Root/ipc/mqueue.c

1/*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5 * Michal Wronski (michal.wronski@gmail.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 * Audit: George Wilson (ltcgcw@us.ibm.com)
12 *
13 * This file is released under the GPL.
14 */
15
16#include <linux/capability.h>
17#include <linux/init.h>
18#include <linux/pagemap.h>
19#include <linux/file.h>
20#include <linux/mount.h>
21#include <linux/namei.h>
22#include <linux/sysctl.h>
23#include <linux/poll.h>
24#include <linux/mqueue.h>
25#include <linux/msg.h>
26#include <linux/skbuff.h>
27#include <linux/vmalloc.h>
28#include <linux/netlink.h>
29#include <linux/syscalls.h>
30#include <linux/audit.h>
31#include <linux/signal.h>
32#include <linux/mutex.h>
33#include <linux/nsproxy.h>
34#include <linux/pid.h>
35#include <linux/ipc_namespace.h>
36#include <linux/user_namespace.h>
37#include <linux/slab.h>
38
39#include <net/sock.h>
40#include "util.h"
41
42#define MQUEUE_MAGIC 0x19800202
43#define DIRENT_SIZE 20
44#define FILENT_SIZE 80
45
46#define SEND 0
47#define RECV 1
48
49#define STATE_NONE 0
50#define STATE_PENDING 1
51#define STATE_READY 2
52
53struct posix_msg_tree_node {
54    struct rb_node rb_node;
55    struct list_head msg_list;
56    int priority;
57};
58
59struct ext_wait_queue { /* queue of sleeping tasks */
60    struct task_struct *task;
61    struct list_head list;
62    struct msg_msg *msg; /* ptr of loaded message */
63    int state; /* one of STATE_* values */
64};
65
66struct mqueue_inode_info {
67    spinlock_t lock;
68    struct inode vfs_inode;
69    wait_queue_head_t wait_q;
70
71    struct rb_root msg_tree;
72    struct posix_msg_tree_node *node_cache;
73    struct mq_attr attr;
74
75    struct sigevent notify;
76    struct pid* notify_owner;
77    struct user_namespace *notify_user_ns;
78    struct user_struct *user; /* user who created, for accounting */
79    struct sock *notify_sock;
80    struct sk_buff *notify_cookie;
81
82    /* for tasks waiting for free space and messages, respectively */
83    struct ext_wait_queue e_wait_q[2];
84
85    unsigned long qsize; /* size of queue in memory (sum of all msgs) */
86};
87
88static const struct inode_operations mqueue_dir_inode_operations;
89static const struct file_operations mqueue_file_operations;
90static const struct super_operations mqueue_super_ops;
91static void remove_notification(struct mqueue_inode_info *info);
92
93static struct kmem_cache *mqueue_inode_cachep;
94
95static struct ctl_table_header * mq_sysctl_table;
96
97static 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/*
103 * This routine should be called with the mq_lock held.
104 */
105static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
106{
107    return get_ipc_ns(inode->i_sb->s_fs_info);
108}
109
110static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
111{
112    struct ipc_namespace *ns;
113
114    spin_lock(&mq_lock);
115    ns = __get_ns_from_inode(inode);
116    spin_unlock(&mq_lock);
117    return ns;
118}
119
120/* Auxiliary functions to manipulate messages' list */
121static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
122{
123    struct rb_node **p, *parent = NULL;
124    struct posix_msg_tree_node *leaf;
125
126    p = &info->msg_tree.rb_node;
127    while (*p) {
128        parent = *p;
129        leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
130
131        if (likely(leaf->priority == msg->m_type))
132            goto insert_msg;
133        else if (msg->m_type < leaf->priority)
134            p = &(*p)->rb_left;
135        else
136            p = &(*p)->rb_right;
137    }
138    if (info->node_cache) {
139        leaf = info->node_cache;
140        info->node_cache = NULL;
141    } else {
142        leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
143        if (!leaf)
144            return -ENOMEM;
145        rb_init_node(&leaf->rb_node);
146        INIT_LIST_HEAD(&leaf->msg_list);
147        info->qsize += sizeof(*leaf);
148    }
149    leaf->priority = msg->m_type;
150    rb_link_node(&leaf->rb_node, parent, p);
151    rb_insert_color(&leaf->rb_node, &info->msg_tree);
152insert_msg:
153    info->attr.mq_curmsgs++;
154    info->qsize += msg->m_ts;
155    list_add_tail(&msg->m_list, &leaf->msg_list);
156    return 0;
157}
158
159static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
160{
161    struct rb_node **p, *parent = NULL;
162    struct posix_msg_tree_node *leaf;
163    struct msg_msg *msg;
164
165try_again:
166    p = &info->msg_tree.rb_node;
167    while (*p) {
168        parent = *p;
169        /*
170         * During insert, low priorities go to the left and high to the
171         * right. On receive, we want the highest priorities first, so
172         * walk all the way to the right.
