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[PATCH] cifs: Fix mapping of EMLINK case
[linux-2.6/linux-2.6-openrd.git] / ipc / mqueue.c
blobcb0cd3cf3b5a5d6c8b8c39f074d01a2b77ce58db
1 /*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5 * Michal Wronski (wrona@mat.uni.torun.pl)
6 *
7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
8 * Lockless receive & send, fd based notify:
9 * Manfred Spraul (manfred@colorfullife.com)
10 *
11 * This file is released under the GPL.
12 */
13
14 #include <linux/init.h>
15 #include <linux/pagemap.h>
16 #include <linux/file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include <linux/sysctl.h>
20 #include <linux/poll.h>
21 #include <linux/mqueue.h>
22 #include <linux/msg.h>
23 #include <linux/skbuff.h>
24 #include <linux/netlink.h>
25 #include <linux/syscalls.h>
26 #include <net/sock.h>
27 #include "util.h"
28
29 #define MQUEUE_MAGIC 0x19800202
30 #define DIRENT_SIZE 20
31 #define FILENT_SIZE 80
32
33 #define SEND 0
34 #define RECV 1
35
36 #define STATE_NONE 0
37 #define STATE_PENDING 1
38 #define STATE_READY 2
39
40 /* used by sysctl */
41 #define FS_MQUEUE 1
42 #define CTL_QUEUESMAX 2
43 #define CTL_MSGMAX 3
44 #define CTL_MSGSIZEMAX 4
45
46 /* default values */
47 #define DFLT_QUEUESMAX 256 /* max number of message queues */
48 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
49 #define HARD_MSGMAX (131072/sizeof(void*))
50 #define DFLT_MSGSIZEMAX 8192 /* max message size */
51
52 #define NOTIFY_COOKIE_LEN 32
53
54 struct ext_wait_queue { /* queue of sleeping tasks */
55 struct task_struct *task;
56 struct list_head list;
57 struct msg_msg *msg; /* ptr of loaded message */
58 int state; /* one of STATE_* values */
59 };
60
61 struct mqueue_inode_info {
62 spinlock_t lock;
63 struct inode vfs_inode;
64 wait_queue_head_t wait_q;
65
66 struct msg_msg **messages;
67 struct mq_attr attr;
68
69 struct sigevent notify;
70 pid_t notify_owner;
71 struct user_struct *user; /* user who created, for accouting */
72 struct sock *notify_sock;
73 struct sk_buff *notify_cookie;
74
75 /* for tasks waiting for free space and messages, respectively */
76 struct ext_wait_queue e_wait_q[2];
77
78 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
79 };
80
81 static struct inode_operations mqueue_dir_inode_operations;
82 static struct file_operations mqueue_file_operations;
83 static struct super_operations mqueue_super_ops;
84 static void remove_notification(struct mqueue_inode_info *info);
85
86 static spinlock_t mq_lock;
87 static kmem_cache_t *mqueue_inode_cachep;
88 static struct vfsmount *mqueue_mnt;
89
90 static unsigned int queues_count;
91 static unsigned int queues_max = DFLT_QUEUESMAX;
92 static unsigned int msg_max = DFLT_MSGMAX;
93 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
94
95 static struct ctl_table_header * mq_sysctl_table;
96
97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
98 {
99 return container_of(inode, struct mqueue_inode_info, vfs_inode);
100 }
101
102 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
103 struct mq_attr *attr)
104 {
105 struct inode *inode;
106
107 inode = new_inode(sb);
108 if (inode) {
109 inode->i_mode = mode;
110 inode->i_uid = current->fsuid;
111 inode->i_gid = current->fsgid;
112 inode->i_blksize = PAGE_CACHE_SIZE;
113 inode->i_blocks = 0;
114 inode->i_mtime = inode->i_ctime = inode->i_atime =
115 CURRENT_TIME;
116
117 if (S_ISREG(mode)) {
118 struct mqueue_inode_info *info;
119 struct task_struct *p = current;
120 struct user_struct *u = p->user;
121 unsigned long mq_bytes, mq_msg_tblsz;
122
123 inode->i_fop = &mqueue_file_operations;
124 inode->i_size = FILENT_SIZE;
125 /* mqueue specific info */
126 info = MQUEUE_I(inode);
127 spin_lock_init(&info->lock);
128 init_waitqueue_head(&info->wait_q);
129 INIT_LIST_HEAD(&info->e_wait_q[0].list);
130 INIT_LIST_HEAD(&info->e_wait_q[1].list);
131 info->messages = NULL;
132 info->notify_owner = 0;
133 info->qsize = 0;
134 info->user = NULL; /* set when all is ok */
135 memset(&info->attr, 0, sizeof(info->attr));
136 info->attr.mq_maxmsg = DFLT_MSGMAX;
137 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
138 if (attr) {
139 info->attr.mq_maxmsg = attr->mq_maxmsg;
140 info->attr.mq_msgsize = attr->mq_msgsize;
