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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
Manfred Spraule57940d2011-11-02 13:38:54 -070093/* One semaphore structure for each semaphore in the system. */
94struct sem {
95 int semval; /* current value */
96 int sempid; /* pid of last operation */
Rik van Riel6062a8d2013-04-30 19:15:44 -070097 spinlock_t lock; /* spinlock for fine-grained semtimedop */
Manfred Spraule57940d2011-11-02 13:38:54 -070098 struct list_head sem_pending; /* pending single-sop operations */
99};
100
101/* One queue for each sleeping process in the system. */
102struct sem_queue {
Manfred Spraule57940d2011-11-02 13:38:54 -0700103 struct list_head list; /* queue of pending operations */
104 struct task_struct *sleeper; /* this process */
105 struct sem_undo *undo; /* undo structure */
106 int pid; /* process id of requesting process */
107 int status; /* completion status of operation */
108 struct sembuf *sops; /* array of pending operations */
109 int nsops; /* number of operations */
110 int alter; /* does *sops alter the array? */
111};
112
113/* Each task has a list of undo requests. They are executed automatically
114 * when the process exits.
115 */
116struct sem_undo {
117 struct list_head list_proc; /* per-process list: *
118 * all undos from one process
119 * rcu protected */
120 struct rcu_head rcu; /* rcu struct for sem_undo */
121 struct sem_undo_list *ulp; /* back ptr to sem_undo_list */
122 struct list_head list_id; /* per semaphore array list:
123 * all undos for one array */
124 int semid; /* semaphore set identifier */
125 short *semadj; /* array of adjustments */
126 /* one per semaphore */
127};
128
129/* sem_undo_list controls shared access to the list of sem_undo structures
130 * that may be shared among all a CLONE_SYSVSEM task group.
131 */
132struct sem_undo_list {
133 atomic_t refcnt;
134 spinlock_t lock;
135 struct list_head list_proc;
136};
137
138
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800139#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
Nadia Derbey1b531f22007-10-18 23:40:55 -0700141#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700143static int newary(struct ipc_namespace *, struct ipc_params *);
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800144static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700146static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147#endif
148
149#define SEMMSL_FAST 256 /* 512 bytes on stack */
150#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
151
152/*
153 * linked list protection:
154 * sem_undo.id_next,
155 * sem_array.sem_pending{,last},
156 * sem_array.sem_undo: sem_lock() for read/write
157 * sem_undo.proc_next: only "current" is allowed to read/write that field.
158 *
159 */
160
Kirill Korotaeve3893532006-10-02 02:18:22 -0700161#define sc_semmsl sem_ctls[0]
162#define sc_semmns sem_ctls[1]
163#define sc_semopm sem_ctls[2]
164#define sc_semmni sem_ctls[3]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800166void sem_init_ns(struct ipc_namespace *ns)
Kirill Korotaeve3893532006-10-02 02:18:22 -0700167{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700168 ns->sc_semmsl = SEMMSL;
169 ns->sc_semmns = SEMMNS;
170 ns->sc_semopm = SEMOPM;
171 ns->sc_semmni = SEMMNI;
172 ns->used_sems = 0;
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800173 ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700174}
175
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800176#ifdef CONFIG_IPC_NS
Kirill Korotaeve3893532006-10-02 02:18:22 -0700177void sem_exit_ns(struct ipc_namespace *ns)
178{
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800179 free_ipcs(ns, &sem_ids(ns), freeary);
Serge E. Hallyn7d6feeb2009-12-15 16:47:27 -0800180 idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700181}
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -0800182#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
184void __init sem_init (void)
185{
Pierre Peiffered2ddbf2008-02-08 04:18:57 -0800186 sem_init_ns(&init_ipc_ns);
Mike Waychison19b49462005-09-06 15:17:10 -0700187 ipc_init_proc_interface("sysvipc/sem",
188 " key semid perms nsems uid gid cuid cgid otime ctime\n",
Kirill Korotaeve3893532006-10-02 02:18:22 -0700189 IPC_SEM_IDS, sysvipc_sem_proc_show);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190}
191
Nadia Derbey3e148c72007-10-18 23:40:54 -0700192/*
Rik van Riel6062a8d2013-04-30 19:15:44 -0700193 * If the request contains only one semaphore operation, and there are
194 * no complex transactions pending, lock only the semaphore involved.
195 * Otherwise, lock the entire semaphore array, since we either have
196 * multiple semaphores in our own semops, or we need to look at
197 * semaphores from other pending complex operations.
198 *
199 * Carefully guard against sma->complex_count changing between zero
200 * and non-zero while we are spinning for the lock. The value of
201 * sma->complex_count cannot change while we are holding the lock,
202 * so sem_unlock should be fine.
203 *
204 * The global lock path checks that all the local locks have been released,
205 * checking each local lock once. This means that the local lock paths
206 * cannot start their critical sections while the global lock is held.
207 */
208static inline int sem_lock(struct sem_array *sma, struct sembuf *sops,
209 int nsops)
210{
211 int locknum;
212 again:
213 if (nsops == 1 && !sma->complex_count) {
214 struct sem *sem = sma->sem_base + sops->sem_num;
215
216 /* Lock just the semaphore we are interested in. */
217 spin_lock(&sem->lock);
218
219 /*
220 * If sma->complex_count was set while we were spinning,
221 * we may need to look at things we did not lock here.
222 */
223 if (unlikely(sma->complex_count)) {
224 spin_unlock(&sem->lock);
225 goto lock_array;
226 }
227
228 /*
229 * Another process is holding the global lock on the
230 * sem_array; we cannot enter our critical section,
231 * but have to wait for the global lock to be released.
232 */
233 if (unlikely(spin_is_locked(&sma->sem_perm.lock))) {
234 spin_unlock(&sem->lock);
235 spin_unlock_wait(&sma->sem_perm.lock);
236 goto again;
237 }
238
239 locknum = sops->sem_num;
240 } else {
241 int i;
242 /*
243 * Lock the semaphore array, and wait for all of the
244 * individual semaphore locks to go away. The code
245 * above ensures no new single-lock holders will enter
246 * their critical section while the array lock is held.
247 */
248 lock_array:
249 spin_lock(&sma->sem_perm.lock);
250 for (i = 0; i < sma->sem_nsems; i++) {
251 struct sem *sem = sma->sem_base + i;
252 spin_unlock_wait(&sem->lock);
253 }
254 locknum = -1;
255 }
256 return locknum;
257}
258
259static inline void sem_unlock(struct sem_array *sma, int locknum)
260{
261 if (locknum == -1) {
262 spin_unlock(&sma->sem_perm.lock);
263 } else {
264 struct sem *sem = sma->sem_base + locknum;
265 spin_unlock(&sem->lock);
266 }
Rik van Riel6062a8d2013-04-30 19:15:44 -0700267}
268
269/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700270 * sem_lock_(check_) routines are called in the paths where the rw_mutex
271 * is not held.
Linus Torvalds321310c2013-05-04 10:47:57 -0700272 *
273 * The caller holds the RCU read lock.
Nadia Derbey3e148c72007-10-18 23:40:54 -0700274 */
Rik van Riel6062a8d2013-04-30 19:15:44 -0700275static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns,
276 int id, struct sembuf *sops, int nsops, int *locknum)
Nadia Derbey023a5352007-10-18 23:40:51 -0700277{
Rik van Rielc460b662013-04-30 19:15:35 -0700278 struct kern_ipc_perm *ipcp;
279 struct sem_array *sma;
Nadia Derbey03f02c72007-10-18 23:40:51 -0700280
Rik van Rielc460b662013-04-30 19:15:35 -0700281 ipcp = ipc_obtain_object(&sem_ids(ns), id);
Linus Torvalds321310c2013-05-04 10:47:57 -0700282 if (IS_ERR(ipcp))
283 return ERR_CAST(ipcp);
Pierre Peifferb1ed88b2008-02-06 01:36:23 -0800284
Rik van Riel6062a8d2013-04-30 19:15:44 -0700285 sma = container_of(ipcp, struct sem_array, sem_perm);
286 *locknum = sem_lock(sma, sops, nsops);
Rik van Rielc460b662013-04-30 19:15:35 -0700287
288 /* ipc_rmid() may have already freed the ID while sem_lock
289 * was spinning: verify that the structure is still valid
290 */
291 if (!ipcp->deleted)
292 return container_of(ipcp, struct sem_array, sem_perm);
293
Rik van Riel6062a8d2013-04-30 19:15:44 -0700294 sem_unlock(sma, *locknum);
Linus Torvalds321310c2013-05-04 10:47:57 -0700295 return ERR_PTR(-EINVAL);
Nadia Derbey023a5352007-10-18 23:40:51 -0700296}
297
Davidlohr Bueso16df3672013-04-30 19:15:29 -0700298static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id)
299{
300 struct kern_ipc_perm *ipcp = ipc_obtain_object(&sem_ids(ns), id);
301
302 if (IS_ERR(ipcp))
303 return ERR_CAST(ipcp);
304
305 return container_of(ipcp, struct sem_array, sem_perm);
306}
307
Davidlohr Bueso16df3672013-04-30 19:15:29 -0700308static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns,
309 int id)
310{
311 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id);
312
313 if (IS_ERR(ipcp))
314 return ERR_CAST(ipcp);
Pierre Peifferb1ed88b2008-02-06 01:36:23 -0800315
Nadia Derbey03f02c72007-10-18 23:40:51 -0700316 return container_of(ipcp, struct sem_array, sem_perm);
Nadia Derbey023a5352007-10-18 23:40:51 -0700317}
318
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700319static inline void sem_lock_and_putref(struct sem_array *sma)
320{
Rik van Riel6062a8d2013-04-30 19:15:44 -0700321 sem_lock(sma, NULL, -1);
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700322 ipc_rcu_putref(sma);
323}
324
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700325static inline void sem_putref(struct sem_array *sma)
326{
Linus Torvalds73b29502013-05-03 15:22:00 -0700327 ipc_rcu_putref(sma);
Pierre Peiffer6ff37972008-04-29 01:00:46 -0700328}
329
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700330static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
331{
332 ipc_rmid(&sem_ids(ns), &s->sem_perm);
333}
334
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335/*
336 * Lockless wakeup algorithm:
337 * Without the check/retry algorithm a lockless wakeup is possible:
338 * - queue.status is initialized to -EINTR before blocking.
