0) {
836 if (semptr->semval > 0) {
837 #ifdef SEM_DEBUG
838 kprintf("semop: not zero now\n");
839 #endif
840 break;
841 }
842 } else {
843 if (semptr->semncnt > 0)
844 do_wakeup = 1;
845 semptr->semval += sopptr->sem_op;
846 if (sopptr->sem_flg & SEM_UNDO)
847 do_undos = 1;
848 }
849 }
850
851 /*
852 * Did we get through the entire vector?
853 */
854 if (i >= nsops)
855 goto donex;
856
857 /*
858 * No ... rollback anything that we've already done
859 */
860 #ifdef SEM_DEBUG
861 kprintf("semop: rollback 0 through %d\n", i-1);
862 #endif
863 for (j = 0; j < i; j++)
864 semaptr->sem_base[sops[j].sem_num].semval -=
865 sops[j].sem_op;
866
867 /*
868 * If the request that we couldn't satisfy has the
869 * NOWAIT flag set then return with EAGAIN.
870 */
871 if (sopptr->sem_flg & IPC_NOWAIT) {
872 eval = EAGAIN;
873 goto done;
874 }
875
876 if (sopptr->sem_op == 0)
877 semptr->semzcnt++;
878 else
879 semptr->semncnt++;
880
881 #ifdef SEM_DEBUG
882 kprintf("semop: good night!\n");
883 #endif
884 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0);
885 #ifdef SEM_DEBUG
886 kprintf("semop: good morning (eval=%d)!\n", eval);
887 #endif
888
889 suptr = NULL; /* sem_undo may have been reallocated */
890
891 /* return code is checked below, after sem[nz]cnt-- */
892
893 /*
894 * Make sure that the semaphore still exists
895 */
896 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
897 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
898 eval = EIDRM;
899 goto done;
900 }
901
902 /*
903 * The semaphore is still alive. Readjust the count of
904 * waiting processes.
905 */
906 if (sopptr->sem_op == 0)
907 semptr->semzcnt--;
908 else
909 semptr->semncnt--;
910
911 /*
912 * Is it really morning, or was our sleep interrupted?
913 * (Delayed check of tsleep() return code because we
914 * need to decrement sem[nz]cnt either way.)
915 */
916 if (eval) {
917 eval = EINTR;
918 goto done;
919 }
920 #ifdef SEM_DEBUG
921 kprintf("semop: good morning!\n");
922 #endif
923 }
924
925 donex:
926 /*
927 * Process any SEM_UNDO requests.
928 */
929 if (do_undos) {
930 for (i = 0; i < nsops; i++) {
931 /*
932 * We only need to deal with SEM_UNDO's for non-zero
933 * op's.
934 */
935 int adjval;
936
937 if ((sops[i].sem_flg & SEM_UNDO) == 0)
938 continue;
939 adjval = sops[i].sem_op;
940 if (adjval == 0)
941 continue;
942 eval = semundo_adjust(td->td_proc, &suptr, semid,
943 sops[i].sem_num, -adjval);
944 if (eval == 0)
945 continue;
946
947 /*
948 * Oh-Oh! We ran out of either sem_undo's or undo's.
949 * Rollback the adjustments to this point and then
950 * rollback the semaphore ups and down so we can return
951 * with an error with all structures restored. We
952 * rollback the undo's in the exact reverse order that
953 * we applied them. This guarantees that we won't run
954 * out of space as we roll things back out.