173         */
174        p = &(*p)->rb_right;
175    }
176    if (!parent) {
177        if (info->attr.mq_curmsgs) {
178            pr_warn_once("Inconsistency in POSIX message queue, "
179                     "no tree element, but supposedly messages "
180                     "should exist!\n");
181            info->attr.mq_curmsgs = 0;
182        }
183        return NULL;
184    }
185    leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
186    if (unlikely(list_empty(&leaf->msg_list))) {
187        pr_warn_once("Inconsistency in POSIX message queue, "
188                 "empty leaf node but we haven't implemented "
189                 "lazy leaf delete!\n");
190        rb_erase(&leaf->rb_node, &info->msg_tree);
191        if (info->node_cache) {
192            info->qsize -= sizeof(*leaf);
193            kfree(leaf);
194        } else {
195            info->node_cache = leaf;
196        }
197        goto try_again;
198    } else {
199        msg = list_first_entry(&leaf->msg_list,
200                       struct msg_msg, m_list);
201        list_del(&msg->m_list);
202        if (list_empty(&leaf->msg_list)) {
203            rb_erase(&leaf->rb_node, &info->msg_tree);
204            if (info->node_cache) {
205                info->qsize -= sizeof(*leaf);
206                kfree(leaf);
207            } else {
208                info->node_cache = leaf;
209            }
210        }
211    }
212    info->attr.mq_curmsgs--;
213    info->qsize -= msg->m_ts;
214    return msg;
215}
216
217static struct inode *mqueue_get_inode(struct super_block *sb,
218        struct ipc_namespace *ipc_ns, umode_t mode,
219        struct mq_attr *attr)
220{
221    struct user_struct *u = current_user();
222    struct inode *inode;
223    int ret = -ENOMEM;
224
225    inode = new_inode(sb);
226    if (!inode)
227        goto err;
228
229    inode->i_ino = get_next_ino();
230    inode->i_mode = mode;
231    inode->i_uid = current_fsuid();
232    inode->i_gid = current_fsgid();
233    inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
234
235    if (S_ISREG(mode)) {
236        struct mqueue_inode_info *info;
237        unsigned long mq_bytes, mq_treesize;
238
239        inode->i_fop = &mqueue_file_operations;
240        inode->i_size = FILENT_SIZE;
241        /* mqueue specific info */
242        info = MQUEUE_I(inode);
243        spin_lock_init(&info->lock);
244        init_waitqueue_head(&info->wait_q);
245        INIT_LIST_HEAD(&info->e_wait_q[0].list);
246        INIT_LIST_HEAD(&info->e_wait_q[1].list);
247        info->notify_owner = NULL;
248        info->notify_user_ns = NULL;
249        info->qsize = 0;
250        info->user = NULL; /* set when all is ok */
251        info->msg_tree = RB_ROOT;
252        info->node_cache = NULL;
253        memset(&info->attr, 0, sizeof(info->attr));
254        info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
255                       ipc_ns->mq_msg_default);
256        info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
257                        ipc_ns->mq_msgsize_default);
258        if (attr) {
259            info->attr.mq_maxmsg = attr->mq_maxmsg;
260            info->attr.mq_msgsize = attr->mq_msgsize;
261        }
262        /*
263         * We used to allocate a static array of pointers and account
264         * the size of that array as well as one msg_msg struct per
265         * possible message into the queue size. That's no longer
266         * accurate as the queue is now an rbtree and will grow and
267         * shrink depending on usage patterns. We can, however, still
268         * account one msg_msg struct per message, but the nodes are
269         * allocated depending on priority usage, and most programs
270         * only use one, or a handful, of priorities. However, since
271         * this is pinned memory, we need to assume worst case, so
272         * that means the min(mq_maxmsg, max_priorities) * struct
273         * posix_msg_tree_node.