339 * - wakeup is performed by
340 * * unlinking the queue entry from sma->sem_pending
341 * * setting queue.status to IN_WAKEUP
342 * This is the notification for the blocked thread that a
343 * result value is imminent.
344 * * call wake_up_process
345 * * set queue.status to the final value.
346 * - the previously blocked thread checks queue.status:
347 * * if it's IN_WAKEUP, then it must wait until the value changes
348 * * if it's not -EINTR, then the operation was completed by
349 * update_queue. semtimedop can return queue.status without
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800350 * performing any operation on the sem array.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 * * otherwise it must acquire the spinlock and check what's up.
352 *
353 * The two-stage algorithm is necessary to protect against the following
354 * races:
355 * - if queue.status is set after wake_up_process, then the woken up idle
356 * thread could race forward and try (and fail) to acquire sma->lock
357 * before update_queue had a chance to set queue.status
358 * - if queue.status is written before wake_up_process and if the
359 * blocked process is woken up by a signal between writing
360 * queue.status and the wake_up_process, then the woken up
361 * process could return from semtimedop and die by calling
362 * sys_exit before wake_up_process is called. Then wake_up_process
363 * will oops, because the task structure is already invalid.
364 * (yes, this happened on s390 with sysv msg).
365 *
366 */
367#define IN_WAKEUP 1
368
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700369/**
370 * newary - Create a new semaphore set
371 * @ns: namespace
372 * @params: ptr to the structure that contains key, semflg and nsems
373 *
Nadia Derbey3e148c72007-10-18 23:40:54 -0700374 * Called with sem_ids.rw_mutex held (as a writer)
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700375 */
376
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700377static int newary(struct ipc_namespace *ns, struct ipc_params *params)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378{
379 int id;
380 int retval;
381 struct sem_array *sma;
382 int size;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700383 key_t key = params->key;
384 int nsems = params->u.nsems;
385 int semflg = params->flg;
Manfred Spraulb97e8202009-12-15 16:47:32 -0800386 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387
388 if (!nsems)
389 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700390 if (ns->used_sems + nsems > ns->sc_semmns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 return -ENOSPC;
392
393 size = sizeof (*sma) + nsems * sizeof (struct sem);
394 sma = ipc_rcu_alloc(size);
395 if (!sma) {
396 return -ENOMEM;
397 }
398 memset (sma, 0, size);
399
400 sma->sem_perm.mode = (semflg & S_IRWXUGO);
401 sma->sem_perm.key = key;
402
403 sma->sem_perm.security = NULL;
404 retval = security_sem_alloc(sma);
405 if (retval) {
406 ipc_rcu_putref(sma);
407 return retval;
408 }
409
Kirill Korotaeve3893532006-10-02 02:18:22 -0700410 id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
Pierre Peiffer283bb7f2007-10-18 23:40:57 -0700411 if (id < 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 security_sem_free(sma);
413 ipc_rcu_putref(sma);
Pierre Peiffer283bb7f2007-10-18 23:40:57 -0700414 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700416 ns->used_sems += nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417
418 sma->sem_base = (struct sem *) &sma[1];
Manfred Spraulb97e8202009-12-15 16:47:32 -0800419
Rik van Riel6062a8d2013-04-30 19:15:44 -0700420 for (i = 0; i < nsems; i++) {
Manfred Spraulb97e8202009-12-15 16:47:32 -0800421 INIT_LIST_HEAD(&sma->sem_base[i].sem_pending);
Rik van Riel6062a8d2013-04-30 19:15:44 -0700422 spin_lock_init(&sma->sem_base[i].lock);
423 }
Manfred Spraulb97e8202009-12-15 16:47:32 -0800424
425 sma->complex_count = 0;
Manfred Spraula1193f82008-07-25 01:48:06 -0700426 INIT_LIST_HEAD(&sma->sem_pending);
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700427 INIT_LIST_HEAD(&sma->list_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 sma->sem_nsems = nsems;
429 sma->sem_ctime = get_seconds();
Rik van Riel6062a8d2013-04-30 19:15:44 -0700430 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -0700431 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700433 return sma->sem_perm.id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434}
435
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700436
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700437/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700438 * Called with sem_ids.rw_mutex and ipcp locked.
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700439 */
Nadia Derbey03f02c72007-10-18 23:40:51 -0700440static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700442 struct sem_array *sma;
443
444 sma = container_of(ipcp, struct sem_array, sem_perm);
445 return security_sem_associate(sma, semflg);
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700446}
447
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700448/*
Nadia Derbey3e148c72007-10-18 23:40:54 -0700449 * Called with sem_ids.rw_mutex and ipcp locked.
Nadia Derbeyf4566f02007-10-18 23:40:53 -0700450 */
Nadia Derbey03f02c72007-10-18 23:40:51 -0700451static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
452 struct ipc_params *params)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700453{
Nadia Derbey03f02c72007-10-18 23:40:51 -0700454 struct sem_array *sma;
455
456 sma = container_of(ipcp, struct sem_array, sem_perm);
457 if (params->u.nsems > sma->sem_nsems)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700458 return -EINVAL;
459
460 return 0;
461}
462
Heiko Carstensd5460c92009-01-14 14:14:27 +0100463SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700464{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700465 struct ipc_namespace *ns;
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700466 struct ipc_ops sem_ops;
467 struct ipc_params sem_params;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468
Kirill Korotaeve3893532006-10-02 02:18:22 -0700469 ns = current->nsproxy->ipc_ns;
470
471 if (nsems < 0 || nsems > ns->sc_semmsl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 return -EINVAL;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700473
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700474 sem_ops.getnew = newary;
475 sem_ops.associate = sem_security;
476 sem_ops.more_checks = sem_more_checks;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700477
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700478 sem_params.key = key;
479 sem_params.flg = semflg;
480 sem_params.u.nsems = nsems;
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700481
Nadia Derbey7748dbf2007-10-18 23:40:49 -0700482 return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483}
484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485/*
486 * Determine whether a sequence of semaphore operations would succeed
487 * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
488 */
489
490static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
491 int nsops, struct sem_undo *un, int pid)
492{
493 int result, sem_op;
494 struct sembuf *sop;
495 struct sem * curr;
496
497 for (sop = sops; sop < sops + nsops; sop++) {
498 curr = sma->sem_base + sop->sem_num;
499 sem_op = sop->sem_op;
500 result = curr->semval;
501
502 if (!sem_op && result)
503 goto would_block;
504
505 result += sem_op;
506 if (result < 0)
507 goto would_block;
508 if (result > SEMVMX)
509 goto out_of_range;
510 if (sop->sem_flg & SEM_UNDO) {
511 int undo = un->semadj[sop->sem_num] - sem_op;
512 /*
513 * Exceeding the undo range is an error.
514 */
515 if (undo < (-SEMAEM - 1) || undo > SEMAEM)
516 goto out_of_range;
517 }
518 curr->semval = result;
519 }
520
521 sop--;
522 while (sop >= sops) {
523 sma->sem_base[sop->sem_num].sempid = pid;
524 if (sop->sem_flg & SEM_UNDO)
525 un->semadj[sop->sem_num] -= sop->sem_op;
526 sop--;
527 }
528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 return 0;
530
531out_of_range:
532 result = -ERANGE;
533 goto undo;
534
535would_block:
536 if (sop->sem_flg & IPC_NOWAIT)
537 result = -EAGAIN;
538 else
539 result = 1;
540
541undo:
542 sop--;
543 while (sop >= sops) {
544 sma->sem_base[sop->sem_num].semval -= sop->sem_op;
545 sop--;
546 }
547
548 return result;
549}
550
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700551/** wake_up_sem_queue_prepare(q, error): Prepare wake-up
552 * @q: queue entry that must be signaled
553 * @error: Error value for the signal
554 *
555 * Prepare the wake-up of the queue entry q.
Nick Piggind4212092009-12-15 16:47:30 -0800556 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700557static void wake_up_sem_queue_prepare(struct list_head *pt,
558 struct sem_queue *q, int error)
Nick Piggind4212092009-12-15 16:47:30 -0800559{
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700560 if (list_empty(pt)) {
561 /*
562 * Hold preempt off so that we don't get preempted and have the
563 * wakee busy-wait until we're scheduled back on.
