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kernel - Force NFSv3 for diskless nfs mount
[dragonfly.git] / sys / kern / sysv_sem.c
blobca0017bd10561d2873dfb5e85a045546528ef263
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 #include <sys/mplock2.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, struct sem_undo **supptr,
33 int semid, int semnum, int adjval);
34 static void semundo_clear (int semid, int semnum);
35
36 /* XXX casting to (sy_call_t *) is bogus, as usual. */
37 static sy_call_t *semcalls[] = {
38 (sy_call_t *)sys___semctl, (sy_call_t *)sys_semget,
39 (sy_call_t *)sys_semop
40 };
41
42 static int semtot = 0;
43 static struct semid_ds *sema; /* semaphore id pool */
44 static struct sem *sem; /* semaphore pool */
45 static struct sem_undo *semu_list; /* list of active undo structures */
46 static int *semu; /* undo structure pool */
47
48 struct sem {
49 u_short semval; /* semaphore value */
50 pid_t sempid; /* pid of last operation */
51 u_short semncnt; /* # awaiting semval > cval */
52 u_short semzcnt; /* # awaiting semval = 0 */
53 };
54
55 /*
56 * Undo structure (one per process)
57 */
58 struct sem_undo {
59 struct sem_undo *un_next; /* ptr to next active undo structure */
60 struct proc *un_proc; /* owner of this structure */
61 short un_cnt; /* # of active entries */
62 struct undo {
63 short un_adjval; /* adjust on exit values */
64 short un_num; /* semaphore # */
65 int un_id; /* semid */
66 } un_ent[1]; /* undo entries */
67 };
68
69 /*
70 * Configuration parameters
71 */
72 #ifndef SEMMNI
73 #define SEMMNI 10 /* # of semaphore identifiers */
74 #endif
75 #ifndef SEMMNS
76 #define SEMMNS 60 /* # of semaphores in system */
77 #endif
78 #ifndef SEMUME
79 #define SEMUME 10 /* max # of undo entries per process */
80 #endif
81 #ifndef SEMMNU
82 #define SEMMNU 30 /* # of undo structures in system */
83 #endif
84
85 /* shouldn't need tuning */
86 #ifndef SEMMAP
87 #define SEMMAP 30 /* # of entries in semaphore map */
88 #endif
89 #ifndef SEMMSL
90 #define SEMMSL SEMMNS /* max # of semaphores per id */
91 #endif
92 #ifndef SEMOPM
93 #define SEMOPM 100 /* max # of operations per semop call */
94 #endif
95
96 #define SEMVMX 32767 /* semaphore maximum value */
97 #define SEMAEM 16384 /* adjust on exit max value */
98
99 /*
100 * Due to the way semaphore memory is allocated, we have to ensure that
101 * SEMUSZ is properly aligned.
102 */
103
104 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
105
106 /* actual size of an undo structure */
107 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
108
109 /*
110 * Macro to find a particular sem_undo vector
111 */
112 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
113
114 /*
115 * semaphore info struct
116 */
117 struct seminfo seminfo = {
118 SEMMAP, /* # of entries in semaphore map */
119 SEMMNI, /* # of semaphore identifiers */
120 SEMMNS, /* # of semaphores in system */
121 SEMMNU, /* # of undo structures in system */
122 SEMMSL, /* max # of semaphores per id */
123 SEMOPM, /* max # of operations per semop call */
124 SEMUME, /* max # of undo entries per process */
125 SEMUSZ, /* size in bytes of undo structure */
126 SEMVMX, /* semaphore maximum value */
127 SEMAEM /* adjust on exit max value */
128 };
129
130 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap);
131 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni);
132 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns);
133 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu);
134 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl);
135 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm);
136 TUNABLE_INT("kern.ipc.semume", &seminfo.semume);
137 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz);
138 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx);
139 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem);
140
141 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "");
142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, "");
143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, "");
144 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, "");
145 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "");
146 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, "");
