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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/ipc/sem.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 * Copyright (C) 1995 Eric Schenk, Bruno Haible
5 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
7 *
8 * SMP-threaded, sysctl's added
Christian Kujau624dffc2006-01-15 02:43:54 +01009 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * Enforced range limit on SEM_UNDO
Alan Cox046c6882009-01-05 14:06:29 +000011 * (c) 2001 Red Hat Inc
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 * Lockless wakeup
13 * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
Manfred Spraulc5cf6352010-05-26 14:43:43 -070014 * Further wakeup optimizations, documentation
15 * (c) 2010 Manfred Spraul <manfred@colorfullife.com>
Steve Grubb073115d2006-04-02 17:07:33 -040016 *
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
Kirill Korotaeve3893532006-10-02 02:18:22 -070019 *
20 * namespaces support
21 * OpenVZ, SWsoft Inc.
22 * Pavel Emelianov <xemul@openvz.org>
Manfred Spraulc5cf6352010-05-26 14:43:43 -070023 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 */
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070081#include <linux/security.h>
82#include <linux/syscalls.h>
83#include <linux/audit.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080084#include <linux/capability.h>
Mike Waychison19b49462005-09-06 15:17:10 -070085#include <linux/seq_file.h>
Nadia Derbey3e148c72007-10-18 23:40:54 -070086#include <linux/rwsem.h>
Kirill Korotaeve3893532006-10-02 02:18:22 -070087#include <linux/nsproxy.h>
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -080088#include <linux/ipc_namespace.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080089
Linus Torvalds1da177e2005-04-16 15:20:36 -070090#include <asm/uaccess.h>
91#include "util.h"
92
Pierre Peiffered2ddbf2008-02-08 04:18:57 -080093#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
Linus Torvalds1da177e2005-04-16 15:20:36 -070094
Kirill Korotaeve3893532006-10-02 02:18:22 -070095#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
Nadia Derbey1b531f22007-10-18 23:40:55 -070096#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
Nadia Derbey7748dbf2007-10-18 23:40:49 -070098static int newary(struct ipc_namespace *, struct ipc_params *);
Pierre Peiffer01b8b072008-02-08 04:18:57 -080099static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700101static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102#endif
103
104#define SEMMSL_FAST 256 /* 512 bytes on stack */
105#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
106
107/*
108 * linked list protection:
109 * sem_undo.id_next,
110 * sem_array.sem_pending{,last},
111 * sem_array.sem_undo: sem_lock() for read/write
112 * sem_undo.proc_next: only "current" is allowed to read/write that field.
113 *
114 */
115
Kirill Korotaeve3893532006-10-02 02:18:22 -0700116#define sc_semmsl sem_ctls[0]
117#define sc_semmns sem_ctls[1]
118#define sc_semopm sem_ctls[2]
119#define sc_semmni sem_ctls[3]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800121void sem_init_ns(struct ipc_namespace *ns)
Kirill Korotaeve3893532006-10-02 02:18:22 -0700122{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700123 ns->sc_semmsl = SEMMSL;
124 ns->sc_semmns = SEMMNS;
125 ns->sc_semopm = SEMOPM;
126 ns->sc_semmni = SEMMNI;
127 ns->used_sems = 0;
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800128 ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700129}
130
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800131#ifdef CONFIG_IPC_NS
Kirill Korotaeve3893532006-10-02 02:18:22 -0700132void sem_exit_ns(struct ipc_namespace *ns)
133{
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800134 free_ipcs(ns, &sem_ids(ns), freeary);
Serge E. Hallyn7d6feeb2009-12-15 16:47:27 -0800135 idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700136}
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800137#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
139void __init sem_init (void)
140{
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800141 sem_init_ns(&init_ipc_ns);
Mike Waychison19b49462005-09-06 15:17:10 -0700142 ipc_init_proc_interface("sysvipc/sem",
143 " key semid perms nsems uid gid cuid cgid otime ctime\n",
Kirill Korotaeve3893532006-10-02 02:18:22 -0700144 IPC_SEM_IDS, sysvipc_sem_proc_show);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145}
146
Nadia Derbey3e148c72007-10-18 23:40:54 -0700147/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700148 * sem_lock_(check_) routines are called in the paths where the rw_mutex
149 * is not held.
150 */
Nadia Derbey023a5352007-10-18 23:40:51 -0700151static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
152{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700153 struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
154
Pierre Peifferb1ed88b2008-02-06 01:36:23 -0800155 if (IS_ERR(ipcp))
156 return (struct sem_array *)ipcp;
157
Nadia Derbey03f02c72007-10-18 23:40:51 -0700158 return container_of(ipcp, struct sem_array, sem_perm);
Nadia Derbey023a5352007-10-18 23:40:51 -0700159}
160
161static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
162 int id)
163{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700164 struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id);
165
Pierre Peifferb1ed88b2008-02-06 01:36:23 -0800166 if (IS_ERR(ipcp))
167 return (struct sem_array *)ipcp;
168
Nadia Derbey03f02c72007-10-18 23:40:51 -0700169 return container_of(ipcp, struct sem_array, sem_perm);
Nadia Derbey023a5352007-10-18 23:40:51 -0700170}
171
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700172static inline void sem_lock_and_putref(struct sem_array *sma)
173{
174 ipc_lock_by_ptr(&sma->sem_perm);
175 ipc_rcu_putref(sma);
176}
177
178static inline void sem_getref_and_unlock(struct sem_array *sma)
179{
180 ipc_rcu_getref(sma);
181 ipc_unlock(&(sma)->sem_perm);
182}
183
184static inline void sem_putref(struct sem_array *sma)
185{
186 ipc_lock_by_ptr(&sma->sem_perm);
187 ipc_rcu_putref(sma);
188 ipc_unlock(&(sma)->sem_perm);
189}
190
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700191static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
192{
193 ipc_rmid(&sem_ids(ns), &s->sem_perm);
194}
195
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196/*
197 * Lockless wakeup algorithm:
198 * Without the check/retry algorithm a lockless wakeup is possible:
199 * - queue.status is initialized to -EINTR before blocking.
200 * - wakeup is performed by
201 * * unlinking the queue entry from sma->sem_pending
202 * * setting queue.status to IN_WAKEUP
203 * This is the notification for the blocked thread that a
204 * result value is imminent.
205 * * call wake_up_process
206 * * set queue.status to the final value.
207 * - the previously blocked thread checks queue.status:
208 * * if it's IN_WAKEUP, then it must wait until the value changes
209 * * if it's not -EINTR, then the operation was completed by
210 * update_queue. semtimedop can return queue.status without
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800211 * performing any operation on the sem array.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 * * otherwise it must acquire the spinlock and check what's up.
213 *
214 * The two-stage algorithm is necessary to protect against the following
215 * races:
216 * - if queue.status is set after wake_up_process, then the woken up idle
217 * thread could race forward and try (and fail) to acquire sma->lock
218 * before update_queue had a chance to set queue.status
219 * - if queue.status is written before wake_up_process and if the
220 * blocked process is woken up by a signal between writing
221 * queue.status and the wake_up_process, then the woken up
222 * process could return from semtimedop and die by calling
223 * sys_exit before wake_up_process is called. Then wake_up_process
224 * will oops, because the task structure is already invalid.