274         */
275        mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
276            min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
277            sizeof(struct posix_msg_tree_node);
278
279        mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
280                      info->attr.mq_msgsize);
281
282        spin_lock(&mq_lock);
283        if (u->mq_bytes + mq_bytes < u->mq_bytes ||
284            u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
285            spin_unlock(&mq_lock);
286            /* mqueue_evict_inode() releases info->messages */
287            ret = -EMFILE;
288            goto out_inode;
289        }
290        u->mq_bytes += mq_bytes;
291        spin_unlock(&mq_lock);
292
293        /* all is ok */
294        info->user = get_uid(u);
295    } else if (S_ISDIR(mode)) {
296        inc_nlink(inode);
297        /* Some things misbehave if size == 0 on a directory */
298        inode->i_size = 2 * DIRENT_SIZE;
299        inode->i_op = &mqueue_dir_inode_operations;
300        inode->i_fop = &simple_dir_operations;
301    }
302
303    return inode;
304out_inode:
305    iput(inode);
306err:
307    return ERR_PTR(ret);
308}
309
310static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
311{
312    struct inode *inode;
313    struct ipc_namespace *ns = data;
314
315    sb->s_blocksize = PAGE_CACHE_SIZE;
316    sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
317    sb->s_magic = MQUEUE_MAGIC;
318    sb->s_op = &mqueue_super_ops;
319
320    inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
321    if (IS_ERR(inode))
322        return PTR_ERR(inode);
323
324    sb->s_root = d_make_root(inode);
325    if (!sb->s_root)
326        return -ENOMEM;
327    return 0;
328}
329
330static struct dentry *mqueue_mount(struct file_system_type *fs_type,
331             int flags, const char *dev_name,
332             void *data)
333{
334    if (!(flags & MS_KERNMOUNT))
335        data = current->nsproxy->ipc_ns;
336    return mount_ns(fs_type, flags, data, mqueue_fill_super);
337}
338
339static void init_once(void *foo)
340{
341    struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
342
343    inode_init_once(&p->vfs_inode);
344}
345
346static struct inode *mqueue_alloc_inode(struct super_block *sb)
347{
348    struct mqueue_inode_info *ei;
349
350    ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
351    if (!ei)
352        return NULL;
353    return &ei->vfs_inode;
354}
355
356static void mqueue_i_callback(struct rcu_head *head)
357{
358    struct inode *inode = container_of(head, struct inode, i_rcu);
359    kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
360}
361
362static void mqueue_destroy_inode(struct inode *inode)
363{
364    call_rcu(&inode->i_rcu, mqueue_i_callback);
365}
366
367static void mqueue_evict_inode(struct inode *inode)
368{
369    struct mqueue_inode_info *info;
370    struct user_struct *user;
371    unsigned long mq_bytes, mq_treesize;
372    struct ipc_namespace *ipc_ns;
373    struct msg_msg *msg;
374
375    clear_inode(inode);
376
377    if (S_ISDIR(inode->i_mode))
378        return;
379
380    ipc_ns = get_ns_from_inode(inode);
381    info = MQUEUE_I(inode);
382    spin_lock(&info->lock);
383    while ((msg = msg_get(info)) != NULL)
384        free_msg(msg);
385    kfree(info->node_cache);
386    spin_unlock(&info->lock);
387
388    /* Total amount of bytes accounted for the mqueue */
389    mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
390        min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
391        sizeof(struct posix_msg_tree_node);
392
393    mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
394                  info->attr.mq_msgsize);
395
396    user = info->user;
397    if (user) {
398        spin_lock(&mq_lock);
399        user->mq_bytes -= mq_bytes;
400        /*
401         * get_ns_from_inode() ensures that the
402         * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
403         * to which we now hold a reference, or it is NULL.
404         * We can't put it here under mq_lock, though.
405         */
406        if (ipc_ns)
407            ipc_ns->mq_queues_count--;
408        spin_unlock(&mq_lock);
409        free_uid(user);
410    }
411    if (ipc_ns)
412        put_ipc_ns(ipc_ns);
413}
414
415static int mqueue_create(struct inode *dir, struct dentry *dentry,
416                umode_t mode, bool excl)
417{
418    struct inode *inode;
419    struct mq_attr *attr = dentry->d_fsdata;
420    int error;
421    struct ipc_namespace *ipc_ns;
422
423    spin_lock(&mq_lock);
424    ipc_ns = __get_ns_from_inode(dir);
425    if (!ipc_ns) {
426        error = -EACCES;
427        goto out_unlock;
428    }
429    if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
430        (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
431         !capable(CAP_SYS_RESOURCE))) {
432        error = -ENOSPC;
433        goto out_unlock;
434    }
435    ipc_ns->mq_queues_count++;
436    spin_unlock(&mq_lock);
437
438    inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
439    if (IS_ERR(inode)) {
440        error = PTR_ERR(inode);
441        spin_lock(&mq_lock);
442        ipc_ns->mq_queues_count--;
443        goto out_unlock;
444    }
445
446    put_ipc_ns(ipc_ns);
447    dir->i_size += DIRENT_SIZE;
448    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
449
450    d_instantiate(dentry, inode);
451    dget(dentry);
452    return 0;
453out_unlock:
454    spin_unlock(&mq_lock);
455    if (ipc_ns)
456        put_ipc_ns(ipc_ns);
457    return error;
458}
459
460static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
461{
462      struct inode *inode = dentry->d_inode;
463
464    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
465    dir->i_size -= DIRENT_SIZE;
466      drop_nlink(inode);
467      dput(dentry);
468      return 0;
469}
470
471/*
472* This is routine for system read from queue file.