147 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, "");
148 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, "");
149 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "");
150 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "");
151
152 #if 0
153 RO seminfo.semmap /* SEMMAP unused */
154 RO seminfo.semmni
155 RO seminfo.semmns
156 RO seminfo.semmnu /* undo entries per system */
157 RW seminfo.semmsl
158 RO seminfo.semopm /* SEMOPM unused */
159 RO seminfo.semume
160 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */
161 RO seminfo.semvmx /* SEMVMX unused - user param */
162 RO seminfo.semaem /* SEMAEM unused - user param */
163 #endif
164
165 static void
166 seminit(void *dummy)
167 {
168 int i;
169
170 sem = kmalloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
171 sema = kmalloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK);
172 semu = kmalloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
173
174 for (i = 0; i < seminfo.semmni; i++) {
175 sema[i].sem_base = 0;
176 sema[i].sem_perm.mode = 0;
177 }
178 for (i = 0; i < seminfo.semmnu; i++) {
179 struct sem_undo *suptr = SEMU(i);
180 suptr->un_proc = NULL;
181 }
182 semu_list = NULL;
183 }
184 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
185
186 /*
187 * Entry point for all SEM calls
188 *
189 * semsys_args(int which, a2, a3, ...) (VARARGS)
190 *
191 * MPALMOSTSAFE
192 */
193 int
194 sys_semsys(struct semsys_args *uap)
195 {
196 struct thread *td = curthread;
197 unsigned int which = (unsigned int)uap->which;
198 int error;
199
200 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
201 return (ENOSYS);
202
203 if (which >= sizeof(semcalls)/sizeof(semcalls[0]))
204 return (EINVAL);
205 bcopy(&uap->a2, &uap->which,
206 sizeof(struct semsys_args) - offsetof(struct semsys_args, a2));
207 get_mplock();
208 error = (*semcalls[which])(uap);
209 rel_mplock();
210 return (error);
211 }
212
213 /*
214 * Allocate a new sem_undo structure for a process
215 * (returns ptr to structure or NULL if no more room)
216 */
217
218 static struct sem_undo *
219 semu_alloc(struct proc *p)
220 {
221 int i;
222 struct sem_undo *suptr;
223 struct sem_undo **supptr;
224 int attempt;
225
226 /*
227 * Try twice to allocate something.
228 * (we'll purge any empty structures after the first pass so
229 * two passes are always enough)
230 */
231
232 for (attempt = 0; attempt < 2; attempt++) {
233 /*
234 * Look for a free structure.
235 * Fill it in and return it if we find one.
236 */
237
238 for (i = 0; i < seminfo.semmnu; i++) {
239 suptr = SEMU(i);
240 if (suptr->un_proc == NULL) {
241 suptr->un_next = semu_list;
242 semu_list = suptr;
243 suptr->un_cnt = 0;
244 suptr->un_proc = p;
245 return(suptr);
246 }
247 }
248
249 /*
250 * We didn't find a free one, if this is the first attempt
251 * then try to free some structures.
252 */
253
254 if (attempt == 0) {
255 /* All the structures are in use - try to free some */
256 int did_something = 0;
257
258 supptr = &semu_list;
259 while ((suptr = *supptr) != NULL) {
260 if (suptr->un_cnt == 0) {
261 suptr->un_proc = NULL;
262 *supptr = suptr->un_next;
263 did_something = 1;
264 } else
265 supptr = &(suptr->un_next);
266 }
267
268 /* If we didn't free anything then just give-up */
269 if (!did_something)
270 return(NULL);
271 } else {
272 /*
273 * The second pass failed even though we freed
274 * something after the first pass!
275 * This is IMPOSSIBLE!
276 */
277 panic("semu_alloc - second attempt failed");
278 }
279 }
280 return (NULL);
281 }
282
283 /*
284 * Adjust a particular entry for a particular proc
285 */
286
287 static int
288 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
289 int adjval)
290 {
291 struct sem_undo *suptr;
292 struct undo *sunptr;
293 int i;
294
295 /* Look for and remember the sem_undo if the caller doesn't provide
296 it */
297
298 suptr = *supptr;
299 if (suptr == NULL) {
300 for (suptr = semu_list; suptr != NULL;
301 suptr = suptr->un_next) {
302 if (suptr->un_proc == p) {
303 *supptr = suptr;
304 break;
305 }
306 }
307 if (suptr == NULL) {
308 if (adjval == 0)
309 return(0);
310 suptr = semu_alloc(p);
311 if (suptr == NULL)
312 return(ENOSPC);
313 *supptr = suptr;
314 }
315 }
316
317 /*
318 * Look for the requested entry and adjust it (delete if adjval becomes
319 * 0).
