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1da177e4 LT |
1 | /* |
2 | * linux/ipc/sem.c | |
3 | * Copyright (C) 1992 Krishna Balasubramanian | |
4 | * Copyright (C) 1995 Eric Schenk, Bruno Haible | |
5 | * | |
1da177e4 LT |
6 | * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
7 | * | |
8 | * SMP-threaded, sysctl's added | |
624dffcb | 9 | * (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
1da177e4 | 10 | * Enforced range limit on SEM_UNDO |
046c6884 | 11 | * (c) 2001 Red Hat Inc |
1da177e4 LT |
12 | * Lockless wakeup |
13 | * (c) 2003 Manfred Spraul <manfred@colorfullife.com> | |
c5cf6359 MS |
14 | * Further wakeup optimizations, documentation |
15 | * (c) 2010 Manfred Spraul <manfred@colorfullife.com> | |
073115d6 SG |
16 | * |
17 | * support for audit of ipc object properties and permission changes | |
18 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> | |
e3893534 KK |
19 | * |
20 | * namespaces support | |
21 | * OpenVZ, SWsoft Inc. | |
22 | * Pavel Emelianov <xemul@openvz.org> | |
c5cf6359 MS |
23 | * |
24 | * Implementation notes: (May 2010) | |
25 | * This file implements System V semaphores. | |
26 | * | |
27 | * User space visible behavior: | |
28 | * - FIFO ordering for semop() operations (just FIFO, not starvation | |
29 | * protection) | |
30 | * - multiple semaphore operations that alter the same semaphore in | |
31 | * one semop() are handled. | |
32 | * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and | |
33 | * SETALL calls. | |
34 | * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO. | |
35 | * - undo adjustments at process exit are limited to 0..SEMVMX. | |
36 | * - namespace are supported. | |
37 | * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing | |
38 | * to /proc/sys/kernel/sem. | |
39 | * - statistics about the usage are reported in /proc/sysvipc/sem. | |
40 | * | |
41 | * Internals: | |
42 | * - scalability: | |
43 | * - all global variables are read-mostly. | |
44 | * - semop() calls and semctl(RMID) are synchronized by RCU. | |
45 | * - most operations do write operations (actually: spin_lock calls) to | |
46 | * the per-semaphore array structure. | |
47 | * Thus: Perfect SMP scaling between independent semaphore arrays. | |
48 | * If multiple semaphores in one array are used, then cache line | |
49 | * trashing on the semaphore array spinlock will limit the scaling. | |
50 | * - semncnt and semzcnt are calculated on demand in count_semncnt() and | |
51 | * count_semzcnt() | |
52 | * - the task that performs a successful semop() scans the list of all | |
53 | * sleeping tasks and completes any pending operations that can be fulfilled. | |
54 | * Semaphores are actively given to waiting tasks (necessary for FIFO). | |
55 | * (see update_queue()) | |
56 | * - To improve the scalability, the actual wake-up calls are performed after | |
57 | * dropping all locks. (see wake_up_sem_queue_prepare(), | |
58 | * wake_up_sem_queue_do()) | |
59 | * - All work is done by the waker, the woken up task does not have to do | |
60 | * anything - not even acquiring a lock or dropping a refcount. | |
61 | * - A woken up task may not even touch the semaphore array anymore, it may | |
62 | * have been destroyed already by a semctl(RMID). | |
63 | * - The synchronizations between wake-ups due to a timeout/signal and a | |
64 | * wake-up due to a completed semaphore operation is achieved by using an | |
65 | * intermediate state (IN_WAKEUP). | |
66 | * - UNDO values are stored in an array (one per process and per | |
67 | * semaphore array, lazily allocated). For backwards compatibility, multiple | |
68 | * modes for the UNDO variables are supported (per process, per thread) | |
69 | * (see copy_semundo, CLONE_SYSVSEM) | |
70 | * - There are two lists of the pending operations: a per-array list | |
71 | * and per-semaphore list (stored in the array). This allows to achieve FIFO | |
72 | * ordering without always scanning all pending operations. | |
73 | * The worst-case behavior is nevertheless O(N^2) for N wakeups. | |
1da177e4 LT |
74 | */ |
75 | ||
1da177e4 LT |
76 | #include <linux/slab.h> |
77 | #include <linux/spinlock.h> | |
78 | #include <linux/init.h> | |
79 | #include <linux/proc_fs.h> | |
80 | #include <linux/time.h> | |
1da177e4 LT |
81 | #include <linux/security.h> |
82 | #include <linux/syscalls.h> | |
83 | #include <linux/audit.h> | |
c59ede7b | 84 | #include <linux/capability.h> |
19b4946c | 85 | #include <linux/seq_file.h> |
3e148c79 | 86 | #include <linux/rwsem.h> |
e3893534 | 87 | #include <linux/nsproxy.h> |
ae5e1b22 | 88 | #include <linux/ipc_namespace.h> |
5f921ae9 | 89 | |
1da177e4 LT |
90 | #include <asm/uaccess.h> |
91 | #include "util.h" | |
92 | ||
e57940d7 MS |
93 | /* One semaphore structure for each semaphore in the system. */ |
94 | struct sem { | |
95 | int semval; /* current value */ | |
96 | int sempid; /* pid of last operation */ | |
6062a8dc | 97 | spinlock_t lock; /* spinlock for fine-grained semtimedop */ |
ab63bc97 MS |
98 | struct list_head pending_alter; /* pending single-sop operations */ |
99 | /* that alter the semaphore */ | |
100 | struct list_head pending_const; /* pending single-sop operations */ | |
101 | /* that do not alter the semaphore*/ | |
bf6830ad | 102 | time_t sem_otime; /* candidate for sem_otime */ |
0824e44c | 103 | } ____cacheline_aligned_in_smp; |
e57940d7 MS |
104 | |
105 | /* One queue for each sleeping process in the system. */ | |
106 | struct sem_queue { | |
e57940d7 MS |
107 | struct list_head list; /* queue of pending operations */ |
108 | struct task_struct *sleeper; /* this process */ | |
109 | struct sem_undo *undo; /* undo structure */ | |
110 | int pid; /* process id of requesting process */ | |
111 | int status; /* completion status of operation */ | |
112 | struct sembuf *sops; /* array of pending operations */ | |
113 | int nsops; /* number of operations */ | |
114 | int alter; /* does *sops alter the array? */ | |
115 | }; | |
116 | ||
117 | /* Each task has a list of undo requests. They are executed automatically | |
118 | * when the process exits. | |
119 | */ | |
120 | struct sem_undo { | |
121 | struct list_head list_proc; /* per-process list: * | |
122 | * all undos from one process | |
123 | * rcu protected */ | |
124 | struct rcu_head rcu; /* rcu struct for sem_undo */ | |
125 | struct sem_undo_list *ulp; /* back ptr to sem_undo_list */ | |
126 | struct list_head list_id; /* per semaphore array list: | |
127 | * all undos for one array */ | |
128 | int semid; /* semaphore set identifier */ | |
129 | short *semadj; /* array of adjustments */ | |
130 | /* one per semaphore */ | |
131 | }; | |
132 | ||
133 | /* sem_undo_list controls shared access to the list of sem_undo structures | |
134 | * that may be shared among all a CLONE_SYSVSEM task group. | |
135 | */ | |
136 | struct sem_undo_list { | |
137 | atomic_t refcnt; | |
138 | spinlock_t lock; | |
139 | struct list_head list_proc; | |
140 | }; | |
141 | ||
142 | ||
ed2ddbf8 | 143 | #define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS]) |
e3893534 | 144 | |
1b531f21 | 145 | #define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid) |
1da177e4 | 146 | |
7748dbfa | 147 | static int newary(struct ipc_namespace *, struct ipc_params *); |
01b8b07a | 148 | static void freeary(struct ipc_namespace *, struct kern_ipc_perm *); |
1da177e4 | 149 | #ifdef CONFIG_PROC_FS |
19b4946c | 150 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it); |
1da177e4 LT |
151 | #endif |
152 | ||
153 | #define SEMMSL_FAST 256 /* 512 bytes on stack */ | |
154 | #define SEMOPM_FAST 64 /* ~ 372 bytes on stack */ | |
155 | ||
156 | /* | |
b56e88e2 | 157 | * Locking: |
1da177e4 | 158 | * sem_undo.id_next, |
b56e88e2 | 159 | * sem_array.complex_count, |
ab63bc97 | 160 | * sem_array.pending{_alter,_cont}, |
b56e88e2 | 161 | * sem_array.sem_undo: global sem_lock() for read/write |
1da177e4 LT |
162 | * sem_undo.proc_next: only "current" is allowed to read/write that field. |
163 | * | |
b56e88e2 MS |
164 | * sem_array.sem_base[i].pending_{const,alter}: |
165 | * global or semaphore sem_lock() for read/write | |
1da177e4 LT |
166 | */ |
167 | ||
e3893534 KK |
168 | #define sc_semmsl sem_ctls[0] |
169 | #define sc_semmns sem_ctls[1] | |
170 | #define sc_semopm sem_ctls[2] | |
171 | #define sc_semmni sem_ctls[3] | |
172 | ||
ed2ddbf8 | 173 | void sem_init_ns(struct ipc_namespace *ns) |
e3893534 | 174 | { |
e3893534 KK |
175 | ns->sc_semmsl = SEMMSL; |
176 | ns->sc_semmns = SEMMNS; | |
177 | ns->sc_semopm = SEMOPM; | |
178 | ns->sc_semmni = SEMMNI; | |
179 | ns->used_sems = 0; | |
ed2ddbf8 | 180 | ipc_init_ids(&ns->ids[IPC_SEM_IDS]); |
e3893534 KK |
181 | } |
182 | ||
ae5e1b22 | 183 | #ifdef CONFIG_IPC_NS |
e3893534 KK |
184 | void sem_exit_ns(struct ipc_namespace *ns) |
185 | { | |
01b8b07a | 186 | free_ipcs(ns, &sem_ids(ns), freeary); |
7d6feeb2 | 187 | idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr); |
e3893534 | 188 | } |
ae5e1b22 | 189 | #endif |
1da177e4 LT |
190 | |
191 | void __init sem_init (void) | |
192 | { | |
ed2ddbf8 | 193 | sem_init_ns(&init_ipc_ns); |
19b4946c MW |
194 | ipc_init_proc_interface("sysvipc/sem", |
195 | " key semid perms nsems uid gid cuid cgid otime ctime\n", | |
e3893534 | 196 | IPC_SEM_IDS, sysvipc_sem_proc_show); |
1da177e4 LT |
197 | } |
198 | ||
e5639c52 MS |
199 | /** |
200 | * unmerge_queues - unmerge queues, if possible. | |
201 | * @sma: semaphore array | |
202 | * | |
203 | * The function unmerges the wait queues if complex_count is 0. | |
204 | * It must be called prior to dropping the global semaphore array lock. | |
205 | */ | |
206 | static void unmerge_queues(struct sem_array *sma) | |
207 | { | |
208 | struct sem_queue *q, *tq; | |
209 | ||
210 | /* complex operations still around? */ | |
211 | if (sma->complex_count) | |
212 | return; | |
213 | /* | |
214 | * We will switch back to simple mode. | |
215 | * Move all pending operation back into the per-semaphore | |
216 | * queues. | |
217 | */ | |
218 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { | |
219 | struct sem *curr; | |
220 | curr = &sma->sem_base[q->sops[0].sem_num]; | |
221 | ||
222 | list_add_tail(&q->list, &curr->pending_alter); | |
223 | } | |
224 | INIT_LIST_HEAD(&sma->pending_alter); | |
225 | } | |
226 | ||
227 | /** | |
228 | * merge_queues - Merge single semop queues into global queue | |
229 | * @sma: semaphore array | |
230 | * | |