141 }
142 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
143 mq_bytes = (mq_msg_tblsz +
144 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
145
146 spin_lock(&mq_lock);
147 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
148 u->mq_bytes + mq_bytes >
149 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
150 spin_unlock(&mq_lock);
151 goto out_inode;
152 }
153 u->mq_bytes += mq_bytes;
154 spin_unlock(&mq_lock);
155
156 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
157 if (!info->messages) {
158 spin_lock(&mq_lock);
159 u->mq_bytes -= mq_bytes;
160 spin_unlock(&mq_lock);
161 goto out_inode;
162 }
163 /* all is ok */
164 info->user = get_uid(u);
165 } else if (S_ISDIR(mode)) {
166 inode->i_nlink++;
167 /* Some things misbehave if size == 0 on a directory */
168 inode->i_size = 2 * DIRENT_SIZE;
169 inode->i_op = &mqueue_dir_inode_operations;
170 inode->i_fop = &simple_dir_operations;
171 }
172 }
173 return inode;
174 out_inode:
175 make_bad_inode(inode);
176 iput(inode);
177 return NULL;
178 }
179
180 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
181 {
182 struct inode *inode;
183
184 sb->s_blocksize = PAGE_CACHE_SIZE;
185 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
186 sb->s_magic = MQUEUE_MAGIC;
187 sb->s_op = &mqueue_super_ops;
188
189 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
190 if (!inode)
191 return -ENOMEM;
192
193 sb->s_root = d_alloc_root(inode);
194 if (!sb->s_root) {
195 iput(inode);
196 return -ENOMEM;
197 }
198
199 return 0;
200 }
201
202 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
203 int flags, const char *dev_name,
204 void *data)
205 {
206 return get_sb_single(fs_type, flags, data, mqueue_fill_super);
207 }
208
209 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
210 {
211 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
212
213 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
214 SLAB_CTOR_CONSTRUCTOR)
215 inode_init_once(&p->vfs_inode);
216 }
217
218 static struct inode *mqueue_alloc_inode(struct super_block *sb)
219 {
220 struct mqueue_inode_info *ei;
221
222 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
223 if (!ei)
224 return NULL;
225 return &ei->vfs_inode;
226 }
227
228 static void mqueue_destroy_inode(struct inode *inode)
229 {
230 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
231 }
232
233 static void mqueue_delete_inode(struct inode *inode)
234 {
235 struct mqueue_inode_info *info;
236 struct user_struct *user;
237 unsigned long mq_bytes;
238 int i;
239
240 if (S_ISDIR(inode->i_mode)) {
241 clear_inode(inode);
242 return;
243 }
244 info = MQUEUE_I(inode);
245 spin_lock(&info->lock);
246 for (i = 0; i < info->attr.mq_curmsgs; i++)
247 free_msg(info->messages[i]);
248 kfree(info->messages);
249 spin_unlock(&info->lock);
250
251 clear_inode(inode);
252
253 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
254 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
255 user = info->user;
256 if (user) {
257 spin_lock(&mq_lock);
258 user->mq_bytes -= mq_bytes;
259 queues_count--;
260 spin_unlock(&mq_lock);
261 free_uid(user);
262 }
263 }
264
265 static int mqueue_create(struct inode *dir, struct dentry *dentry,
266 int mode, struct nameidata *nd)
267 {
268 struct inode *inode;
269 struct mq_attr *attr = dentry->d_fsdata;
270 int error;
271
272 spin_lock(&mq_lock);
273 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
274 error = -ENOSPC;
275 goto out_lock;
276 }
277 queues_count++;
278 spin_unlock(&mq_lock);
279
280 inode = mqueue_get_inode(dir->i_sb, mode, attr);
281 if (!inode) {
282 error = -ENOMEM;
283 spin_lock(&mq_lock);
284 queues_count--;
285 goto out_lock;
286 }
287
288 dir->i_size += DIRENT_SIZE;
289 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
290
291 d_instantiate(dentry, inode);
292 dget(dentry);
293 return 0;
294 out_lock:
295 spin_unlock(&mq_lock);
296 return error;
297 }
298
299 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
300 {
301 struct inode *inode = dentry->d_inode;
302
303 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
304 dir->i_size -= DIRENT_SIZE;
305 inode->i_nlink--;
306 dput(dentry);
307 return 0;
308 }
309
310 /*
311 * This is routine for system read from queue file.
