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[PATCH] Fixed em28xx based system lockup
[linux/fpc-iii.git] / ipc / mqueue.c
blobfd2e26b6f96619fa88d93ed6b4437a257971a52f
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 <net/sock.h>
29 #include "util.h"
30
31 #define MQUEUE_MAGIC 0x19800202
32 #define DIRENT_SIZE 20
33 #define FILENT_SIZE 80
34
35 #define SEND 0
36 #define RECV 1
37
38 #define STATE_NONE 0
39 #define STATE_PENDING 1
40 #define STATE_READY 2
41
42 /* used by sysctl */
43 #define FS_MQUEUE 1
44 #define CTL_QUEUESMAX 2
45 #define CTL_MSGMAX 3
46 #define CTL_MSGSIZEMAX 4
47
48 /* default values */
49 #define DFLT_QUEUESMAX 256 /* max number of message queues */
50 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
51 #define HARD_MSGMAX (131072/sizeof(void*))
52 #define DFLT_MSGSIZEMAX 8192 /* max message size */
53
54 #define NOTIFY_COOKIE_LEN 32
55
56 struct ext_wait_queue { /* queue of sleeping tasks */
57 struct task_struct *task;
58 struct list_head list;
59 struct msg_msg *msg; /* ptr of loaded message */
60 int state; /* one of STATE_* values */
61 };
62
63 struct mqueue_inode_info {
64 spinlock_t lock;
65 struct inode vfs_inode;
66 wait_queue_head_t wait_q;
67
68 struct msg_msg **messages;
69 struct mq_attr attr;
70
71 struct sigevent notify;
72 pid_t notify_owner;
73 struct user_struct *user; /* user who created, for accounting */
74 struct sock *notify_sock;
75 struct sk_buff *notify_cookie;
76
77 /* for tasks waiting for free space and messages, respectively */
78 struct ext_wait_queue e_wait_q[2];
79
80 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
81 };
82
83 static struct inode_operations mqueue_dir_inode_operations;
84 static struct file_operations mqueue_file_operations;
85 static struct super_operations mqueue_super_ops;
86 static void remove_notification(struct mqueue_inode_info *info);
87
88 static spinlock_t mq_lock;
89 static kmem_cache_t *mqueue_inode_cachep;
90 static struct vfsmount *mqueue_mnt;
91
92 static unsigned int queues_count;
93 static unsigned int queues_max = DFLT_QUEUESMAX;
94 static unsigned int msg_max = DFLT_MSGMAX;
95 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
96
97 static struct ctl_table_header * mq_sysctl_table;
98
99 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
100 {
101 return container_of(inode, struct mqueue_inode_info, vfs_inode);
102 }
103
104 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
105 struct mq_attr *attr)
106 {
107 struct inode *inode;
108
109 inode = new_inode(sb);
110 if (inode) {
111 inode->i_mode = mode;
112 inode->i_uid = current->fsuid;
113 inode->i_gid = current->fsgid;
114 inode->i_blksize = PAGE_CACHE_SIZE;
115 inode->i_blocks = 0;
116 inode->i_mtime = inode->i_ctime = inode->i_atime =
117 CURRENT_TIME;
118
119 if (S_ISREG(mode)) {
120 struct mqueue_inode_info *info;
121 struct task_struct *p = current;
122 struct user_struct *u = p->user;
123 unsigned long mq_bytes, mq_msg_tblsz;
124
125 inode->i_fop = &mqueue_file_operations;
126 inode->i_size = FILENT_SIZE;
127 /* mqueue specific info */
128 info = MQUEUE_I(inode);
129 spin_lock_init(&info->lock);
130 init_waitqueue_head(&info->wait_q);
131 INIT_LIST_HEAD(&info->e_wait_q[0].list);
132 INIT_LIST_HEAD(&info->e_wait_q[1].list);
133 info->messages = NULL;
134 info->notify_owner = 0;
135 info->qsize = 0;
136 info->user = NULL; /* set when all is ok */
137 memset(&info->attr, 0, sizeof(info->attr));
138 info->attr.mq_maxmsg = DFLT_MSGMAX;
139 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
140 if (attr) {
141 info->attr.mq_maxmsg = attr->mq_maxmsg;
142 info->attr.mq_msgsize = attr->mq_msgsize;
143 }
144 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
145 mq_bytes = (mq_msg_tblsz +
146 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
147
148 spin_lock(&mq_lock);
149 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
150 u->mq_bytes + mq_bytes >
151 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
152 spin_unlock(&mq_lock);
153 goto out_inode;
154 }
155 u->mq_bytes += mq_bytes;
156 spin_unlock(&mq_lock);
157
158 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
159 if (!info->messages) {
160 spin_lock(&mq_lock);
161 u->mq_bytes -= mq_bytes;
162 spin_unlock(&mq_lock);
163 goto out_inode;
164 }
165 /* all is ok */
166 info->user = get_uid(u);
