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[ATM]: atm_pcr_goal() doesn't modify its argument's contents -- mark it as const
[linux/fpc-iii.git] / ipc / mqueue.c
blobc8943b53d8e6c3620f5dd3237c34af6462e6740d
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/init.h>
15 #include <linux/pagemap.h>
16 #include <linux/file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include <linux/sysctl.h>
20 #include <linux/poll.h>
21 #include <linux/mqueue.h>
22 #include <linux/msg.h>
23 #include <linux/skbuff.h>
24 #include <linux/netlink.h>
25 #include <linux/syscalls.h>
26 #include <linux/signal.h>
27 #include <net/sock.h>
28 #include "util.h"
29
30 #define MQUEUE_MAGIC 0x19800202
31 #define DIRENT_SIZE 20
32 #define FILENT_SIZE 80
33
34 #define SEND 0
35 #define RECV 1
36
37 #define STATE_NONE 0
38 #define STATE_PENDING 1
39 #define STATE_READY 2
40
41 /* used by sysctl */
42 #define FS_MQUEUE 1
43 #define CTL_QUEUESMAX 2
44 #define CTL_MSGMAX 3
45 #define CTL_MSGSIZEMAX 4
46
47 /* default values */
48 #define DFLT_QUEUESMAX 256 /* max number of message queues */
49 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
50 #define HARD_MSGMAX (131072/sizeof(void*))
51 #define DFLT_MSGSIZEMAX 8192 /* max message size */
52
53 #define NOTIFY_COOKIE_LEN 32
54
55 struct ext_wait_queue { /* queue of sleeping tasks */
56 struct task_struct *task;
57 struct list_head list;
58 struct msg_msg *msg; /* ptr of loaded message */
59 int state; /* one of STATE_* values */
60 };
61
62 struct mqueue_inode_info {
63 spinlock_t lock;
64 struct inode vfs_inode;
65 wait_queue_head_t wait_q;
66
67 struct msg_msg **messages;
68 struct mq_attr attr;
69
70 struct sigevent notify;
71 pid_t notify_owner;
72 struct user_struct *user; /* user who created, for accounting */
73 struct sock *notify_sock;
74 struct sk_buff *notify_cookie;
75
76 /* for tasks waiting for free space and messages, respectively */
77 struct ext_wait_queue e_wait_q[2];
78
79 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
80 };
81
82 static struct inode_operations mqueue_dir_inode_operations;
83 static struct file_operations mqueue_file_operations;
84 static struct super_operations mqueue_super_ops;
85 static void remove_notification(struct mqueue_inode_info *info);
86
87 static spinlock_t mq_lock;
88 static kmem_cache_t *mqueue_inode_cachep;
89 static struct vfsmount *mqueue_mnt;
90
91 static unsigned int queues_count;
92 static unsigned int queues_max = DFLT_QUEUESMAX;
93 static unsigned int msg_max = DFLT_MSGMAX;
94 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
95
96 static struct ctl_table_header * mq_sysctl_table;
97
98 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
99 {
100 return container_of(inode, struct mqueue_inode_info, vfs_inode);
101 }
102
103 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
104 struct mq_attr *attr)
105 {
106 struct inode *inode;
107
108 inode = new_inode(sb);
109 if (inode) {
110 inode->i_mode = mode;
111 inode->i_uid = current->fsuid;
112 inode->i_gid = current->fsgid;
113 inode->i_blksize = PAGE_CACHE_SIZE;
114 inode->i_blocks = 0;
115 inode->i_mtime = inode->i_ctime = inode->i_atime =
116 CURRENT_TIME;
117
118 if (S_ISREG(mode)) {
119 struct mqueue_inode_info *info;
120 struct task_struct *p = current;
121 struct user_struct *u = p->user;
122 unsigned long mq_bytes, mq_msg_tblsz;
123
124 inode->i_fop = &mqueue_file_operations;
125 inode->i_size = FILENT_SIZE;
126 /* mqueue specific info */
127 info = MQUEUE_I(inode);
128 spin_lock_init(&info->lock);
129 init_waitqueue_head(&info->wait_q);
130 INIT_LIST_HEAD(&info->e_wait_q[0].list);
131 INIT_LIST_HEAD(&info->e_wait_q[1].list);
132 info->messages = NULL;
133 info->notify_owner = 0;
134 info->qsize = 0;
135 info->user = NULL; /* set when all is ok */
136 memset(&info->attr, 0, sizeof(info->attr));
137 info->attr.mq_maxmsg = DFLT_MSGMAX;
138 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
139 if (attr) {
140 info->attr.mq_maxmsg = attr->mq_maxmsg;
141 info->attr.mq_msgsize = attr->mq_msgsize;
142 }
143 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
144 mq_bytes = (mq_msg_tblsz +
