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We only need to determine the softlink_dir when no filesystem is
[dragonfly.git] / sys / kern / sysv_sem.c
blobf207bfcff712e4a2f926d971fde1a879febbdcd6
1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.69 2004/03/17 09:37:13 cperciva Exp $ */
2 /* $DragonFly: src/sys/kern/sysv_sem.c,v 1.19 2008/01/06 16:55:51 swildner Exp $ */
3
4 /*
5 * Implementation of SVID semaphores
6 *
7 * Author: Daniel Boulet
8 *
9 * This software is provided ``AS IS'' without any warranties of any kind.
10 */
11
12 #include "opt_sysvipc.h"
13
14 #include <sys/param.h>
15 #include <sys/systm.h>
16 #include <sys/sysproto.h>
17 #include <sys/kernel.h>
18 #include <sys/proc.h>
19 #include <sys/sem.h>
20 #include <sys/sysent.h>
21 #include <sys/sysctl.h>
22 #include <sys/malloc.h>
23 #include <sys/jail.h>
24
25 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
26
27 static void seminit (void *);
28
29 static struct sem_undo *semu_alloc (struct proc *p);
30 static int semundo_adjust (struct proc *p, struct sem_undo **supptr,
31 int semid, int semnum, int adjval);
32 static void semundo_clear (int semid, int semnum);
33
34 /* XXX casting to (sy_call_t *) is bogus, as usual. */
35 static sy_call_t *semcalls[] = {
36 (sy_call_t *)sys___semctl, (sy_call_t *)sys_semget,
37 (sy_call_t *)sys_semop
38 };
39
40 static int semtot = 0;
41 static struct semid_ds *sema; /* semaphore id pool */
42 static struct sem *sem; /* semaphore pool */
43 static struct sem_undo *semu_list; /* list of active undo structures */
44 static int *semu; /* undo structure pool */
45
46 struct sem {
47 u_short semval; /* semaphore value */
48 pid_t sempid; /* pid of last operation */
49 u_short semncnt; /* # awaiting semval > cval */
50 u_short semzcnt; /* # awaiting semval = 0 */
51 };
52
53 /*
54 * Undo structure (one per process)
55 */
56 struct sem_undo {
57 struct sem_undo *un_next; /* ptr to next active undo structure */
58 struct proc *un_proc; /* owner of this structure */
59 short un_cnt; /* # of active entries */
60 struct undo {
61 short un_adjval; /* adjust on exit values */
62 short un_num; /* semaphore # */
63 int un_id; /* semid */
64 } un_ent[1]; /* undo entries */
65 };
66
67 /*
68 * Configuration parameters
69 */
70 #ifndef SEMMNI
71 #define SEMMNI 10 /* # of semaphore identifiers */
72 #endif
73 #ifndef SEMMNS
74 #define SEMMNS 60 /* # of semaphores in system */
75 #endif
76 #ifndef SEMUME
77 #define SEMUME 10 /* max # of undo entries per process */
78 #endif
79 #ifndef SEMMNU
80 #define SEMMNU 30 /* # of undo structures in system */
81 #endif
82
83 /* shouldn't need tuning */
84 #ifndef SEMMAP
85 #define SEMMAP 30 /* # of entries in semaphore map */
86 #endif
87 #ifndef SEMMSL
88 #define SEMMSL SEMMNS /* max # of semaphores per id */
89 #endif
90 #ifndef SEMOPM
91 #define SEMOPM 100 /* max # of operations per semop call */
92 #endif
93
94 #define SEMVMX 32767 /* semaphore maximum value */
95 #define SEMAEM 16384 /* adjust on exit max value */
96
97 /*
98 * Due to the way semaphore memory is allocated, we have to ensure that
99 * SEMUSZ is properly aligned.