167 } else if (S_ISDIR(mode)) {
168 inode->i_nlink++;
169 /* Some things misbehave if size == 0 on a directory */
170 inode->i_size = 2 * DIRENT_SIZE;
171 inode->i_op = &mqueue_dir_inode_operations;
172 inode->i_fop = &simple_dir_operations;
173 }
174 }
175 return inode;
176 out_inode:
177 make_bad_inode(inode);
178 iput(inode);
179 return NULL;
180 }
181
182 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
183 {
184 struct inode *inode;
185
186 sb->s_blocksize = PAGE_CACHE_SIZE;
187 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
188 sb->s_magic = MQUEUE_MAGIC;
189 sb->s_op = &mqueue_super_ops;
190
191 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
192 if (!inode)
193 return -ENOMEM;
194
195 sb->s_root = d_alloc_root(inode);
196 if (!sb->s_root) {
197 iput(inode);
198 return -ENOMEM;
199 }
200
201 return 0;
202 }
203
204 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
205 int flags, const char *dev_name,
206 void *data)
207 {
208 return get_sb_single(fs_type, flags, data, mqueue_fill_super);
209 }
210
211 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
212 {
213 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
214
215 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
216 SLAB_CTOR_CONSTRUCTOR)
217 inode_init_once(&p->vfs_inode);
218 }
219
220 static struct inode *mqueue_alloc_inode(struct super_block *sb)
221 {
222 struct mqueue_inode_info *ei;
223
224 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
225 if (!ei)
226 return NULL;
227 return &ei->vfs_inode;
228 }
229
230 static void mqueue_destroy_inode(struct inode *inode)
231 {
232 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
233 }
234
235 static void mqueue_delete_inode(struct inode *inode)
236 {
237 struct mqueue_inode_info *info;
238 struct user_struct *user;
239 unsigned long mq_bytes;
240 int i;
241
242 if (S_ISDIR(inode->i_mode)) {
243 clear_inode(inode);
244 return;
245 }
246 info = MQUEUE_I(inode);
247 spin_lock(&info->lock);
248 for (i = 0; i < info->attr.mq_curmsgs; i++)
249 free_msg(info->messages[i]);
250 kfree(info->messages);
251 spin_unlock(&info->lock);
252
253 clear_inode(inode);
254
255 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
256 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
257 user = info->user;
258 if (user) {
259 spin_lock(&mq_lock);
260 user->mq_bytes -= mq_bytes;
261 queues_count--;
262 spin_unlock(&mq_lock);
263 free_uid(user);
264 }
265 }
266
267 static int mqueue_create(struct inode *dir, struct dentry *dentry,
268 int mode, struct nameidata *nd)
269 {
270 struct inode *inode;
271 struct mq_attr *attr = dentry->d_fsdata;
272 int error;
273
274 spin_lock(&mq_lock);
275 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
276 error = -ENOSPC;
277 goto out_lock;
278 }
279 queues_count++;
280 spin_unlock(&mq_lock);
281
282 inode = mqueue_get_inode(dir->i_sb, mode, attr);
283 if (!inode) {
284 error = -ENOMEM;
285 spin_lock(&mq_lock);
286 queues_count--;
287 goto out_lock;
288 }
289
290 dir->i_size += DIRENT_SIZE;
291 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
292
293 d_instantiate(dentry, inode);
294 dget(dentry);
295 return 0;
296 out_lock:
297 spin_unlock(&mq_lock);
298 return error;
299 }
300
301 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
302 {
303 struct inode *inode = dentry->d_inode;
304
305 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
306 dir->i_size -= DIRENT_SIZE;
307 inode->i_nlink--;
308 dput(dentry);
309 return 0;
310 }
311
312 /*
313 * This is routine for system read from queue file.
314 * To avoid mess with doing here some sort of mq_receive we allow
315 * to read only queue size & notification info (the only values
316 * that are interesting from user point of view and aren't accessible
317 * through std routines)
318 */
319 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
320 size_t count, loff_t * off)
321 {
322 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
323 char buffer[FILENT_SIZE];
324 size_t slen;
325 loff_t o;
326
327 if (!count)
328 return 0;
329
330 spin_lock(&info->lock);
331 snprintf(buffer, sizeof(buffer),
332 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
333 info->qsize,
334 info->notify_owner ? info->notify.sigev_notify : 0,
335 (info->notify_owner &&
336 info->notify.sigev_notify == SIGEV_SIGNAL) ?
