xref: /openbmc/linux/ipc/sem.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * linux/ipc/sem.c
3  * Copyright (C) 1992 Krishna Balasubramanian
4  * Copyright (C) 1995 Eric Schenk, Bruno Haible
5  *
6  * IMPLEMENTATION NOTES ON CODE REWRITE (Eric Schenk, January 1995):
7  * This code underwent a massive rewrite in order to solve some problems
8  * with the original code. In particular the original code failed to
9  * wake up processes that were waiting for semval to go to 0 if the
10  * value went to 0 and was then incremented rapidly enough. In solving
11  * this problem I have also modified the implementation so that it
12  * processes pending operations in a FIFO manner, thus give a guarantee
13  * that processes waiting for a lock on the semaphore won't starve
14  * unless another locking process fails to unlock.
15  * In addition the following two changes in behavior have been introduced:
16  * - The original implementation of semop returned the value
17  *   last semaphore element examined on success. This does not
18  *   match the manual page specifications, and effectively
19  *   allows the user to read the semaphore even if they do not
20  *   have read permissions. The implementation now returns 0
21  *   on success as stated in the manual page.
22  * - There is some confusion over whether the set of undo adjustments
23  *   to be performed at exit should be done in an atomic manner.
24  *   That is, if we are attempting to decrement the semval should we queue
25  *   up and wait until we can do so legally?
26  *   The original implementation attempted to do this.
27  *   The current implementation does not do so. This is because I don't
28  *   think it is the right thing (TM) to do, and because I couldn't
29  *   see a clean way to get the old behavior with the new design.
30  *   The POSIX standard and SVID should be consulted to determine
31  *   what behavior is mandated.
32  *
33  * Further notes on refinement (Christoph Rohland, December 1998):
34  * - The POSIX standard says, that the undo adjustments simply should
35  *   redo. So the current implementation is o.K.
36  * - The previous code had two flaws:
37  *   1) It actively gave the semaphore to the next waiting process
38  *      sleeping on the semaphore. Since this process did not have the
39  *      cpu this led to many unnecessary context switches and bad
40  *      performance. Now we only check which process should be able to
41  *      get the semaphore and if this process wants to reduce some
42  *      semaphore value we simply wake it up without doing the
43  *      operation. So it has to try to get it later. Thus e.g. the
44  *      running process may reacquire the semaphore during the current
45  *      time slice. If it only waits for zero or increases the semaphore,
46  *      we do the operation in advance and wake it up.
47  *   2) It did not wake up all zero waiting processes. We try to do
48  *      better but only get the semops right which only wait for zero or
49  *      increase. If there are decrement operations in the operations
50  *      array we do the same as before.
51  *
52  * With the incarnation of O(1) scheduler, it becomes unnecessary to perform
53  * check/retry algorithm for waking up blocked processes as the new scheduler
54  * is better at handling thread switch than the old one.
55  *
56  * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
57  *
58  * SMP-threaded, sysctl's added
59  * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
60  * Enforced range limit on SEM_UNDO
61  * (c) 2001 Red Hat Inc <alan@redhat.com>
62  * Lockless wakeup
63  * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
64  *
65  * support for audit of ipc object properties and permission changes
66  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
67  *
68  * namespaces support
69  * OpenVZ, SWsoft Inc.
70  * Pavel Emelianov <xemul@openvz.org>
71  */
72 
73 #include <linux/slab.h>
74 #include <linux/spinlock.h>
75 #include <linux/init.h>
76 #include <linux/proc_fs.h>
77 #include <linux/time.h>
78 #include <linux/security.h>
79 #include <linux/syscalls.h>
80 #include <linux/audit.h>
81 #include <linux/capability.h>
82 #include <linux/seq_file.h>
83 #include <linux/mutex.h>
84 #include <linux/nsproxy.h>
85 
86 #include <asm/uaccess.h>
87 #include "util.h"
88 
89 #define sem_ids(ns)	(*((ns)->ids[IPC_SEM_IDS]))
90 
91 #define sem_lock(ns, id)	((struct sem_array*)ipc_lock(&sem_ids(ns), id))
92 #define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
93 #define sem_rmid(ns, id)	((struct sem_array*)ipc_rmid(&sem_ids(ns), id))
94 #define sem_checkid(ns, sma, semid)	\
95 	ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
96 #define sem_buildid(ns, id, seq) \
97 	ipc_buildid(&sem_ids(ns), id, seq)
98 
99 static struct ipc_ids init_sem_ids;
100 
101 static int newary(struct ipc_namespace *, key_t, int, int);
102 static void freeary(struct ipc_namespace *ns, struct sem_array *sma, int id);
103 #ifdef CONFIG_PROC_FS
104 static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
105 #endif
106 
107 #define SEMMSL_FAST	256 /* 512 bytes on stack */
108 #define SEMOPM_FAST	64  /* ~ 372 bytes on stack */
109 
110 /*
111  * linked list protection:
112  *	sem_undo.id_next,
113  *	sem_array.sem_pending{,last},
114  *	sem_array.sem_undo: sem_lock() for read/write
115  *	sem_undo.proc_next: only "current" is allowed to read/write that field.
