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1	/*
2	* linux/ipc/sem.c
3	* Copyright (C) 1992 Krishna Balasubramanian
4	* Copyright (C) 1995 Eric Schenk, Bruno Haible
5	*
6	* /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
7	*
8	* SMP-threaded, sysctl's added
9	* (c) 1999 Manfred Spraul <manfred@colorfullife.com>
10	* Enforced range limit on SEM_UNDO
11	* (c) 2001 Red Hat Inc
12	* Lockless wakeup
13	* (c) 2003 Manfred Spraul <manfred@colorfullife.com>
14	* Further wakeup optimizations, documentation
15	* (c) 2010 Manfred Spraul <manfred@colorfullife.com>
16	*
17	* support for audit of ipc object properties and permission changes
18	* Dustin Kirkland <dustin.kirkland@us.ibm.com>
19	*
20	* namespaces support
21	* OpenVZ, SWsoft Inc.
22	* Pavel Emelianov <xemul@openvz.org>
23	*
24	* Implementation notes: (May 2010)
25	* This file implements System V semaphores.
26	*
27	* User space visible behavior:
28	* - FIFO ordering for semop() operations (just FIFO, not starvation
29	* protection)
30	* - multiple semaphore operations that alter the same semaphore in
31	* one semop() are handled.
32	* - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and
33	* SETALL calls.
34	* - two Linux specific semctl() commands: SEM_STAT, SEM_INFO.
35	* - undo adjustments at process exit are limited to 0..SEMVMX.
36	* - namespace are supported.
37	* - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing
38	* to /proc/sys/kernel/sem.
39	* - statistics about the usage are reported in /proc/sysvipc/sem.
40	*
41	* Internals:
42	* - scalability:
43	* - all global variables are read-mostly.
44	* - semop() calls and semctl(RMID) are synchronized by RCU.
45	* - most operations do write operations (actually: spin_lock calls) to
46	* the per-semaphore array structure.
47	* Thus: Perfect SMP scaling between independent semaphore arrays.
48	* If multiple semaphores in one array are used, then cache line
49	* trashing on the semaphore array spinlock will limit the scaling.
50	* - semncnt and semzcnt are calculated on demand in count_semncnt() and
51	* count_semzcnt()
52	* - the task that performs a successful semop() scans the list of all
53	* sleeping tasks and completes any pending operations that can be fulfilled.
54	* Semaphores are actively given to waiting tasks (necessary for FIFO).
55	* (see update_queue())
56	* - To improve the scalability, the actual wake-up calls are performed after
57	* dropping all locks. (see wake_up_sem_queue_prepare(),
58	* wake_up_sem_queue_do())
59	* - All work is done by the waker, the woken up task does not have to do
60	* anything - not even acquiring a lock or dropping a refcount.
61	* - A woken up task may not even touch the semaphore array anymore, it may
62	* have been destroyed already by a semctl(RMID).
63	* - The synchronizations between wake-ups due to a timeout/signal and a
64	* wake-up due to a completed semaphore operation is achieved by using an
65	* intermediate state (IN_WAKEUP).
66	* - UNDO values are stored in an array (one per process and per
67	* semaphore array, lazily allocated). For backwards compatibility, multiple
68	* modes for the UNDO variables are supported (per process, per thread)
69	* (see copy_semundo, CLONE_SYSVSEM)
70	* - There are two lists of the pending operations: a per-array list
71	* and per-semaphore list (stored in the array). This allows to achieve FIFO
72	* ordering without always scanning all pending operations.
73	* The worst-case behavior is nevertheless O(N^2) for N wakeups.
74	*/
75
76	#include <linux/slab.h>
77	#include <linux/spinlock.h>
78	#include <linux/init.h>
79	#include <linux/proc_fs.h>
80	#include <linux/time.h>
81	#include <linux/security.h>
82	#include <linux/syscalls.h>
83	#include <linux/audit.h>
84	#include <linux/capability.h>
85	#include <linux/seq_file.h>
86	#include <linux/rwsem.h>
87	#include <linux/nsproxy.h>
88	#include <linux/ipc_namespace.h>
89
90	#include <asm/uaccess.h>
91	#include "util.h"
92
93	#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
94
95	#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
96	#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)
97
98	static int newary(struct ipc_namespace , struct ipc_params );
99	static void freeary(struct ipc_namespace , struct kern_ipc_perm );
100	#ifdef CONFIG_PROC_FS
101	static int sysvipc_sem_proc_show(struct seq_file s, void it);
102	#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
116	#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]
120
121	void sem_init_ns(struct ipc_namespace *ns)
122	{
123	ns->sc_semmsl = SEMMSL;
124	ns->sc_semmns = SEMMNS;
125	ns->sc_semopm = SEMOPM;
126	ns->sc_semmni = SEMMNI;
127	ns->used_sems = 0;
128	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
129	}
130
131	#ifdef CONFIG_IPC_NS
132	void sem_exit_ns(struct ipc_namespace *ns)
133	{
134	free_ipcs(ns, &sem_ids(ns), freeary);
135	idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
136	}
137	#endif
138
139	void __init sem_init (void)
140	{
141	sem_init_ns(&init_ipc_ns);
142	ipc_init_proc_interface("sysvipc/sem",
143	" key semid perms nsems uid gid cuid cgid otime ctime\n",
144	IPC_SEM_IDS, sysvipc_sem_proc_show);
145	}
146
147	/*
148	* sem_lock_(check_) routines are called in the paths where the rw_mutex
149	* is not held.