564 */
565 preempt_disable();
566 }
Nick Piggind4212092009-12-15 16:47:30 -0800567 q->status = IN_WAKEUP;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700568 q->pid = error;
569
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700570 list_add_tail(&q->list, pt);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700571}
572
573/**
574 * wake_up_sem_queue_do(pt) - do the actual wake-up
575 * @pt: list of tasks to be woken up
576 *
577 * Do the actual wake-up.
578 * The function is called without any locks held, thus the semaphore array
579 * could be destroyed already and the tasks can disappear as soon as the
580 * status is set to the actual return code.
581 */
582static void wake_up_sem_queue_do(struct list_head *pt)
583{
584 struct sem_queue *q, *t;
585 int did_something;
586
587 did_something = !list_empty(pt);
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700588 list_for_each_entry_safe(q, t, pt, list) {
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700589 wake_up_process(q->sleeper);
590 /* q can disappear immediately after writing q->status. */
591 smp_wmb();
592 q->status = q->pid;
593 }
594 if (did_something)
595 preempt_enable();
Nick Piggind4212092009-12-15 16:47:30 -0800596}
597
Manfred Spraulb97e8202009-12-15 16:47:32 -0800598static void unlink_queue(struct sem_array *sma, struct sem_queue *q)
599{
600 list_del(&q->list);
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700601 if (q->nsops > 1)
Manfred Spraulb97e8202009-12-15 16:47:32 -0800602 sma->complex_count--;
603}
604
Manfred Spraulfd5db422010-05-26 14:43:40 -0700605/** check_restart(sma, q)
606 * @sma: semaphore array
607 * @q: the operation that just completed
608 *
609 * update_queue is O(N^2) when it restarts scanning the whole queue of
610 * waiting operations. Therefore this function checks if the restart is
611 * really necessary. It is called after a previously waiting operation
612 * was completed.
613 */
614static int check_restart(struct sem_array *sma, struct sem_queue *q)
615{
616 struct sem *curr;
617 struct sem_queue *h;
618
619 /* if the operation didn't modify the array, then no restart */
620 if (q->alter == 0)
621 return 0;
622
623 /* pending complex operations are too difficult to analyse */
624 if (sma->complex_count)
625 return 1;
626
627 /* we were a sleeping complex operation. Too difficult */
628 if (q->nsops > 1)
629 return 1;
630
631 curr = sma->sem_base + q->sops[0].sem_num;
632
633 /* No-one waits on this queue */
634 if (list_empty(&curr->sem_pending))
635 return 0;
636
637 /* the new semaphore value */
638 if (curr->semval) {
639 /* It is impossible that someone waits for the new value:
640 * - q is a previously sleeping simple operation that
641 * altered the array. It must be a decrement, because
642 * simple increments never sleep.
643 * - The value is not 0, thus wait-for-zero won't proceed.
644 * - If there are older (higher priority) decrements
645 * in the queue, then they have observed the original
646 * semval value and couldn't proceed. The operation
647 * decremented to value - thus they won't proceed either.
648 */
649 BUG_ON(q->sops[0].sem_op >= 0);
650 return 0;
651 }
652 /*
653 * semval is 0. Check if there are wait-for-zero semops.
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700654 * They must be the first entries in the per-semaphore queue
Manfred Spraulfd5db422010-05-26 14:43:40 -0700655 */
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700656 h = list_first_entry(&curr->sem_pending, struct sem_queue, list);
Manfred Spraulfd5db422010-05-26 14:43:40 -0700657 BUG_ON(h->nsops != 1);
658 BUG_ON(h->sops[0].sem_num != q->sops[0].sem_num);
659
660 /* Yes, there is a wait-for-zero semop. Restart */
661 if (h->sops[0].sem_op == 0)
662 return 1;
663
664 /* Again - no-one is waiting for the new value. */
665 return 0;
666}
667
Manfred Spraul636c6be2009-12-15 16:47:33 -0800668
669/**
670 * update_queue(sma, semnum): Look for tasks that can be completed.
671 * @sma: semaphore array.
672 * @semnum: semaphore that was modified.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700673 * @pt: list head for the tasks that must be woken up.
Manfred Spraul636c6be2009-12-15 16:47:33 -0800674 *
675 * update_queue must be called after a semaphore in a semaphore array
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700676 * was modified. If multiple semaphores were modified, update_queue must
677 * be called with semnum = -1, as well as with the number of each modified
678 * semaphore.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700679 * The tasks that must be woken up are added to @pt. The return code
680 * is stored in q->pid.
681 * The function return 1 if at least one semop was completed successfully.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700683static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684{
Manfred Spraul636c6be2009-12-15 16:47:33 -0800685 struct sem_queue *q;
686 struct list_head *walk;
687 struct list_head *pending_list;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700688 int semop_completed = 0;
Manfred Spraul636c6be2009-12-15 16:47:33 -0800689
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700690 if (semnum == -1)
Manfred Spraul636c6be2009-12-15 16:47:33 -0800691 pending_list = &sma->sem_pending;
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700692 else
Manfred Spraul636c6be2009-12-15 16:47:33 -0800693 pending_list = &sma->sem_base[semnum].sem_pending;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694
Nick Piggin9cad2002009-12-15 16:47:29 -0800695again:
Manfred Spraul636c6be2009-12-15 16:47:33 -0800696 walk = pending_list->next;
697 while (walk != pending_list) {
Manfred Spraulfd5db422010-05-26 14:43:40 -0700698 int error, restart;
Manfred Spraul636c6be2009-12-15 16:47:33 -0800699
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700700 q = container_of(walk, struct sem_queue, list);
Manfred Spraul636c6be2009-12-15 16:47:33 -0800701 walk = walk->next;
Nick Piggin9cad2002009-12-15 16:47:29 -0800702
Manfred Sprauld987f8b2009-12-15 16:47:34 -0800703 /* If we are scanning the single sop, per-semaphore list of
704 * one semaphore and that semaphore is 0, then it is not
705 * necessary to scan the "alter" entries: simple increments
706 * that affect only one entry succeed immediately and cannot
707 * be in the per semaphore pending queue, and decrements
708 * cannot be successful if the value is already 0.
709 */
710 if (semnum != -1 && sma->sem_base[semnum].semval == 0 &&
711 q->alter)
712 break;
713
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 error = try_atomic_semop(sma, q->sops, q->nsops,
715 q->undo, q->pid);
716
717 /* Does q->sleeper still need to sleep? */
Nick Piggin9cad2002009-12-15 16:47:29 -0800718 if (error > 0)
719 continue;
Manfred Spraula1193f82008-07-25 01:48:06 -0700720
Manfred Spraulb97e8202009-12-15 16:47:32 -0800721 unlink_queue(sma, q);
Manfred Spraula1193f82008-07-25 01:48:06 -0700722
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700723 if (error) {
Manfred Spraulfd5db422010-05-26 14:43:40 -0700724 restart = 0;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700725 } else {
726 semop_completed = 1;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700727 restart = check_restart(sma, q);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700728 }
Manfred Spraulfd5db422010-05-26 14:43:40 -0700729
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700730 wake_up_sem_queue_prepare(pt, q, error);
Manfred Spraulfd5db422010-05-26 14:43:40 -0700731 if (restart)
Nick Piggin9cad2002009-12-15 16:47:29 -0800732 goto again;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 }
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700734 return semop_completed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735}
736
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700737/**
738 * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue
Manfred Spraulfd5db422010-05-26 14:43:40 -0700739 * @sma: semaphore array
740 * @sops: operations that were performed
741 * @nsops: number of operations
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700742 * @otime: force setting otime
743 * @pt: list head of the tasks that must be woken up.
Manfred Spraulfd5db422010-05-26 14:43:40 -0700744 *
745 * do_smart_update() does the required called to update_queue, based on the
746 * actual changes that were performed on the semaphore array.
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700747 * Note that the function does not do the actual wake-up: the caller is
748 * responsible for calling wake_up_sem_queue_do(@pt).
749 * It is safe to perform this call after dropping all locks.
