[PATCH] use smp_mb/wmb/rmb where possible
[linux-2.6.git] / ipc / mqueue.c
1 /*
2  * POSIX message queues filesystem for Linux.
3  *
4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5  *                          Michal Wronski          (wrona@mat.uni.torun.pl)
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/init.h>
15 #include <linux/pagemap.h>
16 #include <linux/file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include <linux/sysctl.h>
20 #include <linux/poll.h>
21 #include <linux/mqueue.h>
22 #include <linux/msg.h>
23 #include <linux/skbuff.h>
24 #include <linux/netlink.h>
25 #include <linux/syscalls.h>
26 #include <net/sock.h>
27 #include "util.h"
28
29 #define MQUEUE_MAGIC    0x19800202
30 #define DIRENT_SIZE     20
31 #define FILENT_SIZE     80
32
33 #define SEND            0
34 #define RECV            1
35
36 #define STATE_NONE      0
37 #define STATE_PENDING   1
38 #define STATE_READY     2
39
40 /* used by sysctl */
41 #define FS_MQUEUE       1
42 #define CTL_QUEUESMAX   2
43 #define CTL_MSGMAX      3
44 #define CTL_MSGSIZEMAX  4
45
46 /* default values */
47 #define DFLT_QUEUESMAX  256     /* max number of message queues */
48 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
49 #define HARD_MSGMAX     (131072/sizeof(void*))
50 #define DFLT_MSGSIZEMAX 8192    /* max message size */
51
52 #define NOTIFY_COOKIE_LEN       32
53
54 struct ext_wait_queue {         /* queue of sleeping tasks */
55         struct task_struct *task;
56         struct list_head list;
57         struct msg_msg *msg;    /* ptr of loaded message */
58         int state;              /* one of STATE_* values */
59 };
60
61 struct mqueue_inode_info {
62         spinlock_t lock;
63         struct inode vfs_inode;
64         wait_queue_head_t wait_q;
65
66         struct msg_msg **messages;
67         struct mq_attr attr;
68
69         struct sigevent notify;
70         pid_t notify_owner;
71         struct user_struct *user;       /* user who created, for accouting */
72         struct sock *notify_sock;
73         struct sk_buff *notify_cookie;
74
75         /* for tasks waiting for free space and messages, respectively */
76         struct ext_wait_queue e_wait_q[2];
77
78         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
79 };
80
81 static struct inode_operations mqueue_dir_inode_operations;
82 static struct file_operations mqueue_file_operations;
83 static struct super_operations mqueue_super_ops;
84 static void remove_notification(struct mqueue_inode_info *info);
85
86 static spinlock_t mq_lock;
87 static kmem_cache_t *mqueue_inode_cachep;
88 static struct vfsmount *mqueue_mnt;
89
90 static unsigned int queues_count;
91 static unsigned int queues_max  = DFLT_QUEUESMAX;
92 static unsigned int msg_max     = DFLT_MSGMAX;
93 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
94
95 static struct ctl_table_header * mq_sysctl_table;
96
97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
98 {
99         return container_of(inode, struct mqueue_inode_info, vfs_inode);
100 }
101
102 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
103                                                         struct mq_attr *attr)
104 {
105         struct inode *inode;
106
107         inode = new_inode(sb);
108         if (inode) {
109                 inode->i_mode = mode;
110                 inode->i_uid = current->fsuid;
111                 inode->i_gid = current->fsgid;
112                 inode->i_blksize = PAGE_CACHE_SIZE;
113                 inode->i_blocks = 0;
114                 inode->i_mtime = inode->i_ctime = inode->i_atime =
115                                 CURRENT_TIME;
116
117                 if (S_ISREG(mode)) {
118                         struct mqueue_inode_info *info;
119                         struct task_struct *p = current;
120                         struct user_struct *u = p->user;
121                         unsigned long mq_bytes, mq_msg_tblsz;
122
123                         inode->i_fop = &mqueue_file_operations;
124                         inode->i_size = FILENT_SIZE;
125                         /* mqueue specific info */
126                         info = MQUEUE_I(inode);
127                         spin_lock_init(&info->lock);
128                         init_waitqueue_head(&info->wait_q);
129                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
130                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
131                         info->messages = NULL;
132                         info->notify_owner = 0;
133                         info->qsize = 0;
134                         info->user = NULL;      /* set when all is ok */
135                         memset(&info->attr, 0, sizeof(info->attr));
136                         info->attr.mq_maxmsg = DFLT_MSGMAX;
137                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
138                         if (attr) {
139                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
140                                 info->attr.mq_msgsize = attr->mq_msgsize;
141                         }
142                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
143                         mq_bytes = (mq_msg_tblsz +
144                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
145
146                         spin_lock(&mq_lock);
147                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
148                             u->mq_bytes + mq_bytes >