116  *
117  */
118 
119 #define sc_semmsl	sem_ctls[0]
120 #define sc_semmns	sem_ctls[1]
121 #define sc_semopm	sem_ctls[2]
122 #define sc_semmni	sem_ctls[3]
123 
124 static void __ipc_init __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
125 {
126 	ns->ids[IPC_SEM_IDS] = ids;
127 	ns->sc_semmsl = SEMMSL;
128 	ns->sc_semmns = SEMMNS;
129 	ns->sc_semopm = SEMOPM;
130 	ns->sc_semmni = SEMMNI;
131 	ns->used_sems = 0;
132 	ipc_init_ids(ids, ns->sc_semmni);
133 }
134 
135 #ifdef CONFIG_IPC_NS
136 int sem_init_ns(struct ipc_namespace *ns)
137 {
138 	struct ipc_ids *ids;
139 
140 	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
141 	if (ids == NULL)
142 		return -ENOMEM;
143 
144 	__sem_init_ns(ns, ids);
145 	return 0;
146 }
147 
148 void sem_exit_ns(struct ipc_namespace *ns)
149 {
150 	int i;
151 	struct sem_array *sma;
152 
153 	mutex_lock(&sem_ids(ns).mutex);
154 	for (i = 0; i <= sem_ids(ns).max_id; i++) {
155 		sma = sem_lock(ns, i);
156 		if (sma == NULL)
157 			continue;
158 
159 		freeary(ns, sma, i);
160 	}
161 	mutex_unlock(&sem_ids(ns).mutex);
162 
163 	ipc_fini_ids(ns->ids[IPC_SEM_IDS]);
164 	kfree(ns->ids[IPC_SEM_IDS]);
165 	ns->ids[IPC_SEM_IDS] = NULL;
166 }
167 #endif
168 
169 void __init sem_init (void)
170 {
171 	__sem_init_ns(&init_ipc_ns, &init_sem_ids);
172 	ipc_init_proc_interface("sysvipc/sem",
173 				"       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n",
174 				IPC_SEM_IDS, sysvipc_sem_proc_show);
175 }
176 
177 /*
178  * Lockless wakeup algorithm:
179  * Without the check/retry algorithm a lockless wakeup is possible:
180  * - queue.status is initialized to -EINTR before blocking.
181  * - wakeup is performed by
182  *	* unlinking the queue entry from sma->sem_pending
183  *	* setting queue.status to IN_WAKEUP
184  *	  This is the notification for the blocked thread that a
185  *	  result value is imminent.
186  *	* call wake_up_process
187  *	* set queue.status to the final value.
188  * - the previously blocked thread checks queue.status:
189  *   	* if it's IN_WAKEUP, then it must wait until the value changes
190  *   	* if it's not -EINTR, then the operation was completed by
191  *   	  update_queue. semtimedop can return queue.status without
192  *   	  performing any operation on the sem array.
193  *   	* otherwise it must acquire the spinlock and check what's up.
194  *
195  * The two-stage algorithm is necessary to protect against the following
196  * races:
197  * - if queue.status is set after wake_up_process, then the woken up idle
198  *   thread could race forward and try (and fail) to acquire sma->lock
199  *   before update_queue had a chance to set queue.status
200  * - if queue.status is written before wake_up_process and if the
201  *   blocked process is woken up by a signal between writing
202  *   queue.status and the wake_up_process, then the woken up
203  *   process could return from semtimedop and die by calling
204  *   sys_exit before wake_up_process is called. Then wake_up_process
205  *   will oops, because the task structure is already invalid.
206  *   (yes, this happened on s390 with sysv msg).
207  *
208  */
209 #define IN_WAKEUP	1
210 
211 static int newary (struct ipc_namespace *ns, key_t key, int nsems, int semflg)
212 {
213 	int id;
214 	int retval;
215 	struct sem_array *sma;
216 	int size;
217 
218 	if (!nsems)
219 		return -EINVAL;
220 	if (ns->used_sems + nsems > ns->sc_semmns)
221 		return -ENOSPC;
222 
223 	size = sizeof (*sma) + nsems * sizeof (struct sem);
224 	sma = ipc_rcu_alloc(size);
225 	if (!sma) {
226 		return -ENOMEM;
227 	}
228 	memset (sma, 0, size);
229 
230 	sma->sem_perm.mode = (semflg & S_IRWXUGO);
231 	sma->sem_perm.key = key;
232 
233 	sma->sem_perm.security = NULL;
234 	retval = security_sem_alloc(sma);
235 	if (retval) {
236 		ipc_rcu_putref(sma);
237 		return retval;
238 	}
239 
240 	id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
241 	if(id == -1) {
242 		security_sem_free(sma);
243 		ipc_rcu_putref(sma);
244 		return -ENOSPC;
245 	}
246 	ns->used_sems += nsems;
247 
248 	sma->sem_id = sem_buildid(ns, id, sma->sem_perm.seq);
249 	sma->sem_base = (struct sem *) &sma[1];
250 	/* sma->sem_pending = NULL; */
251 	sma->sem_pending_last = &sma->sem_pending;
252 	/* sma->undo = NULL; */
253 	sma->sem_nsems = nsems;
254 	sma->sem_ctime = get_seconds();
255 	sem_unlock(sma);
256 
257 	return sma->sem_id;
258 }
259 
260 asmlinkage long sys_semget (key_t key, int nsems, int semflg)
261 {
262 	int id, err = -EINVAL;
263 	struct sem_array *sma;
264 	struct ipc_namespace *ns;
265 
266 	ns = current->nsproxy->ipc_ns;
267 
268 	if (nsems < 0 || nsems > ns->sc_semmsl)
269 		return -EINVAL;
270 	mutex_lock(&sem_ids(ns).mutex);
271 
272 	if (key == IPC_PRIVATE) {
273 		err = newary(ns, key, nsems, semflg);
274 	} else if ((id = ipc_findkey(&sem_ids(ns), key)) == -1) {  /* key not used */
275 		if (!(semflg & IPC_CREAT))
276 			err = -ENOENT;
277 		else
278 			err = newary(ns, key, nsems, semflg);
279 	} else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
280 		err = -EEXIST;
281 	} else {
282 		sma = sem_lock(ns, id);
283 		BUG_ON(sma==NULL);
284 		if (nsems > sma->sem_nsems)
285 			err = -EINVAL;
286 		else if (ipcperms(&sma->sem_perm, semflg))
287 			err = -EACCES;
288 		else {
289 			int semid = sem_buildid(ns, id, sma->sem_perm.seq);
290 			err = security_sem_associate(sma, semflg);
291 			if (!err)
292 				err = semid;
293 		}
294 		sem_unlock(sma);
295 	}
296 
297 	mutex_unlock(&sem_ids(ns).mutex);
298 	return err;
299 }
300 
301 /* Manage the doubly linked list sma->sem_pending as a FIFO:
302  * insert new queue elements at the tail sma->sem_pending_last.