231 | * This function merges all per-semaphore queues into the global queue. | |
232 | * It is necessary to achieve FIFO ordering for the pending single-sop | |
233 | * operations when a multi-semop operation must sleep. | |
234 | * Only the alter operations must be moved, the const operations can stay. | |
235 | */ | |
236 | static void merge_queues(struct sem_array *sma) | |
237 | { | |
238 | int i; | |
239 | for (i = 0; i < sma->sem_nsems; i++) { | |
240 | struct sem *sem = sma->sem_base + i; | |
241 | ||
242 | list_splice_init(&sem->pending_alter, &sma->pending_alter); | |
243 | } | |
244 | } | |
245 | ||
e84ca333 DB |
246 | static void sem_rcu_free(struct rcu_head *head) |
247 | { | |
248 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); | |
249 | struct sem_array *sma = ipc_rcu_to_struct(p); | |
250 | ||
251 | security_sem_free(sma); | |
252 | ipc_rcu_free(head); | |
253 | } | |
254 | ||
30e5bc30 MS |
255 | /* |
256 | * spin_unlock_wait() and !spin_is_locked() are not memory barriers, they | |
257 | * are only control barriers. | |
258 | * The code must pair with spin_unlock(&sem->lock) or | |
259 | * spin_unlock(&sem_perm.lock), thus just the control barrier is insufficient. | |
260 | * | |
261 | * smp_rmb() is sufficient, as writes cannot pass the control barrier. | |
262 | */ | |
263 | #define ipc_smp_acquire__after_spin_is_unlocked() smp_rmb() | |
264 | ||
184076a9 MS |
265 | /* |
266 | * Wait until all currently ongoing simple ops have completed. | |
267 | * Caller must own sem_perm.lock. | |
268 | * New simple ops cannot start, because simple ops first check | |
269 | * that sem_perm.lock is free. | |
270 | */ | |
271 | static void sem_wait_array(struct sem_array *sma) | |
272 | { | |
273 | int i; | |
274 | struct sem *sem; | |
275 | ||
276 | for (i = 0; i < sma->sem_nsems; i++) { | |
277 | sem = sma->sem_base + i; | |
278 | spin_unlock_wait(&sem->lock); | |
279 | } | |
30e5bc30 | 280 | ipc_smp_acquire__after_spin_is_unlocked(); |
184076a9 MS |
281 | } |
282 | ||
6062a8dc RR |
283 | /* |
284 | * If the request contains only one semaphore operation, and there are | |
285 | * no complex transactions pending, lock only the semaphore involved. | |
286 | * Otherwise, lock the entire semaphore array, since we either have | |
287 | * multiple semaphores in our own semops, or we need to look at | |
288 | * semaphores from other pending complex operations. | |
6062a8dc RR |
289 | */ |
290 | static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, | |
291 | int nsops) | |
292 | { | |
184076a9 | 293 | struct sem *sem; |
6062a8dc | 294 | |
184076a9 MS |
295 | if (nsops != 1) { |
296 | /* Complex operation - acquire a full lock */ | |
297 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 298 | |
184076a9 MS |
299 | /* And wait until all simple ops that are processed |
300 | * right now have dropped their locks. | |
6062a8dc | 301 | */ |
184076a9 MS |
302 | sem_wait_array(sma); |
303 | return -1; | |
304 | } | |
305 | ||
306 | /* | |
307 | * Only one semaphore affected - try to optimize locking. | |
308 | * The rules are: | |
309 | * - optimized locking is possible if no complex operation | |
310 | * is either enqueued or processed right now. | |
311 | * - The test for enqueued complex ops is simple: | |
312 | * sma->complex_count != 0 | |
313 | * - Testing for complex ops that are processed right now is | |
314 | * a bit more difficult. Complex ops acquire the full lock | |
315 | * and first wait that the running simple ops have completed. | |
316 | * (see above) | |
317 | * Thus: If we own a simple lock and the global lock is free | |
318 | * and complex_count is now 0, then it will stay 0 and | |
319 | * thus just locking sem->lock is sufficient. | |
320 | */ | |
321 | sem = sma->sem_base + sops->sem_num; | |
6062a8dc | 322 | |
184076a9 | 323 | if (sma->complex_count == 0) { |
6062a8dc | 324 | /* |
184076a9 MS |
325 | * It appears that no complex operation is around. |
326 | * Acquire the per-semaphore lock. | |
6062a8dc | 327 | */ |
184076a9 MS |
328 | spin_lock(&sem->lock); |
329 | ||
330 | /* Then check that the global lock is free */ | |
331 | if (!spin_is_locked(&sma->sem_perm.lock)) { | |
30e5bc30 MS |
332 | /* |
333 | * We need a memory barrier with acquire semantics, | |
334 | * otherwise we can race with another thread that does: | |
335 | * complex_count++; | |
336 | * spin_unlock(sem_perm.lock); | |
337 | */ | |
338 | ipc_smp_acquire__after_spin_is_unlocked(); | |
184076a9 MS |
339 | |
340 | /* Now repeat the test of complex_count: | |
341 | * It can't change anymore until we drop sem->lock. | |
342 | * Thus: if is now 0, then it will stay 0. | |
343 | */ | |
344 | if (sma->complex_count == 0) { | |
345 | /* fast path successful! */ | |
346 | return sops->sem_num; | |
347 | } | |
6062a8dc | 348 | } |
184076a9 MS |
349 | spin_unlock(&sem->lock); |
350 | } | |
351 | ||
352 | /* slow path: acquire the full lock */ | |
353 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 354 | |
184076a9 MS |
355 | if (sma->complex_count == 0) { |
356 | /* False alarm: | |
357 | * There is no complex operation, thus we can switch | |
358 | * back to the fast path. | |
359 | */ | |
360 | spin_lock(&sem->lock); | |
361 | ipc_unlock_object(&sma->sem_perm); | |
362 | return sops->sem_num; | |
6062a8dc | 363 | } else { |
184076a9 MS |
364 | /* Not a false alarm, thus complete the sequence for a |
365 | * full lock. | |
6062a8dc | 366 | */ |
184076a9 MS |
367 | sem_wait_array(sma); |
368 | return -1; | |
6062a8dc | 369 | } |
6062a8dc RR |
370 | } |
371 | ||
372 | static inline void sem_unlock(struct sem_array *sma, int locknum) | |
373 | { | |
374 | if (locknum == -1) { | |
e5639c52 | 375 | unmerge_queues(sma); |
115d40db | 376 | ipc_unlock_object(&sma->sem_perm); |
6062a8dc RR |
377 | } else { |
378 | struct sem *sem = sma->sem_base + locknum; | |
379 | spin_unlock(&sem->lock); | |
380 | } | |
6062a8dc RR |
381 | } |
382 | ||
3e148c79 | 383 | /* |
33b74669 | 384 | * sem_lock_(check_) routines are called in the paths where the rwsem |
3e148c79 | 385 | * is not held. |
321310ce LT |
386 | * |
387 | * The caller holds the RCU read lock. | |
3e148c79 | 388 | */ |
6062a8dc RR |
389 | static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, |
390 | int id, struct sembuf *sops, int nsops, int *locknum) | |
023a5355 | 391 | { |
c460b662 RR |
392 | struct kern_ipc_perm *ipcp; |
393 | struct sem_array *sma; | |
03f02c76 | 394 | |
c460b662 | 395 | ipcp = ipc_obtain_object(&sem_ids(ns), id); |
321310ce LT |
396 | if (IS_ERR(ipcp)) |
397 | return ERR_CAST(ipcp); | |
b1ed88b4 | 398 | |
6062a8dc RR |
399 | sma = container_of(ipcp, struct sem_array, sem_perm); |
400 | *locknum = sem_lock(sma, sops, nsops); | |
c460b662 RR |
401 | |
402 | /* ipc_rmid() may have already freed the ID while sem_lock | |
403 | * was spinning: verify that the structure is still valid | |
404 | */ | |
405 | if (!ipcp->deleted) | |
406 | return container_of(ipcp, struct sem_array, sem_perm); | |
407 | ||
6062a8dc | 408 | sem_unlock(sma, *locknum); |
321310ce | 409 | return ERR_PTR(-EINVAL); |
023a5355 ND |
410 | } |
411 | ||
16df3674 DB |
412 | static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id) |
413 | { | |
414 | struct kern_ipc_perm *ipcp = ipc_obtain_object(&sem_ids(ns), id); | |
415 | ||
416 | if (IS_ERR(ipcp)) | |
417 | return ERR_CAST(ipcp); | |
418 | ||
419 | return container_of(ipcp, struct sem_array, sem_perm); | |
420 | } | |
421 | ||
16df3674 DB |
422 | static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns, |
423 | int id) | |
424 | { | |
425 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id); | |
426 | ||
427 | if (IS_ERR(ipcp)) | |
428 | return ERR_CAST(ipcp); | |
b1ed88b4 | 429 | |
03f02c76 | 430 | return container_of(ipcp, struct sem_array, sem_perm); |
023a5355 ND |
431 | } |
432 | ||
6ff37972 PP |
433 | static inline void sem_lock_and_putref(struct sem_array *sma) |
434 | { | |
6062a8dc | 435 | sem_lock(sma, NULL, -1); |
e84ca333 | 436 | ipc_rcu_putref(sma, ipc_rcu_free); |
6ff37972 PP |
437 | } |
438 | ||
7ca7e564 ND |
439 | static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) |
440 | { | |
441 | ipc_rmid(&sem_ids(ns), &s->sem_perm); | |
442 | } | |
443 | ||
1da177e4 LT |
444 | /* |
445 | * Lockless wakeup algorithm: | |
446 | * Without the check/retry algorithm a lockless wakeup is possible: | |
447 | * - queue.status is initialized to -EINTR before blocking. | |
448 | * - wakeup is performed by | |
ab63bc97 | 449 | * * unlinking the queue entry from the pending list |
1da177e4 LT |
450 | * * setting queue.status to IN_WAKEUP |
451 | * This is the notification for the blocked thread that a | |
452 | * result value is imminent. | |
453 | * * call wake_up_process | |
454 | * * set queue.status to the final value. | |
455 | * - the previously blocked thread checks queue.status: | |
456 | * * if it's IN_WAKEUP, then it must wait until the value changes | |
457 | * * if it's not -EINTR, then the operation was completed by | |
458 | * update_queue. semtimedop can return queue.status without | |
5f921ae9 | 459 | * performing any operation on the sem array. |
1da177e4 LT |
460 | * * otherwise it must acquire the spinlock and check what's up. |
461 | * | |
462 | * The two-stage algorithm is necessary to protect against the following | |
463 | * races: | |
464 | * - if queue.status is set after wake_up_process, then the woken up idle | |
465 | * thread could race forward and try (and fail) to acquire sma->lock | |
466 | * before update_queue had a chance to set queue.status | |
467 | * - if queue.status is written before wake_up_process and if the | |
468 | * blocked process is woken up by a signal between writing | |
469 | * queue.status and the wake_up_process, then the woken up | |
470 | * process could return from semtimedop and die by calling | |
471 | * sys_exit before wake_up_process is called. Then wake_up_process | |
472 | * will oops, because the task structure is already invalid. | |
473 | * (yes, this happened on s390 with sysv msg). | |
474 | * | |
475 | */ | |
476 | #define IN_WAKEUP 1 | |
477 | ||
f4566f04 ND |
478 | /** |
479 | * newary - Create a new semaphore set | |
480 | * @ns: namespace | |
481 | * @params: ptr to the structure that contains key, semflg and nsems | |
482 | * | |
33b74669 | 483 | * Called with sem_ids.rwsem held (as a writer) |
f4566f04 ND |
484 | */ |
485 | ||
