Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/ipc/sem.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 34500 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
2 | * linux/ipc/sem.c |
3 | * Copyright (C) 1992 Krishna Balasubramanian |
4 | * Copyright (C) 1995 Eric Schenk, Bruno Haible |
5 | * |
6 | * IMPLEMENTATION NOTES ON CODE REWRITE (Eric Schenk, January 1995): |
7 | * This code underwent a massive rewrite in order to solve some problems |
8 | * with the original code. In particular the original code failed to |
9 | * wake up processes that were waiting for semval to go to 0 if the |
10 | * value went to 0 and was then incremented rapidly enough. In solving |
11 | * this problem I have also modified the implementation so that it |
12 | * processes pending operations in a FIFO manner, thus give a guarantee |
13 | * that processes waiting for a lock on the semaphore won't starve |
14 | * unless another locking process fails to unlock. |
15 | * In addition the following two changes in behavior have been introduced: |
16 | * - The original implementation of semop returned the value |
17 | * last semaphore element examined on success. This does not |
18 | * match the manual page specifications, and effectively |
19 | * allows the user to read the semaphore even if they do not |
20 | * have read permissions. The implementation now returns 0 |
21 | * on success as stated in the manual page. |
22 | * - There is some confusion over whether the set of undo adjustments |
23 | * to be performed at exit should be done in an atomic manner. |
24 | * That is, if we are attempting to decrement the semval should we queue |
25 | * up and wait until we can do so legally? |
26 | * The original implementation attempted to do this. |
27 | * The current implementation does not do so. This is because I don't |
28 | * think it is the right thing (TM) to do, and because I couldn't |
29 | * see a clean way to get the old behavior with the new design. |
30 | * The POSIX standard and SVID should be consulted to determine |
31 | * what behavior is mandated. |
32 | * |
33 | * Further notes on refinement (Christoph Rohland, December 1998): |
34 | * - The POSIX standard says, that the undo adjustments simply should |
35 | * redo. So the current implementation is o.K. |
36 | * - The previous code had two flaws: |
37 | * 1) It actively gave the semaphore to the next waiting process |
38 | * sleeping on the semaphore. Since this process did not have the |
39 | * cpu this led to many unnecessary context switches and bad |
40 | * performance. Now we only check which process should be able to |
41 | * get the semaphore and if this process wants to reduce some |
42 | * semaphore value we simply wake it up without doing the |
43 | * operation. So it has to try to get it later. Thus e.g. the |
44 | * running process may reacquire the semaphore during the current |
45 | * time slice. If it only waits for zero or increases the semaphore, |
46 | * we do the operation in advance and wake it up. |
47 | * 2) It did not wake up all zero waiting processes. We try to do |
48 | * better but only get the semops right which only wait for zero or |
49 | * increase. If there are decrement operations in the operations |
50 | * array we do the same as before. |
51 | * |
52 | * With the incarnation of O(1) scheduler, it becomes unnecessary to perform |
53 | * check/retry algorithm for waking up blocked processes as the new scheduler |
54 | * is better at handling thread switch than the old one. |
55 | * |
56 | * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
57 | * |
58 | * SMP-threaded, sysctl's added |
59 | * (c) 1999 Manfred Spraul <manfreds@colorfullife.com> |
60 | * Enforced range limit on SEM_UNDO |
61 | * (c) 2001 Red Hat Inc <alan@redhat.com> |
62 | * Lockless wakeup |
63 | * (c) 2003 Manfred Spraul <manfred@colorfullife.com> |
64 | */ |
65 | |
66 | #include <linux/config.h> |
67 | #include <linux/slab.h> |
68 | #include <linux/spinlock.h> |
69 | #include <linux/init.h> |
70 | #include <linux/proc_fs.h> |
71 | #include <linux/time.h> |
72 | #include <linux/smp_lock.h> |
73 | #include <linux/security.h> |
74 | #include <linux/syscalls.h> |
75 | #include <linux/audit.h> |
76 | #include <asm/uaccess.h> |
77 | #include "util.h" |
78 | |
79 | |
80 | #define sem_lock(id) ((struct sem_array*)ipc_lock(&sem_ids,id)) |
81 | #define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm) |
82 | #define sem_rmid(id) ((struct sem_array*)ipc_rmid(&sem_ids,id)) |
83 | #define sem_checkid(sma, semid) \ |
84 | ipc_checkid(&sem_ids,&sma->sem_perm,semid) |
85 | #define sem_buildid(id, seq) \ |
86 | ipc_buildid(&sem_ids, id, seq) |
87 | static struct ipc_ids sem_ids; |
88 | |
89 | static int newary (key_t, int, int); |
90 | static void freeary (struct sem_array *sma, int id); |
91 | #ifdef CONFIG_PROC_FS |
92 | static int sysvipc_sem_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data); |
93 | #endif |
94 | |
95 | #define SEMMSL_FAST 256 /* 512 bytes on stack */ |
96 | #define SEMOPM_FAST 64 /* ~ 372 bytes on stack */ |
97 | |
98 | /* |
99 | * linked list protection: |
100 | * sem_undo.id_next, |
101 | * sem_array.sem_pending{,last}, |
102 | * sem_array.sem_undo: sem_lock() for read/write |
103 | * sem_undo.proc_next: only "current" is allowed to read/write that field. |
104 | * |
105 | */ |
106 | |
107 | int sem_ctls[4] = {SEMMSL, SEMMNS, SEMOPM, SEMMNI}; |
