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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 */ |
1a82e9e1 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*/ | |
d12e1e50 | 102 | time_t sem_otime; /* candidate for sem_otime */ |
f5c936c0 | 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 | /* | |
758a6ba3 | 157 | * Locking: |
1da177e4 | 158 | * sem_undo.id_next, |
758a6ba3 | 159 | * sem_array.complex_count, |
1a82e9e1 | 160 | * sem_array.pending{_alter,_cont}, |
758a6ba3 | 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 | * | |
758a6ba3 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 | ||
f269f40a 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 | ||
53dad6d3 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 | ||
5e9d5275 MS |
255 | /* |
256 | * Wait until all currently ongoing simple ops have completed. | |
257 | * Caller must own sem_perm.lock. | |
258 | * New simple ops cannot start, because simple ops first check | |
259 | * that sem_perm.lock is free. | |
6d07b68c | 260 | * that a) sem_perm.lock is free and b) complex_count is 0. |
5e9d5275 MS |
261 | */ |
262 | static void sem_wait_array(struct sem_array *sma) | |
263 | { | |
264 | int i; | |
265 | struct sem *sem; | |
266 | ||
6d07b68c MS |
267 | if (sma->complex_count) { |
268 | /* The thread that increased sma->complex_count waited on | |
269 | * all sem->lock locks. Thus we don't need to wait again. | |
270 | */ | |
271 | return; | |
272 | } | |
273 | ||
5e9d5275 MS |
274 | for (i = 0; i < sma->sem_nsems; i++) { |
275 | sem = sma->sem_base + i; | |
276 | spin_unlock_wait(&sem->lock); | |
277 | } | |
278 | } | |
279 | ||
6062a8dc RR |
280 | /* |
281 | * If the request contains only one semaphore operation, and there are | |
282 | * no complex transactions pending, lock only the semaphore involved. | |
283 | * Otherwise, lock the entire semaphore array, since we either have | |
284 | * multiple semaphores in our own semops, or we need to look at | |
285 | * semaphores from other pending complex operations. | |
6062a8dc RR |
286 | */ |
287 | static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, | |
288 | int nsops) | |
289 | { | |
5e9d5275 | 290 | struct sem *sem; |
6062a8dc | 291 | |
5e9d5275 MS |
292 | if (nsops != 1) { |
293 | /* Complex operation - acquire a full lock */ | |
294 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 295 | |
5e9d5275 MS |
296 | /* And wait until all simple ops that are processed |
297 | * right now have dropped their locks. | |
6062a8dc | 298 | */ |
5e9d5275 MS |
299 | sem_wait_array(sma); |
300 | return -1; | |
301 | } | |
302 | ||
303 | /* | |
304 | * Only one semaphore affected - try to optimize locking. | |
305 | * The rules are: | |
306 | * - optimized locking is possible if no complex operation | |
307 | * is either enqueued or processed right now. | |
308 | * - The test for enqueued complex ops is simple: | |
309 | * sma->complex_count != 0 | |
310 | * - Testing for complex ops that are processed right now is | |
311 | * a bit more difficult. Complex ops acquire the full lock | |
312 | * and first wait that the running simple ops have completed. | |
313 | * (see above) | |
314 | * Thus: If we own a simple lock and the global lock is free | |
315 | * and complex_count is now 0, then it will stay 0 and | |
316 | * thus just locking sem->lock is sufficient. | |
317 | */ | |
318 | sem = sma->sem_base + sops->sem_num; | |
6062a8dc | 319 | |
5e9d5275 | 320 | if (sma->complex_count == 0) { |
6062a8dc | 321 | /* |
5e9d5275 MS |
322 | * It appears that no complex operation is around. |
323 | * Acquire the per-semaphore lock. | |
6062a8dc | 324 | */ |
5e9d5275 MS |
325 | spin_lock(&sem->lock); |
326 | ||
327 | /* Then check that the global lock is free */ | |
328 | if (!spin_is_locked(&sma->sem_perm.lock)) { | |
329 | /* spin_is_locked() is not a memory barrier */ | |
330 | smp_mb(); | |
331 | ||
332 | /* Now repeat the test of complex_count: | |
333 | * It can't change anymore until we drop sem->lock. | |
334 | * Thus: if is now 0, then it will stay 0. | |
335 | */ | |
336 | if (sma->complex_count == 0) { | |
337 | /* fast path successful! */ | |
338 | return sops->sem_num; | |
339 | } | |
6062a8dc | 340 | } |
5e9d5275 MS |
341 | spin_unlock(&sem->lock); |
342 | } | |
343 | ||
344 | /* slow path: acquire the full lock */ | |
345 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 346 | |
5e9d5275 MS |
347 | if (sma->complex_count == 0) { |
348 | /* False alarm: | |
349 | * There is no complex operation, thus we can switch | |
350 | * back to the fast path. | |
351 | */ | |
352 | spin_lock(&sem->lock); | |
353 | ipc_unlock_object(&sma->sem_perm); | |
354 | return sops->sem_num; | |
6062a8dc | 355 | } else { |
5e9d5275 MS |
356 | /* Not a false alarm, thus complete the sequence for a |
357 | * full lock. | |
6062a8dc | 358 | */ |
5e9d5275 MS |
359 | sem_wait_array(sma); |
360 | return -1; | |
6062a8dc | 361 | } |
6062a8dc RR |
362 | } |
363 | ||
364 | static inline void sem_unlock(struct sem_array *sma, int locknum) | |
365 | { | |
366 | if (locknum == -1) { | |
f269f40a | 367 | unmerge_queues(sma); |
cf9d5d78 | 368 | ipc_unlock_object(&sma->sem_perm); |
6062a8dc RR |
369 | } else { |
370 | struct sem *sem = sma->sem_base + locknum; | |
371 | spin_unlock(&sem->lock); | |
372 | } | |
6062a8dc RR |
373 | } |
374 | ||
3e148c79 | 375 | /* |
d9a605e4 | 376 | * sem_lock_(check_) routines are called in the paths where the rwsem |
3e148c79 | 377 | * is not held. |
321310ce LT |
378 | * |
379 | * The caller holds the RCU read lock. | |
3e148c79 | 380 | */ |
6062a8dc RR |
381 | static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, |
382 | int id, struct sembuf *sops, int nsops, int *locknum) | |
023a5355 | 383 | { |
c460b662 RR |
384 | struct kern_ipc_perm *ipcp; |
385 | struct sem_array *sma; | |
03f02c76 | 386 | |
c460b662 | 387 | ipcp = ipc_obtain_object(&sem_ids(ns), id); |
321310ce LT |
388 | if (IS_ERR(ipcp)) |
389 | return ERR_CAST(ipcp); | |
b1ed88b4 | 390 | |
6062a8dc RR |
391 | sma = container_of(ipcp, struct sem_array, sem_perm); |
392 | *locknum = sem_lock(sma, sops, nsops); | |
c460b662 RR |
393 | |
394 | /* ipc_rmid() may have already freed the ID while sem_lock | |
395 | * was spinning: verify that the structure is still valid | |
396 | */ | |
397 | if (!ipcp->deleted) | |
398 | return container_of(ipcp, struct sem_array, sem_perm); | |
399 | ||
6062a8dc | 400 | sem_unlock(sma, *locknum); |
321310ce | 401 | return ERR_PTR(-EINVAL); |
023a5355 ND |
402 | } |
403 | ||
16df3674 DB |
404 | static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id) |
405 | { | |
406 | struct kern_ipc_perm *ipcp = ipc_obtain_object(&sem_ids(ns), id); | |
407 | ||
408 | if (IS_ERR(ipcp)) | |
409 | return ERR_CAST(ipcp); | |
410 | ||
411 | return container_of(ipcp, struct sem_array, sem_perm); | |
412 | } | |
413 | ||
16df3674 DB |
414 | static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns, |
415 | int id) | |
416 | { | |
417 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id); | |
418 | ||
419 | if (IS_ERR(ipcp)) | |
420 | return ERR_CAST(ipcp); | |
b1ed88b4 | 421 | |
03f02c76 | 422 | return container_of(ipcp, struct sem_array, sem_perm); |
023a5355 ND |
423 | } |
424 | ||
6ff37972 PP |
425 | static inline void sem_lock_and_putref(struct sem_array *sma) |
426 | { | |
6062a8dc | 427 | sem_lock(sma, NULL, -1); |
53dad6d3 | 428 | ipc_rcu_putref(sma, ipc_rcu_free); |
6ff37972 PP |
429 | } |
430 | ||
7ca7e564 ND |
431 | static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) |
432 | { | |
433 | ipc_rmid(&sem_ids(ns), &s->sem_perm); | |
434 | } | |
435 | ||
1da177e4 LT |
436 | /* |
437 | * Lockless wakeup algorithm: | |
438 | * Without the check/retry algorithm a lockless wakeup is possible: | |
439 | * - queue.status is initialized to -EINTR before blocking. | |
440 | * - wakeup is performed by | |
1a82e9e1 | 441 | * * unlinking the queue entry from the pending list |
1da177e4 LT |
442 | * * setting queue.status to IN_WAKEUP |
443 | * This is the notification for the blocked thread that a | |
444 | * result value is imminent. | |
445 | * * call wake_up_process | |
446 | * * set queue.status to the final value. | |
447 | * - the previously blocked thread checks queue.status: | |
448 | * * if it's IN_WAKEUP, then it must wait until the value changes | |
449 | * * if it's not -EINTR, then the operation was completed by | |
450 | * update_queue. semtimedop can return queue.status without | |
5f921ae9 | 451 | * performing any operation on the sem array. |
1da177e4 LT |
452 | * * otherwise it must acquire the spinlock and check what's up. |
453 | * | |
454 | * The two-stage algorithm is necessary to protect against the following | |
455 | * races: | |
456 | * - if queue.status is set after wake_up_process, then the woken up idle | |
457 | * thread could race forward and try (and fail) to acquire sma->lock | |
458 | * before update_queue had a chance to set queue.status | |
459 | * - if queue.status is written before wake_up_process and if the | |
460 | * blocked process is woken up by a signal between writing | |