225 * (yes, this happened on s390 with sysv msg).
226 *
227 */
228#define IN_WAKEUP 1
229
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700230/**
231 * newary - Create a new semaphore set
232 * @ns: namespace
233 * @params: ptr to the structure that contains key, semflg and nsems
234 *
Nadia Derbey3e148c72007-10-18 23:40:54 -0700235 * Called with sem_ids.rw_mutex held (as a writer)
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700236 */
237
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700238static int newary(struct ipc_namespace *ns, struct ipc_params *params)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239{
240 int id;
241 int retval;
242 struct sem_array *sma;
243 int size;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700244 key_t key = params->key;
245 int nsems = params->u.nsems;
246 int semflg = params->flg;
Manfred Spraulb97e8202009-12-15 16:47:32 -0800247 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248
249 if (!nsems)
250 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700251 if (ns->used_sems + nsems > ns->sc_semmns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 return -ENOSPC;
253
254 size = sizeof (*sma) + nsems * sizeof (struct sem);
255 sma = ipc_rcu_alloc(size);
256 if (!sma) {
257 return -ENOMEM;
258 }
259 memset (sma, 0, size);
260
261 sma->sem_perm.mode = (semflg & S_IRWXUGO);
262 sma->sem_perm.key = key;
263
264 sma->sem_perm.security = NULL;
265 retval = security_sem_alloc(sma);
266 if (retval) {
267 ipc_rcu_putref(sma);
268 return retval;
269 }
270
Kirill Korotaeve3893532006-10-02 02:18:22 -0700271 id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
Pierre Peiffer283bb7f2007-10-18 23:40:57 -0700272 if (id < 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 security_sem_free(sma);
274 ipc_rcu_putref(sma);
Pierre Peiffer283bb7f2007-10-18 23:40:57 -0700275 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700277 ns->used_sems += nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278
279 sma->sem_base = (struct sem *) &sma[1];
Manfred Spraulb97e8202009-12-15 16:47:32 -0800280
281 for (i = 0; i < nsems; i++)
282 INIT_LIST_HEAD(&sma->sem_base[i].sem_pending);
283
284 sma->complex_count = 0;
Manfred Spraula1193f82008-07-25 01:48:06 -0700285 INIT_LIST_HEAD(&sma->sem_pending);
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700286 INIT_LIST_HEAD(&sma->list_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 sma->sem_nsems = nsems;
288 sma->sem_ctime = get_seconds();
289 sem_unlock(sma);
290
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700291 return sma->sem_perm.id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292}
293
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700294
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700295/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700296 * Called with sem_ids.rw_mutex and ipcp locked.
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700297 */
Nadia Derbey03f02c72007-10-18 23:40:51 -0700298static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700300 struct sem_array *sma;
301
302 sma = container_of(ipcp, struct sem_array, sem_perm);
303 return security_sem_associate(sma, semflg);
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700304}
305
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700306/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700307 * Called with sem_ids.rw_mutex and ipcp locked.
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700308 */
Nadia Derbey03f02c72007-10-18 23:40:51 -0700309static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
310 struct ipc_params *params)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700311{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700312 struct sem_array *sma;
313
314 sma = container_of(ipcp, struct sem_array, sem_perm);
315 if (params->u.nsems > sma->sem_nsems)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700316 return -EINVAL;
317
318 return 0;
319}
320
Heiko Carstensd5460c92009-01-14 14:14:27 +0100321SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700322{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700323 struct ipc_namespace *ns;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700324 struct ipc_ops sem_ops;
325 struct ipc_params sem_params;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
Kirill Korotaeve3893532006-10-02 02:18:22 -0700327 ns = current->nsproxy->ipc_ns;
328
329 if (nsems < 0 || nsems > ns->sc_semmsl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 return -EINVAL;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700331
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700332 sem_ops.getnew = newary;
333 sem_ops.associate = sem_security;
334 sem_ops.more_checks = sem_more_checks;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700335
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700336 sem_params.key = key;
337 sem_params.flg = semflg;
338 sem_params.u.nsems = nsems;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700339
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700340 return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341}
342
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343/*
344 * Determine whether a sequence of semaphore operations would succeed
345 * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
346 */
347
348static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
349 int nsops, struct sem_undo *un, int pid)
350{
351 int result, sem_op;
352 struct sembuf *sop;
353 struct sem * curr;
354
355 for (sop = sops; sop < sops + nsops; sop++) {
356 curr = sma->sem_base + sop->sem_num;
357 sem_op = sop->sem_op;
358 result = curr->semval;
359
360 if (!sem_op && result)
361 goto would_block;
362
363 result += sem_op;
364 if (result < 0)
365 goto would_block;
366 if (result > SEMVMX)
367 goto out_of_range;
368 if (sop->sem_flg & SEM_UNDO) {
369 int undo = un->semadj[sop->sem_num] - sem_op;
370 /*
371 * Exceeding the undo range is an error.
372 */
373 if (undo < (-SEMAEM - 1) || undo > SEMAEM)
374 goto out_of_range;
375 }
376 curr->semval = result;
377 }
378
379 sop--;
380 while (sop >= sops) {
381 sma->sem_base[sop->sem_num].sempid = pid;
382 if (sop->sem_flg & SEM_UNDO)
383 un->semadj[sop->sem_num] -= sop->sem_op;
384 sop--;
385 }
386
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 return 0;
388
389out_of_range:
390 result = -ERANGE;
391 goto undo;
392
393would_block:
394 if (sop->sem_flg & IPC_NOWAIT)
395 result = -EAGAIN;
396 else
397 result = 1;
398
399undo:
400 sop--;
401 while (sop >= sops) {
402 sma->sem_base[sop->sem_num].semval -= sop->sem_op;
403 sop--;
404 }
405
406 return result;
407}
408
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700409/** wake_up_sem_queue_prepare(q, error): Prepare wake-up
410 * @q: queue entry that must be signaled
411 * @error: Error value for the signal
412 *
413 * Prepare the wake-up of the queue entry q.
Nick Piggind4212092009-12-15 16:47:30 -0800414 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700415static void wake_up_sem_queue_prepare(struct list_head *pt,
416 struct sem_queue *q, int error)
Nick Piggind4212092009-12-15 16:47:30 -0800417{
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700418 if (list_empty(pt)) {
419 /*
420 * Hold preempt off so that we don't get preempted and have the
421 * wakee busy-wait until we're scheduled back on.
422 */
423 preempt_disable();
424 }
Nick Piggind4212092009-12-15 16:47:30 -0800425 q->status = IN_WAKEUP;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700426 q->pid = error;
427
428 list_add_tail(&q->simple_list, pt);
429}
430
431/**
432 * wake_up_sem_queue_do(pt) - do the actual wake-up
433 * @pt: list of tasks to be woken up
434 *
435 * Do the actual wake-up.
436 * The function is called without any locks held, thus the semaphore array
437 * could be destroyed already and the tasks can disappear as soon as the
438 * status is set to the actual return code.