108 | #define sc_semmsl (sem_ctls[0]) |
109 | #define sc_semmns (sem_ctls[1]) |
110 | #define sc_semopm (sem_ctls[2]) |
111 | #define sc_semmni (sem_ctls[3]) |
112 | |
113 | static int used_sems; |
114 | |
115 | void __init sem_init (void) |
116 | { |
117 | used_sems = 0; |
118 | ipc_init_ids(&sem_ids,sc_semmni); |
119 | |
120 | #ifdef CONFIG_PROC_FS |
121 | create_proc_read_entry("sysvipc/sem", 0, NULL, sysvipc_sem_read_proc, NULL); |
122 | #endif |
123 | } |
124 | |
125 | /* |
126 | * Lockless wakeup algorithm: |
127 | * Without the check/retry algorithm a lockless wakeup is possible: |
128 | * - queue.status is initialized to -EINTR before blocking. |
129 | * - wakeup is performed by |
130 | * * unlinking the queue entry from sma->sem_pending |
131 | * * setting queue.status to IN_WAKEUP |
132 | * This is the notification for the blocked thread that a |
133 | * result value is imminent. |
134 | * * call wake_up_process |
135 | * * set queue.status to the final value. |
136 | * - the previously blocked thread checks queue.status: |
137 | * * if it's IN_WAKEUP, then it must wait until the value changes |
138 | * * if it's not -EINTR, then the operation was completed by |
139 | * update_queue. semtimedop can return queue.status without |
140 | * performing any operation on the semaphore array. |
141 | * * otherwise it must acquire the spinlock and check what's up. |
142 | * |
143 | * The two-stage algorithm is necessary to protect against the following |
144 | * races: |
145 | * - if queue.status is set after wake_up_process, then the woken up idle |
146 | * thread could race forward and try (and fail) to acquire sma->lock |
147 | * before update_queue had a chance to set queue.status |
148 | * - if queue.status is written before wake_up_process and if the |
149 | * blocked process is woken up by a signal between writing |
150 | * queue.status and the wake_up_process, then the woken up |
151 | * process could return from semtimedop and die by calling |
152 | * sys_exit before wake_up_process is called. Then wake_up_process |
153 | * will oops, because the task structure is already invalid. |
154 | * (yes, this happened on s390 with sysv msg). |
155 | * |
156 | */ |
157 | #define IN_WAKEUP 1 |
158 | |
159 | static int newary (key_t key, int nsems, int semflg) |
160 | { |
161 | int id; |
162 | int retval; |
163 | struct sem_array *sma; |
164 | int size; |
165 | |
166 | if (!nsems) |
167 | return -EINVAL; |
168 | if (used_sems + nsems > sc_semmns) |
169 | return -ENOSPC; |
170 | |
171 | size = sizeof (*sma) + nsems * sizeof (struct sem); |
172 | sma = ipc_rcu_alloc(size); |
173 | if (!sma) { |
174 | return -ENOMEM; |
175 | } |
176 | memset (sma, 0, size); |
177 | |
178 | sma->sem_perm.mode = (semflg & S_IRWXUGO); |
179 | sma->sem_perm.key = key; |
180 | |
181 | sma->sem_perm.security = NULL; |
182 | retval = security_sem_alloc(sma); |
183 | if (retval) { |
184 | ipc_rcu_putref(sma); |
185 | return retval; |
186 | } |
187 | |
188 | id = ipc_addid(&sem_ids, &sma->sem_perm, sc_semmni); |
189 | if(id == -1) { |
190 | security_sem_free(sma); |
191 | ipc_rcu_putref(sma); |
192 | return -ENOSPC; |
193 | } |
194 | used_sems += nsems; |
195 | |
196 | sma->sem_base = (struct sem *) &sma[1]; |
197 | /* sma->sem_pending = NULL; */ |
198 | sma->sem_pending_last = &sma->sem_pending; |
199 | /* sma->undo = NULL; */ |
200 | sma->sem_nsems = nsems; |
201 | sma->sem_ctime = get_seconds(); |
202 | sem_unlock(sma); |
203 | |
204 | return sem_buildid(id, sma->sem_perm.seq); |
205 | } |
206 | |
207 | asmlinkage long sys_semget (key_t key, int nsems, int semflg) |
208 | { |
209 | int id, err = -EINVAL; |
210 | struct sem_array *sma; |
211 | |
212 | if (nsems < 0 || nsems > sc_semmsl) |
213 | return -EINVAL; |
214 | down(&sem_ids.sem); |
215 | |
216 | if (key == IPC_PRIVATE) { |
217 | err = newary(key, nsems, semflg); |
218 | } else if ((id = ipc_findkey(&sem_ids, key)) == -1) { /* key not used */ |
219 | if (!(semflg & IPC_CREAT)) |
220 | err = -ENOENT; |
221 | else |
222 | err = newary(key, nsems, semflg); |
223 | } else if (semflg & IPC_CREAT && semflg & IPC_EXCL) { |
224 | err = -EEXIST; |
225 | } else { |
226 | sma = sem_lock(id); |
227 | if(sma==NULL) |
228 | BUG(); |
229 | if (nsems > sma->sem_nsems) |
230 | err = -EINVAL; |
231 | else if (ipcperms(&sma->sem_perm, semflg)) |
232 | err = -EACCES; |
233 | else { |
234 | int semid = sem_buildid(id, sma->sem_perm.seq); |
235 | err = security_sem_associate(sma, semflg); |
236 | if (!err) |
237 | err = semid; |
238 | } |
239 | sem_unlock(sma); |
240 | } |
241 | |
242 | up(&sem_ids.sem); |
243 | return err; |
244 | } |
245 | |
246 | /* Manage the doubly linked list sma->sem_pending as a FIFO: |
247 | * insert new queue elements at the tail sma->sem_pending_last. |
248 | */ |
249 | static inline void append_to_queue (struct sem_array * sma, |
250 | struct sem_queue * q) |
251 | { |
252 | *(q->prev = sma->sem_pending_last) = q; |
253 | *(sma->sem_pending_last = &q->next) = NULL; |
254 | } |
255 | |
256 | static inline void prepend_to_queue (struct sem_array * sma, |
257 | struct sem_queue * q) |
258 | { |
259 | q->next = sma->sem_pending; |
260 | *(q->prev = &sma->sem_pending) = q; |
261 | if (q->next) |
262 | q->next->prev = &q->next; |
263 | else /* sma->sem_pending_last == &sma->sem_pending */ |
264 | sma->sem_pending_last = &q->next; |
265 | } |
266 | |
267 | static inline void remove_from_queue (struct sem_array * sma, |