149                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
150                                 spin_unlock(&mq_lock);
151                                 goto out_inode;
152                         }
153                         u->mq_bytes += mq_bytes;
154                         spin_unlock(&mq_lock);
155
156                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
157                         if (!info->messages) {
158                                 spin_lock(&mq_lock);
159                                 u->mq_bytes -= mq_bytes;
160                                 spin_unlock(&mq_lock);
161                                 goto out_inode;
162                         }
163                         /* all is ok */
164                         info->user = get_uid(u);
165                 } else if (S_ISDIR(mode)) {
166                         inode->i_nlink++;
167                         /* Some things misbehave if size == 0 on a directory */
168                         inode->i_size = 2 * DIRENT_SIZE;
169                         inode->i_op = &mqueue_dir_inode_operations;
170                         inode->i_fop = &simple_dir_operations;
171                 }
172         }
173         return inode;
174 out_inode:
175         make_bad_inode(inode);
176         iput(inode);
177         return NULL;
178 }
179
180 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
181 {
182         struct inode *inode;
183
184         sb->s_blocksize = PAGE_CACHE_SIZE;
185         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
186         sb->s_magic = MQUEUE_MAGIC;
187         sb->s_op = &mqueue_super_ops;
188
189         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
190         if (!inode)
191                 return -ENOMEM;
192
193         sb->s_root = d_alloc_root(inode);
194         if (!sb->s_root) {
195                 iput(inode);
196                 return -ENOMEM;
197         }
198
199         return 0;
200 }
201
202 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
203                                          int flags, const char *dev_name,
204                                          void *data)
205 {
206         return get_sb_single(fs_type, flags, data, mqueue_fill_super);
207 }
208
209 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
210 {
211         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
212
213         if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
214                 SLAB_CTOR_CONSTRUCTOR)
215                 inode_init_once(&p->vfs_inode);
216 }
217
218 static struct inode *mqueue_alloc_inode(struct super_block *sb)
219 {
220         struct mqueue_inode_info *ei;
221
222         ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
223         if (!ei)
224                 return NULL;
225         return &ei->vfs_inode;
226 }
227
228 static void mqueue_destroy_inode(struct inode *inode)
229 {
230         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
231 }
232
233 static void mqueue_delete_inode(struct inode *inode)
234 {
235         struct mqueue_inode_info *info;
236         struct user_struct *user;
237         unsigned long mq_bytes;
238         int i;
239
240         if (S_ISDIR(inode->i_mode)) {
241                 clear_inode(inode);
242                 return;
243         }
244         info = MQUEUE_I(inode);
245         spin_lock(&info->lock);
246         for (i = 0; i < info->attr.mq_curmsgs; i++)
247                 free_msg(info->messages[i]);
248         kfree(info->messages);
249         spin_unlock(&info->lock);
250
251         clear_inode(inode);
252
253         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
254                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
255         user = info->user;
256         if (user) {
257                 spin_lock(&mq_lock);
258                 user->mq_bytes -= mq_bytes;
259                 queues_count--;
260                 spin_unlock(&mq_lock);
261                 free_uid(user);
262         }
263 }
264
265 static int mqueue_create(struct inode *dir, struct dentry *dentry,
266                                 int mode, struct nameidata *nd)
267 {
268         struct inode *inode;
269         struct mq_attr *attr = dentry->d_fsdata;
270         int error;
271
272         spin_lock(&mq_lock);
273         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
274                 error = -ENOSPC;
275                 goto out_lock;
276         }
277         queues_count++;
278         spin_unlock(&mq_lock);
279
280         inode = mqueue_get_inode(dir->i_sb, mode, attr);
281         if (!inode) {
282                 error = -ENOMEM;
283                 spin_lock(&mq_lock);
284                 queues_count--;
285                 goto out_lock;
286         }
287
288         dir->i_size += DIRENT_SIZE;
289         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
290
291         d_instantiate(dentry, inode);
292         dget(dentry);
293         return 0;
294 out_lock:
295         spin_unlock(&mq_lock);
296         return error;
297 }
298
299 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
300 {
301         struct inode *inode = dentry->d_inode;
302
303         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
304         dir->i_size -= DIRENT_SIZE;
305         inode->i_nlink--;
306         dput(dentry);
307         return 0;
308 }
309
310 /*
311 *       This is routine for system read from queue file.