312 * To avoid mess with doing here some sort of mq_receive we allow
313 * to read only queue size & notification info (the only values
314 * that are interesting from user point of view and aren't accessible
315 * through std routines)
316 */
317 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
318 size_t count, loff_t * off)
319 {
320 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
321 char buffer[FILENT_SIZE];
322 size_t slen;
323 loff_t o;
324
325 if (!count)
326 return 0;
327
328 spin_lock(&info->lock);
329 snprintf(buffer, sizeof(buffer),
330 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
331 info->qsize,
332 info->notify_owner ? info->notify.sigev_notify : 0,
333 (info->notify_owner &&
334 info->notify.sigev_notify == SIGEV_SIGNAL) ?
335 info->notify.sigev_signo : 0,
336 info->notify_owner);
337 spin_unlock(&info->lock);
338 buffer[sizeof(buffer)-1] = '\0';
339 slen = strlen(buffer)+1;
340
341 o = *off;
342 if (o > slen)
343 return 0;
344
345 if (o + count > slen)
346 count = slen - o;
347
348 if (copy_to_user(u_data, buffer + o, count))
349 return -EFAULT;
350
351 *off = o + count;
352 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
353 return count;
354 }
355
356 static int mqueue_flush_file(struct file *filp)
357 {
358 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
359
360 spin_lock(&info->lock);
361 if (current->tgid == info->notify_owner)
362 remove_notification(info);
363
364 spin_unlock(&info->lock);
365 return 0;
366 }
367
368 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
369 {
370 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
371 int retval = 0;
372
373 poll_wait(filp, &info->wait_q, poll_tab);
374
375 spin_lock(&info->lock);
376 if (info->attr.mq_curmsgs)
377 retval = POLLIN | POLLRDNORM;
378
379 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
380 retval |= POLLOUT | POLLWRNORM;
381 spin_unlock(&info->lock);
382
383 return retval;
384 }
385
386 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
387 static void wq_add(struct mqueue_inode_info *info, int sr,
388 struct ext_wait_queue *ewp)
389 {
390 struct ext_wait_queue *walk;
391
392 ewp->task = current;
393
394 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
395 if (walk->task->static_prio <= current->static_prio) {
396 list_add_tail(&ewp->list, &walk->list);
397 return;
398 }
399 }
400 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
401 }
402
403 /*
404 * Puts current task to sleep. Caller must hold queue lock. After return
405 * lock isn't held.
406 * sr: SEND or RECV
407 */
408 static int wq_sleep(struct mqueue_inode_info *info, int sr,
409 long timeout, struct ext_wait_queue *ewp)
410 {
411 int retval;
412 signed long time;
413
414 wq_add(info, sr, ewp);
415
416 for (;;) {
417 set_current_state(TASK_INTERRUPTIBLE);
418
419 spin_unlock(&info->lock);
420 time = schedule_timeout(timeout);
421
422 while (ewp->state == STATE_PENDING)
423 cpu_relax();
424
425 if (ewp->state == STATE_READY) {
426 retval = 0;
427 goto out;
428 }
429 spin_lock(&info->lock);
430 if (ewp->state == STATE_READY) {
431 retval = 0;
432 goto out_unlock;
433 }
434 if (signal_pending(current)) {
435 retval = -ERESTARTSYS;
436 break;
437 }
438 if (time == 0) {
439 retval = -ETIMEDOUT;
440 break;
441 }
442 }
443 list_del(&ewp->list);
444 out_unlock:
445 spin_unlock(&info->lock);
446 out:
447 return retval;
448 }
449
450 /*
451 * Returns waiting task that should be serviced first or NULL if none exists
452 */
453 static struct ext_wait_queue *wq_get_first_waiter(
454 struct mqueue_inode_info *info, int sr)
455 {
456 struct list_head *ptr;
457
458 ptr = info->e_wait_q[sr].list.prev;
459 if (ptr == &info->e_wait_q[sr].list)
460 return NULL;
461 return list_entry(ptr, struct ext_wait_queue, list);
462 }
463
464 /* Auxiliary functions to manipulate messages' list */
465 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
466 {
467 int k;
468
469 k = info->attr.mq_curmsgs - 1;
470 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
471 info->messages[k + 1] = info->messages[k];
472 k--;
473 }
474 info->attr.mq_curmsgs++;
475 info->qsize += ptr->m_ts;
476 info->messages[k + 1] = ptr;
477 }
