mqueue.c revision 7b7a317cf863559b49b548a8b97b2f4bdf1e149e 
1/*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5 *                          Michal Wronski          (Michal.Wronski@motorola.com)
6 *
7 * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8 * Lockless receive & send, fd based notify:
9 * 			    Manfred Spraul	    (manfred@colorfullife.com)
10 *
11 * This file is released under the GPL.
12 */
13
14#include <linux/capability.h>
15#include <linux/init.h>
16#include <linux/pagemap.h>
17#include <linux/file.h>
18#include <linux/mount.h>
19#include <linux/namei.h>
20#include <linux/sysctl.h>
21#include <linux/poll.h>
22#include <linux/mqueue.h>
23#include <linux/msg.h>
24#include <linux/skbuff.h>
25#include <linux/netlink.h>
26#include <linux/syscalls.h>
27#include <linux/signal.h>
28#include <linux/mutex.h>
29
30#include <net/sock.h>
31#include "util.h"
32
33#define MQUEUE_MAGIC	0x19800202
34#define DIRENT_SIZE	20
35#define FILENT_SIZE	80
36
37#define SEND		0
38#define RECV		1
39
40#define STATE_NONE	0
41#define STATE_PENDING	1
42#define STATE_READY	2
43
44/* used by sysctl */
45#define FS_MQUEUE 	1
46#define CTL_QUEUESMAX 	2
47#define CTL_MSGMAX 	3
48#define CTL_MSGSIZEMAX 	4
49
50/* default values */
51#define DFLT_QUEUESMAX	256	/* max number of message queues */
52#define DFLT_MSGMAX 	10	/* max number of messages in each queue */
53#define HARD_MSGMAX 	(131072/sizeof(void*))
54#define DFLT_MSGSIZEMAX 8192	/* max message size */
55
56
57struct ext_wait_queue {		/* queue of sleeping tasks */
58	struct task_struct *task;
59	struct list_head list;
60	struct msg_msg *msg;	/* ptr of loaded message */
61	int state;		/* one of STATE_* values */
62};
63
64struct mqueue_inode_info {
65	spinlock_t lock;
66	struct inode vfs_inode;
67	wait_queue_head_t wait_q;
68
69	struct msg_msg **messages;
70	struct mq_attr attr;
71
72	struct sigevent notify;
73	pid_t notify_owner;
74	struct user_struct *user;	/* user who created, for accounting */
75	struct sock *notify_sock;
76	struct sk_buff *notify_cookie;
77
78	/* for tasks waiting for free space and messages, respectively */
79	struct ext_wait_queue e_wait_q[2];
80
81	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
82};
83
84static struct inode_operations mqueue_dir_inode_operations;
85static struct file_operations mqueue_file_operations;
86static struct super_operations mqueue_super_ops;
87static void remove_notification(struct mqueue_inode_info *info);
88
89static spinlock_t mq_lock;
90static kmem_cache_t *mqueue_inode_cachep;
91static struct vfsmount *mqueue_mnt;
92
93static unsigned int queues_count;
94static unsigned int queues_max 	= DFLT_QUEUESMAX;
95static unsigned int msg_max 	= DFLT_MSGMAX;
96static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
97
98static struct ctl_table_header * mq_sysctl_table;
99
100static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
101{
102	return container_of(inode, struct mqueue_inode_info, vfs_inode);
103}
104
105static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
106							struct mq_attr *attr)
107{
108	struct inode *inode;
109
110	inode = new_inode(sb);
111	if (inode) {
112		inode->i_mode = mode;
113		inode->i_uid = current->fsuid;
114		inode->i_gid = current->fsgid;
115		inode->i_blksize = PAGE_CACHE_SIZE;
116		inode->i_blocks = 0;
117		inode->i_mtime = inode->i_ctime = inode->i_atime =
118				CURRENT_TIME;
119
120		if (S_ISREG(mode)) {
121			struct mqueue_inode_info *info;
122			struct task_struct *p = current;
123			struct user_struct *u = p->user;
124			unsigned long mq_bytes, mq_msg_tblsz;
125
126			inode->i_fop = &mqueue_file_operations;
127			inode->i_size = FILENT_SIZE;
128			/* mqueue specific info */
129			info = MQUEUE_I(inode);
130			spin_lock_init(&info->lock);
131			init_waitqueue_head(&info->wait_q);
132			INIT_LIST_HEAD(&info->e_wait_q[0].list);
133			INIT_LIST_HEAD(&info->e_wait_q[1].list);
134			info->messages = NULL;
135			info->notify_owner = 0;
136			info->qsize = 0;
137			info->user = NULL;	/* set when all is ok */
138			memset(&info->attr, 0, sizeof(info->attr));
139			info->attr.mq_maxmsg = DFLT_MSGMAX;
140			info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
141			if (attr) {
142				info->attr.mq_maxmsg = attr->mq_maxmsg;
143				info->attr.mq_msgsize = attr->mq_msgsize;
144			}