Manfred Spraulfd5db422010-05-26 14:43:40 -0700750 */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700751static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops,
752 int otime, struct list_head *pt)
Manfred Spraulfd5db422010-05-26 14:43:40 -0700753{
754 int i;
Manfred Spraulab465df2013-05-26 11:08:52 +0200755 int progress;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700756
Manfred Spraulab465df2013-05-26 11:08:52 +0200757 progress = 1;
758retry_global:
759 if (sma->complex_count) {
760 if (update_queue(sma, -1, pt)) {
761 progress = 1;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700762 otime = 1;
Manfred Spraulab465df2013-05-26 11:08:52 +0200763 sops = NULL;
764 }
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700765 }
Manfred Spraulab465df2013-05-26 11:08:52 +0200766 if (!progress)
767 goto done;
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700768
769 if (!sops) {
770 /* No semops; something special is going on. */
771 for (i = 0; i < sma->sem_nsems; i++) {
Manfred Spraulab465df2013-05-26 11:08:52 +0200772 if (update_queue(sma, i, pt)) {
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700773 otime = 1;
Manfred Spraulab465df2013-05-26 11:08:52 +0200774 progress = 1;
775 }
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700776 }
Manfred Spraulab465df2013-05-26 11:08:52 +0200777 goto done_checkretry;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700778 }
779
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700780 /* Check the semaphores that were modified. */
Manfred Spraulfd5db422010-05-26 14:43:40 -0700781 for (i = 0; i < nsops; i++) {
782 if (sops[i].sem_op > 0 ||
783 (sops[i].sem_op < 0 &&
784 sma->sem_base[sops[i].sem_num].semval == 0))
Manfred Spraulab465df2013-05-26 11:08:52 +0200785 if (update_queue(sma, sops[i].sem_num, pt)) {
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700786 otime = 1;
Manfred Spraulab465df2013-05-26 11:08:52 +0200787 progress = 1;
788 }
789 }
790done_checkretry:
791 if (progress) {
792 progress = 0;
793 goto retry_global;
Manfred Spraulfd5db422010-05-26 14:43:40 -0700794 }
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700795done:
796 if (otime)
797 sma->sem_otime = get_seconds();
Manfred Spraulfd5db422010-05-26 14:43:40 -0700798}
799
800
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801/* The following counts are associated to each semaphore:
802 * semncnt number of tasks waiting on semval being nonzero
803 * semzcnt number of tasks waiting on semval being zero
804 * This model assumes that a task waits on exactly one semaphore.
805 * Since semaphore operations are to be performed atomically, tasks actually
806 * wait on a whole sequence of semaphores simultaneously.
807 * The counts we return here are a rough approximation, but still
808 * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
809 */
810static int count_semncnt (struct sem_array * sma, ushort semnum)
811{
812 int semncnt;
813 struct sem_queue * q;
814
815 semncnt = 0;
Rik van Rielde2657f2013-05-09 16:59:59 -0400816 list_for_each_entry(q, &sma->sem_base[semnum].sem_pending, list) {
817 struct sembuf * sops = q->sops;
818 BUG_ON(sops->sem_num != semnum);
819 if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT))
820 semncnt++;
821 }
822
Manfred Spraula1193f82008-07-25 01:48:06 -0700823 list_for_each_entry(q, &sma->sem_pending, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 struct sembuf * sops = q->sops;
825 int nsops = q->nsops;
826 int i;
827 for (i = 0; i < nsops; i++)
828 if (sops[i].sem_num == semnum
829 && (sops[i].sem_op < 0)
830 && !(sops[i].sem_flg & IPC_NOWAIT))
831 semncnt++;
832 }
833 return semncnt;
834}
Manfred Spraula1193f82008-07-25 01:48:06 -0700835
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836static int count_semzcnt (struct sem_array * sma, ushort semnum)
837{
838 int semzcnt;
839 struct sem_queue * q;
840
841 semzcnt = 0;
Rik van Rielebc2e5e2013-05-09 16:53:28 -0400842 list_for_each_entry(q, &sma->sem_base[semnum].sem_pending, list) {
843 struct sembuf * sops = q->sops;
844 BUG_ON(sops->sem_num != semnum);
845 if ((sops->sem_op == 0) && !(sops->sem_flg & IPC_NOWAIT))
846 semzcnt++;
847 }
848
Manfred Spraula1193f82008-07-25 01:48:06 -0700849 list_for_each_entry(q, &sma->sem_pending, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 struct sembuf * sops = q->sops;
851 int nsops = q->nsops;
852 int i;
853 for (i = 0; i < nsops; i++)
854 if (sops[i].sem_num == semnum
855 && (sops[i].sem_op == 0)
856 && !(sops[i].sem_flg & IPC_NOWAIT))
857 semzcnt++;
858 }
859 return semzcnt;
860}
861
Nadia Derbey3e148c72007-10-18 23:40:54 -0700862/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
863 * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
864 * remains locked on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 */
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800866static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867{
Manfred Spraul380af1b2008-07-25 01:48:06 -0700868 struct sem_undo *un, *tu;
869 struct sem_queue *q, *tq;
Pierre Peiffer01b8b072008-02-08 04:18:57 -0800870 struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700871 struct list_head tasks;
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700872 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873
Manfred Spraul380af1b2008-07-25 01:48:06 -0700874 /* Free the existing undo structures for this semaphore set. */
Manfred Spraul4daa28f2008-07-25 01:48:04 -0700875 assert_spin_locked(&sma->sem_perm.lock);
Manfred Spraul380af1b2008-07-25 01:48:06 -0700876 list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
877 list_del(&un->list_id);
878 spin_lock(&un->ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 un->semid = -1;
Manfred Spraul380af1b2008-07-25 01:48:06 -0700880 list_del_rcu(&un->list_proc);
881 spin_unlock(&un->ulp->lock);
Lai Jiangshan693a8b62011-03-18 12:09:35 +0800882 kfree_rcu(un, rcu);
Manfred Spraul380af1b2008-07-25 01:48:06 -0700883 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884
885 /* Wake up all pending processes and let them fail with EIDRM. */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700886 INIT_LIST_HEAD(&tasks);
Manfred Spraul380af1b2008-07-25 01:48:06 -0700887 list_for_each_entry_safe(q, tq, &sma->sem_pending, list) {
Manfred Spraulb97e8202009-12-15 16:47:32 -0800888 unlink_queue(sma, q);
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700889 wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 }
Rik van Riel9f1bc2c92013-04-30 19:15:39 -0700891 for (i = 0; i < sma->sem_nsems; i++) {
892 struct sem *sem = sma->sem_base + i;
893 list_for_each_entry_safe(q, tq, &sem->sem_pending, list) {
894 unlink_queue(sma, q);
895 wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
896 }
897 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700899 /* Remove the semaphore set from the IDR */
900 sem_rmid(ns, sma);
Rik van Riel6062a8d2013-04-30 19:15:44 -0700901 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -0700902 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
Manfred Spraul0a2b9d42010-05-26 14:43:41 -0700904 wake_up_sem_queue_do(&tasks);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700905 ns->used_sems -= sma->sem_nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 security_sem_free(sma);
907 ipc_rcu_putref(sma);
908}
909
910static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
911{
912 switch(version) {
913 case IPC_64:
914 return copy_to_user(buf, in, sizeof(*in));
915 case IPC_OLD:
916 {
917 struct semid_ds out;
918
Dan Rosenberg982f7c22010-09-30 15:15:31 -0700919 memset(&out, 0, sizeof(out));
920
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
922
923 out.sem_otime = in->sem_otime;
924 out.sem_ctime = in->sem_ctime;
925 out.sem_nsems = in->sem_nsems;
926
927 return copy_to_user(buf, &out, sizeof(out));
928 }
929 default:
930 return -EINVAL;
931 }
932}
933
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800934static int semctl_nolock(struct ipc_namespace *ns, int semid,
Al Viroe1fd1f42013-03-05 15:04:55 -0500935 int cmd, int version, void __user *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936{
Amerigo Wange5cc9c72009-12-15 16:47:35 -0800937 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938 struct sem_array *sma;
939
940 switch(cmd) {
941 case IPC_INFO:
942 case SEM_INFO:
943 {
944 struct seminfo seminfo;
945 int max_id;
946
947 err = security_sem_semctl(NULL, cmd);
948 if (err)
949 return err;
950
951 memset(&seminfo,0,sizeof(seminfo));
Kirill Korotaeve3893532006-10-02 02:18:22 -0700952 seminfo.semmni = ns->sc_semmni;
953 seminfo.semmns = ns->sc_semmns;
954 seminfo.semmsl = ns->sc_semmsl;
955 seminfo.semopm = ns->sc_semopm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 seminfo.semvmx = SEMVMX;
957 seminfo.semmnu = SEMMNU;
958 seminfo.semmap = SEMMAP;
959 seminfo.semume = SEMUME;
Nadia Derbey3e148c72007-10-18 23:40:54 -0700960 down_read(&sem_ids(ns).rw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 if (cmd == SEM_INFO) {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700962 seminfo.semusz = sem_ids(ns).in_use;
963 seminfo.semaem = ns->used_sems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 } else {
965 seminfo.semusz = SEMUSZ;
966 seminfo.semaem = SEMAEM;
967 }
Nadia Derbey7ca7e562007-10-18 23:40:48 -0700968 max_id = ipc_get_maxid(&sem_ids(ns));
Nadia Derbey3e148c72007-10-18 23:40:54 -0700969 up_read(&sem_ids(ns).rw_mutex);
Al Viroe1fd1f42013-03-05 15:04:55 -0500970 if (copy_to_user(p, &seminfo, sizeof(struct seminfo)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 return -EFAULT;
972 return (max_id < 0) ? 0: max_id;
973 }
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800974 case IPC_STAT:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 case SEM_STAT:
976 {
977 struct semid64_ds tbuf;
Davidlohr Bueso16df3672013-04-30 19:15:29 -0700978 int id = 0;
979
980 memset(&tbuf, 0, sizeof(tbuf));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
Linus Torvalds941b0302013-05-04 11:04:29 -0700982 rcu_read_lock();
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800983 if (cmd == SEM_STAT) {
Davidlohr Bueso16df3672013-04-30 19:15:29 -0700984 sma = sem_obtain_object(ns, semid);
985 if (IS_ERR(sma)) {
986 err = PTR_ERR(sma);
987 goto out_unlock;
988 }
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800989 id = sma->sem_perm.id;
990 } else {
Davidlohr Bueso16df3672013-04-30 19:15:29 -0700991 sma = sem_obtain_object_check(ns, semid);
992 if (IS_ERR(sma)) {
993 err = PTR_ERR(sma);
994 goto out_unlock;
995 }
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -0800996 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997
998 err = -EACCES;
Serge E. Hallynb0e77592011-03-23 16:43:24 -0700999 if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 goto out_unlock;
