path: root/ipc/sem.c (plain)
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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_semcnt()
51	* - the task that performs a successful semop() scans the list of all
52	* sleeping tasks and completes any pending operations that can be fulfilled.
53	* Semaphores are actively given to waiting tasks (necessary for FIFO).
54	* (see update_queue())
55	* - To improve the scalability, the actual wake-up calls are performed after
56	* dropping all locks. (see wake_up_sem_queue_prepare(),
57	* wake_up_sem_queue_do())
58	* - All work is done by the waker, the woken up task does not have to do
59	* anything - not even acquiring a lock or dropping a refcount.
60	* - A woken up task may not even touch the semaphore array anymore, it may
61	* have been destroyed already by a semctl(RMID).
62	* - The synchronizations between wake-ups due to a timeout/signal and a
63	* wake-up due to a completed semaphore operation is achieved by using an
64	* intermediate state (IN_WAKEUP).
65	* - UNDO values are stored in an array (one per process and per
66	* semaphore array, lazily allocated). For backwards compatibility, multiple
67	* modes for the UNDO variables are supported (per process, per thread)
68	* (see copy_semundo, CLONE_SYSVSEM)
69	* - There are two lists of the pending operations: a per-array list
70	* and per-semaphore list (stored in the array). This allows to achieve FIFO
71	* ordering without always scanning all pending operations.
72	* The worst-case behavior is nevertheless O(N^2) for N wakeups.
73	*/
74
75	#include <linux/slab.h>
76	#include <linux/spinlock.h>
77	#include <linux/init.h>
78	#include <linux/proc_fs.h>
79	#include <linux/time.h>
80	#include <linux/security.h>
81	#include <linux/syscalls.h>
82	#include <linux/audit.h>
83	#include <linux/capability.h>
84	#include <linux/seq_file.h>
85	#include <linux/rwsem.h>
86	#include <linux/nsproxy.h>
87	#include <linux/ipc_namespace.h>
88
89	#include <linux/uaccess.h>
90	#include "util.h"
91
92	/* One semaphore structure for each semaphore in the system. */
93	struct sem {
94	int semval; /* current value */
95	/*
96	* PID of the process that last modified the semaphore. For
97	* Linux, specifically these are:
98	* - semop
99	* - semctl, via SETVAL and SETALL.
100	* - at task exit when performing undo adjustments (see exit_sem).
101	*/
102	int sempid;
103	spinlock_t lock; /* spinlock for fine-grained semtimedop */
104	struct list_head pending_alter; /* pending single-sop operations */
105	/* that alter the semaphore */
106	struct list_head pending_const; /* pending single-sop operations */
107	/* that do not alter the semaphore*/
108	time_t sem_otime; /* candidate for sem_otime */
109	} ____cacheline_aligned_in_smp;
110
111	/* One queue for each sleeping process in the system. */
112	struct sem_queue {
113	struct list_head list; /* queue of pending operations */
114	struct task_struct *sleeper; /* this process */
115	struct sem_undo *undo; /* undo structure */
116	int pid; /* process id of requesting process */
117	int status; /* completion status of operation */
118	struct sembuf *sops; /* array of pending operations */
119	struct sembuf *blocking; /* the operation that blocked */
120	int nsops; /* number of operations */
121	int alter; /* does *sops alter the array? */
122	};
123
124	/* Each task has a list of undo requests. They are executed automatically
125	* when the process exits.
126	*/
127	struct sem_undo {
128	struct list_head list_proc; /* per-process list: *
129	* all undos from one process
130	* rcu protected */
131	struct rcu_head rcu; /* rcu struct for sem_undo */
132	struct sem_undo_list *ulp; /* back ptr to sem_undo_list */
133	struct list_head list_id; /* per semaphore array list:
134	* all undos for one array */
135	int semid; /* semaphore set identifier */
136	short *semadj; /* array of adjustments */
137	/* one per semaphore */
138	};
139
140	/* sem_undo_list controls shared access to the list of sem_undo structures
141	* that may be shared among all a CLONE_SYSVSEM task group.
142	*/
143	struct sem_undo_list {
144	atomic_t refcnt;
145	spinlock_t lock;
146	struct list_head list_proc;
147	};
148
149
150	#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
151
152	#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)
153
154	static int newary(struct ipc_namespace *, struct ipc_params *);
155	static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
156	#ifdef CONFIG_PROC_FS
157	static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
158	#endif
159
160	#define SEMMSL_FAST 256 /* 512 bytes on stack */
161	#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
162
163	/*
164	* Locking:
165	* a) global sem_lock() for read/write
166	* sem_undo.id_next,
167	* sem_array.complex_count,
168	* sem_array.complex_mode
169	* sem_array.pending{_alter,_const},
170	* sem_array.sem_undo
171	*
172	* b) global or semaphore sem_lock() for read/write:
173	* sem_array.sem_base[i].pending_{const,alter}:
174	* sem_array.complex_mode (for read)
175	*
176	* c) special:
177	* sem_undo_list.list_proc:
178	* * undo_list->lock for write
179	* * rcu for read
180	*/
181
182	#define sc_semmsl sem_ctls[0]
183	#define sc_semmns sem_ctls[1]
184	#define sc_semopm sem_ctls[2]
185	#define sc_semmni sem_ctls[3]
186
187	void sem_init_ns(struct ipc_namespace *ns)
188	{
189	ns->sc_semmsl = SEMMSL;
190	ns->sc_semmns = SEMMNS;
191	ns->sc_semopm = SEMOPM;
192	ns->sc_semmni = SEMMNI;
193	ns->used_sems = 0;
194	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
195	}
196
197	#ifdef CONFIG_IPC_NS
198	void sem_exit_ns(struct ipc_namespace *ns)
199	{
200	free_ipcs(ns, &sem_ids(ns), freeary);
201	idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
202	}
203	#endif
204
205	void __init sem_init(void)
206	{
207	sem_init_ns(&init_ipc_ns);
208	ipc_init_proc_interface("sysvipc/sem",
209	" key semid perms nsems uid gid cuid cgid otime ctime\n",
210	IPC_SEM_IDS, sysvipc_sem_proc_show);
211	}
212
213	/**
214	* unmerge_queues - unmerge queues, if possible.
215	* @sma: semaphore array
216	*
217	* The function unmerges the wait queues if complex_count is 0.
218	* It must be called prior to dropping the global semaphore array lock.
219	*/
220	static void unmerge_queues(struct sem_array *sma)
221	{
222	struct sem_queue *q, *tq;
223
224	/* complex operations still around? */
225	if (sma->complex_count)
226	return;
227	/*
228	* We will switch back to simple mode.
229	* Move all pending operation back into the per-semaphore
230	* queues.
231	*/
232	list_for_each_entry_safe(q, tq, &sma->pending_alter, list) {
233	struct sem *curr;
234	curr = &sma->sem_base[q->sops[0].sem_num];
235
236	list_add_tail(&q->list, &curr->pending_alter);
237	}
238	INIT_LIST_HEAD(&sma->pending_alter);
239	}
240
241	/**
242	* merge_queues - merge single semop queues into global queue
243	* @sma: semaphore array
244	*
245	* This function merges all per-semaphore queues into the global queue.
246	* It is necessary to achieve FIFO ordering for the pending single-sop
247	* operations when a multi-semop operation must sleep.
248	* Only the alter operations must be moved, the const operations can stay.
249	*/
250	static void merge_queues(struct sem_array *sma)
251	{
252	int i;
253	for (i = 0; i < sma->sem_nsems; i++) {
254	struct sem *sem = sma->sem_base + i;
255
256	list_splice_init(&sem->pending_alter, &sma->pending_alter);
257	}
258	}
259
260	static void sem_rcu_free(struct rcu_head *head)
261	{
262	struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
263	struct sem_array *sma = ipc_rcu_to_struct(p);
264
265	security_sem_free(sma);
266	ipc_rcu_free(head);
267	}
268
269	/*
270	* Enter the mode suitable for non-simple operations:
271	* Caller must own sem_perm.lock.
272	*/
273	static void complexmode_enter(struct sem_array *sma)
274	{
275	int i;
276	struct sem *sem;
277
278	if (sma->complex_mode) {
279	/* We are already in complex_mode. Nothing to do */
280	return;
281	}
282
283	/* We need a full barrier after seting complex_mode:
284	* The write to complex_mode must be visible
285	* before we read the first sem->lock spinlock state.
286	*/
287	smp_store_mb(sma->complex_mode, true);
288
289	for (i = 0; i < sma->sem_nsems; i++) {
290	sem = sma->sem_base + i;
291	spin_unlock_wait(&sem->lock);
292	}
293	/*
294	* spin_unlock_wait() is not a memory barriers, it is only a
295	* control barrier. The code must pair with spin_unlock(&sem->lock),
296	* thus just the control barrier is insufficient.
297	*
298	* smp_rmb() is sufficient, as writes cannot pass the control barrier.