7748dbfa | 486 | static int newary(struct ipc_namespace *ns, struct ipc_params *params) |
1da177e4 LT |
487 | { |
488 | int id; | |
489 | int retval; | |
490 | struct sem_array *sma; | |
491 | int size; | |
7748dbfa ND |
492 | key_t key = params->key; |
493 | int nsems = params->u.nsems; | |
494 | int semflg = params->flg; | |
b97e820f | 495 | int i; |
1da177e4 LT |
496 | |
497 | if (!nsems) | |
498 | return -EINVAL; | |
e3893534 | 499 | if (ns->used_sems + nsems > ns->sc_semmns) |
1da177e4 LT |
500 | return -ENOSPC; |
501 | ||
502 | size = sizeof (*sma) + nsems * sizeof (struct sem); | |
503 | sma = ipc_rcu_alloc(size); | |
504 | if (!sma) { | |
505 | return -ENOMEM; | |
506 | } | |
507 | memset (sma, 0, size); | |
508 | ||
509 | sma->sem_perm.mode = (semflg & S_IRWXUGO); | |
510 | sma->sem_perm.key = key; | |
511 | ||
512 | sma->sem_perm.security = NULL; | |
513 | retval = security_sem_alloc(sma); | |
514 | if (retval) { | |
e84ca333 | 515 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
516 | return retval; |
517 | } | |
518 | ||
e3893534 | 519 | id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); |
283bb7fa | 520 | if (id < 0) { |
e84ca333 | 521 | ipc_rcu_putref(sma, sem_rcu_free); |
283bb7fa | 522 | return id; |
1da177e4 | 523 | } |
e3893534 | 524 | ns->used_sems += nsems; |
1da177e4 LT |
525 | |
526 | sma->sem_base = (struct sem *) &sma[1]; | |
b97e820f | 527 | |
6062a8dc | 528 | for (i = 0; i < nsems; i++) { |
ab63bc97 MS |
529 | INIT_LIST_HEAD(&sma->sem_base[i].pending_alter); |
530 | INIT_LIST_HEAD(&sma->sem_base[i].pending_const); | |
6062a8dc RR |
531 | spin_lock_init(&sma->sem_base[i].lock); |
532 | } | |
b97e820f MS |
533 | |
534 | sma->complex_count = 0; | |
ab63bc97 MS |
535 | INIT_LIST_HEAD(&sma->pending_alter); |
536 | INIT_LIST_HEAD(&sma->pending_const); | |
4daa28f6 | 537 | INIT_LIST_HEAD(&sma->list_id); |
1da177e4 LT |
538 | sma->sem_nsems = nsems; |
539 | sma->sem_ctime = get_seconds(); | |
6062a8dc | 540 | sem_unlock(sma, -1); |
6d49dab8 | 541 | rcu_read_unlock(); |
1da177e4 | 542 | |
7ca7e564 | 543 | return sma->sem_perm.id; |
1da177e4 LT |
544 | } |
545 | ||
7748dbfa | 546 | |
f4566f04 | 547 | /* |
33b74669 | 548 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 549 | */ |
03f02c76 | 550 | static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) |
7748dbfa | 551 | { |
03f02c76 ND |
552 | struct sem_array *sma; |
553 | ||
554 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
555 | return security_sem_associate(sma, semflg); | |
7748dbfa ND |
556 | } |
557 | ||
f4566f04 | 558 | /* |
33b74669 | 559 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 560 | */ |
03f02c76 ND |
561 | static inline int sem_more_checks(struct kern_ipc_perm *ipcp, |
562 | struct ipc_params *params) | |
7748dbfa | 563 | { |
03f02c76 ND |
564 | struct sem_array *sma; |
565 | ||
566 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
567 | if (params->u.nsems > sma->sem_nsems) | |
7748dbfa ND |
568 | return -EINVAL; |
569 | ||
570 | return 0; | |
571 | } | |
572 | ||
d5460c99 | 573 | SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) |
1da177e4 | 574 | { |
e3893534 | 575 | struct ipc_namespace *ns; |
7748dbfa ND |
576 | struct ipc_ops sem_ops; |
577 | struct ipc_params sem_params; | |
e3893534 KK |
578 | |
579 | ns = current->nsproxy->ipc_ns; | |
1da177e4 | 580 | |
e3893534 | 581 | if (nsems < 0 || nsems > ns->sc_semmsl) |
1da177e4 | 582 | return -EINVAL; |
7ca7e564 | 583 | |
7748dbfa ND |
584 | sem_ops.getnew = newary; |
585 | sem_ops.associate = sem_security; | |
586 | sem_ops.more_checks = sem_more_checks; | |
587 | ||
588 | sem_params.key = key; | |
589 | sem_params.flg = semflg; | |
590 | sem_params.u.nsems = nsems; | |
1da177e4 | 591 | |
7748dbfa | 592 | return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); |
1da177e4 LT |
593 | } |
594 | ||
b56e88e2 MS |
595 | /** perform_atomic_semop - Perform (if possible) a semaphore operation |
596 | * @sma: semaphore array | |
597 | * @sops: array with operations that should be checked | |
598 | * @nsems: number of sops | |
599 | * @un: undo array | |
600 | * @pid: pid that did the change | |
601 | * | |
602 | * Returns 0 if the operation was possible. | |
603 | * Returns 1 if the operation is impossible, the caller must sleep. | |
604 | * Negative values are error codes. | |
1da177e4 LT |
605 | */ |
606 | ||
b56e88e2 | 607 | static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops, |
1da177e4 LT |
608 | int nsops, struct sem_undo *un, int pid) |
609 | { | |
610 | int result, sem_op; | |
611 | struct sembuf *sop; | |
612 | struct sem * curr; | |
613 | ||
614 | for (sop = sops; sop < sops + nsops; sop++) { | |
615 | curr = sma->sem_base + sop->sem_num; | |
616 | sem_op = sop->sem_op; | |
617 | result = curr->semval; | |
618 | ||
619 | if (!sem_op && result) | |
620 | goto would_block; | |
621 | ||
622 | result += sem_op; | |
623 | if (result < 0) | |
624 | goto would_block; | |
625 | if (result > SEMVMX) | |
626 | goto out_of_range; | |
627 | if (sop->sem_flg & SEM_UNDO) { | |
628 | int undo = un->semadj[sop->sem_num] - sem_op; | |
629 | /* | |
630 | * Exceeding the undo range is an error. | |
631 | */ | |
632 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) | |
633 | goto out_of_range; | |
634 | } | |
635 | curr->semval = result; | |
636 | } | |
637 | ||
638 | sop--; | |
639 | while (sop >= sops) { | |
640 | sma->sem_base[sop->sem_num].sempid = pid; | |
641 | if (sop->sem_flg & SEM_UNDO) | |
642 | un->semadj[sop->sem_num] -= sop->sem_op; | |
643 | sop--; | |
644 | } | |
645 | ||
1da177e4 LT |
646 | return 0; |
647 | ||
648 | out_of_range: | |
649 | result = -ERANGE; | |
650 | goto undo; | |
651 | ||
652 | would_block: | |
653 | if (sop->sem_flg & IPC_NOWAIT) | |
654 | result = -EAGAIN; | |
655 | else | |
656 | result = 1; | |
657 | ||
658 | undo: | |
659 | sop--; | |
660 | while (sop >= sops) { | |
661 | sma->sem_base[sop->sem_num].semval -= sop->sem_op; | |
662 | sop--; | |
663 | } | |
664 | ||
665 | return result; | |
666 | } | |
667 | ||
0a2b9d4c MS |
668 | /** wake_up_sem_queue_prepare(q, error): Prepare wake-up |
669 | * @q: queue entry that must be signaled | |
670 | * @error: Error value for the signal | |
671 | * | |
672 | * Prepare the wake-up of the queue entry q. | |
d4212093 | 673 | */ |
0a2b9d4c MS |
674 | static void wake_up_sem_queue_prepare(struct list_head *pt, |
675 | struct sem_queue *q, int error) | |
d4212093 | 676 | { |
0a2b9d4c MS |
677 | if (list_empty(pt)) { |
678 | /* | |
679 | * Hold preempt off so that we don't get preempted and have the | |
680 | * wakee busy-wait until we're scheduled back on. | |
681 | */ | |
682 | preempt_disable(); | |
683 | } | |
d4212093 | 684 | q->status = IN_WAKEUP; |
0a2b9d4c MS |
685 | q->pid = error; |
686 | ||
9f1bc2c9 | 687 | list_add_tail(&q->list, pt); |
0a2b9d4c MS |
688 | } |
689 | ||
690 | /** | |
691 | * wake_up_sem_queue_do(pt) - do the actual wake-up | |
692 | * @pt: list of tasks to be woken up | |
693 | * | |
694 | * Do the actual wake-up. | |
695 | * The function is called without any locks held, thus the semaphore array | |
696 | * could be destroyed already and the tasks can disappear as soon as the | |
697 | * status is set to the actual return code. | |
698 | */ | |
699 | static void wake_up_sem_queue_do(struct list_head *pt) | |
700 | { | |
701 | struct sem_queue *q, *t; | |
702 | int did_something; | |
703 | ||
704 | did_something = !list_empty(pt); | |
9f1bc2c9 | 705 | list_for_each_entry_safe(q, t, pt, list) { |
0a2b9d4c MS |
706 | wake_up_process(q->sleeper); |
707 | /* q can disappear immediately after writing q->status. */ | |
708 | smp_wmb(); | |
709 | q->status = q->pid; | |
710 | } | |
711 | if (did_something) | |
712 | preempt_enable(); | |
d4212093 NP |
713 | } |
714 | ||
b97e820f MS |
715 | static void unlink_queue(struct sem_array *sma, struct sem_queue *q) |
716 | { | |
717 | list_del(&q->list); | |
9f1bc2c9 | 718 | if (q->nsops > 1) |
b97e820f MS |
719 | sma->complex_count--; |
720 | } | |
721 | ||
fd5db422 MS |
722 | /** check_restart(sma, q) |
723 | * @sma: semaphore array | |
724 | * @q: the operation that just completed | |
725 | * | |
726 | * update_queue is O(N^2) when it restarts scanning the whole queue of | |
727 | * waiting operations. Therefore this function checks if the restart is | |
728 | * really necessary. It is called after a previously waiting operation | |
ab63bc97 MS |
729 | * modified the array. |
730 | * Note that wait-for-zero operations are handled without restart. | |
fd5db422 MS |
731 | */ |
732 | static int check_restart(struct sem_array *sma, struct sem_queue *q) | |
733 | { | |
ab63bc97 MS |
734 | /* pending complex alter operations are too difficult to analyse */ |
735 | if (!list_empty(&sma->pending_alter)) | |
fd5db422 MS |
736 | return 1; |
737 | ||
738 | /* we were a sleeping complex operation. Too difficult */ | |
739 | if (q->nsops > 1) | |
740 | return 1; | |
741 | ||
ab63bc97 MS |
742 | /* It is impossible that someone waits for the new value: |
743 | * - complex operations always restart. | |
744 | * - wait-for-zero are handled seperately. | |
745 | * - q is a previously sleeping simple operation that | |
746 | * altered the array. It must be a decrement, because | |
747 | * simple increments never sleep. | |
748 | * - If there are older (higher priority) decrements | |
749 | * in the queue, then they have observed the original | |
750 | * semval value and couldn't proceed. The operation | |
751 | * decremented to value - thus they won't proceed either. | |
752 | */ | |
753 | return 0; | |
754 | } | |
fd5db422 | 755 | |
ab63bc97 MS |
756 | /** |
757 | * wake_const_ops(sma, semnum, pt) - Wake up non-alter tasks | |
758 | * @sma: semaphore array. | |
759 | * @semnum: semaphore that was modified. | |
760 | * @pt: list head for the tasks that must be woken up. | |
761 | * | |
762 | * wake_const_ops must be called after a semaphore in a semaphore array | |
763 | * was set to 0. If complex const operations are pending, wake_const_ops must | |
764 | * be called with semnum = -1, as well as with the number of each modified | |
765 | * semaphore. | |
766 | * The tasks that must be woken up are added to @pt. The return code | |
767 | * is stored in q->pid. | |
768 | * The function returns 1 if at least one operation was completed successfully. | |
769 | */ | |
770 | static int wake_const_ops(struct sem_array *sma, int semnum, | |