303  */
304 static inline void append_to_queue (struct sem_array * sma,
305 				    struct sem_queue * q)
306 {
307 	*(q->prev = sma->sem_pending_last) = q;
308 	*(sma->sem_pending_last = &q->next) = NULL;
309 }
310 
311 static inline void prepend_to_queue (struct sem_array * sma,
312 				     struct sem_queue * q)
313 {
314 	q->next = sma->sem_pending;
315 	*(q->prev = &sma->sem_pending) = q;
316 	if (q->next)
317 		q->next->prev = &q->next;
318 	else /* sma->sem_pending_last == &sma->sem_pending */
319 		sma->sem_pending_last = &q->next;
320 }
321 
322 static inline void remove_from_queue (struct sem_array * sma,
323 				      struct sem_queue * q)
324 {
325 	*(q->prev) = q->next;
326 	if (q->next)
327 		q->next->prev = q->prev;
328 	else /* sma->sem_pending_last == &q->next */
329 		sma->sem_pending_last = q->prev;
330 	q->prev = NULL; /* mark as removed */
331 }
332 
333 /*
334  * Determine whether a sequence of semaphore operations would succeed
335  * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
336  */
337 
338 static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
339 			     int nsops, struct sem_undo *un, int pid)
340 {
341 	int result, sem_op;
342 	struct sembuf *sop;
343 	struct sem * curr;
344 
345 	for (sop = sops; sop < sops + nsops; sop++) {
346 		curr = sma->sem_base + sop->sem_num;
347 		sem_op = sop->sem_op;
348 		result = curr->semval;
349 
350 		if (!sem_op && result)
351 			goto would_block;
352 
353 		result += sem_op;
354 		if (result < 0)
355 			goto would_block;
356 		if (result > SEMVMX)
357 			goto out_of_range;
358 		if (sop->sem_flg & SEM_UNDO) {
359 			int undo = un->semadj[sop->sem_num] - sem_op;
360 			/*
361 	 		 *	Exceeding the undo range is an error.
362 			 */
363 			if (undo < (-SEMAEM - 1) || undo > SEMAEM)
364 				goto out_of_range;
365 		}
366 		curr->semval = result;
367 	}
368 
369 	sop--;
370 	while (sop >= sops) {
371 		sma->sem_base[sop->sem_num].sempid = pid;
372 		if (sop->sem_flg & SEM_UNDO)
373 			un->semadj[sop->sem_num] -= sop->sem_op;
374 		sop--;
375 	}
376 
377 	sma->sem_otime = get_seconds();
378 	return 0;
379 
380 out_of_range:
381 	result = -ERANGE;
382 	goto undo;
383 
384 would_block:
385 	if (sop->sem_flg & IPC_NOWAIT)
386 		result = -EAGAIN;
387 	else
388 		result = 1;
389 
390 undo:
391 	sop--;
392 	while (sop >= sops) {
393 		sma->sem_base[sop->sem_num].semval -= sop->sem_op;
394 		sop--;
395 	}
396 
397 	return result;
398 }
399 
400 /* Go through the pending queue for the indicated semaphore
401  * looking for tasks that can be completed.
402  */
403 static void update_queue (struct sem_array * sma)
404 {
405 	int error;
406 	struct sem_queue * q;
407 
408 	q = sma->sem_pending;
409 	while(q) {
410 		error = try_atomic_semop(sma, q->sops, q->nsops,
411 					 q->undo, q->pid);
412 
413 		/* Does q->sleeper still need to sleep? */
414 		if (error <= 0) {
415 			struct sem_queue *n;
416 			remove_from_queue(sma,q);
417 			q->status = IN_WAKEUP;
418 			/*
419 			 * Continue scanning. The next operation
420 			 * that must be checked depends on the type of the
421 			 * completed operation:
422 			 * - if the operation modified the array, then
423 			 *   restart from the head of the queue and
424 			 *   check for threads that might be waiting
425 			 *   for semaphore values to become 0.
426 			 * - if the operation didn't modify the array,
427 			 *   then just continue.
428 			 */
429 			if (q->alter)
430 				n = sma->sem_pending;
431 			else
432 				n = q->next;
433 			wake_up_process(q->sleeper);
434 			/* hands-off: q will disappear immediately after
435 			 * writing q->status.
436 			 */
437 			smp_wmb();
438 			q->status = error;
439 			q = n;
440 		} else {
441 			q = q->next;
442 		}
443 	}
444 }
445 
446 /* The following counts are associated to each semaphore:
447  *   semncnt        number of tasks waiting on semval being nonzero
448  *   semzcnt        number of tasks waiting on semval being zero
449  * This model assumes that a task waits on exactly one semaphore.
450  * Since semaphore operations are to be performed atomically, tasks actually
451  * wait on a whole sequence of semaphores simultaneously.
452  * The counts we return here are a rough approximation, but still
453  * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
454  */
455 static int count_semncnt (struct sem_array * sma, ushort semnum)
456 {
457 	int semncnt;
458 	struct sem_queue * q;
459 
460 	semncnt = 0;
461 	for (q = sma->sem_pending; q; q = q->next) {
462 		struct sembuf * sops = q->sops;
463 		int nsops = q->nsops;
464 		int i;
465 		for (i = 0; i < nsops; i++)
466 			if (sops[i].sem_num == semnum
467 			    && (sops[i].sem_op < 0)
468 			    && !(sops[i].sem_flg & IPC_NOWAIT))
469 				semncnt++;
470 	}
471 	return semncnt;
472 }
473 static int count_semzcnt (struct sem_array * sma, ushort semnum)
474 {
475 	int semzcnt;
476 	struct sem_queue * q;
477 
478 	semzcnt = 0;
479 	for (q = sma->sem_pending; q; q = q->next) {
480 		struct sembuf * sops = q->sops;
481 		int nsops = q->nsops;
482 		int i;
483 		for (i = 0; i < nsops; i++)
484 			if (sops[i].sem_num == semnum
485 			    && (sops[i].sem_op == 0)
486 			    && !(sops[i].sem_flg & IPC_NOWAIT))
487 				semzcnt++;
488 	}
489 	return semzcnt;
490 }
491 
492 /* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
493  * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
494  * on exit.