312 *       To avoid mess with doing here some sort of mq_receive we allow
313 *       to read only queue size & notification info (the only values
314 *       that are interesting from user point of view and aren't accessible
315 *       through std routines)
316 */
317 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
318                                 size_t count, loff_t * off)
319 {
320         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
321         char buffer[FILENT_SIZE];
322         size_t slen;
323         loff_t o;
324
325         if (!count)
326                 return 0;
327
328         spin_lock(&info->lock);
329         snprintf(buffer, sizeof(buffer),
330                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
331                         info->qsize,
332                         info->notify_owner ? info->notify.sigev_notify : 0,
333                         (info->notify_owner &&
334                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
335                                 info->notify.sigev_signo : 0,
336                         info->notify_owner);
337         spin_unlock(&info->lock);
338         buffer[sizeof(buffer)-1] = '\0';
339         slen = strlen(buffer)+1;
340
341         o = *off;
342         if (o > slen)
343                 return 0;
344
345         if (o + count > slen)
346                 count = slen - o;
347
348         if (copy_to_user(u_data, buffer + o, count))
349                 return -EFAULT;
350
351         *off = o + count;
352         filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
353         return count;
354 }
355
356 static int mqueue_flush_file(struct file *filp)
357 {
358         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
359
360         spin_lock(&info->lock);
361         if (current->tgid == info->notify_owner)
362                 remove_notification(info);
363
364         spin_unlock(&info->lock);
365         return 0;
366 }
367
368 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
369 {
370         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
371         int retval = 0;
372
373         poll_wait(filp, &info->wait_q, poll_tab);
374
375         spin_lock(&info->lock);
376         if (info->attr.mq_curmsgs)
377                 retval = POLLIN | POLLRDNORM;
378
379         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
380                 retval |= POLLOUT | POLLWRNORM;
381         spin_unlock(&info->lock);
382
383         return retval;
384 }
385
386 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
387 static void wq_add(struct mqueue_inode_info *info, int sr,
388                         struct ext_wait_queue *ewp)
389 {
390         struct ext_wait_queue *walk;
391
392         ewp->task = current;
393
394         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
395                 if (walk->task->static_prio <= current->static_prio) {
396                         list_add_tail(&ewp->list, &walk->list);
397                         return;
398                 }
399         }
400         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
401 }
402
403 /*
404  * Puts current task to sleep. Caller must hold queue lock. After return
405  * lock isn't held.
406  * sr: SEND or RECV
407  */
408 static int wq_sleep(struct mqueue_inode_info *info, int sr,
409                         long timeout, struct ext_wait_queue *ewp)
410 {
411         int retval;
412         signed long time;
413
414         wq_add(info, sr, ewp);
415
416         for (;;) {
417                 set_current_state(TASK_INTERRUPTIBLE);
418
419                 spin_unlock(&info->lock);
420                 time = schedule_timeout(timeout);
421
422                 while (ewp->state == STATE_PENDING)
423                         cpu_relax();
424
425                 if (ewp->state == STATE_READY) {
426                         retval = 0;
427                         goto out;
428                 }
429                 spin_lock(&info->lock);
430                 if (ewp->state == STATE_READY) {
431                         retval = 0;
432                         goto out_unlock;
433                 }
434                 if (signal_pending(current)) {
435                         retval = -ERESTARTSYS;
436                         break;
437                 }
438                 if (time == 0) {
439                         retval = -ETIMEDOUT;
440                         break;
441                 }
442         }
443         list_del(&ewp->list);
444 out_unlock:
445         spin_unlock(&info->lock);
446 out:
447         return retval;
448 }
449
450 /*
451  * Returns waiting task that should be serviced first or NULL if none exists
452  */
453 static struct ext_wait_queue *wq_get_first_waiter(
454                 struct mqueue_inode_info *info, int sr)
455 {
456         struct list_head *ptr;
457
458         ptr = info->e_wait_q[sr].list.prev;
459         if (ptr == &info->e_wait_q[sr].list)
460                 return NULL;
461         return list_entry(ptr, struct ext_wait_queue, list);
462 }
463
464 /* Auxiliary functions to manipulate messages' list */
465 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
466 {
467         int k;
468
469         k = info->attr.mq_curmsgs - 1;
470         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
471                 info->messages[k + 1] = info->messages[k];
472                 k--;
473         }
474         info->attr.mq_curmsgs++;
475         info->qsize += ptr->m_ts;
476         info->messages[k + 1] = ptr;
477 }
478
479 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
480 {