145			mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
146			mq_bytes = (mq_msg_tblsz +
147				(info->attr.mq_maxmsg * info->attr.mq_msgsize));
148
149			spin_lock(&mq_lock);
150			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
151		 	    u->mq_bytes + mq_bytes >
152			    p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
153				spin_unlock(&mq_lock);
154				goto out_inode;
155			}
156			u->mq_bytes += mq_bytes;
157			spin_unlock(&mq_lock);
158
159			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
160			if (!info->messages) {
161				spin_lock(&mq_lock);
162				u->mq_bytes -= mq_bytes;
163				spin_unlock(&mq_lock);
164				goto out_inode;
165			}
166			/* all is ok */
167			info->user = get_uid(u);
168		} else if (S_ISDIR(mode)) {
169			inode->i_nlink++;
170			/* Some things misbehave if size == 0 on a directory */
171			inode->i_size = 2 * DIRENT_SIZE;
172			inode->i_op = &mqueue_dir_inode_operations;
173			inode->i_fop = &simple_dir_operations;
174		}
175	}
176	return inode;
177out_inode:
178	make_bad_inode(inode);
179	iput(inode);
180	return NULL;
181}
182
183static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
184{
185	struct inode *inode;
186
187	sb->s_blocksize = PAGE_CACHE_SIZE;
188	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
189	sb->s_magic = MQUEUE_MAGIC;
190	sb->s_op = &mqueue_super_ops;
191
192	inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
193	if (!inode)
194		return -ENOMEM;
195
196	sb->s_root = d_alloc_root(inode);
197	if (!sb->s_root) {
198		iput(inode);
199		return -ENOMEM;
200	}
201
202	return 0;
203}
204
205static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
206					 int flags, const char *dev_name,
207					 void *data)
208{
209	return get_sb_single(fs_type, flags, data, mqueue_fill_super);
210}
211
212static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
213{
214	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
215
216	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
217		SLAB_CTOR_CONSTRUCTOR)
218		inode_init_once(&p->vfs_inode);
219}
220
221static struct inode *mqueue_alloc_inode(struct super_block *sb)
222{
223	struct mqueue_inode_info *ei;
224
225	ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
226	if (!ei)
227		return NULL;
228	return &ei->vfs_inode;
229}
230
231static void mqueue_destroy_inode(struct inode *inode)
232{
233	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
234}
235
236static void mqueue_delete_inode(struct inode *inode)
237{
238	struct mqueue_inode_info *info;
239	struct user_struct *user;
240	unsigned long mq_bytes;
241	int i;
242
243	if (S_ISDIR(inode->i_mode)) {
244		clear_inode(inode);
245		return;
246	}
247	info = MQUEUE_I(inode);
248	spin_lock(&info->lock);
249	for (i = 0; i < info->attr.mq_curmsgs; i++)
250		free_msg(info->messages[i]);
251	kfree(info->messages);
252	spin_unlock(&info->lock);
253
254	clear_inode(inode);
255
256	mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
257		   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
258	user = info->user;
259	if (user) {
260		spin_lock(&mq_lock);
261		user->mq_bytes -= mq_bytes;
262		queues_count--;
263		spin_unlock(&mq_lock);
264		free_uid(user);
265	}
266}
267
268static int mqueue_create(struct inode *dir, struct dentry *dentry,
269				int mode, struct nameidata *nd)
270{
271	struct inode *inode;
272	struct mq_attr *attr = dentry->d_fsdata;
273	int error;
274
275	spin_lock(&mq_lock);
276	if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
277		error = -ENOSPC;
278		goto out_lock;
279	}
280	queues_count++;
281	spin_unlock(&mq_lock);
282
283	inode = mqueue_get_inode(dir->i_sb, mode, attr);
284	if (!inode) {
285		error = -ENOMEM;
286		spin_lock(&mq_lock);
287		queues_count--;
288		goto out_lock;
289	}
290
291	dir->i_size += DIRENT_SIZE;
292	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
293
294	d_instantiate(dentry, inode);
295	dget(dentry);
296	return 0;
297out_lock:
298	spin_unlock(&mq_lock);
299	return error;
300}
301
302static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
303{
304  	struct inode *inode = dentry->d_inode;
305
306	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
307	dir->i_size -= DIRENT_SIZE;
308  	inode->i_nlink--;
309  	dput(dentry);
310  	return 0;
311}
312
313/*
314*	This is routine for system read from queue file.
