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initial commit with v2.6.9
[linux-2.6.9-moxart.git] / ipc / mqueue.c
blobaee2696c30b1efdd6c549e01998a72a496a7972d
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 <net/sock.h>
26 #include "util.h"
27
28 #define MQUEUE_MAGIC 0x19800202
29 #define DIRENT_SIZE 20
30 #define FILENT_SIZE 80
31
32 #define SEND 0
33 #define RECV 1
34
35 #define STATE_NONE 0
36 #define STATE_PENDING 1
37 #define STATE_READY 2
38
39 /* used by sysctl */
40 #define FS_MQUEUE 1
41 #define CTL_QUEUESMAX 2
42 #define CTL_MSGMAX 3
43 #define CTL_MSGSIZEMAX 4
44
45 /* default values */
46 #define DFLT_QUEUESMAX 256 /* max number of message queues */
47 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
48 #define HARD_MSGMAX (131072/sizeof(void*))
49 #define DFLT_MSGSIZEMAX 8192 /* max message size */
50
51 #define NOTIFY_COOKIE_LEN 32
52
53 struct ext_wait_queue { /* queue of sleeping tasks */
54 struct task_struct *task;
55 struct list_head list;
56 struct msg_msg *msg; /* ptr of loaded message */
57 int state; /* one of STATE_* values */
58 };
59
60 struct mqueue_inode_info {
61 spinlock_t lock;
62 struct inode vfs_inode;
63 wait_queue_head_t wait_q;
64
65 struct msg_msg **messages;
66 struct mq_attr attr;
67
68 struct sigevent notify;
69 pid_t notify_owner;
70 struct user_struct *user; /* user who created, for accouting */
71 struct sock *notify_sock;
72 struct sk_buff *notify_cookie;
73
74 /* for tasks waiting for free space and messages, respectively */
75 struct ext_wait_queue e_wait_q[2];
76
77 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
78 };
79
80 static struct inode_operations mqueue_dir_inode_operations;
81 static struct file_operations mqueue_file_operations;
82 static struct super_operations mqueue_super_ops;
83 static void remove_notification(struct mqueue_inode_info *info);
84
85 static spinlock_t mq_lock;
86 static kmem_cache_t *mqueue_inode_cachep;
87 static struct vfsmount *mqueue_mnt;
88
89 static unsigned int queues_count;
90 static unsigned int queues_max = DFLT_QUEUESMAX;
91 static unsigned int msg_max = DFLT_MSGMAX;
92 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
93
94 static struct ctl_table_header * mq_sysctl_table;
95
96 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
97 {
98 return container_of(inode, struct mqueue_inode_info, vfs_inode);
99 }
100
101 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
102 struct mq_attr *attr)
103 {
104 struct inode *inode;
105
106 inode = new_inode(sb);
107 if (inode) {
108 inode->i_mode = mode;
109 inode->i_uid = current->fsuid;
110 inode->i_gid = current->fsgid;
111 inode->i_blksize = PAGE_CACHE_SIZE;
112 inode->i_blocks = 0;
113 inode->i_mtime = inode->i_ctime = inode->i_atime =
114 CURRENT_TIME;
115
116 if (S_ISREG(mode)) {
117 struct mqueue_inode_info *info;
118 struct task_struct *p = current;
119 struct user_struct *u = p->user;
120 unsigned long mq_bytes, mq_msg_tblsz;
121
122 inode->i_fop = &mqueue_file_operations;
123 inode->i_size = FILENT_SIZE;
124 /* mqueue specific info */
125 info = MQUEUE_I(inode);
126 spin_lock_init(&info->lock);
127 init_waitqueue_head(&info->wait_q);
128 INIT_LIST_HEAD(&info->e_wait_q[0].list);
129 INIT_LIST_HEAD(&info->e_wait_q[1].list);
130 info->messages = NULL;
131 info->notify_owner = 0;
132 info->qsize = 0;
133 info->user = NULL; /* set when all is ok */
134 memset(&info->attr, 0, sizeof(info->attr));
135 info->attr.mq_maxmsg = DFLT_MSGMAX;
136 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
137 if (attr) {
138 info->attr.mq_maxmsg = attr->mq_maxmsg;
139 info->attr.mq_msgsize = attr->mq_msgsize;
140 }
141 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
142 mq_bytes = (mq_msg_tblsz +
143 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
144
145 spin_lock(&mq_lock);
146 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
147 u->mq_bytes + mq_bytes >
148 p->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
149 spin_unlock(&mq_lock);
150 goto out_inode;
151 }
152 u->mq_bytes += mq_bytes;
153 spin_unlock(&mq_lock);
154
155 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
156 if (!info->messages) {
157 spin_lock(&mq_lock);
158 u->mq_bytes -= mq_bytes;
159 spin_unlock(&mq_lock);
160 goto out_inode;
161 }
162 /* all is ok */
163 info->user = get_uid(u);