145 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
146
147 spin_lock(&mq_lock);
148 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
149 u->mq_bytes + mq_bytes >
150 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
151 spin_unlock(&mq_lock);
152 goto out_inode;
153 }
154 u->mq_bytes += mq_bytes;
155 spin_unlock(&mq_lock);
156
157 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
158 if (!info->messages) {
159 spin_lock(&mq_lock);
160 u->mq_bytes -= mq_bytes;
161 spin_unlock(&mq_lock);
162 goto out_inode;
163 }
164 /* all is ok */
165 info->user = get_uid(u);
166 } else if (S_ISDIR(mode)) {
167 inode->i_nlink++;
168 /* Some things misbehave if size == 0 on a directory */
169 inode->i_size = 2 * DIRENT_SIZE;
170 inode->i_op = &mqueue_dir_inode_operations;
171 inode->i_fop = &simple_dir_operations;
172 }
173 }
174 return inode;
175 out_inode:
176 make_bad_inode(inode);
177 iput(inode);
178 return NULL;
179 }
180
181 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
182 {
183 struct inode *inode;
184
185 sb->s_blocksize = PAGE_CACHE_SIZE;
186 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
187 sb->s_magic = MQUEUE_MAGIC;
188 sb->s_op = &mqueue_super_ops;
189
190 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
191 if (!inode)
192 return -ENOMEM;
193
194 sb->s_root = d_alloc_root(inode);
195 if (!sb->s_root) {
196 iput(inode);
197 return -ENOMEM;
198 }
199
200 return 0;
201 }
202
203 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
204 int flags, const char *dev_name,
205 void *data)
206 {
207 return get_sb_single(fs_type, flags, data, mqueue_fill_super);
208 }
209
210 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
211 {
212 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
213
214 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
215 SLAB_CTOR_CONSTRUCTOR)
216 inode_init_once(&p->vfs_inode);
217 }
218
219 static struct inode *mqueue_alloc_inode(struct super_block *sb)
220 {
221 struct mqueue_inode_info *ei;
222
223 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
224 if (!ei)
225 return NULL;
226 return &ei->vfs_inode;
227 }
228
229 static void mqueue_destroy_inode(struct inode *inode)
230 {
231 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
232 }
233
234 static void mqueue_delete_inode(struct inode *inode)
235 {
236 struct mqueue_inode_info *info;
237 struct user_struct *user;
238 unsigned long mq_bytes;
239 int i;
240
241 if (S_ISDIR(inode->i_mode)) {
242 clear_inode(inode);
243 return;
244 }
245 info = MQUEUE_I(inode);
246 spin_lock(&info->lock);
247 for (i = 0; i < info->attr.mq_curmsgs; i++)
248 free_msg(info->messages[i]);
249 kfree(info->messages);
250 spin_unlock(&info->lock);
251
252 clear_inode(inode);
253
254 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
255 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
256 user = info->user;
257 if (user) {
258 spin_lock(&mq_lock);
259 user->mq_bytes -= mq_bytes;
260 queues_count--;
261 spin_unlock(&mq_lock);
262 free_uid(user);
263 }
264 }
265
266 static int mqueue_create(struct inode *dir, struct dentry *dentry,
267 int mode, struct nameidata *nd)
268 {
269 struct inode *inode;
270 struct mq_attr *attr = dentry->d_fsdata;
271 int error;
272
273 spin_lock(&mq_lock);
274 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
275 error = -ENOSPC;
276 goto out_lock;
277 }
278 queues_count++;
279 spin_unlock(&mq_lock);
280
281 inode = mqueue_get_inode(dir->i_sb, mode, attr);
282 if (!inode) {
283 error = -ENOMEM;
284 spin_lock(&mq_lock);
285 queues_count--;
286 goto out_lock;
287 }
288
289 dir->i_size += DIRENT_SIZE;
290 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
291
292 d_instantiate(dentry, inode);
293 dget(dentry);
294 return 0;
295 out_lock:
296 spin_unlock(&mq_lock);
297 return error;
298 }
299
300 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
301 {
302 struct inode *inode = dentry->d_inode;
303
304 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
305 dir->i_size -= DIRENT_SIZE;
306 inode->i_nlink--;
307 dput(dentry);
308 return 0;
309 }
310
311 /*
312 * This is routine for system read from queue file.