1001
1002 err = security_sem_semctl(sma, cmd);
1003 if (err)
1004 goto out_unlock;
1005
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
1007 tbuf.sem_otime = sma->sem_otime;
1008 tbuf.sem_ctime = sma->sem_ctime;
1009 tbuf.sem_nsems = sma->sem_nsems;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001010 rcu_read_unlock();
Al Viroe1fd1f42013-03-05 15:04:55 -05001011 if (copy_semid_to_user(p, &tbuf, version))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 return -EFAULT;
1013 return id;
1014 }
1015 default:
1016 return -EINVAL;
1017 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018out_unlock:
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001019 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 return err;
1021}
1022
Al Viroe1fd1f42013-03-05 15:04:55 -05001023static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
1024 unsigned long arg)
1025{
1026 struct sem_undo *un;
1027 struct sem_array *sma;
1028 struct sem* curr;
1029 int err;
Al Viroe1fd1f42013-03-05 15:04:55 -05001030 struct list_head tasks;
1031 int val;
1032#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
1033 /* big-endian 64bit */
1034 val = arg >> 32;
1035#else
1036 /* 32bit or little-endian 64bit */
1037 val = arg;
1038#endif
1039
Rik van Riel6062a8d2013-04-30 19:15:44 -07001040 if (val > SEMVMX || val < 0)
1041 return -ERANGE;
Al Viroe1fd1f42013-03-05 15:04:55 -05001042
1043 INIT_LIST_HEAD(&tasks);
Al Viroe1fd1f42013-03-05 15:04:55 -05001044
Rik van Riel6062a8d2013-04-30 19:15:44 -07001045 rcu_read_lock();
1046 sma = sem_obtain_object_check(ns, semid);
1047 if (IS_ERR(sma)) {
1048 rcu_read_unlock();
1049 return PTR_ERR(sma);
1050 }
1051
1052 if (semnum < 0 || semnum >= sma->sem_nsems) {
1053 rcu_read_unlock();
1054 return -EINVAL;
1055 }
1056
1057
1058 if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) {
1059 rcu_read_unlock();
1060 return -EACCES;
1061 }
Al Viroe1fd1f42013-03-05 15:04:55 -05001062
1063 err = security_sem_semctl(sma, SETVAL);
Rik van Riel6062a8d2013-04-30 19:15:44 -07001064 if (err) {
1065 rcu_read_unlock();
1066 return -EACCES;
1067 }
Al Viroe1fd1f42013-03-05 15:04:55 -05001068
Rik van Riel6062a8d2013-04-30 19:15:44 -07001069 sem_lock(sma, NULL, -1);
Al Viroe1fd1f42013-03-05 15:04:55 -05001070
1071 curr = &sma->sem_base[semnum];
1072
Al Viroe1fd1f42013-03-05 15:04:55 -05001073 assert_spin_locked(&sma->sem_perm.lock);
1074 list_for_each_entry(un, &sma->list_id, list_id)
1075 un->semadj[semnum] = 0;
1076
1077 curr->semval = val;
1078 curr->sempid = task_tgid_vnr(current);
1079 sma->sem_ctime = get_seconds();
1080 /* maybe some queued-up processes were waiting for this */
1081 do_smart_update(sma, NULL, 0, 0, &tasks);
Rik van Riel6062a8d2013-04-30 19:15:44 -07001082 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001083 rcu_read_unlock();
Al Viroe1fd1f42013-03-05 15:04:55 -05001084 wake_up_sem_queue_do(&tasks);
Rik van Riel6062a8d2013-04-30 19:15:44 -07001085 return 0;
Al Viroe1fd1f42013-03-05 15:04:55 -05001086}
1087
Kirill Korotaeve3893532006-10-02 02:18:22 -07001088static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
Al Viroe1fd1f42013-03-05 15:04:55 -05001089 int cmd, void __user *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090{
1091 struct sem_array *sma;
1092 struct sem* curr;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001093 int err, nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 ushort fast_sem_io[SEMMSL_FAST];
1095 ushort* sem_io = fast_sem_io;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001096 struct list_head tasks;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001098 INIT_LIST_HEAD(&tasks);
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001099
1100 rcu_read_lock();
1101 sma = sem_obtain_object_check(ns, semid);
1102 if (IS_ERR(sma)) {
1103 rcu_read_unlock();
1104 return PTR_ERR(sma);
1105 }
1106
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 nsems = sma->sem_nsems;
1108
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 err = -EACCES;
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001110 if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
1111 goto out_rcu_wakeup;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112
1113 err = security_sem_semctl(sma, cmd);
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001114 if (err)
1115 goto out_rcu_wakeup;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
1117 err = -EACCES;
1118 switch (cmd) {
1119 case GETALL:
1120 {
Al Viroe1fd1f42013-03-05 15:04:55 -05001121 ushort __user *array = p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 int i;
1123
Al Viroce857222013-05-03 00:30:49 +01001124 sem_lock(sma, NULL, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 if(nsems > SEMMSL_FAST) {
Al Viroce857222013-05-03 00:30:49 +01001126 if (!ipc_rcu_getref(sma)) {
1127 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001128 rcu_read_unlock();
Al Viroce857222013-05-03 00:30:49 +01001129 err = -EIDRM;
1130 goto out_free;
1131 }
1132 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001133 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 sem_io = ipc_alloc(sizeof(ushort)*nsems);
1135 if(sem_io == NULL) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001136 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 return -ENOMEM;
1138 }
1139
Linus Torvalds4091fd92013-05-04 10:13:40 -07001140 rcu_read_lock();
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001141 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 if (sma->sem_perm.deleted) {
Rik van Riel6062a8d2013-04-30 19:15:44 -07001143 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001144 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 err = -EIDRM;
1146 goto out_free;
1147 }
Al Viroce857222013-05-03 00:30:49 +01001148 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 for (i = 0; i < sma->sem_nsems; i++)
1150 sem_io[i] = sma->sem_base[i].semval;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001151 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001152 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 err = 0;
1154 if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
1155 err = -EFAULT;
1156 goto out_free;
1157 }
1158 case SETALL:
1159 {
1160 int i;
1161 struct sem_undo *un;
1162
Rik van Riel6062a8d2013-04-30 19:15:44 -07001163 if (!ipc_rcu_getref(sma)) {
1164 rcu_read_unlock();
1165 return -EIDRM;
1166 }
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001167 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
1169 if(nsems > SEMMSL_FAST) {
1170 sem_io = ipc_alloc(sizeof(ushort)*nsems);
1171 if(sem_io == NULL) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001172 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 return -ENOMEM;
1174 }
1175 }
1176
Al Viroe1fd1f42013-03-05 15:04:55 -05001177 if (copy_from_user (sem_io, p, nsems*sizeof(ushort))) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001178 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 err = -EFAULT;
1180 goto out_free;
1181 }
1182
1183 for (i = 0; i < nsems; i++) {
1184 if (sem_io[i] > SEMVMX) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001185 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 err = -ERANGE;
1187 goto out_free;
1188 }
1189 }
Linus Torvalds4091fd92013-05-04 10:13:40 -07001190 rcu_read_lock();
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001191 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 if (sma->sem_perm.deleted) {
Rik van Riel6062a8d2013-04-30 19:15:44 -07001193 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001194 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 err = -EIDRM;
1196 goto out_free;
1197 }
1198
1199 for (i = 0; i < nsems; i++)
1200 sma->sem_base[i].semval = sem_io[i];
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001201
1202 assert_spin_locked(&sma->sem_perm.lock);
1203 list_for_each_entry(un, &sma->list_id, list_id) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 for (i = 0; i < nsems; i++)
1205 un->semadj[i] = 0;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001206 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 sma->sem_ctime = get_seconds();
1208 /* maybe some queued-up processes were waiting for this */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001209 do_smart_update(sma, NULL, 0, 0, &tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 err = 0;
1211 goto out_unlock;
1212 }
Al Viroe1fd1f42013-03-05 15:04:55 -05001213 /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 }
1215 err = -EINVAL;
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001216 if (semnum < 0 || semnum >= nsems)
1217 goto out_rcu_wakeup;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218
Rik van Riel6062a8d2013-04-30 19:15:44 -07001219 sem_lock(sma, NULL, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 curr = &sma->sem_base[semnum];
1221
1222 switch (cmd) {
1223 case GETVAL:
1224 err = curr->semval;
1225 goto out_unlock;
1226 case GETPID:
1227 err = curr->sempid;
1228 goto out_unlock;
1229 case GETNCNT:
1230 err = count_semncnt(sma,semnum);
1231 goto out_unlock;
1232 case GETZCNT:
1233 err = count_semzcnt(sma,semnum);
1234 goto out_unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 }
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001236
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237out_unlock:
Rik van Riel6062a8d2013-04-30 19:15:44 -07001238 sem_unlock(sma, -1);
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001239out_rcu_wakeup:
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001240 rcu_read_unlock();
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001241 wake_up_sem_queue_do(&tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242out_free:
1243 if(sem_io != fast_sem_io)
1244 ipc_free(sem_io, sizeof(ushort)*nsems);
1245 return err;
1246}
1247
Pierre Peiffer016d7132008-04-29 01:00:50 -07001248static inline unsigned long
1249copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250{
1251 switch(version) {
1252 case IPC_64:
Pierre Peiffer016d7132008-04-29 01:00:50 -07001253 if (copy_from_user(out, buf, sizeof(*out)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 case IPC_OLD:
1257 {
1258 struct semid_ds tbuf_old;
1259
1260 if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
1261 return -EFAULT;
1262
Pierre Peiffer016d7132008-04-29 01:00:50 -07001263 out->sem_perm.uid = tbuf_old.sem_perm.uid;
1264 out->sem_perm.gid = tbuf_old.sem_perm.gid;
1265 out->sem_perm.mode = tbuf_old.sem_perm.mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266
1267 return 0;
1268 }
1269 default:
1270 return -EINVAL;
1271 }
1272}
1273
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001274/*
1275 * This function handles some semctl commands which require the rw_mutex
1276 * to be held in write mode.