320 */
321 sunptr = &suptr->un_ent[0];
322 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
323 if (sunptr->un_id != semid || sunptr->un_num != semnum)
324 continue;
325 if (adjval == 0)
326 sunptr->un_adjval = 0;
327 else
328 sunptr->un_adjval += adjval;
329 if (sunptr->un_adjval == 0) {
330 suptr->un_cnt--;
331 if (i < suptr->un_cnt)
332 suptr->un_ent[i] =
333 suptr->un_ent[suptr->un_cnt];
334 }
335 return(0);
336 }
337
338 /* Didn't find the right entry - create it */
339 if (adjval == 0)
340 return(0);
341 if (suptr->un_cnt != seminfo.semume) {
342 sunptr = &suptr->un_ent[suptr->un_cnt];
343 suptr->un_cnt++;
344 sunptr->un_adjval = adjval;
345 sunptr->un_id = semid; sunptr->un_num = semnum;
346 } else
347 return(EINVAL);
348 return(0);
349 }
350
351 static void
352 semundo_clear(int semid, int semnum)
353 {
354 struct sem_undo *suptr;
355
356 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
357 struct undo *sunptr = &suptr->un_ent[0];
358 int i = 0;
359
360 while (i < suptr->un_cnt) {
361 if (sunptr->un_id == semid) {
362 if (semnum == -1 || sunptr->un_num == semnum) {
363 suptr->un_cnt--;
364 if (i < suptr->un_cnt) {
365 suptr->un_ent[i] =
366 suptr->un_ent[suptr->un_cnt];
367 continue;
368 }
369 }
370 if (semnum != -1)
371 break;
372 }
373 i++, sunptr++;
374 }
375 }
376 }
377
378 /*
379 * Note that the user-mode half of this passes a union, not a pointer
380 *
381 * MPALMOSTSAFE
382 */
383 int
384 sys___semctl(struct __semctl_args *uap)
385 {
386 struct thread *td = curthread;
387 int semid = uap->semid;
388 int semnum = uap->semnum;
389 int cmd = uap->cmd;
390 union semun *arg = uap->arg;
391 union semun real_arg;
392 struct ucred *cred = td->td_ucred;
393 int i, rval, eval;
394 struct semid_ds sbuf;
395 struct semid_ds *semaptr;
396 struct semid_ds *semakptr;
397
398 #ifdef SEM_DEBUG
399 kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
400 #endif
401
402 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
403 return (ENOSYS);
404
405 get_mplock();
406 switch (cmd) {
407 case SEM_STAT:
408 /*
409 * For this command we assume semid is an array index
410 * rather than an IPC id.
411 */
412 if (semid < 0 || semid >= seminfo.semmni) {
413 eval = EINVAL;
414 break;
415 }
416 semakptr = &sema[semid];
417 if ((semakptr->sem_perm.mode & SEM_ALLOC) == 0) {
418 eval = EINVAL;
419 break;
420 }
421 if ((eval = ipcperm(td->td_proc, &semakptr->sem_perm, IPC_R)))
422 break;
423
424 bcopy(&semakptr, arg->buf, sizeof(struct semid_ds));
425 rval = IXSEQ_TO_IPCID(semid, semakptr->sem_perm);
426 break;
427 }
428
429 semid = IPCID_TO_IX(semid);
430 if (semid < 0 || semid >= seminfo.semmni) {
431 rel_mplock();
432 return(EINVAL);
433 }
434
435 semaptr = &sema[semid];
436 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
437 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
438 rel_mplock();
439 return(EINVAL);
440 }
441
442 eval = 0;
443 rval = 0;
444
445 switch (cmd) {
446 case IPC_RMID:
447 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_M)) != 0)
448 break;
449 semaptr->sem_perm.cuid = cred->cr_uid;
450 semaptr->sem_perm.uid = cred->cr_uid;
451 semtot -= semaptr->sem_nsems;
452 for (i = semaptr->sem_base - sem; i < semtot; i++)
453 sem[i] = sem[i + semaptr->sem_nsems];
454 for (i = 0; i < seminfo.semmni; i++) {
455 if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
456 sema[i].sem_base > semaptr->sem_base)
457 sema[i].sem_base -= semaptr->sem_nsems;
458 }
459 semaptr->sem_perm.mode = 0;
460 semundo_clear(semid, -1);
461 wakeup((caddr_t)semaptr);
462 break;
463
464 case IPC_SET:
465 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_M);
466 if (eval)
467 break;
468 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
469 break;
470 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
471 sizeof(sbuf))) != 0) {
472 break;
473 }
474 semaptr->sem_perm.uid = sbuf.sem_perm.uid;
475 semaptr->sem_perm.gid = sbuf.sem_perm.gid;