150	*/
151	static inline struct sem_array sem_lock(struct ipc_namespace ns, int id)
152	{
153	struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
154
155	if (IS_ERR(ipcp))
156	return (struct sem_array *)ipcp;
157
158	return container_of(ipcp, struct sem_array, sem_perm);
159	}
160
161	static inline struct sem_array sem_lock_check(struct ipc_namespace ns,
162	int id)
163	{
164	struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id);
165
166	if (IS_ERR(ipcp))
167	return (struct sem_array *)ipcp;
168
169	return container_of(ipcp, struct sem_array, sem_perm);
170	}
171
172	static 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
178	static inline void sem_getref_and_unlock(struct sem_array *sma)
179	{
180	ipc_rcu_getref(sma);
181	ipc_unlock(&(sma)->sem_perm);
182	}
183
184	static 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
191	static inline void sem_rmid(struct ipc_namespace ns, struct sem_array s)
192	{
193	ipc_rmid(&sem_ids(ns), &s->sem_perm);
194	}
195
196	/*
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
211	* performing any operation on the sem array.
212	* * 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
230	/**
231	* newary - Create a new semaphore set
232	* @ns: namespace
233	* @params: ptr to the structure that contains key, semflg and nsems
234	*
235	* Called with sem_ids.rw_mutex held (as a writer)
236	*/
237
238	static int newary(struct ipc_namespace ns, struct ipc_params params)
239	{
240	int id;
241	int retval;
242	struct sem_array *sma;
243	int size;
244	key_t key = params->key;
245	int nsems = params->u.nsems;
246	int semflg = params->flg;
247	int i;
248
249	if (!nsems)
250	return -EINVAL;
251	if (ns->used_sems + nsems > ns->sc_semmns)
252	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
271	id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
272	if (id < 0) {
273	security_sem_free(sma);
274	ipc_rcu_putref(sma);
275	return id;
276	}
277	ns->used_sems += nsems;
278
279	sma->sem_base = (struct sem *) &sma[1];
280
281	for (i = 0; i < nsems; i++)
282	INIT_LIST_HEAD(&sma->sem_base[i].sem_pending);
283
284	sma->complex_count = 0;
285	INIT_LIST_HEAD(&sma->sem_pending);
286	INIT_LIST_HEAD(&sma->list_id);
287	sma->sem_nsems = nsems;
288	sma->sem_ctime = get_seconds();
289	sem_unlock(sma);
290
291	return sma->sem_perm.id;
292	}
293
294
295	/*
296	* Called with sem_ids.rw_mutex and ipcp locked.
297	*/
298	static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
299	{
300	struct sem_array *sma;
301
302	sma = container_of(ipcp, struct sem_array, sem_perm);
303	return security_sem_associate(sma, semflg);
304	}
305
306	/*
307	* Called with sem_ids.rw_mutex and ipcp locked.
308	*/
309	static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
310	struct ipc_params *params)
311	{
312	struct sem_array *sma;
313
314	sma = container_of(ipcp, struct sem_array, sem_perm);
315	if (params->u.nsems > sma->sem_nsems)
316	return -EINVAL;
317
318	return 0;
319	}
320
321	SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
322	{
323	struct ipc_namespace *ns;
324	struct ipc_ops sem_ops;
325	struct ipc_params sem_params;
326
327	ns = current->nsproxy->ipc_ns;
328
329	if (nsems < 0 \|\| nsems > ns->sc_semmsl)
330	return -EINVAL;
331
332	sem_ops.getnew = newary;
333	sem_ops.associate = sem_security;
334	sem_ops.more_checks = sem_more_checks;
335
336	sem_params.key = key;
337	sem_params.flg = semflg;
338	sem_params.u.nsems = nsems;
339
340	return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
341	}
342
343	/*
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
348	static 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
387	return 0;
388
389	out_of_range:
390	result = -ERANGE;
391	goto undo;
392
393	would_block:
394	if (sop->sem_flg & IPC_NOWAIT)
395	result = -EAGAIN;
396	else
397	result = 1;
398
399	undo:
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
409	/** 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.
414	*/
415	static void wake_up_sem_queue_prepare(struct list_head *pt,
416	struct sem_queue *q, int error)
417	{
418	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	}
425	q->status = IN_WAKEUP;
426	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	*/
440	static 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();
454	}
455
456	static 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
465	/** 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	*/
474	static 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
528
529	/**
530	* update_queue(sma, semnum): Look for tasks that can be completed.
531	* @sma: semaphore array.
532	* @semnum: semaphore that was modified.
533	* @pt: list head for the tasks that must be woken up.
534	*
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.
538	* 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.