461 | * queue.status and the wake_up_process, then the woken up | |
462 | * process could return from semtimedop and die by calling | |
463 | * sys_exit before wake_up_process is called. Then wake_up_process | |
464 | * will oops, because the task structure is already invalid. | |
465 | * (yes, this happened on s390 with sysv msg). | |
466 | * | |
467 | */ | |
468 | #define IN_WAKEUP 1 | |
469 | ||
f4566f04 ND |
470 | /** |
471 | * newary - Create a new semaphore set | |
472 | * @ns: namespace | |
473 | * @params: ptr to the structure that contains key, semflg and nsems | |
474 | * | |
d9a605e4 | 475 | * Called with sem_ids.rwsem held (as a writer) |
f4566f04 ND |
476 | */ |
477 | ||
7748dbfa | 478 | static int newary(struct ipc_namespace *ns, struct ipc_params *params) |
1da177e4 LT |
479 | { |
480 | int id; | |
481 | int retval; | |
482 | struct sem_array *sma; | |
483 | int size; | |
7748dbfa ND |
484 | key_t key = params->key; |
485 | int nsems = params->u.nsems; | |
486 | int semflg = params->flg; | |
b97e820f | 487 | int i; |
1da177e4 LT |
488 | |
489 | if (!nsems) | |
490 | return -EINVAL; | |
e3893534 | 491 | if (ns->used_sems + nsems > ns->sc_semmns) |
1da177e4 LT |
492 | return -ENOSPC; |
493 | ||
494 | size = sizeof (*sma) + nsems * sizeof (struct sem); | |
495 | sma = ipc_rcu_alloc(size); | |
496 | if (!sma) { | |
497 | return -ENOMEM; | |
498 | } | |
499 | memset (sma, 0, size); | |
500 | ||
501 | sma->sem_perm.mode = (semflg & S_IRWXUGO); | |
502 | sma->sem_perm.key = key; | |
503 | ||
504 | sma->sem_perm.security = NULL; | |
505 | retval = security_sem_alloc(sma); | |
506 | if (retval) { | |
53dad6d3 | 507 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
508 | return retval; |
509 | } | |
510 | ||
e3893534 | 511 | id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); |
283bb7fa | 512 | if (id < 0) { |
53dad6d3 | 513 | ipc_rcu_putref(sma, sem_rcu_free); |
283bb7fa | 514 | return id; |
1da177e4 | 515 | } |
e3893534 | 516 | ns->used_sems += nsems; |
1da177e4 LT |
517 | |
518 | sma->sem_base = (struct sem *) &sma[1]; | |
b97e820f | 519 | |
6062a8dc | 520 | for (i = 0; i < nsems; i++) { |
1a82e9e1 MS |
521 | INIT_LIST_HEAD(&sma->sem_base[i].pending_alter); |
522 | INIT_LIST_HEAD(&sma->sem_base[i].pending_const); | |
6062a8dc RR |
523 | spin_lock_init(&sma->sem_base[i].lock); |
524 | } | |
b97e820f MS |
525 | |
526 | sma->complex_count = 0; | |
1a82e9e1 MS |
527 | INIT_LIST_HEAD(&sma->pending_alter); |
528 | INIT_LIST_HEAD(&sma->pending_const); | |
4daa28f6 | 529 | INIT_LIST_HEAD(&sma->list_id); |
1da177e4 LT |
530 | sma->sem_nsems = nsems; |
531 | sma->sem_ctime = get_seconds(); | |
6062a8dc | 532 | sem_unlock(sma, -1); |
6d49dab8 | 533 | rcu_read_unlock(); |
1da177e4 | 534 | |
7ca7e564 | 535 | return sma->sem_perm.id; |
1da177e4 LT |
536 | } |
537 | ||
7748dbfa | 538 | |
f4566f04 | 539 | /* |
d9a605e4 | 540 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 541 | */ |
03f02c76 | 542 | static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) |
7748dbfa | 543 | { |
03f02c76 ND |
544 | struct sem_array *sma; |
545 | ||
546 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
547 | return security_sem_associate(sma, semflg); | |
7748dbfa ND |
548 | } |
549 | ||
f4566f04 | 550 | /* |
d9a605e4 | 551 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 552 | */ |
03f02c76 ND |
553 | static inline int sem_more_checks(struct kern_ipc_perm *ipcp, |
554 | struct ipc_params *params) | |
7748dbfa | 555 | { |
03f02c76 ND |
556 | struct sem_array *sma; |
557 | ||
558 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
559 | if (params->u.nsems > sma->sem_nsems) | |
7748dbfa ND |
560 | return -EINVAL; |
561 | ||
562 | return 0; | |
563 | } | |
564 | ||
d5460c99 | 565 | SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) |
1da177e4 | 566 | { |
e3893534 | 567 | struct ipc_namespace *ns; |
7748dbfa ND |
568 | struct ipc_ops sem_ops; |
569 | struct ipc_params sem_params; | |
e3893534 KK |
570 | |
571 | ns = current->nsproxy->ipc_ns; | |
1da177e4 | 572 | |
e3893534 | 573 | if (nsems < 0 || nsems > ns->sc_semmsl) |
1da177e4 | 574 | return -EINVAL; |
7ca7e564 | 575 | |
7748dbfa ND |
576 | sem_ops.getnew = newary; |
577 | sem_ops.associate = sem_security; | |
578 | sem_ops.more_checks = sem_more_checks; | |
579 | ||
580 | sem_params.key = key; | |
581 | sem_params.flg = semflg; | |
582 | sem_params.u.nsems = nsems; | |
1da177e4 | 583 | |
7748dbfa | 584 | return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); |
1da177e4 LT |
585 | } |
586 | ||
78f5009c PM |
587 | /** |
588 | * perform_atomic_semop - Perform (if possible) a semaphore operation | |
758a6ba3 MS |
589 | * @sma: semaphore array |
590 | * @sops: array with operations that should be checked | |
78f5009c | 591 | * @nsops: number of operations |
758a6ba3 MS |
592 | * @un: undo array |
593 | * @pid: pid that did the change | |
594 | * | |
595 | * Returns 0 if the operation was possible. | |
596 | * Returns 1 if the operation is impossible, the caller must sleep. | |
597 | * Negative values are error codes. | |
1da177e4 | 598 | */ |
758a6ba3 | 599 | static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops, |
1da177e4 LT |
600 | int nsops, struct sem_undo *un, int pid) |
601 | { | |
602 | int result, sem_op; | |
603 | struct sembuf *sop; | |
604 | struct sem * curr; | |
605 | ||
606 | for (sop = sops; sop < sops + nsops; sop++) { | |
607 | curr = sma->sem_base + sop->sem_num; | |
608 | sem_op = sop->sem_op; | |
609 | result = curr->semval; | |
78f5009c | 610 | |
1da177e4 LT |
611 | if (!sem_op && result) |
612 | goto would_block; | |
613 | ||
614 | result += sem_op; | |
615 | if (result < 0) | |
616 | goto would_block; | |
617 | if (result > SEMVMX) | |
618 | goto out_of_range; | |
78f5009c | 619 | |
1da177e4 LT |
620 | if (sop->sem_flg & SEM_UNDO) { |
621 | int undo = un->semadj[sop->sem_num] - sem_op; | |
78f5009c | 622 | /* Exceeding the undo range is an error. */ |
1da177e4 LT |
623 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) |
624 | goto out_of_range; | |
78f5009c | 625 | un->semadj[sop->sem_num] = undo; |
1da177e4 | 626 | } |
78f5009c | 627 | |
1da177e4 LT |
628 | curr->semval = result; |
629 | } | |
630 | ||
631 | sop--; | |
632 | while (sop >= sops) { | |
633 | sma->sem_base[sop->sem_num].sempid = pid; | |
1da177e4 LT |
634 | sop--; |
635 | } | |
78f5009c | 636 | |
1da177e4 LT |
637 | return 0; |
638 | ||
639 | out_of_range: | |
640 | result = -ERANGE; | |
641 | goto undo; | |
642 | ||
643 | would_block: | |
644 | if (sop->sem_flg & IPC_NOWAIT) | |
645 | result = -EAGAIN; | |
646 | else | |
647 | result = 1; | |
648 | ||
649 | undo: | |
650 | sop--; | |
651 | while (sop >= sops) { | |
78f5009c PM |
652 | sem_op = sop->sem_op; |
653 | sma->sem_base[sop->sem_num].semval -= sem_op; | |
654 | if (sop->sem_flg & SEM_UNDO) | |
655 | un->semadj[sop->sem_num] += sem_op; | |
1da177e4 LT |
656 | sop--; |
657 | } | |
658 | ||
659 | return result; | |
660 | } | |
661 | ||
0a2b9d4c MS |
662 | /** wake_up_sem_queue_prepare(q, error): Prepare wake-up |
663 | * @q: queue entry that must be signaled | |
664 | * @error: Error value for the signal | |
665 | * | |
666 | * Prepare the wake-up of the queue entry q. | |
d4212093 | 667 | */ |
0a2b9d4c MS |
668 | static void wake_up_sem_queue_prepare(struct list_head *pt, |
669 | struct sem_queue *q, int error) | |
d4212093 | 670 | { |
0a2b9d4c MS |
671 | if (list_empty(pt)) { |
672 | /* | |
673 | * Hold preempt off so that we don't get preempted and have the | |
674 | * wakee busy-wait until we're scheduled back on. | |
675 | */ | |
676 | preempt_disable(); | |
677 | } | |
d4212093 | 678 | q->status = IN_WAKEUP; |
0a2b9d4c MS |
679 | q->pid = error; |
680 | ||
9f1bc2c9 | 681 | list_add_tail(&q->list, pt); |
0a2b9d4c MS |
682 | } |
683 | ||
684 | /** | |
685 | * wake_up_sem_queue_do(pt) - do the actual wake-up | |
686 | * @pt: list of tasks to be woken up | |
687 | * | |
688 | * Do the actual wake-up. | |
689 | * The function is called without any locks held, thus the semaphore array | |
690 | * could be destroyed already and the tasks can disappear as soon as the | |
691 | * status is set to the actual return code. | |
692 | */ | |
693 | static void wake_up_sem_queue_do(struct list_head *pt) | |
694 | { | |
695 | struct sem_queue *q, *t; | |
696 | int did_something; | |
697 | ||
698 | did_something = !list_empty(pt); | |
9f1bc2c9 | 699 | list_for_each_entry_safe(q, t, pt, list) { |
0a2b9d4c MS |
700 | wake_up_process(q->sleeper); |
701 | /* q can disappear immediately after writing q->status. */ | |
702 | smp_wmb(); | |
703 | q->status = q->pid; | |
704 | } | |
705 | if (did_something) | |
706 | preempt_enable(); | |
d4212093 NP |
707 | } |
708 | ||
b97e820f MS |
709 | static void unlink_queue(struct sem_array *sma, struct sem_queue *q) |
710 | { | |
711 | list_del(&q->list); | |
9f1bc2c9 | 712 | if (q->nsops > 1) |
b97e820f MS |
713 | sma->complex_count--; |
714 | } | |
715 | ||
fd5db422 MS |
716 | /** check_restart(sma, q) |
717 | * @sma: semaphore array | |