473* To avoid mess with doing here some sort of mq_receive we allow
474* to read only queue size & notification info (the only values
475* that are interesting from user point of view and aren't accessible
476* through std routines)
477*/
478static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
479                size_t count, loff_t *off)
480{
481    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
482    char buffer[FILENT_SIZE];
483    ssize_t ret;
484
485    spin_lock(&info->lock);
486    snprintf(buffer, sizeof(buffer),
487            "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
488            info->qsize,
489            info->notify_owner ? info->notify.sigev_notify : 0,
490            (info->notify_owner &&
491             info->notify.sigev_notify == SIGEV_SIGNAL) ?
492                info->notify.sigev_signo : 0,
493            pid_vnr(info->notify_owner));
494    spin_unlock(&info->lock);
495    buffer[sizeof(buffer)-1] = '\0';
496
497    ret = simple_read_from_buffer(u_data, count, off, buffer,
498                strlen(buffer));
499    if (ret <= 0)
500        return ret;
501
502    filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
503    return ret;
504}
505
506static int mqueue_flush_file(struct file *filp, fl_owner_t id)
507{
508    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
509
510    spin_lock(&info->lock);
511    if (task_tgid(current) == info->notify_owner)
512        remove_notification(info);
513
514    spin_unlock(&info->lock);
515    return 0;
516}
517
518static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
519{
520    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
521    int retval = 0;
522
523    poll_wait(filp, &info->wait_q, poll_tab);
524
525    spin_lock(&info->lock);
526    if (info->attr.mq_curmsgs)
527        retval = POLLIN | POLLRDNORM;
528
529    if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
530        retval |= POLLOUT | POLLWRNORM;
531    spin_unlock(&info->lock);
532
533    return retval;
534}
535
536/* Adds current to info->e_wait_q[sr] before element with smaller prio */
537static void wq_add(struct mqueue_inode_info *info, int sr,
538            struct ext_wait_queue *ewp)
539{
540    struct ext_wait_queue *walk;
541
542    ewp->task = current;
543
544    list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
545        if (walk->task->static_prio <= current->static_prio) {
546            list_add_tail(&ewp->list, &walk->list);
547            return;
548        }
549    }
550    list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
551}
552
553/*
554 * Puts current task to sleep. Caller must hold queue lock. After return
555 * lock isn't held.
556 * sr: SEND or RECV
557 */
558static int wq_sleep(struct mqueue_inode_info *info, int sr,
559            ktime_t *timeout, struct ext_wait_queue *ewp)
560{
561    int retval;
562    signed long time;
563
564    wq_add(info, sr, ewp);
565
566    for (;;) {
567        set_current_state(TASK_INTERRUPTIBLE);
568
569        spin_unlock(&info->lock);
570        time = schedule_hrtimeout_range_clock(timeout, 0,
571            HRTIMER_MODE_ABS, CLOCK_REALTIME);
572
573        while (ewp->state == STATE_PENDING)
574            cpu_relax();
575
576        if (ewp->state == STATE_READY) {
577            retval = 0;
578            goto out;
579        }
580        spin_lock(&info->lock);
581        if (ewp->state == STATE_READY) {
582            retval = 0;
583            goto out_unlock;
584        }
585        if (signal_pending(current)) {
586            retval = -ERESTARTSYS;
587            break;
588        }
589        if (time == 0) {
590            retval = -ETIMEDOUT;
591            break;
592        }
593    }
594    list_del(&ewp->list);
595out_unlock:
596    spin_unlock(&info->lock);
597out:
598    return retval;
599}
600
601/*
602 * Returns waiting task that should be serviced first or NULL if none exists
603 */
604static struct ext_wait_queue *wq_get_first_waiter(
605        struct mqueue_inode_info *info, int sr)
606{
607    struct list_head *ptr;
608
609    ptr = info->e_wait_q[sr].list.prev;
610    if (ptr == &info->e_wait_q[sr].list)
611        return NULL;
612    return list_entry(ptr, struct ext_wait_queue, list);
613}
614
615
616static inline void set_cookie(struct sk_buff *skb, char code)
617{
618    ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
619}
620
621/*
622 * The next function is only to split too long sys_mq_timedsend
623 */
624static void __do_notify(struct mqueue_inode_info *info)
625{
626    /* notification
627     * invoked when there is registered process and there isn't process
628     * waiting synchronously for message AND state of queue changed from
