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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Christian Kujau624dffc2006-01-15 02:43:54 +010059 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 * 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>
Steve Grubb073115d2006-04-02 17:07:33 -040064 *
65 * support for audit of ipc object properties and permission changes
66 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
Kirill Korotaeve3893532006-10-02 02:18:22 -070067 *
68 * namespaces support
69 * OpenVZ, SWsoft Inc.
70 * Pavel Emelianov <xemul@openvz.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 */
72
Linus Torvalds1da177e2005-04-16 15:20:36 -070073#include <linux/slab.h>
74#include <linux/spinlock.h>
75#include <linux/init.h>
76#include <linux/proc_fs.h>
77#include <linux/time.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070078#include <linux/security.h>
79#include <linux/syscalls.h>
80#include <linux/audit.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080081#include <linux/capability.h>
Mike Waychison19b49462005-09-06 15:17:10 -070082#include <linux/seq_file.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080083#include <linux/mutex.h>
Kirill Korotaeve3893532006-10-02 02:18:22 -070084#include <linux/nsproxy.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080085
Linus Torvalds1da177e2005-04-16 15:20:36 -070086#include <asm/uaccess.h>
87#include "util.h"
88
Kirill Korotaeve3893532006-10-02 02:18:22 -070089#define sem_ids(ns) (*((ns)->ids[IPC_SEM_IDS]))
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Kirill Korotaeve3893532006-10-02 02:18:22 -070091#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
Kirill Korotaeve3893532006-10-02 02:18:22 -070092#define sem_checkid(ns, sma, semid) \
93 ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
94#define sem_buildid(ns, id, seq) \
95 ipc_buildid(&sem_ids(ns), id, seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
Kirill Korotaeve3893532006-10-02 02:18:22 -070097static struct ipc_ids init_sem_ids;
98
Nadia Derbey7748dbf2007-10-18 23:40:49 -070099static int newary(struct ipc_namespace *, struct ipc_params *);
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700100static void freeary(struct ipc_namespace *, struct sem_array *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700102static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103#endif
104
105#define SEMMSL_FAST 256 /* 512 bytes on stack */
106#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
107
108/*
109 * linked list protection:
110 * sem_undo.id_next,
111 * sem_array.sem_pending{,last},
112 * sem_array.sem_undo: sem_lock() for read/write
113 * sem_undo.proc_next: only "current" is allowed to read/write that field.
114 *
115 */
116
Kirill Korotaeve3893532006-10-02 02:18:22 -0700117#define sc_semmsl sem_ctls[0]
118#define sc_semmns sem_ctls[1]
119#define sc_semopm sem_ctls[2]
120#define sc_semmni sem_ctls[3]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
Cedric Le Goater7d69a1f2007-07-15 23:40:58 -0700122static void __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
Kirill Korotaeve3893532006-10-02 02:18:22 -0700123{
124 ns->ids[IPC_SEM_IDS] = ids;
125 ns->sc_semmsl = SEMMSL;
126 ns->sc_semmns = SEMMNS;
127 ns->sc_semopm = SEMOPM;
128 ns->sc_semmni = SEMMNI;
129 ns->used_sems = 0;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700130 ipc_init_ids(ids);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700131}
132
Kirill Korotaeve3893532006-10-02 02:18:22 -0700133int sem_init_ns(struct ipc_namespace *ns)
134{
135 struct ipc_ids *ids;
136
137 ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
138 if (ids == NULL)
139 return -ENOMEM;
140
141 __sem_init_ns(ns, ids);
142 return 0;
143}
144
145void sem_exit_ns(struct ipc_namespace *ns)
146{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700147 struct sem_array *sma;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700148 int next_id;
149 int total, in_use;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700150
151 mutex_lock(&sem_ids(ns).mutex);
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700152
153 in_use = sem_ids(ns).in_use;
154
155 for (total = 0, next_id = 0; total < in_use; next_id++) {
156 sma = idr_find(&sem_ids(ns).ipcs_idr, next_id);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700157 if (sma == NULL)
158 continue;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700159 ipc_lock_by_ptr(&sma->sem_perm);
160 freeary(ns, sma);
161 total++;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700162 }
163 mutex_unlock(&sem_ids(ns).mutex);
164
165 kfree(ns->ids[IPC_SEM_IDS]);
166 ns->ids[IPC_SEM_IDS] = NULL;
167}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
169void __init sem_init (void)
170{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700171 __sem_init_ns(&init_ipc_ns, &init_sem_ids);
Mike Waychison19b49462005-09-06 15:17:10 -0700172 ipc_init_proc_interface("sysvipc/sem",
173 " key semid perms nsems uid gid cuid cgid otime ctime\n",
Kirill Korotaeve3893532006-10-02 02:18:22 -0700174 IPC_SEM_IDS, sysvipc_sem_proc_show);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175}
176
Nadia Derbey023a5352007-10-18 23:40:51 -0700177static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
178{
179 return (struct sem_array *) ipc_lock(&sem_ids(ns), id);
180}
181
182static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
183 int id)
184{
185 return (struct sem_array *) ipc_lock_check(&sem_ids(ns), id);
186}
187
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700188static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
189{
190 ipc_rmid(&sem_ids(ns), &s->sem_perm);
191}
192
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193/*
194 * Lockless wakeup algorithm:
195 * Without the check/retry algorithm a lockless wakeup is possible:
196 * - queue.status is initialized to -EINTR before blocking.
197 * - wakeup is performed by
198 * * unlinking the queue entry from sma->sem_pending
199 * * setting queue.status to IN_WAKEUP
200 * This is the notification for the blocked thread that a
201 * result value is imminent.