718 | * @q: the operation that just completed | |
719 | * | |
720 | * update_queue is O(N^2) when it restarts scanning the whole queue of | |
721 | * waiting operations. Therefore this function checks if the restart is | |
722 | * really necessary. It is called after a previously waiting operation | |
1a82e9e1 MS |
723 | * modified the array. |
724 | * Note that wait-for-zero operations are handled without restart. | |
fd5db422 MS |
725 | */ |
726 | static int check_restart(struct sem_array *sma, struct sem_queue *q) | |
727 | { | |
1a82e9e1 MS |
728 | /* pending complex alter operations are too difficult to analyse */ |
729 | if (!list_empty(&sma->pending_alter)) | |
fd5db422 MS |
730 | return 1; |
731 | ||
732 | /* we were a sleeping complex operation. Too difficult */ | |
733 | if (q->nsops > 1) | |
734 | return 1; | |
735 | ||
1a82e9e1 MS |
736 | /* It is impossible that someone waits for the new value: |
737 | * - complex operations always restart. | |
738 | * - wait-for-zero are handled seperately. | |
739 | * - q is a previously sleeping simple operation that | |
740 | * altered the array. It must be a decrement, because | |
741 | * simple increments never sleep. | |
742 | * - If there are older (higher priority) decrements | |
743 | * in the queue, then they have observed the original | |
744 | * semval value and couldn't proceed. The operation | |
745 | * decremented to value - thus they won't proceed either. | |
746 | */ | |
747 | return 0; | |
748 | } | |
fd5db422 | 749 | |
1a82e9e1 MS |
750 | /** |
751 | * wake_const_ops(sma, semnum, pt) - Wake up non-alter tasks | |
752 | * @sma: semaphore array. | |
753 | * @semnum: semaphore that was modified. | |
754 | * @pt: list head for the tasks that must be woken up. | |
755 | * | |
756 | * wake_const_ops must be called after a semaphore in a semaphore array | |
757 | * was set to 0. If complex const operations are pending, wake_const_ops must | |
758 | * be called with semnum = -1, as well as with the number of each modified | |
759 | * semaphore. | |
760 | * The tasks that must be woken up are added to @pt. The return code | |
761 | * is stored in q->pid. | |
762 | * The function returns 1 if at least one operation was completed successfully. | |
763 | */ | |
764 | static int wake_const_ops(struct sem_array *sma, int semnum, | |
765 | struct list_head *pt) | |
766 | { | |
767 | struct sem_queue *q; | |
768 | struct list_head *walk; | |
769 | struct list_head *pending_list; | |
770 | int semop_completed = 0; | |
771 | ||
772 | if (semnum == -1) | |
773 | pending_list = &sma->pending_const; | |
774 | else | |
775 | pending_list = &sma->sem_base[semnum].pending_const; | |
fd5db422 | 776 | |
1a82e9e1 MS |
777 | walk = pending_list->next; |
778 | while (walk != pending_list) { | |
779 | int error; | |
780 | ||
781 | q = container_of(walk, struct sem_queue, list); | |
782 | walk = walk->next; | |
783 | ||
758a6ba3 MS |
784 | error = perform_atomic_semop(sma, q->sops, q->nsops, |
785 | q->undo, q->pid); | |
1a82e9e1 MS |
786 | |
787 | if (error <= 0) { | |
788 | /* operation completed, remove from queue & wakeup */ | |
789 | ||
790 | unlink_queue(sma, q); | |
791 | ||
792 | wake_up_sem_queue_prepare(pt, q, error); | |
793 | if (error == 0) | |
794 | semop_completed = 1; | |
795 | } | |
796 | } | |
797 | return semop_completed; | |
798 | } | |
799 | ||
800 | /** | |
801 | * do_smart_wakeup_zero(sma, sops, nsops, pt) - wakeup all wait for zero tasks | |
802 | * @sma: semaphore array | |
803 | * @sops: operations that were performed | |
804 | * @nsops: number of operations | |
805 | * @pt: list head of the tasks that must be woken up. | |
806 | * | |
807 | * do_smart_wakeup_zero() checks all required queue for wait-for-zero | |
808 | * operations, based on the actual changes that were performed on the | |
809 | * semaphore array. | |
810 | * The function returns 1 if at least one operation was completed successfully. | |
811 | */ | |
812 | static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, | |
813 | int nsops, struct list_head *pt) | |
814 | { | |
815 | int i; | |
816 | int semop_completed = 0; | |
817 | int got_zero = 0; | |
818 | ||
819 | /* first: the per-semaphore queues, if known */ | |
820 | if (sops) { | |
821 | for (i = 0; i < nsops; i++) { | |
822 | int num = sops[i].sem_num; | |
823 | ||
824 | if (sma->sem_base[num].semval == 0) { | |
825 | got_zero = 1; | |
826 | semop_completed |= wake_const_ops(sma, num, pt); | |
827 | } | |
828 | } | |
829 | } else { | |
830 | /* | |
831 | * No sops means modified semaphores not known. | |
832 | * Assume all were changed. | |
fd5db422 | 833 | */ |
1a82e9e1 MS |
834 | for (i = 0; i < sma->sem_nsems; i++) { |
835 | if (sma->sem_base[i].semval == 0) { | |
836 | got_zero = 1; | |
837 | semop_completed |= wake_const_ops(sma, i, pt); | |
838 | } | |
839 | } | |
fd5db422 MS |
840 | } |
841 | /* | |
1a82e9e1 MS |
842 | * If one of the modified semaphores got 0, |
843 | * then check the global queue, too. | |
fd5db422 | 844 | */ |
1a82e9e1 MS |
845 | if (got_zero) |
846 | semop_completed |= wake_const_ops(sma, -1, pt); | |
fd5db422 | 847 | |
1a82e9e1 | 848 | return semop_completed; |
fd5db422 MS |
849 | } |
850 | ||
636c6be8 MS |
851 | |
852 | /** | |
853 | * update_queue(sma, semnum): Look for tasks that can be completed. | |
854 | * @sma: semaphore array. | |
855 | * @semnum: semaphore that was modified. | |
0a2b9d4c | 856 | * @pt: list head for the tasks that must be woken up. |
636c6be8 MS |
857 | * |
858 | * update_queue must be called after a semaphore in a semaphore array | |
9f1bc2c9 RR |
859 | * was modified. If multiple semaphores were modified, update_queue must |
860 | * be called with semnum = -1, as well as with the number of each modified | |
861 | * semaphore. | |
0a2b9d4c MS |
862 | * The tasks that must be woken up are added to @pt. The return code |
863 | * is stored in q->pid. | |
1a82e9e1 MS |
864 | * The function internally checks if const operations can now succeed. |
865 | * | |
0a2b9d4c | 866 | * The function return 1 if at least one semop was completed successfully. |
1da177e4 | 867 | */ |
0a2b9d4c | 868 | static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt) |
1da177e4 | 869 | { |
636c6be8 MS |
870 | struct sem_queue *q; |
871 | struct list_head *walk; | |
872 | struct list_head *pending_list; | |
0a2b9d4c | 873 | int semop_completed = 0; |
636c6be8 | 874 | |
9f1bc2c9 | 875 | if (semnum == -1) |
1a82e9e1 | 876 | pending_list = &sma->pending_alter; |
9f1bc2c9 | 877 | else |
1a82e9e1 | 878 | pending_list = &sma->sem_base[semnum].pending_alter; |
9cad200c NP |
879 | |
880 | again: | |
636c6be8 MS |
881 | walk = pending_list->next; |
882 | while (walk != pending_list) { | |
fd5db422 | 883 | int error, restart; |
636c6be8 | 884 | |
9f1bc2c9 | 885 | q = container_of(walk, struct sem_queue, list); |
636c6be8 | 886 | walk = walk->next; |
1da177e4 | 887 | |
d987f8b2 MS |
888 | /* If we are scanning the single sop, per-semaphore list of |
889 | * one semaphore and that semaphore is 0, then it is not | |
1a82e9e1 | 890 | * necessary to scan further: simple increments |
d987f8b2 MS |
891 | * that affect only one entry succeed immediately and cannot |
892 | * be in the per semaphore pending queue, and decrements | |
893 | * cannot be successful if the value is already 0. | |
894 | */ | |
1a82e9e1 | 895 | if (semnum != -1 && sma->sem_base[semnum].semval == 0) |
d987f8b2 MS |
896 | break; |
897 | ||
758a6ba3 | 898 | error = perform_atomic_semop(sma, q->sops, q->nsops, |
1da177e4 LT |
899 | q->undo, q->pid); |
900 | ||
901 | /* Does q->sleeper still need to sleep? */ | |
9cad200c NP |
902 | if (error > 0) |
903 | continue; | |
904 | ||
b97e820f | 905 | unlink_queue(sma, q); |
9cad200c | 906 | |
0a2b9d4c | 907 | if (error) { |
fd5db422 | 908 | restart = 0; |
0a2b9d4c MS |
909 | } else { |
910 | semop_completed = 1; | |
1a82e9e1 | 911 | do_smart_wakeup_zero(sma, q->sops, q->nsops, pt); |
fd5db422 | 912 | restart = check_restart(sma, q); |
0a2b9d4c | 913 | } |
fd5db422 | 914 | |
0a2b9d4c | 915 | wake_up_sem_queue_prepare(pt, q, error); |
fd5db422 | 916 | if (restart) |
9cad200c | 917 | goto again; |
1da177e4 | 918 | } |
0a2b9d4c | 919 | return semop_completed; |
1da177e4 LT |
920 | } |
921 | ||
0e8c6656 MS |
922 | /** |
923 | * set_semotime(sma, sops) - set sem_otime | |
924 | * @sma: semaphore array | |
925 | * @sops: operations that modified the array, may be NULL | |
926 | * | |
927 | * sem_otime is replicated to avoid cache line trashing. | |
928 | * This function sets one instance to the current time. | |
929 | */ | |
930 | static void set_semotime(struct sem_array *sma, struct sembuf *sops) | |
931 | { | |
932 | if (sops == NULL) { | |
933 | sma->sem_base[0].sem_otime = get_seconds(); | |
934 | } else { | |
935 | sma->sem_base[sops[0].sem_num].sem_otime = | |
936 | get_seconds(); | |
937 | } | |
938 | } | |
939 | ||
0a2b9d4c MS |
940 | /** |
941 | * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue | |
fd5db422 MS |
942 | * @sma: semaphore array |
943 | * @sops: operations that were performed | |
944 | * @nsops: number of operations | |