439 */
440static void wake_up_sem_queue_do(struct list_head *pt)
441{
442 struct sem_queue *q, *t;
443 int did_something;
444
445 did_something = !list_empty(pt);
446 list_for_each_entry_safe(q, t, pt, simple_list) {
447 wake_up_process(q->sleeper);
448 /* q can disappear immediately after writing q->status. */
449 smp_wmb();
450 q->status = q->pid;
451 }
452 if (did_something)
453 preempt_enable();
Nick Piggind4212092009-12-15 16:47:30 -0800454}
455
Manfred Spraulb97e8202009-12-15 16:47:32 -0800456static void unlink_queue(struct sem_array *sma, struct sem_queue *q)
457{
458 list_del(&q->list);
459 if (q->nsops == 1)
460 list_del(&q->simple_list);
461 else
462 sma->complex_count--;
463}
464
Manfred Spraulfd5db422010-05-26 14:43:40 -0700465/** check_restart(sma, q)
466 * @sma: semaphore array
467 * @q: the operation that just completed
468 *
469 * update_queue is O(N^2) when it restarts scanning the whole queue of
470 * waiting operations. Therefore this function checks if the restart is
471 * really necessary. It is called after a previously waiting operation
472 * was completed.
473 */
474static int check_restart(struct sem_array *sma, struct sem_queue *q)
475{
476 struct sem *curr;
477 struct sem_queue *h;
478
479 /* if the operation didn't modify the array, then no restart */
480 if (q->alter == 0)
481 return 0;
482
483 /* pending complex operations are too difficult to analyse */
484 if (sma->complex_count)
485 return 1;
486
487 /* we were a sleeping complex operation. Too difficult */
488 if (q->nsops > 1)
489 return 1;
490
491 curr = sma->sem_base + q->sops[0].sem_num;
492
493 /* No-one waits on this queue */
494 if (list_empty(&curr->sem_pending))
495 return 0;
496
497 /* the new semaphore value */
498 if (curr->semval) {
499 /* It is impossible that someone waits for the new value:
500 * - q is a previously sleeping simple operation that
501 * altered the array. It must be a decrement, because
502 * simple increments never sleep.
503 * - The value is not 0, thus wait-for-zero won't proceed.
504 * - If there are older (higher priority) decrements
505 * in the queue, then they have observed the original
506 * semval value and couldn't proceed. The operation
507 * decremented to value - thus they won't proceed either.
508 */
509 BUG_ON(q->sops[0].sem_op >= 0);
510 return 0;
511 }
512 /*
513 * semval is 0. Check if there are wait-for-zero semops.
514 * They must be the first entries in the per-semaphore simple queue
515 */
516 h = list_first_entry(&curr->sem_pending, struct sem_queue, simple_list);
517 BUG_ON(h->nsops != 1);
518 BUG_ON(h->sops[0].sem_num != q->sops[0].sem_num);
519
520 /* Yes, there is a wait-for-zero semop. Restart */
521 if (h->sops[0].sem_op == 0)
522 return 1;
523
524 /* Again - no-one is waiting for the new value. */
525 return 0;
526}
527
Manfred Spraul636c6be2009-12-15 16:47:33 -0800528
529/**
530 * update_queue(sma, semnum): Look for tasks that can be completed.
531 * @sma: semaphore array.
532 * @semnum: semaphore that was modified.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700533 * @pt: list head for the tasks that must be woken up.
Manfred Spraul636c6be2009-12-15 16:47:33 -0800534 *
535 * update_queue must be called after a semaphore in a semaphore array
536 * was modified. If multiple semaphore were modified, then @semnum
537 * must be set to -1.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700538 * The tasks that must be woken up are added to @pt. The return code
539 * is stored in q->pid.
540 * The function return 1 if at least one semop was completed successfully.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700542static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543{
Manfred Spraul636c6be2009-12-15 16:47:33 -0800544 struct sem_queue *q;
545 struct list_head *walk;
546 struct list_head *pending_list;
547 int offset;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700548 int semop_completed = 0;
Manfred Spraul636c6be2009-12-15 16:47:33 -0800549
550 /* if there are complex operations around, then knowing the semaphore
551 * that was modified doesn't help us. Assume that multiple semaphores
552 * were modified.
553 */
554 if (sma->complex_count)
555 semnum = -1;
556
557 if (semnum == -1) {
558 pending_list = &sma->sem_pending;
559 offset = offsetof(struct sem_queue, list);
560 } else {
561 pending_list = &sma->sem_base[semnum].sem_pending;
562 offset = offsetof(struct sem_queue, simple_list);
563 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564
Nick Piggin9cad2002009-12-15 16:47:29 -0800565again:
Manfred Spraul636c6be2009-12-15 16:47:33 -0800566 walk = pending_list->next;
567 while (walk != pending_list) {
Manfred Spraulfd5db422010-05-26 14:43:40 -0700568 int error, restart;
Manfred Spraul636c6be2009-12-15 16:47:33 -0800569
570 q = (struct sem_queue *)((char *)walk - offset);
571 walk = walk->next;
Nick Piggin9cad2002009-12-15 16:47:29 -0800572
Manfred Sprauld987f8b2009-12-15 16:47:34 -0800573 /* If we are scanning the single sop, per-semaphore list of
574 * one semaphore and that semaphore is 0, then it is not
575 * necessary to scan the "alter" entries: simple increments
576 * that affect only one entry succeed immediately and cannot
577 * be in the per semaphore pending queue, and decrements
578 * cannot be successful if the value is already 0.
579 */
580 if (semnum != -1 && sma->sem_base[semnum].semval == 0 &&
581 q->alter)
582 break;
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 error = try_atomic_semop(sma, q->sops, q->nsops,
585 q->undo, q->pid);
586
587 /* Does q->sleeper still need to sleep? */
Nick Piggin9cad2002009-12-15 16:47:29 -0800588 if (error > 0)
589 continue;
Manfred Spraula1193f82008-07-25 01:48:06 -0700590
Manfred Spraulb97e8202009-12-15 16:47:32 -0800591 unlink_queue(sma, q);
Manfred Spraula1193f82008-07-25 01:48:06 -0700592
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700593 if (error) {
Manfred Spraulfd5db422010-05-26 14:43:40 -0700594 restart = 0;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700595 } else {
596 semop_completed = 1;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700597 restart = check_restart(sma, q);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700598 }
Manfred Spraulfd5db422010-05-26 14:43:40 -0700599
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700600 wake_up_sem_queue_prepare(pt, q, error);
Manfred Spraulfd5db422010-05-26 14:43:40 -0700601 if (restart)
Nick Piggin9cad2002009-12-15 16:47:29 -0800602 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 }
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700604 return semop_completed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605}
606
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700607/**
608 * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue
Manfred Spraulfd5db422010-05-26 14:43:40 -0700609 * @sma: semaphore array
610 * @sops: operations that were performed
611 * @nsops: number of operations
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700612 * @otime: force setting otime
613 * @pt: list head of the tasks that must be woken up.
Manfred Spraulfd5db422010-05-26 14:43:40 -0700614 *
615 * do_smart_update() does the required called to update_queue, based on the
616 * actual changes that were performed on the semaphore array.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700617 * Note that the function does not do the actual wake-up: the caller is
618 * responsible for calling wake_up_sem_queue_do(@pt).
619 * It is safe to perform this call after dropping all locks.