315*	To avoid mess with doing here some sort of mq_receive we allow
316*	to read only queue size & notification info (the only values
317*	that are interesting from user point of view and aren't accessible
318*	through std routines)
319*/
320static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
321				size_t count, loff_t * off)
322{
323	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
324	char buffer[FILENT_SIZE];
325	size_t slen;
326	loff_t o;
327
328	if (!count)
329		return 0;
330
331	spin_lock(&info->lock);
332	snprintf(buffer, sizeof(buffer),
333			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
334			info->qsize,
335			info->notify_owner ? info->notify.sigev_notify : 0,
336			(info->notify_owner &&
337			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
338				info->notify.sigev_signo : 0,
339			info->notify_owner);
340	spin_unlock(&info->lock);
341	buffer[sizeof(buffer)-1] = '\0';
342	slen = strlen(buffer)+1;
343
344	o = *off;
345	if (o > slen)
346		return 0;
347
348	if (o + count > slen)
349		count = slen - o;
350
351	if (copy_to_user(u_data, buffer + o, count))
352		return -EFAULT;
353
354	*off = o + count;
355	filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
356	return count;
357}
358
359static int mqueue_flush_file(struct file *filp)
360{
361	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
362
363	spin_lock(&info->lock);
364	if (current->tgid == info->notify_owner)
365		remove_notification(info);
366
367	spin_unlock(&info->lock);
368	return 0;
369}
370
371static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
372{
373	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
374	int retval = 0;
375
376	poll_wait(filp, &info->wait_q, poll_tab);
377
378	spin_lock(&info->lock);
379	if (info->attr.mq_curmsgs)
380		retval = POLLIN | POLLRDNORM;
381
382	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
383		retval |= POLLOUT | POLLWRNORM;
384	spin_unlock(&info->lock);
385
386	return retval;
387}
388
389/* Adds current to info->e_wait_q[sr] before element with smaller prio */
390static void wq_add(struct mqueue_inode_info *info, int sr,
391			struct ext_wait_queue *ewp)
392{
393	struct ext_wait_queue *walk;
394
395	ewp->task = current;
396
397	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
398		if (walk->task->static_prio <= current->static_prio) {
399			list_add_tail(&ewp->list, &walk->list);
400			return;
401		}
402	}
403	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
404}
405
406/*
407 * Puts current task to sleep. Caller must hold queue lock. After return
408 * lock isn't held.
409 * sr: SEND or RECV
410 */
411static int wq_sleep(struct mqueue_inode_info *info, int sr,
412			long timeout, struct ext_wait_queue *ewp)
413{
414	int retval;
415	signed long time;
416
417	wq_add(info, sr, ewp);
418
419	for (;;) {
420		set_current_state(TASK_INTERRUPTIBLE);
421
422		spin_unlock(&info->lock);
423		time = schedule_timeout(timeout);
424
425		while (ewp->state == STATE_PENDING)
426			cpu_relax();
427
428		if (ewp->state == STATE_READY) {
429			retval = 0;
430			goto out;
431		}
432		spin_lock(&info->lock);
433		if (ewp->state == STATE_READY) {
434			retval = 0;
435			goto out_unlock;
436		}
437		if (signal_pending(current)) {
438			retval = -ERESTARTSYS;
439			break;
440		}
441		if (time == 0) {
442			retval = -ETIMEDOUT;
443			break;
444		}
445	}
446	list_del(&ewp->list);
447out_unlock:
448	spin_unlock(&info->lock);
449out:
450	return retval;
451}
452
453/*
454 * Returns waiting task that should be serviced first or NULL if none exists
455 */
456static struct ext_wait_queue *wq_get_first_waiter(
457		struct mqueue_inode_info *info, int sr)
458{
459	struct list_head *ptr;
460
461	ptr = info->e_wait_q[sr].list.prev;
462	if (ptr == &info->e_wait_q[sr].list)
463		return NULL;
464	return list_entry(ptr, struct ext_wait_queue, list);
465}
466
467/* Auxiliary functions to manipulate messages' list */
468static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
469{
470	int k;
471
472	k = info->attr.mq_curmsgs - 1;
473	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
474		info->messages[k + 1] = info->messages[k];
475		k--;
476	}
477	info->attr.mq_curmsgs++;
478	info->qsize += ptr->m_ts;
479	info->messages[k + 1] = ptr;
480}
481