478
479 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
480 {
481 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
482 return info->messages[info->attr.mq_curmsgs];
483 }
484
485 static inline void set_cookie(struct sk_buff *skb, char code)
486 {
487 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
488 }
489
490 /*
491 * The next function is only to split too long sys_mq_timedsend
492 */
493 static void __do_notify(struct mqueue_inode_info *info)
494 {
495 /* notification
496 * invoked when there is registered process and there isn't process
497 * waiting synchronously for message AND state of queue changed from
498 * empty to not empty. Here we are sure that no one is waiting
499 * synchronously. */
500 if (info->notify_owner &&
501 info->attr.mq_curmsgs == 1) {
502 struct siginfo sig_i;
503 switch (info->notify.sigev_notify) {
504 case SIGEV_NONE:
505 break;
506 case SIGEV_SIGNAL:
507 /* sends signal */
508
509 sig_i.si_signo = info->notify.sigev_signo;
510 sig_i.si_errno = 0;
511 sig_i.si_code = SI_MESGQ;
512 sig_i.si_value = info->notify.sigev_value;
513 sig_i.si_pid = current->tgid;
514 sig_i.si_uid = current->uid;
515
516 kill_proc_info(info->notify.sigev_signo,
517 &sig_i, info->notify_owner);
518 break;
519 case SIGEV_THREAD:
520 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
521 netlink_sendskb(info->notify_sock,
522 info->notify_cookie, 0);
523 break;
524 }
525 /* after notification unregisters process */
526 info->notify_owner = 0;
527 }
528 wake_up(&info->wait_q);
529 }
530
531 static long prepare_timeout(const struct timespec __user *u_arg)
532 {
533 struct timespec ts, nowts;
534 long timeout;
535
536 if (u_arg) {
537 if (unlikely(copy_from_user(&ts, u_arg,
538 sizeof(struct timespec))))
539 return -EFAULT;
540
541 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
542 || ts.tv_nsec >= NSEC_PER_SEC))
543 return -EINVAL;
544 nowts = CURRENT_TIME;
545 /* first subtract as jiffies can't be too big */
546 ts.tv_sec -= nowts.tv_sec;
547 if (ts.tv_nsec < nowts.tv_nsec) {
548 ts.tv_nsec += NSEC_PER_SEC;
549 ts.tv_sec--;
550 }
551 ts.tv_nsec -= nowts.tv_nsec;
552 if (ts.tv_sec < 0)
553 return 0;
554
555 timeout = timespec_to_jiffies(&ts) + 1;
556 } else
557 return MAX_SCHEDULE_TIMEOUT;
558
559 return timeout;
560 }
561
562 static void remove_notification(struct mqueue_inode_info *info)
563 {
564 if (info->notify_owner != 0 &&
565 info->notify.sigev_notify == SIGEV_THREAD) {
566 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
567 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
568 }
569 info->notify_owner = 0;
570 }
571
572 static int mq_attr_ok(struct mq_attr *attr)
573 {
574 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
575 return 0;
576 if (capable(CAP_SYS_RESOURCE)) {
577 if (attr->mq_maxmsg > HARD_MSGMAX)
578 return 0;
579 } else {
580 if (attr->mq_maxmsg > msg_max ||
581 attr->mq_msgsize > msgsize_max)
582 return 0;
583 }
584 /* check for overflow */
585 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
586 return 0;
587 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
588 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
589 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
590 return 0;
591 return 1;
592 }
593
594 /*
595 * Invoked when creating a new queue via sys_mq_open
596 */
597 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
598 int oflag, mode_t mode, struct mq_attr __user *u_attr)
599 {
600 struct file *filp;
601 struct mq_attr attr;
602 int ret;
603
604 if (u_attr != NULL) {
605 if (copy_from_user(&attr, u_attr, sizeof(attr)))
606 return ERR_PTR(-EFAULT);
607 if (!mq_attr_ok(&attr))
608 return ERR_PTR(-EINVAL);
609 /* store for use during create */
610 dentry->d_fsdata = &attr;
611 }
612
613 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
614 dentry->d_fsdata = NULL;
615 if (ret)
616 return ERR_PTR(ret);
617
618 filp = dentry_open(dentry, mqueue_mnt, oflag);
619 if (!IS_ERR(filp))
620 dget(dentry);
621
622 return filp;
623 }
624
625 /* Opens existing queue */
626 static struct file *do_open(struct dentry *dentry, int oflag)
627 {
628 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
