[PATCH] unify pfn_to_page: mips pfn_to_page
[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          (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
57 struct 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
64 struct 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
84 static struct inode_operations mqueue_dir_inode_operations;
85 static struct file_operations mqueue_file_operations;
86 static struct super_operations mqueue_super_ops;
87 static void remove_notification(struct mqueue_inode_info *info);
88
89 static spinlock_t mq_lock;
90 static kmem_cache_t *mqueue_inode_cachep;
91 static struct vfsmount *mqueue_mnt;
92
93 static unsigned int queues_count;
94 static unsigned int queues_max  = DFLT_QUEUESMAX;
95 static unsigned int msg_max     = DFLT_MSGMAX;
96 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
97
98 static struct ctl_table_header * mq_sysctl_table;
99
100 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
101 {
102         return container_of(inode, struct mqueue_inode_info, vfs_inode);
103 }
104
105 static 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;
177 out_inode:
178         make_bad_inode(inode);
179         iput(inode);
180         return NULL;
181 }
182
183 static 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
205 static 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
212 static 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
221 static 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
231 static void mqueue_destroy_inode(struct inode *inode)
232 {
233         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
234 }
235
236 static 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
268 static 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;
297 out_lock:
298         spin_unlock(&mq_lock);
299         return error;
300 }
301
302 static 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 */
320 static 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
359 static 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
371 static 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 */
390 static 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  */
411 static 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);
447 out_unlock:
448         spin_unlock(&info->lock);
449 out:
450         return retval;
451 }
452
453 /*
454  * Returns waiting task that should be serviced first or NULL if none exists
455  */
456 static 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 */
468 static 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
482 static 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
488 static 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  */
496 static 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
534 static 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
565 static 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
575 static 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  */
600 static 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
625 out:
626         dput(dentry);
627         mntput(mqueue_mnt);
628         return ERR_PTR(ret);
629 }
630
631 /* Opens existing queue */
632 static struct file *do_open(struct dentry *dentry, int oflag)
633 {
634 static 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
652 asmlinkage 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
701 out:
702         dput(dentry);
703         mntput(mqueue_mnt);
704 out_putfd:
705         put_unused_fd(fd);
706 out_err:
707         fd = error;
708 out_upsem:
709         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
710 out_putname:
711         putname(name);
712         return fd;
713 }
714
715 asmlinkage 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);
743 out_err:
744         dput(dentry);
745
746 out_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 fore 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  */
773 static 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). */
787 static 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
804 asmlinkage 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         }
881 out_fput:
882         fput(filp);
883 out:
884         return ret;
885 }
886
887 asmlinkage 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         }
956 out_fput:
957         fput(filp);
958 out:
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  */
967 asmlinkage 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 */
1009 retry:
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);
1075 out_fput:
1076         fput(filp);
1077 out:
1078         if (sock) {
1079                 netlink_detachskb(sock, nc);
1080         } else if (nc) {
1081                 dev_kfree_skb(nc);
1082         }
1083         return ret;
1084 }
1085
1086 asmlinkage 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
1133 out_fput:
1134         fput(filp);
1135 out:
1136         return ret;
1137 }
1138
1139 static struct inode_operations mqueue_dir_inode_operations = {
1140         .lookup = simple_lookup,
1141         .create = mqueue_create,
1142         .unlink = mqueue_unlink,
1143 };
1144
1145 static struct file_operations mqueue_file_operations = {
1146         .flush = mqueue_flush_file,
1147         .poll = mqueue_poll_file,
1148         .read = mqueue_read_file,
1149 };
1150
1151 static 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
1159 static struct file_system_type mqueue_fs_type = {
1160         .name = "mqueue",
1161         .get_sb = mqueue_get_sb,
1162         .kill_sb = kill_litter_super,
1163 };
1164
1165 static int msg_max_limit_min = DFLT_MSGMAX;
1166 static int msg_max_limit_max = HARD_MSGMAX;
1167
1168 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1169 static int msg_maxsize_limit_max = INT_MAX;
1170
1171 static 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
1203 static 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
1213 static 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
1223 static 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
1251 out_filesystem:
1252         unregister_filesystem(&mqueue_fs_type);
1253 out_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);