100 */
101
102 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
103
104 /* actual size of an undo structure */
105 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
106
107 /*
108 * Macro to find a particular sem_undo vector
109 */
110 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
111
112 /*
113 * semaphore info struct
114 */
115 struct seminfo seminfo = {
116 SEMMAP, /* # of entries in semaphore map */
117 SEMMNI, /* # of semaphore identifiers */
118 SEMMNS, /* # of semaphores in system */
119 SEMMNU, /* # of undo structures in system */
120 SEMMSL, /* max # of semaphores per id */
121 SEMOPM, /* max # of operations per semop call */
122 SEMUME, /* max # of undo entries per process */
123 SEMUSZ, /* size in bytes of undo structure */
124 SEMVMX, /* semaphore maximum value */
125 SEMAEM /* adjust on exit max value */
126 };
127
128 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap);
129 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni);
130 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns);
131 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu);
132 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl);
133 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm);
134 TUNABLE_INT("kern.ipc.semume", &seminfo.semume);
135 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz);
136 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx);
137 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem);
138
139 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "");
140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, "");
141 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, "");
142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, "");
143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "");
144 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, "");
145 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, "");
146 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, "");
147 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "");
148 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "");
149
150 #if 0
151 RO seminfo.semmap /* SEMMAP unused */
152 RO seminfo.semmni
153 RO seminfo.semmns
154 RO seminfo.semmnu /* undo entries per system */
155 RW seminfo.semmsl
156 RO seminfo.semopm /* SEMOPM unused */
157 RO seminfo.semume
158 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */
159 RO seminfo.semvmx /* SEMVMX unused - user param */
160 RO seminfo.semaem /* SEMAEM unused - user param */
161 #endif
162
163 static void
164 seminit(void *dummy)
165 {
166 int i;
167
168 sem = kmalloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
169 sema = kmalloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK);
170 semu = kmalloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
171
172 for (i = 0; i < seminfo.semmni; i++) {
173 sema[i].sem_base = 0;
174 sema[i].sem_perm.mode = 0;
175 }
176 for (i = 0; i < seminfo.semmnu; i++) {
177 struct sem_undo *suptr = SEMU(i);
178 suptr->un_proc = NULL;
179 }
180 semu_list = NULL;
181 }
182 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
183
184 /*
185 * Entry point for all SEM calls
186 *
187 * semsys_args(int which, a2, a3, ...) (VARARGS)
188 */
189 int
190 sys_semsys(struct semsys_args *uap)
191 {
192 struct proc *p = curproc;
193 unsigned int which = (unsigned int)uap->which;
194
195 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
196 return (ENOSYS);
197
198 if (which >= sizeof(semcalls)/sizeof(semcalls[0]))
199 return (EINVAL);
200 bcopy(&uap->a2, &uap->which,
201 sizeof(struct semsys_args) - offsetof(struct semsys_args, a2));
202 return ((*semcalls[which])(uap));
203 }
204
205 /*
206 * Allocate a new sem_undo structure for a process
207 * (returns ptr to structure or NULL if no more room)
208 */
209
210 static struct sem_undo *
211 semu_alloc(struct proc *p)
212 {
213 int i;
214 struct sem_undo *suptr;
215 struct sem_undo **supptr;
216 int attempt;
217
218 /*
219 * Try twice to allocate something.
220 * (we'll purge any empty structures after the first pass so
221 * two passes are always enough)
222 */
223
224 for (attempt = 0; attempt < 2; attempt++) {
225 /*
226 * Look for a free structure.
227 * Fill it in and return it if we find one.
228 */
229
230 for (i = 0; i < seminfo.semmnu; i++) {
231 suptr = SEMU(i);
232 if (suptr->un_proc == NULL) {
233 suptr->un_next = semu_list;
234 semu_list = suptr;
235 suptr->un_cnt = 0;
236 suptr->un_proc = p;
237 return(suptr);
238 }
239 }
240
241 /*
242 * We didn't find a free one, if this is the first attempt
243 * then try to free some structures.
244 */
245
246 if (attempt == 0) {
247 /* All the structures are in use - try to free some */
248 int did_something = 0;
249
250 supptr = &semu_list;
251 while ((suptr = *supptr) != NULL) {
252 if (suptr->un_cnt == 0) {
253 suptr->un_proc = NULL;
254 *supptr = suptr->un_next;
255 did_something = 1;
256 } else
257 supptr = &(suptr->un_next);
258 }
259
260 /* If we didn't free anything then just give-up */
261 if (!did_something)
262 return(NULL);
263 } else {
264 /*
265 * The second pass failed even though we freed
266 * something after the first pass!
267 * This is IMPOSSIBLE!