541	*/
542	static int update_queue(struct sem_array sma, int semnum, struct list_head pt)
543	{
544	struct sem_queue *q;
545	struct list_head *walk;
546	struct list_head *pending_list;
547	int offset;
548	int semop_completed = 0;
549
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	}
564
565	again:
566	walk = pending_list->next;
567	while (walk != pending_list) {
568	int error, restart;
569
570	q = (struct sem_queue )((char )walk - offset);
571	walk = walk->next;
572
573	/* 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
584	error = try_atomic_semop(sma, q->sops, q->nsops,
585	q->undo, q->pid);
586
587	/* Does q->sleeper still need to sleep? */
588	if (error > 0)
589	continue;
590
591	unlink_queue(sma, q);
592
593	if (error) {
594	restart = 0;
595	} else {
596	semop_completed = 1;
597	restart = check_restart(sma, q);
598	}
599
600	wake_up_sem_queue_prepare(pt, q, error);
601	if (restart)
602	goto again;
603	}
604	return semop_completed;
605	}
606
607	/**
608	* do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue
609	* @sma: semaphore array
610	* @sops: operations that were performed
611	* @nsops: number of operations
612	* @otime: force setting otime
613	* @pt: list head of the tasks that must be woken up.
614	*
615	* do_smart_update() does the required called to update_queue, based on the
616	* actual changes that were performed on the semaphore array.
617	* 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.
620	*/
621	static void do_smart_update(struct sem_array sma, struct sembuf sops, int nsops,
622	int otime, struct list_head *pt)
623	{
624	int i;
625
626	if (sma->complex_count \|\| sops == NULL) {
627	if (update_queue(sma, -1, pt))
628	otime = 1;
629	goto done;
630	}
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))
636	if (update_queue(sma, sops[i].sem_num, pt))
637	otime = 1;
638	}
639	done:
640	if (otime)
641	sma->sem_otime = get_seconds();
642	}
643
644
645	/* 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	*/
654	static int count_semncnt (struct sem_array * sma, ushort semnum)
655	{
656	int semncnt;
657	struct sem_queue * q;
658
659	semncnt = 0;
660	list_for_each_entry(q, &sma->sem_pending, list) {
661	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	}
672
673	static int count_semzcnt (struct sem_array * sma, ushort semnum)
674	{
675	int semzcnt;
676	struct sem_queue * q;
677
678	semzcnt = 0;
679	list_for_each_entry(q, &sma->sem_pending, list) {
680	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
692	static void free_un(struct rcu_head *head)
693	{
694	struct sem_undo *un = container_of(head, struct sem_undo, rcu);
695	kfree(un);
696	}
697
698	/* 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.
701	*/
702	static void freeary(struct ipc_namespace ns, struct kern_ipc_perm ipcp)
703	{
704	struct sem_undo un, tu;
705	struct sem_queue q, tq;
706	struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
707	struct list_head tasks;
708
709	/* Free the existing undo structures for this semaphore set. */
710	assert_spin_locked(&sma->sem_perm.lock);
711	list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
712	list_del(&un->list_id);
713	spin_lock(&un->ulp->lock);
714	un->semid = -1;
715	list_del_rcu(&un->list_proc);
716	spin_unlock(&un->ulp->lock);
717	call_rcu(&un->rcu, free_un);
718	}
719
720	/* Wake up all pending processes and let them fail with EIDRM. */
721	INIT_LIST_HEAD(&tasks);
722	list_for_each_entry_safe(q, tq, &sma->sem_pending, list) {
723	unlink_queue(sma, q);
724	wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
725	}
726
727	/* Remove the semaphore set from the IDR */
728	sem_rmid(ns, sma);
729	sem_unlock(sma);
730
731	wake_up_sem_queue_do(&tasks);
732	ns->used_sems -= sma->sem_nsems;
733	security_sem_free(sma);
734	ipc_rcu_putref(sma);
735	}
736
737	static 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
746	memset(&out, 0, sizeof(out));
747
748	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
761	static int semctl_nolock(struct ipc_namespace *ns, int semid,
762	int cmd, int version, union semun arg)
763	{
764	int err;
765	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));
779	seminfo.semmni = ns->sc_semmni;
780	seminfo.semmns = ns->sc_semmns;
781	seminfo.semmsl = ns->sc_semmsl;
782	seminfo.semopm = ns->sc_semopm;
783	seminfo.semvmx = SEMVMX;
784	seminfo.semmnu = SEMMNU;
785	seminfo.semmap = SEMMAP;
786	seminfo.semume = SEMUME;
787	down_read(&sem_ids(ns).rw_mutex);
788	if (cmd == SEM_INFO) {
789	seminfo.semusz = sem_ids(ns).in_use;
790	seminfo.semaem = ns->used_sems;
791	} else {
792	seminfo.semusz = SEMUSZ;
793	seminfo.semaem = SEMAEM;
794	}
795	max_id = ipc_get_maxid(&sem_ids(ns));
796	up_read(&sem_ids(ns).rw_mutex);
797	if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
798	return -EFAULT;