164 } else if (S_ISDIR(mode)) {
165 inode->i_nlink++;
166 /* Some things misbehave if size == 0 on a directory */
167 inode->i_size = 2 * DIRENT_SIZE;
168 inode->i_op = &mqueue_dir_inode_operations;
169 inode->i_fop = &simple_dir_operations;
170 }
171 }
172 return inode;
173 out_inode:
174 make_bad_inode(inode);
175 iput(inode);
176 return NULL;
177 }
178
179 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
180 {
181 struct inode *inode;
182
183 sb->s_blocksize = PAGE_CACHE_SIZE;
184 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
185 sb->s_magic = MQUEUE_MAGIC;
186 sb->s_op = &mqueue_super_ops;
187
188 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
189 if (!inode)
190 return -ENOMEM;
191
192 sb->s_root = d_alloc_root(inode);
193 if (!sb->s_root) {
194 iput(inode);
195 return -ENOMEM;
196 }
197
198 return 0;
199 }
200
201 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
202 int flags, const char *dev_name,
203 void *data)
204 {
205 return get_sb_single(fs_type, flags, data, mqueue_fill_super);
206 }
207
208 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
209 {
210 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
211
212 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
213 SLAB_CTOR_CONSTRUCTOR)
214 inode_init_once(&p->vfs_inode);
215 }
216
217 static struct inode *mqueue_alloc_inode(struct super_block *sb)
218 {
219 struct mqueue_inode_info *ei;
220
221 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
222 if (!ei)
223 return NULL;
224 return &ei->vfs_inode;
225 }
226
227 static void mqueue_destroy_inode(struct inode *inode)
228 {
229 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
230 }
231
232 static void mqueue_delete_inode(struct inode *inode)
233 {
234 struct mqueue_inode_info *info;
235 struct user_struct *user;
236 unsigned long mq_bytes;
237 int i;
238
239 if (S_ISDIR(inode->i_mode)) {
240 clear_inode(inode);
241 return;
242 }
243 info = MQUEUE_I(inode);
244 spin_lock(&info->lock);
245 for (i = 0; i < info->attr.mq_curmsgs; i++)
246 free_msg(info->messages[i]);
247 kfree(info->messages);
248 spin_unlock(&info->lock);
249
250 clear_inode(inode);
251
252 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
253 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
254 user = info->user;
255 if (user) {
256 spin_lock(&mq_lock);
257 user->mq_bytes -= mq_bytes;
258 queues_count--;
259 spin_unlock(&mq_lock);
260 free_uid(user);
261 }
262 }
263
264 static int mqueue_create(struct inode *dir, struct dentry *dentry,
265 int mode, struct nameidata *nd)
266 {
267 struct inode *inode;
268 struct mq_attr *attr = dentry->d_fsdata;
269 int error;
270
271 spin_lock(&mq_lock);
272 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
273 error = -ENOSPC;
274 goto out_lock;
275 }
276 queues_count++;
277 spin_unlock(&mq_lock);
278
279 inode = mqueue_get_inode(dir->i_sb, mode, attr);
280 if (!inode) {
281 error = -ENOMEM;
282 spin_lock(&mq_lock);
283 queues_count--;
284 goto out_lock;
285 }
286
287 dir->i_size += DIRENT_SIZE;
288 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
289
290 d_instantiate(dentry, inode);
291 dget(dentry);
292 return 0;
293 out_lock:
294 spin_unlock(&mq_lock);
295 return error;
296 }
297
298 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
299 {
300 struct inode *inode = dentry->d_inode;
301
302 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
303 dir->i_size -= DIRENT_SIZE;
304 inode->i_nlink--;
305 dput(dentry);
306 return 0;
307 }
308
309 /*
310 * This is routine for system read from queue file.
311 * To avoid mess with doing here some sort of mq_receive we allow
312 * to read only queue size & notification info (the only values
313 * that are interesting from user point of view and aren't accessible
314 * through std routines)
315 */
316 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
317 size_t count, loff_t * off)
318 {
319 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
320 char buffer[FILENT_SIZE];
321 size_t slen;
322 loff_t o;
323
324 if (!count)
325 return 0;
326
327 spin_lock(&info->lock);
328 snprintf(buffer, sizeof(buffer),
329 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
330 info->qsize,
331 info->notify_owner ? info->notify.sigev_notify : 0,
332 (info->notify_owner &&
333 info->notify.sigev_notify == SIGEV_SIGNAL) ?