268 | struct sem_queue * q) |
269 | { |
270 | *(q->prev) = q->next; |
271 | if (q->next) |
272 | q->next->prev = q->prev; |
273 | else /* sma->sem_pending_last == &q->next */ |
274 | sma->sem_pending_last = q->prev; |
275 | q->prev = NULL; /* mark as removed */ |
276 | } |
277 | |
278 | /* |
279 | * Determine whether a sequence of semaphore operations would succeed |
280 | * all at once. Return 0 if yes, 1 if need to sleep, else return error code. |
281 | */ |
282 | |
283 | static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops, |
284 | int nsops, struct sem_undo *un, int pid) |
285 | { |
286 | int result, sem_op; |
287 | struct sembuf *sop; |
288 | struct sem * curr; |
289 | |
290 | for (sop = sops; sop < sops + nsops; sop++) { |
291 | curr = sma->sem_base + sop->sem_num; |
292 | sem_op = sop->sem_op; |
293 | result = curr->semval; |
294 | |
295 | if (!sem_op && result) |
296 | goto would_block; |
297 | |
298 | result += sem_op; |
299 | if (result < 0) |
300 | goto would_block; |
301 | if (result > SEMVMX) |
302 | goto out_of_range; |
303 | if (sop->sem_flg & SEM_UNDO) { |
304 | int undo = un->semadj[sop->sem_num] - sem_op; |
305 | /* |
306 | * Exceeding the undo range is an error. |
307 | */ |
308 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) |
309 | goto out_of_range; |
310 | } |
311 | curr->semval = result; |
312 | } |
313 | |
314 | sop--; |
315 | while (sop >= sops) { |
316 | sma->sem_base[sop->sem_num].sempid = pid; |
317 | if (sop->sem_flg & SEM_UNDO) |
318 | un->semadj[sop->sem_num] -= sop->sem_op; |
319 | sop--; |
320 | } |
321 | |
322 | sma->sem_otime = get_seconds(); |
323 | return 0; |
324 | |
325 | out_of_range: |
326 | result = -ERANGE; |
327 | goto undo; |
328 | |
329 | would_block: |
330 | if (sop->sem_flg & IPC_NOWAIT) |
331 | result = -EAGAIN; |
332 | else |
333 | result = 1; |
334 | |
335 | undo: |
336 | sop--; |
337 | while (sop >= sops) { |
338 | sma->sem_base[sop->sem_num].semval -= sop->sem_op; |
339 | sop--; |
340 | } |
341 | |
342 | return result; |
343 | } |
344 | |
345 | /* Go through the pending queue for the indicated semaphore |
346 | * looking for tasks that can be completed. |
347 | */ |
348 | static void update_queue (struct sem_array * sma) |
349 | { |
350 | int error; |
351 | struct sem_queue * q; |
352 | |
353 | q = sma->sem_pending; |
354 | while(q) { |
355 | error = try_atomic_semop(sma, q->sops, q->nsops, |
356 | q->undo, q->pid); |
357 | |
358 | /* Does q->sleeper still need to sleep? */ |
359 | if (error <= 0) { |
360 | struct sem_queue *n; |
361 | remove_from_queue(sma,q); |
362 | q->status = IN_WAKEUP; |
363 | /* |
364 | * Continue scanning. The next operation |
365 | * that must be checked depends on the type of the |
366 | * completed operation: |
367 | * - if the operation modified the array, then |
368 | * restart from the head of the queue and |
369 | * check for threads that might be waiting |
370 | * for semaphore values to become 0. |
371 | * - if the operation didn't modify the array, |
372 | * then just continue. |
373 | */ |
374 | if (q->alter) |
375 | n = sma->sem_pending; |
376 | else |
377 | n = q->next; |
378 | wake_up_process(q->sleeper); |
379 | /* hands-off: q will disappear immediately after |
380 | * writing q->status. |
381 | */ |
382 | q->status = error; |
383 | q = n; |
384 | } else { |
385 | q = q->next; |
386 | } |
387 | } |
388 | } |
389 | |
390 | /* The following counts are associated to each semaphore: |
391 | * semncnt number of tasks waiting on semval being nonzero |
392 | * semzcnt number of tasks waiting on semval being zero |
393 | * This model assumes that a task waits on exactly one semaphore. |
394 | * Since semaphore operations are to be performed atomically, tasks actually |
395 | * wait on a whole sequence of semaphores simultaneously. |
396 | * The counts we return here are a rough approximation, but still |
397 | * warrant that semncnt+semzcnt>0 if the task is on the pending queue. |
398 | */ |
399 | static int count_semncnt (struct sem_array * sma, ushort semnum) |
400 | { |
401 | int semncnt; |
402 | struct sem_queue * q; |
403 | |
404 | semncnt = 0; |
405 | for (q = sma->sem_pending; q; q = q->next) { |
406 | struct sembuf * sops = q->sops; |
407 | int nsops = q->nsops; |
408 | int i; |
409 | for (i = 0; i < nsops; i++) |
410 | if (sops[i].sem_num == semnum |
411 | && (sops[i].sem_op < 0) |
412 | && !(sops[i].sem_flg & IPC_NOWAIT)) |
413 | semncnt++; |
414 | } |
415 | return semncnt; |
416 | } |
417 | static int count_semzcnt (struct sem_array * sma, ushort semnum) |
418 | { |
419 | int semzcnt; |
420 | struct sem_queue * q; |
421 | |
422 | semzcnt = 0; |
423 | for (q = sma->sem_pending; q; q = q->next) { |
424 | struct sembuf * sops = q->sops; |
425 | int nsops = q->nsops; |
426 | int i; |
427 | for (i = 0; i < nsops; i++) |
428 | if (sops[i].sem_num == semnum |
429 | && (sops[i].sem_op == 0) |
430 | && !(sops[i].sem_flg & IPC_NOWAIT)) |
431 | semzcnt++; |
432 | } |
433 | return semzcnt; |
434 | } |
435 | |
436 | /* Free a semaphore set. freeary() is called with sem_ids.sem down and |
437 | * the spinlock for this semaphore set hold. sem_ids.sem remains locked |
438 | * on exit. |
439 | */ |
440 | static void freeary (struct sem_array *sma, int id) |
441 | { |
442 | struct sem_undo *un; |
443 | struct sem_queue *q; |
444 | int size; |
445 | |
446 | /* Invalidate the existing undo structures for this semaphore set. |