629 MAY_READ | MAY_WRITE };
630 struct file *filp;
631
632 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
633 return ERR_PTR(-EINVAL);
634
635 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
636 return ERR_PTR(-EACCES);
637
638 filp = dentry_open(dentry, mqueue_mnt, oflag);
639
640 if (!IS_ERR(filp))
641 dget(dentry);
642
643 return filp;
644 }
645
646 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
647 struct mq_attr __user *u_attr)
648 {
649 struct dentry *dentry;
650 struct file *filp;
651 char *name;
652 int fd, error;
653
654 if (IS_ERR(name = getname(u_name)))
655 return PTR_ERR(name);
656
657 fd = get_unused_fd();
658 if (fd < 0)
659 goto out_putname;
660
661 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
662 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
663 if (IS_ERR(dentry)) {
664 error = PTR_ERR(dentry);
665 goto out_err;
666 }
667 mntget(mqueue_mnt);
668
669 if (oflag & O_CREAT) {
670 if (dentry->d_inode) { /* entry already exists */
671 filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
672 do_open(dentry, oflag);
673 } else {
674 filp = do_create(mqueue_mnt->mnt_root, dentry,
675 oflag, mode, u_attr);
676 }
677 } else
678 filp = (dentry->d_inode) ? do_open(dentry, oflag) :
679 ERR_PTR(-ENOENT);
680
681 dput(dentry);
682
683 if (IS_ERR(filp)) {
684 error = PTR_ERR(filp);
685 goto out_putfd;
686 }
687
688 set_close_on_exec(fd, 1);
689 fd_install(fd, filp);
690 goto out_upsem;
691
692 out_putfd:
693 mntput(mqueue_mnt);
694 put_unused_fd(fd);
695 out_err:
696 fd = error;
697 out_upsem:
698 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
699 out_putname:
700 putname(name);
701 return fd;
702 }
703
704 asmlinkage long sys_mq_unlink(const char __user *u_name)
705 {
706 int err;
707 char *name;
708 struct dentry *dentry;
709 struct inode *inode = NULL;
710
711 name = getname(u_name);
712 if (IS_ERR(name))
713 return PTR_ERR(name);
714
715 down(&mqueue_mnt->mnt_root->d_inode->i_sem);
716 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
717 if (IS_ERR(dentry)) {
718 err = PTR_ERR(dentry);
719 goto out_unlock;
720 }
721
722 if (!dentry->d_inode) {
723 err = -ENOENT;
724 goto out_err;
725 }
726
727 inode = dentry->d_inode;
728 if (inode)
729 atomic_inc(&inode->i_count);
730
731 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
732 out_err:
733 dput(dentry);
734
735 out_unlock:
736 up(&mqueue_mnt->mnt_root->d_inode->i_sem);
737 putname(name);
738 if (inode)
739 iput(inode);
740
741 return err;
742 }
743
744 /* Pipelined send and receive functions.
745 *
746 * If a receiver finds no waiting message, then it registers itself in the
747 * list of waiting receivers. A sender checks that list before adding the new
748 * message into the message array. If there is a waiting receiver, then it
749 * bypasses the message array and directly hands the message over to the
750 * receiver.
751 * The receiver accepts the message and returns without grabbing the queue
752 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
753 * are necessary. The same algorithm is used for sysv semaphores, see
754 * ipc/sem.c fore more details.
755 *
756 * The same algorithm is used for senders.
757 */
758
759 /* pipelined_send() - send a message directly to the task waiting in
760 * sys_mq_timedreceive() (without inserting message into a queue).
761 */
762 static inline void pipelined_send(struct mqueue_inode_info *info,
763 struct msg_msg *message,
764 struct ext_wait_queue *receiver)
765 {
766 receiver->msg = message;
767 list_del(&receiver->list);
768 receiver->state = STATE_PENDING;
769 wake_up_process(receiver->task);
770 wmb();
771 receiver->state = STATE_READY;
772 }
773
774 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
775 * gets its message and put to the queue (we have one free place for sure). */
776 static inline void pipelined_receive(struct mqueue_inode_info *info)
777 {
778 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
779
780 if (!sender) {
781 /* for poll */
782 wake_up_interruptible(&info->wait_q);
783 return;
784 }
785 msg_insert(sender->msg, info);
786 list_del(&sender->list);
787 sender->state = STATE_PENDING;
788 wake_up_process(sender->task);