313 * To avoid mess with doing here some sort of mq_receive we allow
314 * to read only queue size & notification info (the only values
315 * that are interesting from user point of view and aren't accessible
316 * through std routines)
317 */
318 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
319 size_t count, loff_t * off)
320 {
321 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
322 char buffer[FILENT_SIZE];
323 size_t slen;
324 loff_t o;
325
326 if (!count)
327 return 0;
328
329 spin_lock(&info->lock);
330 snprintf(buffer, sizeof(buffer),
331 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
332 info->qsize,
333 info->notify_owner ? info->notify.sigev_notify : 0,
334 (info->notify_owner &&
335 info->notify.sigev_notify == SIGEV_SIGNAL) ?
336 info->notify.sigev_signo : 0,
337 info->notify_owner);
338 spin_unlock(&info->lock);
339 buffer[sizeof(buffer)-1] = '\0';
340 slen = strlen(buffer)+1;
341
342 o = *off;
343 if (o > slen)
344 return 0;
345
346 if (o + count > slen)
347 count = slen - o;
348
349 if (copy_to_user(u_data, buffer + o, count))
350 return -EFAULT;
351
352 *off = o + count;
353 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
354 return count;
355 }
356
357 static int mqueue_flush_file(struct file *filp)
358 {
359 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
360
361 spin_lock(&info->lock);
362 if (current->tgid == info->notify_owner)
363 remove_notification(info);
364
365 spin_unlock(&info->lock);
366 return 0;
367 }
368
369 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
370 {
371 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
372 int retval = 0;
373
374 poll_wait(filp, &info->wait_q, poll_tab);
375
376 spin_lock(&info->lock);
377 if (info->attr.mq_curmsgs)
378 retval = POLLIN | POLLRDNORM;
379
380 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
381 retval |= POLLOUT | POLLWRNORM;
382 spin_unlock(&info->lock);
383
384 return retval;
385 }
386
387 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
388 static void wq_add(struct mqueue_inode_info *info, int sr,
389 struct ext_wait_queue *ewp)
390 {
391 struct ext_wait_queue *walk;
392
393 ewp->task = current;
394
395 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
396 if (walk->task->static_prio <= current->static_prio) {
397 list_add_tail(&ewp->list, &walk->list);
398 return;
399 }
400 }
401 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
402 }
403
404 /*
405 * Puts current task to sleep. Caller must hold queue lock. After return
406 * lock isn't held.
407 * sr: SEND or RECV
408 */
409 static int wq_sleep(struct mqueue_inode_info *info, int sr,
410 long timeout, struct ext_wait_queue *ewp)
411 {
412 int retval;
413 signed long time;
414
415 wq_add(info, sr, ewp);
416
417 for (;;) {
418 set_current_state(TASK_INTERRUPTIBLE);
419
420 spin_unlock(&info->lock);
421 time = schedule_timeout(timeout);
422
423 while (ewp->state == STATE_PENDING)
424 cpu_relax();
425
426 if (ewp->state == STATE_READY) {
427 retval = 0;
428 goto out;
429 }
430 spin_lock(&info->lock);
431 if (ewp->state == STATE_READY) {
432 retval = 0;
433 goto out_unlock;
434 }
435 if (signal_pending(current)) {
436 retval = -ERESTARTSYS;
437 break;
438 }
439 if (time == 0) {
440 retval = -ETIMEDOUT;
441 break;
442 }
443 }
444 list_del(&ewp->list);
445 out_unlock:
446 spin_unlock(&info->lock);
447 out:
448 return retval;
449 }
450
451 /*
452 * Returns waiting task that should be serviced first or NULL if none exists
453 */
454 static struct ext_wait_queue *wq_get_first_waiter(
455 struct mqueue_inode_info *info, int sr)
456 {
457 struct list_head *ptr;
458
459 ptr = info->e_wait_q[sr].list.prev;
460 if (ptr == &info->e_wait_q[sr].list)
461 return NULL;
462 return list_entry(ptr, struct ext_wait_queue, list);
463 }
464
465 /* Auxiliary functions to manipulate messages' list */
466 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
467 {
468 int k;
469
470 k = info->attr.mq_curmsgs - 1;
471 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
472 info->messages[k + 1] = info->messages[k];
473 k--;
474 }
475 info->attr.mq_curmsgs++;
476 info->qsize += ptr->m_ts;
477 info->messages[k + 1] = ptr;
478 }
479