482static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
483{
484	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
485	return info->messages[info->attr.mq_curmsgs];
486}
487
488static inline void set_cookie(struct sk_buff *skb, char code)
489{
490	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
491}
492
493/*
494 * The next function is only to split too long sys_mq_timedsend
495 */
496static void __do_notify(struct mqueue_inode_info *info)
497{
498	/* notification
499	 * invoked when there is registered process and there isn't process
500	 * waiting synchronously for message AND state of queue changed from
501	 * empty to not empty. Here we are sure that no one is waiting
502	 * synchronously. */
503	if (info->notify_owner &&
504	    info->attr.mq_curmsgs == 1) {
505		struct siginfo sig_i;
506		switch (info->notify.sigev_notify) {
507		case SIGEV_NONE:
508			break;
509		case SIGEV_SIGNAL:
510			/* sends signal */
511
512			sig_i.si_signo = info->notify.sigev_signo;
513			sig_i.si_errno = 0;
514			sig_i.si_code = SI_MESGQ;
515			sig_i.si_value = info->notify.sigev_value;
516			sig_i.si_pid = current->tgid;
517			sig_i.si_uid = current->uid;
518
519			kill_proc_info(info->notify.sigev_signo,
520				       &sig_i, info->notify_owner);
521			break;
522		case SIGEV_THREAD:
523			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
524			netlink_sendskb(info->notify_sock,
525					info->notify_cookie, 0);
526			break;
527		}
528		/* after notification unregisters process */
529		info->notify_owner = 0;
530	}
531	wake_up(&info->wait_q);
532}
533
534static long prepare_timeout(const struct timespec __user *u_arg)
535{
536	struct timespec ts, nowts;
537	long timeout;
538
539	if (u_arg) {
540		if (unlikely(copy_from_user(&ts, u_arg,
541					sizeof(struct timespec))))
542			return -EFAULT;
543
544		if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
545			|| ts.tv_nsec >= NSEC_PER_SEC))
546			return -EINVAL;
547		nowts = CURRENT_TIME;
548		/* first subtract as jiffies can't be too big */
549		ts.tv_sec -= nowts.tv_sec;
550		if (ts.tv_nsec < nowts.tv_nsec) {
551			ts.tv_nsec += NSEC_PER_SEC;
552			ts.tv_sec--;
553		}
554		ts.tv_nsec -= nowts.tv_nsec;
555		if (ts.tv_sec < 0)
556			return 0;
557
558		timeout = timespec_to_jiffies(&ts) + 1;
559	} else
560		return MAX_SCHEDULE_TIMEOUT;
561
562	return timeout;
563}
564
565static void remove_notification(struct mqueue_inode_info *info)
566{
567	if (info->notify_owner != 0 &&
568	    info->notify.sigev_notify == SIGEV_THREAD) {
569		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
570		netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
571	}
572	info->notify_owner = 0;
573}
574
575static int mq_attr_ok(struct mq_attr *attr)
576{
577	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
578		return 0;
579	if (capable(CAP_SYS_RESOURCE)) {
580		if (attr->mq_maxmsg > HARD_MSGMAX)
581			return 0;
582	} else {
583		if (attr->mq_maxmsg > msg_max ||
584				attr->mq_msgsize > msgsize_max)
585			return 0;
586	}
587	/* check for overflow */
588	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
589		return 0;
590	if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
591	    (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
592	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
593		return 0;
594	return 1;
595}
596
597/*
598 * Invoked when creating a new queue via sys_mq_open
599 */
600static struct file *do_create(struct dentry *dir, struct dentry *dentry,
601			int oflag, mode_t mode, struct mq_attr __user *u_attr)
602{
603	struct mq_attr attr;
604	int ret;
605
606	if (u_attr) {
607		ret = -EFAULT;
608		if (copy_from_user(&attr, u_attr, sizeof(attr)))
609			goto out;
610		ret = -EINVAL;
611		if (!mq_attr_ok(&attr))
612			goto out;
613		/* store for use during create */
614		dentry->d_fsdata = &attr;
615	}
616
617	mode &= ~current->fs->umask;
618	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
619	dentry->d_fsdata = NULL;
620	if (ret)
621		goto out;
622
623	return dentry_open(dentry, mqueue_mnt, oflag);
624
625out:
626	dput(dentry);
627	mntput(mqueue_mnt);
628	return ERR_PTR(ret);
629}
630
631/* Opens existing queue */
632static struct file *do_open(struct dentry *dentry, int oflag)
633{
634static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