771 | struct list_head *pt) | |
772 | { | |
773 | struct sem_queue *q; | |
774 | struct list_head *walk; | |
775 | struct list_head *pending_list; | |
776 | int semop_completed = 0; | |
777 | ||
778 | if (semnum == -1) | |
779 | pending_list = &sma->pending_const; | |
780 | else | |
781 | pending_list = &sma->sem_base[semnum].pending_const; | |
fd5db422 | 782 | |
ab63bc97 MS |
783 | walk = pending_list->next; |
784 | while (walk != pending_list) { | |
785 | int error; | |
786 | ||
787 | q = container_of(walk, struct sem_queue, list); | |
788 | walk = walk->next; | |
789 | ||
b56e88e2 MS |
790 | error = perform_atomic_semop(sma, q->sops, q->nsops, |
791 | q->undo, q->pid); | |
ab63bc97 MS |
792 | |
793 | if (error <= 0) { | |
794 | /* operation completed, remove from queue & wakeup */ | |
795 | ||
796 | unlink_queue(sma, q); | |
797 | ||
798 | wake_up_sem_queue_prepare(pt, q, error); | |
799 | if (error == 0) | |
800 | semop_completed = 1; | |
801 | } | |
802 | } | |
803 | return semop_completed; | |
804 | } | |
805 | ||
806 | /** | |
807 | * do_smart_wakeup_zero(sma, sops, nsops, pt) - wakeup all wait for zero tasks | |
808 | * @sma: semaphore array | |
809 | * @sops: operations that were performed | |
810 | * @nsops: number of operations | |
811 | * @pt: list head of the tasks that must be woken up. | |
812 | * | |
813 | * do_smart_wakeup_zero() checks all required queue for wait-for-zero | |
814 | * operations, based on the actual changes that were performed on the | |
815 | * semaphore array. | |
816 | * The function returns 1 if at least one operation was completed successfully. | |
817 | */ | |
818 | static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, | |
819 | int nsops, struct list_head *pt) | |
820 | { | |
821 | int i; | |
822 | int semop_completed = 0; | |
823 | int got_zero = 0; | |
824 | ||
825 | /* first: the per-semaphore queues, if known */ | |
826 | if (sops) { | |
827 | for (i = 0; i < nsops; i++) { | |
828 | int num = sops[i].sem_num; | |
829 | ||
830 | if (sma->sem_base[num].semval == 0) { | |
831 | got_zero = 1; | |
832 | semop_completed |= wake_const_ops(sma, num, pt); | |
833 | } | |
834 | } | |
835 | } else { | |
836 | /* | |
837 | * No sops means modified semaphores not known. | |
838 | * Assume all were changed. | |
fd5db422 | 839 | */ |
ab63bc97 MS |
840 | for (i = 0; i < sma->sem_nsems; i++) { |
841 | if (sma->sem_base[i].semval == 0) { | |
842 | got_zero = 1; | |
843 | semop_completed |= wake_const_ops(sma, i, pt); | |
844 | } | |
845 | } | |
fd5db422 MS |
846 | } |
847 | /* | |
ab63bc97 MS |
848 | * If one of the modified semaphores got 0, |
849 | * then check the global queue, too. | |
fd5db422 | 850 | */ |
ab63bc97 MS |
851 | if (got_zero) |
852 | semop_completed |= wake_const_ops(sma, -1, pt); | |
fd5db422 | 853 | |
ab63bc97 | 854 | return semop_completed; |
fd5db422 MS |
855 | } |
856 | ||
636c6be8 MS |
857 | |
858 | /** | |
859 | * update_queue(sma, semnum): Look for tasks that can be completed. | |
860 | * @sma: semaphore array. | |
861 | * @semnum: semaphore that was modified. | |
0a2b9d4c | 862 | * @pt: list head for the tasks that must be woken up. |
636c6be8 MS |
863 | * |
864 | * update_queue must be called after a semaphore in a semaphore array | |
9f1bc2c9 RR |
865 | * was modified. If multiple semaphores were modified, update_queue must |
866 | * be called with semnum = -1, as well as with the number of each modified | |
867 | * semaphore. | |
0a2b9d4c MS |
868 | * The tasks that must be woken up are added to @pt. The return code |
869 | * is stored in q->pid. | |
ab63bc97 MS |
870 | * The function internally checks if const operations can now succeed. |
871 | * | |
0a2b9d4c | 872 | * The function return 1 if at least one semop was completed successfully. |
1da177e4 | 873 | */ |
0a2b9d4c | 874 | static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt) |
1da177e4 | 875 | { |
636c6be8 MS |
876 | struct sem_queue *q; |
877 | struct list_head *walk; | |
878 | struct list_head *pending_list; | |
0a2b9d4c | 879 | int semop_completed = 0; |
636c6be8 | 880 | |
9f1bc2c9 | 881 | if (semnum == -1) |
ab63bc97 | 882 | pending_list = &sma->pending_alter; |
9f1bc2c9 | 883 | else |
ab63bc97 | 884 | pending_list = &sma->sem_base[semnum].pending_alter; |
9cad200c NP |
885 | |
886 | again: | |
636c6be8 MS |
887 | walk = pending_list->next; |
888 | while (walk != pending_list) { | |
fd5db422 | 889 | int error, restart; |
636c6be8 | 890 | |
9f1bc2c9 | 891 | q = container_of(walk, struct sem_queue, list); |
636c6be8 | 892 | walk = walk->next; |
1da177e4 | 893 | |
d987f8b2 MS |
894 | /* If we are scanning the single sop, per-semaphore list of |
895 | * one semaphore and that semaphore is 0, then it is not | |
ab63bc97 | 896 | * necessary to scan further: simple increments |
d987f8b2 MS |
897 | * that affect only one entry succeed immediately and cannot |
898 | * be in the per semaphore pending queue, and decrements | |
899 | * cannot be successful if the value is already 0. | |
900 | */ | |
ab63bc97 | 901 | if (semnum != -1 && sma->sem_base[semnum].semval == 0) |
d987f8b2 MS |
902 | break; |
903 | ||
b56e88e2 | 904 | error = perform_atomic_semop(sma, q->sops, q->nsops, |
1da177e4 LT |
905 | q->undo, q->pid); |
906 | ||
907 | /* Does q->sleeper still need to sleep? */ | |
9cad200c NP |
908 | if (error > 0) |
909 | continue; | |
910 | ||
b97e820f | 911 | unlink_queue(sma, q); |
9cad200c | 912 | |
0a2b9d4c | 913 | if (error) { |
fd5db422 | 914 | restart = 0; |
0a2b9d4c MS |
915 | } else { |
916 | semop_completed = 1; | |
ab63bc97 | 917 | do_smart_wakeup_zero(sma, q->sops, q->nsops, pt); |
fd5db422 | 918 | restart = check_restart(sma, q); |
0a2b9d4c | 919 | } |
fd5db422 | 920 | |
0a2b9d4c | 921 | wake_up_sem_queue_prepare(pt, q, error); |
fd5db422 | 922 | if (restart) |
9cad200c | 923 | goto again; |
1da177e4 | 924 | } |
0a2b9d4c | 925 | return semop_completed; |
1da177e4 LT |
926 | } |
927 | ||
e556ea01 MS |
928 | /** |
929 | * set_semotime(sma, sops) - set sem_otime | |
930 | * @sma: semaphore array | |
931 | * @sops: operations that modified the array, may be NULL | |
932 | * | |
933 | * sem_otime is replicated to avoid cache line trashing. | |
934 | * This function sets one instance to the current time. | |
935 | */ | |
936 | static void set_semotime(struct sem_array *sma, struct sembuf *sops) | |
937 | { | |
938 | if (sops == NULL) { | |
939 | sma->sem_base[0].sem_otime = get_seconds(); | |
940 | } else { | |
941 | sma->sem_base[sops[0].sem_num].sem_otime = | |
942 | get_seconds(); | |
943 | } | |
944 | } | |
945 | ||
0a2b9d4c MS |
946 | /** |
947 | * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue | |
fd5db422 MS |
948 | * @sma: semaphore array |
949 | * @sops: operations that were performed | |
950 | * @nsops: number of operations | |
0a2b9d4c MS |
951 | * @otime: force setting otime |
952 | * @pt: list head of the tasks that must be woken up. | |
fd5db422 | 953 | * |
ab63bc97 MS |
954 | * do_smart_update() does the required calls to update_queue and wakeup_zero, |
955 | * based on the actual changes that were performed on the semaphore array. | |
0a2b9d4c MS |
956 | * Note that the function does not do the actual wake-up: the caller is |
957 | * responsible for calling wake_up_sem_queue_do(@pt). | |
958 | * It is safe to perform this call after dropping all locks. | |
fd5db422 | 959 | */ |
0a2b9d4c MS |
960 | static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops, |
961 | int otime, struct list_head *pt) | |
fd5db422 MS |
962 | { |
963 | int i; | |
964 | ||
ab63bc97 MS |
965 | otime |= do_smart_wakeup_zero(sma, sops, nsops, pt); |
966 | ||
e5639c52 MS |
967 | if (!list_empty(&sma->pending_alter)) { |
968 | /* semaphore array uses the global queue - just process it. */ | |
969 | otime |= update_queue(sma, -1, pt); | |
970 | } else { | |
971 | if (!sops) { | |
972 | /* | |
973 | * No sops, thus the modified semaphores are not | |
974 | * known. Check all. | |
975 | */ | |
976 | for (i = 0; i < sma->sem_nsems; i++) | |
977 | otime |= update_queue(sma, i, pt); | |
978 | } else { | |
979 | /* | |
980 | * Check the semaphores that were increased: | |
981 | * - No complex ops, thus all sleeping ops are | |
982 | * decrease. | |
983 | * - if we decreased the value, then any sleeping | |
984 | * semaphore ops wont be able to run: If the | |
985 | * previous value was too small, then the new | |
986 | * value will be too small, too. | |
987 | */ | |
988 | for (i = 0; i < nsops; i++) { | |
989 | if (sops[i].sem_op > 0) { | |
990 | otime |= update_queue(sma, | |
991 | sops[i].sem_num, pt); | |
992 | } | |
ab465df9 | 993 | } |
9f1bc2c9 | 994 | } |
fd5db422 | 995 | } |
e556ea01 MS |
996 | if (otime) |
997 | set_semotime(sma, sops); | |
fd5db422 MS |
998 | } |
999 | ||
1da177e4 LT |
1000 | /* The following counts are associated to each semaphore: |
1001 | * semncnt number of tasks waiting on semval being nonzero | |
1002 | * semzcnt number of tasks waiting on semval being zero | |
1003 | * This model assumes that a task waits on exactly one semaphore. | |
1004 | * Since semaphore operations are to be performed atomically, tasks actually | |
1005 | * wait on a whole sequence of semaphores simultaneously. | |
1006 | * The counts we return here are a rough approximation, but still | |
1007 | * warrant that semncnt+semzcnt>0 if the task is on the pending queue. | |
1008 | */ | |
1009 | static int count_semncnt (struct sem_array * sma, ushort semnum) | |
1010 | { | |
1011 | int semncnt; | |
1012 | struct sem_queue * q; | |
1013 | ||
1014 | semncnt = 0; | |
ab63bc97 | 1015 | list_for_each_entry(q, &sma->sem_base[semnum].pending_alter, list) { |
de2657f9 RR |
1016 | struct sembuf * sops = q->sops; |
1017 | BUG_ON(sops->sem_num != semnum); | |
1018 | if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT)) | |
1019 | semncnt++; | |
1020 | } | |
1021 | ||
ab63bc97 | 1022 | list_for_each_entry(q, &sma->pending_alter, list) { |
1da177e4 LT |
1023 | struct sembuf * sops = q->sops; |
1024 | int nsops = q->nsops; | |
1025 | int i; | |
1026 | for (i = 0; i < nsops; i++) | |
1027 | if (sops[i].sem_num == semnum | |
1028 | && (sops[i].sem_op < 0) | |
1029 | && !(sops[i].sem_flg & IPC_NOWAIT)) | |
1030 | semncnt++; | |
1031 | } | |
1032 | return semncnt; | |
1033 | } | |
a1193f8e | 1034 | |
1da177e4 LT |
1035 | static int count_semzcnt (struct sem_array * sma, ushort semnum) |
1036 | { | |
1037 | int semzcnt; | |