447 | * (They will be freed without any further action in exit_sem() |
448 | * or during the next semop.) |
449 | */ |
450 | for (un = sma->undo; un; un = un->id_next) |
451 | un->semid = -1; |
452 | |
453 | /* Wake up all pending processes and let them fail with EIDRM. */ |
454 | q = sma->sem_pending; |
455 | while(q) { |
456 | struct sem_queue *n; |
457 | /* lazy remove_from_queue: we are killing the whole queue */ |
458 | q->prev = NULL; |
459 | n = q->next; |
460 | q->status = IN_WAKEUP; |
461 | wake_up_process(q->sleeper); /* doesn't sleep */ |
462 | q->status = -EIDRM; /* hands-off q */ |
463 | q = n; |
464 | } |
465 | |
466 | /* Remove the semaphore set from the ID array*/ |
467 | sma = sem_rmid(id); |
468 | sem_unlock(sma); |
469 | |
470 | used_sems -= sma->sem_nsems; |
471 | size = sizeof (*sma) + sma->sem_nsems * sizeof (struct sem); |
472 | security_sem_free(sma); |
473 | ipc_rcu_putref(sma); |
474 | } |
475 | |
476 | static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) |
477 | { |
478 | switch(version) { |
479 | case IPC_64: |
480 | return copy_to_user(buf, in, sizeof(*in)); |
481 | case IPC_OLD: |
482 | { |
483 | struct semid_ds out; |
484 | |
485 | ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm); |
486 | |
487 | out.sem_otime = in->sem_otime; |
488 | out.sem_ctime = in->sem_ctime; |
489 | out.sem_nsems = in->sem_nsems; |
490 | |
491 | return copy_to_user(buf, &out, sizeof(out)); |
492 | } |
493 | default: |
494 | return -EINVAL; |
495 | } |
496 | } |
497 | |
498 | static int semctl_nolock(int semid, int semnum, int cmd, int version, union semun arg) |
499 | { |
500 | int err = -EINVAL; |
501 | struct sem_array *sma; |
502 | |
503 | switch(cmd) { |
504 | case IPC_INFO: |
505 | case SEM_INFO: |
506 | { |
507 | struct seminfo seminfo; |
508 | int max_id; |
509 | |
510 | err = security_sem_semctl(NULL, cmd); |
511 | if (err) |
512 | return err; |
513 | |
514 | memset(&seminfo,0,sizeof(seminfo)); |
515 | seminfo.semmni = sc_semmni; |
516 | seminfo.semmns = sc_semmns; |
517 | seminfo.semmsl = sc_semmsl; |
518 | seminfo.semopm = sc_semopm; |
519 | seminfo.semvmx = SEMVMX; |
520 | seminfo.semmnu = SEMMNU; |
521 | seminfo.semmap = SEMMAP; |
522 | seminfo.semume = SEMUME; |
523 | down(&sem_ids.sem); |
524 | if (cmd == SEM_INFO) { |
525 | seminfo.semusz = sem_ids.in_use; |
526 | seminfo.semaem = used_sems; |
527 | } else { |
528 | seminfo.semusz = SEMUSZ; |
529 | seminfo.semaem = SEMAEM; |
530 | } |
531 | max_id = sem_ids.max_id; |
532 | up(&sem_ids.sem); |
533 | if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) |
534 | return -EFAULT; |
535 | return (max_id < 0) ? 0: max_id; |
536 | } |
537 | case SEM_STAT: |
538 | { |
539 | struct semid64_ds tbuf; |
540 | int id; |
541 | |
542 | if(semid >= sem_ids.entries->size) |
543 | return -EINVAL; |
544 | |
545 | memset(&tbuf,0,sizeof(tbuf)); |
546 | |
547 | sma = sem_lock(semid); |
548 | if(sma == NULL) |
549 | return -EINVAL; |
550 | |
551 | err = -EACCES; |
552 | if (ipcperms (&sma->sem_perm, S_IRUGO)) |
553 | goto out_unlock; |
554 | |
555 | err = security_sem_semctl(sma, cmd); |
556 | if (err) |
557 | goto out_unlock; |
558 | |
559 | id = sem_buildid(semid, sma->sem_perm.seq); |
560 | |
561 | kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); |
562 | tbuf.sem_otime = sma->sem_otime; |
563 | tbuf.sem_ctime = sma->sem_ctime; |
564 | tbuf.sem_nsems = sma->sem_nsems; |
565 | sem_unlock(sma); |
566 | if (copy_semid_to_user (arg.buf, &tbuf, version)) |
567 | return -EFAULT; |
568 | return id; |
569 | } |
570 | default: |
571 | return -EINVAL; |
572 | } |
573 | return err; |
574 | out_unlock: |
575 | sem_unlock(sma); |
576 | return err; |
577 | } |
578 | |
579 | static int semctl_main(int semid, int semnum, int cmd, int version, union semun arg) |
580 | { |
581 | struct sem_array *sma; |
582 | struct sem* curr; |
583 | int err; |
584 | ushort fast_sem_io[SEMMSL_FAST]; |
585 | ushort* sem_io = fast_sem_io; |
586 | int nsems; |
587 | |
588 | sma = sem_lock(semid); |
589 | if(sma==NULL) |
590 | return -EINVAL; |
591 | |
592 | nsems = sma->sem_nsems; |
593 | |
594 | err=-EIDRM; |
595 | if (sem_checkid(sma,semid)) |
596 | goto out_unlock; |
597 | |
598 | err = -EACCES; |
599 | if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO)) |
600 | goto out_unlock; |
601 | |
602 | err = security_sem_semctl(sma, cmd); |
603 | if (err) |
604 | goto out_unlock; |
605 | |
606 | err = -EACCES; |
607 | switch (cmd) { |
608 | case GETALL: |
609 | { |
610 | ushort __user *array = arg.array; |
611 | int i; |
612 | |
613 | if(nsems > SEMMSL_FAST) { |
614 | ipc_rcu_getref(sma); |
615 | sem_unlock(sma); |
616 | |
617 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
618 | if(sem_io == NULL) { |
619 | ipc_lock_by_ptr(&sma->sem_perm); |
620 | ipc_rcu_putref(sma); |
621 | sem_unlock(sma); |
622 | return -ENOMEM; |
623 | } |
624 | |
625 | ipc_lock_by_ptr(&sma->sem_perm); |
626 | ipc_rcu_putref(sma); |
627 | if (sma->sem_perm.deleted) { |
628 | sem_unlock(sma); |
629 | err = -EIDRM; |
630 | goto out_free; |
631 | } |
632 | } |
633 | |
634 | for (i = 0; i < sma->sem_nsems; i++) |
635 | sem_io[i] = sma->sem_base[i].semval; |
636 | sem_unlock(sma); |
637 | err = 0; |
638 | if(copy_to_user(array, sem_io, nsems*sizeof(ushort))) |
639 | err = -EFAULT; |
640 | goto out_free; |
641 | } |
642 | case SETALL: |
643 | { |
644 | int i; |
645 | struct sem_undo *un; |
646 | |