Manfred Spraulfd5db422010-05-26 14:43:40 -0700620 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700621static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops,
622 int otime, struct list_head *pt)
Manfred Spraulfd5db422010-05-26 14:43:40 -0700623{
624 int i;
625
626 if (sma->complex_count || sops == NULL) {
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700627 if (update_queue(sma, -1, pt))
628 otime = 1;
629 goto done;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700630 }
631
632 for (i = 0; i < nsops; i++) {
633 if (sops[i].sem_op > 0 ||
634 (sops[i].sem_op < 0 &&
635 sma->sem_base[sops[i].sem_num].semval == 0))
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700636 if (update_queue(sma, sops[i].sem_num, pt))
637 otime = 1;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700638 }
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700639done:
640 if (otime)
641 sma->sem_otime = get_seconds();
Manfred Spraulfd5db422010-05-26 14:43:40 -0700642}
643
644
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645/* The following counts are associated to each semaphore:
646 * semncnt number of tasks waiting on semval being nonzero
647 * semzcnt number of tasks waiting on semval being zero
648 * This model assumes that a task waits on exactly one semaphore.
649 * Since semaphore operations are to be performed atomically, tasks actually
650 * wait on a whole sequence of semaphores simultaneously.
651 * The counts we return here are a rough approximation, but still
652 * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
653 */
654static int count_semncnt (struct sem_array * sma, ushort semnum)
655{
656 int semncnt;
657 struct sem_queue * q;
658
659 semncnt = 0;
Manfred Spraula1193f82008-07-25 01:48:06 -0700660 list_for_each_entry(q, &sma->sem_pending, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 struct sembuf * sops = q->sops;
662 int nsops = q->nsops;
663 int i;
664 for (i = 0; i < nsops; i++)
665 if (sops[i].sem_num == semnum
666 && (sops[i].sem_op < 0)
667 && !(sops[i].sem_flg & IPC_NOWAIT))
668 semncnt++;
669 }
670 return semncnt;
671}
Manfred Spraula1193f82008-07-25 01:48:06 -0700672
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673static int count_semzcnt (struct sem_array * sma, ushort semnum)
674{
675 int semzcnt;
676 struct sem_queue * q;
677
678 semzcnt = 0;
Manfred Spraula1193f82008-07-25 01:48:06 -0700679 list_for_each_entry(q, &sma->sem_pending, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 struct sembuf * sops = q->sops;
681 int nsops = q->nsops;
682 int i;
683 for (i = 0; i < nsops; i++)
684 if (sops[i].sem_num == semnum
685 && (sops[i].sem_op == 0)
686 && !(sops[i].sem_flg & IPC_NOWAIT))
687 semzcnt++;
688 }
689 return semzcnt;
690}
691
Adrian Bunk6d97e232008-10-15 22:05:16 -0700692static void free_un(struct rcu_head *head)
Manfred Spraul380af1b2008-07-25 01:48:06 -0700693{
694 struct sem_undo *un = container_of(head, struct sem_undo, rcu);
695 kfree(un);
696}
697
Nadia Derbey3e148c72007-10-18 23:40:54 -0700698/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
699 * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
700 * remains locked on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701 */
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800702static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703{
Manfred Spraul380af1b2008-07-25 01:48:06 -0700704 struct sem_undo *un, *tu;
705 struct sem_queue *q, *tq;
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800706 struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700707 struct list_head tasks;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708
Manfred Spraul380af1b2008-07-25 01:48:06 -0700709 /* Free the existing undo structures for this semaphore set. */
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700710 assert_spin_locked(&sma->sem_perm.lock);
Manfred Spraul380af1b2008-07-25 01:48:06 -0700711 list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
712 list_del(&un->list_id);
713 spin_lock(&un->ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 un->semid = -1;
Manfred Spraul380af1b2008-07-25 01:48:06 -0700715 list_del_rcu(&un->list_proc);
716 spin_unlock(&un->ulp->lock);
717 call_rcu(&un->rcu, free_un);
718 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719
720 /* Wake up all pending processes and let them fail with EIDRM. */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700721 INIT_LIST_HEAD(&tasks);
Manfred Spraul380af1b2008-07-25 01:48:06 -0700722 list_for_each_entry_safe(q, tq, &sma->sem_pending, list) {
Manfred Spraulb97e8202009-12-15 16:47:32 -0800723 unlink_queue(sma, q);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700724 wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 }
726
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700727 /* Remove the semaphore set from the IDR */
728 sem_rmid(ns, sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 sem_unlock(sma);
730
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700731 wake_up_sem_queue_do(&tasks);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700732 ns->used_sems -= sma->sem_nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 security_sem_free(sma);
734 ipc_rcu_putref(sma);
735}
736
737static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
738{
739 switch(version) {
740 case IPC_64:
741 return copy_to_user(buf, in, sizeof(*in));
742 case IPC_OLD:
743 {
744 struct semid_ds out;
745
Dan Rosenberg982f7c22010-09-30 15:15:31 -0700746 memset(&out, 0, sizeof(out));
747
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
749
750 out.sem_otime = in->sem_otime;
751 out.sem_ctime = in->sem_ctime;
752 out.sem_nsems = in->sem_nsems;
753
754 return copy_to_user(buf, &out, sizeof(out));
755 }
756 default:
757 return -EINVAL;
758 }
759}
760
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800761static int semctl_nolock(struct ipc_namespace *ns, int semid,
762 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763{
Amerigo Wange5cc9c72009-12-15 16:47:35 -0800764 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 struct sem_array *sma;
766
767 switch(cmd) {
768 case IPC_INFO:
769 case SEM_INFO:
770 {
771 struct seminfo seminfo;
772 int max_id;
773
774 err = security_sem_semctl(NULL, cmd);
775 if (err)
776 return err;
777
778 memset(&seminfo,0,sizeof(seminfo));
Kirill Korotaeve3893532006-10-02 02:18:22 -0700779 seminfo.semmni = ns->sc_semmni;
780 seminfo.semmns = ns->sc_semmns;
781 seminfo.semmsl = ns->sc_semmsl;
782 seminfo.semopm = ns->sc_semopm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 seminfo.semvmx = SEMVMX;
784 seminfo.semmnu = SEMMNU;
785 seminfo.semmap = SEMMAP;
786 seminfo.semume = SEMUME;
Nadia Derbey3e148c72007-10-18 23:40:54 -0700787 down_read(&sem_ids(ns).rw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 if (cmd == SEM_INFO) {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700789 seminfo.semusz = sem_ids(ns).in_use;
790 seminfo.semaem = ns->used_sems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 } else {
792 seminfo.semusz = SEMUSZ;
793 seminfo.semaem = SEMAEM;
794 }
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700795 max_id = ipc_get_maxid(&sem_ids(ns));
Nadia Derbey3e148c72007-10-18 23:40:54 -0700796 up_read(&sem_ids(ns).rw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
798 return -EFAULT;
799 return (max_id < 0) ? 0: max_id;
800 }
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800801 case IPC_STAT:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 case SEM_STAT:
803 {
804 struct semid64_ds tbuf;
805 int id;
806