334 info->notify.sigev_signo : 0,
335 info->notify_owner);
336 spin_unlock(&info->lock);
337 buffer[sizeof(buffer)-1] = '\0';
338 slen = strlen(buffer)+1;
339
340 o = *off;
341 if (o > slen)
342 return 0;
343
344 if (o + count > slen)
345 count = slen - o;
346
347 if (copy_to_user(u_data, buffer + o, count))
348 return -EFAULT;
349
350 *off = o + count;
351 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
352 return count;
353 }
354
355 static int mqueue_flush_file(struct file *filp)
356 {
357 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
358
359 spin_lock(&info->lock);
360 if (current->tgid == info->notify_owner)
361 remove_notification(info);
362
363 spin_unlock(&info->lock);
364 return 0;
365 }
366
367 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
368 {
369 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
370 int retval = 0;
371
372 poll_wait(filp, &info->wait_q, poll_tab);
373
374 spin_lock(&info->lock);
375 if (info->attr.mq_curmsgs)
376 retval = POLLIN | POLLRDNORM;
377
378 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
379 retval |= POLLOUT | POLLWRNORM;
380 spin_unlock(&info->lock);
381
382 return retval;
383 }
384
385 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
386 static void wq_add(struct mqueue_inode_info *info, int sr,
387 struct ext_wait_queue *ewp)
388 {
389 struct ext_wait_queue *walk;
390
391 ewp->task = current;
392
393 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
394 if (walk->task->static_prio <= current->static_prio) {
395 list_add_tail(&ewp->list, &walk->list);
396 return;
397 }
398 }
399 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
400 }
401
402 /*
403 * Puts current task to sleep. Caller must hold queue lock. After return
404 * lock isn't held.
405 * sr: SEND or RECV
406 */
407 static int wq_sleep(struct mqueue_inode_info *info, int sr,
408 long timeout, struct ext_wait_queue *ewp)
409 {
410 int retval;
411 signed long time;
412
413 wq_add(info, sr, ewp);
414
415 for (;;) {
416 set_current_state(TASK_INTERRUPTIBLE);
417
418 spin_unlock(&info->lock);
419 time = schedule_timeout(timeout);
420
421 while (ewp->state == STATE_PENDING)
422 cpu_relax();
423
424 if (ewp->state == STATE_READY) {
425 retval = 0;
426 goto out;
427 }
428 spin_lock(&info->lock);
429 if (ewp->state == STATE_READY) {
430 retval = 0;
431 goto out_unlock;
432 }
433 if (signal_pending(current)) {
434 retval = -ERESTARTSYS;
435 break;
436 }
437 if (time == 0) {
438 retval = -ETIMEDOUT;
439 break;
440 }
441 }
442 list_del(&ewp->list);
443 out_unlock:
444 spin_unlock(&info->lock);
445 out:
446 return retval;
447 }
448
449 /*
450 * Returns waiting task that should be serviced first or NULL if none exists
451 */
452 static struct ext_wait_queue *wq_get_first_waiter(
453 struct mqueue_inode_info *info, int sr)
454 {
455 struct list_head *ptr;
456
457 ptr = info->e_wait_q[sr].list.prev;
458 if (ptr == &info->e_wait_q[sr].list)
459 return NULL;
460 return list_entry(ptr, struct ext_wait_queue, list);
461 }
462
463 /* Auxiliary functions to manipulate messages' list */
464 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
465 {
466 int k;
467
468 k = info->attr.mq_curmsgs - 1;
469 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
470 info->messages[k + 1] = info->messages[k];
471 k--;
472 }
473 info->attr.mq_curmsgs++;
474 info->qsize += ptr->m_ts;
475 info->messages[k + 1] = ptr;
476 }
477
478 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
479 {
480 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
481 return info->messages[info->attr.mq_curmsgs];
482 }
483
484 static inline void set_cookie(struct sk_buff *skb, char code)
485 {
486 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
487 }
488
489 /*
490 * The next function is only to split too long sys_mq_timedsend
491 */
492 static void __do_notify(struct mqueue_inode_info *info)
493 {
494 /* notification
495 * invoked when there is registered process and there isn't process