495  */
496 static void freeary (struct ipc_namespace *ns, struct sem_array *sma, int id)
497 {
498 	struct sem_undo *un;
499 	struct sem_queue *q;
500 	int size;
501 
502 	/* Invalidate the existing undo structures for this semaphore set.
503 	 * (They will be freed without any further action in exit_sem()
504 	 * or during the next semop.)
505 	 */
506 	for (un = sma->undo; un; un = un->id_next)
507 		un->semid = -1;
508 
509 	/* Wake up all pending processes and let them fail with EIDRM. */
510 	q = sma->sem_pending;
511 	while(q) {
512 		struct sem_queue *n;
513 		/* lazy remove_from_queue: we are killing the whole queue */
514 		q->prev = NULL;
515 		n = q->next;
516 		q->status = IN_WAKEUP;
517 		wake_up_process(q->sleeper); /* doesn't sleep */
518 		smp_wmb();
519 		q->status = -EIDRM;	/* hands-off q */
520 		q = n;
521 	}
522 
523 	/* Remove the semaphore set from the ID array*/
524 	sma = sem_rmid(ns, id);
525 	sem_unlock(sma);
526 
527 	ns->used_sems -= sma->sem_nsems;
528 	size = sizeof (*sma) + sma->sem_nsems * sizeof (struct sem);
529 	security_sem_free(sma);
530 	ipc_rcu_putref(sma);
531 }
532 
533 static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
534 {
535 	switch(version) {
536 	case IPC_64:
537 		return copy_to_user(buf, in, sizeof(*in));
538 	case IPC_OLD:
539 	    {
540 		struct semid_ds out;
541 
542 		ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
543 
544 		out.sem_otime	= in->sem_otime;
545 		out.sem_ctime	= in->sem_ctime;
546 		out.sem_nsems	= in->sem_nsems;
547 
548 		return copy_to_user(buf, &out, sizeof(out));
549 	    }
550 	default:
551 		return -EINVAL;
552 	}
553 }
554 
555 static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
556 		int cmd, int version, union semun arg)
557 {
558 	int err = -EINVAL;
559 	struct sem_array *sma;
560 
561 	switch(cmd) {
562 	case IPC_INFO:
563 	case SEM_INFO:
564 	{
565 		struct seminfo seminfo;
566 		int max_id;
567 
568 		err = security_sem_semctl(NULL, cmd);
569 		if (err)
570 			return err;
571 
572 		memset(&seminfo,0,sizeof(seminfo));
573 		seminfo.semmni = ns->sc_semmni;
574 		seminfo.semmns = ns->sc_semmns;
575 		seminfo.semmsl = ns->sc_semmsl;
576 		seminfo.semopm = ns->sc_semopm;
577 		seminfo.semvmx = SEMVMX;
578 		seminfo.semmnu = SEMMNU;
579 		seminfo.semmap = SEMMAP;
580 		seminfo.semume = SEMUME;
581 		mutex_lock(&sem_ids(ns).mutex);
582 		if (cmd == SEM_INFO) {
583 			seminfo.semusz = sem_ids(ns).in_use;
584 			seminfo.semaem = ns->used_sems;
585 		} else {
586 			seminfo.semusz = SEMUSZ;
587 			seminfo.semaem = SEMAEM;
588 		}
589 		max_id = sem_ids(ns).max_id;
590 		mutex_unlock(&sem_ids(ns).mutex);
591 		if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
592 			return -EFAULT;
593 		return (max_id < 0) ? 0: max_id;
594 	}
595 	case SEM_STAT:
596 	{
597 		struct semid64_ds tbuf;
598 		int id;
599 
600 		if(semid >= sem_ids(ns).entries->size)
601 			return -EINVAL;
602 
603 		memset(&tbuf,0,sizeof(tbuf));
604 
605 		sma = sem_lock(ns, semid);
606 		if(sma == NULL)
607 			return -EINVAL;
608 
609 		err = -EACCES;
610 		if (ipcperms (&sma->sem_perm, S_IRUGO))
611 			goto out_unlock;
612 
613 		err = security_sem_semctl(sma, cmd);
614 		if (err)
615 			goto out_unlock;
616 
617 		id = sem_buildid(ns, semid, sma->sem_perm.seq);
618 
619 		kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
620 		tbuf.sem_otime  = sma->sem_otime;
621 		tbuf.sem_ctime  = sma->sem_ctime;
622 		tbuf.sem_nsems  = sma->sem_nsems;
623 		sem_unlock(sma);
624 		if (copy_semid_to_user (arg.buf, &tbuf, version))
625 			return -EFAULT;
626 		return id;
627 	}
628 	default:
629 		return -EINVAL;
630 	}
631 	return err;
632 out_unlock:
633 	sem_unlock(sma);
634 	return err;
635 }
636 
637 static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
638 		int cmd, int version, union semun arg)
639 {
640 	struct sem_array *sma;
641 	struct sem* curr;
642 	int err;
643 	ushort fast_sem_io[SEMMSL_FAST];
644 	ushort* sem_io = fast_sem_io;
645 	int nsems;
646 
647 	sma = sem_lock(ns, semid);
648 	if(sma==NULL)
649 		return -EINVAL;
650 
651 	nsems = sma->sem_nsems;
652 
653 	err=-EIDRM;
654 	if (sem_checkid(ns,sma,semid))
655 		goto out_unlock;
656 
657 	err = -EACCES;
658 	if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
659 		goto out_unlock;
660 
661 	err = security_sem_semctl(sma, cmd);
662 	if (err)
663 		goto out_unlock;
664 
665 	err = -EACCES;
666 	switch (cmd) {
667 	case GETALL:
668 	{
669 		ushort __user *array = arg.array;
670 		int i;
671 
672 		if(nsems > SEMMSL_FAST) {
673 			ipc_rcu_getref(sma);
674 			sem_unlock(sma);
675 
676 			sem_io = ipc_alloc(sizeof(ushort)*nsems);
677 			if(sem_io == NULL) {
678 				ipc_lock_by_ptr(&sma->sem_perm);
679 				ipc_rcu_putref(sma);
680 				sem_unlock(sma);
681 				return -ENOMEM;
682 			}
683 
684 			ipc_lock_by_ptr(&sma->sem_perm);
685 			ipc_rcu_putref(sma);
686 			if (sma->sem_perm.deleted) {
687 				sem_unlock(sma);
688 				err = -EIDRM;
689 				goto out_free;
690 			}
691 		}
692 
693 		for (i = 0; i < sma->sem_nsems; i++)