476 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
477 (sbuf.sem_perm.mode & 0777);
478 semaptr->sem_ctime = time_second;
479 break;
480
481 case IPC_STAT:
482 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R)))
483 break;
484 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
485 break;
486 eval = copyout(semaptr, real_arg.buf, sizeof(struct semid_ds));
487 break;
488
489 case GETNCNT:
490 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
491 if (eval)
492 break;
493 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
494 eval = EINVAL;
495 break;
496 }
497 rval = semaptr->sem_base[semnum].semncnt;
498 break;
499
500 case GETPID:
501 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
502 if (eval)
503 break;
504 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
505 eval = EINVAL;
506 break;
507 }
508 rval = semaptr->sem_base[semnum].sempid;
509 break;
510
511 case GETVAL:
512 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
513 if (eval)
514 break;
515 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
516 eval = EINVAL;
517 break;
518 }
519 rval = semaptr->sem_base[semnum].semval;
520 break;
521
522 case GETALL:
523 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
524 if (eval)
525 break;
526 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
527 break;
528 for (i = 0; i < semaptr->sem_nsems; i++) {
529 eval = copyout(&semaptr->sem_base[i].semval,
530 &real_arg.array[i],
531 sizeof(real_arg.array[0]));
532 if (eval)
533 break;
534 }
535 break;
536
537 case GETZCNT:
538 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_R);
539 if (eval)
540 break;
541 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
542 eval = EINVAL;
543 break;
544 }
545 rval = semaptr->sem_base[semnum].semzcnt;
546 break;
547
548 case SETVAL:
549 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W);
550 if (eval)
551 break;
552 if (semnum < 0 || semnum >= semaptr->sem_nsems) {
553 eval = EINVAL;
554 break;
555 }
556 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
557 break;
558 semaptr->sem_base[semnum].semval = real_arg.val;
559 semundo_clear(semid, semnum);
560 wakeup((caddr_t)semaptr);
561 break;
562
563 case SETALL:
564 eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W);
565 if (eval)
566 break;
567 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
568 break;
569 for (i = 0; i < semaptr->sem_nsems; i++) {
570 eval = copyin(&real_arg.array[i],
571 (caddr_t)&semaptr->sem_base[i].semval,
572 sizeof(real_arg.array[0]));
573 if (eval != 0)
574 break;
575 }
576 semundo_clear(semid, -1);
577 wakeup((caddr_t)semaptr);
578 break;
579
580 default:
581 eval = EINVAL;
582 break;
583 }
584 rel_mplock();
585
586 if (eval == 0)
587 uap->sysmsg_result = rval;
588 return(eval);
589 }
590
591 /*
592 * MPALMOSTSAFE
593 */
594 int
595 sys_semget(struct semget_args *uap)
596 {
597 struct thread *td = curthread;
598 int semid, eval;
599 int key = uap->key;
600 int nsems = uap->nsems;
601 int semflg = uap->semflg;
602 struct ucred *cred = td->td_ucred;
603
604 #ifdef SEM_DEBUG
605 kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
606 #endif
607
608 if (!jail_sysvipc_allowed && cred->cr_prison != NULL)
609 return (ENOSYS);
610
611 get_mplock();
612 eval = 0;
613
614 if (key != IPC_PRIVATE) {
615 for (semid = 0; semid < seminfo.semmni; semid++) {
616 if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
617 sema[semid].sem_perm.key == key)
618 break;
619 }
620 if (semid < seminfo.semmni) {
621 #ifdef SEM_DEBUG
622 kprintf("found public key\n");
623 #endif
624 if ((eval = ipcperm(td->td_proc,
625 &sema[semid].sem_perm,
626 semflg & 0700))) {
627 goto done;
628 }
629 if (nsems > 0 && sema[semid].sem_nsems < nsems) {
630 #ifdef SEM_DEBUG
631 kprintf("too small\n");
632 #endif
633 eval = EINVAL;
634 goto done;
635 }
636 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
637 #ifdef SEM_DEBUG
638 kprintf("not exclusive\n");