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800807 if (cmd == SEM_STAT) {
808 sma = sem_lock(ns, semid);
809 if (IS_ERR(sma))
810 return PTR_ERR(sma);
811 id = sma->sem_perm.id;
812 } else {
813 sma = sem_lock_check(ns, semid);
814 if (IS_ERR(sma))
815 return PTR_ERR(sma);
816 id = 0;
817 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818
819 err = -EACCES;
Serge E. Hallynb0e77592011-03-23 16:43:24 -0700820 if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 goto out_unlock;
822
823 err = security_sem_semctl(sma, cmd);
824 if (err)
825 goto out_unlock;
826
Nadia Derbey023a5352007-10-18 23:40:51 -0700827 memset(&tbuf, 0, sizeof(tbuf));
828
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
830 tbuf.sem_otime = sma->sem_otime;
831 tbuf.sem_ctime = sma->sem_ctime;
832 tbuf.sem_nsems = sma->sem_nsems;
833 sem_unlock(sma);
834 if (copy_semid_to_user (arg.buf, &tbuf, version))
835 return -EFAULT;
836 return id;
837 }
838 default:
839 return -EINVAL;
840 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841out_unlock:
842 sem_unlock(sma);
843 return err;
844}
845
Kirill Korotaeve3893532006-10-02 02:18:22 -0700846static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
847 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848{
849 struct sem_array *sma;
850 struct sem* curr;
851 int err;
852 ushort fast_sem_io[SEMMSL_FAST];
853 ushort* sem_io = fast_sem_io;
854 int nsems;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700855 struct list_head tasks;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856
Nadia Derbey023a5352007-10-18 23:40:51 -0700857 sma = sem_lock_check(ns, semid);
858 if (IS_ERR(sma))
859 return PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700861 INIT_LIST_HEAD(&tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 nsems = sma->sem_nsems;
863
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 err = -EACCES;
Serge E. Hallynb0e77592011-03-23 16:43:24 -0700865 if (ipcperms(ns, &sma->sem_perm,
866 (cmd == SETVAL || cmd == SETALL) ? S_IWUGO : S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 goto out_unlock;
868
869 err = security_sem_semctl(sma, cmd);
870 if (err)
871 goto out_unlock;
872
873 err = -EACCES;
874 switch (cmd) {
875 case GETALL:
876 {
877 ushort __user *array = arg.array;
878 int i;
879
880 if(nsems > SEMMSL_FAST) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700881 sem_getref_and_unlock(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
883 sem_io = ipc_alloc(sizeof(ushort)*nsems);
884 if(sem_io == NULL) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700885 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 return -ENOMEM;
887 }
888
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700889 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 if (sma->sem_perm.deleted) {
891 sem_unlock(sma);
892 err = -EIDRM;
893 goto out_free;
894 }
895 }
896
897 for (i = 0; i < sma->sem_nsems; i++)
898 sem_io[i] = sma->sem_base[i].semval;
899 sem_unlock(sma);
900 err = 0;
901 if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
902 err = -EFAULT;
903 goto out_free;
904 }
905 case SETALL:
906 {
907 int i;
908 struct sem_undo *un;
909
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700910 sem_getref_and_unlock(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911
912 if(nsems > SEMMSL_FAST) {
913 sem_io = ipc_alloc(sizeof(ushort)*nsems);
914 if(sem_io == NULL) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700915 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 return -ENOMEM;
917 }
918 }
919
920 if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700921 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 err = -EFAULT;
923 goto out_free;
924 }
925
926 for (i = 0; i < nsems; i++) {
927 if (sem_io[i] > SEMVMX) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700928 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 err = -ERANGE;
930 goto out_free;
931 }
932 }
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700933 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 if (sma->sem_perm.deleted) {
935 sem_unlock(sma);
936 err = -EIDRM;
937 goto out_free;
938 }
939
940 for (i = 0; i < nsems; i++)
941 sma->sem_base[i].semval = sem_io[i];
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700942
943 assert_spin_locked(&sma->sem_perm.lock);
944 list_for_each_entry(un, &sma->list_id, list_id) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 for (i = 0; i < nsems; i++)
946 un->semadj[i] = 0;
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700947 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 sma->sem_ctime = get_seconds();
949 /* maybe some queued-up processes were waiting for this */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700950 do_smart_update(sma, NULL, 0, 0, &tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 err = 0;
952 goto out_unlock;
953 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 /* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
955 }
956 err = -EINVAL;
957 if(semnum < 0 || semnum >= nsems)
958 goto out_unlock;
959
960 curr = &sma->sem_base[semnum];
961
962 switch (cmd) {
963 case GETVAL:
964 err = curr->semval;
965 goto out_unlock;
966 case GETPID:
967 err = curr->sempid;
968 goto out_unlock;
969 case GETNCNT:
970 err = count_semncnt(sma,semnum);
971 goto out_unlock;
972 case GETZCNT:
973 err = count_semzcnt(sma,semnum);
974 goto out_unlock;
975 case SETVAL:
976 {
977 int val = arg.val;
978 struct sem_undo *un;
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 err = -ERANGE;
981 if (val > SEMVMX || val < 0)
982 goto out_unlock;
983
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700984 assert_spin_locked(&sma->sem_perm.lock);
985 list_for_each_entry(un, &sma->list_id, list_id)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 un->semadj[semnum] = 0;
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700987
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 curr->semval = val;
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700989 curr->sempid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 sma->sem_ctime = get_seconds();
991 /* maybe some queued-up processes were waiting for this */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700992 do_smart_update(sma, NULL, 0, 0, &tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 err = 0;
994 goto out_unlock;
995 }
996 }
997out_unlock:
998 sem_unlock(sma);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700999 wake_up_sem_queue_do(&tasks);
1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001out_free:
1002 if(sem_io != fast_sem_io)
1003 ipc_free(sem_io, sizeof(ushort)*nsems);
1004 return err;
1005}
1006
Pierre Peiffer016d7132008-04-29 01:00:50 -07001007static inline unsigned long
1008copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009{
1010 switch(version) {
1011 case IPC_64:
Pierre Peiffer016d7132008-04-29 01:00:50 -07001012 if (copy_from_user(out, buf, sizeof(*out)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 case IPC_OLD:
1016 {
1017 struct semid_ds tbuf_old;
1018
1019 if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
1020 return -EFAULT;
1021
Pierre Peiffer016d7132008-04-29 01:00:50 -07001022 out->sem_perm.uid = tbuf_old.sem_perm.uid;
1023 out->sem_perm.gid = tbuf_old.sem_perm.gid;
1024 out->sem_perm.mode = tbuf_old.sem_perm.mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025
1026 return 0;
1027 }
1028 default:
1029 return -EINVAL;
1030 }
1031}
1032
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001033/*
1034 * This function handles some semctl commands which require the rw_mutex
1035 * to be held in write mode.