496 * waiting synchronously for message AND state of queue changed from
497 * empty to not empty. Here we are sure that no one is waiting
498 * synchronously. */
499 if (info->notify_owner &&
500 info->attr.mq_curmsgs == 1) {
501 struct siginfo sig_i;
502 switch (info->notify.sigev_notify) {
503 case SIGEV_NONE:
504 break;
505 case SIGEV_SIGNAL:
506 /* sends signal */
507
508 sig_i.si_signo = info->notify.sigev_signo;
509 sig_i.si_errno = 0;
510 sig_i.si_code = SI_MESGQ;
511 sig_i.si_value = info->notify.sigev_value;
512 sig_i.si_pid = current->tgid;
513 sig_i.si_uid = current->uid;
514
515 kill_proc_info(info->notify.sigev_signo,
516 &sig_i, info->notify_owner);
517 break;
518 case SIGEV_THREAD:
519 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
520 netlink_sendskb(info->notify_sock,
521 info->notify_cookie, 0);
522 break;
523 }
524 /* after notification unregisters process */
525 info->notify_owner = 0;
526 }
527 wake_up(&info->wait_q);
528 }
529
530 static long prepare_timeout(const struct timespec __user *u_arg)
531 {
532 struct timespec ts, nowts;
533 long timeout;
534
535 if (u_arg) {
536 if (unlikely(copy_from_user(&ts, u_arg,
537 sizeof(struct timespec))))
538 return -EFAULT;
539
540 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
541 || ts.tv_nsec >= NSEC_PER_SEC))
542 return -EINVAL;
543 nowts = CURRENT_TIME;
544 /* first subtract as jiffies can't be too big */
545 ts.tv_sec -= nowts.tv_sec;
546 if (ts.tv_nsec < nowts.tv_nsec) {
547 ts.tv_nsec += NSEC_PER_SEC;
548 ts.tv_sec--;
549 }
550 ts.tv_nsec -= nowts.tv_nsec;
551 if (ts.tv_sec < 0)
552 return 0;
553
554 timeout = timespec_to_jiffies(&ts) + 1;
555 } else
556 return MAX_SCHEDULE_TIMEOUT;
557
558 return timeout;
559 }
560
561 static void remove_notification(struct mqueue_inode_info *info)
562 {
563 if (info->notify_owner != 0 &&
564 info->notify.sigev_notify == SIGEV_THREAD) {
565 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
566 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
567 }
568 info->notify_owner = 0;
569 }
570
571 static int mq_attr_ok(struct mq_attr *attr)
572 {
573 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
574 return 0;
575 if (capable(CAP_SYS_RESOURCE)) {
576 if (attr->mq_maxmsg > HARD_MSGMAX)
577 return 0;
578 } else {
579 if (attr->mq_maxmsg > msg_max ||
580 attr->mq_msgsize > msgsize_max)
581 return 0;
582 }
583 /* check for overflow */
584 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
585 return 0;
586 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
587 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
588 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
589 return 0;
590 return 1;
591 }
592
593 /*
594 * Invoked when creating a new queue via sys_mq_open
595 */
596 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
597 int oflag, mode_t mode, struct mq_attr __user *u_attr)
598 {
599 struct file *filp;
600 struct mq_attr attr;
601 int ret;
602
603 if (u_attr != NULL) {
604 if (copy_from_user(&attr, u_attr, sizeof(attr)))
605 return ERR_PTR(-EFAULT);
606 if (!mq_attr_ok(&attr))
607 return ERR_PTR(-EINVAL);
608 /* store for use during create */
609 dentry->d_fsdata = &attr;
610 }
611
612 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
613 dentry->d_fsdata = NULL;
614 if (ret)
615 return ERR_PTR(ret);
616
617 filp = dentry_open(dentry, mqueue_mnt, oflag);
618 if (!IS_ERR(filp))
619 dget(dentry);
620
621 return filp;
622 }
623
624 /* Opens existing queue */
625 static struct file *do_open(struct dentry *dentry, int oflag)
626 {
627 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
628 MAY_READ | MAY_WRITE };
629 struct file *filp;
630
631 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
632 return ERR_PTR(-EINVAL);
633
634 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
635 return ERR_PTR(-EACCES);
636
637 filp = dentry_open(dentry, mqueue_mnt, oflag);
638
639 if (!IS_ERR(filp))
640 dget(dentry);
641
642 return filp;
643 }
644
645 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