639 #endif
640 eval = EEXIST;
641 goto done;
642 }
643 goto done;
644 }
645 }
646
647 #ifdef SEM_DEBUG
648 kprintf("need to allocate the semid_ds\n");
649 #endif
650 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
651 if (nsems <= 0 || nsems > seminfo.semmsl) {
652 #ifdef SEM_DEBUG
653 kprintf("nsems out of range (0<%d<=%d)\n", nsems,
654 seminfo.semmsl);
655 #endif
656 eval = EINVAL;
657 goto done;
658 }
659 if (nsems > seminfo.semmns - semtot) {
660 #ifdef SEM_DEBUG
661 kprintf("not enough semaphores left (need %d, got %d)\n",
662 nsems, seminfo.semmns - semtot);
663 #endif
664 eval = ENOSPC;
665 goto done;
666 }
667 for (semid = 0; semid < seminfo.semmni; semid++) {
668 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
669 break;
670 }
671 if (semid == seminfo.semmni) {
672 #ifdef SEM_DEBUG
673 kprintf("no more semid_ds's available\n");
674 #endif
675 eval = ENOSPC;
676 goto done;
677 }
678 #ifdef SEM_DEBUG
679 kprintf("semid %d is available\n", semid);
680 #endif
681 sema[semid].sem_perm.key = key;
682 sema[semid].sem_perm.cuid = cred->cr_uid;
683 sema[semid].sem_perm.uid = cred->cr_uid;
684 sema[semid].sem_perm.cgid = cred->cr_gid;
685 sema[semid].sem_perm.gid = cred->cr_gid;
686 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
687 sema[semid].sem_perm.seq =
688 (sema[semid].sem_perm.seq + 1) & 0x7fff;
689 sema[semid].sem_nsems = nsems;
690 sema[semid].sem_otime = 0;
691 sema[semid].sem_ctime = time_second;
692 sema[semid].sem_base = &sem[semtot];
693 semtot += nsems;
694 bzero(sema[semid].sem_base,
695 sizeof(sema[semid].sem_base[0])*nsems);
696 #ifdef SEM_DEBUG
697 kprintf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
698 &sem[semtot]);
699 #endif
700 } else {
701 #ifdef SEM_DEBUG
702 kprintf("didn't find it and wasn't asked to create it\n");
703 #endif
704 eval = ENOENT;
705 }
706
707 done:
708 if (eval == 0) {
709 uap->sysmsg_result = IXSEQ_TO_IPCID(semid,
710 sema[semid].sem_perm);
711 }
712 rel_mplock();
713 return(eval);
714 }
715
716 /*
717 * MPALMOSTSAFE
718 */
719 int
720 sys_semop(struct semop_args *uap)
721 {
722 struct thread *td = curthread;
723 int semid = uap->semid;
724 u_int nsops = uap->nsops;
725 struct sembuf sops[MAX_SOPS];
726 struct semid_ds *semaptr;
727 struct sembuf *sopptr;
728 struct sem *semptr;
729 struct sem_undo *suptr = NULL;
730 int i, j, eval;
731 int do_wakeup, do_undos;
732
733 #ifdef SEM_DEBUG
734 kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
735 #endif
736
737 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
738 return (ENOSYS);
739
740 get_mplock();
741 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
742
743 if (semid < 0 || semid >= seminfo.semmni) {
744 eval = EINVAL;
745 goto done;
746 }
747
748 semaptr = &sema[semid];
749 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) {
750 eval = EINVAL;
751 goto done;
752 }
753 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
754 eval = EINVAL;
755 goto done;
756 }
757
758 if ((eval = ipcperm(td->td_proc, &semaptr->sem_perm, IPC_W))) {
759 #ifdef SEM_DEBUG
760 kprintf("eval = %d from ipaccess\n", eval);
761 #endif
762 goto done;
763 }
764
765 if (nsops > MAX_SOPS) {
766 #ifdef SEM_DEBUG
767 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops);
768 #endif
769 eval = E2BIG;
770 goto done;
771 }
772
773 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
774 #ifdef SEM_DEBUG
775 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval,
776 uap->sops, &sops, nsops * sizeof(sops[0]));
777 #endif
778 goto done;
779 }
780
781 /*
782 * Loop trying to satisfy the vector of requests.
783 * If we reach a point where we must wait, any requests already
784 * performed are rolled back and we go to sleep until some other
785 * process wakes us up. At this point, we start all over again.
786 *
787 * This ensures that from the perspective of other tasks, a set
788 * of requests is atomic (never partially satisfied).