0a2b9d4c MS |
945 | * @otime: force setting otime |
946 | * @pt: list head of the tasks that must be woken up. | |
fd5db422 | 947 | * |
1a82e9e1 MS |
948 | * do_smart_update() does the required calls to update_queue and wakeup_zero, |
949 | * based on the actual changes that were performed on the semaphore array. | |
0a2b9d4c MS |
950 | * Note that the function does not do the actual wake-up: the caller is |
951 | * responsible for calling wake_up_sem_queue_do(@pt). | |
952 | * It is safe to perform this call after dropping all locks. | |
fd5db422 | 953 | */ |
0a2b9d4c MS |
954 | static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops, |
955 | int otime, struct list_head *pt) | |
fd5db422 MS |
956 | { |
957 | int i; | |
958 | ||
1a82e9e1 MS |
959 | otime |= do_smart_wakeup_zero(sma, sops, nsops, pt); |
960 | ||
f269f40a MS |
961 | if (!list_empty(&sma->pending_alter)) { |
962 | /* semaphore array uses the global queue - just process it. */ | |
963 | otime |= update_queue(sma, -1, pt); | |
964 | } else { | |
965 | if (!sops) { | |
966 | /* | |
967 | * No sops, thus the modified semaphores are not | |
968 | * known. Check all. | |
969 | */ | |
970 | for (i = 0; i < sma->sem_nsems; i++) | |
971 | otime |= update_queue(sma, i, pt); | |
972 | } else { | |
973 | /* | |
974 | * Check the semaphores that were increased: | |
975 | * - No complex ops, thus all sleeping ops are | |
976 | * decrease. | |
977 | * - if we decreased the value, then any sleeping | |
978 | * semaphore ops wont be able to run: If the | |
979 | * previous value was too small, then the new | |
980 | * value will be too small, too. | |
981 | */ | |
982 | for (i = 0; i < nsops; i++) { | |
983 | if (sops[i].sem_op > 0) { | |
984 | otime |= update_queue(sma, | |
985 | sops[i].sem_num, pt); | |
986 | } | |
ab465df9 | 987 | } |
9f1bc2c9 | 988 | } |
fd5db422 | 989 | } |
0e8c6656 MS |
990 | if (otime) |
991 | set_semotime(sma, sops); | |
fd5db422 MS |
992 | } |
993 | ||
1da177e4 LT |
994 | /* The following counts are associated to each semaphore: |
995 | * semncnt number of tasks waiting on semval being nonzero | |
996 | * semzcnt number of tasks waiting on semval being zero | |
997 | * This model assumes that a task waits on exactly one semaphore. | |
998 | * Since semaphore operations are to be performed atomically, tasks actually | |
999 | * wait on a whole sequence of semaphores simultaneously. | |
1000 | * The counts we return here are a rough approximation, but still | |
1001 | * warrant that semncnt+semzcnt>0 if the task is on the pending queue. | |
1002 | */ | |
1003 | static int count_semncnt (struct sem_array * sma, ushort semnum) | |
1004 | { | |
1005 | int semncnt; | |
1006 | struct sem_queue * q; | |
1007 | ||
1008 | semncnt = 0; | |
1a82e9e1 | 1009 | list_for_each_entry(q, &sma->sem_base[semnum].pending_alter, list) { |
de2657f9 RR |
1010 | struct sembuf * sops = q->sops; |
1011 | BUG_ON(sops->sem_num != semnum); | |
1012 | if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT)) | |
1013 | semncnt++; | |
1014 | } | |
1015 | ||
1a82e9e1 | 1016 | list_for_each_entry(q, &sma->pending_alter, list) { |
1da177e4 LT |
1017 | struct sembuf * sops = q->sops; |
1018 | int nsops = q->nsops; | |
1019 | int i; | |
1020 | for (i = 0; i < nsops; i++) | |
1021 | if (sops[i].sem_num == semnum | |
1022 | && (sops[i].sem_op < 0) | |
1023 | && !(sops[i].sem_flg & IPC_NOWAIT)) | |
1024 | semncnt++; | |
1025 | } | |
1026 | return semncnt; | |
1027 | } | |
a1193f8e | 1028 | |
1da177e4 LT |
1029 | static int count_semzcnt (struct sem_array * sma, ushort semnum) |
1030 | { | |
1031 | int semzcnt; | |
1032 | struct sem_queue * q; | |
1033 | ||
1034 | semzcnt = 0; | |
1a82e9e1 | 1035 | list_for_each_entry(q, &sma->sem_base[semnum].pending_const, list) { |
ebc2e5e6 RR |
1036 | struct sembuf * sops = q->sops; |
1037 | BUG_ON(sops->sem_num != semnum); | |
1038 | if ((sops->sem_op == 0) && !(sops->sem_flg & IPC_NOWAIT)) | |
1039 | semzcnt++; | |
1040 | } | |
1041 | ||
1a82e9e1 | 1042 | list_for_each_entry(q, &sma->pending_const, list) { |
1da177e4 LT |
1043 | struct sembuf * sops = q->sops; |
1044 | int nsops = q->nsops; | |
1045 | int i; | |
1046 | for (i = 0; i < nsops; i++) | |
1047 | if (sops[i].sem_num == semnum | |
1048 | && (sops[i].sem_op == 0) | |
1049 | && !(sops[i].sem_flg & IPC_NOWAIT)) | |
1050 | semzcnt++; | |
1051 | } | |
1052 | return semzcnt; | |
1053 | } | |
1054 | ||
d9a605e4 DB |
1055 | /* Free a semaphore set. freeary() is called with sem_ids.rwsem locked |
1056 | * as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem | |
3e148c79 | 1057 | * remains locked on exit. |
1da177e4 | 1058 | */ |
01b8b07a | 1059 | static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
1da177e4 | 1060 | { |
380af1b3 MS |
1061 | struct sem_undo *un, *tu; |
1062 | struct sem_queue *q, *tq; | |
01b8b07a | 1063 | struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
0a2b9d4c | 1064 | struct list_head tasks; |
9f1bc2c9 | 1065 | int i; |
1da177e4 | 1066 | |
380af1b3 | 1067 | /* Free the existing undo structures for this semaphore set. */ |
cf9d5d78 | 1068 | ipc_assert_locked_object(&sma->sem_perm); |
380af1b3 MS |
1069 | list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { |
1070 | list_del(&un->list_id); | |
1071 | spin_lock(&un->ulp->lock); | |
1da177e4 | 1072 | un->semid = -1; |
380af1b3 MS |
1073 | list_del_rcu(&un->list_proc); |
1074 | spin_unlock(&un->ulp->lock); | |
693a8b6e | 1075 | kfree_rcu(un, rcu); |
380af1b3 | 1076 | } |
1da177e4 LT |
1077 | |
1078 | /* Wake up all pending processes and let them fail with EIDRM. */ | |
0a2b9d4c | 1079 | INIT_LIST_HEAD(&tasks); |
1a82e9e1 MS |
1080 | list_for_each_entry_safe(q, tq, &sma->pending_const, list) { |
1081 | unlink_queue(sma, q); | |
1082 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1083 | } | |
1084 | ||
1085 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { | |
b97e820f | 1086 | unlink_queue(sma, q); |
0a2b9d4c | 1087 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); |
1da177e4 | 1088 | } |
9f1bc2c9 RR |
1089 | for (i = 0; i < sma->sem_nsems; i++) { |
1090 | struct sem *sem = sma->sem_base + i; | |
1a82e9e1 MS |
1091 | list_for_each_entry_safe(q, tq, &sem->pending_const, list) { |
1092 | unlink_queue(sma, q); | |
1093 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1094 | } | |
1095 | list_for_each_entry_safe(q, tq, &sem->pending_alter, list) { | |
9f1bc2c9 RR |
1096 | unlink_queue(sma, q); |
1097 | wake_up_sem_queue_prepare(&tasks, q, -EIDRM); | |
1098 | } | |
1099 | } | |
1da177e4 | 1100 | |
7ca7e564 ND |
1101 | /* Remove the semaphore set from the IDR */ |
1102 | sem_rmid(ns, sma); | |
6062a8dc | 1103 | sem_unlock(sma, -1); |
6d49dab8 | 1104 | rcu_read_unlock(); |
1da177e4 | 1105 | |
0a2b9d4c | 1106 | wake_up_sem_queue_do(&tasks); |
e3893534 | 1107 | ns->used_sems -= sma->sem_nsems; |
53dad6d3 | 1108 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1109 | } |
1110 | ||
1111 | static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) | |
1112 | { | |
1113 | switch(version) { | |
1114 | case IPC_64: | |
1115 | return copy_to_user(buf, in, sizeof(*in)); | |
1116 | case IPC_OLD: | |
1117 | { | |
1118 | struct semid_ds out; | |
1119 | ||
982f7c2b DR |
1120 | memset(&out, 0, sizeof(out)); |
1121 | ||
1da177e4 LT |
1122 | ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm); |
1123 | ||
1124 | out.sem_otime = in->sem_otime; | |
1125 | out.sem_ctime = in->sem_ctime; | |
1126 | out.sem_nsems = in->sem_nsems; | |
1127 | ||
1128 | return copy_to_user(buf, &out, sizeof(out)); | |
1129 | } | |
1130 | default: | |
1131 | return -EINVAL; | |
1132 | } | |
1133 | } | |
1134 | ||
d12e1e50 MS |
1135 | static time_t get_semotime(struct sem_array *sma) |
1136 | { | |
1137 | int i; | |
1138 | time_t res; | |
1139 | ||
1140 | res = sma->sem_base[0].sem_otime; | |
1141 | for (i = 1; i < sma->sem_nsems; i++) { | |
1142 | time_t to = sma->sem_base[i].sem_otime; | |
1143 | ||
1144 | if (to > res) | |
1145 | res = to; | |
1146 | } | |
1147 | return res; | |
1148 | } | |
1149 | ||
4b9fcb0e | 1150 | static int semctl_nolock(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1151 | int cmd, int version, void __user *p) |
1da177e4 | 1152 | { |
e5cc9c7b | 1153 | int err; |
1da177e4 LT |
1154 | struct sem_array *sma; |
1155 | ||
1156 | switch(cmd) { | |
1157 | case IPC_INFO: | |
1158 | case SEM_INFO: | |
1159 | { | |
1160 | struct seminfo seminfo; | |
1161 | int max_id; | |
1162 | ||
1163 | err = security_sem_semctl(NULL, cmd); | |
1164 | if (err) | |
1165 | return err; | |
1166 | ||
1167 | memset(&seminfo,0,sizeof(seminfo)); | |
e3893534 KK |
1168 | seminfo.semmni = ns->sc_semmni; |
1169 | seminfo.semmns = ns->sc_semmns; | |
1170 | seminfo.semmsl = ns->sc_semmsl; | |
1171 | seminfo.semopm = ns->sc_semopm; | |
1da177e4 LT |
1172 | seminfo.semvmx = SEMVMX; |
1173 | seminfo.semmnu = SEMMNU; | |
1174 | seminfo.semmap = SEMMAP; | |
1175 | seminfo.semume = SEMUME; | |
d9a605e4 | 1176 | down_read(&sem_ids(ns).rwsem); |
1da177e4 | 1177 | if (cmd == SEM_INFO) { |
e3893534 KK |