202 * * call wake_up_process
203 * * set queue.status to the final value.
204 * - the previously blocked thread checks queue.status:
205 * * if it's IN_WAKEUP, then it must wait until the value changes
206 * * if it's not -EINTR, then the operation was completed by
207 * update_queue. semtimedop can return queue.status without
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800208 * performing any operation on the sem array.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 * * otherwise it must acquire the spinlock and check what's up.
210 *
211 * The two-stage algorithm is necessary to protect against the following
212 * races:
213 * - if queue.status is set after wake_up_process, then the woken up idle
214 * thread could race forward and try (and fail) to acquire sma->lock
215 * before update_queue had a chance to set queue.status
216 * - if queue.status is written before wake_up_process and if the
217 * blocked process is woken up by a signal between writing
218 * queue.status and the wake_up_process, then the woken up
219 * process could return from semtimedop and die by calling
220 * sys_exit before wake_up_process is called. Then wake_up_process
221 * will oops, because the task structure is already invalid.
222 * (yes, this happened on s390 with sysv msg).
223 *
224 */
225#define IN_WAKEUP 1
226
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700227static int newary(struct ipc_namespace *ns, struct ipc_params *params)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228{
229 int id;
230 int retval;
231 struct sem_array *sma;
232 int size;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700233 key_t key = params->key;
234 int nsems = params->u.nsems;
235 int semflg = params->flg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
237 if (!nsems)
238 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700239 if (ns->used_sems + nsems > ns->sc_semmns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 return -ENOSPC;
241
242 size = sizeof (*sma) + nsems * sizeof (struct sem);
243 sma = ipc_rcu_alloc(size);
244 if (!sma) {
245 return -ENOMEM;
246 }
247 memset (sma, 0, size);
248
249 sma->sem_perm.mode = (semflg & S_IRWXUGO);
250 sma->sem_perm.key = key;
251
252 sma->sem_perm.security = NULL;
253 retval = security_sem_alloc(sma);
254 if (retval) {
255 ipc_rcu_putref(sma);
256 return retval;
257 }
258
Kirill Korotaeve3893532006-10-02 02:18:22 -0700259 id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 if(id == -1) {
261 security_sem_free(sma);
262 ipc_rcu_putref(sma);
263 return -ENOSPC;
264 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700265 ns->used_sems += nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700267 sma->sem_perm.id = sem_buildid(ns, id, sma->sem_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 sma->sem_base = (struct sem *) &sma[1];
269 /* sma->sem_pending = NULL; */
270 sma->sem_pending_last = &sma->sem_pending;
271 /* sma->undo = NULL; */
272 sma->sem_nsems = nsems;
273 sma->sem_ctime = get_seconds();
274 sem_unlock(sma);
275
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700276 return sma->sem_perm.id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277}
278
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700279
280static inline int sem_security(void *sma, int semflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281{
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700282 return security_sem_associate((struct sem_array *) sma, semflg);
283}
284
285static inline int sem_more_checks(void *sma, struct ipc_params *params)
286{
287 if (params->u.nsems > ((struct sem_array *)sma)->sem_nsems)
288 return -EINVAL;
289
290 return 0;
291}
292
293asmlinkage long sys_semget(key_t key, int nsems, int semflg)
294{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700295 struct ipc_namespace *ns;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700296 struct ipc_ops sem_ops;
297 struct ipc_params sem_params;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298
Kirill Korotaeve3893532006-10-02 02:18:22 -0700299 ns = current->nsproxy->ipc_ns;
300
301 if (nsems < 0 || nsems > ns->sc_semmsl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 return -EINVAL;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700303
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700304 sem_ops.getnew = newary;
305 sem_ops.associate = sem_security;
306 sem_ops.more_checks = sem_more_checks;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700307
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700308 sem_params.key = key;
309 sem_params.flg = semflg;
310 sem_params.u.nsems = nsems;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700311
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700312 return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313}
314
315/* Manage the doubly linked list sma->sem_pending as a FIFO:
316 * insert new queue elements at the tail sma->sem_pending_last.
317 */
318static inline void append_to_queue (struct sem_array * sma,
319 struct sem_queue * q)
320{
321 *(q->prev = sma->sem_pending_last) = q;
322 *(sma->sem_pending_last = &q->next) = NULL;
323}
324
325static inline void prepend_to_queue (struct sem_array * sma,
326 struct sem_queue * q)
327{
328 q->next = sma->sem_pending;
329 *(q->prev = &sma->sem_pending) = q;
330 if (q->next)
331 q->next->prev = &q->next;
332 else /* sma->sem_pending_last == &sma->sem_pending */
333 sma->sem_pending_last = &q->next;
334}
335
336static inline void remove_from_queue (struct sem_array * sma,
337 struct sem_queue * q)
338{
339 *(q->prev) = q->next;
340 if (q->next)
341 q->next->prev = q->prev;
342 else /* sma->sem_pending_last == &q->next */
343 sma->sem_pending_last = q->prev;
344 q->prev = NULL; /* mark as removed */
345}
346
347/*
348 * Determine whether a sequence of semaphore operations would succeed
349 * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
350 */
351
352static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
353 int nsops, struct sem_undo *un, int pid)
354{
355 int result, sem_op;
356 struct sembuf *sop;
357 struct sem * curr;
358
359 for (sop = sops; sop < sops + nsops; sop++) {
360 curr = sma->sem_base + sop->sem_num;
361 sem_op = sop->sem_op;
362 result = curr->semval;
363
364 if (!sem_op && result)
365 goto would_block;
366
367 result += sem_op;
368 if (result < 0)
369 goto would_block;
370 if (result > SEMVMX)
371 goto out_of_range;
372 if (sop->sem_flg & SEM_UNDO) {
373 int undo = un->semadj[sop->sem_num] - sem_op;
374 /*
375 * Exceeding the undo range is an error.