799	return (max_id < 0) ? 0: max_id;
800	}
801	case IPC_STAT:
802	case SEM_STAT:
803	{
804	struct semid64_ds tbuf;
805	int id;
806
807	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	}
818
819	err = -EACCES;
820	if (ipcperms (&sma->sem_perm, S_IRUGO))
821	goto out_unlock;
822
823	err = security_sem_semctl(sma, cmd);
824	if (err)
825	goto out_unlock;
826
827	memset(&tbuf, 0, sizeof(tbuf));
828
829	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	}
841	out_unlock:
842	sem_unlock(sma);
843	return err;
844	}
845
846	static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
847	int cmd, int version, union semun arg)
848	{
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;
855	struct list_head tasks;
856
857	sma = sem_lock_check(ns, semid);
858	if (IS_ERR(sma))
859	return PTR_ERR(sma);
860
861	INIT_LIST_HEAD(&tasks);
862	nsems = sma->sem_nsems;
863
864	err = -EACCES;
865	if (ipcperms (&sma->sem_perm, (cmd==SETVAL\|\|cmd==SETALL)?S_IWUGO:S_IRUGO))
866	goto out_unlock;
867
868	err = security_sem_semctl(sma, cmd);
869	if (err)
870	goto out_unlock;
871
872	err = -EACCES;
873	switch (cmd) {
874	case GETALL:
875	{
876	ushort __user *array = arg.array;
877	int i;
878
879	if(nsems > SEMMSL_FAST) {
880	sem_getref_and_unlock(sma);
881
882	sem_io = ipc_alloc(sizeof(ushort)*nsems);
883	if(sem_io == NULL) {
884	sem_putref(sma);
885	return -ENOMEM;
886	}
887
888	sem_lock_and_putref(sma);
889	if (sma->sem_perm.deleted) {
890	sem_unlock(sma);
891	err = -EIDRM;
892	goto out_free;
893	}
894	}
895
896	for (i = 0; i < sma->sem_nsems; i++)
897	sem_io[i] = sma->sem_base[i].semval;
898	sem_unlock(sma);
899	err = 0;
900	if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
901	err = -EFAULT;
902	goto out_free;
903	}
904	case SETALL:
905	{
906	int i;
907	struct sem_undo *un;
908
909	sem_getref_and_unlock(sma);
910
911	if(nsems > SEMMSL_FAST) {
912	sem_io = ipc_alloc(sizeof(ushort)*nsems);
913	if(sem_io == NULL) {
914	sem_putref(sma);
915	return -ENOMEM;
916	}
917	}
918
919	if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
920	sem_putref(sma);
921	err = -EFAULT;
922	goto out_free;
923	}
924
925	for (i = 0; i < nsems; i++) {
926	if (sem_io[i] > SEMVMX) {
927	sem_putref(sma);
928	err = -ERANGE;
929	goto out_free;
930	}
931	}
932	sem_lock_and_putref(sma);
933	if (sma->sem_perm.deleted) {
934	sem_unlock(sma);
935	err = -EIDRM;
936	goto out_free;
937	}
938
939	for (i = 0; i < nsems; i++)
940	sma->sem_base[i].semval = sem_io[i];
941
942	assert_spin_locked(&sma->sem_perm.lock);
943	list_for_each_entry(un, &sma->list_id, list_id) {
944	for (i = 0; i < nsems; i++)
945	un->semadj[i] = 0;
946	}
947	sma->sem_ctime = get_seconds();
948	/* maybe some queued-up processes were waiting for this */
949	do_smart_update(sma, NULL, 0, 0, &tasks);
950	err = 0;
951	goto out_unlock;
952	}
953	/* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
954	}
955	err = -EINVAL;
956	if(semnum < 0 \|\| semnum >= nsems)
957	goto out_unlock;
958
959	curr = &sma->sem_base[semnum];
960
961	switch (cmd) {
962	case GETVAL:
963	err = curr->semval;
964	goto out_unlock;
965	case GETPID:
966	err = curr->sempid;
967	goto out_unlock;
968	case GETNCNT:
969	err = count_semncnt(sma,semnum);
970	goto out_unlock;
971	case GETZCNT:
972	err = count_semzcnt(sma,semnum);
973	goto out_unlock;
974	case SETVAL:
975	{
976	int val = arg.val;
977	struct sem_undo *un;
978
979	err = -ERANGE;
980	if (val > SEMVMX \|\| val < 0)
981	goto out_unlock;
982
983	assert_spin_locked(&sma->sem_perm.lock);
984	list_for_each_entry(un, &sma->list_id, list_id)
985	un->semadj[semnum] = 0;
986
987	curr->semval = val;
988	curr->sempid = task_tgid_vnr(current);
989	sma->sem_ctime = get_seconds();
990	/* maybe some queued-up processes were waiting for this */
991	do_smart_update(sma, NULL, 0, 0, &tasks);
992	err = 0;
993	goto out_unlock;
994	}
995	}
996	out_unlock:
997	sem_unlock(sma);
998	wake_up_sem_queue_do(&tasks);
999
1000	out_free:
1001	if(sem_io != fast_sem_io)
1002	ipc_free(sem_io, sizeof(ushort)*nsems);
1003	return err;
1004	}
1005
1006	static inline unsigned long
1007	copy_semid_from_user(struct semid64_ds out, void __user buf, int version)
1008	{
1009	switch(version) {
1010	case IPC_64:
1011	if (copy_from_user(out, buf, sizeof(*out)))
1012	return -EFAULT;
1013	return 0;
1014	case IPC_OLD:
1015	{
1016	struct semid_ds tbuf_old;
1017
1018	if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
1019	return -EFAULT;
1020
1021	out->sem_perm.uid = tbuf_old.sem_perm.uid;
1022	out->sem_perm.gid = tbuf_old.sem_perm.gid;
1023	out->sem_perm.mode = tbuf_old.sem_perm.mode;
1024
1025	return 0;
1026	}
1027	default:
1028	return -EINVAL;
1029	}
1030	}
1031
1032	/*
1033	* This function handles some semctl commands which require the rw_mutex
1034	* to be held in write mode.