1178 | seminfo.semusz = sem_ids(ns).in_use; |
1179 | seminfo.semaem = ns->used_sems; | |
1da177e4 LT |
1180 | } else { |
1181 | seminfo.semusz = SEMUSZ; | |
1182 | seminfo.semaem = SEMAEM; | |
1183 | } | |
7ca7e564 | 1184 | max_id = ipc_get_maxid(&sem_ids(ns)); |
d9a605e4 | 1185 | up_read(&sem_ids(ns).rwsem); |
e1fd1f49 | 1186 | if (copy_to_user(p, &seminfo, sizeof(struct seminfo))) |
1da177e4 LT |
1187 | return -EFAULT; |
1188 | return (max_id < 0) ? 0: max_id; | |
1189 | } | |
4b9fcb0e | 1190 | case IPC_STAT: |
1da177e4 LT |
1191 | case SEM_STAT: |
1192 | { | |
1193 | struct semid64_ds tbuf; | |
16df3674 DB |
1194 | int id = 0; |
1195 | ||
1196 | memset(&tbuf, 0, sizeof(tbuf)); | |
1da177e4 | 1197 | |
941b0304 | 1198 | rcu_read_lock(); |
4b9fcb0e | 1199 | if (cmd == SEM_STAT) { |
16df3674 DB |
1200 | sma = sem_obtain_object(ns, semid); |
1201 | if (IS_ERR(sma)) { | |
1202 | err = PTR_ERR(sma); | |
1203 | goto out_unlock; | |
1204 | } | |
4b9fcb0e PP |
1205 | id = sma->sem_perm.id; |
1206 | } else { | |
16df3674 DB |
1207 | sma = sem_obtain_object_check(ns, semid); |
1208 | if (IS_ERR(sma)) { | |
1209 | err = PTR_ERR(sma); | |
1210 | goto out_unlock; | |
1211 | } | |
4b9fcb0e | 1212 | } |
1da177e4 LT |
1213 | |
1214 | err = -EACCES; | |
b0e77598 | 1215 | if (ipcperms(ns, &sma->sem_perm, S_IRUGO)) |
1da177e4 LT |
1216 | goto out_unlock; |
1217 | ||
1218 | err = security_sem_semctl(sma, cmd); | |
1219 | if (err) | |
1220 | goto out_unlock; | |
1221 | ||
1da177e4 | 1222 | kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); |
d12e1e50 MS |
1223 | tbuf.sem_otime = get_semotime(sma); |
1224 | tbuf.sem_ctime = sma->sem_ctime; | |
1225 | tbuf.sem_nsems = sma->sem_nsems; | |
16df3674 | 1226 | rcu_read_unlock(); |
e1fd1f49 | 1227 | if (copy_semid_to_user(p, &tbuf, version)) |
1da177e4 LT |
1228 | return -EFAULT; |
1229 | return id; | |
1230 | } | |
1231 | default: | |
1232 | return -EINVAL; | |
1233 | } | |
1da177e4 | 1234 | out_unlock: |
16df3674 | 1235 | rcu_read_unlock(); |
1da177e4 LT |
1236 | return err; |
1237 | } | |
1238 | ||
e1fd1f49 AV |
1239 | static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, |
1240 | unsigned long arg) | |
1241 | { | |
1242 | struct sem_undo *un; | |
1243 | struct sem_array *sma; | |
1244 | struct sem* curr; | |
1245 | int err; | |
e1fd1f49 AV |
1246 | struct list_head tasks; |
1247 | int val; | |
1248 | #if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN) | |
1249 | /* big-endian 64bit */ | |
1250 | val = arg >> 32; | |
1251 | #else | |
1252 | /* 32bit or little-endian 64bit */ | |
1253 | val = arg; | |
1254 | #endif | |
1255 | ||
6062a8dc RR |
1256 | if (val > SEMVMX || val < 0) |
1257 | return -ERANGE; | |
e1fd1f49 AV |
1258 | |
1259 | INIT_LIST_HEAD(&tasks); | |
e1fd1f49 | 1260 | |
6062a8dc RR |
1261 | rcu_read_lock(); |
1262 | sma = sem_obtain_object_check(ns, semid); | |
1263 | if (IS_ERR(sma)) { | |
1264 | rcu_read_unlock(); | |
1265 | return PTR_ERR(sma); | |
1266 | } | |
1267 | ||
1268 | if (semnum < 0 || semnum >= sma->sem_nsems) { | |
1269 | rcu_read_unlock(); | |
1270 | return -EINVAL; | |
1271 | } | |
1272 | ||
1273 | ||
1274 | if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) { | |
1275 | rcu_read_unlock(); | |
1276 | return -EACCES; | |
1277 | } | |
e1fd1f49 AV |
1278 | |
1279 | err = security_sem_semctl(sma, SETVAL); | |
6062a8dc RR |
1280 | if (err) { |
1281 | rcu_read_unlock(); | |
1282 | return -EACCES; | |
1283 | } | |
e1fd1f49 | 1284 | |
6062a8dc | 1285 | sem_lock(sma, NULL, -1); |
e1fd1f49 | 1286 | |
0f3d2b01 | 1287 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1288 | sem_unlock(sma, -1); |
1289 | rcu_read_unlock(); | |
1290 | return -EIDRM; | |
1291 | } | |
1292 | ||
e1fd1f49 AV |
1293 | curr = &sma->sem_base[semnum]; |
1294 | ||
cf9d5d78 | 1295 | ipc_assert_locked_object(&sma->sem_perm); |
e1fd1f49 AV |
1296 | list_for_each_entry(un, &sma->list_id, list_id) |
1297 | un->semadj[semnum] = 0; | |
1298 | ||
1299 | curr->semval = val; | |
1300 | curr->sempid = task_tgid_vnr(current); | |
1301 | sma->sem_ctime = get_seconds(); | |
1302 | /* maybe some queued-up processes were waiting for this */ | |
1303 | do_smart_update(sma, NULL, 0, 0, &tasks); | |
6062a8dc | 1304 | sem_unlock(sma, -1); |
6d49dab8 | 1305 | rcu_read_unlock(); |
e1fd1f49 | 1306 | wake_up_sem_queue_do(&tasks); |
6062a8dc | 1307 | return 0; |
e1fd1f49 AV |
1308 | } |
1309 | ||
e3893534 | 1310 | static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, |
e1fd1f49 | 1311 | int cmd, void __user *p) |
1da177e4 LT |
1312 | { |
1313 | struct sem_array *sma; | |
1314 | struct sem* curr; | |
16df3674 | 1315 | int err, nsems; |
1da177e4 LT |
1316 | ushort fast_sem_io[SEMMSL_FAST]; |
1317 | ushort* sem_io = fast_sem_io; | |
0a2b9d4c | 1318 | struct list_head tasks; |
1da177e4 | 1319 | |
16df3674 DB |
1320 | INIT_LIST_HEAD(&tasks); |
1321 | ||
1322 | rcu_read_lock(); | |
1323 | sma = sem_obtain_object_check(ns, semid); | |
1324 | if (IS_ERR(sma)) { | |
1325 | rcu_read_unlock(); | |
023a5355 | 1326 | return PTR_ERR(sma); |
16df3674 | 1327 | } |
1da177e4 LT |
1328 | |
1329 | nsems = sma->sem_nsems; | |
1330 | ||
1da177e4 | 1331 | err = -EACCES; |
c728b9c8 LT |
1332 | if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO)) |
1333 | goto out_rcu_wakeup; | |
1da177e4 LT |
1334 | |
1335 | err = security_sem_semctl(sma, cmd); | |
c728b9c8 LT |
1336 | if (err) |
1337 | goto out_rcu_wakeup; | |
1da177e4 LT |
1338 | |
1339 | err = -EACCES; | |
1340 | switch (cmd) { | |
1341 | case GETALL: | |
1342 | { | |
e1fd1f49 | 1343 | ushort __user *array = p; |
1da177e4 LT |
1344 | int i; |
1345 | ||
ce857229 | 1346 | sem_lock(sma, NULL, -1); |
0f3d2b01 | 1347 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1348 | err = -EIDRM; |
1349 | goto out_unlock; | |
1350 | } | |
1da177e4 | 1351 | if(nsems > SEMMSL_FAST) { |
ce857229 | 1352 | if (!ipc_rcu_getref(sma)) { |
ce857229 | 1353 | err = -EIDRM; |
6e224f94 | 1354 | goto out_unlock; |
ce857229 AV |
1355 | } |
1356 | sem_unlock(sma, -1); | |
6d49dab8 | 1357 | rcu_read_unlock(); |
1da177e4 LT |
1358 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
1359 | if(sem_io == NULL) { | |
53dad6d3 | 1360 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1361 | return -ENOMEM; |
1362 | } | |
1363 | ||
4091fd94 | 1364 | rcu_read_lock(); |
6ff37972 | 1365 | sem_lock_and_putref(sma); |
0f3d2b01 | 1366 | if (!ipc_valid_object(&sma->sem_perm)) { |
1da177e4 | 1367 | err = -EIDRM; |
6e224f94 | 1368 | goto out_unlock; |
1da177e4 | 1369 | } |
ce857229 | 1370 | } |
1da177e4 LT |
1371 | for (i = 0; i < sma->sem_nsems; i++) |
1372 | sem_io[i] = sma->sem_base[i].semval; | |
6062a8dc | 1373 | sem_unlock(sma, -1); |
6d49dab8 | 1374 | rcu_read_unlock(); |
1da177e4 LT |
1375 | err = 0; |
1376 | if(copy_to_user(array, sem_io, nsems*sizeof(ushort))) | |
1377 | err = -EFAULT; | |
1378 | goto out_free; | |
1379 | } | |
1380 | case SETALL: | |
1381 | { | |
1382 | int i; | |
1383 | struct sem_undo *un; | |
1384 | ||
6062a8dc | 1385 | if (!ipc_rcu_getref(sma)) { |
6e224f94 MS |
1386 | err = -EIDRM; |
1387 | goto out_rcu_wakeup; | |
6062a8dc | 1388 | } |
16df3674 | 1389 | rcu_read_unlock(); |
1da177e4 LT |
1390 | |
1391 | if(nsems > SEMMSL_FAST) { | |
1392 | sem_io = ipc_alloc(sizeof(ushort)*nsems); | |
1393 | if(sem_io == NULL) { | |
53dad6d3 | 1394 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1395 | return -ENOMEM; |
1396 | } | |
1397 | } | |
1398 | ||
e1fd1f49 | 1399 | if (copy_from_user (sem_io, p, nsems*sizeof(ushort))) { |
53dad6d3 | 1400 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1401 | err = -EFAULT; |
1402 | goto out_free; | |
1403 | } | |
1404 | ||
1405 | for (i = 0; i < nsems; i++) { | |
1406 | if (sem_io[i] > SEMVMX) { | |
53dad6d3 | 1407 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1408 | err = -ERANGE; |
1409 | goto out_free; | |
1410 | } | |
1411 | } | |
4091fd94 | 1412 | rcu_read_lock(); |
6ff37972 | 1413 | sem_lock_and_putref(sma); |
0f3d2b01 | 1414 | if (!ipc_valid_object(&sma->sem_perm)) { |
1da177e4 | 1415 | err = -EIDRM; |
6e224f94 | 1416 | goto out_unlock; |
1da177e4 LT |
1417 | } |
1418 | ||
1419 | for (i = 0; i < nsems; i++) | |
1420 | sma->sem_base[i].semval = sem_io[i]; | |
4daa28f6 | 1421 | |
cf9d5d78 | 1422 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1423 | list_for_each_entry(un, &sma->list_id, list_id) { |
1da177e4 LT |
1424 | for (i = 0; i < nsems; i++) |
1425 | un->semadj[i] = 0; | |
4daa28f6 | 1426 | } |
1da177e4 LT |
1427 | sma->sem_ctime = get_seconds(); |
1428 | /* maybe some queued-up processes were waiting for this */ | |
0a2b9d4c | 1429 | do_smart_update(sma, NULL, 0, 0, &tasks); |
1da177e4 LT |
1430 | err = 0; |
1431 | goto out_unlock; | |
1432 | } | |
e1fd1f49 | 1433 | /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */ |
1da177e4 LT |
1434 | } |
1435 | err = -EINVAL; | |
c728b9c8 LT |
1436 | if (semnum < 0 || semnum >= nsems) |
1437 | goto out_rcu_wakeup; | |
1da177e4 | 1438 | |
6062a8dc | 1439 | sem_lock(sma, NULL, -1); |
0f3d2b01 | 1440 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1441 | err = -EIDRM; |