337 info->notify.sigev_signo : 0,
338 info->notify_owner);
339 spin_unlock(&info->lock);
340 buffer[sizeof(buffer)-1] = '\0';
341 slen = strlen(buffer)+1;
342
343 o = *off;
344 if (o > slen)
345 return 0;
346
347 if (o + count > slen)
348 count = slen - o;
349
350 if (copy_to_user(u_data, buffer + o, count))
351 return -EFAULT;
352
353 *off = o + count;
354 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
355 return count;
356 }
357
358 static int mqueue_flush_file(struct file *filp)
359 {
360 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
361
362 spin_lock(&info->lock);
363 if (current->tgid == info->notify_owner)
364 remove_notification(info);
365
366 spin_unlock(&info->lock);
367 return 0;
368 }
369
370 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
371 {
372 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
373 int retval = 0;
374
375 poll_wait(filp, &info->wait_q, poll_tab);
376
377 spin_lock(&info->lock);
378 if (info->attr.mq_curmsgs)
379 retval = POLLIN | POLLRDNORM;
380
381 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
382 retval |= POLLOUT | POLLWRNORM;
383 spin_unlock(&info->lock);
384
385 return retval;
386 }
387
388 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
389 static void wq_add(struct mqueue_inode_info *info, int sr,
390 struct ext_wait_queue *ewp)
391 {
392 struct ext_wait_queue *walk;
393
394 ewp->task = current;
395
396 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
397 if (walk->task->static_prio <= current->static_prio) {
398 list_add_tail(&ewp->list, &walk->list);
399 return;
400 }
401 }
402 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
403 }
404
405 /*
406 * Puts current task to sleep. Caller must hold queue lock. After return
407 * lock isn't held.
408 * sr: SEND or RECV
409 */
410 static int wq_sleep(struct mqueue_inode_info *info, int sr,
411 long timeout, struct ext_wait_queue *ewp)
412 {
413 int retval;
414 signed long time;
415
416 wq_add(info, sr, ewp);
417
418 for (;;) {
419 set_current_state(TASK_INTERRUPTIBLE);
420
421 spin_unlock(&info->lock);
422 time = schedule_timeout(timeout);
423
424 while (ewp->state == STATE_PENDING)
425 cpu_relax();
426
427 if (ewp->state == STATE_READY) {
428 retval = 0;
429 goto out;
430 }
431 spin_lock(&info->lock);
432 if (ewp->state == STATE_READY) {
433 retval = 0;
434 goto out_unlock;
435 }
436 if (signal_pending(current)) {
437 retval = -ERESTARTSYS;
438 break;
439 }
440 if (time == 0) {
441 retval = -ETIMEDOUT;
442 break;
443 }
444 }
445 list_del(&ewp->list);
446 out_unlock:
447 spin_unlock(&info->lock);
448 out:
449 return retval;
450 }
451
452 /*
453 * Returns waiting task that should be serviced first or NULL if none exists
454 */
455 static struct ext_wait_queue *wq_get_first_waiter(
456 struct mqueue_inode_info *info, int sr)
457 {
458 struct list_head *ptr;
459
460 ptr = info->e_wait_q[sr].list.prev;
461 if (ptr == &info->e_wait_q[sr].list)
462 return NULL;
463 return list_entry(ptr, struct ext_wait_queue, list);
464 }
465
466 /* Auxiliary functions to manipulate messages' list */
467 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
468 {
469 int k;
470
471 k = info->attr.mq_curmsgs - 1;
472 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
473 info->messages[k + 1] = info->messages[k];
474 k--;
475 }
476 info->attr.mq_curmsgs++;
477 info->qsize += ptr->m_ts;
478 info->messages[k + 1] = ptr;
479 }
480
481 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
482 {
483 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
484 return info->messages[info->attr.mq_curmsgs];
485 }
486
487 static inline void set_cookie(struct sk_buff *skb, char code)
488 {
489 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
490 }
491
492 /*
493 * The next function is only to split too long sys_mq_timedsend
494 */
495 static void __do_notify(struct mqueue_inode_info *info)
496 {
497 /* notification
498 * invoked when there is registered process and there isn't process