1035	* NOTE: no locks must be held, the rw_mutex is taken inside this function.
1036	*/
1037	static int semctl_down(struct ipc_namespace *ns, int semid,
1038	int cmd, int version, union semun arg)
1039	{
1040	struct sem_array *sma;
1041	int err;
1042	struct semid64_ds semid64;
1043	struct kern_ipc_perm *ipcp;
1044
1045	if(cmd == IPC_SET) {
1046	if (copy_semid_from_user(&semid64, arg.buf, version))
1047	return -EFAULT;
1048	}
1049
1050	ipcp = ipcctl_pre_down(&sem_ids(ns), semid, cmd, &semid64.sem_perm, 0);
1051	if (IS_ERR(ipcp))
1052	return PTR_ERR(ipcp);
1053
1054	sma = container_of(ipcp, struct sem_array, sem_perm);
1055
1056	err = security_sem_semctl(sma, cmd);
1057	if (err)
1058	goto out_unlock;
1059
1060	switch(cmd){
1061	case IPC_RMID:
1062	freeary(ns, ipcp);
1063	goto out_up;
1064	case IPC_SET:
1065	ipc_update_perm(&semid64.sem_perm, ipcp);
1066	sma->sem_ctime = get_seconds();
1067	break;
1068	default:
1069	err = -EINVAL;
1070	}
1071
1072	out_unlock:
1073	sem_unlock(sma);
1074	out_up:
1075	up_write(&sem_ids(ns).rw_mutex);
1076	return err;
1077	}
1078
1079	SYSCALL_DEFINE(semctl)(int semid, int semnum, int cmd, union semun arg)
1080	{
1081	int err = -EINVAL;
1082	int version;
1083	struct ipc_namespace *ns;
1084
1085	if (semid < 0)
1086	return -EINVAL;
1087
1088	version = ipc_parse_version(&cmd);
1089	ns = current->nsproxy->ipc_ns;
1090
1091	switch(cmd) {
1092	case IPC_INFO:
1093	case SEM_INFO:
1094	case IPC_STAT:
1095	case SEM_STAT:
1096	err = semctl_nolock(ns, semid, cmd, version, arg);
1097	return err;
1098	case GETALL:
1099	case GETVAL:
1100	case GETPID:
1101	case GETNCNT:
1102	case GETZCNT:
1103	case SETVAL:
1104	case SETALL:
1105	err = semctl_main(ns,semid,semnum,cmd,version,arg);
1106	return err;
1107	case IPC_RMID:
1108	case IPC_SET:
1109	err = semctl_down(ns, semid, cmd, version, arg);
1110	return err;
1111	default:
1112	return -EINVAL;
1113	}
1114	}
1115	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1116	asmlinkage long SyS_semctl(int semid, int semnum, int cmd, union semun arg)
1117	{
1118	return SYSC_semctl((int) semid, (int) semnum, (int) cmd, arg);
1119	}
1120	SYSCALL_ALIAS(sys_semctl, SyS_semctl);
1121	#endif
1122
1123	/* If the task doesn't already have a undo_list, then allocate one
1124	* here. We guarantee there is only one thread using this undo list,
1125	* and current is THE ONE
1126	*
1127	* If this allocation and assignment succeeds, but later
1128	* portions of this code fail, there is no need to free the sem_undo_list.
1129	* Just let it stay associated with the task, and it'll be freed later
1130	* at exit time.
1131	*
1132	* This can block, so callers must hold no locks.
1133	*/
1134	static inline int get_undo_list(struct sem_undo_list **undo_listp)
1135	{
1136	struct sem_undo_list *undo_list;
1137
1138	undo_list = current->sysvsem.undo_list;
1139	if (!undo_list) {
1140	undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
1141	if (undo_list == NULL)
1142	return -ENOMEM;
1143	spin_lock_init(&undo_list->lock);
1144	atomic_set(&undo_list->refcnt, 1);
1145	INIT_LIST_HEAD(&undo_list->list_proc);
1146
1147	current->sysvsem.undo_list = undo_list;
1148	}
1149	*undo_listp = undo_list;
1150	return 0;
1151	}
1152
1153	static struct sem_undo __lookup_undo(struct sem_undo_list ulp, int semid)
1154	{
1155	struct sem_undo *un;
1156
1157	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
1158	if (un->semid == semid)
1159	return un;
1160	}
1161	return NULL;
1162	}
1163
1164	static struct sem_undo lookup_undo(struct sem_undo_list ulp, int semid)
1165	{
1166	struct sem_undo *un;
1167
1168	assert_spin_locked(&ulp->lock);
1169
1170	un = __lookup_undo(ulp, semid);
1171	if (un) {
1172	list_del_rcu(&un->list_proc);
1173	list_add_rcu(&un->list_proc, &ulp->list_proc);
1174	}
1175	return un;
1176	}
1177
1178	/**
1179	* find_alloc_undo - Lookup (and if not present create) undo array
1180	* @ns: namespace
1181	* @semid: semaphore array id
1182	*
1183	* The function looks up (and if not present creates) the undo structure.