299	*/
300	smp_rmb();
301	}
302
303	/*
304	* Try to leave the mode that disallows simple operations:
305	* Caller must own sem_perm.lock.
306	*/
307	static void complexmode_tryleave(struct sem_array *sma)
308	{
309	if (sma->complex_count) {
310	/* Complex ops are sleeping.
311	* We must stay in complex mode
312	*/
313	return;
314	}
315	/*
316	* Immediately after setting complex_mode to false,
317	* a simple op can start. Thus: all memory writes
318	* performed by the current operation must be visible
319	* before we set complex_mode to false.
320	*/
321	smp_store_release(&sma->complex_mode, false);
322	}
323
324	#define SEM_GLOBAL_LOCK (-1)
325	/*
326	* If the request contains only one semaphore operation, and there are
327	* no complex transactions pending, lock only the semaphore involved.
328	* Otherwise, lock the entire semaphore array, since we either have
329	* multiple semaphores in our own semops, or we need to look at
330	* semaphores from other pending complex operations.
331	*/
332	static inline int sem_lock(struct sem_array *sma, struct sembuf *sops,
333	int nsops)
334	{
335	struct sem *sem;
336
337	if (nsops != 1) {
338	/* Complex operation - acquire a full lock */
339	ipc_lock_object(&sma->sem_perm);
340
341	/* Prevent parallel simple ops */
342	complexmode_enter(sma);
343	return SEM_GLOBAL_LOCK;
344	}
345
346	/*
347	* Only one semaphore affected - try to optimize locking.
348	* Optimized locking is possible if no complex operation
349	* is either enqueued or processed right now.
350	*
351	* Both facts are tracked by complex_mode.
352	*/
353	sem = sma->sem_base + sops->sem_num;
354
355	/*
356	* Initial check for complex_mode. Just an optimization,
357	* no locking, no memory barrier.
358	*/
359	if (!sma->complex_mode) {
360	/*
361	* It appears that no complex operation is around.
362	* Acquire the per-semaphore lock.
363	*/
364	spin_lock(&sem->lock);
365
366	/*
367	* See 51d7d5205d33
368	* ("powerpc: Add smp_mb() to arch_spin_is_locked()"):
369	* A full barrier is required: the write of sem->lock
370	* must be visible before the read is executed
371	*/
372	smp_mb();
373
374	if (!smp_load_acquire(&sma->complex_mode)) {
375	/* fast path successful! */
376	return sops->sem_num;
377	}
378	spin_unlock(&sem->lock);
379	}
380
381	/* slow path: acquire the full lock */
382	ipc_lock_object(&sma->sem_perm);
383
384	if (sma->complex_count == 0) {
385	/* False alarm:
386	* There is no complex operation, thus we can switch
387	* back to the fast path.
388	*/
389	spin_lock(&sem->lock);
390	ipc_unlock_object(&sma->sem_perm);
391	return sops->sem_num;
392	} else {
393	/* Not a false alarm, thus complete the sequence for a
394	* full lock.
395	*/
396	complexmode_enter(sma);
397	return SEM_GLOBAL_LOCK;
398	}
399	}
400
401	static inline void sem_unlock(struct sem_array *sma, int locknum)
402	{
403	if (locknum == SEM_GLOBAL_LOCK) {
404	unmerge_queues(sma);
405	complexmode_tryleave(sma);
406	ipc_unlock_object(&sma->sem_perm);
407	} else {
408	struct sem *sem = sma->sem_base + locknum;
409	spin_unlock(&sem->lock);
410	}
411	}
412
413	/*
414	* sem_lock_(check_) routines are called in the paths where the rwsem
415	* is not held.
416	*
417	* The caller holds the RCU read lock.
418	*/
419	static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns,
420	int id, struct sembuf *sops, int nsops, int *locknum)
421	{
422	struct kern_ipc_perm *ipcp;
423	struct sem_array *sma;
424
425	ipcp = ipc_obtain_object_idr(&sem_ids(ns), id);
426	if (IS_ERR(ipcp))
427	return ERR_CAST(ipcp);
428
429	sma = container_of(ipcp, struct sem_array, sem_perm);
430	*locknum = sem_lock(sma, sops, nsops);
431
432	/* ipc_rmid() may have already freed the ID while sem_lock
433	* was spinning: verify that the structure is still valid
434	*/
435	if (ipc_valid_object(ipcp))
436	return container_of(ipcp, struct sem_array, sem_perm);
437
438	sem_unlock(sma, *locknum);
439	return ERR_PTR(-EINVAL);
440	}
441
442	static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id)
443	{
444	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&sem_ids(ns), id);
445
446	if (IS_ERR(ipcp))
447	return ERR_CAST(ipcp);
448
449	return container_of(ipcp, struct sem_array, sem_perm);
450	}
451
452	static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns,
453	int id)
454	{
455	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id);
456
457	if (IS_ERR(ipcp))
458	return ERR_CAST(ipcp);
459
460	return container_of(ipcp, struct sem_array, sem_perm);
461	}
462
463	static inline void sem_lock_and_putref(struct sem_array *sma)
464	{
465	sem_lock(sma, NULL, -1);
466	ipc_rcu_putref(sma, sem_rcu_free);
467	}
468
469	static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
470	{
471	ipc_rmid(&sem_ids(ns), &s->sem_perm);
472	}
473
474	/*
475	* Lockless wakeup algorithm:
476	* Without the check/retry algorithm a lockless wakeup is possible:
477	* - queue.status is initialized to -EINTR before blocking.
478	* - wakeup is performed by
479	* * unlinking the queue entry from the pending list
480	* * setting queue.status to IN_WAKEUP
481	* This is the notification for the blocked thread that a
482	* result value is imminent.
483	* * call wake_up_process
484	* * set queue.status to the final value.
485	* - the previously blocked thread checks queue.status:
486	* * if it's IN_WAKEUP, then it must wait until the value changes
487	* * if it's not -EINTR, then the operation was completed by
488	* update_queue. semtimedop can return queue.status without
489	* performing any operation on the sem array.
490	* * otherwise it must acquire the spinlock and check what's up.
491	*
492	* The two-stage algorithm is necessary to protect against the following
493	* races:
494	* - if queue.status is set after wake_up_process, then the woken up idle
495	* thread could race forward and try (and fail) to acquire sma->lock
496	* before update_queue had a chance to set queue.status
497	* - if queue.status is written before wake_up_process and if the
498	* blocked process is woken up by a signal between writing
499	* queue.status and the wake_up_process, then the woken up
500	* process could return from semtimedop and die by calling
501	* sys_exit before wake_up_process is called. Then wake_up_process
502	* will oops, because the task structure is already invalid.
503	* (yes, this happened on s390 with sysv msg).
504	*
505	*/
506	#define IN_WAKEUP 1
507
508	/**
509	* newary - Create a new semaphore set
510	* @ns: namespace
511	* @params: ptr to the structure that contains key, semflg and nsems
512	*
513	* Called with sem_ids.rwsem held (as a writer)
514	*/
515	static int newary(struct ipc_namespace *ns, struct ipc_params *params)
516	{
517	int id;
518	int retval;
519	struct sem_array *sma;
520	int size;
521	key_t key = params->key;
522	int nsems = params->u.nsems;
523	int semflg = params->flg;
524	int i;
525
526	if (!nsems)
527	return -EINVAL;
528	if (ns->used_sems + nsems > ns->sc_semmns)
529	return -ENOSPC;
530
531	size = sizeof(*sma) + nsems * sizeof(struct sem);
532	sma = ipc_rcu_alloc(size);
533	if (!sma)
534	return -ENOMEM;
535
536	memset(sma, 0, size);
537
538	sma->sem_perm.mode = (semflg & S_IRWXUGO);
539	sma->sem_perm.key = key;
540
541	sma->sem_perm.security = NULL;
542	retval = security_sem_alloc(sma);
543	if (retval) {
544	ipc_rcu_putref(sma, ipc_rcu_free);
545	return retval;
546	}
547
548	sma->sem_base = (struct sem *) &sma[1];
549
550	for (i = 0; i < nsems; i++) {
551	INIT_LIST_HEAD(&sma->sem_base[i].pending_alter);
552	INIT_LIST_HEAD(&sma->sem_base[i].pending_const);
553	spin_lock_init(&sma->sem_base[i].lock);
554	}
555
556	sma->complex_count = 0;
557	sma->complex_mode = true; /* dropped by sem_unlock below */
558	INIT_LIST_HEAD(&sma->pending_alter);
559	INIT_LIST_HEAD(&sma->pending_const);
560	INIT_LIST_HEAD(&sma->list_id);
561	sma->sem_nsems = nsems;
562	sma->sem_ctime = get_seconds();
563
564	id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
565	if (id < 0) {
566	ipc_rcu_putref(sma, sem_rcu_free);
567	return id;
568	}
569	ns->used_sems += nsems;
570
571	sem_unlock(sma, -1);
572	rcu_read_unlock();
573
574	return sma->sem_perm.id;
575	}
576
577
578	/*
579	* Called with sem_ids.rwsem and ipcp locked.