1036 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
1037 */
Pierre Peiffer21a48262008-04-29 01:00:49 -07001038static int semctl_down(struct ipc_namespace *ns, int semid,
1039 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040{
1041 struct sem_array *sma;
1042 int err;
Pierre Peiffer016d7132008-04-29 01:00:50 -07001043 struct semid64_ds semid64;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 struct kern_ipc_perm *ipcp;
1045
1046 if(cmd == IPC_SET) {
Pierre Peiffer016d7132008-04-29 01:00:50 -07001047 if (copy_semid_from_user(&semid64, arg.buf, version))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
Serge E. Hallynb0e77592011-03-23 16:43:24 -07001051 ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd,
1052 &semid64.sem_perm, 0);
Pierre Peiffera5f75e72008-04-29 01:00:54 -07001053 if (IS_ERR(ipcp))
1054 return PTR_ERR(ipcp);
Steve Grubb073115d2006-04-02 17:07:33 -04001055
Pierre Peiffera5f75e72008-04-29 01:00:54 -07001056 sma = container_of(ipcp, struct sem_array, sem_perm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057
1058 err = security_sem_semctl(sma, cmd);
1059 if (err)
1060 goto out_unlock;
1061
1062 switch(cmd){
1063 case IPC_RMID:
Pierre Peiffer01b8b072008-02-08 04:18:57 -08001064 freeary(ns, ipcp);
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001065 goto out_up;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 case IPC_SET:
Pierre Peiffer8f4a3802008-04-29 01:00:51 -07001067 ipc_update_perm(&semid64.sem_perm, ipcp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 sma->sem_ctime = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 break;
1070 default:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 err = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073
1074out_unlock:
1075 sem_unlock(sma);
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001076out_up:
1077 up_write(&sem_ids(ns).rw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 return err;
1079}
1080
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001081SYSCALL_DEFINE(semctl)(int semid, int semnum, int cmd, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082{
1083 int err = -EINVAL;
1084 int version;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001085 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086
1087 if (semid < 0)
1088 return -EINVAL;
1089
1090 version = ipc_parse_version(&cmd);
Kirill Korotaeve3893532006-10-02 02:18:22 -07001091 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092
1093 switch(cmd) {
1094 case IPC_INFO:
1095 case SEM_INFO:
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -08001096 case IPC_STAT:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 case SEM_STAT:
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -08001098 err = semctl_nolock(ns, semid, cmd, version, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 return err;
1100 case GETALL:
1101 case GETVAL:
1102 case GETPID:
1103 case GETNCNT:
1104 case GETZCNT:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 case SETVAL:
1106 case SETALL:
Kirill Korotaeve3893532006-10-02 02:18:22 -07001107 err = semctl_main(ns,semid,semnum,cmd,version,arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 return err;
1109 case IPC_RMID:
1110 case IPC_SET:
Pierre Peiffer21a48262008-04-29 01:00:49 -07001111 err = semctl_down(ns, semid, cmd, version, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 return err;
1113 default:
1114 return -EINVAL;
1115 }
1116}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001117#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1118asmlinkage long SyS_semctl(int semid, int semnum, int cmd, union semun arg)
1119{
1120 return SYSC_semctl((int) semid, (int) semnum, (int) cmd, arg);
1121}
1122SYSCALL_ALIAS(sys_semctl, SyS_semctl);
1123#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125/* If the task doesn't already have a undo_list, then allocate one
1126 * here. We guarantee there is only one thread using this undo list,
1127 * and current is THE ONE
1128 *
1129 * If this allocation and assignment succeeds, but later
1130 * portions of this code fail, there is no need to free the sem_undo_list.
1131 * Just let it stay associated with the task, and it'll be freed later
1132 * at exit time.
1133 *
1134 * This can block, so callers must hold no locks.
1135 */
1136static inline int get_undo_list(struct sem_undo_list **undo_listp)
1137{
1138 struct sem_undo_list *undo_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139
1140 undo_list = current->sysvsem.undo_list;
1141 if (!undo_list) {
Matt Helsley2453a302006-10-02 02:18:25 -07001142 undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 if (undo_list == NULL)
1144 return -ENOMEM;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +02001145 spin_lock_init(&undo_list->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 atomic_set(&undo_list->refcnt, 1);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001147 INIT_LIST_HEAD(&undo_list->list_proc);
1148
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 current->sysvsem.undo_list = undo_list;
1150 }
1151 *undo_listp = undo_list;
1152 return 0;
1153}
1154
Nick Pigginbf17bb72009-12-15 16:47:28 -08001155static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156{
Nick Pigginbf17bb72009-12-15 16:47:28 -08001157 struct sem_undo *un;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158
Nick Pigginbf17bb72009-12-15 16:47:28 -08001159 list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
1160 if (un->semid == semid)
1161 return un;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001163 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164}
1165
Nick Pigginbf17bb72009-12-15 16:47:28 -08001166static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1167{
1168 struct sem_undo *un;
1169
1170 assert_spin_locked(&ulp->lock);
1171
1172 un = __lookup_undo(ulp, semid);
1173 if (un) {
1174 list_del_rcu(&un->list_proc);
1175 list_add_rcu(&un->list_proc, &ulp->list_proc);
1176 }
1177 return un;
1178}
1179
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001180/**
1181 * find_alloc_undo - Lookup (and if not present create) undo array
1182 * @ns: namespace
1183 * @semid: semaphore array id
1184 *
1185 * The function looks up (and if not present creates) the undo structure.
1186 * The size of the undo structure depends on the size of the semaphore
1187 * array, thus the alloc path is not that straightforward.
Manfred Spraul380af1b2008-07-25 01:48:06 -07001188 * Lifetime-rules: sem_undo is rcu-protected, on success, the function
1189 * performs a rcu_read_lock().
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001190 */
1191static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192{
1193 struct sem_array *sma;
1194 struct sem_undo_list *ulp;
1195 struct sem_undo *un, *new;
1196 int nsems;
1197 int error;
1198
1199 error = get_undo_list(&ulp);
1200 if (error)
1201 return ERR_PTR(error);
1202
Manfred Spraul380af1b2008-07-25 01:48:06 -07001203 rcu_read_lock();
Pierre Peifferc530c6a2007-10-18 23:40:55 -07001204 spin_lock(&ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 un = lookup_undo(ulp, semid);
Pierre Peifferc530c6a2007-10-18 23:40:55 -07001206 spin_unlock(&ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 if (likely(un!=NULL))
1208 goto out;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001209 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210
1211 /* no undo structure around - allocate one. */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001212 /* step 1: figure out the size of the semaphore array */
Nadia Derbey023a5352007-10-18 23:40:51 -07001213 sma = sem_lock_check(ns, semid);
1214 if (IS_ERR(sma))
Julia Lawall4de85cd2010-05-26 14:43:44 -07001215 return ERR_CAST(sma);
Nadia Derbey023a5352007-10-18 23:40:51 -07001216
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 nsems = sma->sem_nsems;
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001218 sem_getref_and_unlock(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001220 /* step 2: allocate new undo structure */
Burman Yan4668edc2006-12-06 20:38:51 -08001221 new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 if (!new) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001223 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 return ERR_PTR(-ENOMEM);
1225 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226
Manfred Spraul380af1b2008-07-25 01:48:06 -07001227 /* step 3: Acquire the lock on semaphore array */
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001228 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 if (sma->sem_perm.deleted) {
1230 sem_unlock(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 kfree(new);
1232 un = ERR_PTR(-EIDRM);
1233 goto out;
1234 }
Manfred Spraul380af1b2008-07-25 01:48:06 -07001235 spin_lock(&ulp->lock);
1236
1237 /*
1238 * step 4: check for races: did someone else allocate the undo struct?