646 struct mq_attr __user *u_attr)
647 {
648 struct dentry *dentry;
649 struct file *filp;
650 char *name;
651 int fd, error;
652
653 if (IS_ERR(name = getname(u_name)))
654 return PTR_ERR(name);
655
656 fd = get_unused_fd();
657 if (fd < 0)
658 goto out_putname;
659
660 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
661 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
662 if (IS_ERR(dentry)) {
663 error = PTR_ERR(dentry);
664 goto out_err;
665 }
666 mntget(mqueue_mnt);
667
668 if (oflag & O_CREAT) {
669 if (dentry->d_inode) { /* entry already exists */
670 filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
671 do_open(dentry, oflag);
672 } else {
673 filp = do_create(mqueue_mnt->mnt_root, dentry,
674 oflag, mode, u_attr);
675 }
676 } else
677 filp = (dentry->d_inode) ? do_open(dentry, oflag) :
678 ERR_PTR(-ENOENT);
679
680 dput(dentry);
681
682 if (IS_ERR(filp)) {
683 error = PTR_ERR(filp);
684 goto out_putfd;
685 }
686
687 set_close_on_exec(fd, 1);
688 fd_install(fd, filp);
689 goto out_upsem;
690
691 out_putfd:
692 mntput(mqueue_mnt);
693 put_unused_fd(fd);
694 out_err:
695 fd = error;
696 out_upsem:
697 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
698 out_putname:
699 putname(name);
700 return fd;
701 }
702
703 asmlinkage long sys_mq_unlink(const char __user *u_name)
704 {
705 int err;
706 char *name;
707 struct dentry *dentry;
708 struct inode *inode = NULL;
709
710 name = getname(u_name);
711 if (IS_ERR(name))
712 return PTR_ERR(name);
713
714 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
715 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
716 if (IS_ERR(dentry)) {
717 err = PTR_ERR(dentry);
718 goto out_unlock;
719 }
720
721 if (!dentry->d_inode) {
722 err = -ENOENT;
723 goto out_err;
724 }
725
726 inode = dentry->d_inode;
727 if (inode)
728 atomic_inc(&inode->i_count);
729
730 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
731 out_err:
732 dput(dentry);
733
734 out_unlock:
735 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
736 putname(name);
737 if (inode)
738 iput(inode);
739
740 return err;
741 }
742
743 /* Pipelined send and receive functions.
744 *
745 * If a receiver finds no waiting message, then it registers itself in the
746 * list of waiting receivers. A sender checks that list before adding the new
747 * message into the message array. If there is a waiting receiver, then it
748 * bypasses the message array and directly hands the message over to the
749 * receiver.
750 * The receiver accepts the message and returns without grabbing the queue
751 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
752 * are necessary. The same algorithm is used for sysv semaphores, see
753 * ipc/sem.c fore more details.
754 *
755 * The same algorithm is used for senders.
756 */
757
758 /* pipelined_send() - send a message directly to the task waiting in
759 * sys_mq_timedreceive() (without inserting message into a queue).
760 */
761 static inline void pipelined_send(struct mqueue_inode_info *info,
762 struct msg_msg *message,
763 struct ext_wait_queue *receiver)
764 {
765 receiver->msg = message;
766 list_del(&receiver->list);
767 receiver->state = STATE_PENDING;
768 wake_up_process(receiver->task);
769 wmb();
770 receiver->state = STATE_READY;
771 }
772
773 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
774 * gets its message and put to the queue (we have one free place for sure). */
775 static inline void pipelined_receive(struct mqueue_inode_info *info)
776 {
777 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
778
779 if (!sender) {
780 /* for poll */
781 wake_up_interruptible(&info->wait_q);
782 return;
783 }
784 msg_insert(sender->msg, info);
785 list_del(&sender->list);
786 sender->state = STATE_PENDING;
787 wake_up_process(sender->task);
788 wmb();
789 sender->state = STATE_READY;
790 }
791
792 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
793 size_t msg_len, unsigned int msg_prio,