480 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
481 {
482 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
483 return info->messages[info->attr.mq_curmsgs];
484 }
485
486 static inline void set_cookie(struct sk_buff *skb, char code)
487 {
488 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
489 }
490
491 /*
492 * The next function is only to split too long sys_mq_timedsend
493 */
494 static void __do_notify(struct mqueue_inode_info *info)
495 {
496 /* notification
497 * invoked when there is registered process and there isn't process
498 * waiting synchronously for message AND state of queue changed from
499 * empty to not empty. Here we are sure that no one is waiting
500 * synchronously. */
501 if (info->notify_owner &&
502 info->attr.mq_curmsgs == 1) {
503 struct siginfo sig_i;
504 switch (info->notify.sigev_notify) {
505 case SIGEV_NONE:
506 break;
507 case SIGEV_SIGNAL:
508 /* sends signal */
509
510 sig_i.si_signo = info->notify.sigev_signo;
511 sig_i.si_errno = 0;
512 sig_i.si_code = SI_MESGQ;
513 sig_i.si_value = info->notify.sigev_value;
514 sig_i.si_pid = current->tgid;
515 sig_i.si_uid = current->uid;
516
517 kill_proc_info(info->notify.sigev_signo,
518 &sig_i, info->notify_owner);
519 break;
520 case SIGEV_THREAD:
521 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
522 netlink_sendskb(info->notify_sock,
523 info->notify_cookie, 0);
524 break;
525 }
526 /* after notification unregisters process */
527 info->notify_owner = 0;
528 }
529 wake_up(&info->wait_q);
530 }
531
532 static long prepare_timeout(const struct timespec __user *u_arg)
533 {
534 struct timespec ts, nowts;
535 long timeout;
536
537 if (u_arg) {
538 if (unlikely(copy_from_user(&ts, u_arg,
539 sizeof(struct timespec))))
540 return -EFAULT;
541
542 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
543 || ts.tv_nsec >= NSEC_PER_SEC))
544 return -EINVAL;
545 nowts = CURRENT_TIME;
546 /* first subtract as jiffies can't be too big */
547 ts.tv_sec -= nowts.tv_sec;
548 if (ts.tv_nsec < nowts.tv_nsec) {
549 ts.tv_nsec += NSEC_PER_SEC;
550 ts.tv_sec--;
551 }
552 ts.tv_nsec -= nowts.tv_nsec;
553 if (ts.tv_sec < 0)
554 return 0;
555
556 timeout = timespec_to_jiffies(&ts) + 1;
557 } else
558 return MAX_SCHEDULE_TIMEOUT;
559
560 return timeout;
561 }
562
563 static void remove_notification(struct mqueue_inode_info *info)
564 {
565 if (info->notify_owner != 0 &&
566 info->notify.sigev_notify == SIGEV_THREAD) {
567 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
568 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
569 }
570 info->notify_owner = 0;
571 }
572
573 static int mq_attr_ok(struct mq_attr *attr)
574 {
575 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
576 return 0;
577 if (capable(CAP_SYS_RESOURCE)) {
578 if (attr->mq_maxmsg > HARD_MSGMAX)
579 return 0;
580 } else {
581 if (attr->mq_maxmsg > msg_max ||
582 attr->mq_msgsize > msgsize_max)
583 return 0;
584 }
585 /* check for overflow */
586 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
587 return 0;
588 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
589 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
590 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
591 return 0;
592 return 1;
593 }
594
595 /*
596 * Invoked when creating a new queue via sys_mq_open
597 */
598 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
599 int oflag, mode_t mode, struct mq_attr __user *u_attr)
600 {
601 struct file *filp;
602 struct mq_attr attr;
603 int ret;
604
605 if (u_attr != NULL) {
606 if (copy_from_user(&attr, u_attr, sizeof(attr)))
607 return ERR_PTR(-EFAULT);
608 if (!mq_attr_ok(&attr))
609 return ERR_PTR(-EINVAL);
610 /* store for use during create */
611 dentry->d_fsdata = &attr;
612 }
613
614 mode &= ~current->fs->umask;
615 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
616 dentry->d_fsdata = NULL;
617 if (ret)
618 return ERR_PTR(ret);
619
620 filp = dentry_open(dentry, mqueue_mnt, oflag);
621 if (!IS_ERR(filp))
622 dget(dentry);
623
624 return filp;
625 }
626
627 /* Opens existing queue */
628 static struct file *do_open(struct dentry *dentry, int oflag)
629 {
630 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