647 | ipc_rcu_getref(sma); |
648 | sem_unlock(sma); |
649 | |
650 | if(nsems > SEMMSL_FAST) { |
651 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
652 | if(sem_io == NULL) { |
653 | ipc_lock_by_ptr(&sma->sem_perm); |
654 | ipc_rcu_putref(sma); |
655 | sem_unlock(sma); |
656 | return -ENOMEM; |
657 | } |
658 | } |
659 | |
660 | if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) { |
661 | ipc_lock_by_ptr(&sma->sem_perm); |
662 | ipc_rcu_putref(sma); |
663 | sem_unlock(sma); |
664 | err = -EFAULT; |
665 | goto out_free; |
666 | } |
667 | |
668 | for (i = 0; i < nsems; i++) { |
669 | if (sem_io[i] > SEMVMX) { |
670 | ipc_lock_by_ptr(&sma->sem_perm); |
671 | ipc_rcu_putref(sma); |
672 | sem_unlock(sma); |
673 | err = -ERANGE; |
674 | goto out_free; |
675 | } |
676 | } |
677 | ipc_lock_by_ptr(&sma->sem_perm); |
678 | ipc_rcu_putref(sma); |
679 | if (sma->sem_perm.deleted) { |
680 | sem_unlock(sma); |
681 | err = -EIDRM; |
682 | goto out_free; |
683 | } |
684 | |
685 | for (i = 0; i < nsems; i++) |
686 | sma->sem_base[i].semval = sem_io[i]; |
687 | for (un = sma->undo; un; un = un->id_next) |
688 | for (i = 0; i < nsems; i++) |
689 | un->semadj[i] = 0; |
690 | sma->sem_ctime = get_seconds(); |
691 | /* maybe some queued-up processes were waiting for this */ |
692 | update_queue(sma); |
693 | err = 0; |
694 | goto out_unlock; |
695 | } |
696 | case IPC_STAT: |
697 | { |
698 | struct semid64_ds tbuf; |
699 | memset(&tbuf,0,sizeof(tbuf)); |
700 | kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); |
701 | tbuf.sem_otime = sma->sem_otime; |
702 | tbuf.sem_ctime = sma->sem_ctime; |
703 | tbuf.sem_nsems = sma->sem_nsems; |
704 | sem_unlock(sma); |
705 | if (copy_semid_to_user (arg.buf, &tbuf, version)) |
706 | return -EFAULT; |
707 | return 0; |
708 | } |
709 | /* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */ |
710 | } |
711 | err = -EINVAL; |
712 | if(semnum < 0 || semnum >= nsems) |
713 | goto out_unlock; |
714 | |
715 | curr = &sma->sem_base[semnum]; |
716 | |
717 | switch (cmd) { |
718 | case GETVAL: |
719 | err = curr->semval; |
720 | goto out_unlock; |
721 | case GETPID: |
722 | err = curr->sempid; |
723 | goto out_unlock; |
724 | case GETNCNT: |
725 | err = count_semncnt(sma,semnum); |
726 | goto out_unlock; |
727 | case GETZCNT: |
728 | err = count_semzcnt(sma,semnum); |
729 | goto out_unlock; |
730 | case SETVAL: |
731 | { |
732 | int val = arg.val; |
733 | struct sem_undo *un; |
734 | err = -ERANGE; |
735 | if (val > SEMVMX || val < 0) |
736 | goto out_unlock; |
737 | |
738 | for (un = sma->undo; un; un = un->id_next) |
739 | un->semadj[semnum] = 0; |
740 | curr->semval = val; |
741 | curr->sempid = current->tgid; |
742 | sma->sem_ctime = get_seconds(); |
743 | /* maybe some queued-up processes were waiting for this */ |
744 | update_queue(sma); |
745 | err = 0; |
746 | goto out_unlock; |
747 | } |
748 | } |
749 | out_unlock: |
750 | sem_unlock(sma); |
751 | out_free: |
752 | if(sem_io != fast_sem_io) |
753 | ipc_free(sem_io, sizeof(ushort)*nsems); |
754 | return err; |
755 | } |
756 | |
757 | struct sem_setbuf { |
758 | uid_t uid; |
759 | gid_t gid; |
760 | mode_t mode; |
761 | }; |
762 | |
763 | static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version) |
764 | { |
765 | switch(version) { |
766 | case IPC_64: |
767 | { |
768 | struct semid64_ds tbuf; |
769 | |
770 | if(copy_from_user(&tbuf, buf, sizeof(tbuf))) |
771 | return -EFAULT; |
772 | |
773 | out->uid = tbuf.sem_perm.uid; |
774 | out->gid = tbuf.sem_perm.gid; |
775 | out->mode = tbuf.sem_perm.mode; |
776 | |
777 | return 0; |
778 | } |
779 | case IPC_OLD: |
780 | { |
781 | struct semid_ds tbuf_old; |
782 | |
783 | if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
784 | return -EFAULT; |
785 | |
786 | out->uid = tbuf_old.sem_perm.uid; |
787 | out->gid = tbuf_old.sem_perm.gid; |
788 | out->mode = tbuf_old.sem_perm.mode; |
789 | |
790 | return 0; |
791 | } |
792 | default: |
793 | return -EINVAL; |
794 | } |
795 | } |
796 | |
797 | static int semctl_down(int semid, int semnum, int cmd, int version, union semun arg) |
798 | { |
799 | struct sem_array *sma; |
800 | int err; |
801 | struct sem_setbuf setbuf; |
802 | struct kern_ipc_perm *ipcp; |
803 | |
804 | if(cmd == IPC_SET) { |
805 | if(copy_semid_from_user (&setbuf, arg.buf, version)) |
806 | return -EFAULT; |
807 | if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode))) |
808 | return err; |
809 | } |
810 | sma = sem_lock(semid); |
811 | if(sma==NULL) |
812 | return -EINVAL; |
813 | |
814 | if (sem_checkid(sma,semid)) { |
815 | err=-EIDRM; |
816 | goto out_unlock; |
817 | } |
818 | ipcp = &sma->sem_perm; |
819 | |
820 | if (current->euid != ipcp->cuid && |
821 | current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) { |
822 | err=-EPERM; |
823 | goto out_unlock; |
824 | } |
825 | |
826 | err = security_sem_semctl(sma, cmd); |
827 | if (err) |
828 | goto out_unlock; |
829 | |
830 | switch(cmd){ |
831 | case IPC_RMID: |
832 | freeary(sma, semid); |
833 | err = 0; |
834 | break; |
835 | case IPC_SET: |
836 | ipcp->uid = setbuf.uid; |
837 | ipcp->gid = setbuf.gid; |
838 | ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
839 | | (setbuf.mode & S_IRWXUGO); |
840 | sma->sem_ctime = get_seconds(); |
841 | sem_unlock(sma); |
842 | err = 0; |
843 | break; |
844 | default: |
845 | sem_unlock(sma); |
846 | err = -EINVAL; |
847 | break; |
848 | } |
849 | return err; |