1277 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
1278 */
Pierre Peiffer21a48262008-04-29 01:00:49 -07001279static int semctl_down(struct ipc_namespace *ns, int semid,
Al Viroe1fd1f42013-03-05 15:04:55 -05001280 int cmd, int version, void __user *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281{
1282 struct sem_array *sma;
1283 int err;
Pierre Peiffer016d7132008-04-29 01:00:50 -07001284 struct semid64_ds semid64;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 struct kern_ipc_perm *ipcp;
1286
1287 if(cmd == IPC_SET) {
Al Viroe1fd1f42013-03-05 15:04:55 -05001288 if (copy_semid_from_user(&semid64, p, version))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001292 ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd,
1293 &semid64.sem_perm, 0);
Pierre Peiffera5f75e72008-04-29 01:00:54 -07001294 if (IS_ERR(ipcp))
1295 return PTR_ERR(ipcp);
Steve Grubb073115d2006-04-02 17:07:33 -04001296
Pierre Peiffera5f75e72008-04-29 01:00:54 -07001297 sma = container_of(ipcp, struct sem_array, sem_perm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298
1299 err = security_sem_semctl(sma, cmd);
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001300 if (err) {
1301 rcu_read_unlock();
Linus Torvaldsfbfd1d22013-05-04 10:25:11 -07001302 goto out_up;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001303 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304
1305 switch(cmd){
1306 case IPC_RMID:
Rik van Riel6062a8d2013-04-30 19:15:44 -07001307 sem_lock(sma, NULL, -1);
Pierre Peiffer01b8b072008-02-08 04:18:57 -08001308 freeary(ns, ipcp);
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001309 goto out_up;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 case IPC_SET:
Rik van Riel6062a8d2013-04-30 19:15:44 -07001311 sem_lock(sma, NULL, -1);
Eric W. Biederman1efdb692012-02-07 16:54:11 -08001312 err = ipc_update_perm(&semid64.sem_perm, ipcp);
1313 if (err)
1314 goto out_unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 sma->sem_ctime = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 break;
1317 default:
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001318 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 err = -EINVAL;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001320 goto out_up;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322
1323out_unlock:
Rik van Riel6062a8d2013-04-30 19:15:44 -07001324 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001325 rcu_read_unlock();
Pierre Peiffer522bb2a2008-04-29 01:00:49 -07001326out_up:
1327 up_write(&sem_ids(ns).rw_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 return err;
1329}
1330
Al Viroe1fd1f42013-03-05 15:04:55 -05001331SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 int version;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001334 struct ipc_namespace *ns;
Al Viroe1fd1f42013-03-05 15:04:55 -05001335 void __user *p = (void __user *)arg;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336
1337 if (semid < 0)
1338 return -EINVAL;
1339
1340 version = ipc_parse_version(&cmd);
Kirill Korotaeve3893532006-10-02 02:18:22 -07001341 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
1343 switch(cmd) {
1344 case IPC_INFO:
1345 case SEM_INFO:
Pierre Peiffer4b9fcb02008-02-08 04:18:56 -08001346 case IPC_STAT:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 case SEM_STAT:
Al Viroe1fd1f42013-03-05 15:04:55 -05001348 return semctl_nolock(ns, semid, cmd, version, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 case GETALL:
1350 case GETVAL:
1351 case GETPID:
1352 case GETNCNT:
1353 case GETZCNT:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 case SETALL:
Al Viroe1fd1f42013-03-05 15:04:55 -05001355 return semctl_main(ns, semid, semnum, cmd, p);
1356 case SETVAL:
1357 return semctl_setval(ns, semid, semnum, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 case IPC_RMID:
1359 case IPC_SET:
Al Viroe1fd1f42013-03-05 15:04:55 -05001360 return semctl_down(ns, semid, cmd, version, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 default:
1362 return -EINVAL;
1363 }
1364}
1365
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366/* If the task doesn't already have a undo_list, then allocate one
1367 * here. We guarantee there is only one thread using this undo list,
1368 * and current is THE ONE
1369 *
1370 * If this allocation and assignment succeeds, but later
1371 * portions of this code fail, there is no need to free the sem_undo_list.
1372 * Just let it stay associated with the task, and it'll be freed later
1373 * at exit time.
1374 *
1375 * This can block, so callers must hold no locks.
1376 */
1377static inline int get_undo_list(struct sem_undo_list **undo_listp)
1378{
1379 struct sem_undo_list *undo_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
1381 undo_list = current->sysvsem.undo_list;
1382 if (!undo_list) {
Matt Helsley2453a302006-10-02 02:18:25 -07001383 undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 if (undo_list == NULL)
1385 return -ENOMEM;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +02001386 spin_lock_init(&undo_list->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 atomic_set(&undo_list->refcnt, 1);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001388 INIT_LIST_HEAD(&undo_list->list_proc);
1389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 current->sysvsem.undo_list = undo_list;
1391 }
1392 *undo_listp = undo_list;
1393 return 0;
1394}
1395
Nick Pigginbf17bb72009-12-15 16:47:28 -08001396static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397{
Nick Pigginbf17bb72009-12-15 16:47:28 -08001398 struct sem_undo *un;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Nick Pigginbf17bb72009-12-15 16:47:28 -08001400 list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
1401 if (un->semid == semid)
1402 return un;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001404 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405}
1406
Nick Pigginbf17bb72009-12-15 16:47:28 -08001407static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1408{
1409 struct sem_undo *un;
1410
1411 assert_spin_locked(&ulp->lock);
1412
1413 un = __lookup_undo(ulp, semid);
1414 if (un) {
1415 list_del_rcu(&un->list_proc);
1416 list_add_rcu(&un->list_proc, &ulp->list_proc);
1417 }
1418 return un;
1419}
1420
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001421/**
1422 * find_alloc_undo - Lookup (and if not present create) undo array
1423 * @ns: namespace
1424 * @semid: semaphore array id
1425 *
1426 * The function looks up (and if not present creates) the undo structure.
1427 * The size of the undo structure depends on the size of the semaphore
1428 * array, thus the alloc path is not that straightforward.
Manfred Spraul380af1b2008-07-25 01:48:06 -07001429 * Lifetime-rules: sem_undo is rcu-protected, on success, the function
1430 * performs a rcu_read_lock().
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001431 */
1432static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433{
1434 struct sem_array *sma;
1435 struct sem_undo_list *ulp;
1436 struct sem_undo *un, *new;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001437 int nsems, error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438
1439 error = get_undo_list(&ulp);
1440 if (error)
1441 return ERR_PTR(error);
1442
Manfred Spraul380af1b2008-07-25 01:48:06 -07001443 rcu_read_lock();
Pierre Peifferc530c6a2007-10-18 23:40:55 -07001444 spin_lock(&ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 un = lookup_undo(ulp, semid);
Pierre Peifferc530c6a2007-10-18 23:40:55 -07001446 spin_unlock(&ulp->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 if (likely(un!=NULL))
1448 goto out;
1449
1450 /* no undo structure around - allocate one. */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001451 /* step 1: figure out the size of the semaphore array */
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001452 sma = sem_obtain_object_check(ns, semid);
1453 if (IS_ERR(sma)) {
1454 rcu_read_unlock();
Julia Lawall4de85cd2010-05-26 14:43:44 -07001455 return ERR_CAST(sma);
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001456 }
Nadia Derbey023a5352007-10-18 23:40:51 -07001457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 nsems = sma->sem_nsems;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001459 if (!ipc_rcu_getref(sma)) {
1460 rcu_read_unlock();
1461 un = ERR_PTR(-EIDRM);
1462 goto out;
1463 }
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001464 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001466 /* step 2: allocate new undo structure */
Burman Yan4668edc2006-12-06 20:38:51 -08001467 new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 if (!new) {
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001469 sem_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 return ERR_PTR(-ENOMEM);
1471 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472
Manfred Spraul380af1b2008-07-25 01:48:06 -07001473 /* step 3: Acquire the lock on semaphore array */
Linus Torvalds4091fd92013-05-04 10:13:40 -07001474 rcu_read_lock();
Pierre Peiffer6ff37972008-04-29 01:00:46 -07001475 sem_lock_and_putref(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476 if (sma->sem_perm.deleted) {
Rik van Riel6062a8d2013-04-30 19:15:44 -07001477 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001478 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 kfree(new);
1480 un = ERR_PTR(-EIDRM);
1481 goto out;
1482 }
Manfred Spraul380af1b2008-07-25 01:48:06 -07001483 spin_lock(&ulp->lock);
1484
1485 /*
1486 * step 4: check for races: did someone else allocate the undo struct?