1184	* The size of the undo structure depends on the size of the semaphore
1185	* array, thus the alloc path is not that straightforward.
1186	* Lifetime-rules: sem_undo is rcu-protected, on success, the function
1187	* performs a rcu_read_lock().
1188	*/
1189	static struct sem_undo find_alloc_undo(struct ipc_namespace ns, int semid)
1190	{
1191	struct sem_array *sma;
1192	struct sem_undo_list *ulp;
1193	struct sem_undo un, new;
1194	int nsems;
1195	int error;
1196
1197	error = get_undo_list(&ulp);
1198	if (error)
1199	return ERR_PTR(error);
1200
1201	rcu_read_lock();
1202	spin_lock(&ulp->lock);
1203	un = lookup_undo(ulp, semid);
1204	spin_unlock(&ulp->lock);
1205	if (likely(un!=NULL))
1206	goto out;
1207	rcu_read_unlock();
1208
1209	/* no undo structure around - allocate one. */
1210	/* step 1: figure out the size of the semaphore array */
1211	sma = sem_lock_check(ns, semid);
1212	if (IS_ERR(sma))
1213	return ERR_CAST(sma);
1214
1215	nsems = sma->sem_nsems;
1216	sem_getref_and_unlock(sma);
1217
1218	/* step 2: allocate new undo structure */
1219	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
1220	if (!new) {
1221	sem_putref(sma);
1222	return ERR_PTR(-ENOMEM);
1223	}
1224
1225	/* step 3: Acquire the lock on semaphore array */
1226	sem_lock_and_putref(sma);
1227	if (sma->sem_perm.deleted) {
1228	sem_unlock(sma);
1229	kfree(new);
1230	un = ERR_PTR(-EIDRM);
1231	goto out;
1232	}
1233	spin_lock(&ulp->lock);
1234
1235	/*
1236	* step 4: check for races: did someone else allocate the undo struct?
1237	*/
1238	un = lookup_undo(ulp, semid);
1239	if (un) {
1240	kfree(new);
1241	goto success;
1242	}
1243	/* step 5: initialize & link new undo structure */
1244	new->semadj = (short *) &new[1];
1245	new->ulp = ulp;
1246	new->semid = semid;
1247	assert_spin_locked(&ulp->lock);
1248	list_add_rcu(&new->list_proc, &ulp->list_proc);
1249	assert_spin_locked(&sma->sem_perm.lock);
1250	list_add(&new->list_id, &sma->list_id);
1251	un = new;
1252
1253	success:
1254	spin_unlock(&ulp->lock);
1255	rcu_read_lock();
1256	sem_unlock(sma);
1257	out:
1258	return un;
1259	}
1260
1261
1262	/**
1263	* get_queue_result - Retrieve the result code from sem_queue
1264	* @q: Pointer to queue structure
1265	*
1266	* Retrieve the return code from the pending queue. If IN_WAKEUP is found in
1267	* q->status, then we must loop until the value is replaced with the final
1268	* value: This may happen if a task is woken up by an unrelated event (e.g.
1269	* signal) and in parallel the task is woken up by another task because it got
1270	* the requested semaphores.
1271	*
1272	* The function can be called with or without holding the semaphore spinlock.
1273	*/
1274	static int get_queue_result(struct sem_queue *q)
1275	{
1276	int error;
1277
1278	error = q->status;
1279	while (unlikely(error == IN_WAKEUP)) {
1280	cpu_relax();
1281	error = q->status;
1282	}
1283
1284	return error;
1285	}
1286
1287
1288	SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
1289	unsigned, nsops, const struct timespec __user *, timeout)
1290	{
1291	int error = -EINVAL;
1292	struct sem_array *sma;
1293	struct sembuf fast_sops[SEMOPM_FAST];
1294	struct sembuf* sops = fast_sops, *sop;
1295	struct sem_undo *un;
1296	int undos = 0, alter = 0, max;
1297	struct sem_queue queue;
1298	unsigned long jiffies_left = 0;
1299	struct ipc_namespace *ns;
1300	struct list_head tasks;
1301
1302	ns = current->nsproxy->ipc_ns;
1303
1304	if (nsops < 1 \|\| semid < 0)
1305	return -EINVAL;
1306	if (nsops > ns->sc_semopm)
1307	return -E2BIG;
1308	if(nsops > SEMOPM_FAST) {
1309	sops = kmalloc(sizeof(sops)nsops,GFP_KERNEL);
1310	if(sops==NULL)
1311	return -ENOMEM;
1312	}
1313	if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1314	error=-EFAULT;
1315	goto out_free;
1316	}
1317	if (timeout) {
1318	struct timespec _timeout;
1319	if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1320	error = -EFAULT;
1321	goto out_free;
1322	}
1323	if (_timeout.tv_sec < 0 \|\| _timeout.tv_nsec < 0 \|\|
1324	_timeout.tv_nsec >= 1000000000L) {
1325	error = -EINVAL;
1326	goto out_free;
1327	}
1328	jiffies_left = timespec_to_jiffies(&_timeout);
1329	}
1330	max = 0;
1331	for (sop = sops; sop < sops + nsops; sop++) {
1332	if (sop->sem_num >= max)
1333	max = sop->sem_num;
1334	if (sop->sem_flg & SEM_UNDO)
1335	undos = 1;
1336	if (sop->sem_op != 0)
1337	alter = 1;
1338	}
1339
1340	if (undos) {
1341	un = find_alloc_undo(ns, semid);
1342	if (IS_ERR(un)) {
1343	error = PTR_ERR(un);
1344	goto out_free;
1345	}
1346	} else
1347	un = NULL;
1348
1349	INIT_LIST_HEAD(&tasks);
1350
1351	sma = sem_lock_check(ns, semid);
1352	if (IS_ERR(sma)) {
1353	if (un)
1354	rcu_read_unlock();
1355	error = PTR_ERR(sma);
1356	goto out_free;
1357	}
1358
1359	/*
1360	* semid identifiers are not unique - find_alloc_undo may have
1361	* allocated an undo structure, it was invalidated by an RMID
1362	* and now a new array with received the same id. Check and fail.