268 */
269 panic("semu_alloc - second attempt failed");
270 }
271 }
272 return (NULL);
273 }
274
275 /*
276 * Adjust a particular entry for a particular proc
277 */
278
279 static int
280 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
281 int adjval)
282 {
283 struct sem_undo *suptr;
284 struct undo *sunptr;
285 int i;
286
287 /* Look for and remember the sem_undo if the caller doesn't provide
288 it */
289
290 suptr = *supptr;
291 if (suptr == NULL) {
292 for (suptr = semu_list; suptr != NULL;
293 suptr = suptr->un_next) {
294 if (suptr->un_proc == p) {
295 *supptr = suptr;
296 break;
297 }
298 }
299 if (suptr == NULL) {
300 if (adjval == 0)
301 return(0);
302 suptr = semu_alloc(p);
303 if (suptr == NULL)
304 return(ENOSPC);
305 *supptr = suptr;
306 }
307 }
308
309 /*
310 * Look for the requested entry and adjust it (delete if adjval becomes
311 * 0).
312 */
313 sunptr = &suptr->un_ent[0];
314 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
315 if (sunptr->un_id != semid || sunptr->un_num != semnum)
316 continue;
317 if (adjval == 0)
318 sunptr->un_adjval = 0;
319 else
320 sunptr->un_adjval += adjval;
321 if (sunptr->un_adjval == 0) {
322 suptr->un_cnt--;
323 if (i < suptr->un_cnt)
324 suptr->un_ent[i] =
325 suptr->un_ent[suptr->un_cnt];
326 }
327 return(0);
328 }
329
330 /* Didn't find the right entry - create it */
331 if (adjval == 0)
332 return(0);
333 if (suptr->un_cnt != seminfo.semume) {
334 sunptr = &suptr->un_ent[suptr->un_cnt];
335 suptr->un_cnt++;
336 sunptr->un_adjval = adjval;
337 sunptr->un_id = semid; sunptr->un_num = semnum;
338 } else
339 return(EINVAL);
340 return(0);
341 }
342
343 static void
344 semundo_clear(int semid, int semnum)
345 {
346 struct sem_undo *suptr;
347
348 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
349 struct undo *sunptr = &suptr->un_ent[0];
350 int i = 0;
351
352 while (i < suptr->un_cnt) {
353 if (sunptr->un_id == semid) {
354 if (semnum == -1 || sunptr->un_num == semnum) {
355 suptr->un_cnt--;
356 if (i < suptr->un_cnt) {
357 suptr->un_ent[i] =
358 suptr->un_ent[suptr->un_cnt];
359 continue;
360 }
361 }
362 if (semnum != -1)
363 break;
364 }
365 i++, sunptr++;
366 }
367 }
368 }
369
370 /*
371 * Note that the user-mode half of this passes a union, not a pointer
372 */
373
374 int
375 sys___semctl(struct __semctl_args *uap)
376 {
377 struct proc *p = curproc;
378 int semid = uap->semid;
379 int semnum = uap->semnum;
380 int cmd = uap->cmd;
381 union semun *arg = uap->arg;
382 union semun real_arg;
383 struct ucred *cred = p->p_ucred;
384 int i, rval, eval;
385 struct semid_ds sbuf;
386 struct semid_ds *semaptr;
387
388 #ifdef SEM_DEBUG
389 kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
390 #endif
391
392 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
393 return (ENOSYS);
394
395 semid = IPCID_TO_IX(semid);
396 if (semid < 0 || semid >= seminfo.semmni)
397 return(EINVAL);
398
399 semaptr = &sema[semid];
400 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
401 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
402 return(EINVAL);
403
404 eval = 0;
405 rval = 0;
406
407 switch (cmd) {
408 case IPC_RMID:
409 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M)))
410 return(eval);
411 semaptr->sem_perm.cuid = cred->cr_uid;
412 semaptr->sem_perm.uid = cred->cr_uid;
413 semtot -= semaptr->sem_nsems;
414 for (i = semaptr->sem_base - sem; i < semtot; i++)
415 sem[i] = sem[i + semaptr->sem_nsems];
416 for (i = 0; i < seminfo.semmni; i++) {
417 if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
418 sema[i].sem_base > semaptr->sem_base)
419 sema[i].sem_base -= semaptr->sem_nsems;
420 }
421 semaptr->sem_perm.mode = 0;
422 semundo_clear(semid, -1);
423 wakeup((caddr_t)semaptr);
424 break;
425
426 case IPC_SET:
427 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M)))