376 */
377 if (undo < (-SEMAEM - 1) || undo > SEMAEM)
378 goto out_of_range;
379 }
380 curr->semval = result;
381 }
382
383 sop--;
384 while (sop >= sops) {
385 sma->sem_base[sop->sem_num].sempid = pid;
386 if (sop->sem_flg & SEM_UNDO)
387 un->semadj[sop->sem_num] -= sop->sem_op;
388 sop--;
389 }
390
391 sma->sem_otime = get_seconds();
392 return 0;
393
394out_of_range:
395 result = -ERANGE;
396 goto undo;
397
398would_block:
399 if (sop->sem_flg & IPC_NOWAIT)
400 result = -EAGAIN;
401 else
402 result = 1;
403
404undo:
405 sop--;
406 while (sop >= sops) {
407 sma->sem_base[sop->sem_num].semval -= sop->sem_op;
408 sop--;
409 }
410
411 return result;
412}
413
414/* Go through the pending queue for the indicated semaphore
415 * looking for tasks that can be completed.
416 */
417static void update_queue (struct sem_array * sma)
418{
419 int error;
420 struct sem_queue * q;
421
422 q = sma->sem_pending;
423 while(q) {
424 error = try_atomic_semop(sma, q->sops, q->nsops,
425 q->undo, q->pid);
426
427 /* Does q->sleeper still need to sleep? */
428 if (error <= 0) {
429 struct sem_queue *n;
430 remove_from_queue(sma,q);
431 q->status = IN_WAKEUP;
432 /*
433 * Continue scanning. The next operation
434 * that must be checked depends on the type of the
435 * completed operation:
436 * - if the operation modified the array, then
437 * restart from the head of the queue and
438 * check for threads that might be waiting
439 * for semaphore values to become 0.
440 * - if the operation didn't modify the array,
441 * then just continue.
442 */
443 if (q->alter)
444 n = sma->sem_pending;
445 else
446 n = q->next;
447 wake_up_process(q->sleeper);
448 /* hands-off: q will disappear immediately after
449 * writing q->status.
450 */
Linus Torvalds1224b372005-12-24 12:19:38 -0800451 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 q->status = error;
453 q = n;
454 } else {
455 q = q->next;
456 }
457 }
458}
459
460/* The following counts are associated to each semaphore:
461 * semncnt number of tasks waiting on semval being nonzero
462 * semzcnt number of tasks waiting on semval being zero
463 * This model assumes that a task waits on exactly one semaphore.
464 * Since semaphore operations are to be performed atomically, tasks actually
465 * wait on a whole sequence of semaphores simultaneously.
466 * The counts we return here are a rough approximation, but still
467 * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
468 */
469static int count_semncnt (struct sem_array * sma, ushort semnum)
470{
471 int semncnt;
472 struct sem_queue * q;
473
474 semncnt = 0;
475 for (q = sma->sem_pending; q; q = q->next) {
476 struct sembuf * sops = q->sops;
477 int nsops = q->nsops;
478 int i;
479 for (i = 0; i < nsops; i++)
480 if (sops[i].sem_num == semnum
481 && (sops[i].sem_op < 0)
482 && !(sops[i].sem_flg & IPC_NOWAIT))
483 semncnt++;
484 }
485 return semncnt;
486}
487static int count_semzcnt (struct sem_array * sma, ushort semnum)
488{
489 int semzcnt;
490 struct sem_queue * q;
491
492 semzcnt = 0;
493 for (q = sma->sem_pending; q; q = q->next) {
494 struct sembuf * sops = q->sops;
495 int nsops = q->nsops;
496 int i;
497 for (i = 0; i < nsops; i++)
498 if (sops[i].sem_num == semnum
499 && (sops[i].sem_op == 0)
500 && !(sops[i].sem_flg & IPC_NOWAIT))
501 semzcnt++;
502 }
503 return semzcnt;
504}
505
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800506/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
507 * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 * on exit.
509 */
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700510static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511{
512 struct sem_undo *un;
513 struct sem_queue *q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
515 /* Invalidate the existing undo structures for this semaphore set.
516 * (They will be freed without any further action in exit_sem()
517 * or during the next semop.)