794 const struct timespec __user *u_abs_timeout)
795 {
796 struct file *filp;
797 struct inode *inode;
798 struct ext_wait_queue wait;
799 struct ext_wait_queue *receiver;
800 struct msg_msg *msg_ptr;
801 struct mqueue_inode_info *info;
802 long timeout;
803 int ret;
804
805 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
806 return -EINVAL;
807
808 timeout = prepare_timeout(u_abs_timeout);
809
810 ret = -EBADF;
811 filp = fget(mqdes);
812 if (unlikely(!filp))
813 goto out;
814
815 inode = filp->f_dentry->d_inode;
816 if (unlikely(filp->f_op != &mqueue_file_operations))
817 goto out_fput;
818 info = MQUEUE_I(inode);
819
820 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
821 goto out_fput;
822
823 if (unlikely(msg_len > info->attr.mq_msgsize)) {
824 ret = -EMSGSIZE;
825 goto out_fput;
826 }
827
828 /* First try to allocate memory, before doing anything with
829 * existing queues. */
830 msg_ptr = load_msg(u_msg_ptr, msg_len);
831 if (IS_ERR(msg_ptr)) {
832 ret = PTR_ERR(msg_ptr);
833 goto out_fput;
834 }
835 msg_ptr->m_ts = msg_len;
836 msg_ptr->m_type = msg_prio;
837
838 spin_lock(&info->lock);
839
840 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
841 if (filp->f_flags & O_NONBLOCK) {
842 spin_unlock(&info->lock);
843 ret = -EAGAIN;
844 } else if (unlikely(timeout < 0)) {
845 spin_unlock(&info->lock);
846 ret = timeout;
847 } else {
848 wait.task = current;
849 wait.msg = (void *) msg_ptr;
850 wait.state = STATE_NONE;
851 ret = wq_sleep(info, SEND, timeout, &wait);
852 }
853 if (ret < 0)
854 free_msg(msg_ptr);
855 } else {
856 receiver = wq_get_first_waiter(info, RECV);
857 if (receiver) {
858 pipelined_send(info, msg_ptr, receiver);
859 } else {
860 /* adds message to the queue */
861 msg_insert(msg_ptr, info);
862 __do_notify(info);
863 }
864 inode->i_atime = inode->i_mtime = inode->i_ctime =
865 CURRENT_TIME;
866 spin_unlock(&info->lock);
867 ret = 0;
868 }
869 out_fput:
870 fput(filp);
871 out:
872 return ret;
873 }
874
875 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
876 size_t msg_len, unsigned int __user *u_msg_prio,
877 const struct timespec __user *u_abs_timeout)
878 {
879 long timeout;
880 ssize_t ret;
881 struct msg_msg *msg_ptr;
882 struct file *filp;
883 struct inode *inode;
884 struct mqueue_inode_info *info;
885 struct ext_wait_queue wait;
886
887 timeout = prepare_timeout(u_abs_timeout);
888
889 ret = -EBADF;
890 filp = fget(mqdes);
891 if (unlikely(!filp))
892 goto out;
893
894 inode = filp->f_dentry->d_inode;
895 if (unlikely(filp->f_op != &mqueue_file_operations))
896 goto out_fput;
897 info = MQUEUE_I(inode);
898
899 if (unlikely(!(filp->f_mode & FMODE_READ)))
900 goto out_fput;
901
902 /* checks if buffer is big enough */
903 if (unlikely(msg_len < info->attr.mq_msgsize)) {
904 ret = -EMSGSIZE;
905 goto out_fput;
906 }
907
908 spin_lock(&info->lock);
909 if (info->attr.mq_curmsgs == 0) {
910 if (filp->f_flags & O_NONBLOCK) {
911 spin_unlock(&info->lock);
912 ret = -EAGAIN;
913 msg_ptr = NULL;
914 } else if (unlikely(timeout < 0)) {
915 spin_unlock(&info->lock);
916 ret = timeout;
917 msg_ptr = NULL;
918 } else {
919 wait.task = current;
920 wait.state = STATE_NONE;
921 ret = wq_sleep(info, RECV, timeout, &wait);
922 msg_ptr = wait.msg;
923 }
924 } else {
925 msg_ptr = msg_get(info);
926
927 inode->i_atime = inode->i_mtime = inode->i_ctime =
928 CURRENT_TIME;
929
930 /* There is now free space in queue. */
931 pipelined_receive(info);
932 spin_unlock(&info->lock);
933 ret = 0;
934 }
935 if (ret == 0) {
936 ret = msg_ptr->m_ts;
937
938 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
939 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
940 ret = -EFAULT;
941 }
942 free_msg(msg_ptr);
943 }
944 out_fput:
945 fput(filp);
946 out:
947 return ret;
948 }
949
950 /*
951 * Notes: the case when user wants us to deregister (with NULL as pointer)
952 * and he isn't currently owner of notification, will be silently discarded.
953 * It isn't explicitly defined in the POSIX.