481         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
482         return info->messages[info->attr.mq_curmsgs];
483 }
484
485 static inline void set_cookie(struct sk_buff *skb, char code)
486 {
487         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
488 }
489
490 /*
491  * The next function is only to split too long sys_mq_timedsend
492  */
493 static void __do_notify(struct mqueue_inode_info *info)
494 {
495         /* notification
496          * invoked when there is registered process and there isn't process
497          * waiting synchronously for message AND state of queue changed from
498          * empty to not empty. Here we are sure that no one is waiting
499          * synchronously. */
500         if (info->notify_owner &&
501             info->attr.mq_curmsgs == 1) {
502                 struct siginfo sig_i;
503                 switch (info->notify.sigev_notify) {
504                 case SIGEV_NONE:
505                         break;
506                 case SIGEV_SIGNAL:
507                         /* sends signal */
508
509                         sig_i.si_signo = info->notify.sigev_signo;
510                         sig_i.si_errno = 0;
511                         sig_i.si_code = SI_MESGQ;
512                         sig_i.si_value = info->notify.sigev_value;
513                         sig_i.si_pid = current->tgid;
514                         sig_i.si_uid = current->uid;
515
516                         kill_proc_info(info->notify.sigev_signo,
517                                        &sig_i, info->notify_owner);
518                         break;
519                 case SIGEV_THREAD:
520                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
521                         netlink_sendskb(info->notify_sock,
522                                         info->notify_cookie, 0);
523                         break;
524                 }
525                 /* after notification unregisters process */
526                 info->notify_owner = 0;
527         }
528         wake_up(&info->wait_q);
529 }
530
531 static long prepare_timeout(const struct timespec __user *u_arg)
532 {
533         struct timespec ts, nowts;
534         long timeout;
535
536         if (u_arg) {
537                 if (unlikely(copy_from_user(&ts, u_arg,
538                                         sizeof(struct timespec))))
539                         return -EFAULT;
540
541                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
542                         || ts.tv_nsec >= NSEC_PER_SEC))
543                         return -EINVAL;
544                 nowts = CURRENT_TIME;
545                 /* first subtract as jiffies can't be too big */
546                 ts.tv_sec -= nowts.tv_sec;
547                 if (ts.tv_nsec < nowts.tv_nsec) {
548                         ts.tv_nsec += NSEC_PER_SEC;
549                         ts.tv_sec--;
550                 }
551                 ts.tv_nsec -= nowts.tv_nsec;
552                 if (ts.tv_sec < 0)
553                         return 0;
554
555                 timeout = timespec_to_jiffies(&ts) + 1;
556         } else
557                 return MAX_SCHEDULE_TIMEOUT;
558
559         return timeout;
560 }
561
562 static void remove_notification(struct mqueue_inode_info *info)
563 {
564         if (info->notify_owner != 0 &&
565             info->notify.sigev_notify == SIGEV_THREAD) {
566                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
567                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
568         }
569         info->notify_owner = 0;
570 }
571
572 static int mq_attr_ok(struct mq_attr *attr)
573 {
574         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
575                 return 0;
576         if (capable(CAP_SYS_RESOURCE)) {
577                 if (attr->mq_maxmsg > HARD_MSGMAX)
578                         return 0;
579         } else {
580                 if (attr->mq_maxmsg > msg_max ||
581                                 attr->mq_msgsize > msgsize_max)
582                         return 0;
583         }
584         /* check for overflow */
585         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
586                 return 0;
587         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
588             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
589             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
590                 return 0;
591         return 1;
592 }
593
594 /*
595  * Invoked when creating a new queue via sys_mq_open
596  */
597 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
598                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
599 {
600         struct file *filp;
601         struct mq_attr attr;
602         int ret;
603
604         if (u_attr != NULL) {
605                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
606                         return ERR_PTR(-EFAULT);
607                 if (!mq_attr_ok(&attr))
608                         return ERR_PTR(-EINVAL);
609                 /* store for use during create */
610                 dentry->d_fsdata = &attr;
611         }
612
613         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
614         dentry->d_fsdata = NULL;
615         if (ret)
616                 return ERR_PTR(ret);
617
618         filp = dentry_open(dentry, mqueue_mnt, oflag);
619         if (!IS_ERR(filp))
620                 dget(dentry);
621
622         return filp;
623 }
624
625 /* Opens existing queue */
626 static struct file *do_open(struct dentry *dentry, int oflag)
627 {
628 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