518 */
519 for (un = sma->undo; un; un = un->id_next)
520 un->semid = -1;
521
522 /* Wake up all pending processes and let them fail with EIDRM. */
523 q = sma->sem_pending;
524 while(q) {
525 struct sem_queue *n;
526 /* lazy remove_from_queue: we are killing the whole queue */
527 q->prev = NULL;
528 n = q->next;
529 q->status = IN_WAKEUP;
530 wake_up_process(q->sleeper); /* doesn't sleep */
Manfred Spraul6003a932005-12-23 23:57:41 +0100531 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 q->status = -EIDRM; /* hands-off q */
533 q = n;
534 }
535
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700536 /* Remove the semaphore set from the IDR */
537 sem_rmid(ns, sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 sem_unlock(sma);
539
Kirill Korotaeve3893532006-10-02 02:18:22 -0700540 ns->used_sems -= sma->sem_nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 security_sem_free(sma);
542 ipc_rcu_putref(sma);
543}
544
545static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
546{
547 switch(version) {
548 case IPC_64:
549 return copy_to_user(buf, in, sizeof(*in));
550 case IPC_OLD:
551 {
552 struct semid_ds out;
553
554 ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
555
556 out.sem_otime = in->sem_otime;
557 out.sem_ctime = in->sem_ctime;
558 out.sem_nsems = in->sem_nsems;
559
560 return copy_to_user(buf, &out, sizeof(out));
561 }
562 default:
563 return -EINVAL;
564 }
565}
566
Kirill Korotaeve3893532006-10-02 02:18:22 -0700567static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
568 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569{
570 int err = -EINVAL;
571 struct sem_array *sma;
572
573 switch(cmd) {
574 case IPC_INFO:
575 case SEM_INFO:
576 {
577 struct seminfo seminfo;
578 int max_id;
579
580 err = security_sem_semctl(NULL, cmd);
581 if (err)
582 return err;
583
584 memset(&seminfo,0,sizeof(seminfo));
Kirill Korotaeve3893532006-10-02 02:18:22 -0700585 seminfo.semmni = ns->sc_semmni;
586 seminfo.semmns = ns->sc_semmns;
587 seminfo.semmsl = ns->sc_semmsl;
588 seminfo.semopm = ns->sc_semopm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 seminfo.semvmx = SEMVMX;
590 seminfo.semmnu = SEMMNU;
591 seminfo.semmap = SEMMAP;
592 seminfo.semume = SEMUME;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700593 mutex_lock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 if (cmd == SEM_INFO) {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700595 seminfo.semusz = sem_ids(ns).in_use;
596 seminfo.semaem = ns->used_sems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 } else {
598 seminfo.semusz = SEMUSZ;
599 seminfo.semaem = SEMAEM;
600 }
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700601 max_id = ipc_get_maxid(&sem_ids(ns));
Kirill Korotaeve3893532006-10-02 02:18:22 -0700602 mutex_unlock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
604 return -EFAULT;
605 return (max_id < 0) ? 0: max_id;
606 }
607 case SEM_STAT:
608 {
609 struct semid64_ds tbuf;
610 int id;
611
Kirill Korotaeve3893532006-10-02 02:18:22 -0700612 sma = sem_lock(ns, semid);
Nadia Derbey023a5352007-10-18 23:40:51 -0700613 if (IS_ERR(sma))
614 return PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
616 err = -EACCES;
617 if (ipcperms (&sma->sem_perm, S_IRUGO))
618 goto out_unlock;
619
620 err = security_sem_semctl(sma, cmd);
621 if (err)
622 goto out_unlock;
623
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700624 id = sma->sem_perm.id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625
Nadia Derbey023a5352007-10-18 23:40:51 -0700626 memset(&tbuf, 0, sizeof(tbuf));
627
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
629 tbuf.sem_otime = sma->sem_otime;
630 tbuf.sem_ctime = sma->sem_ctime;
631 tbuf.sem_nsems = sma->sem_nsems;
632 sem_unlock(sma);
633 if (copy_semid_to_user (arg.buf, &tbuf, version))
634 return -EFAULT;
635 return id;
636 }
637 default:
638 return -EINVAL;
639 }
640 return err;
641out_unlock:
642 sem_unlock(sma);
643 return err;
644}
645
Kirill Korotaeve3893532006-10-02 02:18:22 -0700646static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
647 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648{
649 struct sem_array *sma;
650 struct sem* curr;
651 int err;
652 ushort fast_sem_io[SEMMSL_FAST];
653 ushort* sem_io = fast_sem_io;
654 int nsems;
655
Nadia Derbey023a5352007-10-18 23:40:51 -0700656 sma = sem_lock_check(ns, semid);
657 if (IS_ERR(sma))
658 return PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660 nsems = sma->sem_nsems;
661
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 err = -EACCES;
663 if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
664 goto out_unlock;
665
666 err = security_sem_semctl(sma, cmd);
667 if (err)
668 goto out_unlock;
669
670 err = -EACCES;
671 switch (cmd) {
672 case GETALL:
673 {
674 ushort __user *array = arg.array;
675 int i;
676
677 if(nsems > SEMMSL_FAST) {
678 ipc_rcu_getref(sma);
679 sem_unlock(sma);
680
681 sem_io = ipc_alloc(sizeof(ushort)*nsems);
682 if(sem_io == NULL) {
683 ipc_lock_by_ptr(&sma->sem_perm);
684 ipc_rcu_putref(sma);
685 sem_unlock(sma);
686 return -ENOMEM;
687 }
688
689 ipc_lock_by_ptr(&sma->sem_perm);
690 ipc_rcu_putref(sma);
691 if (sma->sem_perm.deleted) {
692 sem_unlock(sma);
693 err = -EIDRM;
694 goto out_free;
695 }
696 }
697
698 for (i = 0; i < sma->sem_nsems; i++)
699 sem_io[i] = sma->sem_base[i].semval;
700 sem_unlock(sma);
701 err = 0;
702 if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
703 err = -EFAULT;
704 goto out_free;
705 }
706 case SETALL:
707 {
708 int i;
709 struct sem_undo *un;
710
711 ipc_rcu_getref(sma);
712 sem_unlock(sma);
713
714 if(nsems > SEMMSL_FAST) {
715 sem_io = ipc_alloc(sizeof(ushort)*nsems);
716 if(sem_io == NULL) {
717 ipc_lock_by_ptr(&sma->sem_perm);
718 ipc_rcu_putref(sma);
719 sem_unlock(sma);
720 return -ENOMEM;
721 }
722 }
723
724 if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
725 ipc_lock_by_ptr(&sma->sem_perm);
726 ipc_rcu_putref(sma);
727 sem_unlock(sma);
728 err = -EFAULT;
729 goto out_free;
730 }
731
732 for (i = 0; i < nsems; i++) {
733 if (sem_io[i] > SEMVMX) {
734 ipc_lock_by_ptr(&sma->sem_perm);
735 ipc_rcu_putref(sma);
736 sem_unlock(sma);
737 err = -ERANGE;
738 goto out_free;
739 }
740 }
741 ipc_lock_by_ptr(&sma->sem_perm);