635					MAY_READ | MAY_WRITE };
636
637	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
638		dput(dentry);
639		mntput(mqueue_mnt);
640		return ERR_PTR(-EINVAL);
641	}
642
643	if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
644		dput(dentry);
645		mntput(mqueue_mnt);
646		return ERR_PTR(-EACCES);
647	}
648
649	return dentry_open(dentry, mqueue_mnt, oflag);
650}
651
652asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
653				struct mq_attr __user *u_attr)
654{
655	struct dentry *dentry;
656	struct file *filp;
657	char *name;
658	int fd, error;
659
660	if (IS_ERR(name = getname(u_name)))
661		return PTR_ERR(name);
662
663	fd = get_unused_fd();
664	if (fd < 0)
665		goto out_putname;
666
667	mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
668	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
669	if (IS_ERR(dentry)) {
670		error = PTR_ERR(dentry);
671		goto out_err;
672	}
673	mntget(mqueue_mnt);
674
675	if (oflag & O_CREAT) {
676		if (dentry->d_inode) {	/* entry already exists */
677			error = -EEXIST;
678			if (oflag & O_EXCL)
679				goto out;
680			filp = do_open(dentry, oflag);
681		} else {
682			filp = do_create(mqueue_mnt->mnt_root, dentry,
683						oflag, mode, u_attr);
684		}
685	} else {
686		error = -ENOENT;
687		if (!dentry->d_inode)
688			goto out;
689		filp = do_open(dentry, oflag);
690	}
691
692	if (IS_ERR(filp)) {
693		error = PTR_ERR(filp);
694		goto out_putfd;
695	}
696
697	set_close_on_exec(fd, 1);
698	fd_install(fd, filp);
699	goto out_upsem;
700
701out:
702	dput(dentry);
703	mntput(mqueue_mnt);
704out_putfd:
705	put_unused_fd(fd);
706out_err:
707	fd = error;
708out_upsem:
709	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
710out_putname:
711	putname(name);
712	return fd;
713}
714
715asmlinkage long sys_mq_unlink(const char __user *u_name)
716{
717	int err;
718	char *name;
719	struct dentry *dentry;
720	struct inode *inode = NULL;
721
722	name = getname(u_name);
723	if (IS_ERR(name))
724		return PTR_ERR(name);
725
726	mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
727	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
728	if (IS_ERR(dentry)) {
729		err = PTR_ERR(dentry);
730		goto out_unlock;
731	}
732
733	if (!dentry->d_inode) {
734		err = -ENOENT;
735		goto out_err;
736	}
737
738	inode = dentry->d_inode;
739	if (inode)
740		atomic_inc(&inode->i_count);
741
742	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
743out_err:
744	dput(dentry);
745
746out_unlock:
747	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
748	putname(name);
749	if (inode)
750		iput(inode);
751
752	return err;
753}
754
755/* Pipelined send and receive functions.
756 *
757 * If a receiver finds no waiting message, then it registers itself in the
758 * list of waiting receivers. A sender checks that list before adding the new
759 * message into the message array. If there is a waiting receiver, then it
760 * bypasses the message array and directly hands the message over to the
761 * receiver.
762 * The receiver accepts the message and returns without grabbing the queue
763 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
764 * are necessary. The same algorithm is used for sysv semaphores, see
765 * ipc/sem.c for more details.
766 *
767 * The same algorithm is used for senders.
768 */
769
770/* pipelined_send() - send a message directly to the task waiting in
771 * sys_mq_timedreceive() (without inserting message into a queue).
772 */
773static inline void pipelined_send(struct mqueue_inode_info *info,
774				  struct msg_msg *message,
775				  struct ext_wait_queue *receiver)
776{
777	receiver->msg = message;
778	list_del(&receiver->list);
779	receiver->state = STATE_PENDING;
780	wake_up_process(receiver->task);
781	smp_wmb();
782	receiver->state = STATE_READY;
783}
784
785/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
786 * gets its message and put to the queue (we have one free place for sure). */
787static inline void pipelined_receive(struct mqueue_inode_info *info)
788{
789	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
790
791	if (!sender) {
792		/* for poll */
793		wake_up_interruptible(&info->wait_q);
794		return;
795	}
796	msg_insert(sender->msg, info);
797	list_del(&sender->list);
798	sender->state = STATE_PENDING;