694 			sem_io[i] = sma->sem_base[i].semval;
695 		sem_unlock(sma);
696 		err = 0;
697 		if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
698 			err = -EFAULT;
699 		goto out_free;
700 	}
701 	case SETALL:
702 	{
703 		int i;
704 		struct sem_undo *un;
705 
706 		ipc_rcu_getref(sma);
707 		sem_unlock(sma);
708 
709 		if(nsems > SEMMSL_FAST) {
710 			sem_io = ipc_alloc(sizeof(ushort)*nsems);
711 			if(sem_io == NULL) {
712 				ipc_lock_by_ptr(&sma->sem_perm);
713 				ipc_rcu_putref(sma);
714 				sem_unlock(sma);
715 				return -ENOMEM;
716 			}
717 		}
718 
719 		if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
720 			ipc_lock_by_ptr(&sma->sem_perm);
721 			ipc_rcu_putref(sma);
722 			sem_unlock(sma);
723 			err = -EFAULT;
724 			goto out_free;
725 		}
726 
727 		for (i = 0; i < nsems; i++) {
728 			if (sem_io[i] > SEMVMX) {
729 				ipc_lock_by_ptr(&sma->sem_perm);
730 				ipc_rcu_putref(sma);
731 				sem_unlock(sma);
732 				err = -ERANGE;
733 				goto out_free;
734 			}
735 		}
736 		ipc_lock_by_ptr(&sma->sem_perm);
737 		ipc_rcu_putref(sma);
738 		if (sma->sem_perm.deleted) {
739 			sem_unlock(sma);
740 			err = -EIDRM;
741 			goto out_free;
742 		}
743 
744 		for (i = 0; i < nsems; i++)
745 			sma->sem_base[i].semval = sem_io[i];
746 		for (un = sma->undo; un; un = un->id_next)
747 			for (i = 0; i < nsems; i++)
748 				un->semadj[i] = 0;
749 		sma->sem_ctime = get_seconds();
750 		/* maybe some queued-up processes were waiting for this */
751 		update_queue(sma);
752 		err = 0;
753 		goto out_unlock;
754 	}
755 	case IPC_STAT:
756 	{
757 		struct semid64_ds tbuf;
758 		memset(&tbuf,0,sizeof(tbuf));
759 		kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
760 		tbuf.sem_otime  = sma->sem_otime;
761 		tbuf.sem_ctime  = sma->sem_ctime;
762 		tbuf.sem_nsems  = sma->sem_nsems;
763 		sem_unlock(sma);
764 		if (copy_semid_to_user (arg.buf, &tbuf, version))
765 			return -EFAULT;
766 		return 0;
767 	}
768 	/* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
769 	}
770 	err = -EINVAL;
771 	if(semnum < 0 || semnum >= nsems)
772 		goto out_unlock;
773 
774 	curr = &sma->sem_base[semnum];
775 
776 	switch (cmd) {
777 	case GETVAL:
778 		err = curr->semval;
779 		goto out_unlock;
780 	case GETPID:
781 		err = curr->sempid;
782 		goto out_unlock;
783 	case GETNCNT:
784 		err = count_semncnt(sma,semnum);
785 		goto out_unlock;
786 	case GETZCNT:
787 		err = count_semzcnt(sma,semnum);
788 		goto out_unlock;
789 	case SETVAL:
790 	{
791 		int val = arg.val;
792 		struct sem_undo *un;
793 		err = -ERANGE;
794 		if (val > SEMVMX || val < 0)
795 			goto out_unlock;
796 
797 		for (un = sma->undo; un; un = un->id_next)
798 			un->semadj[semnum] = 0;
799 		curr->semval = val;
800 		curr->sempid = current->tgid;
801 		sma->sem_ctime = get_seconds();
802 		/* maybe some queued-up processes were waiting for this */
803 		update_queue(sma);
804 		err = 0;
805 		goto out_unlock;
806 	}
807 	}
808 out_unlock:
809 	sem_unlock(sma);
810 out_free:
811 	if(sem_io != fast_sem_io)
812 		ipc_free(sem_io, sizeof(ushort)*nsems);
813 	return err;
814 }
815 
816 struct sem_setbuf {
817 	uid_t	uid;
818 	gid_t	gid;
819 	mode_t	mode;
820 };
821 
822 static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
823 {
824 	switch(version) {
825 	case IPC_64:
826 	    {
827 		struct semid64_ds tbuf;
828 
829 		if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
830 			return -EFAULT;
831 
832 		out->uid	= tbuf.sem_perm.uid;
833 		out->gid	= tbuf.sem_perm.gid;
834 		out->mode	= tbuf.sem_perm.mode;
835 
836 		return 0;
837 	    }
838 	case IPC_OLD:
839 	    {
840 		struct semid_ds tbuf_old;
841 
842 		if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
843 			return -EFAULT;
844 
845 		out->uid	= tbuf_old.sem_perm.uid;
846 		out->gid	= tbuf_old.sem_perm.gid;
847 		out->mode	= tbuf_old.sem_perm.mode;
848 
849 		return 0;
850 	    }
851 	default:
852 		return -EINVAL;
853 	}
854 }
855 
856 static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
857 		int cmd, int version, union semun arg)
858 {
859 	struct sem_array *sma;
860 	int err;
861 	struct sem_setbuf setbuf;
862 	struct kern_ipc_perm *ipcp;
863 
864 	if(cmd == IPC_SET) {
865 		if(copy_semid_from_user (&setbuf, arg.buf, version))
866 			return -EFAULT;
867 	}
868 	sma = sem_lock(ns, semid);
869 	if(sma==NULL)
870 		return -EINVAL;
871 
872 	if (sem_checkid(ns,sma,semid)) {
873 		err=-EIDRM;
874 		goto out_unlock;
875 	}
876 	ipcp = &sma->sem_perm;
877 
878 	err = audit_ipc_obj(ipcp);
879 	if (err)
880 		goto out_unlock;
881 
882 	if (cmd == IPC_SET) {
883 		err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
884 		if (err)
885 			goto out_unlock;
886 	}
887 	if (current->euid != ipcp->cuid &&
888 	    current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
889 	    	err=-EPERM;
890 		goto out_unlock;
891 	}
892 
893 	err = security_sem_semctl(sma, cmd);
894 	if (err)
895 		goto out_unlock;
896 
897 	switch(cmd){
898 	case IPC_RMID:
899 		freeary(ns, sma, semid);
900 		err = 0;
901 		break;
902 	case IPC_SET:
903 		ipcp->uid = setbuf.uid;