580	*/
581	static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
582	{
583	struct sem_array *sma;
584
585	sma = container_of(ipcp, struct sem_array, sem_perm);
586	return security_sem_associate(sma, semflg);
587	}
588
589	/*
590	* Called with sem_ids.rwsem and ipcp locked.
591	*/
592	static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
593	struct ipc_params *params)
594	{
595	struct sem_array *sma;
596
597	sma = container_of(ipcp, struct sem_array, sem_perm);
598	if (params->u.nsems > sma->sem_nsems)
599	return -EINVAL;
600
601	return 0;
602	}
603
604	SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
605	{
606	struct ipc_namespace *ns;
607	static const struct ipc_ops sem_ops = {
608	.getnew = newary,
609	.associate = sem_security,
610	.more_checks = sem_more_checks,
611	};
612	struct ipc_params sem_params;
613
614	ns = current->nsproxy->ipc_ns;
615
616	if (nsems < 0 || nsems > ns->sc_semmsl)
617	return -EINVAL;
618
619	sem_params.key = key;
620	sem_params.flg = semflg;
621	sem_params.u.nsems = nsems;
622
623	return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
624	}
625
626	/**
627	* perform_atomic_semop - Perform (if possible) a semaphore operation
628	* @sma: semaphore array
629	* @q: struct sem_queue that describes the operation
630	*
631	* Returns 0 if the operation was possible.
632	* Returns 1 if the operation is impossible, the caller must sleep.
633	* Negative values are error codes.
634	*/
635	static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q)
636	{
637	int result, sem_op, nsops, pid;
638	struct sembuf *sop;
639	struct sem *curr;
640	struct sembuf *sops;
641	struct sem_undo *un;
642
643	sops = q->sops;
644	nsops = q->nsops;
645	un = q->undo;
646
647	for (sop = sops; sop < sops + nsops; sop++) {
648	curr = sma->sem_base + sop->sem_num;
649	sem_op = sop->sem_op;
650	result = curr->semval;
651
652	if (!sem_op && result)
653	goto would_block;
654
655	result += sem_op;
656	if (result < 0)
657	goto would_block;
658	if (result > SEMVMX)
659	goto out_of_range;
660
661	if (sop->sem_flg & SEM_UNDO) {
662	int undo = un->semadj[sop->sem_num] - sem_op;
663	/* Exceeding the undo range is an error. */
664	if (undo < (-SEMAEM - 1) || undo > SEMAEM)
665	goto out_of_range;
666	un->semadj[sop->sem_num] = undo;
667	}
668
669	curr->semval = result;
670	}
671
672	sop--;
673	pid = q->pid;
674	while (sop >= sops) {
675	sma->sem_base[sop->sem_num].sempid = pid;
676	sop--;
677	}
678
679	return 0;
680
681	out_of_range:
682	result = -ERANGE;
683	goto undo;
684
685	would_block:
686	q->blocking = sop;
687
688	if (sop->sem_flg & IPC_NOWAIT)
689	result = -EAGAIN;
690	else
691	result = 1;
692
693	undo:
694	sop--;
695	while (sop >= sops) {
696	sem_op = sop->sem_op;
697	sma->sem_base[sop->sem_num].semval -= sem_op;
698	if (sop->sem_flg & SEM_UNDO)
699	un->semadj[sop->sem_num] += sem_op;
700	sop--;
701	}
702
703	return result;
704	}
705
706	/** wake_up_sem_queue_prepare(q, error): Prepare wake-up
707	* @q: queue entry that must be signaled
708	* @error: Error value for the signal
709	*
710	* Prepare the wake-up of the queue entry q.
711	*/
712	static void wake_up_sem_queue_prepare(struct list_head *pt,
713	struct sem_queue *q, int error)
714	{
715	if (list_empty(pt)) {
716	/*
717	* Hold preempt off so that we don't get preempted and have the
718	* wakee busy-wait until we're scheduled back on.
719	*/
720	preempt_disable();
721	}
722	q->status = IN_WAKEUP;
723	q->pid = error;
724
725	list_add_tail(&q->list, pt);
726	}
727
728	/**
729	* wake_up_sem_queue_do - do the actual wake-up
730	* @pt: list of tasks to be woken up
731	*
732	* Do the actual wake-up.
733	* The function is called without any locks held, thus the semaphore array
734	* could be destroyed already and the tasks can disappear as soon as the
735	* status is set to the actual return code.
736	*/
737	static void wake_up_sem_queue_do(struct list_head *pt)
738	{
739	struct sem_queue *q, *t;
740	int did_something;
741
742	did_something = !list_empty(pt);
743	list_for_each_entry_safe(q, t, pt, list) {
744	wake_up_process(q->sleeper);
745	/* q can disappear immediately after writing q->status. */
746	smp_wmb();
747	q->status = q->pid;
748	}
749	if (did_something)
750	preempt_enable();
751	}
752
753	static void unlink_queue(struct sem_array *sma, struct sem_queue *q)
754	{
755	list_del(&q->list);
756	if (q->nsops > 1)
757	sma->complex_count--;
758	}
759
760	/** check_restart(sma, q)
761	* @sma: semaphore array
762	* @q: the operation that just completed
763	*
764	* update_queue is O(N^2) when it restarts scanning the whole queue of
765	* waiting operations. Therefore this function checks if the restart is
766	* really necessary. It is called after a previously waiting operation
767	* modified the array.
768	* Note that wait-for-zero operations are handled without restart.
769	*/
770	static int check_restart(struct sem_array *sma, struct sem_queue *q)
771	{
772	/* pending complex alter operations are too difficult to analyse */
773	if (!list_empty(&sma->pending_alter))
774	return 1;
775
776	/* we were a sleeping complex operation. Too difficult */
777	if (q->nsops > 1)
778	return 1;
779
780	/* It is impossible that someone waits for the new value:
781	* - complex operations always restart.
782	* - wait-for-zero are handled seperately.
783	* - q is a previously sleeping simple operation that
784	* altered the array. It must be a decrement, because
785	* simple increments never sleep.
786	* - If there are older (higher priority) decrements
787	* in the queue, then they have observed the original
788	* semval value and couldn't proceed. The operation
789	* decremented to value - thus they won't proceed either.
790	*/
791	return 0;
792	}
793
794	/**
795	* wake_const_ops - wake up non-alter tasks
796	* @sma: semaphore array.
797	* @semnum: semaphore that was modified.
798	* @pt: list head for the tasks that must be woken up.
799	*
800	* wake_const_ops must be called after a semaphore in a semaphore array
801	* was set to 0. If complex const operations are pending, wake_const_ops must
802	* be called with semnum = -1, as well as with the number of each modified
803	* semaphore.
804	* The tasks that must be woken up are added to @pt. The return code
805	* is stored in q->pid.
806	* The function returns 1 if at least one operation was completed successfully.
807	*/
808	static int wake_const_ops(struct sem_array *sma, int semnum,
809	struct list_head *pt)
810	{
811	struct sem_queue *q;
812	struct list_head *walk;
813	struct list_head *pending_list;
814	int semop_completed = 0;
815
816	if (semnum == -1)
817	pending_list = &sma->pending_const;
818	else
819	pending_list = &sma->sem_base[semnum].pending_const;
820
821	walk = pending_list->next;
822	while (walk != pending_list) {
823	int error;
824
825	q = container_of(walk, struct sem_queue, list);
826	walk = walk->next;
827
828	error = perform_atomic_semop(sma, q);
829
830	if (error <= 0) {
831	/* operation completed, remove from queue & wakeup */
832
833	unlink_queue(sma, q);
834
835	wake_up_sem_queue_prepare(pt, q, error);
836	if (error == 0)
837	semop_completed = 1;
838	}
839	}
840	return semop_completed;
841	}
842
843	/**
844	* do_smart_wakeup_zero - wakeup all wait for zero tasks
845	* @sma: semaphore array
846	* @sops: operations that were performed
847	* @nsops: number of operations
848	* @pt: list head of the tasks that must be woken up.
849	*
850	* Checks all required queue for wait-for-zero operations, based
851	* on the actual changes that were performed on the semaphore array.
852	* The function returns 1 if at least one operation was completed successfully.
853	*/
854	static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops,
855	int nsops, struct list_head *pt)
856	{
857	int i;
858	int semop_completed = 0;
859	int got_zero = 0;
860
861	/* first: the per-semaphore queues, if known */
862	if (sops) {
863	for (i = 0; i < nsops; i++) {
864	int num = sops[i].sem_num;
865
866	if (sma->sem_base[num].semval == 0) {
867	got_zero = 1;
868	semop_completed |= wake_const_ops(sma, num, pt);
869	}
870	}
871	} else {
872	/*
873	* No sops means modified semaphores not known.
874	* Assume all were changed.