629                                         MAY_READ | MAY_WRITE };
630         struct file *filp;
631
632         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
633                 return ERR_PTR(-EINVAL);
634
635         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
636                 return ERR_PTR(-EACCES);
637
638         filp = dentry_open(dentry, mqueue_mnt, oflag);
639
640         if (!IS_ERR(filp))
641                 dget(dentry);
642
643         return filp;
644 }
645
646 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
647                                 struct mq_attr __user *u_attr)
648 {
649         struct dentry *dentry;
650         struct file *filp;
651         char *name;
652         int fd, error;
653
654         if (IS_ERR(name = getname(u_name)))
655                 return PTR_ERR(name);
656
657         fd = get_unused_fd();
658         if (fd < 0)
659                 goto out_putname;
660
661         down(&mqueue_mnt->mnt_root->d_inode->i_sem);
662         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
663         if (IS_ERR(dentry)) {
664                 error = PTR_ERR(dentry);
665                 goto out_err;
666         }
667         mntget(mqueue_mnt);
668
669         if (oflag & O_CREAT) {
670                 if (dentry->d_inode) {  /* entry already exists */
671                         filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
672                                         do_open(dentry, oflag);
673                 } else {
674                         filp = do_create(mqueue_mnt->mnt_root, dentry,
675                                                 oflag, mode, u_attr);
676                 }
677         } else
678                 filp = (dentry->d_inode) ? do_open(dentry, oflag) :
679                                         ERR_PTR(-ENOENT);
680
681         dput(dentry);
682
683         if (IS_ERR(filp)) {
684                 error = PTR_ERR(filp);
685                 goto out_putfd;
686         }
687
688         set_close_on_exec(fd, 1);
689         fd_install(fd, filp);
690         goto out_upsem;
691
692 out_putfd:
693         mntput(mqueue_mnt);
694         put_unused_fd(fd);
695 out_err:
696         fd = error;
697 out_upsem:
698         up(&mqueue_mnt->mnt_root->d_inode->i_sem);
699 out_putname:
700         putname(name);
701         return fd;
702 }
703
704 asmlinkage long sys_mq_unlink(const char __user *u_name)
705 {
706         int err;
707         char *name;
708         struct dentry *dentry;
709         struct inode *inode = NULL;
710
711         name = getname(u_name);
712         if (IS_ERR(name))
713                 return PTR_ERR(name);
714
715         down(&mqueue_mnt->mnt_root->d_inode->i_sem);
716         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
717         if (IS_ERR(dentry)) {
718                 err = PTR_ERR(dentry);
719                 goto out_unlock;
720         }
721
722         if (!dentry->d_inode) {
723                 err = -ENOENT;
724                 goto out_err;
725         }
726
727         inode = dentry->d_inode;
728         if (inode)
729                 atomic_inc(&inode->i_count);
730
731         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
732 out_err:
733         dput(dentry);
734
735 out_unlock:
736         up(&mqueue_mnt->mnt_root->d_inode->i_sem);
737         putname(name);
738         if (inode)
739                 iput(inode);
740
741         return err;
742 }
743
744 /* Pipelined send and receive functions.
745  *
746  * If a receiver finds no waiting message, then it registers itself in the
747  * list of waiting receivers. A sender checks that list before adding the new
748  * message into the message array. If there is a waiting receiver, then it
749  * bypasses the message array and directly hands the message over to the
750  * receiver.
751  * The receiver accepts the message and returns without grabbing the queue
752  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
753  * are necessary. The same algorithm is used for sysv semaphores, see
754  * ipc/sem.c fore more details.
755  *
756  * The same algorithm is used for senders.
757  */
758
759 /* pipelined_send() - send a message directly to the task waiting in
760  * sys_mq_timedreceive() (without inserting message into a queue).
761  */
762 static inline void pipelined_send(struct mqueue_inode_info *info,
763                                   struct msg_msg *message,
764                                   struct ext_wait_queue *receiver)
765 {
766         receiver->msg = message;
767         list_del(&receiver->list);
768         receiver->state = STATE_PENDING;
769         wake_up_process(receiver->task);
770         smp_wmb();
771         receiver->state = STATE_READY;
772 }
773
774 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
775  * gets its message and put to the queue (we have one free place for sure). */
776 static inline void pipelined_receive(struct mqueue_inode_info *info)
777 {
778         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
779
780         if (!sender) {
781                 /* for poll */
782                 wake_up_interruptible(&info->wait_q);
783                 return;
784         }
785         msg_insert(sender->msg, info);
786         list_del(&sender->list);
787         sender->state = STATE_PENDING;
788         wake_up_process(sender->task);
789         smp_wmb();
790         sender->state = STATE_READY;
791 }
792
793 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
794         size_t msg_len, unsigned int msg_prio,
795         const struct timespec __user *u_abs_timeout)
796 {
797         struct file *filp;