904 		ipcp->gid = setbuf.gid;
905 		ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
906 				| (setbuf.mode & S_IRWXUGO);
907 		sma->sem_ctime = get_seconds();
908 		sem_unlock(sma);
909 		err = 0;
910 		break;
911 	default:
912 		sem_unlock(sma);
913 		err = -EINVAL;
914 		break;
915 	}
916 	return err;
917 
918 out_unlock:
919 	sem_unlock(sma);
920 	return err;
921 }
922 
923 asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
924 {
925 	int err = -EINVAL;
926 	int version;
927 	struct ipc_namespace *ns;
928 
929 	if (semid < 0)
930 		return -EINVAL;
931 
932 	version = ipc_parse_version(&cmd);
933 	ns = current->nsproxy->ipc_ns;
934 
935 	switch(cmd) {
936 	case IPC_INFO:
937 	case SEM_INFO:
938 	case SEM_STAT:
939 		err = semctl_nolock(ns,semid,semnum,cmd,version,arg);
940 		return err;
941 	case GETALL:
942 	case GETVAL:
943 	case GETPID:
944 	case GETNCNT:
945 	case GETZCNT:
946 	case IPC_STAT:
947 	case SETVAL:
948 	case SETALL:
949 		err = semctl_main(ns,semid,semnum,cmd,version,arg);
950 		return err;
951 	case IPC_RMID:
952 	case IPC_SET:
953 		mutex_lock(&sem_ids(ns).mutex);
954 		err = semctl_down(ns,semid,semnum,cmd,version,arg);
955 		mutex_unlock(&sem_ids(ns).mutex);
956 		return err;
957 	default:
958 		return -EINVAL;
959 	}
960 }
961 
962 static inline void lock_semundo(void)
963 {
964 	struct sem_undo_list *undo_list;
965 
966 	undo_list = current->sysvsem.undo_list;
967 	if (undo_list)
968 		spin_lock(&undo_list->lock);
969 }
970 
971 /* This code has an interaction with copy_semundo().
972  * Consider; two tasks are sharing the undo_list. task1
973  * acquires the undo_list lock in lock_semundo().  If task2 now
974  * exits before task1 releases the lock (by calling
975  * unlock_semundo()), then task1 will never call spin_unlock().
976  * This leave the sem_undo_list in a locked state.  If task1 now creats task3
977  * and once again shares the sem_undo_list, the sem_undo_list will still be
978  * locked, and future SEM_UNDO operations will deadlock.  This case is
979  * dealt with in copy_semundo() by having it reinitialize the spin lock when
980  * the refcnt goes from 1 to 2.
981  */
982 static inline void unlock_semundo(void)
983 {
984 	struct sem_undo_list *undo_list;
985 
986 	undo_list = current->sysvsem.undo_list;
987 	if (undo_list)
988 		spin_unlock(&undo_list->lock);
989 }
990 
991 
992 /* If the task doesn't already have a undo_list, then allocate one
993  * here.  We guarantee there is only one thread using this undo list,
994  * and current is THE ONE
995  *
996  * If this allocation and assignment succeeds, but later
997  * portions of this code fail, there is no need to free the sem_undo_list.
998  * Just let it stay associated with the task, and it'll be freed later
999  * at exit time.
1000  *
1001  * This can block, so callers must hold no locks.
1002  */
1003 static inline int get_undo_list(struct sem_undo_list **undo_listp)
1004 {
1005 	struct sem_undo_list *undo_list;
1006 
1007 	undo_list = current->sysvsem.undo_list;
1008 	if (!undo_list) {
1009 		undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
1010 		if (undo_list == NULL)
1011 			return -ENOMEM;
1012 		spin_lock_init(&undo_list->lock);
1013 		atomic_set(&undo_list->refcnt, 1);
1014 		current->sysvsem.undo_list = undo_list;
1015 	}
1016 	*undo_listp = undo_list;
1017 	return 0;
1018 }
1019 
1020 static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1021 {
1022 	struct sem_undo **last, *un;
1023 
1024 	last = &ulp->proc_list;
1025 	un = *last;
1026 	while(un != NULL) {
1027 		if(un->semid==semid)
1028 			break;
1029 		if(un->semid==-1) {
1030 			*last=un->proc_next;
1031 			kfree(un);
1032 		} else {
1033 			last=&un->proc_next;
1034 		}
1035 		un=*last;
1036 	}
1037 	return un;
1038 }
1039 
1040 static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
1041 {
1042 	struct sem_array *sma;
1043 	struct sem_undo_list *ulp;
1044 	struct sem_undo *un, *new;
1045 	int nsems;
1046 	int error;
1047 
1048 	error = get_undo_list(&ulp);
1049 	if (error)
1050 		return ERR_PTR(error);
1051 
1052 	lock_semundo();
1053 	un = lookup_undo(ulp, semid);
1054 	unlock_semundo();
1055 	if (likely(un!=NULL))
1056 		goto out;
1057 
1058 	/* no undo structure around - allocate one. */
1059 	sma = sem_lock(ns, semid);
1060 	un = ERR_PTR(-EINVAL);
1061 	if(sma==NULL)
1062 		goto out;
1063 	un = ERR_PTR(-EIDRM);
1064 	if (sem_checkid(ns,sma,semid)) {
1065 		sem_unlock(sma);
1066 		goto out;
1067 	}
1068 	nsems = sma->sem_nsems;
1069 	ipc_rcu_getref(sma);
1070 	sem_unlock(sma);
1071 
1072 	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
1073 	if (!new) {
1074 		ipc_lock_by_ptr(&sma->sem_perm);
1075 		ipc_rcu_putref(sma);
1076 		sem_unlock(sma);
1077 		return ERR_PTR(-ENOMEM);
1078 	}
1079 	new->semadj = (short *) &new[1];
1080 	new->semid = semid;
1081 
1082 	lock_semundo();
1083 	un = lookup_undo(ulp, semid);
1084 	if (un) {
1085 		unlock_semundo();
1086 		kfree(new);
1087 		ipc_lock_by_ptr(&sma->sem_perm);
1088 		ipc_rcu_putref(sma);
1089 		sem_unlock(sma);
1090 		goto out;