631 MAY_READ | MAY_WRITE };
632 struct file *filp;
633
634 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
635 return ERR_PTR(-EINVAL);
636
637 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
638 return ERR_PTR(-EACCES);
639
640 filp = dentry_open(dentry, mqueue_mnt, oflag);
641
642 if (!IS_ERR(filp))
643 dget(dentry);
644
645 return filp;
646 }
647
648 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
649 struct mq_attr __user *u_attr)
650 {
651 struct dentry *dentry;
652 struct file *filp;
653 char *name;
654 int fd, error;
655
656 if (IS_ERR(name = getname(u_name)))
657 return PTR_ERR(name);
658
659 fd = get_unused_fd();
660 if (fd < 0)
661 goto out_putname;
662
663 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
664 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
665 if (IS_ERR(dentry)) {
666 error = PTR_ERR(dentry);
667 goto out_err;
668 }
669 mntget(mqueue_mnt);
670
671 if (oflag & O_CREAT) {
672 if (dentry->d_inode) { /* entry already exists */
673 filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
674 do_open(dentry, oflag);
675 } else {
676 filp = do_create(mqueue_mnt->mnt_root, dentry,
677 oflag, mode, u_attr);
678 }
679 } else
680 filp = (dentry->d_inode) ? do_open(dentry, oflag) :
681 ERR_PTR(-ENOENT);
682
683 dput(dentry);
684
685 if (IS_ERR(filp)) {
686 error = PTR_ERR(filp);
687 goto out_putfd;
688 }
689
690 set_close_on_exec(fd, 1);
691 fd_install(fd, filp);
692 goto out_upsem;
693
694 out_putfd:
695 mntput(mqueue_mnt);
696 put_unused_fd(fd);
697 out_err:
698 fd = error;
699 out_upsem:
700 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
701 out_putname:
702 putname(name);
703 return fd;
704 }
705
706 asmlinkage long sys_mq_unlink(const char __user *u_name)
707 {
708 int err;
709 char *name;
710 struct dentry *dentry;
711 struct inode *inode = NULL;
712
713 name = getname(u_name);
714 if (IS_ERR(name))
715 return PTR_ERR(name);
716
717 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
718 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
719 if (IS_ERR(dentry)) {
720 err = PTR_ERR(dentry);
721 goto out_unlock;
722 }
723
724 if (!dentry->d_inode) {
725 err = -ENOENT;
726 goto out_err;
727 }
728
729 inode = dentry->d_inode;
730 if (inode)
731 atomic_inc(&inode->i_count);
732
733 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
734 out_err:
735 dput(dentry);
736
737 out_unlock:
738 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
739 putname(name);
740 if (inode)
741 iput(inode);
742
743 return err;
744 }
745
746 /* Pipelined send and receive functions.
747 *
748 * If a receiver finds no waiting message, then it registers itself in the
749 * list of waiting receivers. A sender checks that list before adding the new
750 * message into the message array. If there is a waiting receiver, then it
751 * bypasses the message array and directly hands the message over to the
752 * receiver.
753 * The receiver accepts the message and returns without grabbing the queue
754 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
755 * are necessary. The same algorithm is used for sysv semaphores, see
756 * ipc/sem.c fore more details.
757 *
758 * The same algorithm is used for senders.
759 */
760
761 /* pipelined_send() - send a message directly to the task waiting in
762 * sys_mq_timedreceive() (without inserting message into a queue).
763 */
764 static inline void pipelined_send(struct mqueue_inode_info *info,
765 struct msg_msg *message,
766 struct ext_wait_queue *receiver)
767 {
768 receiver->msg = message;
769 list_del(&receiver->list);
770 receiver->state = STATE_PENDING;
771 wake_up_process(receiver->task);
772 smp_wmb();
773 receiver->state = STATE_READY;
774 }
775
776 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
777 * gets its message and put to the queue (we have one free place for sure). */
778 static inline void pipelined_receive(struct mqueue_inode_info *info)
779 {
780 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
781
782 if (!sender) {
783 /* for poll */
784 wake_up_interruptible(&info->wait_q);
785 return;
786 }
787 msg_insert(sender->msg, info);
788 list_del(&sender->list);
789 sender->state = STATE_PENDING;