799	wake_up_process(sender->task);
800	smp_wmb();
801	sender->state = STATE_READY;
802}
803
804asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
805	size_t msg_len, unsigned int msg_prio,
806	const struct timespec __user *u_abs_timeout)
807{
808	struct file *filp;
809	struct inode *inode;
810	struct ext_wait_queue wait;
811	struct ext_wait_queue *receiver;
812	struct msg_msg *msg_ptr;
813	struct mqueue_inode_info *info;
814	long timeout;
815	int ret;
816
817	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
818		return -EINVAL;
819
820	timeout = prepare_timeout(u_abs_timeout);
821
822	ret = -EBADF;
823	filp = fget(mqdes);
824	if (unlikely(!filp))
825		goto out;
826
827	inode = filp->f_dentry->d_inode;
828	if (unlikely(filp->f_op != &mqueue_file_operations))
829		goto out_fput;
830	info = MQUEUE_I(inode);
831
832	if (unlikely(!(filp->f_mode & FMODE_WRITE)))
833		goto out_fput;
834
835	if (unlikely(msg_len > info->attr.mq_msgsize)) {
836		ret = -EMSGSIZE;
837		goto out_fput;
838	}
839
840	/* First try to allocate memory, before doing anything with
841	 * existing queues. */
842	msg_ptr = load_msg(u_msg_ptr, msg_len);
843	if (IS_ERR(msg_ptr)) {
844		ret = PTR_ERR(msg_ptr);
845		goto out_fput;
846	}
847	msg_ptr->m_ts = msg_len;
848	msg_ptr->m_type = msg_prio;
849
850	spin_lock(&info->lock);
851
852	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
853		if (filp->f_flags & O_NONBLOCK) {
854			spin_unlock(&info->lock);
855			ret = -EAGAIN;
856		} else if (unlikely(timeout < 0)) {
857			spin_unlock(&info->lock);
858			ret = timeout;
859		} else {
860			wait.task = current;
861			wait.msg = (void *) msg_ptr;
862			wait.state = STATE_NONE;
863			ret = wq_sleep(info, SEND, timeout, &wait);
864		}
865		if (ret < 0)
866			free_msg(msg_ptr);
867	} else {
868		receiver = wq_get_first_waiter(info, RECV);
869		if (receiver) {
870			pipelined_send(info, msg_ptr, receiver);
871		} else {
872			/* adds message to the queue */
873			msg_insert(msg_ptr, info);
874			__do_notify(info);
875		}
876		inode->i_atime = inode->i_mtime = inode->i_ctime =
877				CURRENT_TIME;
878		spin_unlock(&info->lock);
879		ret = 0;
880	}
881out_fput:
882	fput(filp);
883out:
884	return ret;
885}
886
887asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
888	size_t msg_len, unsigned int __user *u_msg_prio,
889	const struct timespec __user *u_abs_timeout)
890{
891	long timeout;
892	ssize_t ret;
893	struct msg_msg *msg_ptr;
894	struct file *filp;
895	struct inode *inode;
896	struct mqueue_inode_info *info;
897	struct ext_wait_queue wait;
898
899	timeout = prepare_timeout(u_abs_timeout);
900
901	ret = -EBADF;
902	filp = fget(mqdes);
903	if (unlikely(!filp))
904		goto out;
905
906	inode = filp->f_dentry->d_inode;
907	if (unlikely(filp->f_op != &mqueue_file_operations))
908		goto out_fput;
909	info = MQUEUE_I(inode);
910
911	if (unlikely(!(filp->f_mode & FMODE_READ)))
912		goto out_fput;
913
914	/* checks if buffer is big enough */
915	if (unlikely(msg_len < info->attr.mq_msgsize)) {
916		ret = -EMSGSIZE;
917		goto out_fput;
918	}
919
920	spin_lock(&info->lock);
921	if (info->attr.mq_curmsgs == 0) {
922		if (filp->f_flags & O_NONBLOCK) {
923			spin_unlock(&info->lock);
924			ret = -EAGAIN;
925			msg_ptr = NULL;
926		} else if (unlikely(timeout < 0)) {
927			spin_unlock(&info->lock);
928			ret = timeout;
929			msg_ptr = NULL;
930		} else {
931			wait.task = current;
932			wait.state = STATE_NONE;
933			ret = wq_sleep(info, RECV, timeout, &wait);
934			msg_ptr = wait.msg;
935		}
936	} else {
937		msg_ptr = msg_get(info);
938
939		inode->i_atime = inode->i_mtime = inode->i_ctime =
940				CURRENT_TIME;
941
942		/* There is now free space in queue. */
943		pipelined_receive(info);
944		spin_unlock(&info->lock);
945		ret = 0;
946	}
947	if (ret == 0) {
948		ret = msg_ptr->m_ts;
949
950		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
951			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
952			ret = -EFAULT;
953		}
954		free_msg(msg_ptr);
955	}
956out_fput:
957	fput(filp);
958out:
959	return ret;
960}
961
962/*
963 * Notes: the case when user wants us to deregister (with NULL as pointer)
964 * and he isn't currently owner of notification, will be silently discarded.
965 * It isn't explicitly defined in the POSIX.