954 */
955 asmlinkage long sys_mq_notify(mqd_t mqdes,
956 const struct sigevent __user *u_notification)
957 {
958 int ret;
959 struct file *filp;
960 struct sock *sock;
961 struct inode *inode;
962 struct sigevent notification;
963 struct mqueue_inode_info *info;
964 struct sk_buff *nc;
965
966 nc = NULL;
967 sock = NULL;
968 if (u_notification != NULL) {
969 if (copy_from_user(&notification, u_notification,
970 sizeof(struct sigevent)))
971 return -EFAULT;
972
973 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
974 notification.sigev_notify != SIGEV_SIGNAL &&
975 notification.sigev_notify != SIGEV_THREAD))
976 return -EINVAL;
977 if (notification.sigev_notify == SIGEV_SIGNAL &&
978 (notification.sigev_signo < 0 ||
979 notification.sigev_signo > _NSIG)) {
980 return -EINVAL;
981 }
982 if (notification.sigev_notify == SIGEV_THREAD) {
983 /* create the notify skb */
984 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
985 ret = -ENOMEM;
986 if (!nc)
987 goto out;
988 ret = -EFAULT;
989 if (copy_from_user(nc->data,
990 notification.sigev_value.sival_ptr,
991 NOTIFY_COOKIE_LEN)) {
992 goto out;
993 }
994
995 /* TODO: add a header? */
996 skb_put(nc, NOTIFY_COOKIE_LEN);
997 /* and attach it to the socket */
998 retry:
999 filp = fget(notification.sigev_signo);
1000 ret = -EBADF;
1001 if (!filp)
1002 goto out;
1003 sock = netlink_getsockbyfilp(filp);
1004 fput(filp);
1005 if (IS_ERR(sock)) {
1006 ret = PTR_ERR(sock);
1007 sock = NULL;
1008 goto out;
1009 }
1010
1011 ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
1012 if (ret == 1)
1013 goto retry;
1014 if (ret) {
1015 sock = NULL;
1016 nc = NULL;
1017 goto out;
1018 }
1019 }
1020 }
1021
1022 ret = -EBADF;
1023 filp = fget(mqdes);
1024 if (!filp)
1025 goto out;
1026
1027 inode = filp->f_dentry->d_inode;
1028 if (unlikely(filp->f_op != &mqueue_file_operations))
1029 goto out_fput;
1030 info = MQUEUE_I(inode);
1031
1032 ret = 0;
1033 spin_lock(&info->lock);
1034 if (u_notification == NULL) {
1035 if (info->notify_owner == current->tgid) {
1036 remove_notification(info);
1037 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1038 }
1039 } else if (info->notify_owner != 0) {
1040 ret = -EBUSY;
1041 } else {
1042 switch (notification.sigev_notify) {
1043 case SIGEV_NONE:
1044 info->notify.sigev_notify = SIGEV_NONE;
1045 break;
1046 case SIGEV_THREAD:
1047 info->notify_sock = sock;
1048 info->notify_cookie = nc;
1049 sock = NULL;
1050 nc = NULL;
1051 info->notify.sigev_notify = SIGEV_THREAD;
1052 break;
1053 case SIGEV_SIGNAL:
1054 info->notify.sigev_signo = notification.sigev_signo;
1055 info->notify.sigev_value = notification.sigev_value;
1056 info->notify.sigev_notify = SIGEV_SIGNAL;
1057 break;
1058 }
1059 info->notify_owner = current->tgid;
1060 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1061 }
1062 spin_unlock(&info->lock);
1063 out_fput:
1064 fput(filp);
1065 out:
1066 if (sock) {
1067 netlink_detachskb(sock, nc);
1068 } else if (nc) {
1069 dev_kfree_skb(nc);
1070 }
1071 return ret;
1072 }
1073
1074 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1075 const struct mq_attr __user *u_mqstat,
1076 struct mq_attr __user *u_omqstat)
1077 {
1078 int ret;
1079 struct mq_attr mqstat, omqstat;
1080 struct file *filp;
1081 struct inode *inode;
1082 struct mqueue_inode_info *info;
1083
1084 if (u_mqstat != NULL) {
1085 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1086 return -EFAULT;
1087 if (mqstat.mq_flags & (~O_NONBLOCK))
1088 return -EINVAL;
1089 }
1090
1091 ret = -EBADF;
1092 filp = fget(mqdes);
1093 if (!filp)
1094 goto out;
1095
1096 inode = filp->f_dentry->d_inode;
1097 if (unlikely(filp->f_op != &mqueue_file_operations))
1098 goto out_fput;
1099 info = MQUEUE_I(inode);
1100
1101 spin_lock(&info->lock);
1102
1103 omqstat = info->attr;