789 */
790 do_undos = 0;
791
792 for (;;) {
793 do_wakeup = 0;
794
795 for (i = 0; i < nsops; i++) {
796 sopptr = &sops[i];
797
798 if (sopptr->sem_num >= semaptr->sem_nsems) {
799 eval = EFBIG;
800 goto done;
801 }
802
803 semptr = &semaptr->sem_base[sopptr->sem_num];
804
805 #ifdef SEM_DEBUG
806 kprintf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
807 semaptr, semaptr->sem_base, semptr,
808 sopptr->sem_num, semptr->semval, sopptr->sem_op,
809 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
810 #endif
811
812 if (sopptr->sem_op < 0) {
813 if (semptr->semval + sopptr->sem_op < 0) {
814 #ifdef SEM_DEBUG
815 kprintf("semop: can't do it now\n");
816 #endif
817 break;
818 } else {
819 semptr->semval += sopptr->sem_op;
820 if (semptr->semval == 0 &&
821 semptr->semzcnt > 0)
822 do_wakeup = 1;
823 }
824 if (sopptr->sem_flg & SEM_UNDO)
825 do_undos = 1;
826 } else if (sopptr->sem_op == 0) {
827 if (semptr->semval > 0) {
828 #ifdef SEM_DEBUG
829 kprintf("semop: not zero now\n");
830 #endif
831 break;
832 }
833 } else {
834 if (semptr->semncnt > 0)
835 do_wakeup = 1;
836 semptr->semval += sopptr->sem_op;
837 if (sopptr->sem_flg & SEM_UNDO)
838 do_undos = 1;
839 }
840 }
841
842 /*
843 * Did we get through the entire vector?
844 */
845 if (i >= nsops)
846 goto donex;
847
848 /*
849 * No ... rollback anything that we've already done
850 */
851 #ifdef SEM_DEBUG
852 kprintf("semop: rollback 0 through %d\n", i-1);
853 #endif
854 for (j = 0; j < i; j++)
855 semaptr->sem_base[sops[j].sem_num].semval -=
856 sops[j].sem_op;
857
858 /*
859 * If the request that we couldn't satisfy has the
860 * NOWAIT flag set then return with EAGAIN.
861 */
862 if (sopptr->sem_flg & IPC_NOWAIT) {
863 eval = EAGAIN;
864 goto done;
865 }
866
867 if (sopptr->sem_op == 0)
868 semptr->semzcnt++;
869 else
870 semptr->semncnt++;
871
872 #ifdef SEM_DEBUG
873 kprintf("semop: good night!\n");
874 #endif
875 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0);
876 #ifdef SEM_DEBUG
877 kprintf("semop: good morning (eval=%d)!\n", eval);
878 #endif
879
880 suptr = NULL; /* sem_undo may have been reallocated */
881
882 /* return code is checked below, after sem[nz]cnt-- */
883
884 /*
885 * Make sure that the semaphore still exists
886 */
887 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
888 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
889 eval = EIDRM;
890 goto done;
891 }
892
893 /*
894 * The semaphore is still alive. Readjust the count of
895 * waiting processes.
896 */
897 if (sopptr->sem_op == 0)
898 semptr->semzcnt--;
899 else
900 semptr->semncnt--;
901
902 /*
903 * Is it really morning, or was our sleep interrupted?
904 * (Delayed check of tsleep() return code because we
905 * need to decrement sem[nz]cnt either way.)
906 */
907 if (eval) {
908 eval = EINTR;
909 goto done;
910 }
911 #ifdef SEM_DEBUG
912 kprintf("semop: good morning!\n");
913 #endif
914 }
915
916 donex:
917 /*
918 * Process any SEM_UNDO requests.
919 */
920 if (do_undos) {
921 for (i = 0; i < nsops; i++) {
922 /*
923 * We only need to deal with SEM_UNDO's for non-zero
924 * op's.
925 */
926 int adjval;
927
928 if ((sops[i].sem_flg & SEM_UNDO) == 0)
929 continue;
930 adjval = sops[i].sem_op;
931 if (adjval == 0)
932 continue;
933 eval = semundo_adjust(td->td_proc, &suptr, semid,
934 sops[i].sem_num, -adjval);
935 if (eval == 0)
936 continue;
937
938 /*
939 * Oh-Oh! We ran out of either sem_undo's or undo's.
940 * Rollback the adjustments to this point and then
941 * rollback the semaphore ups and down so we can return
942 * with an error with all structures restored. We
943 * rollback the undo's in the exact reverse order that
944 * we applied them. This guarantees that we won't run
945 * out of space as we roll things back out.