955 */
956 for (j = i - 1; j >= 0; j--) {
957 if ((sops[j].sem_flg & SEM_UNDO) == 0)
958 continue;
959 adjval = sops[j].sem_op;
960 if (adjval == 0)
961 continue;
962 if (semundo_adjust(td->td_proc, &suptr, semid,
963 sops[j].sem_num, adjval) != 0)
964 panic("semop - can't undo undos");
965 }
966
967 for (j = 0; j < nsops; j++)
968 semaptr->sem_base[sops[j].sem_num].semval -=
969 sops[j].sem_op;
970
971 #ifdef SEM_DEBUG
972 kprintf("eval = %d from semundo_adjust\n", eval);
973 #endif
974 goto done;
975 } /* loop through the sops */
976 } /* if (do_undos) */
977
978 /* We're definitely done - set the sempid's */
979 for (i = 0; i < nsops; i++) {
980 sopptr = &sops[i];
981 semptr = &semaptr->sem_base[sopptr->sem_num];
982 semptr->sempid = td->td_proc->p_pid;
983 }
984
985 /* Do a wakeup if any semaphore was up'd. */
986 if (do_wakeup) {
987 #ifdef SEM_DEBUG
988 kprintf("semop: doing wakeup\n");
989 #endif
990 wakeup((caddr_t)semaptr);
991 #ifdef SEM_DEBUG
992 kprintf("semop: back from wakeup\n");
993 #endif
994 }
995 #ifdef SEM_DEBUG
996 kprintf("semop: done\n");
997 #endif
998 uap->sysmsg_result = 0;
999 eval = 0;
1000 done:
1001 rel_mplock();
1002 return(eval);
1003 }
1004
1005 /*
1006 * Go through the undo structures for this process and apply the adjustments to
1007 * semaphores.
1008 */
1009 void
1010 semexit(struct proc *p)
1011 {
1012 struct sem_undo *suptr;
1013 struct sem_undo **supptr;
1014 int did_something;
1015
1016 did_something = 0;
1017
1018 /*
1019 * Go through the chain of undo vectors looking for one
1020 * associated with this process.
1021 */
1022
1023 for (supptr = &semu_list; (suptr = *supptr) != NULL;
1024 supptr = &suptr->un_next) {
1025 if (suptr->un_proc == p)
1026 break;
1027 }
1028
1029 if (suptr == NULL)
1030 return;
1031
1032 #ifdef SEM_DEBUG
1033 kprintf("proc @%08x has undo structure with %d entries\n", p,
1034 suptr->un_cnt);
1035 #endif
1036
1037 /*
1038 * If there are any active undo elements then process them.
1039 */
1040 if (suptr->un_cnt > 0) {
1041 int ix;
1042
1043 for (ix = 0; ix < suptr->un_cnt; ix++) {
1044 int semid = suptr->un_ent[ix].un_id;
1045 int semnum = suptr->un_ent[ix].un_num;
1046 int adjval = suptr->un_ent[ix].un_adjval;
1047 struct semid_ds *semaptr;
1048
1049 semaptr = &sema[semid];
1050 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
1051 panic("semexit - semid not allocated");
1052 if (semnum >= semaptr->sem_nsems)
1053 panic("semexit - semnum out of range");
1054
1055 #ifdef SEM_DEBUG
1056 kprintf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n",
1057 suptr->un_proc, suptr->un_ent[ix].un_id,
1058 suptr->un_ent[ix].un_num,
1059 suptr->un_ent[ix].un_adjval,
1060 semaptr->sem_base[semnum].semval);
1061 #endif
1062
1063 if (adjval < 0) {
1064 if (semaptr->sem_base[semnum].semval < -adjval)
1065 semaptr->sem_base[semnum].semval = 0;
1066 else
1067 semaptr->sem_base[semnum].semval +=
1068 adjval;
1069 } else
1070 semaptr->sem_base[semnum].semval += adjval;
1071
1072 wakeup((caddr_t)semaptr);
1073 #ifdef SEM_DEBUG
1074 kprintf("semexit: back from wakeup\n");
1075 #endif
1076 }
1077 }
1078
1079 /*
1080 * Deallocate the undo vector.
1081 */
1082 #ifdef SEM_DEBUG
1083 kprintf("removing vector\n");
1084 #endif
1085 suptr->un_proc = NULL;
1086 *supptr = suptr->un_next;
1087 }
DragonFly BSD