850 | |
851 | out_unlock: |
852 | sem_unlock(sma); |
853 | return err; |
854 | } |
855 | |
856 | asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg) |
857 | { |
858 | int err = -EINVAL; |
859 | int version; |
860 | |
861 | if (semid < 0) |
862 | return -EINVAL; |
863 | |
864 | version = ipc_parse_version(&cmd); |
865 | |
866 | switch(cmd) { |
867 | case IPC_INFO: |
868 | case SEM_INFO: |
869 | case SEM_STAT: |
870 | err = semctl_nolock(semid,semnum,cmd,version,arg); |
871 | return err; |
872 | case GETALL: |
873 | case GETVAL: |
874 | case GETPID: |
875 | case GETNCNT: |
876 | case GETZCNT: |
877 | case IPC_STAT: |
878 | case SETVAL: |
879 | case SETALL: |
880 | err = semctl_main(semid,semnum,cmd,version,arg); |
881 | return err; |
882 | case IPC_RMID: |
883 | case IPC_SET: |
884 | down(&sem_ids.sem); |
885 | err = semctl_down(semid,semnum,cmd,version,arg); |
886 | up(&sem_ids.sem); |
887 | return err; |
888 | default: |
889 | return -EINVAL; |
890 | } |
891 | } |
892 | |
893 | static inline void lock_semundo(void) |
894 | { |
895 | struct sem_undo_list *undo_list; |
896 | |
897 | undo_list = current->sysvsem.undo_list; |
898 | if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1)) |
899 | spin_lock(&undo_list->lock); |
900 | } |
901 | |
902 | /* This code has an interaction with copy_semundo(). |
903 | * Consider; two tasks are sharing the undo_list. task1 |
904 | * acquires the undo_list lock in lock_semundo(). If task2 now |
905 | * exits before task1 releases the lock (by calling |
906 | * unlock_semundo()), then task1 will never call spin_unlock(). |
907 | * This leave the sem_undo_list in a locked state. If task1 now creats task3 |
908 | * and once again shares the sem_undo_list, the sem_undo_list will still be |
909 | * locked, and future SEM_UNDO operations will deadlock. This case is |
910 | * dealt with in copy_semundo() by having it reinitialize the spin lock when |
911 | * the refcnt goes from 1 to 2. |
912 | */ |
913 | static inline void unlock_semundo(void) |
914 | { |
915 | struct sem_undo_list *undo_list; |
916 | |
917 | undo_list = current->sysvsem.undo_list; |
918 | if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1)) |
919 | spin_unlock(&undo_list->lock); |
920 | } |
921 | |
922 | |
923 | /* If the task doesn't already have a undo_list, then allocate one |
924 | * here. We guarantee there is only one thread using this undo list, |
925 | * and current is THE ONE |
926 | * |
927 | * If this allocation and assignment succeeds, but later |
928 | * portions of this code fail, there is no need to free the sem_undo_list. |
929 | * Just let it stay associated with the task, and it'll be freed later |
930 | * at exit time. |
931 | * |
932 | * This can block, so callers must hold no locks. |
933 | */ |
934 | static inline int get_undo_list(struct sem_undo_list **undo_listp) |
935 | { |
936 | struct sem_undo_list *undo_list; |
937 | int size; |
938 | |
939 | undo_list = current->sysvsem.undo_list; |
940 | if (!undo_list) { |
941 | size = sizeof(struct sem_undo_list); |
942 | undo_list = (struct sem_undo_list *) kmalloc(size, GFP_KERNEL); |
943 | if (undo_list == NULL) |
944 | return -ENOMEM; |
945 | memset(undo_list, 0, size); |
946 | /* don't initialize unodhd->lock here. It's done |
947 | * in copy_semundo() instead. |
948 | */ |
949 | atomic_set(&undo_list->refcnt, 1); |
950 | current->sysvsem.undo_list = undo_list; |
951 | } |
952 | *undo_listp = undo_list; |
953 | return 0; |
954 | } |
955 | |
956 | static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) |
957 | { |
958 | struct sem_undo **last, *un; |
959 | |
960 | last = &ulp->proc_list; |
961 | un = *last; |
962 | while(un != NULL) { |
963 | if(un->semid==semid) |
964 | break; |
965 | if(un->semid==-1) { |
966 | *last=un->proc_next; |
967 | kfree(un); |
968 | } else { |
969 | last=&un->proc_next; |
970 | } |
971 | un=*last; |
972 | } |
973 | return un; |
974 | } |
975 | |
976 | static struct sem_undo *find_undo(int semid) |
977 | { |
978 | struct sem_array *sma; |
979 | struct sem_undo_list *ulp; |
980 | struct sem_undo *un, *new; |
981 | int nsems; |
982 | int error; |
983 | |
984 | error = get_undo_list(&ulp); |
985 | if (error) |
986 | return ERR_PTR(error); |
987 | |
988 | lock_semundo(); |
989 | un = lookup_undo(ulp, semid); |
990 | unlock_semundo(); |
991 | if (likely(un!=NULL)) |
992 | goto out; |
993 | |
994 | /* no undo structure around - allocate one. */ |
995 | sma = sem_lock(semid); |
996 | un = ERR_PTR(-EINVAL); |
997 | if(sma==NULL) |
998 | goto out; |
999 | un = ERR_PTR(-EIDRM); |
1000 | if (sem_checkid(sma,semid)) { |
1001 | sem_unlock(sma); |
1002 | goto out; |
1003 | } |
1004 | nsems = sma->sem_nsems; |
1005 | ipc_rcu_getref(sma); |
1006 | sem_unlock(sma); |
1007 | |
1008 | new = (struct sem_undo *) kmalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); |
1009 | if (!new) { |
1010 | ipc_lock_by_ptr(&sma->sem_perm); |
1011 | ipc_rcu_putref(sma); |
1012 | sem_unlock(sma); |
1013 | return ERR_PTR(-ENOMEM); |
1014 | } |
1015 | memset(new, 0, sizeof(struct sem_undo) + sizeof(short)*nsems); |
1016 | new->semadj = (short *) &new[1]; |
1017 | new->semid = semid; |
1018 | |
1019 | lock_semundo(); |
1020 | un = lookup_undo(ulp, semid); |
1021 | if (un) { |
1022 | unlock_semundo(); |
1023 | kfree(new); |
1024 | ipc_lock_by_ptr(&sma->sem_perm); |
1025 | ipc_rcu_putref(sma); |
1026 | sem_unlock(sma); |
1027 | goto out; |