742 ipc_rcu_putref(sma);
743 if (sma->sem_perm.deleted) {
744 sem_unlock(sma);
745 err = -EIDRM;
746 goto out_free;
747 }
748
749 for (i = 0; i < nsems; i++)
750 sma->sem_base[i].semval = sem_io[i];
751 for (un = sma->undo; un; un = un->id_next)
752 for (i = 0; i < nsems; i++)
753 un->semadj[i] = 0;
754 sma->sem_ctime = get_seconds();
755 /* maybe some queued-up processes were waiting for this */
756 update_queue(sma);
757 err = 0;
758 goto out_unlock;
759 }
760 case IPC_STAT:
761 {
762 struct semid64_ds tbuf;
763 memset(&tbuf,0,sizeof(tbuf));
764 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
765 tbuf.sem_otime = sma->sem_otime;
766 tbuf.sem_ctime = sma->sem_ctime;
767 tbuf.sem_nsems = sma->sem_nsems;
768 sem_unlock(sma);
769 if (copy_semid_to_user (arg.buf, &tbuf, version))
770 return -EFAULT;
771 return 0;
772 }
773 /* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
774 }
775 err = -EINVAL;
776 if(semnum < 0 || semnum >= nsems)
777 goto out_unlock;
778
779 curr = &sma->sem_base[semnum];
780
781 switch (cmd) {
782 case GETVAL:
783 err = curr->semval;
784 goto out_unlock;
785 case GETPID:
786 err = curr->sempid;
787 goto out_unlock;
788 case GETNCNT:
789 err = count_semncnt(sma,semnum);
790 goto out_unlock;
791 case GETZCNT:
792 err = count_semzcnt(sma,semnum);
793 goto out_unlock;
794 case SETVAL:
795 {
796 int val = arg.val;
797 struct sem_undo *un;
798 err = -ERANGE;
799 if (val > SEMVMX || val < 0)
800 goto out_unlock;
801
802 for (un = sma->undo; un; un = un->id_next)
803 un->semadj[semnum] = 0;
804 curr->semval = val;
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700805 curr->sempid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 sma->sem_ctime = get_seconds();
807 /* maybe some queued-up processes were waiting for this */
808 update_queue(sma);
809 err = 0;
810 goto out_unlock;
811 }
812 }
813out_unlock:
814 sem_unlock(sma);
815out_free:
816 if(sem_io != fast_sem_io)
817 ipc_free(sem_io, sizeof(ushort)*nsems);
818 return err;
819}
820
821struct sem_setbuf {
822 uid_t uid;
823 gid_t gid;
824 mode_t mode;
825};
826
827static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
828{
829 switch(version) {
830 case IPC_64:
831 {
832 struct semid64_ds tbuf;
833
834 if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
835 return -EFAULT;
836
837 out->uid = tbuf.sem_perm.uid;
838 out->gid = tbuf.sem_perm.gid;
839 out->mode = tbuf.sem_perm.mode;
840
841 return 0;
842 }
843 case IPC_OLD:
844 {
845 struct semid_ds tbuf_old;
846
847 if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
848 return -EFAULT;
849
850 out->uid = tbuf_old.sem_perm.uid;
851 out->gid = tbuf_old.sem_perm.gid;
852 out->mode = tbuf_old.sem_perm.mode;
853
854 return 0;
855 }
856 default:
857 return -EINVAL;
858 }
859}
860
Kirill Korotaeve3893532006-10-02 02:18:22 -0700861static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
862 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863{
864 struct sem_array *sma;
865 int err;
Jeff Garzik8e1c0912007-07-17 05:40:59 -0400866 struct sem_setbuf uninitialized_var(setbuf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 struct kern_ipc_perm *ipcp;
868
869 if(cmd == IPC_SET) {
870 if(copy_semid_from_user (&setbuf, arg.buf, version))
871 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 }
Nadia Derbey023a5352007-10-18 23:40:51 -0700873 sma = sem_lock_check(ns, semid);
874 if (IS_ERR(sma))
875 return PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 ipcp = &sma->sem_perm;
Steve Grubb073115d2006-04-02 17:07:33 -0400878
879 err = audit_ipc_obj(ipcp);
880 if (err)
881 goto out_unlock;
882
Linda Knippersac032212006-05-16 22:03:48 -0400883 if (cmd == IPC_SET) {
884 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
885 if (err)
886 goto out_unlock;
887 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 if (current->euid != ipcp->cuid &&
889 current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
890 err=-EPERM;
891 goto out_unlock;
892 }
893
894 err = security_sem_semctl(sma, cmd);
895 if (err)
896 goto out_unlock;
897
898 switch(cmd){
899 case IPC_RMID:
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700900 freeary(ns, sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 err = 0;
902 break;
903 case IPC_SET:
904 ipcp->uid = setbuf.uid;
905 ipcp->gid = setbuf.gid;
906 ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
907 | (setbuf.mode & S_IRWXUGO);
908 sma->sem_ctime = get_seconds();
909 sem_unlock(sma);
910 err = 0;
911 break;
912 default:
913 sem_unlock(sma);
914 err = -EINVAL;
915 break;
916 }
917 return err;
918
919out_unlock:
920 sem_unlock(sma);
921 return err;
922}
923
924asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
925{
926 int err = -EINVAL;
927 int version;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700928 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929
930 if (semid < 0)
931 return -EINVAL;
932
933 version = ipc_parse_version(&cmd);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700934 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
936 switch(cmd) {
937 case IPC_INFO:
938 case SEM_INFO:
939 case SEM_STAT:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700940 err = semctl_nolock(ns,semid,semnum,cmd,version,arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 return err;
942 case GETALL:
943 case GETVAL:
944 case GETPID:
945 case GETNCNT:
946 case GETZCNT:
947 case IPC_STAT:
948 case SETVAL:
949 case SETALL:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700950 err = semctl_main(ns,semid,semnum,cmd,version,arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 return err;
952 case IPC_RMID:
953 case IPC_SET:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700954 mutex_lock(&sem_ids(ns).mutex);
955 err = semctl_down(ns,semid,semnum,cmd,version,arg);
956 mutex_unlock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957 return err;
958 default:
959 return -EINVAL;
960 }
961}
962
963static inline void lock_semundo(void)
964{
965 struct sem_undo_list *undo_list;
966
967 undo_list = current->sysvsem.undo_list;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +0200968 if (undo_list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 spin_lock(&undo_list->lock);
970}
971
972/* This code has an interaction with copy_semundo().