798         struct inode *inode;
799         struct ext_wait_queue wait;
800         struct ext_wait_queue *receiver;
801         struct msg_msg *msg_ptr;
802         struct mqueue_inode_info *info;
803         long timeout;
804         int ret;
805
806         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
807                 return -EINVAL;
808
809         timeout = prepare_timeout(u_abs_timeout);
810
811         ret = -EBADF;
812         filp = fget(mqdes);
813         if (unlikely(!filp))
814                 goto out;
815
816         inode = filp->f_dentry->d_inode;
817         if (unlikely(filp->f_op != &mqueue_file_operations))
818                 goto out_fput;
819         info = MQUEUE_I(inode);
820
821         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
822                 goto out_fput;
823
824         if (unlikely(msg_len > info->attr.mq_msgsize)) {
825                 ret = -EMSGSIZE;
826                 goto out_fput;
827         }
828
829         /* First try to allocate memory, before doing anything with
830          * existing queues. */
831         msg_ptr = load_msg(u_msg_ptr, msg_len);
832         if (IS_ERR(msg_ptr)) {
833                 ret = PTR_ERR(msg_ptr);
834                 goto out_fput;
835         }
836         msg_ptr->m_ts = msg_len;
837         msg_ptr->m_type = msg_prio;
838
839         spin_lock(&info->lock);
840
841         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
842                 if (filp->f_flags & O_NONBLOCK) {
843                         spin_unlock(&info->lock);
844                         ret = -EAGAIN;
845                 } else if (unlikely(timeout < 0)) {
846                         spin_unlock(&info->lock);
847                         ret = timeout;
848                 } else {
849                         wait.task = current;
850                         wait.msg = (void *) msg_ptr;
851                         wait.state = STATE_NONE;
852                         ret = wq_sleep(info, SEND, timeout, &wait);
853                 }
854                 if (ret < 0)
855                         free_msg(msg_ptr);
856         } else {
857                 receiver = wq_get_first_waiter(info, RECV);
858                 if (receiver) {
859                         pipelined_send(info, msg_ptr, receiver);
860                 } else {
861                         /* adds message to the queue */
862                         msg_insert(msg_ptr, info);
863                         __do_notify(info);
864                 }
865                 inode->i_atime = inode->i_mtime = inode->i_ctime =
866                                 CURRENT_TIME;
867                 spin_unlock(&info->lock);
868                 ret = 0;
869         }
870 out_fput:
871         fput(filp);
872 out:
873         return ret;
874 }
875
876 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
877         size_t msg_len, unsigned int __user *u_msg_prio,
878         const struct timespec __user *u_abs_timeout)
879 {
880         long timeout;
881         ssize_t ret;
882         struct msg_msg *msg_ptr;
883         struct file *filp;
884         struct inode *inode;
885         struct mqueue_inode_info *info;
886         struct ext_wait_queue wait;
887
888         timeout = prepare_timeout(u_abs_timeout);
889
890         ret = -EBADF;
891         filp = fget(mqdes);
892         if (unlikely(!filp))
893                 goto out;
894
895         inode = filp->f_dentry->d_inode;
896         if (unlikely(filp->f_op != &mqueue_file_operations))
897                 goto out_fput;
898         info = MQUEUE_I(inode);
899
900         if (unlikely(!(filp->f_mode & FMODE_READ)))
901                 goto out_fput;
902
903         /* checks if buffer is big enough */
904         if (unlikely(msg_len < info->attr.mq_msgsize)) {
905                 ret = -EMSGSIZE;
906                 goto out_fput;
907         }
908
909         spin_lock(&info->lock);
910         if (info->attr.mq_curmsgs == 0) {
911                 if (filp->f_flags & O_NONBLOCK) {
912                         spin_unlock(&info->lock);
913                         ret = -EAGAIN;
914                         msg_ptr = NULL;
915                 } else if (unlikely(timeout < 0)) {
916                         spin_unlock(&info->lock);
917                         ret = timeout;
918                         msg_ptr = NULL;
919                 } else {
920                         wait.task = current;
921                         wait.state = STATE_NONE;
922                         ret = wq_sleep(info, RECV, timeout, &wait);
923                         msg_ptr = wait.msg;
924                 }
925         } else {
926                 msg_ptr = msg_get(info);
927
928                 inode->i_atime = inode->i_mtime = inode->i_ctime =
929                                 CURRENT_TIME;
930
931                 /* There is now free space in queue. */
932                 pipelined_receive(info);
933                 spin_unlock(&info->lock);
934                 ret = 0;
935         }
936         if (ret == 0) {
937                 ret = msg_ptr->m_ts;
938
939                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
940                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
941                         ret = -EFAULT;
942                 }
943                 free_msg(msg_ptr);
944         }
945 out_fput:
946         fput(filp);
947 out:
948         return ret;
949 }
950
951 /*
952  * Notes: the case when user wants us to deregister (with NULL as pointer)
953  * and he isn't currently owner of notification, will be silently discarded.
954  * It isn't explicitly defined in the POSIX.