499 * waiting synchronously for message AND state of queue changed from
500 * empty to not empty. Here we are sure that no one is waiting
501 * synchronously. */
502 if (info->notify_owner &&
503 info->attr.mq_curmsgs == 1) {
504 struct siginfo sig_i;
505 switch (info->notify.sigev_notify) {
506 case SIGEV_NONE:
507 break;
508 case SIGEV_SIGNAL:
509 /* sends signal */
510
511 sig_i.si_signo = info->notify.sigev_signo;
512 sig_i.si_errno = 0;
513 sig_i.si_code = SI_MESGQ;
514 sig_i.si_value = info->notify.sigev_value;
515 sig_i.si_pid = current->tgid;
516 sig_i.si_uid = current->uid;
517
518 kill_proc_info(info->notify.sigev_signo,
519 &sig_i, info->notify_owner);
520 break;
521 case SIGEV_THREAD:
522 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
523 netlink_sendskb(info->notify_sock,
524 info->notify_cookie, 0);
525 break;
526 }
527 /* after notification unregisters process */
528 info->notify_owner = 0;
529 }
530 wake_up(&info->wait_q);
531 }
532
533 static long prepare_timeout(const struct timespec __user *u_arg)
534 {
535 struct timespec ts, nowts;
536 long timeout;
537
538 if (u_arg) {
539 if (unlikely(copy_from_user(&ts, u_arg,
540 sizeof(struct timespec))))
541 return -EFAULT;
542
543 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
544 || ts.tv_nsec >= NSEC_PER_SEC))
545 return -EINVAL;
546 nowts = CURRENT_TIME;
547 /* first subtract as jiffies can't be too big */
548 ts.tv_sec -= nowts.tv_sec;
549 if (ts.tv_nsec < nowts.tv_nsec) {
550 ts.tv_nsec += NSEC_PER_SEC;
551 ts.tv_sec--;
552 }
553 ts.tv_nsec -= nowts.tv_nsec;
554 if (ts.tv_sec < 0)
555 return 0;
556
557 timeout = timespec_to_jiffies(&ts) + 1;
558 } else
559 return MAX_SCHEDULE_TIMEOUT;
560
561 return timeout;
562 }
563
564 static void remove_notification(struct mqueue_inode_info *info)
565 {
566 if (info->notify_owner != 0 &&
567 info->notify.sigev_notify == SIGEV_THREAD) {
568 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
569 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
570 }
571 info->notify_owner = 0;
572 }
573
574 static int mq_attr_ok(struct mq_attr *attr)
575 {
576 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
577 return 0;
578 if (capable(CAP_SYS_RESOURCE)) {
579 if (attr->mq_maxmsg > HARD_MSGMAX)
580 return 0;
581 } else {
582 if (attr->mq_maxmsg > msg_max ||
583 attr->mq_msgsize > msgsize_max)
584 return 0;
585 }
586 /* check for overflow */
587 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
588 return 0;
589 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
590 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
591 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
592 return 0;
593 return 1;
594 }
595
596 /*
597 * Invoked when creating a new queue via sys_mq_open
598 */
599 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
600 int oflag, mode_t mode, struct mq_attr __user *u_attr)
601 {
602 struct mq_attr attr;
603 int ret;
604
605 if (u_attr) {
606 ret = -EFAULT;
607 if (copy_from_user(&attr, u_attr, sizeof(attr)))
608 goto out;
609 ret = -EINVAL;
610 if (!mq_attr_ok(&attr))
611 goto out;
612 /* store for use during create */
613 dentry->d_fsdata = &attr;
614 }
615
616 mode &= ~current->fs->umask;
617 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
618 dentry->d_fsdata = NULL;
619 if (ret)
620 goto out;
621
622 return dentry_open(dentry, mqueue_mnt, oflag);
623
624 out:
625 dput(dentry);
626 mntput(mqueue_mnt);
627 return ERR_PTR(ret);
628 }
629
630 /* Opens existing queue */
631 static struct file *do_open(struct dentry *dentry, int oflag)
632 {
633 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
634 MAY_READ | MAY_WRITE };
635
636 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
637 dput(dentry);
638 mntput(mqueue_mnt);
639 return ERR_PTR(-EINVAL);
640 }
641
642 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
643 dput(dentry);
644 mntput(mqueue_mnt);
645 return ERR_PTR(-EACCES);
646 }
647
648 return dentry_open(dentry, mqueue_mnt, oflag);
649 }
650
651 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