1091 	}
1092 	ipc_lock_by_ptr(&sma->sem_perm);
1093 	ipc_rcu_putref(sma);
1094 	if (sma->sem_perm.deleted) {
1095 		sem_unlock(sma);
1096 		unlock_semundo();
1097 		kfree(new);
1098 		un = ERR_PTR(-EIDRM);
1099 		goto out;
1100 	}
1101 	new->proc_next = ulp->proc_list;
1102 	ulp->proc_list = new;
1103 	new->id_next = sma->undo;
1104 	sma->undo = new;
1105 	sem_unlock(sma);
1106 	un = new;
1107 	unlock_semundo();
1108 out:
1109 	return un;
1110 }
1111 
1112 asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops,
1113 			unsigned nsops, const struct timespec __user *timeout)
1114 {
1115 	int error = -EINVAL;
1116 	struct sem_array *sma;
1117 	struct sembuf fast_sops[SEMOPM_FAST];
1118 	struct sembuf* sops = fast_sops, *sop;
1119 	struct sem_undo *un;
1120 	int undos = 0, alter = 0, max;
1121 	struct sem_queue queue;
1122 	unsigned long jiffies_left = 0;
1123 	struct ipc_namespace *ns;
1124 
1125 	ns = current->nsproxy->ipc_ns;
1126 
1127 	if (nsops < 1 || semid < 0)
1128 		return -EINVAL;
1129 	if (nsops > ns->sc_semopm)
1130 		return -E2BIG;
1131 	if(nsops > SEMOPM_FAST) {
1132 		sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
1133 		if(sops==NULL)
1134 			return -ENOMEM;
1135 	}
1136 	if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1137 		error=-EFAULT;
1138 		goto out_free;
1139 	}
1140 	if (timeout) {
1141 		struct timespec _timeout;
1142 		if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1143 			error = -EFAULT;
1144 			goto out_free;
1145 		}
1146 		if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1147 			_timeout.tv_nsec >= 1000000000L) {
1148 			error = -EINVAL;
1149 			goto out_free;
1150 		}
1151 		jiffies_left = timespec_to_jiffies(&_timeout);
1152 	}
1153 	max = 0;
1154 	for (sop = sops; sop < sops + nsops; sop++) {
1155 		if (sop->sem_num >= max)
1156 			max = sop->sem_num;
1157 		if (sop->sem_flg & SEM_UNDO)
1158 			undos = 1;
1159 		if (sop->sem_op != 0)
1160 			alter = 1;
1161 	}
1162 
1163 retry_undos:
1164 	if (undos) {
1165 		un = find_undo(ns, semid);
1166 		if (IS_ERR(un)) {
1167 			error = PTR_ERR(un);
1168 			goto out_free;
1169 		}
1170 	} else
1171 		un = NULL;
1172 
1173 	sma = sem_lock(ns, semid);
1174 	error=-EINVAL;
1175 	if(sma==NULL)
1176 		goto out_free;
1177 	error = -EIDRM;
1178 	if (sem_checkid(ns,sma,semid))
1179 		goto out_unlock_free;
1180 	/*
1181 	 * semid identifies are not unique - find_undo may have
1182 	 * allocated an undo structure, it was invalidated by an RMID
1183 	 * and now a new array with received the same id. Check and retry.
1184 	 */
1185 	if (un && un->semid == -1) {
1186 		sem_unlock(sma);
1187 		goto retry_undos;
1188 	}
1189 	error = -EFBIG;
1190 	if (max >= sma->sem_nsems)
1191 		goto out_unlock_free;
1192 
1193 	error = -EACCES;
1194 	if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1195 		goto out_unlock_free;
1196 
1197 	error = security_sem_semop(sma, sops, nsops, alter);
1198 	if (error)
1199 		goto out_unlock_free;
1200 
1201 	error = try_atomic_semop (sma, sops, nsops, un, current->tgid);
1202 	if (error <= 0) {
1203 		if (alter && error == 0)
1204 			update_queue (sma);
1205 		goto out_unlock_free;
1206 	}
1207 
1208 	/* We need to sleep on this operation, so we put the current
1209 	 * task into the pending queue and go to sleep.
1210 	 */
1211 
1212 	queue.sma = sma;
1213 	queue.sops = sops;
1214 	queue.nsops = nsops;
1215 	queue.undo = un;
1216 	queue.pid = current->tgid;
1217 	queue.id = semid;
1218 	queue.alter = alter;
1219 	if (alter)
1220 		append_to_queue(sma ,&queue);
1221 	else
1222 		prepend_to_queue(sma ,&queue);
1223 
1224 	queue.status = -EINTR;
1225 	queue.sleeper = current;
1226 	current->state = TASK_INTERRUPTIBLE;
1227 	sem_unlock(sma);
1228 
1229 	if (timeout)
1230 		jiffies_left = schedule_timeout(jiffies_left);
1231 	else
1232 		schedule();
1233 
1234 	error = queue.status;
1235 	while(unlikely(error == IN_WAKEUP)) {
1236 		cpu_relax();
1237 		error = queue.status;
1238 	}
1239 
1240 	if (error != -EINTR) {
1241 		/* fast path: update_queue already obtained all requested
1242 		 * resources */
1243 		goto out_free;
1244 	}
1245 
1246 	sma = sem_lock(ns, semid);
1247 	if(sma==NULL) {
1248 		BUG_ON(queue.prev != NULL);
1249 		error = -EIDRM;
1250 		goto out_free;
1251 	}
1252 
1253 	/*
1254 	 * If queue.status != -EINTR we are woken up by another process
1255 	 */
1256 	error = queue.status;
1257 	if (error != -EINTR) {
1258 		goto out_unlock_free;
1259 	}
1260 
1261 	/*
1262 	 * If an interrupt occurred we have to clean up the queue
1263 	 */
1264 	if (timeout && jiffies_left == 0)
1265 		error = -EAGAIN;
1266 	remove_from_queue(sma,&queue);
1267 	goto out_unlock_free;
1268 
1269 out_unlock_free:
1270 	sem_unlock(sma);
1271 out_free:
1272 	if(sops != fast_sops)
1273 		kfree(sops);
1274 	return error;
1275 }
1276 
1277 asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsops)
1278 {
1279 	return sys_semtimedop(semid, tsops, nsops, NULL);
1280 }
1281 
1282 /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1283  * parent and child tasks.