946 */
947 for (j = i - 1; j >= 0; j--) {
948 if ((sops[j].sem_flg & SEM_UNDO) == 0)
949 continue;
950 adjval = sops[j].sem_op;
951 if (adjval == 0)
952 continue;
953 if (semundo_adjust(td->td_proc, &suptr, semid,
954 sops[j].sem_num, adjval) != 0)
955 panic("semop - can't undo undos");
956 }
957
958 for (j = 0; j < nsops; j++)
959 semaptr->sem_base[sops[j].sem_num].semval -=
960 sops[j].sem_op;
961
962 #ifdef SEM_DEBUG
963 kprintf("eval = %d from semundo_adjust\n", eval);
964 #endif
965 goto done;
966 } /* loop through the sops */
967 } /* if (do_undos) */
968
969 /* We're definitely done - set the sempid's */
970 for (i = 0; i < nsops; i++) {
971 sopptr = &sops[i];
972 semptr = &semaptr->sem_base[sopptr->sem_num];
973 semptr->sempid = td->td_proc->p_pid;
974 }
975
976 /* Do a wakeup if any semaphore was up'd. */
977 if (do_wakeup) {
978 #ifdef SEM_DEBUG
979 kprintf("semop: doing wakeup\n");
980 #endif
981 wakeup((caddr_t)semaptr);
982 #ifdef SEM_DEBUG
983 kprintf("semop: back from wakeup\n");
984 #endif
985 }
986 #ifdef SEM_DEBUG
987 kprintf("semop: done\n");
988 #endif
989 uap->sysmsg_result = 0;
990 eval = 0;
991 done:
992 rel_mplock();
993 return(eval);
994 }
995
996 /*
997 * Go through the undo structures for this process and apply the adjustments to
998 * semaphores.
999 */
1000 void
1001 semexit(struct proc *p)
1002 {
1003 struct sem_undo *suptr;
1004 struct sem_undo **supptr;
1005 int did_something;
1006
1007 did_something = 0;
1008
1009 /*
1010 * Go through the chain of undo vectors looking for one
1011 * associated with this process.
1012 */
1013
1014 for (supptr = &semu_list; (suptr = *supptr) != NULL;
1015 supptr = &suptr->un_next) {
1016 if (suptr->un_proc == p)
1017 break;
1018 }
1019
1020 if (suptr == NULL)
1021 return;
1022
1023 #ifdef SEM_DEBUG
1024 kprintf("proc @%08x has undo structure with %d entries\n", p,
1025 suptr->un_cnt);
1026 #endif
1027
1028 /*
1029 * If there are any active undo elements then process them.
1030 */
1031 if (suptr->un_cnt > 0) {
1032 int ix;
1033
1034 for (ix = 0; ix < suptr->un_cnt; ix++) {
1035 int semid = suptr->un_ent[ix].un_id;
1036 int semnum = suptr->un_ent[ix].un_num;
1037 int adjval = suptr->un_ent[ix].un_adjval;
1038 struct semid_ds *semaptr;
1039
1040 semaptr = &sema[semid];
1041 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
1042 panic("semexit - semid not allocated");
1043 if (semnum >= semaptr->sem_nsems)
1044 panic("semexit - semnum out of range");
1045
1046 #ifdef SEM_DEBUG
1047 kprintf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n",
1048 suptr->un_proc, suptr->un_ent[ix].un_id,
1049 suptr->un_ent[ix].un_num,
1050 suptr->un_ent[ix].un_adjval,
1051 semaptr->sem_base[semnum].semval);
1052 #endif
1053
1054 if (adjval < 0) {
1055 if (semaptr->sem_base[semnum].semval < -adjval)
1056 semaptr->sem_base[semnum].semval = 0;
1057 else
1058 semaptr->sem_base[semnum].semval +=
1059 adjval;
1060 } else
1061 semaptr->sem_base[semnum].semval += adjval;
1062
1063 wakeup((caddr_t)semaptr);
1064 #ifdef SEM_DEBUG
1065 kprintf("semexit: back from wakeup\n");
1066 #endif
1067 }
1068 }
1069
1070 /*
1071 * Deallocate the undo vector.
1072 */
1073 #ifdef SEM_DEBUG
1074 kprintf("removing vector\n");
1075 #endif
1076 suptr->un_proc = NULL;
1077 *supptr = suptr->un_next;
1078 }
DragonFly BSD