789 wmb();
790 sender->state = STATE_READY;
791 }
792
793 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
794 size_t msg_len, unsigned int msg_prio,
795 const struct timespec __user *u_abs_timeout)
796 {
797 struct file *filp;
798 struct inode *inode;
799 struct ext_wait_queue wait;
800 struct ext_wait_queue *receiver;
801 struct msg_msg *msg_ptr;
802 struct mqueue_inode_info *info;
803 long timeout;
804 int ret;
805
806 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
807 return -EINVAL;
808
809 timeout = prepare_timeout(u_abs_timeout);
810
811 ret = -EBADF;
812 filp = fget(mqdes);
813 if (unlikely(!filp))
814 goto out;
815
816 inode = filp->f_dentry->d_inode;
817 if (unlikely(filp->f_op != &mqueue_file_operations))
818 goto out_fput;
819 info = MQUEUE_I(inode);
820
821 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
822 goto out_fput;
823
824 if (unlikely(msg_len > info->attr.mq_msgsize)) {
825 ret = -EMSGSIZE;
826 goto out_fput;
827 }
828
829 /* First try to allocate memory, before doing anything with
830 * existing queues. */
831 msg_ptr = load_msg(u_msg_ptr, msg_len);
832 if (IS_ERR(msg_ptr)) {
833 ret = PTR_ERR(msg_ptr);
834 goto out_fput;
835 }
836 msg_ptr->m_ts = msg_len;
837 msg_ptr->m_type = msg_prio;
838
839 spin_lock(&info->lock);
840
841 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
842 if (filp->f_flags & O_NONBLOCK) {
843 spin_unlock(&info->lock);
844 ret = -EAGAIN;
845 } else if (unlikely(timeout < 0)) {
846 spin_unlock(&info->lock);
847 ret = timeout;
848 } else {
849 wait.task = current;
850 wait.msg = (void *) msg_ptr;
851 wait.state = STATE_NONE;
852 ret = wq_sleep(info, SEND, timeout, &wait);
853 }
854 if (ret < 0)
855 free_msg(msg_ptr);
856 } else {
857 receiver = wq_get_first_waiter(info, RECV);
858 if (receiver) {
859 pipelined_send(info, msg_ptr, receiver);
860 } else {
861 /* adds message to the queue */
862 msg_insert(msg_ptr, info);
863 __do_notify(info);
864 }
865 inode->i_atime = inode->i_mtime = inode->i_ctime =
866 CURRENT_TIME;
867 spin_unlock(&info->lock);
868 ret = 0;
869 }
870 out_fput:
871 fput(filp);
872 out:
873 return ret;
874 }
875
876 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
877 size_t msg_len, unsigned int __user *u_msg_prio,
878 const struct timespec __user *u_abs_timeout)
879 {
880 long timeout;
881 ssize_t ret;
882 struct msg_msg *msg_ptr;
883 struct file *filp;
884 struct inode *inode;
885 struct mqueue_inode_info *info;
886 struct ext_wait_queue wait;
887
888 timeout = prepare_timeout(u_abs_timeout);
889
890 ret = -EBADF;
891 filp = fget(mqdes);
892 if (unlikely(!filp))
893 goto out;
894
895 inode = filp->f_dentry->d_inode;
896 if (unlikely(filp->f_op != &mqueue_file_operations))
897 goto out_fput;
898 info = MQUEUE_I(inode);
899
900 if (unlikely(!(filp->f_mode & FMODE_READ)))
901 goto out_fput;
902
903 /* checks if buffer is big enough */
904 if (unlikely(msg_len < info->attr.mq_msgsize)) {
905 ret = -EMSGSIZE;
906 goto out_fput;
907 }
908
909 spin_lock(&info->lock);
910 if (info->attr.mq_curmsgs == 0) {
911 if (filp->f_flags & O_NONBLOCK) {
912 spin_unlock(&info->lock);
913 ret = -EAGAIN;
914 msg_ptr = NULL;
915 } else if (unlikely(timeout < 0)) {
916 spin_unlock(&info->lock);
917 ret = timeout;
918 msg_ptr = NULL;
919 } else {
920 wait.task = current;
921 wait.state = STATE_NONE;
922 ret = wq_sleep(info, RECV, timeout, &wait);
923 msg_ptr = wait.msg;
924 }
925 } else {
926 msg_ptr = msg_get(info);
927
928 inode->i_atime = inode->i_mtime = inode->i_ctime =
929 CURRENT_TIME;
930
931 /* There is now free space in queue. */
932 pipelined_receive(info);
933 spin_unlock(&info->lock);
934 ret = 0;
935 }
936 if (ret == 0) {
937 ret = msg_ptr->m_ts;
938
939 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
940 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
941 ret = -EFAULT;
942 }
943 free_msg(msg_ptr);
944 }
945 out_fput:
946 fput(filp);
947 out:
948 return ret;
949 }
950
951 /*
952 * Notes: the case when user wants us to deregister (with NULL as pointer)
953 * and he isn't currently owner of notification, will be silently discarded.
954 * It isn't explicitly defined in the POSIX.