955  */
956 asmlinkage long sys_mq_notify(mqd_t mqdes,
957                                 const struct sigevent __user *u_notification)
958 {
959         int ret;
960         struct file *filp;
961         struct sock *sock;
962         struct inode *inode;
963         struct sigevent notification;
964         struct mqueue_inode_info *info;
965         struct sk_buff *nc;
966
967         nc = NULL;
968         sock = NULL;
969         if (u_notification != NULL) {
970                 if (copy_from_user(&notification, u_notification,
971                                         sizeof(struct sigevent)))
972                         return -EFAULT;
973
974                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
975                              notification.sigev_notify != SIGEV_SIGNAL &&
976                              notification.sigev_notify != SIGEV_THREAD))
977                         return -EINVAL;
978                 if (notification.sigev_notify == SIGEV_SIGNAL &&
979                         (notification.sigev_signo < 0 ||
980                          notification.sigev_signo > _NSIG)) {
981                         return -EINVAL;
982                 }
983                 if (notification.sigev_notify == SIGEV_THREAD) {
984                         /* create the notify skb */
985                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
986                         ret = -ENOMEM;
987                         if (!nc)
988                                 goto out;
989                         ret = -EFAULT;
990                         if (copy_from_user(nc->data,
991                                         notification.sigev_value.sival_ptr,
992                                         NOTIFY_COOKIE_LEN)) {
993                                 goto out;
994                         }
995
996                         /* TODO: add a header? */
997                         skb_put(nc, NOTIFY_COOKIE_LEN);
998                         /* and attach it to the socket */
999 retry:
1000                         filp = fget(notification.sigev_signo);
1001                         ret = -EBADF;
1002                         if (!filp)
1003                                 goto out;
1004                         sock = netlink_getsockbyfilp(filp);
1005                         fput(filp);
1006                         if (IS_ERR(sock)) {
1007                                 ret = PTR_ERR(sock);
1008                                 sock = NULL;
1009                                 goto out;
1010                         }
1011
1012                         ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
1013                         if (ret == 1)
1014                                 goto retry;
1015                         if (ret) {
1016                                 sock = NULL;
1017                                 nc = NULL;
1018                                 goto out;
1019                         }
1020                 }
1021         }
1022
1023         ret = -EBADF;
1024         filp = fget(mqdes);
1025         if (!filp)
1026                 goto out;
1027
1028         inode = filp->f_dentry->d_inode;
1029         if (unlikely(filp->f_op != &mqueue_file_operations))
1030                 goto out_fput;
1031         info = MQUEUE_I(inode);
1032
1033         ret = 0;
1034         spin_lock(&info->lock);
1035         if (u_notification == NULL) {
1036                 if (info->notify_owner == current->tgid) {
1037                         remove_notification(info);
1038                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1039                 }
1040         } else if (info->notify_owner != 0) {
1041                 ret = -EBUSY;
1042         } else {
1043                 switch (notification.sigev_notify) {
1044                 case SIGEV_NONE:
1045                         info->notify.sigev_notify = SIGEV_NONE;
1046                         break;
1047                 case SIGEV_THREAD:
1048                         info->notify_sock = sock;
1049                         info->notify_cookie = nc;
1050                         sock = NULL;
1051                         nc = NULL;
1052                         info->notify.sigev_notify = SIGEV_THREAD;
1053                         break;
1054                 case SIGEV_SIGNAL:
1055                         info->notify.sigev_signo = notification.sigev_signo;
1056                         info->notify.sigev_value = notification.sigev_value;
1057                         info->notify.sigev_notify = SIGEV_SIGNAL;
1058                         break;
1059                 }
1060                 info->notify_owner = current->tgid;
1061                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1062         }
1063         spin_unlock(&info->lock);
1064 out_fput:
1065         fput(filp);
1066 out:
1067         if (sock) {
1068                 netlink_detachskb(sock, nc);
1069         } else if (nc) {
1070                 dev_kfree_skb(nc);
1071         }
1072         return ret;
1073 }
1074
1075 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1076                         const struct mq_attr __user *u_mqstat,
1077                         struct mq_attr __user *u_omqstat)
1078 {
1079         int ret;
1080         struct mq_attr mqstat, omqstat;
1081         struct file *filp;
1082         struct inode *inode;
1083         struct mqueue_inode_info *info;
1084
1085         if (u_mqstat != NULL) {
1086                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1087                         return -EFAULT;
1088                 if (mqstat.mq_flags & (~O_NONBLOCK))
1089                         return -EINVAL;