1239 */
1240 un = lookup_undo(ulp, semid);
1241 if (un) {
1242 kfree(new);
1243 goto success;
1244 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001245 /* step 5: initialize & link new undo structure */
1246 new->semadj = (short *) &new[1];
Manfred Spraul380af1b2008-07-25 01:48:06 -07001247 new->ulp = ulp;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001248 new->semid = semid;
1249 assert_spin_locked(&ulp->lock);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001250 list_add_rcu(&new->list_proc, &ulp->list_proc);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001251 assert_spin_locked(&sma->sem_perm.lock);
1252 list_add(&new->list_id, &sma->list_id);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001253 un = new;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001254
1255success:
1256 spin_unlock(&ulp->lock);
1257 rcu_read_lock();
1258 sem_unlock(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259out:
1260 return un;
1261}
1262
Manfred Spraulc61284e2010-07-20 13:24:23 -07001263
1264/**
1265 * get_queue_result - Retrieve the result code from sem_queue
1266 * @q: Pointer to queue structure
1267 *
1268 * Retrieve the return code from the pending queue. If IN_WAKEUP is found in
1269 * q->status, then we must loop until the value is replaced with the final
1270 * value: This may happen if a task is woken up by an unrelated event (e.g.
1271 * signal) and in parallel the task is woken up by another task because it got
1272 * the requested semaphores.
1273 *
1274 * The function can be called with or without holding the semaphore spinlock.
1275 */
1276static int get_queue_result(struct sem_queue *q)
1277{
1278 int error;
1279
1280 error = q->status;
1281 while (unlikely(error == IN_WAKEUP)) {
1282 cpu_relax();
1283 error = q->status;
1284 }
1285
1286 return error;
1287}
1288
1289
Heiko Carstensd5460c92009-01-14 14:14:27 +01001290SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
1291 unsigned, nsops, const struct timespec __user *, timeout)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292{
1293 int error = -EINVAL;
1294 struct sem_array *sma;
1295 struct sembuf fast_sops[SEMOPM_FAST];
1296 struct sembuf* sops = fast_sops, *sop;
1297 struct sem_undo *un;
Manfred Spraulb78755a2005-06-23 00:10:06 -07001298 int undos = 0, alter = 0, max;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 struct sem_queue queue;
1300 unsigned long jiffies_left = 0;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001301 struct ipc_namespace *ns;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001302 struct list_head tasks;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001303
1304 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
1306 if (nsops < 1 || semid < 0)
1307 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001308 if (nsops > ns->sc_semopm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 return -E2BIG;
1310 if(nsops > SEMOPM_FAST) {
1311 sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
1312 if(sops==NULL)
1313 return -ENOMEM;
1314 }
1315 if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1316 error=-EFAULT;
1317 goto out_free;
1318 }
1319 if (timeout) {
1320 struct timespec _timeout;
1321 if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1322 error = -EFAULT;
1323 goto out_free;
1324 }
1325 if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1326 _timeout.tv_nsec >= 1000000000L) {
1327 error = -EINVAL;
1328 goto out_free;
1329 }
1330 jiffies_left = timespec_to_jiffies(&_timeout);
1331 }
1332 max = 0;
1333 for (sop = sops; sop < sops + nsops; sop++) {
1334 if (sop->sem_num >= max)
1335 max = sop->sem_num;
1336 if (sop->sem_flg & SEM_UNDO)
Manfred Spraulb78755a2005-06-23 00:10:06 -07001337 undos = 1;
1338 if (sop->sem_op != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 alter = 1;
1340 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 if (undos) {
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001343 un = find_alloc_undo(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344 if (IS_ERR(un)) {
1345 error = PTR_ERR(un);
1346 goto out_free;
1347 }
1348 } else
1349 un = NULL;
1350
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001351 INIT_LIST_HEAD(&tasks);
1352
Nadia Derbey023a5352007-10-18 23:40:51 -07001353 sma = sem_lock_check(ns, semid);
1354 if (IS_ERR(sma)) {
Manfred Spraul380af1b2008-07-25 01:48:06 -07001355 if (un)
1356 rcu_read_unlock();
Nadia Derbey023a5352007-10-18 23:40:51 -07001357 error = PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 goto out_free;
Nadia Derbey023a5352007-10-18 23:40:51 -07001359 }
1360
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 /*
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001362 * semid identifiers are not unique - find_alloc_undo may have
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 * allocated an undo structure, it was invalidated by an RMID
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001364 * and now a new array with received the same id. Check and fail.
Manfred Spraul380af1b2008-07-25 01:48:06 -07001365 * This case can be detected checking un->semid. The existance of
1366 * "un" itself is guaranteed by rcu.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001368 error = -EIDRM;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001369 if (un) {
1370 if (un->semid == -1) {
1371 rcu_read_unlock();
1372 goto out_unlock_free;
1373 } else {
1374 /*
1375 * rcu lock can be released, "un" cannot disappear:
1376 * - sem_lock is acquired, thus IPC_RMID is
1377 * impossible.
1378 * - exit_sem is impossible, it always operates on
1379 * current (or a dead task).
1380 */
1381
1382 rcu_read_unlock();
1383 }
1384 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001385
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 error = -EFBIG;
1387 if (max >= sma->sem_nsems)
1388 goto out_unlock_free;
1389
1390 error = -EACCES;
Serge E. Hallynb0e77592011-03-23 16:43:24 -07001391 if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 goto out_unlock_free;
1393
1394 error = security_sem_semop(sma, sops, nsops, alter);
1395 if (error)
1396 goto out_unlock_free;
1397
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001398 error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 if (error <= 0) {
1400 if (alter && error == 0)
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001401 do_smart_update(sma, sops, nsops, 1, &tasks);
Manfred Spraul636c6be2009-12-15 16:47:33 -08001402
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 goto out_unlock_free;
1404 }
1405
1406 /* We need to sleep on this operation, so we put the current
1407 * task into the pending queue and go to sleep.
1408 */
1409
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 queue.sops = sops;
1411 queue.nsops = nsops;
1412 queue.undo = un;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001413 queue.pid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 queue.alter = alter;
1415 if (alter)
Manfred Spraula1193f82008-07-25 01:48:06 -07001416 list_add_tail(&queue.list, &sma->sem_pending);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 else
Manfred Spraula1193f82008-07-25 01:48:06 -07001418 list_add(&queue.list, &sma->sem_pending);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419
Manfred Spraulb97e8202009-12-15 16:47:32 -08001420 if (nsops == 1) {
1421 struct sem *curr;
1422 curr = &sma->sem_base[sops->sem_num];
1423
1424 if (alter)
1425 list_add_tail(&queue.simple_list, &curr->sem_pending);
1426 else
1427 list_add(&queue.simple_list, &curr->sem_pending);
1428 } else {
1429 INIT_LIST_HEAD(&queue.simple_list);
1430 sma->complex_count++;
1431 }
1432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 queue.status = -EINTR;
1434 queue.sleeper = current;
1435 current->state = TASK_INTERRUPTIBLE;
1436 sem_unlock(sma);
1437
1438 if (timeout)
1439 jiffies_left = schedule_timeout(jiffies_left);
1440 else
1441 schedule();
1442
Manfred Spraulc61284e2010-07-20 13:24:23 -07001443 error = get_queue_result(&queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444
1445 if (error != -EINTR) {
1446 /* fast path: update_queue already obtained all requested
Manfred Spraulc61284e2010-07-20 13:24:23 -07001447 * resources.
1448 * Perform a smp_mb(): User space could assume that semop()
1449 * is a memory barrier: Without the mb(), the cpu could
1450 * speculatively read in user space stale data that was
1451 * overwritten by the previous owner of the semaphore.