955 */
956 asmlinkage long sys_mq_notify(mqd_t mqdes,
957 const struct sigevent __user *u_notification)
958 {
959 int ret;
960 struct file *filp;
961 struct sock *sock;
962 struct inode *inode;
963 struct sigevent notification;
964 struct mqueue_inode_info *info;
965 struct sk_buff *nc;
966
967 nc = NULL;
968 sock = NULL;
969 if (u_notification != NULL) {
970 if (copy_from_user(&notification, u_notification,
971 sizeof(struct sigevent)))
972 return -EFAULT;
973
974 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
975 notification.sigev_notify != SIGEV_SIGNAL &&
976 notification.sigev_notify != SIGEV_THREAD))
977 return -EINVAL;
978 if (notification.sigev_notify == SIGEV_SIGNAL &&
979 (notification.sigev_signo < 0 ||
980 notification.sigev_signo > _NSIG)) {
981 return -EINVAL;
982 }
983 if (notification.sigev_notify == SIGEV_THREAD) {
984 /* create the notify skb */
985 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
986 ret = -ENOMEM;
987 if (!nc)
988 goto out;
989 ret = -EFAULT;
990 if (copy_from_user(nc->data,
991 notification.sigev_value.sival_ptr,
992 NOTIFY_COOKIE_LEN)) {
993 goto out;
994 }
995
996 /* TODO: add a header? */
997 skb_put(nc, NOTIFY_COOKIE_LEN);
998 /* and attach it to the socket */
999 retry:
1000 filp = fget(notification.sigev_signo);
1001 ret = -EBADF;
1002 if (!filp)
1003 goto out;
1004 sock = netlink_getsockbyfilp(filp);
1005 fput(filp);
1006 if (IS_ERR(sock)) {
1007 ret = PTR_ERR(sock);
1008 sock = NULL;
1009 goto out;
1010 }
1011
1012 ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
1013 if (ret == 1)
1014 goto retry;
1015 if (ret) {
1016 sock = NULL;
1017 nc = NULL;
1018 goto out;
1019 }
1020 }
1021 }
1022
1023 ret = -EBADF;
1024 filp = fget(mqdes);
1025 if (!filp)
1026 goto out;
1027
1028 inode = filp->f_dentry->d_inode;
1029 if (unlikely(filp->f_op != &mqueue_file_operations))
1030 goto out_fput;
1031 info = MQUEUE_I(inode);
1032
1033 ret = 0;
1034 spin_lock(&info->lock);
1035 if (u_notification == NULL) {
1036 if (info->notify_owner == current->tgid) {
1037 remove_notification(info);
1038 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1039 }
1040 } else if (info->notify_owner != 0) {
1041 ret = -EBUSY;
1042 } else {
1043 switch (notification.sigev_notify) {
1044 case SIGEV_NONE:
1045 info->notify.sigev_notify = SIGEV_NONE;
1046 break;
1047 case SIGEV_THREAD:
1048 info->notify_sock = sock;
1049 info->notify_cookie = nc;
1050 sock = NULL;
1051 nc = NULL;
1052 info->notify.sigev_notify = SIGEV_THREAD;
1053 break;
1054 case SIGEV_SIGNAL:
1055 info->notify.sigev_signo = notification.sigev_signo;
1056 info->notify.sigev_value = notification.sigev_value;
1057 info->notify.sigev_notify = SIGEV_SIGNAL;
1058 break;
1059 }
1060 info->notify_owner = current->tgid;
1061 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1062 }
1063 spin_unlock(&info->lock);
1064 out_fput:
1065 fput(filp);
1066 out:
1067 if (sock) {
1068 netlink_detachskb(sock, nc);
1069 } else if (nc) {
1070 dev_kfree_skb(nc);
1071 }
1072 return ret;
1073 }
1074
1075 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1076 const struct mq_attr __user *u_mqstat,
1077 struct mq_attr __user *u_omqstat)
1078 {
1079 int ret;
1080 struct mq_attr mqstat, omqstat;
1081 struct file *filp;
1082 struct inode *inode;
1083 struct mqueue_inode_info *info;
1084
1085 if (u_mqstat != NULL) {
1086 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1087 return -EFAULT;
1088 if (mqstat.mq_flags & (~O_NONBLOCK))
1089 return -EINVAL;
1090 }
1091
1092 ret = -EBADF;
1093 filp = fget(mqdes);
1094 if (!filp)
1095 goto out;
1096
1097 inode = filp->f_dentry->d_inode;
1098 if (unlikely(filp->f_op != &mqueue_file_operations))
1099 goto out_fput;
1100 info = MQUEUE_I(inode);
1101
1102 spin_lock(&info->lock);
1103
1104 omqstat = info->attr;