629     * empty to not empty. Here we are sure that no one is waiting
630     * synchronously. */
631    if (info->notify_owner &&
632        info->attr.mq_curmsgs == 1) {
633        struct siginfo sig_i;
634        switch (info->notify.sigev_notify) {
635        case SIGEV_NONE:
636            break;
637        case SIGEV_SIGNAL:
638            /* sends signal */
639
640            sig_i.si_signo = info->notify.sigev_signo;
641            sig_i.si_errno = 0;
642            sig_i.si_code = SI_MESGQ;
643            sig_i.si_value = info->notify.sigev_value;
644            /* map current pid/uid into info->owner's namespaces */
645            rcu_read_lock();
646            sig_i.si_pid = task_tgid_nr_ns(current,
647                        ns_of_pid(info->notify_owner));
648            sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
649            rcu_read_unlock();
650
651            kill_pid_info(info->notify.sigev_signo,
652                      &sig_i, info->notify_owner);
653            break;
654        case SIGEV_THREAD:
655            set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
656            netlink_sendskb(info->notify_sock, info->notify_cookie);
657            break;
658        }
659        /* after notification unregisters process */
660        put_pid(info->notify_owner);
661        put_user_ns(info->notify_user_ns);
662        info->notify_owner = NULL;
663        info->notify_user_ns = NULL;
664    }
665    wake_up(&info->wait_q);
666}
667
668static int prepare_timeout(const struct timespec __user *u_abs_timeout,
669               ktime_t *expires, struct timespec *ts)
670{
671    if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
672        return -EFAULT;
673    if (!timespec_valid(ts))
674        return -EINVAL;
675
676    *expires = timespec_to_ktime(*ts);
677    return 0;
678}
679
680static void remove_notification(struct mqueue_inode_info *info)
681{
682    if (info->notify_owner != NULL &&
683        info->notify.sigev_notify == SIGEV_THREAD) {
684        set_cookie(info->notify_cookie, NOTIFY_REMOVED);
685        netlink_sendskb(info->notify_sock, info->notify_cookie);
686    }
687    put_pid(info->notify_owner);
688    put_user_ns(info->notify_user_ns);
689    info->notify_owner = NULL;
690    info->notify_user_ns = NULL;
691}
692
693static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
694{
695    int mq_treesize;
696    unsigned long total_size;
697
698    if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
699        return -EINVAL;
700    if (capable(CAP_SYS_RESOURCE)) {
701        if (attr->mq_maxmsg > HARD_MSGMAX ||
702            attr->mq_msgsize > HARD_MSGSIZEMAX)
703            return -EINVAL;
704    } else {
705        if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
706                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
707            return -EINVAL;
708    }
709    /* check for overflow */
710    if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
711        return -EOVERFLOW;
712    mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
713        min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
714        sizeof(struct posix_msg_tree_node);
715    total_size = attr->mq_maxmsg * attr->mq_msgsize;
716    if (total_size + mq_treesize < total_size)
717        return -EOVERFLOW;
718    return 0;
719}
720
721/*
722 * Invoked when creating a new queue via sys_mq_open
723 */
724static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
725            struct path *path, int oflag, umode_t mode,
726            struct mq_attr *attr)
727{
728    const struct cred *cred = current_cred();
729    struct file *result;
730    int ret;
731
732    if (attr) {
733        ret = mq_attr_ok(ipc_ns, attr);
734        if (ret)
735            return ERR_PTR(ret);
736        /* store for use during create */
737        path->dentry->d_fsdata = attr;
738    } else {
739        struct mq_attr def_attr;
740
741        def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
742                     ipc_ns->mq_msg_default);
743        def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
744                      ipc_ns->mq_msgsize_default);
745        ret = mq_attr_ok(ipc_ns, &def_attr);
746        if (ret)
747            return ERR_PTR(ret);
748    }
749
750    mode &= ~current_umask();
751    ret = mnt_want_write(path->mnt);
752    if (ret)
753        return ERR_PTR(ret);
754    ret = vfs_create(dir, path->dentry, mode, true);
755    path->dentry->d_fsdata = NULL;
756    if (!ret)
757        result = dentry_open(path, oflag, cred);
758    else
759        result = ERR_PTR(ret);
760    /*
761     * dentry_open() took a persistent mnt_want_write(),
762     * so we can now drop this one.