1028 | } |
1029 | ipc_lock_by_ptr(&sma->sem_perm); |
1030 | ipc_rcu_putref(sma); |
1031 | if (sma->sem_perm.deleted) { |
1032 | sem_unlock(sma); |
1033 | unlock_semundo(); |
1034 | kfree(new); |
1035 | un = ERR_PTR(-EIDRM); |
1036 | goto out; |
1037 | } |
1038 | new->proc_next = ulp->proc_list; |
1039 | ulp->proc_list = new; |
1040 | new->id_next = sma->undo; |
1041 | sma->undo = new; |
1042 | sem_unlock(sma); |
1043 | un = new; |
1044 | unlock_semundo(); |
1045 | out: |
1046 | return un; |
1047 | } |
1048 | |
1049 | asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops, |
1050 | unsigned nsops, const struct timespec __user *timeout) |
1051 | { |
1052 | int error = -EINVAL; |
1053 | struct sem_array *sma; |
1054 | struct sembuf fast_sops[SEMOPM_FAST]; |
1055 | struct sembuf* sops = fast_sops, *sop; |
1056 | struct sem_undo *un; |
1057 | int undos = 0, decrease = 0, alter = 0, max; |
1058 | struct sem_queue queue; |
1059 | unsigned long jiffies_left = 0; |
1060 | |
1061 | if (nsops < 1 || semid < 0) |
1062 | return -EINVAL; |
1063 | if (nsops > sc_semopm) |
1064 | return -E2BIG; |
1065 | if(nsops > SEMOPM_FAST) { |
1066 | sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL); |
1067 | if(sops==NULL) |
1068 | return -ENOMEM; |
1069 | } |
1070 | if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) { |
1071 | error=-EFAULT; |
1072 | goto out_free; |
1073 | } |
1074 | if (timeout) { |
1075 | struct timespec _timeout; |
1076 | if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { |
1077 | error = -EFAULT; |
1078 | goto out_free; |
1079 | } |
1080 | if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || |
1081 | _timeout.tv_nsec >= 1000000000L) { |
1082 | error = -EINVAL; |
1083 | goto out_free; |
1084 | } |
1085 | jiffies_left = timespec_to_jiffies(&_timeout); |
1086 | } |
1087 | max = 0; |
1088 | for (sop = sops; sop < sops + nsops; sop++) { |
1089 | if (sop->sem_num >= max) |
1090 | max = sop->sem_num; |
1091 | if (sop->sem_flg & SEM_UNDO) |
1092 | undos++; |
1093 | if (sop->sem_op < 0) |
1094 | decrease = 1; |
1095 | if (sop->sem_op > 0) |
1096 | alter = 1; |
1097 | } |
1098 | alter |= decrease; |
1099 | |
1100 | retry_undos: |
1101 | if (undos) { |
1102 | un = find_undo(semid); |
1103 | if (IS_ERR(un)) { |
1104 | error = PTR_ERR(un); |
1105 | goto out_free; |
1106 | } |
1107 | } else |
1108 | un = NULL; |
1109 | |
1110 | sma = sem_lock(semid); |
1111 | error=-EINVAL; |
1112 | if(sma==NULL) |
1113 | goto out_free; |
1114 | error = -EIDRM; |
1115 | if (sem_checkid(sma,semid)) |
1116 | goto out_unlock_free; |
1117 | /* |
1118 | * semid identifies are not unique - find_undo may have |
1119 | * allocated an undo structure, it was invalidated by an RMID |
1120 | * and now a new array with received the same id. Check and retry. |
1121 | */ |
1122 | if (un && un->semid == -1) { |
1123 | sem_unlock(sma); |
1124 | goto retry_undos; |
1125 | } |
1126 | error = -EFBIG; |
1127 | if (max >= sma->sem_nsems) |
1128 | goto out_unlock_free; |
1129 | |
1130 | error = -EACCES; |
1131 | if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) |
1132 | goto out_unlock_free; |
1133 | |
1134 | error = security_sem_semop(sma, sops, nsops, alter); |
1135 | if (error) |
1136 | goto out_unlock_free; |
1137 | |
1138 | error = try_atomic_semop (sma, sops, nsops, un, current->tgid); |
1139 | if (error <= 0) { |
1140 | if (alter && error == 0) |
1141 | update_queue (sma); |
1142 | goto out_unlock_free; |
1143 | } |
1144 | |
1145 | /* We need to sleep on this operation, so we put the current |
1146 | * task into the pending queue and go to sleep. |
1147 | */ |
1148 | |
1149 | queue.sma = sma; |
1150 | queue.sops = sops; |
1151 | queue.nsops = nsops; |
1152 | queue.undo = un; |
1153 | queue.pid = current->tgid; |
1154 | queue.id = semid; |
1155 | queue.alter = alter; |
1156 | if (alter) |
1157 | append_to_queue(sma ,&queue); |
1158 | else |
1159 | prepend_to_queue(sma ,&queue); |
1160 | |
1161 | queue.status = -EINTR; |
1162 | queue.sleeper = current; |
1163 | current->state = TASK_INTERRUPTIBLE; |
1164 | sem_unlock(sma); |
1165 | |
1166 | if (timeout) |
1167 | jiffies_left = schedule_timeout(jiffies_left); |
1168 | else |
1169 | schedule(); |
1170 | |
1171 | error = queue.status; |
1172 | while(unlikely(error == IN_WAKEUP)) { |
1173 | cpu_relax(); |
1174 | error = queue.status; |
1175 | } |
1176 | |
1177 | if (error != -EINTR) { |
1178 | /* fast path: update_queue already obtained all requested |
1179 | * resources */ |
1180 | goto out_free; |
1181 | } |
1182 | |
1183 | sma = sem_lock(semid); |
1184 | if(sma==NULL) { |
1185 | if(queue.prev != NULL) |
1186 | BUG(); |
1187 | error = -EIDRM; |
1188 | goto out_free; |
1189 | } |
1190 | |
1191 | /* |
1192 | * If queue.status != -EINTR we are woken up by another process |
1193 | */ |
1194 | error = queue.status; |
1195 | if (error != -EINTR) { |
1196 | goto out_unlock_free; |
1197 | } |
1198 | |
1199 | /* |
1200 | * If an interrupt occurred we have to clean up the queue |
1201 | */ |
1202 | if (timeout && jiffies_left == 0) |
1203 | error = -EAGAIN; |
1204 | remove_from_queue(sma,&queue); |
1205 | goto out_unlock_free; |
1206 | |
1207 | out_unlock_free: |
1208 | sem_unlock(sma); |
1209 | out_free: |
1210 | if(sops != fast_sops) |
1211 | kfree(sops); |
1212 | return error; |
1213 | } |
1214 | |
1215 | asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsops) |
1216 | { |