875	*/
876	for (i = 0; i < sma->sem_nsems; i++) {
877	if (sma->sem_base[i].semval == 0) {
878	got_zero = 1;
879	semop_completed |= wake_const_ops(sma, i, pt);
880	}
881	}
882	}
883	/*
884	* If one of the modified semaphores got 0,
885	* then check the global queue, too.
886	*/
887	if (got_zero)
888	semop_completed |= wake_const_ops(sma, -1, pt);
889
890	return semop_completed;
891	}
892
893
894	/**
895	* update_queue - look for tasks that can be completed.
896	* @sma: semaphore array.
897	* @semnum: semaphore that was modified.
898	* @pt: list head for the tasks that must be woken up.
899	*
900	* update_queue must be called after a semaphore in a semaphore array
901	* was modified. If multiple semaphores were modified, update_queue must
902	* be called with semnum = -1, as well as with the number of each modified
903	* semaphore.
904	* The tasks that must be woken up are added to @pt. The return code
905	* is stored in q->pid.
906	* The function internally checks if const operations can now succeed.
907	*
908	* The function return 1 if at least one semop was completed successfully.
909	*/
910	static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt)
911	{
912	struct sem_queue *q;
913	struct list_head *walk;
914	struct list_head *pending_list;
915	int semop_completed = 0;
916
917	if (semnum == -1)
918	pending_list = &sma->pending_alter;
919	else
920	pending_list = &sma->sem_base[semnum].pending_alter;
921
922	again:
923	walk = pending_list->next;
924	while (walk != pending_list) {
925	int error, restart;
926
927	q = container_of(walk, struct sem_queue, list);
928	walk = walk->next;
929
930	/* If we are scanning the single sop, per-semaphore list of
931	* one semaphore and that semaphore is 0, then it is not
932	* necessary to scan further: simple increments
933	* that affect only one entry succeed immediately and cannot
934	* be in the per semaphore pending queue, and decrements
935	* cannot be successful if the value is already 0.
936	*/
937	if (semnum != -1 && sma->sem_base[semnum].semval == 0)
938	break;
939
940	error = perform_atomic_semop(sma, q);
941
942	/* Does q->sleeper still need to sleep? */
943	if (error > 0)
944	continue;
945
946	unlink_queue(sma, q);
947
948	if (error) {
949	restart = 0;
950	} else {
951	semop_completed = 1;
952	do_smart_wakeup_zero(sma, q->sops, q->nsops, pt);
953	restart = check_restart(sma, q);
954	}
955
956	wake_up_sem_queue_prepare(pt, q, error);
957	if (restart)
958	goto again;
959	}
960	return semop_completed;
961	}
962
963	/**
964	* set_semotime - set sem_otime
965	* @sma: semaphore array
966	* @sops: operations that modified the array, may be NULL
967	*
968	* sem_otime is replicated to avoid cache line trashing.
969	* This function sets one instance to the current time.
970	*/
971	static void set_semotime(struct sem_array *sma, struct sembuf *sops)
972	{
973	if (sops == NULL) {
974	sma->sem_base[0].sem_otime = get_seconds();
975	} else {
976	sma->sem_base[sops[0].sem_num].sem_otime =
977	get_seconds();
978	}
979	}
980
981	/**
982	* do_smart_update - optimized update_queue
983	* @sma: semaphore array
984	* @sops: operations that were performed
985	* @nsops: number of operations
986	* @otime: force setting otime
987	* @pt: list head of the tasks that must be woken up.
988	*
989	* do_smart_update() does the required calls to update_queue and wakeup_zero,
990	* based on the actual changes that were performed on the semaphore array.
991	* Note that the function does not do the actual wake-up: the caller is
992	* responsible for calling wake_up_sem_queue_do(@pt).
993	* It is safe to perform this call after dropping all locks.
994	*/
995	static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops,
996	int otime, struct list_head *pt)
997	{
998	int i;
999
1000	otime |= do_smart_wakeup_zero(sma, sops, nsops, pt);
1001
1002	if (!list_empty(&sma->pending_alter)) {
1003	/* semaphore array uses the global queue - just process it. */
1004	otime |= update_queue(sma, -1, pt);
1005	} else {
1006	if (!sops) {
1007	/*
1008	* No sops, thus the modified semaphores are not
1009	* known. Check all.
1010	*/
1011	for (i = 0; i < sma->sem_nsems; i++)
1012	otime |= update_queue(sma, i, pt);
1013	} else {
1014	/*
1015	* Check the semaphores that were increased:
1016	* - No complex ops, thus all sleeping ops are
1017	* decrease.
1018	* - if we decreased the value, then any sleeping
1019	* semaphore ops wont be able to run: If the
1020	* previous value was too small, then the new
1021	* value will be too small, too.
1022	*/
1023	for (i = 0; i < nsops; i++) {
1024	if (sops[i].sem_op > 0) {
1025	otime |= update_queue(sma,
1026	sops[i].sem_num, pt);
1027	}
1028	}
1029	}
1030	}
1031	if (otime)
1032	set_semotime(sma, sops);
1033	}
1034
1035	/*
1036	* check_qop: Test if a queued operation sleeps on the semaphore semnum
1037	*/
1038	static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q,
1039	bool count_zero)
1040	{
1041	struct sembuf *sop = q->blocking;
1042
1043	/*
1044	* Linux always (since 0.99.10) reported a task as sleeping on all
1045	* semaphores. This violates SUS, therefore it was changed to the
1046	* standard compliant behavior.
1047	* Give the administrators a chance to notice that an application
1048	* might misbehave because it relies on the Linux behavior.
1049	*/
1050	pr_info_once("semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant.\n"
1051	"The task %s (%d) triggered the difference, watch for misbehavior.\n",
1052	current->comm, task_pid_nr(current));
1053
1054	if (sop->sem_num != semnum)
1055	return 0;
1056
1057	if (count_zero && sop->sem_op == 0)
1058	return 1;
1059	if (!count_zero && sop->sem_op < 0)
1060	return 1;
1061
1062	return 0;
1063	}
1064
1065	/* The following counts are associated to each semaphore:
1066	* semncnt number of tasks waiting on semval being nonzero
1067	* semzcnt number of tasks waiting on semval being zero
1068	*
1069	* Per definition, a task waits only on the semaphore of the first semop
1070	* that cannot proceed, even if additional operation would block, too.
1071	*/
1072	static int count_semcnt(struct sem_array *sma, ushort semnum,
1073	bool count_zero)
1074	{
1075	struct list_head *l;
1076	struct sem_queue *q;
1077	int semcnt;
1078
1079	semcnt = 0;
1080	/* First: check the simple operations. They are easy to evaluate */
1081	if (count_zero)
1082	l = &sma->sem_base[semnum].pending_const;
1083	else
1084	l = &sma->sem_base[semnum].pending_alter;
1085
1086	list_for_each_entry(q, l, list) {
1087	/* all task on a per-semaphore list sleep on exactly
1088	* that semaphore
1089	*/
1090	semcnt++;
1091	}
1092
1093	/* Then: check the complex operations. */
1094	list_for_each_entry(q, &sma->pending_alter, list) {
1095	semcnt += check_qop(sma, semnum, q, count_zero);
1096	}
1097	if (count_zero) {
1098	list_for_each_entry(q, &sma->pending_const, list) {
1099	semcnt += check_qop(sma, semnum, q, count_zero);
1100	}
1101	}
1102	return semcnt;
1103	}
1104
1105	/* Free a semaphore set. freeary() is called with sem_ids.rwsem locked
1106	* as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem
1107	* remains locked on exit.