1442 | goto out_unlock; | |
1443 | } | |
1da177e4 LT |
1444 | curr = &sma->sem_base[semnum]; |
1445 | ||
1446 | switch (cmd) { | |
1447 | case GETVAL: | |
1448 | err = curr->semval; | |
1449 | goto out_unlock; | |
1450 | case GETPID: | |
1451 | err = curr->sempid; | |
1452 | goto out_unlock; | |
1453 | case GETNCNT: | |
1454 | err = count_semncnt(sma,semnum); | |
1455 | goto out_unlock; | |
1456 | case GETZCNT: | |
1457 | err = count_semzcnt(sma,semnum); | |
1458 | goto out_unlock; | |
1da177e4 | 1459 | } |
16df3674 | 1460 | |
1da177e4 | 1461 | out_unlock: |
6062a8dc | 1462 | sem_unlock(sma, -1); |
c728b9c8 | 1463 | out_rcu_wakeup: |
6d49dab8 | 1464 | rcu_read_unlock(); |
0a2b9d4c | 1465 | wake_up_sem_queue_do(&tasks); |
1da177e4 LT |
1466 | out_free: |
1467 | if(sem_io != fast_sem_io) | |
1468 | ipc_free(sem_io, sizeof(ushort)*nsems); | |
1469 | return err; | |
1470 | } | |
1471 | ||
016d7132 PP |
1472 | static inline unsigned long |
1473 | copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) | |
1da177e4 LT |
1474 | { |
1475 | switch(version) { | |
1476 | case IPC_64: | |
016d7132 | 1477 | if (copy_from_user(out, buf, sizeof(*out))) |
1da177e4 | 1478 | return -EFAULT; |
1da177e4 | 1479 | return 0; |
1da177e4 LT |
1480 | case IPC_OLD: |
1481 | { | |
1482 | struct semid_ds tbuf_old; | |
1483 | ||
1484 | if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) | |
1485 | return -EFAULT; | |
1486 | ||
016d7132 PP |
1487 | out->sem_perm.uid = tbuf_old.sem_perm.uid; |
1488 | out->sem_perm.gid = tbuf_old.sem_perm.gid; | |
1489 | out->sem_perm.mode = tbuf_old.sem_perm.mode; | |
1da177e4 LT |
1490 | |
1491 | return 0; | |
1492 | } | |
1493 | default: | |
1494 | return -EINVAL; | |
1495 | } | |
1496 | } | |
1497 | ||
522bb2a2 | 1498 | /* |
d9a605e4 | 1499 | * This function handles some semctl commands which require the rwsem |
522bb2a2 | 1500 | * to be held in write mode. |
d9a605e4 | 1501 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
522bb2a2 | 1502 | */ |
21a4826a | 1503 | static int semctl_down(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1504 | int cmd, int version, void __user *p) |
1da177e4 LT |
1505 | { |
1506 | struct sem_array *sma; | |
1507 | int err; | |
016d7132 | 1508 | struct semid64_ds semid64; |
1da177e4 LT |
1509 | struct kern_ipc_perm *ipcp; |
1510 | ||
1511 | if(cmd == IPC_SET) { | |
e1fd1f49 | 1512 | if (copy_semid_from_user(&semid64, p, version)) |
1da177e4 | 1513 | return -EFAULT; |
1da177e4 | 1514 | } |
073115d6 | 1515 | |
d9a605e4 | 1516 | down_write(&sem_ids(ns).rwsem); |
7b4cc5d8 DB |
1517 | rcu_read_lock(); |
1518 | ||
16df3674 DB |
1519 | ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd, |
1520 | &semid64.sem_perm, 0); | |
7b4cc5d8 DB |
1521 | if (IS_ERR(ipcp)) { |
1522 | err = PTR_ERR(ipcp); | |
7b4cc5d8 DB |
1523 | goto out_unlock1; |
1524 | } | |
073115d6 | 1525 | |
a5f75e7f | 1526 | sma = container_of(ipcp, struct sem_array, sem_perm); |
1da177e4 LT |
1527 | |
1528 | err = security_sem_semctl(sma, cmd); | |
7b4cc5d8 DB |
1529 | if (err) |
1530 | goto out_unlock1; | |
1da177e4 | 1531 | |
7b4cc5d8 | 1532 | switch (cmd) { |
1da177e4 | 1533 | case IPC_RMID: |
6062a8dc | 1534 | sem_lock(sma, NULL, -1); |
7b4cc5d8 | 1535 | /* freeary unlocks the ipc object and rcu */ |
01b8b07a | 1536 | freeary(ns, ipcp); |
522bb2a2 | 1537 | goto out_up; |
1da177e4 | 1538 | case IPC_SET: |
6062a8dc | 1539 | sem_lock(sma, NULL, -1); |
1efdb69b EB |
1540 | err = ipc_update_perm(&semid64.sem_perm, ipcp); |
1541 | if (err) | |
7b4cc5d8 | 1542 | goto out_unlock0; |
1da177e4 | 1543 | sma->sem_ctime = get_seconds(); |
1da177e4 LT |
1544 | break; |
1545 | default: | |
1da177e4 | 1546 | err = -EINVAL; |
7b4cc5d8 | 1547 | goto out_unlock1; |
1da177e4 | 1548 | } |
1da177e4 | 1549 | |
7b4cc5d8 | 1550 | out_unlock0: |
6062a8dc | 1551 | sem_unlock(sma, -1); |
7b4cc5d8 | 1552 | out_unlock1: |
6d49dab8 | 1553 | rcu_read_unlock(); |
522bb2a2 | 1554 | out_up: |
d9a605e4 | 1555 | up_write(&sem_ids(ns).rwsem); |
1da177e4 LT |
1556 | return err; |
1557 | } | |
1558 | ||
e1fd1f49 | 1559 | SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) |
1da177e4 | 1560 | { |
1da177e4 | 1561 | int version; |
e3893534 | 1562 | struct ipc_namespace *ns; |
e1fd1f49 | 1563 | void __user *p = (void __user *)arg; |
1da177e4 LT |
1564 | |
1565 | if (semid < 0) | |
1566 | return -EINVAL; | |
1567 | ||
1568 | version = ipc_parse_version(&cmd); | |
e3893534 | 1569 | ns = current->nsproxy->ipc_ns; |
1da177e4 LT |
1570 | |
1571 | switch(cmd) { | |
1572 | case IPC_INFO: | |
1573 | case SEM_INFO: | |
4b9fcb0e | 1574 | case IPC_STAT: |
1da177e4 | 1575 | case SEM_STAT: |
e1fd1f49 | 1576 | return semctl_nolock(ns, semid, cmd, version, p); |
1da177e4 LT |
1577 | case GETALL: |
1578 | case GETVAL: | |
1579 | case GETPID: | |
1580 | case GETNCNT: | |
1581 | case GETZCNT: | |
1da177e4 | 1582 | case SETALL: |
e1fd1f49 AV |
1583 | return semctl_main(ns, semid, semnum, cmd, p); |
1584 | case SETVAL: | |
1585 | return semctl_setval(ns, semid, semnum, arg); | |
1da177e4 LT |
1586 | case IPC_RMID: |
1587 | case IPC_SET: | |
e1fd1f49 | 1588 | return semctl_down(ns, semid, cmd, version, p); |
1da177e4 LT |
1589 | default: |
1590 | return -EINVAL; | |
1591 | } | |
1592 | } | |
1593 | ||
1da177e4 LT |
1594 | /* If the task doesn't already have a undo_list, then allocate one |
1595 | * here. We guarantee there is only one thread using this undo list, | |
1596 | * and current is THE ONE | |
1597 | * | |
1598 | * If this allocation and assignment succeeds, but later | |
1599 | * portions of this code fail, there is no need to free the sem_undo_list. | |
1600 | * Just let it stay associated with the task, and it'll be freed later | |
1601 | * at exit time. | |
1602 | * | |
1603 | * This can block, so callers must hold no locks. | |
1604 | */ | |
1605 | static inline int get_undo_list(struct sem_undo_list **undo_listp) | |
1606 | { | |
1607 | struct sem_undo_list *undo_list; | |
1da177e4 LT |
1608 | |
1609 | undo_list = current->sysvsem.undo_list; | |
1610 | if (!undo_list) { | |
2453a306 | 1611 | undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL); |
1da177e4 LT |
1612 | if (undo_list == NULL) |
1613 | return -ENOMEM; | |
00a5dfdb | 1614 | spin_lock_init(&undo_list->lock); |
1da177e4 | 1615 | atomic_set(&undo_list->refcnt, 1); |
4daa28f6 MS |
1616 | INIT_LIST_HEAD(&undo_list->list_proc); |
1617 | ||
1da177e4 LT |
1618 | current->sysvsem.undo_list = undo_list; |
1619 | } | |
1620 | *undo_listp = undo_list; | |
1621 | return 0; | |
1622 | } | |
1623 | ||
bf17bb71 | 1624 | static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid) |
1da177e4 | 1625 | { |
bf17bb71 | 1626 | struct sem_undo *un; |
4daa28f6 | 1627 | |
bf17bb71 NP |
1628 | list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) { |
1629 | if (un->semid == semid) | |
1630 | return un; | |
1da177e4 | 1631 | } |
4daa28f6 | 1632 | return NULL; |
1da177e4 LT |
1633 | } |
1634 | ||
bf17bb71 NP |
1635 | static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) |
1636 | { | |
1637 | struct sem_undo *un; | |
1638 | ||
1639 | assert_spin_locked(&ulp->lock); | |
1640 | ||
1641 | un = __lookup_undo(ulp, semid); | |
1642 | if (un) { | |
1643 | list_del_rcu(&un->list_proc); | |
1644 | list_add_rcu(&un->list_proc, &ulp->list_proc); | |
1645 | } | |
1646 | return un; | |
1647 | } | |
1648 | ||
4daa28f6 MS |
1649 | /** |
1650 | * find_alloc_undo - Lookup (and if not present create) undo array | |
1651 | * @ns: namespace | |
1652 | * @semid: semaphore array id | |
1653 | * | |
1654 | * The function looks up (and if not present creates) the undo structure. | |
1655 | * The size of the undo structure depends on the size of the semaphore | |
1656 | * array, thus the alloc path is not that straightforward. | |
380af1b3 MS |
1657 | * Lifetime-rules: sem_undo is rcu-protected, on success, the function |
1658 | * performs a rcu_read_lock(). | |
4daa28f6 MS |
1659 | */ |
1660 | static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) | |
1da177e4 LT |
1661 | { |
1662 | struct sem_array *sma; | |
1663 | struct sem_undo_list *ulp; | |
1664 | struct sem_undo *un, *new; | |
6062a8dc | 1665 | int nsems, error; |
1da177e4 LT |
1666 | |
1667 | error = get_undo_list(&ulp); | |
1668 | if (error) | |
1669 | return ERR_PTR(error); | |
1670 | ||
380af1b3 | 1671 | rcu_read_lock(); |
c530c6ac | 1672 | spin_lock(&ulp->lock); |
1da177e4 | 1673 | un = lookup_undo(ulp, semid); |
c530c6ac | 1674 | spin_unlock(&ulp->lock); |
1da177e4 LT |
1675 | if (likely(un!=NULL)) |
1676 | goto out; | |
1677 | ||
1678 | /* no undo structure around - allocate one. */ | |
4daa28f6 | 1679 | /* step 1: figure out the size of the semaphore array */ |
16df3674 DB |
1680 | sma = sem_obtain_object_check(ns, semid); |
1681 | if (IS_ERR(sma)) { | |
1682 | rcu_read_unlock(); | |
4de85cd6 | 1683 | return ERR_CAST(sma); |
16df3674 | 1684 | } |
023a5355 | 1685 | |
1da177e4 | 1686 | nsems = sma->sem_nsems; |
6062a8dc RR |
1687 | if (!ipc_rcu_getref(sma)) { |
1688 | rcu_read_unlock(); | |
1689 | un = ERR_PTR(-EIDRM); | |
1690 | goto out; | |
1691 | } | |