652 struct mq_attr __user *u_attr)
653 {
654 struct dentry *dentry;
655 struct file *filp;
656 char *name;
657 int fd, error;
658
659 if (IS_ERR(name = getname(u_name)))
660 return PTR_ERR(name);
661
662 fd = get_unused_fd();
663 if (fd < 0)
664 goto out_putname;
665
666 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
667 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
668 if (IS_ERR(dentry)) {
669 error = PTR_ERR(dentry);
670 goto out_err;
671 }
672 mntget(mqueue_mnt);
673
674 if (oflag & O_CREAT) {
675 if (dentry->d_inode) { /* entry already exists */
676 error = -EEXIST;
677 if (oflag & O_EXCL)
678 goto out;
679 filp = do_open(dentry, oflag);
680 } else {
681 filp = do_create(mqueue_mnt->mnt_root, dentry,
682 oflag, mode, u_attr);
683 }
684 } else {
685 error = -ENOENT;
686 if (!dentry->d_inode)
687 goto out;
688 filp = do_open(dentry, oflag);
689 }
690
691 if (IS_ERR(filp)) {
692 error = PTR_ERR(filp);
693 goto out_putfd;
694 }
695
696 set_close_on_exec(fd, 1);
697 fd_install(fd, filp);
698 goto out_upsem;
699
700 out:
701 dput(dentry);
702 mntput(mqueue_mnt);
703 out_putfd:
704 put_unused_fd(fd);
705 out_err:
706 fd = error;
707 out_upsem:
708 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
709 out_putname:
710 putname(name);
711 return fd;
712 }
713
714 asmlinkage long sys_mq_unlink(const char __user *u_name)
715 {
716 int err;
717 char *name;
718 struct dentry *dentry;
719 struct inode *inode = NULL;
720
721 name = getname(u_name);
722 if (IS_ERR(name))
723 return PTR_ERR(name);
724
725 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
726 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
727 if (IS_ERR(dentry)) {
728 err = PTR_ERR(dentry);
729 goto out_unlock;
730 }
731
732 if (!dentry->d_inode) {
733 err = -ENOENT;
734 goto out_err;
735 }
736
737 inode = dentry->d_inode;
738 if (inode)
739 atomic_inc(&inode->i_count);
740
741 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
742 out_err:
743 dput(dentry);
744
745 out_unlock:
746 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
747 putname(name);
748 if (inode)
749 iput(inode);
750
751 return err;
752 }
753
754 /* Pipelined send and receive functions.
755 *
756 * If a receiver finds no waiting message, then it registers itself in the
757 * list of waiting receivers. A sender checks that list before adding the new
758 * message into the message array. If there is a waiting receiver, then it
759 * bypasses the message array and directly hands the message over to the
760 * receiver.
761 * The receiver accepts the message and returns without grabbing the queue
762 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
763 * are necessary. The same algorithm is used for sysv semaphores, see
764 * ipc/sem.c fore more details.
765 *
766 * The same algorithm is used for senders.
767 */
768
769 /* pipelined_send() - send a message directly to the task waiting in
770 * sys_mq_timedreceive() (without inserting message into a queue).
771 */
772 static inline void pipelined_send(struct mqueue_inode_info *info,
773 struct msg_msg *message,
774 struct ext_wait_queue *receiver)
775 {
776 receiver->msg = message;
777 list_del(&receiver->list);
778 receiver->state = STATE_PENDING;
779 wake_up_process(receiver->task);
780 smp_wmb();
781 receiver->state = STATE_READY;
782 }
783
784 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
785 * gets its message and put to the queue (we have one free place for sure). */
786 static inline void pipelined_receive(struct mqueue_inode_info *info)
787 {
788 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
789
790 if (!sender) {
791 /* for poll */
792 wake_up_interruptible(&info->wait_q);
793 return;
794 }
795 msg_insert(sender->msg, info);
796 list_del(&sender->list);
797 sender->state = STATE_PENDING;
798 wake_up_process(sender->task);
799 smp_wmb();
800 sender->state = STATE_READY;
801 }
802
803 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
804 size_t msg_len, unsigned int msg_prio,