1487 */
1488 un = lookup_undo(ulp, semid);
1489 if (un) {
1490 kfree(new);
1491 goto success;
1492 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001493 /* step 5: initialize & link new undo structure */
1494 new->semadj = (short *) &new[1];
Manfred Spraul380af1b2008-07-25 01:48:06 -07001495 new->ulp = ulp;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001496 new->semid = semid;
1497 assert_spin_locked(&ulp->lock);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001498 list_add_rcu(&new->list_proc, &ulp->list_proc);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001499 assert_spin_locked(&sma->sem_perm.lock);
1500 list_add(&new->list_id, &sma->list_id);
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001501 un = new;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001502
1503success:
1504 spin_unlock(&ulp->lock);
Rik van Riel6062a8d2013-04-30 19:15:44 -07001505 sem_unlock(sma, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506out:
1507 return un;
1508}
1509
Manfred Spraulc61284e2010-07-20 13:24:23 -07001510
1511/**
1512 * get_queue_result - Retrieve the result code from sem_queue
1513 * @q: Pointer to queue structure
1514 *
1515 * Retrieve the return code from the pending queue. If IN_WAKEUP is found in
1516 * q->status, then we must loop until the value is replaced with the final
1517 * value: This may happen if a task is woken up by an unrelated event (e.g.
1518 * signal) and in parallel the task is woken up by another task because it got
1519 * the requested semaphores.
1520 *
1521 * The function can be called with or without holding the semaphore spinlock.
1522 */
1523static int get_queue_result(struct sem_queue *q)
1524{
1525 int error;
1526
1527 error = q->status;
1528 while (unlikely(error == IN_WAKEUP)) {
1529 cpu_relax();
1530 error = q->status;
1531 }
1532
1533 return error;
1534}
1535
1536
Heiko Carstensd5460c92009-01-14 14:14:27 +01001537SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
1538 unsigned, nsops, const struct timespec __user *, timeout)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539{
1540 int error = -EINVAL;
1541 struct sem_array *sma;
1542 struct sembuf fast_sops[SEMOPM_FAST];
1543 struct sembuf* sops = fast_sops, *sop;
1544 struct sem_undo *un;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001545 int undos = 0, alter = 0, max, locknum;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 struct sem_queue queue;
1547 unsigned long jiffies_left = 0;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001548 struct ipc_namespace *ns;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001549 struct list_head tasks;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001550
1551 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552
1553 if (nsops < 1 || semid < 0)
1554 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001555 if (nsops > ns->sc_semopm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 return -E2BIG;
1557 if(nsops > SEMOPM_FAST) {
1558 sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
1559 if(sops==NULL)
1560 return -ENOMEM;
1561 }
1562 if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1563 error=-EFAULT;
1564 goto out_free;
1565 }
1566 if (timeout) {
1567 struct timespec _timeout;
1568 if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1569 error = -EFAULT;
1570 goto out_free;
1571 }
1572 if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1573 _timeout.tv_nsec >= 1000000000L) {
1574 error = -EINVAL;
1575 goto out_free;
1576 }
1577 jiffies_left = timespec_to_jiffies(&_timeout);
1578 }
1579 max = 0;
1580 for (sop = sops; sop < sops + nsops; sop++) {
1581 if (sop->sem_num >= max)
1582 max = sop->sem_num;
1583 if (sop->sem_flg & SEM_UNDO)
Manfred Spraulb78755a2005-06-23 00:10:06 -07001584 undos = 1;
1585 if (sop->sem_op != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 alter = 1;
1587 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588
Rik van Riel6062a8d2013-04-30 19:15:44 -07001589 INIT_LIST_HEAD(&tasks);
1590
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 if (undos) {
Rik van Riel6062a8d2013-04-30 19:15:44 -07001592 /* On success, find_alloc_undo takes the rcu_read_lock */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001593 un = find_alloc_undo(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 if (IS_ERR(un)) {
1595 error = PTR_ERR(un);
1596 goto out_free;
1597 }
Rik van Riel6062a8d2013-04-30 19:15:44 -07001598 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 un = NULL;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001600 rcu_read_lock();
1601 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001603 sma = sem_obtain_object_check(ns, semid);
Nadia Derbey023a5352007-10-18 23:40:51 -07001604 if (IS_ERR(sma)) {
Rik van Riel6062a8d2013-04-30 19:15:44 -07001605 rcu_read_unlock();
Nadia Derbey023a5352007-10-18 23:40:51 -07001606 error = PTR_ERR(sma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 goto out_free;
Nadia Derbey023a5352007-10-18 23:40:51 -07001608 }
1609
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001610 error = -EFBIG;
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001611 if (max >= sma->sem_nsems)
1612 goto out_rcu_wakeup;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001613
1614 error = -EACCES;
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001615 if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1616 goto out_rcu_wakeup;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001617
1618 error = security_sem_semop(sma, sops, nsops, alter);
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001619 if (error)
1620 goto out_rcu_wakeup;
Davidlohr Bueso16df3672013-04-30 19:15:29 -07001621
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622 /*
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001623 * semid identifiers are not unique - find_alloc_undo may have
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 * allocated an undo structure, it was invalidated by an RMID
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001625 * and now a new array with received the same id. Check and fail.
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001626 * This case can be detected checking un->semid. The existence of
Manfred Spraul380af1b2008-07-25 01:48:06 -07001627 * "un" itself is guaranteed by rcu.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001629 error = -EIDRM;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001630 locknum = sem_lock(sma, sops, nsops);
1631 if (un && un->semid == -1)
1632 goto out_unlock_free;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001633
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001634 error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 if (error <= 0) {
1636 if (alter && error == 0)
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001637 do_smart_update(sma, sops, nsops, 1, &tasks);
Manfred Spraul636c6be2009-12-15 16:47:33 -08001638
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639 goto out_unlock_free;
1640 }
1641
1642 /* We need to sleep on this operation, so we put the current
1643 * task into the pending queue and go to sleep.
1644 */
1645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 queue.sops = sops;
1647 queue.nsops = nsops;
1648 queue.undo = un;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001649 queue.pid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 queue.alter = alter;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
Manfred Spraulb97e8202009-12-15 16:47:32 -08001652 if (nsops == 1) {
1653 struct sem *curr;
1654 curr = &sma->sem_base[sops->sem_num];
1655
1656 if (alter)
Rik van Riel9f1bc2c92013-04-30 19:15:39 -07001657 list_add_tail(&queue.list, &curr->sem_pending);
Manfred Spraulb97e8202009-12-15 16:47:32 -08001658 else
Rik van Riel9f1bc2c92013-04-30 19:15:39 -07001659 list_add(&queue.list, &curr->sem_pending);
Manfred Spraulb97e8202009-12-15 16:47:32 -08001660 } else {
Rik van Riel9f1bc2c92013-04-30 19:15:39 -07001661 if (alter)
1662 list_add_tail(&queue.list, &sma->sem_pending);
1663 else
1664 list_add(&queue.list, &sma->sem_pending);
Manfred Spraulb97e8202009-12-15 16:47:32 -08001665 sma->complex_count++;
1666 }
1667
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 queue.status = -EINTR;
1669 queue.sleeper = current;
Manfred Spraul0b0577f2011-11-02 13:38:52 -07001670
1671sleep_again:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 current->state = TASK_INTERRUPTIBLE;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001673 sem_unlock(sma, locknum);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001674 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675
1676 if (timeout)
1677 jiffies_left = schedule_timeout(jiffies_left);
1678 else
1679 schedule();
1680
Manfred Spraulc61284e2010-07-20 13:24:23 -07001681 error = get_queue_result(&queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682
1683 if (error != -EINTR) {
1684 /* fast path: update_queue already obtained all requested
Manfred Spraulc61284e2010-07-20 13:24:23 -07001685 * resources.
1686 * Perform a smp_mb(): User space could assume that semop()
1687 * is a memory barrier: Without the mb(), the cpu could
1688 * speculatively read in user space stale data that was
1689 * overwritten by the previous owner of the semaphore.
1690 */
1691 smp_mb();
1692
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 goto out_free;
1694 }
1695
Linus Torvalds321310c2013-05-04 10:47:57 -07001696 rcu_read_lock();
Rik van Riel6062a8d2013-04-30 19:15:44 -07001697 sma = sem_obtain_lock(ns, semid, sops, nsops, &locknum);
Manfred Sprauld694ad62011-07-25 17:11:47 -07001698
1699 /*
1700 * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing.