966 */
967asmlinkage long sys_mq_notify(mqd_t mqdes,
968				const struct sigevent __user *u_notification)
969{
970	int ret;
971	struct file *filp;
972	struct sock *sock;
973	struct inode *inode;
974	struct sigevent notification;
975	struct mqueue_inode_info *info;
976	struct sk_buff *nc;
977
978	nc = NULL;
979	sock = NULL;
980	if (u_notification != NULL) {
981		if (copy_from_user(&notification, u_notification,
982					sizeof(struct sigevent)))
983			return -EFAULT;
984
985		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
986			     notification.sigev_notify != SIGEV_SIGNAL &&
987			     notification.sigev_notify != SIGEV_THREAD))
988			return -EINVAL;
989		if (notification.sigev_notify == SIGEV_SIGNAL &&
990			!valid_signal(notification.sigev_signo)) {
991			return -EINVAL;
992		}
993		if (notification.sigev_notify == SIGEV_THREAD) {
994			/* create the notify skb */
995			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
996			ret = -ENOMEM;
997			if (!nc)
998				goto out;
999			ret = -EFAULT;
1000			if (copy_from_user(nc->data,
1001					notification.sigev_value.sival_ptr,
1002					NOTIFY_COOKIE_LEN)) {
1003				goto out;
1004			}
1005
1006			/* TODO: add a header? */
1007			skb_put(nc, NOTIFY_COOKIE_LEN);
1008			/* and attach it to the socket */
1009retry:
1010			filp = fget(notification.sigev_signo);
1011			ret = -EBADF;
1012			if (!filp)
1013				goto out;
1014			sock = netlink_getsockbyfilp(filp);
1015			fput(filp);
1016			if (IS_ERR(sock)) {
1017				ret = PTR_ERR(sock);
1018				sock = NULL;
1019				goto out;
1020			}
1021
1022			ret = netlink_attachskb(sock, nc, 0,
1023					MAX_SCHEDULE_TIMEOUT, NULL);
1024			if (ret == 1)
1025		       		goto retry;
1026			if (ret) {
1027				sock = NULL;
1028				nc = NULL;
1029				goto out;
1030			}
1031		}
1032	}
1033
1034	ret = -EBADF;
1035	filp = fget(mqdes);
1036	if (!filp)
1037		goto out;
1038
1039	inode = filp->f_dentry->d_inode;
1040	if (unlikely(filp->f_op != &mqueue_file_operations))
1041		goto out_fput;
1042	info = MQUEUE_I(inode);
1043
1044	ret = 0;
1045	spin_lock(&info->lock);
1046	if (u_notification == NULL) {
1047		if (info->notify_owner == current->tgid) {
1048			remove_notification(info);
1049			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1050		}
1051	} else if (info->notify_owner != 0) {
1052		ret = -EBUSY;
1053	} else {
1054		switch (notification.sigev_notify) {
1055		case SIGEV_NONE:
1056			info->notify.sigev_notify = SIGEV_NONE;
1057			break;
1058		case SIGEV_THREAD:
1059			info->notify_sock = sock;
1060			info->notify_cookie = nc;
1061			sock = NULL;
1062			nc = NULL;
1063			info->notify.sigev_notify = SIGEV_THREAD;
1064			break;
1065		case SIGEV_SIGNAL:
1066			info->notify.sigev_signo = notification.sigev_signo;
1067			info->notify.sigev_value = notification.sigev_value;
1068			info->notify.sigev_notify = SIGEV_SIGNAL;
1069			break;
1070		}
1071		info->notify_owner = current->tgid;
1072		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1073	}
1074	spin_unlock(&info->lock);
1075out_fput:
1076	fput(filp);
1077out:
1078	if (sock) {
1079		netlink_detachskb(sock, nc);
1080	} else if (nc) {
1081		dev_kfree_skb(nc);
1082	}
1083	return ret;
1084}
1085
1086asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1087			const struct mq_attr __user *u_mqstat,
1088			struct mq_attr __user *u_omqstat)
1089{
1090	int ret;
1091	struct mq_attr mqstat, omqstat;
1092	struct file *filp;
1093	struct inode *inode;
1094	struct mqueue_inode_info *info;
1095
1096	if (u_mqstat != NULL) {
1097		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1098			return -EFAULT;
1099		if (mqstat.mq_flags & (~O_NONBLOCK))
1100			return -EINVAL;
1101	}
1102
1103	ret = -EBADF;
1104	filp = fget(mqdes);
1105	if (!filp)
1106		goto out;
1107
1108	inode = filp->f_dentry->d_inode;
1109	if (unlikely(filp->f_op != &mqueue_file_operations))
1110		goto out_fput;
1111	info = MQUEUE_I(inode);