1104 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1105 if (u_mqstat) {
1106 if (mqstat.mq_flags & O_NONBLOCK)
1107 filp->f_flags |= O_NONBLOCK;
1108 else
1109 filp->f_flags &= ~O_NONBLOCK;
1110
1111 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1112 }
1113
1114 spin_unlock(&info->lock);
1115
1116 ret = 0;
1117 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1118 sizeof(struct mq_attr)))
1119 ret = -EFAULT;
1120
1121 out_fput:
1122 fput(filp);
1123 out:
1124 return ret;
1125 }
1126
1127 static struct inode_operations mqueue_dir_inode_operations = {
1128 .lookup = simple_lookup,
1129 .create = mqueue_create,
1130 .unlink = mqueue_unlink,
1131 };
1132
1133 static struct file_operations mqueue_file_operations = {
1134 .flush = mqueue_flush_file,
1135 .poll = mqueue_poll_file,
1136 .read = mqueue_read_file,
1137 };
1138
1139 static struct super_operations mqueue_super_ops = {
1140 .alloc_inode = mqueue_alloc_inode,
1141 .destroy_inode = mqueue_destroy_inode,
1142 .statfs = simple_statfs,
1143 .delete_inode = mqueue_delete_inode,
1144 .drop_inode = generic_delete_inode,
1145 };
1146
1147 static struct file_system_type mqueue_fs_type = {
1148 .name = "mqueue",
1149 .get_sb = mqueue_get_sb,
1150 .kill_sb = kill_litter_super,
1151 };
1152
1153 static int msg_max_limit_min = DFLT_MSGMAX;
1154 static int msg_max_limit_max = HARD_MSGMAX;
1155
1156 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1157 static int msg_maxsize_limit_max = INT_MAX;
1158
1159 static ctl_table mq_sysctls[] = {
1160 {
1161 .ctl_name = CTL_QUEUESMAX,
1162 .procname = "queues_max",
1163 .data = &queues_max,
1164 .maxlen = sizeof(int),
1165 .mode = 0644,
1166 .proc_handler = &proc_dointvec,
1167 },
1168 {
1169 .ctl_name = CTL_MSGMAX,
1170 .procname = "msg_max",
1171 .data = &msg_max,
1172 .maxlen = sizeof(int),
1173 .mode = 0644,
1174 .proc_handler = &proc_dointvec_minmax,
1175 .extra1 = &msg_max_limit_min,
1176 .extra2 = &msg_max_limit_max,
1177 },
1178 {
1179 .ctl_name = CTL_MSGSIZEMAX,
1180 .procname = "msgsize_max",
1181 .data = &msgsize_max,
1182 .maxlen = sizeof(int),
1183 .mode = 0644,
1184 .proc_handler = &proc_dointvec_minmax,
1185 .extra1 = &msg_maxsize_limit_min,
1186 .extra2 = &msg_maxsize_limit_max,
1187 },
1188 { .ctl_name = 0 }
1189 };
1190
1191 static ctl_table mq_sysctl_dir[] = {
1192 {
1193 .ctl_name = FS_MQUEUE,
1194 .procname = "mqueue",
1195 .mode = 0555,
1196 .child = mq_sysctls,
1197 },
1198 { .ctl_name = 0 }
1199 };
1200
1201 static ctl_table mq_sysctl_root[] = {
1202 {
1203 .ctl_name = CTL_FS,
1204 .procname = "fs",
1205 .mode = 0555,
1206 .child = mq_sysctl_dir,
1207 },
1208 { .ctl_name = 0 }
1209 };
1210
1211 static int __init init_mqueue_fs(void)
1212 {
1213 int error;
1214
1215 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1216 sizeof(struct mqueue_inode_info), 0,
1217 SLAB_HWCACHE_ALIGN, init_once, NULL);
1218 if (mqueue_inode_cachep == NULL)
1219 return -ENOMEM;
1220
1221 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1222 if (!mq_sysctl_table) {
1223 error = -ENOMEM;
1224 goto out_cache;
1225 }
1226
1227 error = register_filesystem(&mqueue_fs_type);
1228 if (error)
1229 goto out_sysctl;
1230
1231 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1232 error = PTR_ERR(mqueue_mnt);
1233 goto out_filesystem;
1234 }
1235
1236 /* internal initialization - not common for vfs */
1237 queues_count = 0;
1238 spin_lock_init(&mq_lock);
1239
1240 return 0;
1241
1242 out_filesystem:
1243 unregister_filesystem(&mqueue_fs_type);
1244 out_sysctl:
1245 unregister_sysctl_table(mq_sysctl_table);
1246 out_cache:
1247 if (kmem_cache_destroy(mqueue_inode_cachep)) {
1248 printk(KERN_INFO
1249 "mqueue_inode_cache: not all structures were freed\n");
1250 }
1251 return error;
1252 }
1253
1254 __initcall(init_mqueue_fs);
MOXA 2.6.9 from sdlinux-moxaart.tgz