1105 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1106 if (u_mqstat) {
1107 if (mqstat.mq_flags & O_NONBLOCK)
1108 filp->f_flags |= O_NONBLOCK;
1109 else
1110 filp->f_flags &= ~O_NONBLOCK;
1111
1112 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1113 }
1114
1115 spin_unlock(&info->lock);
1116
1117 ret = 0;
1118 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1119 sizeof(struct mq_attr)))
1120 ret = -EFAULT;
1121
1122 out_fput:
1123 fput(filp);
1124 out:
1125 return ret;
1126 }
1127
1128 static struct inode_operations mqueue_dir_inode_operations = {
1129 .lookup = simple_lookup,
1130 .create = mqueue_create,
1131 .unlink = mqueue_unlink,
1132 };
1133
1134 static struct file_operations mqueue_file_operations = {
1135 .flush = mqueue_flush_file,
1136 .poll = mqueue_poll_file,
1137 .read = mqueue_read_file,
1138 };
1139
1140 static struct super_operations mqueue_super_ops = {
1141 .alloc_inode = mqueue_alloc_inode,
1142 .destroy_inode = mqueue_destroy_inode,
1143 .statfs = simple_statfs,
1144 .delete_inode = mqueue_delete_inode,
1145 .drop_inode = generic_delete_inode,
1146 };
1147
1148 static struct file_system_type mqueue_fs_type = {
1149 .name = "mqueue",
1150 .get_sb = mqueue_get_sb,
1151 .kill_sb = kill_litter_super,
1152 };
1153
1154 static int msg_max_limit_min = DFLT_MSGMAX;
1155 static int msg_max_limit_max = HARD_MSGMAX;
1156
1157 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1158 static int msg_maxsize_limit_max = INT_MAX;
1159
1160 static ctl_table mq_sysctls[] = {
1161 {
1162 .ctl_name = CTL_QUEUESMAX,
1163 .procname = "queues_max",
1164 .data = &queues_max,
1165 .maxlen = sizeof(int),
1166 .mode = 0644,
1167 .proc_handler = &proc_dointvec,
1168 },
1169 {
1170 .ctl_name = CTL_MSGMAX,
1171 .procname = "msg_max",
1172 .data = &msg_max,
1173 .maxlen = sizeof(int),
1174 .mode = 0644,
1175 .proc_handler = &proc_dointvec_minmax,
1176 .extra1 = &msg_max_limit_min,
1177 .extra2 = &msg_max_limit_max,
1178 },
1179 {
1180 .ctl_name = CTL_MSGSIZEMAX,
1181 .procname = "msgsize_max",
1182 .data = &msgsize_max,
1183 .maxlen = sizeof(int),
1184 .mode = 0644,
1185 .proc_handler = &proc_dointvec_minmax,
1186 .extra1 = &msg_maxsize_limit_min,
1187 .extra2 = &msg_maxsize_limit_max,
1188 },
1189 { .ctl_name = 0 }
1190 };
1191
1192 static ctl_table mq_sysctl_dir[] = {
1193 {
1194 .ctl_name = FS_MQUEUE,
1195 .procname = "mqueue",
1196 .mode = 0555,
1197 .child = mq_sysctls,
1198 },
1199 { .ctl_name = 0 }
1200 };
1201
1202 static ctl_table mq_sysctl_root[] = {
1203 {
1204 .ctl_name = CTL_FS,
1205 .procname = "fs",
1206 .mode = 0555,
1207 .child = mq_sysctl_dir,
1208 },
1209 { .ctl_name = 0 }
1210 };
1211
1212 static int __init init_mqueue_fs(void)
1213 {
1214 int error;
1215
1216 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1217 sizeof(struct mqueue_inode_info), 0,
1218 SLAB_HWCACHE_ALIGN, init_once, NULL);
1219 if (mqueue_inode_cachep == NULL)
1220 return -ENOMEM;
1221
1222 /* ignore failues - they are not fatal */
1223 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1224
1225 error = register_filesystem(&mqueue_fs_type);
1226 if (error)
1227 goto out_sysctl;
1228
1229 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1230 error = PTR_ERR(mqueue_mnt);
1231 goto out_filesystem;
1232 }
1233
1234 /* internal initialization - not common for vfs */
1235 queues_count = 0;
1236 spin_lock_init(&mq_lock);
1237
1238 return 0;
1239
1240 out_filesystem:
1241 unregister_filesystem(&mqueue_fs_type);
1242 out_sysctl:
1243 if (mq_sysctl_table)
1244 unregister_sysctl_table(mq_sysctl_table);
1245 if (kmem_cache_destroy(mqueue_inode_cachep)) {
1246 printk(KERN_INFO
1247 "mqueue_inode_cache: not all structures were freed\n");
1248 }
1249 return error;
1250 }
1251
1252 __initcall(init_mqueue_fs);
linux 2.6 git repository for openrd