1217 | return sys_semtimedop(semid, tsops, nsops, NULL); |
1218 | } |
1219 | |
1220 | /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between |
1221 | * parent and child tasks. |
1222 | * |
1223 | * See the notes above unlock_semundo() regarding the spin_lock_init() |
1224 | * in this code. Initialize the undo_list->lock here instead of get_undo_list() |
1225 | * because of the reasoning in the comment above unlock_semundo. |
1226 | */ |
1227 | |
1228 | int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) |
1229 | { |
1230 | struct sem_undo_list *undo_list; |
1231 | int error; |
1232 | |
1233 | if (clone_flags & CLONE_SYSVSEM) { |
1234 | error = get_undo_list(&undo_list); |
1235 | if (error) |
1236 | return error; |
1237 | if (atomic_read(&undo_list->refcnt) == 1) |
1238 | spin_lock_init(&undo_list->lock); |
1239 | atomic_inc(&undo_list->refcnt); |
1240 | tsk->sysvsem.undo_list = undo_list; |
1241 | } else |
1242 | tsk->sysvsem.undo_list = NULL; |
1243 | |
1244 | return 0; |
1245 | } |
1246 | |
1247 | /* |
1248 | * add semadj values to semaphores, free undo structures. |
1249 | * undo structures are not freed when semaphore arrays are destroyed |
1250 | * so some of them may be out of date. |
1251 | * IMPLEMENTATION NOTE: There is some confusion over whether the |
1252 | * set of adjustments that needs to be done should be done in an atomic |
1253 | * manner or not. That is, if we are attempting to decrement the semval |
1254 | * should we queue up and wait until we can do so legally? |
1255 | * The original implementation attempted to do this (queue and wait). |
1256 | * The current implementation does not do so. The POSIX standard |
1257 | * and SVID should be consulted to determine what behavior is mandated. |
1258 | */ |
1259 | void exit_sem(struct task_struct *tsk) |
1260 | { |
1261 | struct sem_undo_list *undo_list; |
1262 | struct sem_undo *u, **up; |
1263 | |
1264 | undo_list = tsk->sysvsem.undo_list; |
1265 | if (!undo_list) |
1266 | return; |
1267 | |
1268 | if (!atomic_dec_and_test(&undo_list->refcnt)) |
1269 | return; |
1270 | |
1271 | /* There's no need to hold the semundo list lock, as current |
1272 | * is the last task exiting for this undo list. |
1273 | */ |
1274 | for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) { |
1275 | struct sem_array *sma; |
1276 | int nsems, i; |
1277 | struct sem_undo *un, **unp; |
1278 | int semid; |
1279 | |
1280 | semid = u->semid; |
1281 | |
1282 | if(semid == -1) |
1283 | continue; |
1284 | sma = sem_lock(semid); |
1285 | if (sma == NULL) |
1286 | continue; |
1287 | |
1288 | if (u->semid == -1) |
1289 | goto next_entry; |
1290 | |
1291 | BUG_ON(sem_checkid(sma,u->semid)); |
1292 | |
1293 | /* remove u from the sma->undo list */ |
1294 | for (unp = &sma->undo; (un = *unp); unp = &un->id_next) { |
1295 | if (u == un) |
1296 | goto found; |
1297 | } |
1298 | printk ("exit_sem undo list error id=%d\n", u->semid); |
1299 | goto next_entry; |
1300 | found: |
1301 | *unp = un->id_next; |
1302 | /* perform adjustments registered in u */ |
1303 | nsems = sma->sem_nsems; |
1304 | for (i = 0; i < nsems; i++) { |
1305 | struct sem * sem = &sma->sem_base[i]; |
1306 | if (u->semadj[i]) { |
1307 | sem->semval += u->semadj[i]; |
1308 | /* |
1309 | * Range checks of the new semaphore value, |
1310 | * not defined by sus: |
1311 | * - Some unices ignore the undo entirely |
1312 | * (e.g. HP UX 11i 11.22, Tru64 V5.1) |
1313 | * - some cap the value (e.g. FreeBSD caps |
1314 | * at 0, but doesn't enforce SEMVMX) |
1315 | * |
1316 | * Linux caps the semaphore value, both at 0 |
1317 | * and at SEMVMX. |
1318 | * |
1319 | * Manfred <manfred@colorfullife.com> |
1320 | */ |
1321 | if (sem->semval < 0) |
1322 | sem->semval = 0; |
1323 | if (sem->semval > SEMVMX) |
1324 | sem->semval = SEMVMX; |
1325 | sem->sempid = current->tgid; |
1326 | } |
1327 | } |
1328 | sma->sem_otime = get_seconds(); |
1329 | /* maybe some queued-up processes were waiting for this */ |
1330 | update_queue(sma); |
1331 | next_entry: |
1332 | sem_unlock(sma); |
1333 | } |
1334 | kfree(undo_list); |
1335 | } |
1336 | |
1337 | #ifdef CONFIG_PROC_FS |
1338 | static int sysvipc_sem_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data) |
1339 | { |
1340 | off_t pos = 0; |
1341 | off_t begin = 0; |
1342 | int i, len = 0; |
1343 | |
1344 | len += sprintf(buffer, " key semid perms nsems uid gid cuid cgid otime ctime\n"); |
1345 | down(&sem_ids.sem); |
1346 | |
1347 | for(i = 0; i <= sem_ids.max_id; i++) { |
1348 | struct sem_array *sma; |
1349 | sma = sem_lock(i); |
1350 | if(sma) { |
1351 | len += sprintf(buffer + len, "%10d %10d %4o %10lu %5u %5u %5u %5u %10lu %10lu\n", |
1352 | sma->sem_perm.key, |
1353 | sem_buildid(i,sma->sem_perm.seq), |
1354 | sma->sem_perm.mode, |
1355 | sma->sem_nsems, |
1356 | sma->sem_perm.uid, |
1357 | sma->sem_perm.gid, |
1358 | sma->sem_perm.cuid, |
1359 | sma->sem_perm.cgid, |
1360 | sma->sem_otime, |
1361 | sma->sem_ctime); |
1362 | sem_unlock(sma); |
1363 | |
1364 | pos += len; |
1365 | if(pos < offset) { |
1366 | len = 0; |
1367 | begin = pos; |
1368 | } |
1369 | if(pos > offset + length) |
1370 | goto done; |
1371 | } |
1372 | } |
1373 | *eof = 1; |
1374 | done: |
1375 | up(&sem_ids.sem); |
1376 | *start = buffer + (offset - begin); |
1377 | len -= (offset - begin); |
1378 | if(len > length) |
1379 | len = length; |
1380 | if(len < 0) |
1381 | len = 0; |
1382 | return len; |
1383 | } |
1384 | #endif |