428 return(eval);
429 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
430 return(eval);
431 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
432 sizeof(sbuf))) != 0)
433 return(eval);
434 semaptr->sem_perm.uid = sbuf.sem_perm.uid;
435 semaptr->sem_perm.gid = sbuf.sem_perm.gid;
436 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
437 (sbuf.sem_perm.mode & 0777);
438 semaptr->sem_ctime = time_second;
439 break;
440
441 case IPC_STAT:
442 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
443 return(eval);
444 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
445 return(eval);
446 eval = copyout((caddr_t)semaptr, real_arg.buf,
447 sizeof(struct semid_ds));
448 break;
449
450 case GETNCNT:
451 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
452 return(eval);
453 if (semnum < 0 || semnum >= semaptr->sem_nsems)
454 return(EINVAL);
455 rval = semaptr->sem_base[semnum].semncnt;
456 break;
457
458 case GETPID:
459 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
460 return(eval);
461 if (semnum < 0 || semnum >= semaptr->sem_nsems)
462 return(EINVAL);
463 rval = semaptr->sem_base[semnum].sempid;
464 break;
465
466 case GETVAL:
467 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
468 return(eval);
469 if (semnum < 0 || semnum >= semaptr->sem_nsems)
470 return(EINVAL);
471 rval = semaptr->sem_base[semnum].semval;
472 break;
473
474 case GETALL:
475 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
476 return(eval);
477 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
478 return(eval);
479 for (i = 0; i < semaptr->sem_nsems; i++) {
480 eval = copyout((caddr_t)&semaptr->sem_base[i].semval,
481 &real_arg.array[i], sizeof(real_arg.array[0]));
482 if (eval != 0)
483 break;
484 }
485 break;
486
487 case GETZCNT:
488 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
489 return(eval);
490 if (semnum < 0 || semnum >= semaptr->sem_nsems)
491 return(EINVAL);
492 rval = semaptr->sem_base[semnum].semzcnt;
493 break;
494
495 case SETVAL:
496 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W)))
497 return(eval);
498 if (semnum < 0 || semnum >= semaptr->sem_nsems)
499 return(EINVAL);
500 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
501 return(eval);
502 semaptr->sem_base[semnum].semval = real_arg.val;
503 semundo_clear(semid, semnum);
504 wakeup((caddr_t)semaptr);
505 break;
506
507 case SETALL:
508 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W)))
509 return(eval);
510 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
511 return(eval);
512 for (i = 0; i < semaptr->sem_nsems; i++) {
513 eval = copyin(&real_arg.array[i],
514 (caddr_t)&semaptr->sem_base[i].semval,
515 sizeof(real_arg.array[0]));
516 if (eval != 0)
517 break;
518 }
519 semundo_clear(semid, -1);
520 wakeup((caddr_t)semaptr);
521 break;
522
523 default:
524 return(EINVAL);
525 }
526
527 if (eval == 0)
528 uap->sysmsg_result = rval;
529 return(eval);
530 }
531
532 int
533 sys_semget(struct semget_args *uap)
534 {
535 struct proc *p = curproc;
536 int semid, eval;
537 int key = uap->key;
538 int nsems = uap->nsems;
539 int semflg = uap->semflg;
540 struct ucred *cred = p->p_ucred;
541
542 #ifdef SEM_DEBUG
543 kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
544 #endif
545
546 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
547 return (ENOSYS);
548
549 if (key != IPC_PRIVATE) {
550 for (semid = 0; semid < seminfo.semmni; semid++) {
551 if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
552 sema[semid].sem_perm.key == key)
553 break;
554 }
555 if (semid < seminfo.semmni) {
556 #ifdef SEM_DEBUG
557 kprintf("found public key\n");
558 #endif
559 if ((eval = ipcperm(p, &sema[semid].sem_perm,
560 semflg & 0700)))
561 return(eval);
562 if (nsems > 0 && sema[semid].sem_nsems < nsems) {
563 #ifdef SEM_DEBUG
564 kprintf("too small\n");
565 #endif