763     */
764    mnt_drop_write(path->mnt);
765    return result;
766}
767
768/* Opens existing queue */
769static struct file *do_open(struct path *path, int oflag)
770{
771    static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
772                          MAY_READ | MAY_WRITE };
773    int acc;
774    if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
775        return ERR_PTR(-EINVAL);
776    acc = oflag2acc[oflag & O_ACCMODE];
777    if (inode_permission(path->dentry->d_inode, acc))
778        return ERR_PTR(-EACCES);
779    return dentry_open(path, oflag, current_cred());
780}
781
782SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
783        struct mq_attr __user *, u_attr)
784{
785    struct path path;
786    struct file *filp;
787    char *name;
788    struct mq_attr attr;
789    int fd, error;
790    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
791    struct dentry *root = ipc_ns->mq_mnt->mnt_root;
792
793    if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
794        return -EFAULT;
795
796    audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
797
798    if (IS_ERR(name = getname(u_name)))
799        return PTR_ERR(name);
800
801    fd = get_unused_fd_flags(O_CLOEXEC);
802    if (fd < 0)
803        goto out_putname;
804
805    error = 0;
806    mutex_lock(&root->d_inode->i_mutex);
807    path.dentry = lookup_one_len(name, root, strlen(name));
808    if (IS_ERR(path.dentry)) {
809        error = PTR_ERR(path.dentry);
810        goto out_putfd;
811    }
812    path.mnt = mntget(ipc_ns->mq_mnt);
813
814    if (oflag & O_CREAT) {
815        if (path.dentry->d_inode) { /* entry already exists */
816            audit_inode(name, path.dentry);
817            if (oflag & O_EXCL) {
818                error = -EEXIST;
819                goto out;
820            }
821            filp = do_open(&path, oflag);
822        } else {
823            filp = do_create(ipc_ns, root->d_inode,
824                        &path, oflag, mode,
825                        u_attr ? &attr : NULL);
826        }
827    } else {
828        if (!path.dentry->d_inode) {
829            error = -ENOENT;
830            goto out;
831        }
832        audit_inode(name, path.dentry);
833        filp = do_open(&path, oflag);
834    }
835
836    if (!IS_ERR(filp))
837        fd_install(fd, filp);
838    else
839        error = PTR_ERR(filp);
840out:
841    path_put(&path);
842out_putfd:
843    if (error) {
844        put_unused_fd(fd);
845        fd = error;
846    }
847    mutex_unlock(&root->d_inode->i_mutex);
848out_putname:
849    putname(name);
850    return fd;
851}
852
853SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
854{
855    int err;
856    char *name;
857    struct dentry *dentry;
858    struct inode *inode = NULL;
859    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
860
861    name = getname(u_name);
862    if (IS_ERR(name))
863        return PTR_ERR(name);
864
865    mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
866            I_MUTEX_PARENT);
867    dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
868    if (IS_ERR(dentry)) {
869        err = PTR_ERR(dentry);
870        goto out_unlock;
871    }
872
873    if (!dentry->d_inode) {
874        err = -ENOENT;
875        goto out_err;
876    }
877
878    inode = dentry->d_inode;
879    if (inode)
880        ihold(inode);
881    err = mnt_want_write(ipc_ns->mq_mnt);
882    if (err)
883        goto out_err;
884    err = vfs_unlink(dentry->d_parent->d_inode, dentry);
885    mnt_drop_write(ipc_ns->mq_mnt);
886out_err:
887    dput(dentry);
888
889out_unlock:
890    mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
891    putname(name);
892    if (inode)
893        iput(inode);
894
895    return err;
896}
897
898/* Pipelined send and receive functions.
899 *
900 * If a receiver finds no waiting message, then it registers itself in the
901 * list of waiting receivers. A sender checks that list before adding the new
902 * message into the message array. If there is a waiting receiver, then it
903 * bypasses the message array and directly hands the message over to the
904 * receiver.
905 * The receiver accepts the message and returns without grabbing the queue
906 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
907 * are necessary. The same algorithm is used for sysv semaphores, see
908 * ipc/sem.c for more details.
909 *
910 * The same algorithm is used for senders.
911 */
912
913/* pipelined_send() - send a message directly to the task waiting in
914 * sys_mq_timedreceive() (without inserting message into a queue).