805 const struct timespec __user *u_abs_timeout)
806 {
807 struct file *filp;
808 struct inode *inode;
809 struct ext_wait_queue wait;
810 struct ext_wait_queue *receiver;
811 struct msg_msg *msg_ptr;
812 struct mqueue_inode_info *info;
813 long timeout;
814 int ret;
815
816 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
817 return -EINVAL;
818
819 timeout = prepare_timeout(u_abs_timeout);
820
821 ret = -EBADF;
822 filp = fget(mqdes);
823 if (unlikely(!filp))
824 goto out;
825
826 inode = filp->f_dentry->d_inode;
827 if (unlikely(filp->f_op != &mqueue_file_operations))
828 goto out_fput;
829 info = MQUEUE_I(inode);
830
831 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
832 goto out_fput;
833
834 if (unlikely(msg_len > info->attr.mq_msgsize)) {
835 ret = -EMSGSIZE;
836 goto out_fput;
837 }
838
839 /* First try to allocate memory, before doing anything with
840 * existing queues. */
841 msg_ptr = load_msg(u_msg_ptr, msg_len);
842 if (IS_ERR(msg_ptr)) {
843 ret = PTR_ERR(msg_ptr);
844 goto out_fput;
845 }
846 msg_ptr->m_ts = msg_len;
847 msg_ptr->m_type = msg_prio;
848
849 spin_lock(&info->lock);
850
851 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
852 if (filp->f_flags & O_NONBLOCK) {
853 spin_unlock(&info->lock);
854 ret = -EAGAIN;
855 } else if (unlikely(timeout < 0)) {
856 spin_unlock(&info->lock);
857 ret = timeout;
858 } else {
859 wait.task = current;
860 wait.msg = (void *) msg_ptr;
861 wait.state = STATE_NONE;
862 ret = wq_sleep(info, SEND, timeout, &wait);
863 }
864 if (ret < 0)
865 free_msg(msg_ptr);
866 } else {
867 receiver = wq_get_first_waiter(info, RECV);
868 if (receiver) {
869 pipelined_send(info, msg_ptr, receiver);
870 } else {
871 /* adds message to the queue */
872 msg_insert(msg_ptr, info);
873 __do_notify(info);
874 }
875 inode->i_atime = inode->i_mtime = inode->i_ctime =
876 CURRENT_TIME;
877 spin_unlock(&info->lock);
878 ret = 0;
879 }
880 out_fput:
881 fput(filp);
882 out:
883 return ret;
884 }
885
886 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
887 size_t msg_len, unsigned int __user *u_msg_prio,
888 const struct timespec __user *u_abs_timeout)
889 {
890 long timeout;
891 ssize_t ret;
892 struct msg_msg *msg_ptr;
893 struct file *filp;
894 struct inode *inode;
895 struct mqueue_inode_info *info;
896 struct ext_wait_queue wait;
897
898 timeout = prepare_timeout(u_abs_timeout);
899
900 ret = -EBADF;
901 filp = fget(mqdes);
902 if (unlikely(!filp))
903 goto out;
904
905 inode = filp->f_dentry->d_inode;
906 if (unlikely(filp->f_op != &mqueue_file_operations))
907 goto out_fput;
908 info = MQUEUE_I(inode);
909
910 if (unlikely(!(filp->f_mode & FMODE_READ)))
911 goto out_fput;
912
913 /* checks if buffer is big enough */
914 if (unlikely(msg_len < info->attr.mq_msgsize)) {
915 ret = -EMSGSIZE;
916 goto out_fput;
917 }
918
919 spin_lock(&info->lock);
920 if (info->attr.mq_curmsgs == 0) {
921 if (filp->f_flags & O_NONBLOCK) {
922 spin_unlock(&info->lock);
923 ret = -EAGAIN;
924 msg_ptr = NULL;
925 } else if (unlikely(timeout < 0)) {
926 spin_unlock(&info->lock);
927 ret = timeout;
928 msg_ptr = NULL;
929 } else {
930 wait.task = current;
931 wait.state = STATE_NONE;
932 ret = wq_sleep(info, RECV, timeout, &wait);
933 msg_ptr = wait.msg;
934 }
935 } else {
936 msg_ptr = msg_get(info);
937
938 inode->i_atime = inode->i_mtime = inode->i_ctime =
939 CURRENT_TIME;
940
941 /* There is now free space in queue. */
942 pipelined_receive(info);
943 spin_unlock(&info->lock);
944 ret = 0;
945 }
946 if (ret == 0) {
947 ret = msg_ptr->m_ts;
948
949 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
950 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
951 ret = -EFAULT;
952 }
953 free_msg(msg_ptr);
954 }
955 out_fput:
956 fput(filp);
957 out:
958 return ret;
959 }
960
961 /*
962 * Notes: the case when user wants us to deregister (with NULL as pointer)
963 * and he isn't currently owner of notification, will be silently discarded.
964 * It isn't explicitly defined in the POSIX.