790 wake_up_process(sender->task);
791 smp_wmb();
792 sender->state = STATE_READY;
793 }
794
795 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
796 size_t msg_len, unsigned int msg_prio,
797 const struct timespec __user *u_abs_timeout)
798 {
799 struct file *filp;
800 struct inode *inode;
801 struct ext_wait_queue wait;
802 struct ext_wait_queue *receiver;
803 struct msg_msg *msg_ptr;
804 struct mqueue_inode_info *info;
805 long timeout;
806 int ret;
807
808 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
809 return -EINVAL;
810
811 timeout = prepare_timeout(u_abs_timeout);
812
813 ret = -EBADF;
814 filp = fget(mqdes);
815 if (unlikely(!filp))
816 goto out;
817
818 inode = filp->f_dentry->d_inode;
819 if (unlikely(filp->f_op != &mqueue_file_operations))
820 goto out_fput;
821 info = MQUEUE_I(inode);
822
823 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
824 goto out_fput;
825
826 if (unlikely(msg_len > info->attr.mq_msgsize)) {
827 ret = -EMSGSIZE;
828 goto out_fput;
829 }
830
831 /* First try to allocate memory, before doing anything with
832 * existing queues. */
833 msg_ptr = load_msg(u_msg_ptr, msg_len);
834 if (IS_ERR(msg_ptr)) {
835 ret = PTR_ERR(msg_ptr);
836 goto out_fput;
837 }
838 msg_ptr->m_ts = msg_len;
839 msg_ptr->m_type = msg_prio;
840
841 spin_lock(&info->lock);
842
843 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
844 if (filp->f_flags & O_NONBLOCK) {
845 spin_unlock(&info->lock);
846 ret = -EAGAIN;
847 } else if (unlikely(timeout < 0)) {
848 spin_unlock(&info->lock);
849 ret = timeout;
850 } else {
851 wait.task = current;
852 wait.msg = (void *) msg_ptr;
853 wait.state = STATE_NONE;
854 ret = wq_sleep(info, SEND, timeout, &wait);
855 }
856 if (ret < 0)
857 free_msg(msg_ptr);
858 } else {
859 receiver = wq_get_first_waiter(info, RECV);
860 if (receiver) {
861 pipelined_send(info, msg_ptr, receiver);
862 } else {
863 /* adds message to the queue */
864 msg_insert(msg_ptr, info);
865 __do_notify(info);
866 }
867 inode->i_atime = inode->i_mtime = inode->i_ctime =
868 CURRENT_TIME;
869 spin_unlock(&info->lock);
870 ret = 0;
871 }
872 out_fput:
873 fput(filp);
874 out:
875 return ret;
876 }
877
878 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
879 size_t msg_len, unsigned int __user *u_msg_prio,
880 const struct timespec __user *u_abs_timeout)
881 {
882 long timeout;
883 ssize_t ret;
884 struct msg_msg *msg_ptr;
885 struct file *filp;
886 struct inode *inode;
887 struct mqueue_inode_info *info;
888 struct ext_wait_queue wait;
889
890 timeout = prepare_timeout(u_abs_timeout);
891
892 ret = -EBADF;
893 filp = fget(mqdes);
894 if (unlikely(!filp))
895 goto out;
896
897 inode = filp->f_dentry->d_inode;
898 if (unlikely(filp->f_op != &mqueue_file_operations))
899 goto out_fput;
900 info = MQUEUE_I(inode);
901
902 if (unlikely(!(filp->f_mode & FMODE_READ)))
903 goto out_fput;
904
905 /* checks if buffer is big enough */
906 if (unlikely(msg_len < info->attr.mq_msgsize)) {
907 ret = -EMSGSIZE;
908 goto out_fput;
909 }
910
911 spin_lock(&info->lock);
912 if (info->attr.mq_curmsgs == 0) {
913 if (filp->f_flags & O_NONBLOCK) {
914 spin_unlock(&info->lock);
915 ret = -EAGAIN;
916 msg_ptr = NULL;
917 } else if (unlikely(timeout < 0)) {
918 spin_unlock(&info->lock);
919 ret = timeout;
920 msg_ptr = NULL;
921 } else {
922 wait.task = current;
923 wait.state = STATE_NONE;
924 ret = wq_sleep(info, RECV, timeout, &wait);
925 msg_ptr = wait.msg;
926 }
927 } else {
928 msg_ptr = msg_get(info);
929
930 inode->i_atime = inode->i_mtime = inode->i_ctime =
931 CURRENT_TIME;
932
933 /* There is now free space in queue. */
934 pipelined_receive(info);
935 spin_unlock(&info->lock);
936 ret = 0;
937 }
938 if (ret == 0) {
939 ret = msg_ptr->m_ts;
940
941 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
942 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
943 ret = -EFAULT;
944 }
945 free_msg(msg_ptr);
946 }
947 out_fput:
948 fput(filp);
949 out:
950 return ret;
951 }
952
953 /*
954 * Notes: the case when user wants us to deregister (with NULL as pointer)
955 * and he isn't currently owner of notification, will be silently discarded.
956 * It isn't explicitly defined in the POSIX.