1108	*/
1109	static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
1110	{
1111	struct sem_undo *un, *tu;
1112	struct sem_queue *q, *tq;
1113	struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
1114	struct list_head tasks;
1115	int i;
1116
1117	/* Free the existing undo structures for this semaphore set. */
1118	ipc_assert_locked_object(&sma->sem_perm);
1119	list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
1120	list_del(&un->list_id);
1121	spin_lock(&un->ulp->lock);
1122	un->semid = -1;
1123	list_del_rcu(&un->list_proc);
1124	spin_unlock(&un->ulp->lock);
1125	kfree_rcu(un, rcu);
1126	}
1127
1128	/* Wake up all pending processes and let them fail with EIDRM. */
1129	INIT_LIST_HEAD(&tasks);
1130	list_for_each_entry_safe(q, tq, &sma->pending_const, list) {
1131	unlink_queue(sma, q);
1132	wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
1133	}
1134
1135	list_for_each_entry_safe(q, tq, &sma->pending_alter, list) {
1136	unlink_queue(sma, q);
1137	wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
1138	}
1139	for (i = 0; i < sma->sem_nsems; i++) {
1140	struct sem *sem = sma->sem_base + i;
1141	list_for_each_entry_safe(q, tq, &sem->pending_const, list) {
1142	unlink_queue(sma, q);
1143	wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
1144	}
1145	list_for_each_entry_safe(q, tq, &sem->pending_alter, list) {
1146	unlink_queue(sma, q);
1147	wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
1148	}
1149	}
1150
1151	/* Remove the semaphore set from the IDR */
1152	sem_rmid(ns, sma);
1153	sem_unlock(sma, -1);
1154	rcu_read_unlock();
1155
1156	wake_up_sem_queue_do(&tasks);
1157	ns->used_sems -= sma->sem_nsems;
1158	ipc_rcu_putref(sma, sem_rcu_free);
1159	}
1160
1161	static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
1162	{
1163	switch (version) {
1164	case IPC_64:
1165	return copy_to_user(buf, in, sizeof(*in));
1166	case IPC_OLD:
1167	{
1168	struct semid_ds out;
1169
1170	memset(&out, 0, sizeof(out));
1171
1172	ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
1173
1174	out.sem_otime = in->sem_otime;
1175	out.sem_ctime = in->sem_ctime;
1176	out.sem_nsems = in->sem_nsems;
1177
1178	return copy_to_user(buf, &out, sizeof(out));
1179	}
1180	default:
1181	return -EINVAL;
1182	}
1183	}
1184
1185	static time_t get_semotime(struct sem_array *sma)
1186	{
1187	int i;
1188	time_t res;
1189
1190	res = sma->sem_base[0].sem_otime;
1191	for (i = 1; i < sma->sem_nsems; i++) {
1192	time_t to = sma->sem_base[i].sem_otime;
1193
1194	if (to > res)
1195	res = to;
1196	}
1197	return res;
1198	}
1199
1200	static int semctl_nolock(struct ipc_namespace *ns, int semid,
1201	int cmd, int version, void __user *p)
1202	{
1203	int err;
1204	struct sem_array *sma;
1205
1206	switch (cmd) {
1207	case IPC_INFO:
1208	case SEM_INFO:
1209	{
1210	struct seminfo seminfo;
1211	int max_id;
1212
1213	err = security_sem_semctl(NULL, cmd);
1214	if (err)
1215	return err;
1216
1217	memset(&seminfo, 0, sizeof(seminfo));
1218	seminfo.semmni = ns->sc_semmni;
1219	seminfo.semmns = ns->sc_semmns;
1220	seminfo.semmsl = ns->sc_semmsl;
1221	seminfo.semopm = ns->sc_semopm;
1222	seminfo.semvmx = SEMVMX;
1223	seminfo.semmnu = SEMMNU;
1224	seminfo.semmap = SEMMAP;
1225	seminfo.semume = SEMUME;
1226	down_read(&sem_ids(ns).rwsem);
1227	if (cmd == SEM_INFO) {
1228	seminfo.semusz = sem_ids(ns).in_use;
1229	seminfo.semaem = ns->used_sems;
1230	} else {
1231	seminfo.semusz = SEMUSZ;
1232	seminfo.semaem = SEMAEM;
1233	}
1234	max_id = ipc_get_maxid(&sem_ids(ns));
1235	up_read(&sem_ids(ns).rwsem);
1236	if (copy_to_user(p, &seminfo, sizeof(struct seminfo)))
1237	return -EFAULT;
1238	return (max_id < 0) ? 0 : max_id;
1239	}
1240	case IPC_STAT:
1241	case SEM_STAT:
1242	{
1243	struct semid64_ds tbuf;
1244	int id = 0;
1245
1246	memset(&tbuf, 0, sizeof(tbuf));
1247
1248	rcu_read_lock();
1249	if (cmd == SEM_STAT) {
1250	sma = sem_obtain_object(ns, semid);
1251	if (IS_ERR(sma)) {
1252	err = PTR_ERR(sma);
1253	goto out_unlock;
1254	}
1255	id = sma->sem_perm.id;
1256	} else {
1257	sma = sem_obtain_object_check(ns, semid);
1258	if (IS_ERR(sma)) {
1259	err = PTR_ERR(sma);
1260	goto out_unlock;
1261	}
1262	}
1263
1264	err = -EACCES;
1265	if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
1266	goto out_unlock;
1267
1268	err = security_sem_semctl(sma, cmd);
1269	if (err)
1270	goto out_unlock;
1271
1272	kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
1273	tbuf.sem_otime = get_semotime(sma);
1274	tbuf.sem_ctime = sma->sem_ctime;
1275	tbuf.sem_nsems = sma->sem_nsems;
1276	rcu_read_unlock();
1277	if (copy_semid_to_user(p, &tbuf, version))
1278	return -EFAULT;
1279	return id;
1280	}
1281	default:
1282	return -EINVAL;
1283	}
1284	out_unlock:
1285	rcu_read_unlock();
1286	return err;
1287	}
1288
1289	static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
1290	unsigned long arg)
1291	{
1292	struct sem_undo *un;
1293	struct sem_array *sma;
1294	struct sem *curr;
1295	int err;
1296	struct list_head tasks;
1297	int val;
1298	#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
1299	/* big-endian 64bit */
1300	val = arg >> 32;
1301	#else
1302	/* 32bit or little-endian 64bit */
1303	val = arg;
1304	#endif
1305
1306	if (val > SEMVMX || val < 0)
1307	return -ERANGE;
1308
1309	INIT_LIST_HEAD(&tasks);
1310
1311	rcu_read_lock();
1312	sma = sem_obtain_object_check(ns, semid);
1313	if (IS_ERR(sma)) {
1314	rcu_read_unlock();
1315	return PTR_ERR(sma);
1316	}
1317
1318	if (semnum < 0 || semnum >= sma->sem_nsems) {
1319	rcu_read_unlock();
1320	return -EINVAL;
1321	}
1322
1323
1324	if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) {
1325	rcu_read_unlock();
1326	return -EACCES;
1327	}
1328
1329	err = security_sem_semctl(sma, SETVAL);
1330	if (err) {
1331	rcu_read_unlock();
1332	return -EACCES;
1333	}
1334
1335	sem_lock(sma, NULL, -1);
1336
1337	if (!ipc_valid_object(&sma->sem_perm)) {
1338	sem_unlock(sma, -1);
1339	rcu_read_unlock();
1340	return -EIDRM;
1341	}
1342
1343	curr = &sma->sem_base[semnum];
1344
1345	ipc_assert_locked_object(&sma->sem_perm);
1346	list_for_each_entry(un, &sma->list_id, list_id)
1347	un->semadj[semnum] = 0;
1348
1349	curr->semval = val;
1350	curr->sempid = task_tgid_vnr(current);
1351	sma->sem_ctime = get_seconds();
1352	/* maybe some queued-up processes were waiting for this */
1353	do_smart_update(sma, NULL, 0, 0, &tasks);
1354	sem_unlock(sma, -1);
1355	rcu_read_unlock();
1356	wake_up_sem_queue_do(&tasks);
1357	return 0;
1358	}
1359
1360	static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
1361	int cmd, void __user *p)
1362	{
1363	struct sem_array *sma;
1364	struct sem *curr;
1365	int err, nsems;
1366	ushort fast_sem_io[SEMMSL_FAST];
1367	ushort *sem_io = fast_sem_io;
1368	struct list_head tasks;
1369
1370	INIT_LIST_HEAD(&tasks);
1371
1372	rcu_read_lock();
1373	sma = sem_obtain_object_check(ns, semid);
1374	if (IS_ERR(sma)) {
1375	rcu_read_unlock();
1376	return PTR_ERR(sma);
1377	}
1378
1379	nsems = sma->sem_nsems;
1380
1381	err = -EACCES;
1382	if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
1383	goto out_rcu_wakeup;
1384
1385	err = security_sem_semctl(sma, cmd);
1386	if (err)
1387	goto out_rcu_wakeup;
1388
1389	err = -EACCES;
1390	switch (cmd) {
1391	case GETALL:
1392	{
1393	ushort __user *array = p;
1394	int i;
1395
1396	sem_lock(sma, NULL, -1);
1397	if (!ipc_valid_object(&sma->sem_perm)) {
1398	err = -EIDRM;
1399	goto out_unlock;
1400	}
1401	if (nsems > SEMMSL_FAST) {
1402	if (!ipc_rcu_getref(sma)) {
1403	err = -EIDRM;
1404	goto out_unlock;
1405	}
1406	sem_unlock(sma, -1);