973 * Consider; two tasks are sharing the undo_list. task1
974 * acquires the undo_list lock in lock_semundo(). If task2 now
975 * exits before task1 releases the lock (by calling
976 * unlock_semundo()), then task1 will never call spin_unlock().
977 * This leave the sem_undo_list in a locked state. If task1 now creats task3
978 * and once again shares the sem_undo_list, the sem_undo_list will still be
979 * locked, and future SEM_UNDO operations will deadlock. This case is
980 * dealt with in copy_semundo() by having it reinitialize the spin lock when
981 * the refcnt goes from 1 to 2.
982 */
983static inline void unlock_semundo(void)
984{
985 struct sem_undo_list *undo_list;
986
987 undo_list = current->sysvsem.undo_list;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +0200988 if (undo_list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 spin_unlock(&undo_list->lock);
990}
991
992
993/* If the task doesn't already have a undo_list, then allocate one
994 * here. We guarantee there is only one thread using this undo list,
995 * and current is THE ONE
996 *
997 * If this allocation and assignment succeeds, but later
998 * portions of this code fail, there is no need to free the sem_undo_list.
999 * Just let it stay associated with the task, and it'll be freed later
1000 * at exit time.
1001 *
1002 * This can block, so callers must hold no locks.
1003 */
1004static inline int get_undo_list(struct sem_undo_list **undo_listp)
1005{
1006 struct sem_undo_list *undo_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007
1008 undo_list = current->sysvsem.undo_list;
1009 if (!undo_list) {
Matt Helsley2453a302006-10-02 02:18:25 -07001010 undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 if (undo_list == NULL)
1012 return -ENOMEM;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +02001013 spin_lock_init(&undo_list->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 atomic_set(&undo_list->refcnt, 1);
1015 current->sysvsem.undo_list = undo_list;
1016 }
1017 *undo_listp = undo_list;
1018 return 0;
1019}
1020
1021static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1022{
1023 struct sem_undo **last, *un;
1024
1025 last = &ulp->proc_list;
1026 un = *last;
1027 while(un != NULL) {
1028 if(un->semid==semid)
1029 break;
1030 if(un->semid==-1) {
1031 *last=un->proc_next;
1032 kfree(un);
1033 } else {
1034 last=&un->proc_next;
1035 }
1036 un=*last;
1037 }
1038 return un;
1039}
1040
Kirill Korotaeve3893532006-10-02 02:18:22 -07001041static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042{
1043 struct sem_array *sma;
1044 struct sem_undo_list *ulp;
1045 struct sem_undo *un, *new;
1046 int nsems;
1047 int error;
1048
1049 error = get_undo_list(&ulp);
1050 if (error)
1051 return ERR_PTR(error);
1052
1053 lock_semundo();
1054 un = lookup_undo(ulp, semid);
1055 unlock_semundo();
1056 if (likely(un!=NULL))
1057 goto out;
1058
1059 /* no undo structure around - allocate one. */
Nadia Derbey023a5352007-10-18 23:40:51 -07001060 sma = sem_lock_check(ns, semid);
1061 if (IS_ERR(sma))
1062 return ERR_PTR(PTR_ERR(sma));
1063
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 nsems = sma->sem_nsems;
1065 ipc_rcu_getref(sma);
1066 sem_unlock(sma);
1067
Burman Yan4668edc2006-12-06 20:38:51 -08001068 new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 if (!new) {
1070 ipc_lock_by_ptr(&sma->sem_perm);
1071 ipc_rcu_putref(sma);
1072 sem_unlock(sma);
1073 return ERR_PTR(-ENOMEM);
1074 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 new->semadj = (short *) &new[1];
1076 new->semid = semid;
1077
1078 lock_semundo();
1079 un = lookup_undo(ulp, semid);
1080 if (un) {
1081 unlock_semundo();
1082 kfree(new);
1083 ipc_lock_by_ptr(&sma->sem_perm);
1084 ipc_rcu_putref(sma);
1085 sem_unlock(sma);
1086 goto out;
1087 }
1088 ipc_lock_by_ptr(&sma->sem_perm);
1089 ipc_rcu_putref(sma);
1090 if (sma->sem_perm.deleted) {
1091 sem_unlock(sma);
1092 unlock_semundo();
1093 kfree(new);
1094 un = ERR_PTR(-EIDRM);
1095 goto out;
1096 }
1097 new->proc_next = ulp->proc_list;
1098 ulp->proc_list = new;
1099 new->id_next = sma->undo;
1100 sma->undo = new;
1101 sem_unlock(sma);
1102 un = new;
1103 unlock_semundo();
1104out:
1105 return un;
1106}
1107
1108asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops,
1109 unsigned nsops, const struct timespec __user *timeout)
1110{
1111 int error = -EINVAL;
1112 struct sem_array *sma;
1113 struct sembuf fast_sops[SEMOPM_FAST];
1114 struct sembuf* sops = fast_sops, *sop;
1115 struct sem_undo *un;
Manfred Spraulb78755a2005-06-23 00:10:06 -07001116 int undos = 0, alter = 0, max;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 struct sem_queue queue;
1118 unsigned long jiffies_left = 0;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001119 struct ipc_namespace *ns;