957 */
958 asmlinkage long sys_mq_notify(mqd_t mqdes,
959 const struct sigevent __user *u_notification)
960 {
961 int ret;
962 struct file *filp;
963 struct sock *sock;
964 struct inode *inode;
965 struct sigevent notification;
966 struct mqueue_inode_info *info;
967 struct sk_buff *nc;
968
969 nc = NULL;
970 sock = NULL;
971 if (u_notification != NULL) {
972 if (copy_from_user(&notification, u_notification,
973 sizeof(struct sigevent)))
974 return -EFAULT;
975
976 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
977 notification.sigev_notify != SIGEV_SIGNAL &&
978 notification.sigev_notify != SIGEV_THREAD))
979 return -EINVAL;
980 if (notification.sigev_notify == SIGEV_SIGNAL &&
981 !valid_signal(notification.sigev_signo)) {
982 return -EINVAL;
983 }
984 if (notification.sigev_notify == SIGEV_THREAD) {
985 /* create the notify skb */
986 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
987 ret = -ENOMEM;
988 if (!nc)
989 goto out;
990 ret = -EFAULT;
991 if (copy_from_user(nc->data,
992 notification.sigev_value.sival_ptr,
993 NOTIFY_COOKIE_LEN)) {
994 goto out;
995 }
996
997 /* TODO: add a header? */
998 skb_put(nc, NOTIFY_COOKIE_LEN);
999 /* and attach it to the socket */
1000 retry:
1001 filp = fget(notification.sigev_signo);
1002 ret = -EBADF;
1003 if (!filp)
1004 goto out;
1005 sock = netlink_getsockbyfilp(filp);
1006 fput(filp);
1007 if (IS_ERR(sock)) {
1008 ret = PTR_ERR(sock);
1009 sock = NULL;
1010 goto out;
1011 }
1012
1013 ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
1014 if (ret == 1)
1015 goto retry;
1016 if (ret) {
1017 sock = NULL;
1018 nc = NULL;
1019 goto out;
1020 }
1021 }
1022 }
1023
1024 ret = -EBADF;
1025 filp = fget(mqdes);
1026 if (!filp)
1027 goto out;
1028
1029 inode = filp->f_dentry->d_inode;
1030 if (unlikely(filp->f_op != &mqueue_file_operations))
1031 goto out_fput;
1032 info = MQUEUE_I(inode);
1033
1034 ret = 0;
1035 spin_lock(&info->lock);
1036 if (u_notification == NULL) {
1037 if (info->notify_owner == current->tgid) {
1038 remove_notification(info);
1039 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1040 }
1041 } else if (info->notify_owner != 0) {
1042 ret = -EBUSY;
1043 } else {
1044 switch (notification.sigev_notify) {
1045 case SIGEV_NONE:
1046 info->notify.sigev_notify = SIGEV_NONE;
1047 break;
1048 case SIGEV_THREAD:
1049 info->notify_sock = sock;
1050 info->notify_cookie = nc;
1051 sock = NULL;
1052 nc = NULL;
1053 info->notify.sigev_notify = SIGEV_THREAD;
1054 break;
1055 case SIGEV_SIGNAL:
1056 info->notify.sigev_signo = notification.sigev_signo;
1057 info->notify.sigev_value = notification.sigev_value;
1058 info->notify.sigev_notify = SIGEV_SIGNAL;
1059 break;
1060 }
1061 info->notify_owner = current->tgid;
1062 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1063 }
1064 spin_unlock(&info->lock);
1065 out_fput:
1066 fput(filp);
1067 out:
1068 if (sock) {
1069 netlink_detachskb(sock, nc);
1070 } else if (nc) {
1071 dev_kfree_skb(nc);
1072 }
1073 return ret;
1074 }
1075
1076 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1077 const struct mq_attr __user *u_mqstat,
1078 struct mq_attr __user *u_omqstat)
1079 {
1080 int ret;
1081 struct mq_attr mqstat, omqstat;
1082 struct file *filp;
1083 struct inode *inode;
1084 struct mqueue_inode_info *info;
1085
1086 if (u_mqstat != NULL) {
1087 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1088 return -EFAULT;
1089 if (mqstat.mq_flags & (~O_NONBLOCK))
1090 return -EINVAL;
1091 }
1092
1093 ret = -EBADF;
1094 filp = fget(mqdes);
1095 if (!filp)
1096 goto out;
1097
1098 inode = filp->f_dentry->d_inode;
1099 if (unlikely(filp->f_op != &mqueue_file_operations))
1100 goto out_fput;
1101 info = MQUEUE_I(inode);
1102
1103 spin_lock(&info->lock);
1104
1105 omqstat = info->attr;