1407	rcu_read_unlock();
1408	sem_io = ipc_alloc(sizeof(ushort)*nsems);
1409	if (sem_io == NULL) {
1410	ipc_rcu_putref(sma, sem_rcu_free);
1411	return -ENOMEM;
1412	}
1413
1414	rcu_read_lock();
1415	sem_lock_and_putref(sma);
1416	if (!ipc_valid_object(&sma->sem_perm)) {
1417	err = -EIDRM;
1418	goto out_unlock;
1419	}
1420	}
1421	for (i = 0; i < sma->sem_nsems; i++)
1422	sem_io[i] = sma->sem_base[i].semval;
1423	sem_unlock(sma, -1);
1424	rcu_read_unlock();
1425	err = 0;
1426	if (copy_to_user(array, sem_io, nsems*sizeof(ushort)))
1427	err = -EFAULT;
1428	goto out_free;
1429	}
1430	case SETALL:
1431	{
1432	int i;
1433	struct sem_undo *un;
1434
1435	if (!ipc_rcu_getref(sma)) {
1436	err = -EIDRM;
1437	goto out_rcu_wakeup;
1438	}
1439	rcu_read_unlock();
1440
1441	if (nsems > SEMMSL_FAST) {
1442	sem_io = ipc_alloc(sizeof(ushort)*nsems);
1443	if (sem_io == NULL) {
1444	ipc_rcu_putref(sma, sem_rcu_free);
1445	return -ENOMEM;
1446	}
1447	}
1448
1449	if (copy_from_user(sem_io, p, nsems*sizeof(ushort))) {
1450	ipc_rcu_putref(sma, sem_rcu_free);
1451	err = -EFAULT;
1452	goto out_free;
1453	}
1454
1455	for (i = 0; i < nsems; i++) {
1456	if (sem_io[i] > SEMVMX) {
1457	ipc_rcu_putref(sma, sem_rcu_free);
1458	err = -ERANGE;
1459	goto out_free;
1460	}
1461	}
1462	rcu_read_lock();
1463	sem_lock_and_putref(sma);
1464	if (!ipc_valid_object(&sma->sem_perm)) {
1465	err = -EIDRM;
1466	goto out_unlock;
1467	}
1468
1469	for (i = 0; i < nsems; i++) {
1470	sma->sem_base[i].semval = sem_io[i];
1471	sma->sem_base[i].sempid = task_tgid_vnr(current);
1472	}
1473
1474	ipc_assert_locked_object(&sma->sem_perm);
1475	list_for_each_entry(un, &sma->list_id, list_id) {
1476	for (i = 0; i < nsems; i++)
1477	un->semadj[i] = 0;
1478	}
1479	sma->sem_ctime = get_seconds();
1480	/* maybe some queued-up processes were waiting for this */
1481	do_smart_update(sma, NULL, 0, 0, &tasks);
1482	err = 0;
1483	goto out_unlock;
1484	}
1485	/* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */
1486	}
1487	err = -EINVAL;
1488	if (semnum < 0 || semnum >= nsems)
1489	goto out_rcu_wakeup;
1490
1491	sem_lock(sma, NULL, -1);
1492	if (!ipc_valid_object(&sma->sem_perm)) {
1493	err = -EIDRM;
1494	goto out_unlock;
1495	}
1496	curr = &sma->sem_base[semnum];
1497
1498	switch (cmd) {
1499	case GETVAL:
1500	err = curr->semval;
1501	goto out_unlock;
1502	case GETPID:
1503	err = curr->sempid;
1504	goto out_unlock;
1505	case GETNCNT:
1506	err = count_semcnt(sma, semnum, 0);
1507	goto out_unlock;
1508	case GETZCNT:
1509	err = count_semcnt(sma, semnum, 1);
1510	goto out_unlock;
1511	}
1512
1513	out_unlock:
1514	sem_unlock(sma, -1);
1515	out_rcu_wakeup:
1516	rcu_read_unlock();
1517	wake_up_sem_queue_do(&tasks);
1518	out_free:
1519	if (sem_io != fast_sem_io)
1520	ipc_free(sem_io);
1521	return err;
1522	}
1523
1524	static inline unsigned long
1525	copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
1526	{
1527	switch (version) {
1528	case IPC_64:
1529	if (copy_from_user(out, buf, sizeof(*out)))
1530	return -EFAULT;
1531	return 0;
1532	case IPC_OLD:
1533	{
1534	struct semid_ds tbuf_old;
1535
1536	if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
1537	return -EFAULT;
1538
1539	out->sem_perm.uid = tbuf_old.sem_perm.uid;
1540	out->sem_perm.gid = tbuf_old.sem_perm.gid;
1541	out->sem_perm.mode = tbuf_old.sem_perm.mode;
1542
1543	return 0;
1544	}
1545	default:
1546	return -EINVAL;
1547	}
1548	}
1549
1550	/*
1551	* This function handles some semctl commands which require the rwsem
1552	* to be held in write mode.
1553	* NOTE: no locks must be held, the rwsem is taken inside this function.
1554	*/
1555	static int semctl_down(struct ipc_namespace *ns, int semid,
1556	int cmd, int version, void __user *p)
1557	{
1558	struct sem_array *sma;
1559	int err;
1560	struct semid64_ds semid64;
1561	struct kern_ipc_perm *ipcp;
1562
1563	if (cmd == IPC_SET) {
1564	if (copy_semid_from_user(&semid64, p, version))
1565	return -EFAULT;
1566	}
1567
1568	down_write(&sem_ids(ns).rwsem);
1569	rcu_read_lock();
1570
1571	ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd,
1572	&semid64.sem_perm, 0);
1573	if (IS_ERR(ipcp)) {
1574	err = PTR_ERR(ipcp);
1575	goto out_unlock1;
1576	}
1577
1578	sma = container_of(ipcp, struct sem_array, sem_perm);
1579
1580	err = security_sem_semctl(sma, cmd);
1581	if (err)
1582	goto out_unlock1;
1583
1584	switch (cmd) {
1585	case IPC_RMID:
1586	sem_lock(sma, NULL, -1);
1587	/* freeary unlocks the ipc object and rcu */
1588	freeary(ns, ipcp);
1589	goto out_up;
1590	case IPC_SET:
1591	sem_lock(sma, NULL, -1);
1592	err = ipc_update_perm(&semid64.sem_perm, ipcp);
1593	if (err)
1594	goto out_unlock0;
1595	sma->sem_ctime = get_seconds();
1596	break;
1597	default:
1598	err = -EINVAL;
1599	goto out_unlock1;
1600	}
1601
1602	out_unlock0:
1603	sem_unlock(sma, -1);
1604	out_unlock1:
1605	rcu_read_unlock();
1606	out_up:
1607	up_write(&sem_ids(ns).rwsem);
1608	return err;
1609	}
1610
1611	SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg)
1612	{
1613	int version;
1614	struct ipc_namespace *ns;
1615	void __user *p = (void __user *)arg;
1616
1617	if (semid < 0)
1618	return -EINVAL;
1619
1620	version = ipc_parse_version(&cmd);
1621	ns = current->nsproxy->ipc_ns;
1622
1623	switch (cmd) {
1624	case IPC_INFO:
1625	case SEM_INFO:
1626	case IPC_STAT:
1627	case SEM_STAT:
1628	return semctl_nolock(ns, semid, cmd, version, p);
1629	case GETALL:
1630	case GETVAL:
1631	case GETPID:
1632	case GETNCNT:
1633	case GETZCNT:
1634	case SETALL:
1635	return semctl_main(ns, semid, semnum, cmd, p);
1636	case SETVAL:
1637	return semctl_setval(ns, semid, semnum, arg);
1638	case IPC_RMID:
1639	case IPC_SET:
1640	return semctl_down(ns, semid, cmd, version, p);
1641	default:
1642	return -EINVAL;
1643	}
1644	}
1645
1646	/* If the task doesn't already have a undo_list, then allocate one
1647	* here. We guarantee there is only one thread using this undo list,
1648	* and current is THE ONE
1649	*
1650	* If this allocation and assignment succeeds, but later
1651	* portions of this code fail, there is no need to free the sem_undo_list.
1652	* Just let it stay associated with the task, and it'll be freed later
1653	* at exit time.
1654	*
1655	* This can block, so callers must hold no locks.
1656	*/
1657	static inline int get_undo_list(struct sem_undo_list **undo_listp)
1658	{
1659	struct sem_undo_list *undo_list;
1660
1661	undo_list = current->sysvsem.undo_list;
1662	if (!undo_list) {
1663	undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
1664	if (undo_list == NULL)
1665	return -ENOMEM;
1666	spin_lock_init(&undo_list->lock);
1667	atomic_set(&undo_list->refcnt, 1);
1668	INIT_LIST_HEAD(&undo_list->list_proc);
1669
1670	current->sysvsem.undo_list = undo_list;
1671	}
1672	*undo_listp = undo_list;
1673	return 0;
1674	}
1675
1676	static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
1677	{
1678	struct sem_undo *un;
1679
1680	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
1681	if (un->semid == semid)
1682	return un;
1683	}
1684	return NULL;
1685	}
1686
1687	static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1688	{
1689	struct sem_undo *un;
1690
1691	assert_spin_locked(&ulp->lock);
1692
1693	un = __lookup_undo(ulp, semid);
1694	if (un) {
1695	list_del_rcu(&un->list_proc);
1696	list_add_rcu(&un->list_proc, &ulp->list_proc);
1697	}
1698	return un;
1699	}
1700
1701	/**
1702	* find_alloc_undo - lookup (and if not present create) undo array
1703	* @ns: namespace
1704	* @semid: semaphore array id
1705	*
1706	* The function looks up (and if not present creates) the undo structure.