1363	* This case can be detected checking un->semid. The existance of
1364	* "un" itself is guaranteed by rcu.
1365	*/
1366	error = -EIDRM;
1367	if (un) {
1368	if (un->semid == -1) {
1369	rcu_read_unlock();
1370	goto out_unlock_free;
1371	} else {
1372	/*
1373	* rcu lock can be released, "un" cannot disappear:
1374	* - sem_lock is acquired, thus IPC_RMID is
1375	* impossible.
1376	* - exit_sem is impossible, it always operates on
1377	* current (or a dead task).
1378	*/
1379
1380	rcu_read_unlock();
1381	}
1382	}
1383
1384	error = -EFBIG;
1385	if (max >= sma->sem_nsems)
1386	goto out_unlock_free;
1387
1388	error = -EACCES;
1389	if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1390	goto out_unlock_free;
1391
1392	error = security_sem_semop(sma, sops, nsops, alter);
1393	if (error)
1394	goto out_unlock_free;
1395
1396	error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
1397	if (error <= 0) {
1398	if (alter && error == 0)
1399	do_smart_update(sma, sops, nsops, 1, &tasks);
1400
1401	goto out_unlock_free;
1402	}
1403
1404	/* We need to sleep on this operation, so we put the current
1405	* task into the pending queue and go to sleep.
1406	*/
1407
1408	queue.sops = sops;
1409	queue.nsops = nsops;
1410	queue.undo = un;
1411	queue.pid = task_tgid_vnr(current);
1412	queue.alter = alter;
1413	if (alter)
1414	list_add_tail(&queue.list, &sma->sem_pending);
1415	else
1416	list_add(&queue.list, &sma->sem_pending);
1417
1418	if (nsops == 1) {
1419	struct sem *curr;
1420	curr = &sma->sem_base[sops->sem_num];
1421
1422	if (alter)
1423	list_add_tail(&queue.simple_list, &curr->sem_pending);
1424	else
1425	list_add(&queue.simple_list, &curr->sem_pending);
1426	} else {
1427	INIT_LIST_HEAD(&queue.simple_list);
1428	sma->complex_count++;
1429	}
1430
1431	queue.status = -EINTR;
1432	queue.sleeper = current;
1433	current->state = TASK_INTERRUPTIBLE;
1434	sem_unlock(sma);
1435
1436	if (timeout)
1437	jiffies_left = schedule_timeout(jiffies_left);
1438	else
1439	schedule();
1440
1441	error = get_queue_result(&queue);
1442
1443	if (error != -EINTR) {
1444	/* fast path: update_queue already obtained all requested
1445	* resources.
1446	* Perform a smp_mb(): User space could assume that semop()
1447	* is a memory barrier: Without the mb(), the cpu could
1448	* speculatively read in user space stale data that was
1449	* overwritten by the previous owner of the semaphore.
1450	*/
1451	smp_mb();
1452
1453	goto out_free;
1454	}
1455
1456	sma = sem_lock(ns, semid);
1457	if (IS_ERR(sma)) {
1458	error = -EIDRM;
1459	goto out_free;
1460	}
1461
1462	error = get_queue_result(&queue);
1463
1464	/*
1465	* If queue.status != -EINTR we are woken up by another process
1466	*/
1467
1468	if (error != -EINTR) {
1469	goto out_unlock_free;
1470	}
1471
1472	/*
1473	* If an interrupt occurred we have to clean up the queue
1474	*/
1475	if (timeout && jiffies_left == 0)
1476	error = -EAGAIN;
1477	unlink_queue(sma, &queue);
1478
1479	out_unlock_free:
1480	sem_unlock(sma);
1481
1482	wake_up_sem_queue_do(&tasks);
1483	out_free:
1484	if(sops != fast_sops)
1485	kfree(sops);
1486	return error;
1487	}
1488
1489	SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
1490	unsigned, nsops)
1491	{
1492	return sys_semtimedop(semid, tsops, nsops, NULL);
1493	}
1494
1495	/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1496	* parent and child tasks.