1090         }
1091
1092         ret = -EBADF;
1093         filp = fget(mqdes);
1094         if (!filp)
1095                 goto out;
1096
1097         inode = filp->f_dentry->d_inode;
1098         if (unlikely(filp->f_op != &mqueue_file_operations))
1099                 goto out_fput;
1100         info = MQUEUE_I(inode);
1101
1102         spin_lock(&info->lock);
1103
1104         omqstat = info->attr;
1105         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1106         if (u_mqstat) {
1107                 if (mqstat.mq_flags & O_NONBLOCK)
1108                         filp->f_flags |= O_NONBLOCK;
1109                 else
1110                         filp->f_flags &= ~O_NONBLOCK;
1111
1112                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1113         }
1114
1115         spin_unlock(&info->lock);
1116
1117         ret = 0;
1118         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1119                                                 sizeof(struct mq_attr)))
1120                 ret = -EFAULT;
1121
1122 out_fput:
1123         fput(filp);
1124 out:
1125         return ret;
1126 }
1127
1128 static struct inode_operations mqueue_dir_inode_operations = {
1129         .lookup = simple_lookup,
1130         .create = mqueue_create,
1131         .unlink = mqueue_unlink,
1132 };
1133
1134 static struct file_operations mqueue_file_operations = {
1135         .flush = mqueue_flush_file,
1136         .poll = mqueue_poll_file,
1137         .read = mqueue_read_file,
1138 };
1139
1140 static struct super_operations mqueue_super_ops = {
1141         .alloc_inode = mqueue_alloc_inode,
1142         .destroy_inode = mqueue_destroy_inode,
1143         .statfs = simple_statfs,
1144         .delete_inode = mqueue_delete_inode,
1145         .drop_inode = generic_delete_inode,
1146 };
1147
1148 static struct file_system_type mqueue_fs_type = {
1149         .name = "mqueue",
1150         .get_sb = mqueue_get_sb,
1151         .kill_sb = kill_litter_super,
1152 };
1153
1154 static int msg_max_limit_min = DFLT_MSGMAX;
1155 static int msg_max_limit_max = HARD_MSGMAX;
1156
1157 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1158 static int msg_maxsize_limit_max = INT_MAX;
1159
1160 static ctl_table mq_sysctls[] = {
1161         {
1162                 .ctl_name       = CTL_QUEUESMAX,
1163                 .procname       = "queues_max",
1164                 .data           = &queues_max,
1165                 .maxlen         = sizeof(int),
1166                 .mode           = 0644,
1167                 .proc_handler   = &proc_dointvec,
1168         },
1169         {
1170                 .ctl_name       = CTL_MSGMAX,
1171                 .procname       = "msg_max",
1172                 .data           = &msg_max,
1173                 .maxlen         = sizeof(int),
1174                 .mode           = 0644,
1175                 .proc_handler   = &proc_dointvec_minmax,
1176                 .extra1         = &msg_max_limit_min,
1177                 .extra2         = &msg_max_limit_max,
1178         },
1179         {
1180                 .ctl_name       = CTL_MSGSIZEMAX,
1181                 .procname       = "msgsize_max",
1182                 .data           = &msgsize_max,
1183                 .maxlen         = sizeof(int),
1184                 .mode           = 0644,
1185                 .proc_handler   = &proc_dointvec_minmax,
1186                 .extra1         = &msg_maxsize_limit_min,
1187                 .extra2         = &msg_maxsize_limit_max,
1188         },
1189         { .ctl_name = 0 }
1190 };
1191
1192 static ctl_table mq_sysctl_dir[] = {
1193         {
1194                 .ctl_name       = FS_MQUEUE,
1195                 .procname       = "mqueue",
1196                 .mode           = 0555,
1197                 .child          = mq_sysctls,
1198         },
1199         { .ctl_name = 0 }
1200 };
1201
1202 static ctl_table mq_sysctl_root[] = {
1203         {
1204                 .ctl_name       = CTL_FS,
1205                 .procname       = "fs",
1206                 .mode           = 0555,
1207                 .child          = mq_sysctl_dir,
1208         },
1209         { .ctl_name = 0 }
1210 };
1211
1212 static int __init init_mqueue_fs(void)
1213 {
1214         int error;
1215
1216         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1217                                 sizeof(struct mqueue_inode_info), 0,
1218                                 SLAB_HWCACHE_ALIGN, init_once, NULL);
1219         if (mqueue_inode_cachep == NULL)
1220                 return -ENOMEM;
1221
1222         /* ignore failues - they are not fatal */
1223         mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1224
1225         error = register_filesystem(&mqueue_fs_type);
1226         if (error)
1227                 goto out_sysctl;
1228
1229         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1230                 error = PTR_ERR(mqueue_mnt);
1231                 goto out_filesystem;
1232         }
1233
1234         /* internal initialization - not common for vfs */
1235         queues_count = 0;
1236         spin_lock_init(&mq_lock);
1237
1238         return 0;
1239
1240 out_filesystem:
1241         unregister_filesystem(&mqueue_fs_type);
1242 out_sysctl:
1243         if (mq_sysctl_table)
1244                 unregister_sysctl_table(mq_sysctl_table);
1245         if (kmem_cache_destroy(mqueue_inode_cachep)) {
1246                 printk(KERN_INFO
1247                         "mqueue_inode_cache: not all structures were freed\n");
1248         }
1249         return error;
1250 }
1251
1252 __initcall(init_mqueue_fs);