1701 */
1702 error = get_queue_result(&queue);
1703
1704 /*
1705 * Array removed? If yes, leave without sem_unlock().
1706 */
Nadia Derbey023a5352007-10-18 23:40:51 -07001707 if (IS_ERR(sma)) {
Linus Torvalds321310c2013-05-04 10:47:57 -07001708 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 goto out_free;
1710 }
1711
Manfred Spraulc61284e2010-07-20 13:24:23 -07001712
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 /*
Manfred Sprauld694ad62011-07-25 17:11:47 -07001714 * If queue.status != -EINTR we are woken up by another process.
1715 * Leave without unlink_queue(), but with sem_unlock().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 */
Manfred Spraulc61284e2010-07-20 13:24:23 -07001717
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718 if (error != -EINTR) {
1719 goto out_unlock_free;
1720 }
1721
1722 /*
1723 * If an interrupt occurred we have to clean up the queue
1724 */
1725 if (timeout && jiffies_left == 0)
1726 error = -EAGAIN;
Manfred Spraul0b0577f2011-11-02 13:38:52 -07001727
1728 /*
1729 * If the wakeup was spurious, just retry
1730 */
1731 if (error == -EINTR && !signal_pending(current))
1732 goto sleep_again;
1733
Manfred Spraulb97e8202009-12-15 16:47:32 -08001734 unlink_queue(sma, &queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735
1736out_unlock_free:
Rik van Riel6062a8d2013-04-30 19:15:44 -07001737 sem_unlock(sma, locknum);
Linus Torvaldsc728b9c2013-05-04 11:04:29 -07001738out_rcu_wakeup:
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001739 rcu_read_unlock();
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001740 wake_up_sem_queue_do(&tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741out_free:
1742 if(sops != fast_sops)
1743 kfree(sops);
1744 return error;
1745}
1746
Heiko Carstensd5460c92009-01-14 14:14:27 +01001747SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
1748 unsigned, nsops)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749{
1750 return sys_semtimedop(semid, tsops, nsops, NULL);
1751}
1752
1753/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1754 * parent and child tasks.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 */
1756
1757int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1758{
1759 struct sem_undo_list *undo_list;
1760 int error;
1761
1762 if (clone_flags & CLONE_SYSVSEM) {
1763 error = get_undo_list(&undo_list);
1764 if (error)
1765 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 atomic_inc(&undo_list->refcnt);
1767 tsk->sysvsem.undo_list = undo_list;
1768 } else
1769 tsk->sysvsem.undo_list = NULL;
1770
1771 return 0;
1772}
1773
1774/*
1775 * add semadj values to semaphores, free undo structures.
1776 * undo structures are not freed when semaphore arrays are destroyed
1777 * so some of them may be out of date.
1778 * IMPLEMENTATION NOTE: There is some confusion over whether the
1779 * set of adjustments that needs to be done should be done in an atomic
1780 * manner or not. That is, if we are attempting to decrement the semval
1781 * should we queue up and wait until we can do so legally?
1782 * The original implementation attempted to do this (queue and wait).
1783 * The current implementation does not do so. The POSIX standard
1784 * and SVID should be consulted to determine what behavior is mandated.
1785 */
1786void exit_sem(struct task_struct *tsk)
1787{
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001788 struct sem_undo_list *ulp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001790 ulp = tsk->sysvsem.undo_list;
1791 if (!ulp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 return;
Manfred Spraul9edff4a2008-04-29 01:00:57 -07001793 tsk->sysvsem.undo_list = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001795 if (!atomic_dec_and_test(&ulp->refcnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 return;
1797
Manfred Spraul380af1b2008-07-25 01:48:06 -07001798 for (;;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799 struct sem_array *sma;
Manfred Spraul380af1b2008-07-25 01:48:06 -07001800 struct sem_undo *un;
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001801 struct list_head tasks;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001802 int semid, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803
Manfred Spraul380af1b2008-07-25 01:48:06 -07001804 rcu_read_lock();
Jiri Pirko05725f72009-04-14 20:17:16 +02001805 un = list_entry_rcu(ulp->list_proc.next,
1806 struct sem_undo, list_proc);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001807 if (&un->list_proc == &ulp->list_proc)
1808 semid = -1;
1809 else
1810 semid = un->semid;
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001811
Rik van Riel6062a8d2013-04-30 19:15:44 -07001812 if (semid == -1) {
1813 rcu_read_unlock();
Manfred Spraul380af1b2008-07-25 01:48:06 -07001814 break;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001815 }
Manfred Spraul380af1b2008-07-25 01:48:06 -07001816
Rik van Riel6062a8d2013-04-30 19:15:44 -07001817 sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, un->semid);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001818 /* exit_sem raced with IPC_RMID, nothing to do */
Rik van Riel6062a8d2013-04-30 19:15:44 -07001819 if (IS_ERR(sma)) {
1820 rcu_read_unlock();
Manfred Spraul380af1b2008-07-25 01:48:06 -07001821 continue;
Rik van Riel6062a8d2013-04-30 19:15:44 -07001822 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823
Rik van Riel6062a8d2013-04-30 19:15:44 -07001824 sem_lock(sma, NULL, -1);
Nick Pigginbf17bb72009-12-15 16:47:28 -08001825 un = __lookup_undo(ulp, semid);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001826 if (un == NULL) {
1827 /* exit_sem raced with IPC_RMID+semget() that created
1828 * exactly the same semid. Nothing to do.
1829 */
Rik van Riel6062a8d2013-04-30 19:15:44 -07001830 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001831 rcu_read_unlock();
Manfred Spraul380af1b2008-07-25 01:48:06 -07001832 continue;
1833 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834
Manfred Spraul380af1b2008-07-25 01:48:06 -07001835 /* remove un from the linked lists */
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001836 assert_spin_locked(&sma->sem_perm.lock);
1837 list_del(&un->list_id);
1838
Manfred Spraul380af1b2008-07-25 01:48:06 -07001839 spin_lock(&ulp->lock);
1840 list_del_rcu(&un->list_proc);
1841 spin_unlock(&ulp->lock);
1842
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001843 /* perform adjustments registered in un */
1844 for (i = 0; i < sma->sem_nsems; i++) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001845 struct sem * semaphore = &sma->sem_base[i];
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001846 if (un->semadj[i]) {
1847 semaphore->semval += un->semadj[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 /*
1849 * Range checks of the new semaphore value,
1850 * not defined by sus:
1851 * - Some unices ignore the undo entirely
1852 * (e.g. HP UX 11i 11.22, Tru64 V5.1)
1853 * - some cap the value (e.g. FreeBSD caps
1854 * at 0, but doesn't enforce SEMVMX)
1855 *
1856 * Linux caps the semaphore value, both at 0
1857 * and at SEMVMX.
1858 *
1859 * Manfred <manfred@colorfullife.com>
1860 */
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001861 if (semaphore->semval < 0)
1862 semaphore->semval = 0;
1863 if (semaphore->semval > SEMVMX)
1864 semaphore->semval = SEMVMX;
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001865 semaphore->sempid = task_tgid_vnr(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 }
1867 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868 /* maybe some queued-up processes were waiting for this */
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001869 INIT_LIST_HEAD(&tasks);
1870 do_smart_update(sma, NULL, 0, 1, &tasks);
Rik van Riel6062a8d2013-04-30 19:15:44 -07001871 sem_unlock(sma, -1);
Linus Torvalds6d49dab2013-05-03 15:04:40 -07001872 rcu_read_unlock();
Manfred Spraul0a2b9d42010-05-26 14:43:41 -07001873 wake_up_sem_queue_do(&tasks);
Manfred Spraul380af1b2008-07-25 01:48:06 -07001874
Lai Jiangshan693a8b62011-03-18 12:09:35 +08001875 kfree_rcu(un, rcu);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 }
Manfred Spraul4daa28f2008-07-25 01:48:04 -07001877 kfree(ulp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878}
1879
1880#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -07001881static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882{
Eric W. Biederman1efdb692012-02-07 16:54:11 -08001883 struct user_namespace *user_ns = seq_user_ns(s);
Mike Waychison19b49462005-09-06 15:17:10 -07001884 struct sem_array *sma = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885
Mike Waychison19b49462005-09-06 15:17:10 -07001886 return seq_printf(s,
Manfred Spraulb97e8202009-12-15 16:47:32 -08001887 "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
Mike Waychison19b49462005-09-06 15:17:10 -07001888 sma->sem_perm.key,
Nadia Derbey7ca7e562007-10-18 23:40:48 -07001889 sma->sem_perm.id,
Mike Waychison19b49462005-09-06 15:17:10 -07001890 sma->sem_perm.mode,
1891 sma->sem_nsems,
Eric W. Biederman1efdb692012-02-07 16:54:11 -08001892 from_kuid_munged(user_ns, sma->sem_perm.uid),
1893 from_kgid_munged(user_ns, sma->sem_perm.gid),
1894 from_kuid_munged(user_ns, sma->sem_perm.cuid),
1895 from_kgid_munged(user_ns, sma->sem_perm.cgid),
Mike Waychison19b49462005-09-06 15:17:10 -07001896 sma->sem_otime,
1897 sma->sem_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898}
1899#endif