1497	*/
1498
1499	int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1500	{
1501	struct sem_undo_list *undo_list;
1502	int error;
1503
1504	if (clone_flags & CLONE_SYSVSEM) {
1505	error = get_undo_list(&undo_list);
1506	if (error)
1507	return error;
1508	atomic_inc(&undo_list->refcnt);
1509	tsk->sysvsem.undo_list = undo_list;
1510	} else
1511	tsk->sysvsem.undo_list = NULL;
1512
1513	return 0;
1514	}
1515
1516	/*
1517	* add semadj values to semaphores, free undo structures.
1518	* undo structures are not freed when semaphore arrays are destroyed
1519	* so some of them may be out of date.
1520	* IMPLEMENTATION NOTE: There is some confusion over whether the
1521	* set of adjustments that needs to be done should be done in an atomic
1522	* manner or not. That is, if we are attempting to decrement the semval
1523	* should we queue up and wait until we can do so legally?
1524	* The original implementation attempted to do this (queue and wait).
1525	* The current implementation does not do so. The POSIX standard
1526	* and SVID should be consulted to determine what behavior is mandated.
1527	*/
1528	void exit_sem(struct task_struct *tsk)
1529	{
1530	struct sem_undo_list *ulp;
1531
1532	ulp = tsk->sysvsem.undo_list;
1533	if (!ulp)
1534	return;
1535	tsk->sysvsem.undo_list = NULL;
1536
1537	if (!atomic_dec_and_test(&ulp->refcnt))
1538	return;
1539
1540	for (;;) {
1541	struct sem_array *sma;
1542	struct sem_undo *un;
1543	struct list_head tasks;
1544	int semid;
1545	int i;
1546
1547	rcu_read_lock();
1548	un = list_entry_rcu(ulp->list_proc.next,
1549	struct sem_undo, list_proc);
1550	if (&un->list_proc == &ulp->list_proc)
1551	semid = -1;
1552	else
1553	semid = un->semid;
1554	rcu_read_unlock();
1555
1556	if (semid == -1)
1557	break;
1558
1559	sma = sem_lock_check(tsk->nsproxy->ipc_ns, un->semid);
1560
1561	/* exit_sem raced with IPC_RMID, nothing to do */
1562	if (IS_ERR(sma))
1563	continue;
1564
1565	un = __lookup_undo(ulp, semid);
1566	if (un == NULL) {
1567	/* exit_sem raced with IPC_RMID+semget() that created
1568	* exactly the same semid. Nothing to do.
1569	*/
1570	sem_unlock(sma);
1571	continue;
1572	}
1573
1574	/* remove un from the linked lists */
1575	assert_spin_locked(&sma->sem_perm.lock);
1576	list_del(&un->list_id);
1577
1578	spin_lock(&ulp->lock);
1579	list_del_rcu(&un->list_proc);
1580	spin_unlock(&ulp->lock);
1581
1582	/* perform adjustments registered in un */
1583	for (i = 0; i < sma->sem_nsems; i++) {
1584	struct sem * semaphore = &sma->sem_base[i];
1585	if (un->semadj[i]) {
1586	semaphore->semval += un->semadj[i];
1587	/*
1588	* Range checks of the new semaphore value,
1589	* not defined by sus:
1590	* - Some unices ignore the undo entirely
1591	* (e.g. HP UX 11i 11.22, Tru64 V5.1)
1592	* - some cap the value (e.g. FreeBSD caps
1593	* at 0, but doesn't enforce SEMVMX)
1594	*
1595	* Linux caps the semaphore value, both at 0
1596	* and at SEMVMX.
1597	*
1598	* Manfred <manfred@colorfullife.com>
1599	*/
1600	if (semaphore->semval < 0)
1601	semaphore->semval = 0;
1602	if (semaphore->semval > SEMVMX)
1603	semaphore->semval = SEMVMX;
1604	semaphore->sempid = task_tgid_vnr(current);
1605	}
1606	}
1607	/* maybe some queued-up processes were waiting for this */
1608	INIT_LIST_HEAD(&tasks);
1609	do_smart_update(sma, NULL, 0, 1, &tasks);
1610	sem_unlock(sma);
1611	wake_up_sem_queue_do(&tasks);
1612
1613	call_rcu(&un->rcu, free_un);
1614	}
1615	kfree(ulp);
1616	}
1617
1618	#ifdef CONFIG_PROC_FS
1619	static int sysvipc_sem_proc_show(struct seq_file s, void it)
1620	{
1621	struct sem_array *sma = it;
1622
1623	return seq_printf(s,
1624	"%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
1625	sma->sem_perm.key,
1626	sma->sem_perm.id,
1627	sma->sem_perm.mode,
1628	sma->sem_nsems,
1629	sma->sem_perm.uid,
1630	sma->sem_perm.gid,
1631	sma->sem_perm.cuid,
1632	sma->sem_perm.cgid,
1633	sma->sem_otime,
1634	sma->sem_ctime);
1635	}
1636	#endif
1637

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