566 return(EINVAL);
567 }
568 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
569 #ifdef SEM_DEBUG
570 kprintf("not exclusive\n");
571 #endif
572 return(EEXIST);
573 }
574 goto found;
575 }
576 }
577
578 #ifdef SEM_DEBUG
579 kprintf("need to allocate the semid_ds\n");
580 #endif
581 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
582 if (nsems <= 0 || nsems > seminfo.semmsl) {
583 #ifdef SEM_DEBUG
584 kprintf("nsems out of range (0<%d<=%d)\n", nsems,
585 seminfo.semmsl);
586 #endif
587 return(EINVAL);
588 }
589 if (nsems > seminfo.semmns - semtot) {
590 #ifdef SEM_DEBUG
591 kprintf("not enough semaphores left (need %d, got %d)\n",
592 nsems, seminfo.semmns - semtot);
593 #endif
594 return(ENOSPC);
595 }
596 for (semid = 0; semid < seminfo.semmni; semid++) {
597 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
598 break;
599 }
600 if (semid == seminfo.semmni) {
601 #ifdef SEM_DEBUG
602 kprintf("no more semid_ds's available\n");
603 #endif
604 return(ENOSPC);
605 }
606 #ifdef SEM_DEBUG
607 kprintf("semid %d is available\n", semid);
608 #endif
609 sema[semid].sem_perm.key = key;
610 sema[semid].sem_perm.cuid = cred->cr_uid;
611 sema[semid].sem_perm.uid = cred->cr_uid;
612 sema[semid].sem_perm.cgid = cred->cr_gid;
613 sema[semid].sem_perm.gid = cred->cr_gid;
614 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
615 sema[semid].sem_perm.seq =
616 (sema[semid].sem_perm.seq + 1) & 0x7fff;
617 sema[semid].sem_nsems = nsems;
618 sema[semid].sem_otime = 0;
619 sema[semid].sem_ctime = time_second;
620 sema[semid].sem_base = &sem[semtot];
621 semtot += nsems;
622 bzero(sema[semid].sem_base,
623 sizeof(sema[semid].sem_base[0])*nsems);
624 #ifdef SEM_DEBUG
625 kprintf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
626 &sem[semtot]);
627 #endif
628 } else {
629 #ifdef SEM_DEBUG
630 kprintf("didn't find it and wasn't asked to create it\n");
631 #endif
632 return(ENOENT);
633 }
634
635 found:
636 uap->sysmsg_result = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
637 return(0);
638 }
639
640 int
641 sys_semop(struct semop_args *uap)
642 {
643 struct proc *p = curproc;
644 int semid = uap->semid;
645 u_int nsops = uap->nsops;
646 struct sembuf sops[MAX_SOPS];
647 struct semid_ds *semaptr;
648 struct sembuf *sopptr;
649 struct sem *semptr;
650 struct sem_undo *suptr = NULL;
651 int i, j, eval;
652 int do_wakeup, do_undos;
653
654 #ifdef SEM_DEBUG
655 kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
656 #endif
657
658 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
659 return (ENOSYS);
660
661 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
662
663 if (semid < 0 || semid >= seminfo.semmni)
664 return(EINVAL);
665
666 semaptr = &sema[semid];
667 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
668 return(EINVAL);
669 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
670 return(EINVAL);
671
672 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) {
673 #ifdef SEM_DEBUG
674 kprintf("eval = %d from ipaccess\n", eval);
675 #endif
676 return(eval);
677 }
678
679 if (nsops > MAX_SOPS) {
680 #ifdef SEM_DEBUG
681 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops);
682 #endif
683 return(E2BIG);
684 }
685
686 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
687 #ifdef SEM_DEBUG
688 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval,
689 uap->sops, &sops, nsops * sizeof(sops[0]));
690 #endif
691 return(eval);
692 }
693
694 /*
695 * Loop trying to satisfy the vector of requests.
696 * If we reach a point where we must wait, any requests already
697 * performed are rolled back and we go to sleep until some other
698 * process wakes us up. At this point, we start all over again.
699 *
700 * This ensures that from the perspective of other tasks, a set
701 * of requests is atomic (never partially satisfied).