1452 */
1453 smp_mb();
1454
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 goto out_free;
1456 }
1457
Kirill Korotaeve3893532006-10-02 02:18:22 -07001458 sma = sem_lock(ns, semid);
Nadia Derbey023a5352007-10-18 23:40:51 -07001459 if (IS_ERR(sma)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 error = -EIDRM;
1461 goto out_free;
1462 }
1463
Manfred Spraulc61284e2010-07-20 13:24:23 -07001464 error = get_queue_result(&queue);
1465
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 /*
1467 * If queue.status != -EINTR we are woken up by another process
1468 */
Manfred Spraulc61284e2010-07-20 13:24:23 -07001469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 if (error != -EINTR) {
1471 goto out_unlock_free;
1472 }
1473
1474 /*
1475 * If an interrupt occurred we have to clean up the queue
1476 */
1477 if (timeout && jiffies_left == 0)
1478 error = -EAGAIN;
Manfred Spraulb97e8202009-12-15 16:47:32 -08001479 unlink_queue(sma, &queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480
1481out_unlock_free:
1482 sem_unlock(sma);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001483
1484 wake_up_sem_queue_do(&tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485out_free:
1486 if(sops != fast_sops)
1487 kfree(sops);
1488 return error;
1489}
1490
Heiko Carstensd5460c92009-01-14 14:14:27 +01001491SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
1492 unsigned, nsops)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493{
1494 return sys_semtimedop(semid, tsops, nsops, NULL);
1495}
1496
1497/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1498 * parent and child tasks.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 */
1500
1501int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1502{
1503 struct sem_undo_list *undo_list;
1504 int error;
1505
1506 if (clone_flags & CLONE_SYSVSEM) {
1507 error = get_undo_list(&undo_list);
1508 if (error)
1509 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 atomic_inc(&undo_list->refcnt);
1511 tsk->sysvsem.undo_list = undo_list;
1512 } else
1513 tsk->sysvsem.undo_list = NULL;
1514
1515 return 0;
1516}
1517
1518/*
1519 * add semadj values to semaphores, free undo structures.
1520 * undo structures are not freed when semaphore arrays are destroyed
1521 * so some of them may be out of date.
1522 * IMPLEMENTATION NOTE: There is some confusion over whether the
1523 * set of adjustments that needs to be done should be done in an atomic
1524 * manner or not. That is, if we are attempting to decrement the semval
1525 * should we queue up and wait until we can do so legally?
1526 * The original implementation attempted to do this (queue and wait).
1527 * The current implementation does not do so. The POSIX standard
1528 * and SVID should be consulted to determine what behavior is mandated.
1529 */
1530void exit_sem(struct task_struct *tsk)
1531{
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001532 struct sem_undo_list *ulp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001534 ulp = tsk->sysvsem.undo_list;
1535 if (!ulp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 return;
Manfred Spraul9edff4a2008-04-29 01:00:57 -07001537 tsk->sysvsem.undo_list = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001539 if (!atomic_dec_and_test(&ulp->refcnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 return;
1541
Manfred Spraul380af1b2008-07-25 01:48:06 -07001542 for (;;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 struct sem_array *sma;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001544 struct sem_undo *un;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001545 struct list_head tasks;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001546 int semid;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001547 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548
Manfred Spraul380af1b2008-07-25 01:48:06 -07001549 rcu_read_lock();
Jiri Pirko05725f72009-04-14 20:17:16 +02001550 un = list_entry_rcu(ulp->list_proc.next,
1551 struct sem_undo, list_proc);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001552 if (&un->list_proc == &ulp->list_proc)
1553 semid = -1;
1554 else
1555 semid = un->semid;
1556 rcu_read_unlock();
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001557
Manfred Spraul380af1b2008-07-25 01:48:06 -07001558 if (semid == -1)
1559 break;
1560
1561 sma = sem_lock_check(tsk->nsproxy->ipc_ns, un->semid);
1562
1563 /* exit_sem raced with IPC_RMID, nothing to do */
Nadia Derbey023a5352007-10-18 23:40:51 -07001564 if (IS_ERR(sma))
Manfred Spraul380af1b2008-07-25 01:48:06 -07001565 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566
Nick Pigginbf17bb72009-12-15 16:47:28 -08001567 un = __lookup_undo(ulp, semid);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001568 if (un == NULL) {
1569 /* exit_sem raced with IPC_RMID+semget() that created
1570 * exactly the same semid. Nothing to do.
1571 */
1572 sem_unlock(sma);
1573 continue;
1574 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575
Manfred Spraul380af1b2008-07-25 01:48:06 -07001576 /* remove un from the linked lists */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001577 assert_spin_locked(&sma->sem_perm.lock);
1578 list_del(&un->list_id);
1579
Manfred Spraul380af1b2008-07-25 01:48:06 -07001580 spin_lock(&ulp->lock);
1581 list_del_rcu(&un->list_proc);
1582 spin_unlock(&ulp->lock);
1583
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001584 /* perform adjustments registered in un */
1585 for (i = 0; i < sma->sem_nsems; i++) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001586 struct sem * semaphore = &sma->sem_base[i];
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001587 if (un->semadj[i]) {
1588 semaphore->semval += un->semadj[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 /*
1590 * Range checks of the new semaphore value,
1591 * not defined by sus:
1592 * - Some unices ignore the undo entirely
1593 * (e.g. HP UX 11i 11.22, Tru64 V5.1)
1594 * - some cap the value (e.g. FreeBSD caps
1595 * at 0, but doesn't enforce SEMVMX)
1596 *
1597 * Linux caps the semaphore value, both at 0
1598 * and at SEMVMX.
1599 *
1600 * Manfred <manfred@colorfullife.com>
1601 */
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001602 if (semaphore->semval < 0)
1603 semaphore->semval = 0;
1604 if (semaphore->semval > SEMVMX)
1605 semaphore->semval = SEMVMX;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001606 semaphore->sempid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 }
1608 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 /* maybe some queued-up processes were waiting for this */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001610 INIT_LIST_HEAD(&tasks);
1611 do_smart_update(sma, NULL, 0, 1, &tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 sem_unlock(sma);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001613 wake_up_sem_queue_do(&tasks);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001614
1615 call_rcu(&un->rcu, free_un);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001617 kfree(ulp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618}
1619
1620#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -07001621static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622{
Mike Waychison19b49462005-09-06 15:17:10 -07001623 struct sem_array *sma = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624
Mike Waychison19b49462005-09-06 15:17:10 -07001625 return seq_printf(s,
Manfred Spraulb97e8202009-12-15 16:47:32 -08001626 "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
Mike Waychison19b49462005-09-06 15:17:10 -07001627 sma->sem_perm.key,
Nadia Derbey7ca7e562007-10-18 23:40:48 -07001628 sma->sem_perm.id,
Mike Waychison19b49462005-09-06 15:17:10 -07001629 sma->sem_perm.mode,
1630 sma->sem_nsems,
1631 sma->sem_perm.uid,
1632 sma->sem_perm.gid,
1633 sma->sem_perm.cuid,
1634 sma->sem_perm.cgid,
1635 sma->sem_otime,
1636 sma->sem_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637}
1638#endif