1120
1121 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122
1123 if (nsops < 1 || semid < 0)
1124 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001125 if (nsops > ns->sc_semopm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 return -E2BIG;
1127 if(nsops > SEMOPM_FAST) {
1128 sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
1129 if(sops==NULL)
1130 return -ENOMEM;
1131 }
1132 if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1133 error=-EFAULT;
1134 goto out_free;
1135 }
1136 if (timeout) {
1137 struct timespec _timeout;
1138 if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1139 error = -EFAULT;
1140 goto out_free;
1141 }
1142 if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1143 _timeout.tv_nsec >= 1000000000L) {
1144 error = -EINVAL;
1145 goto out_free;
1146 }
1147 jiffies_left = timespec_to_jiffies(&_timeout);
1148 }
1149 max = 0;
1150 for (sop = sops; sop < sops + nsops; sop++) {
1151 if (sop->sem_num >= max)
1152 max = sop->sem_num;
1153 if (sop->sem_flg & SEM_UNDO)
Manfred Spraulb78755a2005-06-23 00:10:06 -07001154 undos = 1;
1155 if (sop->sem_op != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 alter = 1;
1157 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158
1159retry_undos:
1160 if (undos) {
Kirill Korotaeve3893532006-10-02 02:18:22 -07001161 un = find_undo(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 if (IS_ERR(un)) {
1163 error = PTR_ERR(un);
1164 goto out_free;
1165 }
1166 } else
1167 un = NULL;
1168
Nadia Derbey023a5352007-10-18 23:40:51 -07001169 sma = sem_lock_check(ns, semid);
1170 if (IS_ERR(sma)) {
1171 error = PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 goto out_free;
Nadia Derbey023a5352007-10-18 23:40:51 -07001173 }
1174
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 /*
Nadia Derbey023a5352007-10-18 23:40:51 -07001176 * semid identifiers are not unique - find_undo may have
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 * allocated an undo structure, it was invalidated by an RMID
1178 * and now a new array with received the same id. Check and retry.
1179 */
1180 if (un && un->semid == -1) {
1181 sem_unlock(sma);
1182 goto retry_undos;
1183 }
1184 error = -EFBIG;
1185 if (max >= sma->sem_nsems)
1186 goto out_unlock_free;
1187
1188 error = -EACCES;
1189 if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1190 goto out_unlock_free;
1191
1192 error = security_sem_semop(sma, sops, nsops, alter);
1193 if (error)
1194 goto out_unlock_free;
1195
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001196 error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 if (error <= 0) {
1198 if (alter && error == 0)
1199 update_queue (sma);
1200 goto out_unlock_free;
1201 }
1202
1203 /* We need to sleep on this operation, so we put the current
1204 * task into the pending queue and go to sleep.
1205 */
1206
1207 queue.sma = sma;
1208 queue.sops = sops;
1209 queue.nsops = nsops;
1210 queue.undo = un;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001211 queue.pid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 queue.id = semid;
1213 queue.alter = alter;
1214 if (alter)
1215 append_to_queue(sma ,&queue);
1216 else
1217 prepend_to_queue(sma ,&queue);
1218
1219 queue.status = -EINTR;
1220 queue.sleeper = current;
1221 current->state = TASK_INTERRUPTIBLE;
1222 sem_unlock(sma);
1223
1224 if (timeout)
1225 jiffies_left = schedule_timeout(jiffies_left);
1226 else
1227 schedule();
1228
1229 error = queue.status;
1230 while(unlikely(error == IN_WAKEUP)) {
1231 cpu_relax();
1232 error = queue.status;
1233 }
1234
1235 if (error != -EINTR) {
1236 /* fast path: update_queue already obtained all requested
1237 * resources */
1238 goto out_free;
1239 }
1240
Kirill Korotaeve3893532006-10-02 02:18:22 -07001241 sma = sem_lock(ns, semid);
Nadia Derbey023a5352007-10-18 23:40:51 -07001242 if (IS_ERR(sma)) {
Eric Sesterhenn27315c92006-03-26 18:28:38 +02001243 BUG_ON(queue.prev != NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 error = -EIDRM;
1245 goto out_free;
1246 }
1247
1248 /*
1249 * If queue.status != -EINTR we are woken up by another process
1250 */
1251 error = queue.status;
1252 if (error != -EINTR) {
1253 goto out_unlock_free;
1254 }
1255
1256 /*
1257 * If an interrupt occurred we have to clean up the queue
1258 */
1259 if (timeout && jiffies_left == 0)
1260 error = -EAGAIN;
1261 remove_from_queue(sma,&queue);
1262 goto out_unlock_free;
1263
1264out_unlock_free:
1265 sem_unlock(sma);
1266out_free:
1267 if(sops != fast_sops)
1268 kfree(sops);
1269 return error;
1270}
1271
1272asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsops)
1273{
1274 return sys_semtimedop(semid, tsops, nsops, NULL);
1275}
1276
1277/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1278 * parent and child tasks.