915 */
916static inline void pipelined_send(struct mqueue_inode_info *info,
917                  struct msg_msg *message,
918                  struct ext_wait_queue *receiver)
919{
920    receiver->msg = message;
921    list_del(&receiver->list);
922    receiver->state = STATE_PENDING;
923    wake_up_process(receiver->task);
924    smp_wmb();
925    receiver->state = STATE_READY;
926}
927
928/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
929 * gets its message and put to the queue (we have one free place for sure). */
930static inline void pipelined_receive(struct mqueue_inode_info *info)
931{
932    struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
933
934    if (!sender) {
935        /* for poll */
936        wake_up_interruptible(&info->wait_q);
937        return;
938    }
939    if (msg_insert(sender->msg, info))
940        return;
941    list_del(&sender->list);
942    sender->state = STATE_PENDING;
943    wake_up_process(sender->task);
944    smp_wmb();
945    sender->state = STATE_READY;
946}
947
948SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
949        size_t, msg_len, unsigned int, msg_prio,
950        const struct timespec __user *, u_abs_timeout)
951{
952    struct file *filp;
953    struct inode *inode;
954    struct ext_wait_queue wait;
955    struct ext_wait_queue *receiver;
956    struct msg_msg *msg_ptr;
957    struct mqueue_inode_info *info;
958    ktime_t expires, *timeout = NULL;
959    struct timespec ts;
960    struct posix_msg_tree_node *new_leaf = NULL;
961    int ret = 0;
962
963    if (u_abs_timeout) {
964        int res = prepare_timeout(u_abs_timeout, &expires, &ts);
965        if (res)
966            return res;
967        timeout = &expires;
968    }
969
970    if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
971        return -EINVAL;
972
973    audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
974
975    filp = fget(mqdes);
976    if (unlikely(!filp)) {
977        ret = -EBADF;
978        goto out;
979    }
980
981    inode = filp->f_path.dentry->d_inode;
982    if (unlikely(filp->f_op != &mqueue_file_operations)) {
983        ret = -EBADF;
984        goto out_fput;
985    }
986    info = MQUEUE_I(inode);
987    audit_inode(NULL, filp->f_path.dentry);
988
989    if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
990        ret = -EBADF;
991        goto out_fput;
992    }
993
994    if (unlikely(msg_len > info->attr.mq_msgsize)) {
995        ret = -EMSGSIZE;
996        goto out_fput;
997    }
998
999    /* First try to allocate memory, before doing anything with
1000     * existing queues. */
1001    msg_ptr = load_msg(u_msg_ptr, msg_len);
1002    if (IS_ERR(msg_ptr)) {
1003        ret = PTR_ERR(msg_ptr);
1004        goto out_fput;
1005    }
1006    msg_ptr->m_ts = msg_len;
1007    msg_ptr->m_type = msg_prio;
1008
1009    /*
1010     * msg_insert really wants us to have a valid, spare node struct so
1011     * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1012     * fall back to that if necessary.
1013     */
1014    if (!info->node_cache)
1015        new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1016
1017    spin_lock(&info->lock);
1018
1019    if (!info->node_cache && new_leaf) {
1020        /* Save our speculative allocation into the cache */
1021        rb_init_node(&new_leaf->rb_node);
1022        INIT_LIST_HEAD(&new_leaf->msg_list);
1023        info->node_cache = new_leaf;
1024        info->qsize += sizeof(*new_leaf);
1025        new_leaf = NULL;
1026    } else {
1027        kfree(new_leaf);
1028    }
1029
1030    if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1031        if (filp->f_flags & O_NONBLOCK) {
1032            ret = -EAGAIN;
1033        } else {
1034            wait.task = current;
1035            wait.msg = (void *) msg_ptr;
1036            wait.state = STATE_NONE;
1037            ret = wq_sleep(info, SEND, timeout, &wait);
1038            /*
1039             * wq_sleep must be called with info->lock held, and
1040             * returns with the lock released
1041             */
1042            goto out_free;
1043        }
1044    } else {
1045        receiver = wq_get_first_waiter(info, RECV);
1046        if (receiver) {
1047            pipelined_send(info, msg_ptr, receiver);
1048        } else {
1049            /* adds message to the queue */
1050            ret = msg_insert(msg_ptr, info);
1051            if (ret)
1052                goto out_unlock;
1053            __do_notify(info);
1054        }
1055        inode->i_atime = inode->i_mtime = inode->i_ctime =
1056                CURRENT_TIME;
1057    }
1058out_unlock:
1059    spin_unlock(&info->lock);
1060out_free:
1061    if (ret)
1062        free_msg(msg_ptr);
1063out_fput:
1064    fput(filp);
1065out:
1066    return ret;
1067}
1068
1069SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1070        size_t, msg_len, unsigned int __user *, u_msg_prio,
1071        const struct timespec __user *, u_abs_timeout)
1072{
1073    ssize_t ret;
1074    struct msg_msg *msg_ptr;
1075    struct file *filp;
1076    struct inode *inode;
1077    struct mqueue_inode_info *info;
1078    struct ext_wait_queue wait;
1079    ktime_t expires, *timeout = NULL;
1080    struct timespec ts;
1081    struct posix_msg_tree_node *new_leaf = NULL;
1082
1083    if (u_abs_timeout) {
1084        int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1085        if (res)
1086            return res;
1087        timeout = &expires;
1088    }
1089
1090    audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1091
1092    filp = fget(mqdes);
1093    if (unlikely(!filp)) {
1094        ret = -EBADF;
1095        goto out;
1096    }
1097
1098    inode = filp->f_path.dentry->d_inode;
1099    if (unlikely(filp->f_op != &mqueue_file_operations)) {
1100        ret = -EBADF;
1101        goto out_fput;
1102    }
1103    info = MQUEUE_I(inode);
1104    audit_inode(NULL, filp->f_path.dentry);
1105
1106    if (unlikely(!(filp->f_mode & FMODE_READ))) {
1107        ret = -EBADF;
1108        goto out_fput;
1109    }
1110
1111    /* checks if buffer is big enough */
1112    if (unlikely(msg_len < info->attr.mq_msgsize)) {
1113        ret = -EMSGSIZE;
1114        goto out_fput;
1115    }
1116
1117    /*
1118     * msg_insert really wants us to have a valid, spare node struct so
1119     * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1120     * fall back to that if necessary.