1038 | struct sem_queue * q; | |
1039 | ||
1040 | semzcnt = 0; | |
ab63bc97 | 1041 | list_for_each_entry(q, &sma->sem_base[semnum].pending_const, list) { |
ebc2e5e6 RR |
1042 | struct sembuf * sops = q->sops; |
1043 | BUG_ON(sops->sem_num != semnum); | |
1044 | if ((sops->sem_op == 0) && !(sops->sem_flg & IPC_NOWAIT)) | |
1045 | semzcnt++; | |
1046 | } | |
1047 | ||
ab63bc97 | 1048 | list_for_each_entry(q, &sma->pending_const, list) { |
1da177e4 LT |
1049 | struct sembuf * sops = q->sops; |
1050 | int nsops = q->nsops; | |
1051 | int i; | |
1052 | for (i = 0; i < nsops; i++) | |
1053 | if (sops[i].sem_num == semnum | |
1054 | && (sops[i].sem_op == 0) | |
1055 | && !(sops[i].sem_flg & IPC_NOWAIT)) | |
1056 | semzcnt++; | |
1057 | } | |
1058 | return semzcnt; | |
1059 | } | |
1060 | ||
33b74669 DB |
1061 | /* Free a semaphore set. freeary() is called with sem_ids.rwsem locked |
1062 | * as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem | |
3e148c79 | 1063 | * remains locked on exit. |
1da177e4 | 1064 | */ |
01b8b07a | 1065 | static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
1da177e4 | 1066 | { |
380af1b3 MS |
1067 | struct sem_undo *un, *tu; |
1068 | struct sem_queue *q, *tq; | |
01b8b07a | 1069 | struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
0a2b9d4c | 1070 | struct list_head tasks; |
9f1bc2c9 | 1071 | int i; |
1da177e4 | 1072 | |
380af1b3 | 1073 | /* Free the existing undo structures for this semaphore set. */ |
115d40db | 1074 | ipc_assert_locked_object(&sma->sem_perm); |
380af1b3 MS |
1075 | list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { |
1076 | list_del(&un->list_id); | |
1077 | spin_lock(&un->ulp->lock); | |
1da177e4 | 1078 | un->semid = -1; |
380af1b3 MS |
1079 | list_del_rcu(&un->list_proc); |
1080 | spin_unlock(&un->ulp->lock); | |
693a8b6e | 1081 | kfree_rcu(un, rcu); |
380af1b3 | 1082 | } |
1da177e4 LT |
1083 | |
1084 | /* Wake up all pending processes and let them fail with EIDRM. */ | |
0a2b9d4c | 1085 | INIT_LIST_HEAD(&tasks); |
ab63bc97 MS |
1086 | list_for_each_entry_safe(q, tq, &sma->pending_const, list) { |
1087 | unlink_queue(sma, q); | |
1088 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1089 | } | |
1090 | ||
1091 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { | |
b97e820f | 1092 | unlink_queue(sma, q); |
0a2b9d4c | 1093 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); |
1da177e4 | 1094 | } |
9f1bc2c9 RR |
1095 | for (i = 0; i < sma->sem_nsems; i++) { |
1096 | struct sem *sem = sma->sem_base + i; | |
ab63bc97 MS |
1097 | list_for_each_entry_safe(q, tq, &sem->pending_const, list) { |
1098 | unlink_queue(sma, q); | |
1099 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1100 | } | |
1101 | list_for_each_entry_safe(q, tq, &sem->pending_alter, list) { | |
9f1bc2c9 RR |
1102 | unlink_queue(sma, q); |
1103 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1104 | } | |
1105 | } | |
1da177e4 | 1106 | |
7ca7e564 ND |
1107 | /* Remove the semaphore set from the IDR */ |
1108 | sem_rmid(ns, sma); | |
6062a8dc | 1109 | sem_unlock(sma, -1); |
6d49dab8 | 1110 | rcu_read_unlock(); |
1da177e4 | 1111 | |
0a2b9d4c | 1112 | wake_up_sem_queue_do(&tasks); |
e3893534 | 1113 | ns->used_sems -= sma->sem_nsems; |
e84ca333 | 1114 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1115 | } |
1116 | ||
1117 | static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) | |
1118 | { | |
1119 | switch(version) { | |
1120 | case IPC_64: | |
1121 | return copy_to_user(buf, in, sizeof(*in)); | |
1122 | case IPC_OLD: | |
1123 | { | |
1124 | struct semid_ds out; | |
1125 | ||
982f7c2b DR |
1126 | memset(&out, 0, sizeof(out)); |
1127 | ||
1da177e4 LT |
1128 | ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm); |
1129 | ||
1130 | out.sem_otime = in->sem_otime; | |
1131 | out.sem_ctime = in->sem_ctime; | |
1132 | out.sem_nsems = in->sem_nsems; | |
1133 | ||
1134 | return copy_to_user(buf, &out, sizeof(out)); | |
1135 | } | |
1136 | default: | |
1137 | return -EINVAL; | |
1138 | } | |
1139 | } | |
1140 | ||
bf6830ad MS |
1141 | static time_t get_semotime(struct sem_array *sma) |
1142 | { | |
1143 | int i; | |
1144 | time_t res; | |
1145 | ||
1146 | res = sma->sem_base[0].sem_otime; | |
1147 | for (i = 1; i < sma->sem_nsems; i++) { | |
1148 | time_t to = sma->sem_base[i].sem_otime; | |
1149 | ||
1150 | if (to > res) | |
1151 | res = to; | |
1152 | } | |
1153 | return res; | |
1154 | } | |
1155 | ||
4b9fcb0e | 1156 | static int semctl_nolock(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1157 | int cmd, int version, void __user *p) |
1da177e4 | 1158 | { |
e5cc9c7b | 1159 | int err; |
1da177e4 LT |
1160 | struct sem_array *sma; |
1161 | ||
1162 | switch(cmd) { | |
1163 | case IPC_INFO: | |
1164 | case SEM_INFO: | |
1165 | { | |
1166 | struct seminfo seminfo; | |
1167 | int max_id; | |
1168 | ||
1169 | err = security_sem_semctl(NULL, cmd); | |
1170 | if (err) | |
1171 | return err; | |
1172 | ||
1173 | memset(&seminfo,0,sizeof(seminfo)); | |
e3893534 KK |
1174 | seminfo.semmni = ns->sc_semmni; |
1175 | seminfo.semmns = ns->sc_semmns; | |
1176 | seminfo.semmsl = ns->sc_semmsl; | |
1177 | seminfo.semopm = ns->sc_semopm; | |
1da177e4 LT |
1178 | seminfo.semvmx = SEMVMX; |
1179 | seminfo.semmnu = SEMMNU; | |
1180 | seminfo.semmap = SEMMAP; | |
1181 | seminfo.semume = SEMUME; | |
33b74669 | 1182 | down_read(&sem_ids(ns).rwsem); |
1da177e4 | 1183 | if (cmd == SEM_INFO) { |
e3893534 KK |
1184 | seminfo.semusz = sem_ids(ns).in_use; |
1185 | seminfo.semaem = ns->used_sems; | |
1da177e4 LT |
1186 | } else { |
1187 | seminfo.semusz = SEMUSZ; | |
1188 | seminfo.semaem = SEMAEM; | |
1189 | } | |
7ca7e564 | 1190 | max_id = ipc_get_maxid(&sem_ids(ns)); |
33b74669 | 1191 | up_read(&sem_ids(ns).rwsem); |
e1fd1f49 | 1192 | if (copy_to_user(p, &seminfo, sizeof(struct seminfo))) |
1da177e4 LT |
1193 | return -EFAULT; |
1194 | return (max_id < 0) ? 0: max_id; | |
1195 | } | |
4b9fcb0e | 1196 | case IPC_STAT: |
1da177e4 LT |
1197 | case SEM_STAT: |
1198 | { | |
1199 | struct semid64_ds tbuf; | |
16df3674 DB |
1200 | int id = 0; |
1201 | ||
1202 | memset(&tbuf, 0, sizeof(tbuf)); | |
1da177e4 | 1203 | |
941b0304 | 1204 | rcu_read_lock(); |
4b9fcb0e | 1205 | if (cmd == SEM_STAT) { |
16df3674 DB |
1206 | sma = sem_obtain_object(ns, semid); |
1207 | if (IS_ERR(sma)) { | |
1208 | err = PTR_ERR(sma); | |
1209 | goto out_unlock; | |
1210 | } | |
4b9fcb0e PP |
1211 | id = sma->sem_perm.id; |
1212 | } else { | |
16df3674 DB |
1213 | sma = sem_obtain_object_check(ns, semid); |
1214 | if (IS_ERR(sma)) { | |
1215 | err = PTR_ERR(sma); | |
1216 | goto out_unlock; | |
1217 | } | |
4b9fcb0e | 1218 | } |
1da177e4 LT |
1219 | |
1220 | err = -EACCES; | |
b0e77598 | 1221 | if (ipcperms(ns, &sma->sem_perm, S_IRUGO)) |
1da177e4 LT |
1222 | goto out_unlock; |
1223 | ||
1224 | err = security_sem_semctl(sma, cmd); | |
1225 | if (err) | |
1226 | goto out_unlock; | |
1227 | ||
1da177e4 | 1228 | kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); |
bf6830ad MS |
1229 | tbuf.sem_otime = get_semotime(sma); |
1230 | tbuf.sem_ctime = sma->sem_ctime; | |
1231 | tbuf.sem_nsems = sma->sem_nsems; | |
16df3674 | 1232 | rcu_read_unlock(); |
e1fd1f49 | 1233 | if (copy_semid_to_user(p, &tbuf, version)) |
1da177e4 LT |
1234 | return -EFAULT; |
1235 | return id; | |
1236 | } | |
1237 | default: | |
1238 | return -EINVAL; | |
1239 | } | |
1da177e4 | 1240 | out_unlock: |
16df3674 | 1241 | rcu_read_unlock(); |
1da177e4 LT |
1242 | return err; |
1243 | } | |
1244 | ||
e1fd1f49 AV |
1245 | static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, |
1246 | unsigned long arg) | |
1247 | { | |
1248 | struct sem_undo *un; | |
1249 | struct sem_array *sma; | |
1250 | struct sem* curr; | |
1251 | int err; | |
e1fd1f49 AV |
1252 | struct list_head tasks; |
1253 | int val; | |
1254 | #if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN) | |
1255 | /* big-endian 64bit */ | |
1256 | val = arg >> 32; | |
1257 | #else | |
1258 | /* 32bit or little-endian 64bit */ | |
1259 | val = arg; | |
1260 | #endif | |
1261 | ||
6062a8dc RR |
1262 | if (val > SEMVMX || val < 0) |
1263 | return -ERANGE; | |
e1fd1f49 AV |
1264 | |
1265 | INIT_LIST_HEAD(&tasks); | |
e1fd1f49 | 1266 | |
6062a8dc RR |
1267 | rcu_read_lock(); |
1268 | sma = sem_obtain_object_check(ns, semid); | |
1269 | if (IS_ERR(sma)) { | |
1270 | rcu_read_unlock(); | |
1271 | return PTR_ERR(sma); | |
1272 | } | |
1273 | ||
1274 | if (semnum < 0 || semnum >= sma->sem_nsems) { | |
1275 | rcu_read_unlock(); | |
1276 | return -EINVAL; | |
1277 | } | |
1278 | ||
1279 | ||
1280 | if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) { | |
1281 | rcu_read_unlock(); | |
1282 | return -EACCES; | |
1283 | } | |
e1fd1f49 AV |
1284 | |
1285 | err = security_sem_semctl(sma, SETVAL); | |
6062a8dc RR |
1286 | if (err) { |
1287 | rcu_read_unlock(); | |
1288 | return -EACCES; | |
1289 | } | |
e1fd1f49 | 1290 | |
6062a8dc | 1291 | sem_lock(sma, NULL, -1); |
e1fd1f49 | 1292 | |
873be93b MS |
1293 | if (sma->sem_perm.deleted) { |
1294 | sem_unlock(sma, -1); | |
1295 | rcu_read_unlock(); | |
1296 | return -EIDRM; | |
1297 | } | |
1298 | ||
e1fd1f49 AV |
1299 | curr = &sma->sem_base[semnum]; |
1300 | ||
115d40db | 1301 | ipc_assert_locked_object(&sma->sem_perm); |
e1fd1f49 AV |
1302 | list_for_each_entry(un, &sma->list_id, list_id) |
1303 | un->semadj[semnum] = 0; | |
1304 | ||
1305 | curr->semval = val; | |
1306 | curr->sempid = task_tgid_vnr(current); | |
1307 | sma->sem_ctime = get_seconds(); | |
1308 | /* maybe some queued-up processes were waiting for this */ | |
1309 | do_smart_update(sma, NULL, 0, 0, &tasks); | |
6062a8dc | 1310 | sem_unlock(sma, -1); |
6d49dab8 | 1311 | rcu_read_unlock(); |
e1fd1f49 | 1312 | wake_up_sem_queue_do(&tasks); |
6062a8dc | 1313 | return 0; |
e1fd1f49 AV |
1314 | } |
1315 | ||
e3893534 | 1316 | static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, |
e1fd1f49 | 1317 | int cmd, void __user *p) |
1da177e4 LT |
1318 | { |
1319 | struct sem_array *sma; | |
1320 | struct sem* curr; | |
16df3674 | 1321 | int err, nsems; |
1da177e4 LT |
1322 | ushort fast_sem_io[SEMMSL_FAST]; |
1323 | ushort* sem_io = fast_sem_io; | |
0a2b9d4c | 1324 | struct list_head tasks; |
1da177e4 | 1325 | |
16df3674 DB |
1326 | INIT_LIST_HEAD(&tasks); |
1327 | ||
1328 | rcu_read_lock(); | |
1329 | sma = sem_obtain_object_check(ns, semid); | |
1330 | if (IS_ERR(sma)) { | |
1331 | rcu_read_unlock(); | |