1279 *
1280 * See the notes above unlock_semundo() regarding the spin_lock_init()
1281 * in this code. Initialize the undo_list->lock here instead of get_undo_list()
1282 * because of the reasoning in the comment above unlock_semundo.
1283 */
1284
1285int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1286{
1287 struct sem_undo_list *undo_list;
1288 int error;
1289
1290 if (clone_flags & CLONE_SYSVSEM) {
1291 error = get_undo_list(&undo_list);
1292 if (error)
1293 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 atomic_inc(&undo_list->refcnt);
1295 tsk->sysvsem.undo_list = undo_list;
1296 } else
1297 tsk->sysvsem.undo_list = NULL;
1298
1299 return 0;
1300}
1301
1302/*
1303 * add semadj values to semaphores, free undo structures.
1304 * undo structures are not freed when semaphore arrays are destroyed
1305 * so some of them may be out of date.
1306 * IMPLEMENTATION NOTE: There is some confusion over whether the
1307 * set of adjustments that needs to be done should be done in an atomic
1308 * manner or not. That is, if we are attempting to decrement the semval
1309 * should we queue up and wait until we can do so legally?
1310 * The original implementation attempted to do this (queue and wait).
1311 * The current implementation does not do so. The POSIX standard
1312 * and SVID should be consulted to determine what behavior is mandated.
1313 */
1314void exit_sem(struct task_struct *tsk)
1315{
1316 struct sem_undo_list *undo_list;
1317 struct sem_undo *u, **up;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001318 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319
1320 undo_list = tsk->sysvsem.undo_list;
1321 if (!undo_list)
1322 return;
1323
1324 if (!atomic_dec_and_test(&undo_list->refcnt))
1325 return;
1326
Kirill Korotaeve3893532006-10-02 02:18:22 -07001327 ns = tsk->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 /* There's no need to hold the semundo list lock, as current
1329 * is the last task exiting for this undo list.
1330 */
1331 for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
1332 struct sem_array *sma;
1333 int nsems, i;
1334 struct sem_undo *un, **unp;
1335 int semid;
1336
1337 semid = u->semid;
1338
1339 if(semid == -1)
1340 continue;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001341 sma = sem_lock(ns, semid);
Nadia Derbey023a5352007-10-18 23:40:51 -07001342 if (IS_ERR(sma))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 continue;
1344
1345 if (u->semid == -1)
1346 goto next_entry;
1347
Kirill Korotaeve3893532006-10-02 02:18:22 -07001348 BUG_ON(sem_checkid(ns,sma,u->semid));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
1350 /* remove u from the sma->undo list */
1351 for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
1352 if (u == un)
1353 goto found;
1354 }
1355 printk ("exit_sem undo list error id=%d\n", u->semid);
1356 goto next_entry;
1357found:
1358 *unp = un->id_next;
1359 /* perform adjustments registered in u */
1360 nsems = sma->sem_nsems;
1361 for (i = 0; i < nsems; i++) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001362 struct sem * semaphore = &sma->sem_base[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 if (u->semadj[i]) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001364 semaphore->semval += u->semadj[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 /*
1366 * Range checks of the new semaphore value,
1367 * not defined by sus:
1368 * - Some unices ignore the undo entirely
1369 * (e.g. HP UX 11i 11.22, Tru64 V5.1)
1370 * - some cap the value (e.g. FreeBSD caps
1371 * at 0, but doesn't enforce SEMVMX)
1372 *
1373 * Linux caps the semaphore value, both at 0
1374 * and at SEMVMX.
1375 *
1376 * Manfred <manfred@colorfullife.com>
1377 */
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001378 if (semaphore->semval < 0)
1379 semaphore->semval = 0;
1380 if (semaphore->semval > SEMVMX)
1381 semaphore->semval = SEMVMX;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001382 semaphore->sempid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 }
1384 }
1385 sma->sem_otime = get_seconds();
1386 /* maybe some queued-up processes were waiting for this */
1387 update_queue(sma);
1388next_entry:
1389 sem_unlock(sma);
1390 }
1391 kfree(undo_list);
1392}
1393
1394#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -07001395static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396{
Mike Waychison19b49462005-09-06 15:17:10 -07001397 struct sem_array *sma = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398
Mike Waychison19b49462005-09-06 15:17:10 -07001399 return seq_printf(s,
1400 "%10d %10d %4o %10lu %5u %5u %5u %5u %10lu %10lu\n",
1401 sma->sem_perm.key,
Nadia Derbey7ca7e562007-10-18 23:40:48 -07001402 sma->sem_perm.id,
Mike Waychison19b49462005-09-06 15:17:10 -07001403 sma->sem_perm.mode,
1404 sma->sem_nsems,
1405 sma->sem_perm.uid,
1406 sma->sem_perm.gid,
1407 sma->sem_perm.cuid,
1408 sma->sem_perm.cgid,
1409 sma->sem_otime,
1410 sma->sem_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411}
1412#endif