1112
1113	spin_lock(&info->lock);
1114
1115	omqstat = info->attr;
1116	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1117	if (u_mqstat) {
1118		if (mqstat.mq_flags & O_NONBLOCK)
1119			filp->f_flags |= O_NONBLOCK;
1120		else
1121			filp->f_flags &= ~O_NONBLOCK;
1122
1123		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1124	}
1125
1126	spin_unlock(&info->lock);
1127
1128	ret = 0;
1129	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1130						sizeof(struct mq_attr)))
1131		ret = -EFAULT;
1132
1133out_fput:
1134	fput(filp);
1135out:
1136	return ret;
1137}
1138
1139static struct inode_operations mqueue_dir_inode_operations = {
1140	.lookup = simple_lookup,
1141	.create = mqueue_create,
1142	.unlink = mqueue_unlink,
1143};
1144
1145static struct file_operations mqueue_file_operations = {
1146	.flush = mqueue_flush_file,
1147	.poll = mqueue_poll_file,
1148	.read = mqueue_read_file,
1149};
1150
1151static struct super_operations mqueue_super_ops = {
1152	.alloc_inode = mqueue_alloc_inode,
1153	.destroy_inode = mqueue_destroy_inode,
1154	.statfs = simple_statfs,
1155	.delete_inode = mqueue_delete_inode,
1156	.drop_inode = generic_delete_inode,
1157};
1158
1159static struct file_system_type mqueue_fs_type = {
1160	.name = "mqueue",
1161	.get_sb = mqueue_get_sb,
1162	.kill_sb = kill_litter_super,
1163};
1164
1165static int msg_max_limit_min = DFLT_MSGMAX;
1166static int msg_max_limit_max = HARD_MSGMAX;
1167
1168static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1169static int msg_maxsize_limit_max = INT_MAX;
1170
1171static ctl_table mq_sysctls[] = {
1172	{
1173		.ctl_name	= CTL_QUEUESMAX,
1174		.procname	= "queues_max",
1175		.data		= &queues_max,
1176		.maxlen		= sizeof(int),
1177		.mode		= 0644,
1178		.proc_handler	= &proc_dointvec,
1179	},
1180	{
1181		.ctl_name	= CTL_MSGMAX,
1182		.procname	= "msg_max",
1183		.data		= &msg_max,
1184		.maxlen		= sizeof(int),
1185		.mode		= 0644,
1186		.proc_handler	= &proc_dointvec_minmax,
1187		.extra1		= &msg_max_limit_min,
1188		.extra2		= &msg_max_limit_max,
1189	},
1190	{
1191		.ctl_name	= CTL_MSGSIZEMAX,
1192		.procname	= "msgsize_max",
1193		.data		= &msgsize_max,
1194		.maxlen		= sizeof(int),
1195		.mode		= 0644,
1196		.proc_handler	= &proc_dointvec_minmax,
1197		.extra1		= &msg_maxsize_limit_min,
1198		.extra2		= &msg_maxsize_limit_max,
1199	},
1200	{ .ctl_name = 0 }
1201};
1202
1203static ctl_table mq_sysctl_dir[] = {
1204	{
1205		.ctl_name	= FS_MQUEUE,
1206		.procname	= "mqueue",
1207		.mode		= 0555,
1208		.child		= mq_sysctls,
1209	},
1210	{ .ctl_name = 0 }
1211};
1212
1213static ctl_table mq_sysctl_root[] = {
1214	{
1215		.ctl_name	= CTL_FS,
1216		.procname	= "fs",
1217		.mode		= 0555,
1218		.child		= mq_sysctl_dir,
1219	},
1220	{ .ctl_name = 0 }
1221};
1222
1223static int __init init_mqueue_fs(void)
1224{
1225	int error;
1226
1227	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1228				sizeof(struct mqueue_inode_info), 0,
1229				SLAB_HWCACHE_ALIGN, init_once, NULL);
1230	if (mqueue_inode_cachep == NULL)
1231		return -ENOMEM;
1232
1233	/* ignore failues - they are not fatal */
1234	mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1235
1236	error = register_filesystem(&mqueue_fs_type);
1237	if (error)
1238		goto out_sysctl;
1239
1240	if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1241		error = PTR_ERR(mqueue_mnt);
1242		goto out_filesystem;
1243	}
1244
1245	/* internal initialization - not common for vfs */
1246	queues_count = 0;
1247	spin_lock_init(&mq_lock);
1248
1249	return 0;
1250
1251out_filesystem:
1252	unregister_filesystem(&mqueue_fs_type);
1253out_sysctl:
1254	if (mq_sysctl_table)
1255		unregister_sysctl_table(mq_sysctl_table);
1256	if (kmem_cache_destroy(mqueue_inode_cachep)) {
1257		printk(KERN_INFO
1258			"mqueue_inode_cache: not all structures were freed\n");
1259	}
1260	return error;
1261}
1262
1263__initcall(init_mqueue_fs);
1264