16df3674 | 1692 | rcu_read_unlock(); |
1da177e4 | 1693 | |
4daa28f6 | 1694 | /* step 2: allocate new undo structure */ |
4668edc3 | 1695 | new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); |
1da177e4 | 1696 | if (!new) { |
53dad6d3 | 1697 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
1698 | return ERR_PTR(-ENOMEM); |
1699 | } | |
1da177e4 | 1700 | |
380af1b3 | 1701 | /* step 3: Acquire the lock on semaphore array */ |
4091fd94 | 1702 | rcu_read_lock(); |
6ff37972 | 1703 | sem_lock_and_putref(sma); |
0f3d2b01 | 1704 | if (!ipc_valid_object(&sma->sem_perm)) { |
6062a8dc | 1705 | sem_unlock(sma, -1); |
6d49dab8 | 1706 | rcu_read_unlock(); |
1da177e4 LT |
1707 | kfree(new); |
1708 | un = ERR_PTR(-EIDRM); | |
1709 | goto out; | |
1710 | } | |
380af1b3 MS |
1711 | spin_lock(&ulp->lock); |
1712 | ||
1713 | /* | |
1714 | * step 4: check for races: did someone else allocate the undo struct? | |
1715 | */ | |
1716 | un = lookup_undo(ulp, semid); | |
1717 | if (un) { | |
1718 | kfree(new); | |
1719 | goto success; | |
1720 | } | |
4daa28f6 MS |
1721 | /* step 5: initialize & link new undo structure */ |
1722 | new->semadj = (short *) &new[1]; | |
380af1b3 | 1723 | new->ulp = ulp; |
4daa28f6 MS |
1724 | new->semid = semid; |
1725 | assert_spin_locked(&ulp->lock); | |
380af1b3 | 1726 | list_add_rcu(&new->list_proc, &ulp->list_proc); |
cf9d5d78 | 1727 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1728 | list_add(&new->list_id, &sma->list_id); |
380af1b3 | 1729 | un = new; |
4daa28f6 | 1730 | |
380af1b3 | 1731 | success: |
c530c6ac | 1732 | spin_unlock(&ulp->lock); |
6062a8dc | 1733 | sem_unlock(sma, -1); |
1da177e4 LT |
1734 | out: |
1735 | return un; | |
1736 | } | |
1737 | ||
c61284e9 MS |
1738 | |
1739 | /** | |
1740 | * get_queue_result - Retrieve the result code from sem_queue | |
1741 | * @q: Pointer to queue structure | |
1742 | * | |
1743 | * Retrieve the return code from the pending queue. If IN_WAKEUP is found in | |
1744 | * q->status, then we must loop until the value is replaced with the final | |
1745 | * value: This may happen if a task is woken up by an unrelated event (e.g. | |
1746 | * signal) and in parallel the task is woken up by another task because it got | |
1747 | * the requested semaphores. | |
1748 | * | |
1749 | * The function can be called with or without holding the semaphore spinlock. | |
1750 | */ | |
1751 | static int get_queue_result(struct sem_queue *q) | |
1752 | { | |
1753 | int error; | |
1754 | ||
1755 | error = q->status; | |
1756 | while (unlikely(error == IN_WAKEUP)) { | |
1757 | cpu_relax(); | |
1758 | error = q->status; | |
1759 | } | |
1760 | ||
1761 | return error; | |
1762 | } | |
1763 | ||
d5460c99 HC |
1764 | SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, |
1765 | unsigned, nsops, const struct timespec __user *, timeout) | |
1da177e4 LT |
1766 | { |
1767 | int error = -EINVAL; | |
1768 | struct sem_array *sma; | |
1769 | struct sembuf fast_sops[SEMOPM_FAST]; | |
1770 | struct sembuf* sops = fast_sops, *sop; | |
1771 | struct sem_undo *un; | |
6062a8dc | 1772 | int undos = 0, alter = 0, max, locknum; |
1da177e4 LT |
1773 | struct sem_queue queue; |
1774 | unsigned long jiffies_left = 0; | |
e3893534 | 1775 | struct ipc_namespace *ns; |
0a2b9d4c | 1776 | struct list_head tasks; |
e3893534 KK |
1777 | |
1778 | ns = current->nsproxy->ipc_ns; | |
1da177e4 LT |
1779 | |
1780 | if (nsops < 1 || semid < 0) | |
1781 | return -EINVAL; | |
e3893534 | 1782 | if (nsops > ns->sc_semopm) |
1da177e4 LT |
1783 | return -E2BIG; |
1784 | if(nsops > SEMOPM_FAST) { | |
1785 | sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL); | |
1786 | if(sops==NULL) | |
1787 | return -ENOMEM; | |
1788 | } | |
1789 | if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) { | |
1790 | error=-EFAULT; | |
1791 | goto out_free; | |
1792 | } | |
1793 | if (timeout) { | |
1794 | struct timespec _timeout; | |
1795 | if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { | |
1796 | error = -EFAULT; | |
1797 | goto out_free; | |
1798 | } | |
1799 | if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || | |
1800 | _timeout.tv_nsec >= 1000000000L) { | |
1801 | error = -EINVAL; | |
1802 | goto out_free; | |
1803 | } | |
1804 | jiffies_left = timespec_to_jiffies(&_timeout); | |
1805 | } | |
1806 | max = 0; | |
1807 | for (sop = sops; sop < sops + nsops; sop++) { | |
1808 | if (sop->sem_num >= max) | |
1809 | max = sop->sem_num; | |
1810 | if (sop->sem_flg & SEM_UNDO) | |
b78755ab MS |
1811 | undos = 1; |
1812 | if (sop->sem_op != 0) | |
1da177e4 LT |
1813 | alter = 1; |
1814 | } | |
1da177e4 | 1815 | |
6062a8dc RR |
1816 | INIT_LIST_HEAD(&tasks); |
1817 | ||
1da177e4 | 1818 | if (undos) { |
6062a8dc | 1819 | /* On success, find_alloc_undo takes the rcu_read_lock */ |
4daa28f6 | 1820 | un = find_alloc_undo(ns, semid); |
1da177e4 LT |
1821 | if (IS_ERR(un)) { |
1822 | error = PTR_ERR(un); | |
1823 | goto out_free; | |
1824 | } | |
6062a8dc | 1825 | } else { |
1da177e4 | 1826 | un = NULL; |
6062a8dc RR |
1827 | rcu_read_lock(); |
1828 | } | |
1da177e4 | 1829 | |
16df3674 | 1830 | sma = sem_obtain_object_check(ns, semid); |
023a5355 | 1831 | if (IS_ERR(sma)) { |
6062a8dc | 1832 | rcu_read_unlock(); |
023a5355 | 1833 | error = PTR_ERR(sma); |
1da177e4 | 1834 | goto out_free; |
023a5355 ND |
1835 | } |
1836 | ||
16df3674 | 1837 | error = -EFBIG; |
c728b9c8 LT |
1838 | if (max >= sma->sem_nsems) |
1839 | goto out_rcu_wakeup; | |
16df3674 DB |
1840 | |
1841 | error = -EACCES; | |
c728b9c8 LT |
1842 | if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) |
1843 | goto out_rcu_wakeup; | |
16df3674 DB |
1844 | |
1845 | error = security_sem_semop(sma, sops, nsops, alter); | |
c728b9c8 LT |
1846 | if (error) |
1847 | goto out_rcu_wakeup; | |
16df3674 | 1848 | |
6e224f94 MS |
1849 | error = -EIDRM; |
1850 | locknum = sem_lock(sma, sops, nsops); | |
0f3d2b01 RA |
1851 | /* |
1852 | * We eventually might perform the following check in a lockless | |
1853 | * fashion, considering ipc_valid_object() locking constraints. | |
1854 | * If nsops == 1 and there is no contention for sem_perm.lock, then | |
1855 | * only a per-semaphore lock is held and it's OK to proceed with the | |
1856 | * check below. More details on the fine grained locking scheme | |
1857 | * entangled here and why it's RMID race safe on comments at sem_lock() | |
1858 | */ | |
1859 | if (!ipc_valid_object(&sma->sem_perm)) | |
6e224f94 | 1860 | goto out_unlock_free; |
1da177e4 | 1861 | /* |
4daa28f6 | 1862 | * semid identifiers are not unique - find_alloc_undo may have |
1da177e4 | 1863 | * allocated an undo structure, it was invalidated by an RMID |
4daa28f6 | 1864 | * and now a new array with received the same id. Check and fail. |
25985edc | 1865 | * This case can be detected checking un->semid. The existence of |
380af1b3 | 1866 | * "un" itself is guaranteed by rcu. |
1da177e4 | 1867 | */ |
6062a8dc RR |
1868 | if (un && un->semid == -1) |
1869 | goto out_unlock_free; | |
4daa28f6 | 1870 | |
758a6ba3 MS |
1871 | error = perform_atomic_semop(sma, sops, nsops, un, |
1872 | task_tgid_vnr(current)); | |
0e8c6656 MS |
1873 | if (error == 0) { |
1874 | /* If the operation was successful, then do | |
1875 | * the required updates. | |
1876 | */ | |
1877 | if (alter) | |
0a2b9d4c | 1878 | do_smart_update(sma, sops, nsops, 1, &tasks); |
0e8c6656 MS |
1879 | else |
1880 | set_semotime(sma, sops); | |
1da177e4 | 1881 | } |
0e8c6656 MS |
1882 | if (error <= 0) |
1883 | goto out_unlock_free; | |
1da177e4 LT |
1884 | |
1885 | /* We need to sleep on this operation, so we put the current | |
1886 | * task into the pending queue and go to sleep. | |
1887 | */ | |
1888 | ||
1da177e4 LT |
1889 | queue.sops = sops; |
1890 | queue.nsops = nsops; | |
1891 | queue.undo = un; | |
b488893a | 1892 | queue.pid = task_tgid_vnr(current); |
1da177e4 | 1893 | queue.alter = alter; |
1da177e4 | 1894 | |
b97e820f MS |
1895 | if (nsops == 1) { |
1896 | struct sem *curr; | |
1897 | curr = &sma->sem_base[sops->sem_num]; | |
1898 | ||
f269f40a MS |
1899 | if (alter) { |
1900 | if (sma->complex_count) { | |
1901 | list_add_tail(&queue.list, | |
1902 | &sma->pending_alter); | |
1903 | } else { | |
1904 | ||
1905 | list_add_tail(&queue.list, | |
1906 | &curr->pending_alter); | |
1907 | } | |
1908 | } else { | |
1a82e9e1 | 1909 | list_add_tail(&queue.list, &curr->pending_const); |
f269f40a | 1910 | } |
b97e820f | 1911 | } else { |
f269f40a MS |
1912 | if (!sma->complex_count) |
1913 | merge_queues(sma); | |
1914 | ||
9f1bc2c9 | 1915 | if (alter) |
1a82e9e1 | 1916 | list_add_tail(&queue.list, &sma->pending_alter); |
9f1bc2c9 | 1917 | else |
1a82e9e1 MS |
1918 | list_add_tail(&queue.list, &sma->pending_const); |
1919 | ||
b97e820f MS |
1920 | sma->complex_count++; |
1921 | } | |
1922 | ||
1da177e4 LT |
1923 | queue.status = -EINTR; |
1924 | queue.sleeper = current; | |
0b0577f6 MS |
1925 | |
1926 | sleep_again: | |
1da177e4 | 1927 | current->state = TASK_INTERRUPTIBLE; |
6062a8dc | 1928 | sem_unlock(sma, locknum); |
6d49dab8 | 1929 | rcu_read_unlock(); |
1da177e4 LT |
1930 | |
1931 | if (timeout) | |