1284  *
1285  * See the notes above unlock_semundo() regarding the spin_lock_init()
1286  * in this code.  Initialize the undo_list->lock here instead of get_undo_list()
1287  * because of the reasoning in the comment above unlock_semundo.
1288  */
1289 
1290 int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1291 {
1292 	struct sem_undo_list *undo_list;
1293 	int error;
1294 
1295 	if (clone_flags & CLONE_SYSVSEM) {
1296 		error = get_undo_list(&undo_list);
1297 		if (error)
1298 			return error;
1299 		atomic_inc(&undo_list->refcnt);
1300 		tsk->sysvsem.undo_list = undo_list;
1301 	} else
1302 		tsk->sysvsem.undo_list = NULL;
1303 
1304 	return 0;
1305 }
1306 
1307 /*
1308  * add semadj values to semaphores, free undo structures.
1309  * undo structures are not freed when semaphore arrays are destroyed
1310  * so some of them may be out of date.
1311  * IMPLEMENTATION NOTE: There is some confusion over whether the
1312  * set of adjustments that needs to be done should be done in an atomic
1313  * manner or not. That is, if we are attempting to decrement the semval
1314  * should we queue up and wait until we can do so legally?
1315  * The original implementation attempted to do this (queue and wait).
1316  * The current implementation does not do so. The POSIX standard
1317  * and SVID should be consulted to determine what behavior is mandated.
1318  */
1319 void exit_sem(struct task_struct *tsk)
1320 {
1321 	struct sem_undo_list *undo_list;
1322 	struct sem_undo *u, **up;
1323 	struct ipc_namespace *ns;
1324 
1325 	undo_list = tsk->sysvsem.undo_list;
1326 	if (!undo_list)
1327 		return;
1328 
1329 	if (!atomic_dec_and_test(&undo_list->refcnt))
1330 		return;
1331 
1332 	ns = tsk->nsproxy->ipc_ns;
1333 	/* There's no need to hold the semundo list lock, as current
1334          * is the last task exiting for this undo list.
1335 	 */
1336 	for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
1337 		struct sem_array *sma;
1338 		int nsems, i;
1339 		struct sem_undo *un, **unp;
1340 		int semid;
1341 
1342 		semid = u->semid;
1343 
1344 		if(semid == -1)
1345 			continue;
1346 		sma = sem_lock(ns, semid);
1347 		if (sma == NULL)
1348 			continue;
1349 
1350 		if (u->semid == -1)
1351 			goto next_entry;
1352 
1353 		BUG_ON(sem_checkid(ns,sma,u->semid));
1354 
1355 		/* remove u from the sma->undo list */
1356 		for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
1357 			if (u == un)
1358 				goto found;
1359 		}
1360 		printk ("exit_sem undo list error id=%d\n", u->semid);
1361 		goto next_entry;
1362 found:
1363 		*unp = un->id_next;
1364 		/* perform adjustments registered in u */
1365 		nsems = sma->sem_nsems;
1366 		for (i = 0; i < nsems; i++) {
1367 			struct sem * semaphore = &sma->sem_base[i];
1368 			if (u->semadj[i]) {
1369 				semaphore->semval += u->semadj[i];
1370 				/*
1371 				 * Range checks of the new semaphore value,
1372 				 * not defined by sus:
1373 				 * - Some unices ignore the undo entirely
1374 				 *   (e.g. HP UX 11i 11.22, Tru64 V5.1)
1375 				 * - some cap the value (e.g. FreeBSD caps
1376 				 *   at 0, but doesn't enforce SEMVMX)
1377 				 *
1378 				 * Linux caps the semaphore value, both at 0
1379 				 * and at SEMVMX.
1380 				 *
1381 				 * 	Manfred <manfred@colorfullife.com>
1382 				 */
1383 				if (semaphore->semval < 0)
1384 					semaphore->semval = 0;
1385 				if (semaphore->semval > SEMVMX)
1386 					semaphore->semval = SEMVMX;
1387 				semaphore->sempid = current->tgid;
1388 			}
1389 		}
1390 		sma->sem_otime = get_seconds();
1391 		/* maybe some queued-up processes were waiting for this */
1392 		update_queue(sma);
1393 next_entry:
1394 		sem_unlock(sma);
1395 	}
1396 	kfree(undo_list);
1397 }
1398 
1399 #ifdef CONFIG_PROC_FS
1400 static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
1401 {
1402 	struct sem_array *sma = it;
1403 
1404 	return seq_printf(s,
1405 			  "%10d %10d  %4o %10lu %5u %5u %5u %5u %10lu %10lu\n",
1406 			  sma->sem_perm.key,
1407 			  sma->sem_id,
1408 			  sma->sem_perm.mode,
1409 			  sma->sem_nsems,
1410 			  sma->sem_perm.uid,
1411 			  sma->sem_perm.gid,
1412 			  sma->sem_perm.cuid,
1413 			  sma->sem_perm.cgid,
1414 			  sma->sem_otime,
1415 			  sma->sem_ctime);
1416 }
1417 #endif
1418