023a5355 | 1332 | return PTR_ERR(sma); |
16df3674 | 1333 | } |
1da177e4 LT |
1334 | |
1335 | nsems = sma->sem_nsems; | |
1336 | ||
1da177e4 | 1337 | err = -EACCES; |
c728b9c8 LT |
1338 | if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO)) |
1339 | goto out_rcu_wakeup; | |
1da177e4 LT |
1340 | |
1341 | err = security_sem_semctl(sma, cmd); | |
c728b9c8 LT |
1342 | if (err) |
1343 | goto out_rcu_wakeup; | |
1da177e4 LT |
1344 | |
1345 | err = -EACCES; | |
1346 | switch (cmd) { | |
1347 | case GETALL: | |
1348 | { | |
e1fd1f49 | 1349 | ushort __user *array = p; |
1da177e4 LT |
1350 | int i; |
1351 | ||
ce857229 | 1352 | sem_lock(sma, NULL, -1); |
873be93b MS |
1353 | if (sma->sem_perm.deleted) { |
1354 | err = -EIDRM; | |
1355 | goto out_unlock; | |
1356 | } | |
1da177e4 | 1357 | if(nsems > SEMMSL_FAST) { |
ce857229 | 1358 | if (!ipc_rcu_getref(sma)) { |
ce857229 | 1359 | err = -EIDRM; |
873be93b | 1360 | goto out_unlock; |
ce857229 AV |
1361 | } |
1362 | sem_unlock(sma, -1); | |
6d49dab8 | 1363 | rcu_read_unlock(); |
1da177e4 LT |
1364 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
1365 | if(sem_io == NULL) { | |
e84ca333 | 1366 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1367 | return -ENOMEM; |
1368 | } | |
1369 | ||
4091fd94 | 1370 | rcu_read_lock(); |
6ff37972 | 1371 | sem_lock_and_putref(sma); |
1da177e4 | 1372 | if (sma->sem_perm.deleted) { |
1da177e4 | 1373 | err = -EIDRM; |
873be93b | 1374 | goto out_unlock; |
1da177e4 | 1375 | } |
ce857229 | 1376 | } |
1da177e4 LT |
1377 | for (i = 0; i < sma->sem_nsems; i++) |
1378 | sem_io[i] = sma->sem_base[i].semval; | |
6062a8dc | 1379 | sem_unlock(sma, -1); |
6d49dab8 | 1380 | rcu_read_unlock(); |
1da177e4 LT |
1381 | err = 0; |
1382 | if(copy_to_user(array, sem_io, nsems*sizeof(ushort))) | |
1383 | err = -EFAULT; | |
1384 | goto out_free; | |
1385 | } | |
1386 | case SETALL: | |
1387 | { | |
1388 | int i; | |
1389 | struct sem_undo *un; | |
1390 | ||
6062a8dc | 1391 | if (!ipc_rcu_getref(sma)) { |
873be93b MS |
1392 | err = -EIDRM; |
1393 | goto out_rcu_wakeup; | |
6062a8dc | 1394 | } |
16df3674 | 1395 | rcu_read_unlock(); |
1da177e4 LT |
1396 | |
1397 | if(nsems > SEMMSL_FAST) { | |
1398 | sem_io = ipc_alloc(sizeof(ushort)*nsems); | |
1399 | if(sem_io == NULL) { | |
e84ca333 | 1400 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1401 | return -ENOMEM; |
1402 | } | |
1403 | } | |
1404 | ||
e1fd1f49 | 1405 | if (copy_from_user (sem_io, p, nsems*sizeof(ushort))) { |
e84ca333 | 1406 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1407 | err = -EFAULT; |
1408 | goto out_free; | |
1409 | } | |
1410 | ||
1411 | for (i = 0; i < nsems; i++) { | |
1412 | if (sem_io[i] > SEMVMX) { | |
e84ca333 | 1413 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1414 | err = -ERANGE; |
1415 | goto out_free; | |
1416 | } | |
1417 | } | |
4091fd94 | 1418 | rcu_read_lock(); |
6ff37972 | 1419 | sem_lock_and_putref(sma); |
1da177e4 | 1420 | if (sma->sem_perm.deleted) { |
1da177e4 | 1421 | err = -EIDRM; |
873be93b | 1422 | goto out_unlock; |
1da177e4 LT |
1423 | } |
1424 | ||
1425 | for (i = 0; i < nsems; i++) | |
1426 | sma->sem_base[i].semval = sem_io[i]; | |
4daa28f6 | 1427 | |
115d40db | 1428 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1429 | list_for_each_entry(un, &sma->list_id, list_id) { |
1da177e4 LT |
1430 | for (i = 0; i < nsems; i++) |
1431 | un->semadj[i] = 0; | |
4daa28f6 | 1432 | } |
1da177e4 LT |
1433 | sma->sem_ctime = get_seconds(); |
1434 | /* maybe some queued-up processes were waiting for this */ | |
0a2b9d4c | 1435 | do_smart_update(sma, NULL, 0, 0, &tasks); |
1da177e4 LT |
1436 | err = 0; |
1437 | goto out_unlock; | |
1438 | } | |
e1fd1f49 | 1439 | /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */ |
1da177e4 LT |
1440 | } |
1441 | err = -EINVAL; | |
c728b9c8 LT |
1442 | if (semnum < 0 || semnum >= nsems) |
1443 | goto out_rcu_wakeup; | |
1da177e4 | 1444 | |
6062a8dc | 1445 | sem_lock(sma, NULL, -1); |
873be93b MS |
1446 | if (sma->sem_perm.deleted) { |
1447 | err = -EIDRM; | |
1448 | goto out_unlock; | |
1449 | } | |
1da177e4 LT |
1450 | curr = &sma->sem_base[semnum]; |
1451 | ||
1452 | switch (cmd) { | |
1453 | case GETVAL: | |
1454 | err = curr->semval; | |
1455 | goto out_unlock; | |
1456 | case GETPID: | |
1457 | err = curr->sempid; | |
1458 | goto out_unlock; | |
1459 | case GETNCNT: | |
1460 | err = count_semncnt(sma,semnum); | |
1461 | goto out_unlock; | |
1462 | case GETZCNT: | |
1463 | err = count_semzcnt(sma,semnum); | |
1464 | goto out_unlock; | |
1da177e4 | 1465 | } |
16df3674 | 1466 | |
1da177e4 | 1467 | out_unlock: |
6062a8dc | 1468 | sem_unlock(sma, -1); |
c728b9c8 | 1469 | out_rcu_wakeup: |
6d49dab8 | 1470 | rcu_read_unlock(); |
0a2b9d4c | 1471 | wake_up_sem_queue_do(&tasks); |
1da177e4 LT |
1472 | out_free: |
1473 | if(sem_io != fast_sem_io) | |
1474 | ipc_free(sem_io, sizeof(ushort)*nsems); | |
1475 | return err; | |
1476 | } | |
1477 | ||
016d7132 PP |
1478 | static inline unsigned long |
1479 | copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) | |
1da177e4 LT |
1480 | { |
1481 | switch(version) { | |
1482 | case IPC_64: | |
016d7132 | 1483 | if (copy_from_user(out, buf, sizeof(*out))) |
1da177e4 | 1484 | return -EFAULT; |
1da177e4 | 1485 | return 0; |
1da177e4 LT |
1486 | case IPC_OLD: |
1487 | { | |
1488 | struct semid_ds tbuf_old; | |
1489 | ||
1490 | if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) | |
1491 | return -EFAULT; | |
1492 | ||
016d7132 PP |
1493 | out->sem_perm.uid = tbuf_old.sem_perm.uid; |
1494 | out->sem_perm.gid = tbuf_old.sem_perm.gid; | |
1495 | out->sem_perm.mode = tbuf_old.sem_perm.mode; | |
1da177e4 LT |
1496 | |
1497 | return 0; | |
1498 | } | |
1499 | default: | |
1500 | return -EINVAL; | |
1501 | } | |
1502 | } | |
1503 | ||
522bb2a2 | 1504 | /* |
33b74669 | 1505 | * This function handles some semctl commands which require the rwsem |
522bb2a2 | 1506 | * to be held in write mode. |
33b74669 | 1507 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
522bb2a2 | 1508 | */ |
21a4826a | 1509 | static int semctl_down(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1510 | int cmd, int version, void __user *p) |
1da177e4 LT |
1511 | { |
1512 | struct sem_array *sma; | |
1513 | int err; | |
016d7132 | 1514 | struct semid64_ds semid64; |
1da177e4 LT |
1515 | struct kern_ipc_perm *ipcp; |
1516 | ||
1517 | if(cmd == IPC_SET) { | |
e1fd1f49 | 1518 | if (copy_semid_from_user(&semid64, p, version)) |
1da177e4 | 1519 | return -EFAULT; |
1da177e4 | 1520 | } |
073115d6 | 1521 | |
33b74669 | 1522 | down_write(&sem_ids(ns).rwsem); |
ac9bc6e3 DB |
1523 | rcu_read_lock(); |
1524 | ||
16df3674 DB |
1525 | ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd, |
1526 | &semid64.sem_perm, 0); | |
ac9bc6e3 DB |
1527 | if (IS_ERR(ipcp)) { |
1528 | err = PTR_ERR(ipcp); | |
ac9bc6e3 DB |
1529 | goto out_unlock1; |
1530 | } | |
073115d6 | 1531 | |
a5f75e7f | 1532 | sma = container_of(ipcp, struct sem_array, sem_perm); |
1da177e4 LT |
1533 | |
1534 | err = security_sem_semctl(sma, cmd); | |
ac9bc6e3 DB |
1535 | if (err) |
1536 | goto out_unlock1; | |
1da177e4 | 1537 | |
ac9bc6e3 | 1538 | switch (cmd) { |
1da177e4 | 1539 | case IPC_RMID: |
6062a8dc | 1540 | sem_lock(sma, NULL, -1); |
ac9bc6e3 | 1541 | /* freeary unlocks the ipc object and rcu */ |
01b8b07a | 1542 | freeary(ns, ipcp); |
522bb2a2 | 1543 | goto out_up; |
1da177e4 | 1544 | case IPC_SET: |
6062a8dc | 1545 | sem_lock(sma, NULL, -1); |
1efdb69b EB |
1546 | err = ipc_update_perm(&semid64.sem_perm, ipcp); |
1547 | if (err) | |
ac9bc6e3 | 1548 | goto out_unlock0; |
1da177e4 | 1549 | sma->sem_ctime = get_seconds(); |
1da177e4 LT |
1550 | break; |
1551 | default: | |
1da177e4 | 1552 | err = -EINVAL; |
ac9bc6e3 | 1553 | goto out_unlock1; |
1da177e4 | 1554 | } |
1da177e4 | 1555 | |
ac9bc6e3 | 1556 | out_unlock0: |
6062a8dc | 1557 | sem_unlock(sma, -1); |
ac9bc6e3 | 1558 | out_unlock1: |
6d49dab8 | 1559 | rcu_read_unlock(); |
522bb2a2 | 1560 | out_up: |
33b74669 | 1561 | up_write(&sem_ids(ns).rwsem); |
1da177e4 LT |
1562 | return err; |
1563 | } | |
1564 | ||
e1fd1f49 | 1565 | SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) |
1da177e4 | 1566 | { |
1da177e4 | 1567 | int version; |
e3893534 | 1568 | struct ipc_namespace *ns; |
e1fd1f49 | 1569 | void __user *p = (void __user *)arg; |
1da177e4 LT |
1570 | |
1571 | if (semid < 0) | |
1572 | return -EINVAL; | |
1573 | ||
1574 | version = ipc_parse_version(&cmd); | |
e3893534 | 1575 | ns = current->nsproxy->ipc_ns; |
1da177e4 LT |
1576 | |
1577 | switch(cmd) { | |
1578 | case IPC_INFO: | |
1579 | case SEM_INFO: | |
4b9fcb0e | 1580 | case IPC_STAT: |
1da177e4 | 1581 | case SEM_STAT: |
e1fd1f49 | 1582 | return semctl_nolock(ns, semid, cmd, version, p); |
1da177e4 LT |
1583 | case GETALL: |
1584 | case GETVAL: | |
1585 | case GETPID: | |
1586 | case GETNCNT: | |
1587 | case GETZCNT: | |
1da177e4 | 1588 | case SETALL: |
e1fd1f49 AV |
1589 | return semctl_main(ns, semid, semnum, cmd, p); |
1590 | case SETVAL: | |
1591 | return semctl_setval(ns, semid, semnum, arg); | |
1da177e4 LT |
1592 | case IPC_RMID: |
1593 | case IPC_SET: | |
e1fd1f49 | 1594 | return semctl_down(ns, semid, cmd, version, p); |
1da177e4 LT |
1595 | default: |
1596 | return -EINVAL; | |
1597 | } | |
1598 | } | |
1599 | ||
1da177e4 LT |
1600 | /* If the task doesn't already have a undo_list, then allocate one |
1601 | * here. We guarantee there is only one thread using this undo list, | |
1602 | * and current is THE ONE | |
1603 | * | |
1604 | * If this allocation and assignment succeeds, but later | |
1605 | * portions of this code fail, there is no need to free the sem_undo_list. | |
1606 | * Just let it stay associated with the task, and it'll be freed later | |
1607 | * at exit time. | |
1608 | * | |
1609 | * This can block, so callers must hold no locks. | |
1610 | */ | |
1611 | static inline int get_undo_list(struct sem_undo_list **undo_listp) | |
1612 | { | |
1613 | struct sem_undo_list *undo_list; | |
1da177e4 LT |
1614 | |
1615 | undo_list = current->sysvsem.undo_list; | |
1616 | if (!undo_list) { | |
2453a306 | 1617 | undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL); |
1da177e4 LT |
1618 | if (undo_list == NULL) |
1619 | return -ENOMEM; | |
00a5dfdb | 1620 | spin_lock_init(&undo_list->lock); |
1da177e4 | 1621 | atomic_set(&undo_list->refcnt, 1); |
4daa28f6 MS |
1622 | INIT_LIST_HEAD(&undo_list->list_proc); |