1932 | jiffies_left = schedule_timeout(jiffies_left); | |
1933 | else | |
1934 | schedule(); | |
1935 | ||
c61284e9 | 1936 | error = get_queue_result(&queue); |
1da177e4 LT |
1937 | |
1938 | if (error != -EINTR) { | |
1939 | /* fast path: update_queue already obtained all requested | |
c61284e9 MS |
1940 | * resources. |
1941 | * Perform a smp_mb(): User space could assume that semop() | |
1942 | * is a memory barrier: Without the mb(), the cpu could | |
1943 | * speculatively read in user space stale data that was | |
1944 | * overwritten by the previous owner of the semaphore. | |
1945 | */ | |
1946 | smp_mb(); | |
1947 | ||
1da177e4 LT |
1948 | goto out_free; |
1949 | } | |
1950 | ||
321310ce | 1951 | rcu_read_lock(); |
6062a8dc | 1952 | sma = sem_obtain_lock(ns, semid, sops, nsops, &locknum); |
d694ad62 MS |
1953 | |
1954 | /* | |
1955 | * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing. | |
1956 | */ | |
1957 | error = get_queue_result(&queue); | |
1958 | ||
1959 | /* | |
1960 | * Array removed? If yes, leave without sem_unlock(). | |
1961 | */ | |
023a5355 | 1962 | if (IS_ERR(sma)) { |
321310ce | 1963 | rcu_read_unlock(); |
1da177e4 LT |
1964 | goto out_free; |
1965 | } | |
1966 | ||
c61284e9 | 1967 | |
1da177e4 | 1968 | /* |
d694ad62 MS |
1969 | * If queue.status != -EINTR we are woken up by another process. |
1970 | * Leave without unlink_queue(), but with sem_unlock(). | |
1da177e4 | 1971 | */ |
c61284e9 | 1972 | |
1da177e4 LT |
1973 | if (error != -EINTR) { |
1974 | goto out_unlock_free; | |
1975 | } | |
1976 | ||
1977 | /* | |
1978 | * If an interrupt occurred we have to clean up the queue | |
1979 | */ | |
1980 | if (timeout && jiffies_left == 0) | |
1981 | error = -EAGAIN; | |
0b0577f6 MS |
1982 | |
1983 | /* | |
1984 | * If the wakeup was spurious, just retry | |
1985 | */ | |
1986 | if (error == -EINTR && !signal_pending(current)) | |
1987 | goto sleep_again; | |
1988 | ||
b97e820f | 1989 | unlink_queue(sma, &queue); |
1da177e4 LT |
1990 | |
1991 | out_unlock_free: | |
6062a8dc | 1992 | sem_unlock(sma, locknum); |
c728b9c8 | 1993 | out_rcu_wakeup: |
6d49dab8 | 1994 | rcu_read_unlock(); |
0a2b9d4c | 1995 | wake_up_sem_queue_do(&tasks); |
1da177e4 LT |
1996 | out_free: |
1997 | if(sops != fast_sops) | |
1998 | kfree(sops); | |
1999 | return error; | |
2000 | } | |
2001 | ||
d5460c99 HC |
2002 | SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops, |
2003 | unsigned, nsops) | |
1da177e4 LT |
2004 | { |
2005 | return sys_semtimedop(semid, tsops, nsops, NULL); | |
2006 | } | |
2007 | ||
2008 | /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between | |
2009 | * parent and child tasks. | |
1da177e4 LT |
2010 | */ |
2011 | ||
2012 | int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) | |
2013 | { | |
2014 | struct sem_undo_list *undo_list; | |
2015 | int error; | |
2016 | ||
2017 | if (clone_flags & CLONE_SYSVSEM) { | |
2018 | error = get_undo_list(&undo_list); | |
2019 | if (error) | |
2020 | return error; | |
1da177e4 LT |
2021 | atomic_inc(&undo_list->refcnt); |
2022 | tsk->sysvsem.undo_list = undo_list; | |
2023 | } else | |
2024 | tsk->sysvsem.undo_list = NULL; | |
2025 | ||
2026 | return 0; | |
2027 | } | |
2028 | ||
2029 | /* | |
2030 | * add semadj values to semaphores, free undo structures. | |
2031 | * undo structures are not freed when semaphore arrays are destroyed | |
2032 | * so some of them may be out of date. | |
2033 | * IMPLEMENTATION NOTE: There is some confusion over whether the | |
2034 | * set of adjustments that needs to be done should be done in an atomic | |
2035 | * manner or not. That is, if we are attempting to decrement the semval | |
2036 | * should we queue up and wait until we can do so legally? | |
2037 | * The original implementation attempted to do this (queue and wait). | |
2038 | * The current implementation does not do so. The POSIX standard | |
2039 | * and SVID should be consulted to determine what behavior is mandated. | |
2040 | */ | |
2041 | void exit_sem(struct task_struct *tsk) | |
2042 | { | |
4daa28f6 | 2043 | struct sem_undo_list *ulp; |
1da177e4 | 2044 | |
4daa28f6 MS |
2045 | ulp = tsk->sysvsem.undo_list; |
2046 | if (!ulp) | |
1da177e4 | 2047 | return; |
9edff4ab | 2048 | tsk->sysvsem.undo_list = NULL; |
1da177e4 | 2049 | |
4daa28f6 | 2050 | if (!atomic_dec_and_test(&ulp->refcnt)) |
1da177e4 LT |
2051 | return; |
2052 | ||
380af1b3 | 2053 | for (;;) { |
1da177e4 | 2054 | struct sem_array *sma; |
380af1b3 | 2055 | struct sem_undo *un; |
0a2b9d4c | 2056 | struct list_head tasks; |
6062a8dc | 2057 | int semid, i; |
4daa28f6 | 2058 | |
380af1b3 | 2059 | rcu_read_lock(); |
05725f7e JP |
2060 | un = list_entry_rcu(ulp->list_proc.next, |
2061 | struct sem_undo, list_proc); | |
380af1b3 MS |
2062 | if (&un->list_proc == &ulp->list_proc) |
2063 | semid = -1; | |
2064 | else | |
2065 | semid = un->semid; | |
4daa28f6 | 2066 | |
6062a8dc RR |
2067 | if (semid == -1) { |
2068 | rcu_read_unlock(); | |
380af1b3 | 2069 | break; |
6062a8dc | 2070 | } |
1da177e4 | 2071 | |
6062a8dc | 2072 | sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, un->semid); |
380af1b3 | 2073 | /* exit_sem raced with IPC_RMID, nothing to do */ |
6062a8dc RR |
2074 | if (IS_ERR(sma)) { |
2075 | rcu_read_unlock(); | |
380af1b3 | 2076 | continue; |
6062a8dc | 2077 | } |
1da177e4 | 2078 | |
6062a8dc | 2079 | sem_lock(sma, NULL, -1); |
6e224f94 | 2080 | /* exit_sem raced with IPC_RMID, nothing to do */ |
0f3d2b01 | 2081 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
2082 | sem_unlock(sma, -1); |
2083 | rcu_read_unlock(); | |
2084 | continue; | |
2085 | } | |
bf17bb71 | 2086 | un = __lookup_undo(ulp, semid); |
380af1b3 MS |
2087 | if (un == NULL) { |
2088 | /* exit_sem raced with IPC_RMID+semget() that created | |
2089 | * exactly the same semid. Nothing to do. | |
2090 | */ | |
6062a8dc | 2091 | sem_unlock(sma, -1); |
6d49dab8 | 2092 | rcu_read_unlock(); |
380af1b3 MS |
2093 | continue; |
2094 | } | |
2095 | ||
2096 | /* remove un from the linked lists */ | |
cf9d5d78 | 2097 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 MS |
2098 | list_del(&un->list_id); |
2099 | ||
380af1b3 MS |
2100 | spin_lock(&ulp->lock); |
2101 | list_del_rcu(&un->list_proc); | |
2102 | spin_unlock(&ulp->lock); | |
2103 | ||
4daa28f6 MS |
2104 | /* perform adjustments registered in un */ |
2105 | for (i = 0; i < sma->sem_nsems; i++) { | |
5f921ae9 | 2106 | struct sem * semaphore = &sma->sem_base[i]; |
4daa28f6 MS |
2107 | if (un->semadj[i]) { |
2108 | semaphore->semval += un->semadj[i]; | |
1da177e4 LT |
2109 | /* |
2110 | * Range checks of the new semaphore value, | |
2111 | * not defined by sus: | |
2112 | * - Some unices ignore the undo entirely | |
2113 | * (e.g. HP UX 11i 11.22, Tru64 V5.1) | |
2114 | * - some cap the value (e.g. FreeBSD caps | |
2115 | * at 0, but doesn't enforce SEMVMX) | |
2116 | * | |
2117 | * Linux caps the semaphore value, both at 0 | |
2118 | * and at SEMVMX. | |
2119 | * | |
2120 | * Manfred <manfred@colorfullife.com> | |
2121 | */ | |
5f921ae9 IM |
2122 | if (semaphore->semval < 0) |
2123 | semaphore->semval = 0; | |
2124 | if (semaphore->semval > SEMVMX) | |
2125 | semaphore->semval = SEMVMX; | |
b488893a | 2126 | semaphore->sempid = task_tgid_vnr(current); |
1da177e4 LT |
2127 | } |
2128 | } | |
1da177e4 | 2129 | /* maybe some queued-up processes were waiting for this */ |
0a2b9d4c MS |
2130 | INIT_LIST_HEAD(&tasks); |
2131 | do_smart_update(sma, NULL, 0, 1, &tasks); | |
6062a8dc | 2132 | sem_unlock(sma, -1); |
6d49dab8 | 2133 | rcu_read_unlock(); |
0a2b9d4c | 2134 | wake_up_sem_queue_do(&tasks); |
380af1b3 | 2135 | |
693a8b6e | 2136 | kfree_rcu(un, rcu); |
1da177e4 | 2137 | } |
4daa28f6 | 2138 | kfree(ulp); |
1da177e4 LT |
2139 | } |
2140 | ||
2141 | #ifdef CONFIG_PROC_FS | |
19b4946c | 2142 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it) |
1da177e4 | 2143 | { |
1efdb69b | 2144 | struct user_namespace *user_ns = seq_user_ns(s); |
19b4946c | 2145 | struct sem_array *sma = it; |
d12e1e50 MS |
2146 | time_t sem_otime; |
2147 | ||
d8c63376 MS |
2148 | /* |
2149 | * The proc interface isn't aware of sem_lock(), it calls | |
2150 | * ipc_lock_object() directly (in sysvipc_find_ipc). | |
2151 | * In order to stay compatible with sem_lock(), we must wait until | |
2152 | * all simple semop() calls have left their critical regions. | |
2153 | */ | |
2154 | sem_wait_array(sma); | |
2155 | ||
d12e1e50 | 2156 | sem_otime = get_semotime(sma); |
19b4946c MW |
2157 | |
2158 | return seq_printf(s, | |
b97e820f | 2159 | "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n", |
19b4946c | 2160 | sma->sem_perm.key, |
7ca7e564 | 2161 | sma->sem_perm.id, |
19b4946c MW |
2162 | sma->sem_perm.mode, |
2163 | sma->sem_nsems, | |
1efdb69b EB |
2164 | from_kuid_munged(user_ns, sma->sem_perm.uid), |
2165 | from_kgid_munged(user_ns, sma->sem_perm.gid), | |
2166 | from_kuid_munged(user_ns, sma->sem_perm.cuid), | |
2167 | from_kgid_munged(user_ns, sma->sem_perm.cgid), | |
d12e1e50 | 2168 | sem_otime, |
19b4946c | 2169 | sma->sem_ctime); |
1da177e4 LT |
2170 | } |
2171 | #endif |