965 */
966 asmlinkage long sys_mq_notify(mqd_t mqdes,
967 const struct sigevent __user *u_notification)
968 {
969 int ret;
970 struct file *filp;
971 struct sock *sock;
972 struct inode *inode;
973 struct sigevent notification;
974 struct mqueue_inode_info *info;
975 struct sk_buff *nc;
976
977 nc = NULL;
978 sock = NULL;
979 if (u_notification != NULL) {
980 if (copy_from_user(&notification, u_notification,
981 sizeof(struct sigevent)))
982 return -EFAULT;
983
984 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
985 notification.sigev_notify != SIGEV_SIGNAL &&
986 notification.sigev_notify != SIGEV_THREAD))
987 return -EINVAL;
988 if (notification.sigev_notify == SIGEV_SIGNAL &&
989 !valid_signal(notification.sigev_signo)) {
990 return -EINVAL;
991 }
992 if (notification.sigev_notify == SIGEV_THREAD) {
993 /* create the notify skb */
994 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
995 ret = -ENOMEM;
996 if (!nc)
997 goto out;
998 ret = -EFAULT;
999 if (copy_from_user(nc->data,
1000 notification.sigev_value.sival_ptr,
1001 NOTIFY_COOKIE_LEN)) {
1002 goto out;
1003 }
1004
1005 /* TODO: add a header? */
1006 skb_put(nc, NOTIFY_COOKIE_LEN);
1007 /* and attach it to the socket */
1008 retry:
1009 filp = fget(notification.sigev_signo);
1010 ret = -EBADF;
1011 if (!filp)
1012 goto out;
1013 sock = netlink_getsockbyfilp(filp);
1014 fput(filp);
1015 if (IS_ERR(sock)) {
1016 ret = PTR_ERR(sock);
1017 sock = NULL;
1018 goto out;
1019 }
1020
1021 ret = netlink_attachskb(sock, nc, 0,
1022 MAX_SCHEDULE_TIMEOUT, NULL);
1023 if (ret == 1)
1024 goto retry;
1025 if (ret) {
1026 sock = NULL;
1027 nc = NULL;
1028 goto out;
1029 }
1030 }
1031 }
1032
1033 ret = -EBADF;
1034 filp = fget(mqdes);
1035 if (!filp)
1036 goto out;
1037
1038 inode = filp->f_dentry->d_inode;
1039 if (unlikely(filp->f_op != &mqueue_file_operations))
1040 goto out_fput;
1041 info = MQUEUE_I(inode);
1042
1043 ret = 0;
1044 spin_lock(&info->lock);
1045 if (u_notification == NULL) {
1046 if (info->notify_owner == current->tgid) {
1047 remove_notification(info);
1048 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1049 }
1050 } else if (info->notify_owner != 0) {
1051 ret = -EBUSY;
1052 } else {
1053 switch (notification.sigev_notify) {
1054 case SIGEV_NONE:
1055 info->notify.sigev_notify = SIGEV_NONE;
1056 break;
1057 case SIGEV_THREAD:
1058 info->notify_sock = sock;
1059 info->notify_cookie = nc;
1060 sock = NULL;
1061 nc = NULL;
1062 info->notify.sigev_notify = SIGEV_THREAD;
1063 break;
1064 case SIGEV_SIGNAL:
1065 info->notify.sigev_signo = notification.sigev_signo;
1066 info->notify.sigev_value = notification.sigev_value;
1067 info->notify.sigev_notify = SIGEV_SIGNAL;
1068 break;
1069 }
1070 info->notify_owner = current->tgid;
1071 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1072 }
1073 spin_unlock(&info->lock);
1074 out_fput:
1075 fput(filp);
1076 out:
1077 if (sock) {
1078 netlink_detachskb(sock, nc);
1079 } else if (nc) {
1080 dev_kfree_skb(nc);
1081 }
1082 return ret;
1083 }
1084
1085 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1086 const struct mq_attr __user *u_mqstat,
1087 struct mq_attr __user *u_omqstat)
1088 {
1089 int ret;
1090 struct mq_attr mqstat, omqstat;
1091 struct file *filp;
1092 struct inode *inode;
1093 struct mqueue_inode_info *info;
1094
1095 if (u_mqstat != NULL) {
1096 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1097 return -EFAULT;
1098 if (mqstat.mq_flags & (~O_NONBLOCK))
1099 return -EINVAL;
1100 }
1101
1102 ret = -EBADF;
1103 filp = fget(mqdes);
1104 if (!filp)
1105 goto out;
1106
1107 inode = filp->f_dentry->d_inode;
1108 if (unlikely(filp->f_op != &mqueue_file_operations))
1109 goto out_fput;
1110 info = MQUEUE_I(inode);
1111
1112 spin_lock(&info->lock);
1113
1114 omqstat = info->attr;