702 */
703 do_undos = 0;
704
705 for (;;) {
706 do_wakeup = 0;
707
708 for (i = 0; i < nsops; i++) {
709 sopptr = &sops[i];
710
711 if (sopptr->sem_num >= semaptr->sem_nsems)
712 return(EFBIG);
713
714 semptr = &semaptr->sem_base[sopptr->sem_num];
715
716 #ifdef SEM_DEBUG
717 kprintf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
718 semaptr, semaptr->sem_base, semptr,
719 sopptr->sem_num, semptr->semval, sopptr->sem_op,
720 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
721 #endif
722
723 if (sopptr->sem_op < 0) {
724 if (semptr->semval + sopptr->sem_op < 0) {
725 #ifdef SEM_DEBUG
726 kprintf("semop: can't do it now\n");
727 #endif
728 break;
729 } else {
730 semptr->semval += sopptr->sem_op;
731 if (semptr->semval == 0 &&
732 semptr->semzcnt > 0)
733 do_wakeup = 1;
734 }
735 if (sopptr->sem_flg & SEM_UNDO)
736 do_undos = 1;
737 } else if (sopptr->sem_op == 0) {
738 if (semptr->semval > 0) {
739 #ifdef SEM_DEBUG
740 kprintf("semop: not zero now\n");
741 #endif
742 break;
743 }
744 } else {
745 if (semptr->semncnt > 0)
746 do_wakeup = 1;
747 semptr->semval += sopptr->sem_op;
748 if (sopptr->sem_flg & SEM_UNDO)
749 do_undos = 1;
750 }
751 }
752
753 /*
754 * Did we get through the entire vector?
755 */
756 if (i >= nsops)
757 goto done;
758
759 /*
760 * No ... rollback anything that we've already done
761 */
762 #ifdef SEM_DEBUG
763 kprintf("semop: rollback 0 through %d\n", i-1);
764 #endif
765 for (j = 0; j < i; j++)
766 semaptr->sem_base[sops[j].sem_num].semval -=
767 sops[j].sem_op;
768
769 /*
770 * If the request that we couldn't satisfy has the
771 * NOWAIT flag set then return with EAGAIN.
772 */
773 if (sopptr->sem_flg & IPC_NOWAIT)
774 return(EAGAIN);
775
776 if (sopptr->sem_op == 0)
777 semptr->semzcnt++;
778 else
779 semptr->semncnt++;
780
781 #ifdef SEM_DEBUG
782 kprintf("semop: good night!\n");
783 #endif
784 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0);
785 #ifdef SEM_DEBUG
786 kprintf("semop: good morning (eval=%d)!\n", eval);
787 #endif
788
789 suptr = NULL; /* sem_undo may have been reallocated */
790
791 /* return code is checked below, after sem[nz]cnt-- */
792
793 /*
794 * Make sure that the semaphore still exists
795 */
796 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
797 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
798 return(EIDRM);
799
800 /*
801 * The semaphore is still alive. Readjust the count of
802 * waiting processes.
803 */
804 if (sopptr->sem_op == 0)
805 semptr->semzcnt--;
806 else
807 semptr->semncnt--;
808
809 /*
810 * Is it really morning, or was our sleep interrupted?
811 * (Delayed check of msleep() return code because we
812 * need to decrement sem[nz]cnt either way.)
813 */
814 if (eval != 0)
815 return(EINTR);
816 #ifdef SEM_DEBUG
817 kprintf("semop: good morning!\n");
818 #endif
819 }
820
821 done:
822 /*
823 * Process any SEM_UNDO requests.
824 */
825 if (do_undos) {
826 for (i = 0; i < nsops; i++) {
827 /*
828 * We only need to deal with SEM_UNDO's for non-zero
829 * op's.
830 */
831 int adjval;
832
833 if ((sops[i].sem_flg & SEM_UNDO) == 0)
834 continue;
835 adjval = sops[i].sem_op;
836 if (adjval == 0)
837 continue;
838 eval = semundo_adjust(p, &suptr, semid,
839 sops[i].sem_num, -adjval);
840 if (eval == 0)
841 continue;
842
843 /*
844 * Oh-Oh! We ran out of either sem_undo's or undo's.