1707	* The size of the undo structure depends on the size of the semaphore
1708	* array, thus the alloc path is not that straightforward.
1709	* Lifetime-rules: sem_undo is rcu-protected, on success, the function
1710	* performs a rcu_read_lock().
1711	*/
1712	static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
1713	{
1714	struct sem_array *sma;
1715	struct sem_undo_list *ulp;
1716	struct sem_undo *un, *new;
1717	int nsems, error;
1718
1719	error = get_undo_list(&ulp);
1720	if (error)
1721	return ERR_PTR(error);
1722
1723	rcu_read_lock();
1724	spin_lock(&ulp->lock);
1725	un = lookup_undo(ulp, semid);
1726	spin_unlock(&ulp->lock);
1727	if (likely(un != NULL))
1728	goto out;
1729
1730	/* no undo structure around - allocate one. */
1731	/* step 1: figure out the size of the semaphore array */
1732	sma = sem_obtain_object_check(ns, semid);
1733	if (IS_ERR(sma)) {
1734	rcu_read_unlock();
1735	return ERR_CAST(sma);
1736	}
1737
1738	nsems = sma->sem_nsems;
1739	if (!ipc_rcu_getref(sma)) {
1740	rcu_read_unlock();
1741	un = ERR_PTR(-EIDRM);
1742	goto out;
1743	}
1744	rcu_read_unlock();
1745
1746	/* step 2: allocate new undo structure */
1747	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
1748	if (!new) {
1749	ipc_rcu_putref(sma, sem_rcu_free);
1750	return ERR_PTR(-ENOMEM);
1751	}
1752
1753	/* step 3: Acquire the lock on semaphore array */
1754	rcu_read_lock();
1755	sem_lock_and_putref(sma);
1756	if (!ipc_valid_object(&sma->sem_perm)) {
1757	sem_unlock(sma, -1);
1758	rcu_read_unlock();
1759	kfree(new);
1760	un = ERR_PTR(-EIDRM);
1761	goto out;
1762	}
1763	spin_lock(&ulp->lock);
1764
1765	/*
1766	* step 4: check for races: did someone else allocate the undo struct?
1767	*/
1768	un = lookup_undo(ulp, semid);
1769	if (un) {
1770	kfree(new);
1771	goto success;
1772	}
1773	/* step 5: initialize & link new undo structure */
1774	new->semadj = (short *) &new[1];
1775	new->ulp = ulp;
1776	new->semid = semid;
1777	assert_spin_locked(&ulp->lock);
1778	list_add_rcu(&new->list_proc, &ulp->list_proc);
1779	ipc_assert_locked_object(&sma->sem_perm);
1780	list_add(&new->list_id, &sma->list_id);
1781	un = new;
1782
1783	success:
1784	spin_unlock(&ulp->lock);
1785	sem_unlock(sma, -1);
1786	out:
1787	return un;
1788	}
1789
1790
1791	/**
1792	* get_queue_result - retrieve the result code from sem_queue
1793	* @q: Pointer to queue structure
1794	*
1795	* Retrieve the return code from the pending queue. If IN_WAKEUP is found in
1796	* q->status, then we must loop until the value is replaced with the final
1797	* value: This may happen if a task is woken up by an unrelated event (e.g.
1798	* signal) and in parallel the task is woken up by another task because it got
1799	* the requested semaphores.
1800	*
1801	* The function can be called with or without holding the semaphore spinlock.
1802	*/
1803	static int get_queue_result(struct sem_queue *q)
1804	{
1805	int error;
1806
1807	error = q->status;
1808	while (unlikely(error == IN_WAKEUP)) {
1809	cpu_relax();
1810	error = q->status;
1811	}
1812
1813	return error;
1814	}
1815
1816	SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
1817	unsigned, nsops, const struct timespec __user *, timeout)
1818	{
1819	int error = -EINVAL;
1820	struct sem_array *sma;
1821	struct sembuf fast_sops[SEMOPM_FAST];
1822	struct sembuf *sops = fast_sops, *sop;
1823	struct sem_undo *un;
1824	int undos = 0, alter = 0, max, locknum;
1825	struct sem_queue queue;
1826	unsigned long jiffies_left = 0;
1827	struct ipc_namespace *ns;
1828	struct list_head tasks;
1829
1830	ns = current->nsproxy->ipc_ns;
1831
1832	if (nsops < 1 || semid < 0)
1833	return -EINVAL;
1834	if (nsops > ns->sc_semopm)
1835	return -E2BIG;
1836	if (nsops > SEMOPM_FAST) {
1837	sops = kmalloc(sizeof(*sops)*nsops, GFP_KERNEL);
1838	if (sops == NULL)
1839	return -ENOMEM;
1840	}
1841	if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
1842	error = -EFAULT;
1843	goto out_free;
1844	}
1845	if (timeout) {
1846	struct timespec _timeout;
1847	if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1848	error = -EFAULT;
1849	goto out_free;
1850	}
1851	if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1852	_timeout.tv_nsec >= 1000000000L) {
1853	error = -EINVAL;
1854	goto out_free;
1855	}
1856	jiffies_left = timespec_to_jiffies(&_timeout);
1857	}
1858	max = 0;
1859	for (sop = sops; sop < sops + nsops; sop++) {
1860	if (sop->sem_num >= max)
1861	max = sop->sem_num;
1862	if (sop->sem_flg & SEM_UNDO)
1863	undos = 1;
1864	if (sop->sem_op != 0)
1865	alter = 1;
1866	}
1867
1868	INIT_LIST_HEAD(&tasks);
1869
1870	if (undos) {
1871	/* On success, find_alloc_undo takes the rcu_read_lock */
1872	un = find_alloc_undo(ns, semid);
1873	if (IS_ERR(un)) {
1874	error = PTR_ERR(un);
1875	goto out_free;
1876	}
1877	} else {
1878	un = NULL;
1879	rcu_read_lock();
1880	}
1881
1882	sma = sem_obtain_object_check(ns, semid);
1883	if (IS_ERR(sma)) {
1884	rcu_read_unlock();
1885	error = PTR_ERR(sma);
1886	goto out_free;
1887	}
1888
1889	error = -EFBIG;
1890	if (max >= sma->sem_nsems)
1891	goto out_rcu_wakeup;
1892
1893	error = -EACCES;
1894	if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1895	goto out_rcu_wakeup;
1896
1897	error = security_sem_semop(sma, sops, nsops, alter);
1898	if (error)
1899	goto out_rcu_wakeup;
1900
1901	error = -EIDRM;
1902	locknum = sem_lock(sma, sops, nsops);
1903	/*
1904	* We eventually might perform the following check in a lockless
1905	* fashion, considering ipc_valid_object() locking constraints.
1906	* If nsops == 1 and there is no contention for sem_perm.lock, then
1907	* only a per-semaphore lock is held and it's OK to proceed with the
1908	* check below. More details on the fine grained locking scheme
1909	* entangled here and why it's RMID race safe on comments at sem_lock()
1910	*/
1911	if (!ipc_valid_object(&sma->sem_perm))
1912	goto out_unlock_free;
1913	/*
1914	* semid identifiers are not unique - find_alloc_undo may have
1915	* allocated an undo structure, it was invalidated by an RMID
1916	* and now a new array with received the same id. Check and fail.
1917	* This case can be detected checking un->semid. The existence of
1918	* "un" itself is guaranteed by rcu.
1919	*/
1920	if (un && un->semid == -1)
1921	goto out_unlock_free;
1922
1923	queue.sops = sops;
1924	queue.nsops = nsops;
1925	queue.undo = un;
1926	queue.pid = task_tgid_vnr(current);
1927	queue.alter = alter;
1928
1929	error = perform_atomic_semop(sma, &queue);
1930	if (error == 0) {
1931	/* If the operation was successful, then do
1932	* the required updates.
1933	*/
1934	if (alter)
1935	do_smart_update(sma, sops, nsops, 1, &tasks);
1936	else
1937	set_semotime(sma, sops);
1938	}
1939	if (error <= 0)
1940	goto out_unlock_free;
1941
1942	/* We need to sleep on this operation, so we put the current
1943	* task into the pending queue and go to sleep.
1944	*/
1945
1946	if (nsops == 1) {
1947	struct sem *curr;
1948	curr = &sma->sem_base[sops->sem_num];
1949
1950	if (alter) {
1951	if (sma->complex_count) {
1952	list_add_tail(&queue.list,
1953	&sma->pending_alter);
1954	} else {
1955
1956	list_add_tail(&queue.list,
1957	&curr->pending_alter);
1958	}
1959	} else {
1960	list_add_tail(&queue.list, &curr->pending_const);
1961	}
1962	} else {
1963	if (!sma->complex_count)
1964	merge_queues(sma);
1965
1966	if (alter)
1967	list_add_tail(&queue.list, &sma->pending_alter);
1968	else
1969	list_add_tail(&queue.list, &sma->pending_const);
1970
1971	sma->complex_count++;
1972	}
1973
1974	queue.status = -EINTR;
1975	queue.sleeper = current;
1976
1977	sleep_again:
1978	__set_current_state(TASK_INTERRUPTIBLE);
1979	sem_unlock(sma, locknum);
1980	rcu_read_unlock();
1981
1982	if (timeout)
1983	jiffies_left = schedule_timeout(jiffies_left);
1984	else
1985	schedule();
1986
1987	error = get_queue_result(&queue);
1988
1989	if (error != -EINTR) {
1990	/* fast path: update_queue already obtained all requested
1991	* resources.