1106 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1107 if (u_mqstat) {
1108 if (mqstat.mq_flags & O_NONBLOCK)
1109 filp->f_flags |= O_NONBLOCK;
1110 else
1111 filp->f_flags &= ~O_NONBLOCK;
1112
1113 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1114 }
1115
1116 spin_unlock(&info->lock);
1117
1118 ret = 0;
1119 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1120 sizeof(struct mq_attr)))
1121 ret = -EFAULT;
1122
1123 out_fput:
1124 fput(filp);
1125 out:
1126 return ret;
1127 }
1128
1129 static struct inode_operations mqueue_dir_inode_operations = {
1130 .lookup = simple_lookup,
1131 .create = mqueue_create,
1132 .unlink = mqueue_unlink,
1133 };
1134
1135 static struct file_operations mqueue_file_operations = {
1136 .flush = mqueue_flush_file,
1137 .poll = mqueue_poll_file,
1138 .read = mqueue_read_file,
1139 };
1140
1141 static struct super_operations mqueue_super_ops = {
1142 .alloc_inode = mqueue_alloc_inode,
1143 .destroy_inode = mqueue_destroy_inode,
1144 .statfs = simple_statfs,
1145 .delete_inode = mqueue_delete_inode,
1146 .drop_inode = generic_delete_inode,
1147 };
1148
1149 static struct file_system_type mqueue_fs_type = {
1150 .name = "mqueue",
1151 .get_sb = mqueue_get_sb,
1152 .kill_sb = kill_litter_super,
1153 };
1154
1155 static int msg_max_limit_min = DFLT_MSGMAX;
1156 static int msg_max_limit_max = HARD_MSGMAX;
1157
1158 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1159 static int msg_maxsize_limit_max = INT_MAX;
1160
1161 static ctl_table mq_sysctls[] = {
1162 {
1163 .ctl_name = CTL_QUEUESMAX,
1164 .procname = "queues_max",
1165 .data = &queues_max,
1166 .maxlen = sizeof(int),
1167 .mode = 0644,
1168 .proc_handler = &proc_dointvec,
1169 },
1170 {
1171 .ctl_name = CTL_MSGMAX,
1172 .procname = "msg_max",
1173 .data = &msg_max,
1174 .maxlen = sizeof(int),
1175 .mode = 0644,
1176 .proc_handler = &proc_dointvec_minmax,
1177 .extra1 = &msg_max_limit_min,
1178 .extra2 = &msg_max_limit_max,
1179 },
1180 {
1181 .ctl_name = CTL_MSGSIZEMAX,
1182 .procname = "msgsize_max",
1183 .data = &msgsize_max,
1184 .maxlen = sizeof(int),
1185 .mode = 0644,
1186 .proc_handler = &proc_dointvec_minmax,
1187 .extra1 = &msg_maxsize_limit_min,
1188 .extra2 = &msg_maxsize_limit_max,
1189 },
1190 { .ctl_name = 0 }
1191 };
1192
1193 static ctl_table mq_sysctl_dir[] = {
1194 {
1195 .ctl_name = FS_MQUEUE,
1196 .procname = "mqueue",
1197 .mode = 0555,
1198 .child = mq_sysctls,
1199 },
1200 { .ctl_name = 0 }
1201 };
1202
1203 static ctl_table mq_sysctl_root[] = {
1204 {
1205 .ctl_name = CTL_FS,
1206 .procname = "fs",
1207 .mode = 0555,
1208 .child = mq_sysctl_dir,
1209 },
1210 { .ctl_name = 0 }
1211 };
1212
1213 static int __init init_mqueue_fs(void)
1214 {
1215 int error;
1216
1217 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1218 sizeof(struct mqueue_inode_info), 0,
1219 SLAB_HWCACHE_ALIGN, init_once, NULL);
1220 if (mqueue_inode_cachep == NULL)
1221 return -ENOMEM;
1222
1223 /* ignore failues - they are not fatal */
1224 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1225
1226 error = register_filesystem(&mqueue_fs_type);
1227 if (error)
1228 goto out_sysctl;
1229
1230 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1231 error = PTR_ERR(mqueue_mnt);
1232 goto out_filesystem;
1233 }
1234
1235 /* internal initialization - not common for vfs */
1236 queues_count = 0;
1237 spin_lock_init(&mq_lock);
1238
1239 return 0;
1240
1241 out_filesystem:
1242 unregister_filesystem(&mqueue_fs_type);
1243 out_sysctl:
1244 if (mq_sysctl_table)
1245 unregister_sysctl_table(mq_sysctl_table);
1246 if (kmem_cache_destroy(mqueue_inode_cachep)) {
1247 printk(KERN_INFO
1248 "mqueue_inode_cache: not all structures were freed\n");
1249 }
1250 return error;
1251 }
1252
1253 __initcall(init_mqueue_fs);
Linux with added FPC-III support