1623 | ||
1da177e4 LT |
1624 | current->sysvsem.undo_list = undo_list; |
1625 | } | |
1626 | *undo_listp = undo_list; | |
1627 | return 0; | |
1628 | } | |
1629 | ||
bf17bb71 | 1630 | static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid) |
1da177e4 | 1631 | { |
bf17bb71 | 1632 | struct sem_undo *un; |
4daa28f6 | 1633 | |
bf17bb71 NP |
1634 | list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) { |
1635 | if (un->semid == semid) | |
1636 | return un; | |
1da177e4 | 1637 | } |
4daa28f6 | 1638 | return NULL; |
1da177e4 LT |
1639 | } |
1640 | ||
bf17bb71 NP |
1641 | static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) |
1642 | { | |
1643 | struct sem_undo *un; | |
1644 | ||
1645 | assert_spin_locked(&ulp->lock); | |
1646 | ||
1647 | un = __lookup_undo(ulp, semid); | |
1648 | if (un) { | |
1649 | list_del_rcu(&un->list_proc); | |
1650 | list_add_rcu(&un->list_proc, &ulp->list_proc); | |
1651 | } | |
1652 | return un; | |
1653 | } | |
1654 | ||
4daa28f6 MS |
1655 | /** |
1656 | * find_alloc_undo - Lookup (and if not present create) undo array | |
1657 | * @ns: namespace | |
1658 | * @semid: semaphore array id | |
1659 | * | |
1660 | * The function looks up (and if not present creates) the undo structure. | |
1661 | * The size of the undo structure depends on the size of the semaphore | |
1662 | * array, thus the alloc path is not that straightforward. | |
380af1b3 MS |
1663 | * Lifetime-rules: sem_undo is rcu-protected, on success, the function |
1664 | * performs a rcu_read_lock(). | |
4daa28f6 MS |
1665 | */ |
1666 | static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) | |
1da177e4 LT |
1667 | { |
1668 | struct sem_array *sma; | |
1669 | struct sem_undo_list *ulp; | |
1670 | struct sem_undo *un, *new; | |
6062a8dc | 1671 | int nsems, error; |
1da177e4 LT |
1672 | |
1673 | error = get_undo_list(&ulp); | |
1674 | if (error) | |
1675 | return ERR_PTR(error); | |
1676 | ||
380af1b3 | 1677 | rcu_read_lock(); |
c530c6ac | 1678 | spin_lock(&ulp->lock); |
1da177e4 | 1679 | un = lookup_undo(ulp, semid); |
c530c6ac | 1680 | spin_unlock(&ulp->lock); |
1da177e4 LT |
1681 | if (likely(un!=NULL)) |
1682 | goto out; | |
1683 | ||
1684 | /* no undo structure around - allocate one. */ | |
4daa28f6 | 1685 | /* step 1: figure out the size of the semaphore array */ |
16df3674 DB |
1686 | sma = sem_obtain_object_check(ns, semid); |
1687 | if (IS_ERR(sma)) { | |
1688 | rcu_read_unlock(); | |
4de85cd6 | 1689 | return ERR_CAST(sma); |
16df3674 | 1690 | } |
023a5355 | 1691 | |
1da177e4 | 1692 | nsems = sma->sem_nsems; |
6062a8dc RR |
1693 | if (!ipc_rcu_getref(sma)) { |
1694 | rcu_read_unlock(); | |
1695 | un = ERR_PTR(-EIDRM); | |
1696 | goto out; | |
1697 | } | |
16df3674 | 1698 | rcu_read_unlock(); |
1da177e4 | 1699 | |
4daa28f6 | 1700 | /* step 2: allocate new undo structure */ |
4668edc3 | 1701 | new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); |
1da177e4 | 1702 | if (!new) { |
e84ca333 | 1703 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1704 | return ERR_PTR(-ENOMEM); |
1705 | } | |
1da177e4 | 1706 | |
380af1b3 | 1707 | /* step 3: Acquire the lock on semaphore array */ |
4091fd94 | 1708 | rcu_read_lock(); |
6ff37972 | 1709 | sem_lock_and_putref(sma); |
1da177e4 | 1710 | if (sma->sem_perm.deleted) { |
6062a8dc | 1711 | sem_unlock(sma, -1); |
6d49dab8 | 1712 | rcu_read_unlock(); |
1da177e4 LT |
1713 | kfree(new); |
1714 | un = ERR_PTR(-EIDRM); | |
1715 | goto out; | |
1716 | } | |
380af1b3 MS |
1717 | spin_lock(&ulp->lock); |
1718 | ||
1719 | /* | |
1720 | * step 4: check for races: did someone else allocate the undo struct? | |
1721 | */ | |
1722 | un = lookup_undo(ulp, semid); | |
1723 | if (un) { | |
1724 | kfree(new); | |
1725 | goto success; | |
1726 | } | |
4daa28f6 MS |
1727 | /* step 5: initialize & link new undo structure */ |
1728 | new->semadj = (short *) &new[1]; | |
380af1b3 | 1729 | new->ulp = ulp; |
4daa28f6 MS |
1730 | new->semid = semid; |
1731 | assert_spin_locked(&ulp->lock); | |
380af1b3 | 1732 | list_add_rcu(&new->list_proc, &ulp->list_proc); |
115d40db | 1733 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1734 | list_add(&new->list_id, &sma->list_id); |
380af1b3 | 1735 | un = new; |
4daa28f6 | 1736 | |
380af1b3 | 1737 | success: |
c530c6ac | 1738 | spin_unlock(&ulp->lock); |
6062a8dc | 1739 | sem_unlock(sma, -1); |
1da177e4 LT |
1740 | out: |
1741 | return un; | |
1742 | } | |
1743 | ||
c61284e9 MS |
1744 | |
1745 | /** | |
1746 | * get_queue_result - Retrieve the result code from sem_queue | |
1747 | * @q: Pointer to queue structure | |
1748 | * | |
1749 | * Retrieve the return code from the pending queue. If IN_WAKEUP is found in | |
1750 | * q->status, then we must loop until the value is replaced with the final | |
1751 | * value: This may happen if a task is woken up by an unrelated event (e.g. | |
1752 | * signal) and in parallel the task is woken up by another task because it got | |
1753 | * the requested semaphores. | |
1754 | * | |
1755 | * The function can be called with or without holding the semaphore spinlock. | |
1756 | */ | |
1757 | static int get_queue_result(struct sem_queue *q) | |
1758 | { | |
1759 | int error; | |
1760 | ||
1761 | error = q->status; | |
1762 | while (unlikely(error == IN_WAKEUP)) { | |
1763 | cpu_relax(); | |
1764 | error = q->status; | |
1765 | } | |
1766 | ||
1767 | return error; | |
1768 | } | |
1769 | ||
d5460c99 HC |
1770 | SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, |
1771 | unsigned, nsops, const struct timespec __user *, timeout) | |
1da177e4 LT |
1772 | { |
1773 | int error = -EINVAL; | |
1774 | struct sem_array *sma; | |
1775 | struct sembuf fast_sops[SEMOPM_FAST]; | |
1776 | struct sembuf* sops = fast_sops, *sop; | |
1777 | struct sem_undo *un; | |
6062a8dc | 1778 | int undos = 0, alter = 0, max, locknum; |
1da177e4 LT |
1779 | struct sem_queue queue; |
1780 | unsigned long jiffies_left = 0; | |
e3893534 | 1781 | struct ipc_namespace *ns; |
0a2b9d4c | 1782 | struct list_head tasks; |
e3893534 KK |
1783 | |
1784 | ns = current->nsproxy->ipc_ns; | |
1da177e4 LT |
1785 | |
1786 | if (nsops < 1 || semid < 0) | |
1787 | return -EINVAL; | |
e3893534 | 1788 | if (nsops > ns->sc_semopm) |
1da177e4 LT |
1789 | return -E2BIG; |
1790 | if(nsops > SEMOPM_FAST) { | |
1791 | sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL); | |
1792 | if(sops==NULL) | |
1793 | return -ENOMEM; | |
1794 | } | |
1795 | if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) { | |
1796 | error=-EFAULT; | |
1797 | goto out_free; | |
1798 | } | |
1799 | if (timeout) { | |
1800 | struct timespec _timeout; | |
1801 | if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { | |
1802 | error = -EFAULT; | |
1803 | goto out_free; | |
1804 | } | |
1805 | if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || | |
1806 | _timeout.tv_nsec >= 1000000000L) { | |
1807 | error = -EINVAL; | |
1808 | goto out_free; | |
1809 | } | |
1810 | jiffies_left = timespec_to_jiffies(&_timeout); | |
1811 | } | |
1812 | max = 0; | |
1813 | for (sop = sops; sop < sops + nsops; sop++) { | |
1814 | if (sop->sem_num >= max) | |
1815 | max = sop->sem_num; | |
1816 | if (sop->sem_flg & SEM_UNDO) | |
b78755ab MS |
1817 | undos = 1; |
1818 | if (sop->sem_op != 0) | |
1da177e4 LT |
1819 | alter = 1; |
1820 | } | |
1da177e4 | 1821 | |
6062a8dc RR |
1822 | INIT_LIST_HEAD(&tasks); |
1823 | ||
1da177e4 | 1824 | if (undos) { |
6062a8dc | 1825 | /* On success, find_alloc_undo takes the rcu_read_lock */ |
4daa28f6 | 1826 | un = find_alloc_undo(ns, semid); |
1da177e4 LT |
1827 | if (IS_ERR(un)) { |
1828 | error = PTR_ERR(un); | |
1829 | goto out_free; | |
1830 | } | |
6062a8dc | 1831 | } else { |
1da177e4 | 1832 | un = NULL; |
6062a8dc RR |
1833 | rcu_read_lock(); |
1834 | } | |
1da177e4 | 1835 | |
16df3674 | 1836 | sma = sem_obtain_object_check(ns, semid); |
023a5355 | 1837 | if (IS_ERR(sma)) { |
6062a8dc | 1838 | rcu_read_unlock(); |
023a5355 | 1839 | error = PTR_ERR(sma); |
1da177e4 | 1840 | goto out_free; |
023a5355 ND |
1841 | } |
1842 | ||
16df3674 | 1843 | error = -EFBIG; |
c728b9c8 LT |
1844 | if (max >= sma->sem_nsems) |
1845 | goto out_rcu_wakeup; | |
16df3674 DB |
1846 | |
1847 | error = -EACCES; | |
c728b9c8 LT |
1848 | if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) |
1849 | goto out_rcu_wakeup; | |
16df3674 DB |
1850 | |
1851 | error = security_sem_semop(sma, sops, nsops, alter); | |
c728b9c8 LT |
1852 | if (error) |
1853 | goto out_rcu_wakeup; | |
16df3674 | 1854 | |
873be93b MS |
1855 | error = -EIDRM; |
1856 | locknum = sem_lock(sma, sops, nsops); | |
1857 | if (sma->sem_perm.deleted) | |
1858 | goto out_unlock_free; | |
1da177e4 | 1859 | /* |
4daa28f6 | 1860 | * semid identifiers are not unique - find_alloc_undo may have |
1da177e4 | 1861 | * allocated an undo structure, it was invalidated by an RMID |
4daa28f6 | 1862 | * and now a new array with received the same id. Check and fail. |
25985edc | 1863 | * This case can be detected checking un->semid. The existence of |
380af1b3 | 1864 | * "un" itself is guaranteed by rcu. |
1da177e4 | 1865 | */ |
6062a8dc RR |
1866 | if (un && un->semid == -1) |
1867 | goto out_unlock_free; | |
4daa28f6 | 1868 | |
b56e88e2 MS |
1869 | error = perform_atomic_semop(sma, sops, nsops, un, |
1870 | task_tgid_vnr(current)); | |
e556ea01 MS |
1871 | if (error == 0) { |
1872 | /* If the operation was successful, then do | |
1873 | * the required updates. | |
1874 | */ | |
1875 | if (alter) | |
0a2b9d4c | 1876 | do_smart_update(sma, sops, nsops, 1, &tasks); |
e556ea01 MS |
1877 | else |
1878 | set_semotime(sma, sops); | |
1da177e4 | 1879 | } |
e556ea01 MS |
1880 | if (error <= 0) |
1881 | goto out_unlock_free; | |
1da177e4 LT |
1882 | |
1883 | /* We need to sleep on this operation, so we put the current | |
1884 | * task into the pending queue and go to sleep. | |
1885 | */ | |
1886 | ||
1da177e4 LT |
1887 | queue.sops = sops; |
1888 | queue.nsops = nsops; | |
1889 | queue.undo = un; | |
b488893a | 1890 | queue.pid = task_tgid_vnr(current); |
1da177e4 | 1891 | queue.alter = alter; |
1da177e4 | 1892 | |
b97e820f MS |
1893 | if (nsops == 1) { |
1894 | struct sem *curr; | |
1895 | curr = &sma->sem_base[sops->sem_num]; | |
1896 | ||
e5639c52 MS |
1897 | if (alter) { |
1898 | if (sma->complex_count) { | |
1899 | list_add_tail(&queue.list, | |
1900 | &sma->pending_alter); | |
1901 | } else { | |
1902 | ||
1903 | list_add_tail(&queue.list, | |