1992	* Perform a smp_mb(): User space could assume that semop()
1993	* is a memory barrier: Without the mb(), the cpu could
1994	* speculatively read in user space stale data that was
1995	* overwritten by the previous owner of the semaphore.
1996	*/
1997	smp_mb();
1998
1999	goto out_free;
2000	}
2001
2002	rcu_read_lock();
2003	sma = sem_obtain_lock(ns, semid, sops, nsops, &locknum);
2004
2005	/*
2006	* Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing.
2007	*/
2008	error = get_queue_result(&queue);
2009
2010	/*
2011	* Array removed? If yes, leave without sem_unlock().
2012	*/
2013	if (IS_ERR(sma)) {
2014	rcu_read_unlock();
2015	goto out_free;
2016	}
2017
2018
2019	/*
2020	* If queue.status != -EINTR we are woken up by another process.
2021	* Leave without unlink_queue(), but with sem_unlock().
2022	*/
2023	if (error != -EINTR)
2024	goto out_unlock_free;
2025
2026	/*
2027	* If an interrupt occurred we have to clean up the queue
2028	*/
2029	if (timeout && jiffies_left == 0)
2030	error = -EAGAIN;
2031
2032	/*
2033	* If the wakeup was spurious, just retry
2034	*/
2035	if (error == -EINTR && !signal_pending(current))
2036	goto sleep_again;
2037
2038	unlink_queue(sma, &queue);
2039
2040	out_unlock_free:
2041	sem_unlock(sma, locknum);
2042	out_rcu_wakeup:
2043	rcu_read_unlock();
2044	wake_up_sem_queue_do(&tasks);
2045	out_free:
2046	if (sops != fast_sops)
2047	kfree(sops);
2048	return error;
2049	}
2050
2051	SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
2052	unsigned, nsops)
2053	{
2054	return sys_semtimedop(semid, tsops, nsops, NULL);
2055	}
2056
2057	/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
2058	* parent and child tasks.
2059	*/
2060
2061	int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
2062	{
2063	struct sem_undo_list *undo_list;
2064	int error;
2065
2066	if (clone_flags & CLONE_SYSVSEM) {
2067	error = get_undo_list(&undo_list);
2068	if (error)
2069	return error;
2070	atomic_inc(&undo_list->refcnt);
2071	tsk->sysvsem.undo_list = undo_list;
2072	} else
2073	tsk->sysvsem.undo_list = NULL;
2074
2075	return 0;
2076	}
2077
2078	/*
2079	* add semadj values to semaphores, free undo structures.
2080	* undo structures are not freed when semaphore arrays are destroyed
2081	* so some of them may be out of date.
2082	* IMPLEMENTATION NOTE: There is some confusion over whether the
2083	* set of adjustments that needs to be done should be done in an atomic
2084	* manner or not. That is, if we are attempting to decrement the semval
2085	* should we queue up and wait until we can do so legally?
2086	* The original implementation attempted to do this (queue and wait).
2087	* The current implementation does not do so. The POSIX standard
2088	* and SVID should be consulted to determine what behavior is mandated.
2089	*/
2090	void exit_sem(struct task_struct *tsk)
2091	{
2092	struct sem_undo_list *ulp;
2093
2094	ulp = tsk->sysvsem.undo_list;
2095	if (!ulp)
2096	return;
2097	tsk->sysvsem.undo_list = NULL;
2098
2099	if (!atomic_dec_and_test(&ulp->refcnt))
2100	return;
2101
2102	for (;;) {
2103	struct sem_array *sma;
2104	struct sem_undo *un;
2105	struct list_head tasks;
2106	int semid, i;
2107
2108	cond_resched();
2109
2110	rcu_read_lock();
2111	un = list_entry_rcu(ulp->list_proc.next,
2112	struct sem_undo, list_proc);
2113	if (&un->list_proc == &ulp->list_proc) {
2114	/*
2115	* We must wait for freeary() before freeing this ulp,
2116	* in case we raced with last sem_undo. There is a small
2117	* possibility where we exit while freeary() didn't
2118	* finish unlocking sem_undo_list.
2119	*/
2120	spin_unlock_wait(&ulp->lock);
2121	rcu_read_unlock();
2122	break;
2123	}
2124	spin_lock(&ulp->lock);
2125	semid = un->semid;
2126	spin_unlock(&ulp->lock);
2127
2128	/* exit_sem raced with IPC_RMID, nothing to do */
2129	if (semid == -1) {
2130	rcu_read_unlock();
2131	continue;
2132	}
2133
2134	sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, semid);
2135	/* exit_sem raced with IPC_RMID, nothing to do */
2136	if (IS_ERR(sma)) {
2137	rcu_read_unlock();
2138	continue;
2139	}
2140
2141	sem_lock(sma, NULL, -1);
2142	/* exit_sem raced with IPC_RMID, nothing to do */
2143	if (!ipc_valid_object(&sma->sem_perm)) {
2144	sem_unlock(sma, -1);
2145	rcu_read_unlock();
2146	continue;
2147	}
2148	un = __lookup_undo(ulp, semid);
2149	if (un == NULL) {
2150	/* exit_sem raced with IPC_RMID+semget() that created
2151	* exactly the same semid. Nothing to do.
2152	*/
2153	sem_unlock(sma, -1);
2154	rcu_read_unlock();
2155	continue;
2156	}
2157
2158	/* remove un from the linked lists */
2159	ipc_assert_locked_object(&sma->sem_perm);
2160	list_del(&un->list_id);
2161
2162	/* we are the last process using this ulp, acquiring ulp->lock
2163	* isn't required. Besides that, we are also protected against
2164	* IPC_RMID as we hold sma->sem_perm lock now
2165	*/
2166	list_del_rcu(&un->list_proc);
2167
2168	/* perform adjustments registered in un */
2169	for (i = 0; i < sma->sem_nsems; i++) {
2170	struct sem *semaphore = &sma->sem_base[i];
2171	if (un->semadj[i]) {
2172	semaphore->semval += un->semadj[i];
2173	/*
2174	* Range checks of the new semaphore value,
2175	* not defined by sus:
2176	* - Some unices ignore the undo entirely
2177	* (e.g. HP UX 11i 11.22, Tru64 V5.1)
2178	* - some cap the value (e.g. FreeBSD caps
2179	* at 0, but doesn't enforce SEMVMX)
2180	*
2181	* Linux caps the semaphore value, both at 0
2182	* and at SEMVMX.
2183	*
2184	* Manfred <manfred@colorfullife.com>
2185	*/
2186	if (semaphore->semval < 0)
2187	semaphore->semval = 0;
2188	if (semaphore->semval > SEMVMX)
2189	semaphore->semval = SEMVMX;
2190	semaphore->sempid = task_tgid_vnr(current);
2191	}
2192	}
2193	/* maybe some queued-up processes were waiting for this */
2194	INIT_LIST_HEAD(&tasks);
2195	do_smart_update(sma, NULL, 0, 1, &tasks);
2196	sem_unlock(sma, -1);
2197	rcu_read_unlock();
2198	wake_up_sem_queue_do(&tasks);
2199
2200	kfree_rcu(un, rcu);
2201	}
2202	kfree(ulp);
2203	}
2204
2205	#ifdef CONFIG_PROC_FS
2206	static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
2207	{
2208	struct user_namespace *user_ns = seq_user_ns(s);
2209	struct sem_array *sma = it;
2210	time_t sem_otime;
2211
2212	/*
2213	* The proc interface isn't aware of sem_lock(), it calls
2214	* ipc_lock_object() directly (in sysvipc_find_ipc).
2215	* In order to stay compatible with sem_lock(), we must
2216	* enter / leave complex_mode.
2217	*/
2218	complexmode_enter(sma);
2219
2220	sem_otime = get_semotime(sma);
2221
2222	seq_printf(s,
2223	"%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
2224	sma->sem_perm.key,
2225	sma->sem_perm.id,
2226	sma->sem_perm.mode,
2227	sma->sem_nsems,
2228	from_kuid_munged(user_ns, sma->sem_perm.uid),
2229	from_kgid_munged(user_ns, sma->sem_perm.gid),
2230	from_kuid_munged(user_ns, sma->sem_perm.cuid),
2231	from_kgid_munged(user_ns, sma->sem_perm.cgid),
2232	sem_otime,
2233	sma->sem_ctime);
2234
2235	complexmode_tryleave(sma);
2236
2237	return 0;
2238	}
2239	#endif
2240