1115 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1116 if (u_mqstat) {
1117 if (mqstat.mq_flags & O_NONBLOCK)
1118 filp->f_flags |= O_NONBLOCK;
1119 else
1120 filp->f_flags &= ~O_NONBLOCK;
1121
1122 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1123 }
1124
1125 spin_unlock(&info->lock);
1126
1127 ret = 0;
1128 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1129 sizeof(struct mq_attr)))
1130 ret = -EFAULT;
1131
1132 out_fput:
1133 fput(filp);
1134 out:
1135 return ret;
1136 }
1137
1138 static struct inode_operations mqueue_dir_inode_operations = {
1139 .lookup = simple_lookup,
1140 .create = mqueue_create,
1141 .unlink = mqueue_unlink,
1142 };
1143
1144 static struct file_operations mqueue_file_operations = {
1145 .flush = mqueue_flush_file,
1146 .poll = mqueue_poll_file,
1147 .read = mqueue_read_file,
1148 };
1149
1150 static struct super_operations mqueue_super_ops = {
1151 .alloc_inode = mqueue_alloc_inode,
1152 .destroy_inode = mqueue_destroy_inode,
1153 .statfs = simple_statfs,
1154 .delete_inode = mqueue_delete_inode,
1155 .drop_inode = generic_delete_inode,
1156 };
1157
1158 static struct file_system_type mqueue_fs_type = {
1159 .name = "mqueue",
1160 .get_sb = mqueue_get_sb,
1161 .kill_sb = kill_litter_super,
1162 };
1163
1164 static int msg_max_limit_min = DFLT_MSGMAX;
1165 static int msg_max_limit_max = HARD_MSGMAX;
1166
1167 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1168 static int msg_maxsize_limit_max = INT_MAX;
1169
1170 static ctl_table mq_sysctls[] = {
1171 {
1172 .ctl_name = CTL_QUEUESMAX,
1173 .procname = "queues_max",
1174 .data = &queues_max,
1175 .maxlen = sizeof(int),
1176 .mode = 0644,
1177 .proc_handler = &proc_dointvec,
1178 },
1179 {
1180 .ctl_name = CTL_MSGMAX,
1181 .procname = "msg_max",
1182 .data = &msg_max,
1183 .maxlen = sizeof(int),
1184 .mode = 0644,
1185 .proc_handler = &proc_dointvec_minmax,
1186 .extra1 = &msg_max_limit_min,
1187 .extra2 = &msg_max_limit_max,
1188 },
1189 {
1190 .ctl_name = CTL_MSGSIZEMAX,
1191 .procname = "msgsize_max",
1192 .data = &msgsize_max,
1193 .maxlen = sizeof(int),
1194 .mode = 0644,
1195 .proc_handler = &proc_dointvec_minmax,
1196 .extra1 = &msg_maxsize_limit_min,
1197 .extra2 = &msg_maxsize_limit_max,
1198 },
1199 { .ctl_name = 0 }
1200 };
1201
1202 static ctl_table mq_sysctl_dir[] = {
1203 {
1204 .ctl_name = FS_MQUEUE,
1205 .procname = "mqueue",
1206 .mode = 0555,
1207 .child = mq_sysctls,
1208 },
1209 { .ctl_name = 0 }
1210 };
1211
1212 static ctl_table mq_sysctl_root[] = {
1213 {
1214 .ctl_name = CTL_FS,
1215 .procname = "fs",
1216 .mode = 0555,
1217 .child = mq_sysctl_dir,
1218 },
1219 { .ctl_name = 0 }
1220 };
1221
1222 static int __init init_mqueue_fs(void)
1223 {
1224 int error;
1225
1226 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1227 sizeof(struct mqueue_inode_info), 0,
1228 SLAB_HWCACHE_ALIGN, init_once, NULL);
1229 if (mqueue_inode_cachep == NULL)
1230 return -ENOMEM;
1231
1232 /* ignore failues - they are not fatal */
1233 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1234
1235 error = register_filesystem(&mqueue_fs_type);
1236 if (error)
1237 goto out_sysctl;
1238
1239 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1240 error = PTR_ERR(mqueue_mnt);
1241 goto out_filesystem;
1242 }
1243
1244 /* internal initialization - not common for vfs */
1245 queues_count = 0;
1246 spin_lock_init(&mq_lock);
1247
1248 return 0;
1249
1250 out_filesystem:
1251 unregister_filesystem(&mqueue_fs_type);
1252 out_sysctl:
1253 if (mq_sysctl_table)
1254 unregister_sysctl_table(mq_sysctl_table);
1255 if (kmem_cache_destroy(mqueue_inode_cachep)) {
1256 printk(KERN_INFO
1257 "mqueue_inode_cache: not all structures were freed\n");
1258 }
1259 return error;
1260 }
1261
1262 __initcall(init_mqueue_fs);
Linux with added FPC-III support