845 * Rollback the adjustments to this point and then
846 * rollback the semaphore ups and down so we can return
847 * with an error with all structures restored. We
848 * rollback the undo's in the exact reverse order that
849 * we applied them. This guarantees that we won't run
850 * out of space as we roll things back out.
851 */
852 for (j = i - 1; j >= 0; j--) {
853 if ((sops[j].sem_flg & SEM_UNDO) == 0)
854 continue;
855 adjval = sops[j].sem_op;
856 if (adjval == 0)
857 continue;
858 if (semundo_adjust(p, &suptr, semid,
859 sops[j].sem_num, adjval) != 0)
860 panic("semop - can't undo undos");
861 }
862
863 for (j = 0; j < nsops; j++)
864 semaptr->sem_base[sops[j].sem_num].semval -=
865 sops[j].sem_op;
866
867 #ifdef SEM_DEBUG
868 kprintf("eval = %d from semundo_adjust\n", eval);
869 #endif
870 return(eval);
871 } /* loop through the sops */
872 } /* if (do_undos) */
873
874 /* We're definitely done - set the sempid's */
875 for (i = 0; i < nsops; i++) {
876 sopptr = &sops[i];
877 semptr = &semaptr->sem_base[sopptr->sem_num];
878 semptr->sempid = p->p_pid;
879 }
880
881 /* Do a wakeup if any semaphore was up'd. */
882 if (do_wakeup) {
883 #ifdef SEM_DEBUG
884 kprintf("semop: doing wakeup\n");
885 #endif
886 wakeup((caddr_t)semaptr);
887 #ifdef SEM_DEBUG
888 kprintf("semop: back from wakeup\n");
889 #endif
890 }
891 #ifdef SEM_DEBUG
892 kprintf("semop: done\n");
893 #endif
894 uap->sysmsg_result = 0;
895 return(0);
896 }
897
898 /*
899 * Go through the undo structures for this process and apply the adjustments to
900 * semaphores.
901 */
902 void
903 semexit(struct proc *p)
904 {
905 struct sem_undo *suptr;
906 struct sem_undo **supptr;
907 int did_something;
908
909 did_something = 0;
910
911 /*
912 * Go through the chain of undo vectors looking for one
913 * associated with this process.
914 */
915
916 for (supptr = &semu_list; (suptr = *supptr) != NULL;
917 supptr = &suptr->un_next) {
918 if (suptr->un_proc == p)
919 break;
920 }
921
922 if (suptr == NULL)
923 return;
924
925 #ifdef SEM_DEBUG
926 kprintf("proc @%08x has undo structure with %d entries\n", p,
927 suptr->un_cnt);
928 #endif
929
930 /*
931 * If there are any active undo elements then process them.
932 */
933 if (suptr->un_cnt > 0) {
934 int ix;
935
936 for (ix = 0; ix < suptr->un_cnt; ix++) {
937 int semid = suptr->un_ent[ix].un_id;
938 int semnum = suptr->un_ent[ix].un_num;
939 int adjval = suptr->un_ent[ix].un_adjval;
940 struct semid_ds *semaptr;
941
942 semaptr = &sema[semid];
943 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
944 panic("semexit - semid not allocated");
945 if (semnum >= semaptr->sem_nsems)
946 panic("semexit - semnum out of range");
947
948 #ifdef SEM_DEBUG
949 kprintf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n",
950 suptr->un_proc, suptr->un_ent[ix].un_id,
951 suptr->un_ent[ix].un_num,
952 suptr->un_ent[ix].un_adjval,
953 semaptr->sem_base[semnum].semval);
954 #endif
955
956 if (adjval < 0) {
957 if (semaptr->sem_base[semnum].semval < -adjval)
958 semaptr->sem_base[semnum].semval = 0;
959 else
960 semaptr->sem_base[semnum].semval +=
961 adjval;
962 } else
963 semaptr->sem_base[semnum].semval += adjval;
964
965 wakeup((caddr_t)semaptr);
966 #ifdef SEM_DEBUG
967 kprintf("semexit: back from wakeup\n");
968 #endif
969 }
970 }
971
972 /*
973 * Deallocate the undo vector.
974 */
975 #ifdef SEM_DEBUG
976 kprintf("removing vector\n");
977 #endif
978 suptr->un_proc = NULL;
979 *supptr = suptr->un_next;
980 }
DragonFly BSD