1904 | &curr->pending_alter); | |
1905 | } | |
1906 | } else { | |
ab63bc97 | 1907 | list_add_tail(&queue.list, &curr->pending_const); |
e5639c52 | 1908 | } |
b97e820f | 1909 | } else { |
e5639c52 MS |
1910 | if (!sma->complex_count) |
1911 | merge_queues(sma); | |
1912 | ||
9f1bc2c9 | 1913 | if (alter) |
ab63bc97 | 1914 | list_add_tail(&queue.list, &sma->pending_alter); |
9f1bc2c9 | 1915 | else |
ab63bc97 MS |
1916 | list_add_tail(&queue.list, &sma->pending_const); |
1917 | ||
b97e820f MS |
1918 | sma->complex_count++; |
1919 | } | |
1920 | ||
1da177e4 LT |
1921 | queue.status = -EINTR; |
1922 | queue.sleeper = current; | |
0b0577f6 MS |
1923 | |
1924 | sleep_again: | |
1da177e4 | 1925 | current->state = TASK_INTERRUPTIBLE; |
6062a8dc | 1926 | sem_unlock(sma, locknum); |
6d49dab8 | 1927 | rcu_read_unlock(); |
1da177e4 LT |
1928 | |
1929 | if (timeout) | |
1930 | jiffies_left = schedule_timeout(jiffies_left); | |
1931 | else | |
1932 | schedule(); | |
1933 | ||
c61284e9 | 1934 | error = get_queue_result(&queue); |
1da177e4 LT |
1935 | |
1936 | if (error != -EINTR) { | |
1937 | /* fast path: update_queue already obtained all requested | |
c61284e9 MS |
1938 | * resources. |
1939 | * Perform a smp_mb(): User space could assume that semop() | |
1940 | * is a memory barrier: Without the mb(), the cpu could | |
1941 | * speculatively read in user space stale data that was | |
1942 | * overwritten by the previous owner of the semaphore. | |
1943 | */ | |
1944 | smp_mb(); | |
1945 | ||
1da177e4 LT |
1946 | goto out_free; |
1947 | } | |
1948 | ||
321310ce | 1949 | rcu_read_lock(); |
6062a8dc | 1950 | sma = sem_obtain_lock(ns, semid, sops, nsops, &locknum); |
d694ad62 MS |
1951 | |
1952 | /* | |
1953 | * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing. | |
1954 | */ | |
1955 | error = get_queue_result(&queue); | |
1956 | ||
1957 | /* | |
1958 | * Array removed? If yes, leave without sem_unlock(). | |
1959 | */ | |
023a5355 | 1960 | if (IS_ERR(sma)) { |
321310ce | 1961 | rcu_read_unlock(); |
1da177e4 LT |
1962 | goto out_free; |
1963 | } | |
1964 | ||
c61284e9 | 1965 | |
1da177e4 | 1966 | /* |
d694ad62 MS |
1967 | * If queue.status != -EINTR we are woken up by another process. |
1968 | * Leave without unlink_queue(), but with sem_unlock(). | |
1da177e4 | 1969 | */ |
c61284e9 | 1970 | |
1da177e4 LT |
1971 | if (error != -EINTR) { |
1972 | goto out_unlock_free; | |
1973 | } | |
1974 | ||
1975 | /* | |
1976 | * If an interrupt occurred we have to clean up the queue | |
1977 | */ | |
1978 | if (timeout && jiffies_left == 0) | |
1979 | error = -EAGAIN; | |
0b0577f6 MS |
1980 | |
1981 | /* | |
1982 | * If the wakeup was spurious, just retry | |
1983 | */ | |
1984 | if (error == -EINTR && !signal_pending(current)) | |
1985 | goto sleep_again; | |
1986 | ||
b97e820f | 1987 | unlink_queue(sma, &queue); |
1da177e4 LT |
1988 | |
1989 | out_unlock_free: | |
6062a8dc | 1990 | sem_unlock(sma, locknum); |
c728b9c8 | 1991 | out_rcu_wakeup: |
6d49dab8 | 1992 | rcu_read_unlock(); |
0a2b9d4c | 1993 | wake_up_sem_queue_do(&tasks); |
1da177e4 LT |
1994 | out_free: |
1995 | if(sops != fast_sops) | |
1996 | kfree(sops); | |
1997 | return error; | |
1998 | } | |
1999 | ||
d5460c99 HC |
2000 | SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops, |
2001 | unsigned, nsops) | |
1da177e4 LT |
2002 | { |
2003 | return sys_semtimedop(semid, tsops, nsops, NULL); | |
2004 | } | |
2005 | ||
2006 | /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between | |
2007 | * parent and child tasks. | |
1da177e4 LT |
2008 | */ |
2009 | ||
2010 | int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) | |
2011 | { | |
2012 | struct sem_undo_list *undo_list; | |
2013 | int error; | |
2014 | ||
2015 | if (clone_flags & CLONE_SYSVSEM) { | |
2016 | error = get_undo_list(&undo_list); | |
2017 | if (error) | |
2018 | return error; | |
1da177e4 LT |
2019 | atomic_inc(&undo_list->refcnt); |
2020 | tsk->sysvsem.undo_list = undo_list; | |
2021 | } else | |
2022 | tsk->sysvsem.undo_list = NULL; | |
2023 | ||
2024 | return 0; | |
2025 | } | |
2026 | ||
2027 | /* | |
2028 | * add semadj values to semaphores, free undo structures. | |
2029 | * undo structures are not freed when semaphore arrays are destroyed | |
2030 | * so some of them may be out of date. | |
2031 | * IMPLEMENTATION NOTE: There is some confusion over whether the | |
2032 | * set of adjustments that needs to be done should be done in an atomic | |
2033 | * manner or not. That is, if we are attempting to decrement the semval | |
2034 | * should we queue up and wait until we can do so legally? | |
2035 | * The original implementation attempted to do this (queue and wait). | |
2036 | * The current implementation does not do so. The POSIX standard | |
2037 | * and SVID should be consulted to determine what behavior is mandated. | |
2038 | */ | |
2039 | void exit_sem(struct task_struct *tsk) | |
2040 | { | |
4daa28f6 | 2041 | struct sem_undo_list *ulp; |
1da177e4 | 2042 | |
4daa28f6 MS |
2043 | ulp = tsk->sysvsem.undo_list; |
2044 | if (!ulp) | |
1da177e4 | 2045 | return; |
9edff4ab | 2046 | tsk->sysvsem.undo_list = NULL; |
1da177e4 | 2047 | |
4daa28f6 | 2048 | if (!atomic_dec_and_test(&ulp->refcnt)) |
1da177e4 LT |
2049 | return; |
2050 | ||
380af1b3 | 2051 | for (;;) { |
1da177e4 | 2052 | struct sem_array *sma; |
380af1b3 | 2053 | struct sem_undo *un; |
0a2b9d4c | 2054 | struct list_head tasks; |
6062a8dc | 2055 | int semid, i; |
4daa28f6 | 2056 | |
380af1b3 | 2057 | rcu_read_lock(); |
05725f7e JP |
2058 | un = list_entry_rcu(ulp->list_proc.next, |
2059 | struct sem_undo, list_proc); | |
04d2af28 HK |
2060 | if (&un->list_proc == &ulp->list_proc) { |
2061 | /* | |
2062 | * We must wait for freeary() before freeing this ulp, | |
2063 | * in case we raced with last sem_undo. There is a small | |
2064 | * possibility where we exit while freeary() didn't | |
2065 | * finish unlocking sem_undo_list. | |
2066 | */ | |
2067 | spin_unlock_wait(&ulp->lock); | |
2068 | rcu_read_unlock(); | |
2069 | break; | |
2070 | } | |
2071 | spin_lock(&ulp->lock); | |
2072 | semid = un->semid; | |
2073 | spin_unlock(&ulp->lock); | |
4daa28f6 | 2074 | |
04d2af28 | 2075 | /* exit_sem raced with IPC_RMID, nothing to do */ |
6062a8dc RR |
2076 | if (semid == -1) { |
2077 | rcu_read_unlock(); | |
04d2af28 | 2078 | continue; |
6062a8dc | 2079 | } |
1da177e4 | 2080 | |
04d2af28 | 2081 | sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, semid); |
380af1b3 | 2082 | /* exit_sem raced with IPC_RMID, nothing to do */ |
6062a8dc RR |
2083 | if (IS_ERR(sma)) { |
2084 | rcu_read_unlock(); | |
380af1b3 | 2085 | continue; |
6062a8dc | 2086 | } |
1da177e4 | 2087 | |
6062a8dc | 2088 | sem_lock(sma, NULL, -1); |
873be93b MS |
2089 | /* exit_sem raced with IPC_RMID, nothing to do */ |
2090 | if (sma->sem_perm.deleted) { | |
2091 | sem_unlock(sma, -1); | |
2092 | rcu_read_unlock(); | |
2093 | continue; | |
2094 | } | |
bf17bb71 | 2095 | un = __lookup_undo(ulp, semid); |
380af1b3 MS |
2096 | if (un == NULL) { |
2097 | /* exit_sem raced with IPC_RMID+semget() that created | |
2098 | * exactly the same semid. Nothing to do. | |
2099 | */ | |
6062a8dc | 2100 | sem_unlock(sma, -1); |
6d49dab8 | 2101 | rcu_read_unlock(); |
380af1b3 MS |
2102 | continue; |
2103 | } | |
2104 | ||
2105 | /* remove un from the linked lists */ | |
115d40db | 2106 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 MS |
2107 | list_del(&un->list_id); |
2108 | ||
380af1b3 MS |
2109 | spin_lock(&ulp->lock); |
2110 | list_del_rcu(&un->list_proc); | |
2111 | spin_unlock(&ulp->lock); | |
2112 | ||
4daa28f6 MS |
2113 | /* perform adjustments registered in un */ |
2114 | for (i = 0; i < sma->sem_nsems; i++) { | |
5f921ae9 | 2115 | struct sem * semaphore = &sma->sem_base[i]; |
4daa28f6 MS |
2116 | if (un->semadj[i]) { |
2117 | semaphore->semval += un->semadj[i]; | |
1da177e4 LT |
2118 | /* |
2119 | * Range checks of the new semaphore value, | |
2120 | * not defined by sus: | |
2121 | * - Some unices ignore the undo entirely | |
2122 | * (e.g. HP UX 11i 11.22, Tru64 V5.1) | |
2123 | * - some cap the value (e.g. FreeBSD caps | |
2124 | * at 0, but doesn't enforce SEMVMX) | |
2125 | * | |
2126 | * Linux caps the semaphore value, both at 0 | |
2127 | * and at SEMVMX. | |
2128 | * | |
2129 | * Manfred <manfred@colorfullife.com> | |
2130 | */ | |
5f921ae9 IM |
2131 | if (semaphore->semval < 0) |
2132 | semaphore->semval = 0; | |
2133 | if (semaphore->semval > SEMVMX) | |
2134 | semaphore->semval = SEMVMX; | |
b488893a | 2135 | semaphore->sempid = task_tgid_vnr(current); |
1da177e4 LT |
2136 | } |
2137 | } | |
1da177e4 | 2138 | /* maybe some queued-up processes were waiting for this */ |
0a2b9d4c MS |
2139 | INIT_LIST_HEAD(&tasks); |
2140 | do_smart_update(sma, NULL, 0, 1, &tasks); | |
6062a8dc | 2141 | sem_unlock(sma, -1); |
6d49dab8 | 2142 | rcu_read_unlock(); |
0a2b9d4c | 2143 | wake_up_sem_queue_do(&tasks); |
380af1b3 | 2144 | |
693a8b6e | 2145 | kfree_rcu(un, rcu); |
1da177e4 | 2146 | } |
4daa28f6 | 2147 | kfree(ulp); |
1da177e4 LT |
2148 | } |
2149 | ||
2150 | #ifdef CONFIG_PROC_FS | |
19b4946c | 2151 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it) |
1da177e4 | 2152 | { |
1efdb69b | 2153 | struct user_namespace *user_ns = seq_user_ns(s); |
19b4946c | 2154 | struct sem_array *sma = it; |
bf6830ad MS |
2155 | time_t sem_otime; |
2156 | ||
83aeb6e3 MS |
2157 | /* |
2158 | * The proc interface isn't aware of sem_lock(), it calls | |
2159 | * ipc_lock_object() directly (in sysvipc_find_ipc). | |
2160 | * In order to stay compatible with sem_lock(), we must wait until | |
2161 | * all simple semop() calls have left their critical regions. | |
2162 | */ | |
2163 | sem_wait_array(sma); | |
2164 | ||
bf6830ad | 2165 | sem_otime = get_semotime(sma); |
19b4946c MW |
2166 | |
2167 | return seq_printf(s, | |
b97e820f | 2168 | "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n", |
19b4946c | 2169 | sma->sem_perm.key, |
7ca7e564 | 2170 | sma->sem_perm.id, |
19b4946c MW |
2171 | sma->sem_perm.mode, |
2172 | sma->sem_nsems, | |
1efdb69b EB |
2173 | from_kuid_munged(user_ns, sma->sem_perm.uid), |
2174 | from_kgid_munged(user_ns, sma->sem_perm.gid), | |
2175 | from_kuid_munged(user_ns, sma->sem_perm.cuid), | |
2176 | from_kgid_munged(user_ns, sma->sem_perm.cgid), | |
bf6830ad | 2177 | sem_otime, |
19b4946c | 2178 | sma->sem_ctime); |
1da177e4 LT |
2179 | } |
2180 | #endif |