1121     */
1122    if (!info->node_cache)
1123        new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1124
1125    spin_lock(&info->lock);
1126
1127    if (!info->node_cache && new_leaf) {
1128        /* Save our speculative allocation into the cache */
1129        rb_init_node(&new_leaf->rb_node);
1130        INIT_LIST_HEAD(&new_leaf->msg_list);
1131        info->node_cache = new_leaf;
1132        info->qsize += sizeof(*new_leaf);
1133    } else {
1134        kfree(new_leaf);
1135    }
1136
1137    if (info->attr.mq_curmsgs == 0) {
1138        if (filp->f_flags & O_NONBLOCK) {
1139            spin_unlock(&info->lock);
1140            ret = -EAGAIN;
1141        } else {
1142            wait.task = current;
1143            wait.state = STATE_NONE;
1144            ret = wq_sleep(info, RECV, timeout, &wait);
1145            msg_ptr = wait.msg;
1146        }
1147    } else {
1148        msg_ptr = msg_get(info);
1149
1150        inode->i_atime = inode->i_mtime = inode->i_ctime =
1151                CURRENT_TIME;
1152
1153        /* There is now free space in queue. */
1154        pipelined_receive(info);
1155        spin_unlock(&info->lock);
1156        ret = 0;
1157    }
1158    if (ret == 0) {
1159        ret = msg_ptr->m_ts;
1160
1161        if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1162            store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1163            ret = -EFAULT;
1164        }
1165        free_msg(msg_ptr);
1166    }
1167out_fput:
1168    fput(filp);
1169out:
1170    return ret;
1171}
1172
1173/*
1174 * Notes: the case when user wants us to deregister (with NULL as pointer)
1175 * and he isn't currently owner of notification, will be silently discarded.
1176 * It isn't explicitly defined in the POSIX.
1177 */
1178SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1179        const struct sigevent __user *, u_notification)
1180{
1181    int ret;
1182    struct file *filp;
1183    struct sock *sock;
1184    struct inode *inode;
1185    struct sigevent notification;
1186    struct mqueue_inode_info *info;
1187    struct sk_buff *nc;
1188
1189    if (u_notification) {
1190        if (copy_from_user(&notification, u_notification,
1191                    sizeof(struct sigevent)))
1192            return -EFAULT;
1193    }
1194
1195    audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1196
1197    nc = NULL;
1198    sock = NULL;
1199    if (u_notification != NULL) {
1200        if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1201                 notification.sigev_notify != SIGEV_SIGNAL &&
1202                 notification.sigev_notify != SIGEV_THREAD))
1203            return -EINVAL;
1204        if (notification.sigev_notify == SIGEV_SIGNAL &&
1205            !valid_signal(notification.sigev_signo)) {
1206            return -EINVAL;
1207        }
1208        if (notification.sigev_notify == SIGEV_THREAD) {
1209            long timeo;
1210
1211            /* create the notify skb */
1212            nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1213            if (!nc) {
1214                ret = -ENOMEM;
1215                goto out;
1216            }
1217            if (copy_from_user(nc->data,
1218                    notification.sigev_value.sival_ptr,
1219                    NOTIFY_COOKIE_LEN)) {
1220                ret = -EFAULT;
1221                goto out;
1222            }
1223
1224            /* TODO: add a header? */
1225            skb_put(nc, NOTIFY_COOKIE_LEN);
1226            /* and attach it to the socket */
1227retry:
1228            filp = fget(notification.sigev_signo);
1229            if (!filp) {
1230                ret = -EBADF;
1231                goto out;
1232            }
1233            sock = netlink_getsockbyfilp(filp);
1234            fput(filp);
1235            if (IS_ERR(sock)) {
1236                ret = PTR_ERR(sock);
1237                sock = NULL;
1238                goto out;
1239            }
1240
1241            timeo = MAX_SCHEDULE_TIMEOUT;
1242            ret = netlink_attachskb(sock, nc, &timeo, NULL);
1243            if (ret == 1)
1244                goto retry;
1245            if (ret) {
1246                sock = NULL;
1247                nc = NULL;
1248                goto out;
1249            }
1250        }
1251    }
1252
1253    filp = fget(mqdes);
1254    if (!filp) {
1255        ret = -EBADF;
1256        goto out;
1257    }
1258
1259    inode = filp->f_path.dentry->d_inode;
1260    if (unlikely(filp->f_op != &mqueue_file_operations)) {
1261        ret = -EBADF;
1262        goto out_fput;
1263    }
1264    info = MQUEUE_I(inode);
1265
1266    ret = 0;
1267    spin_lock(&info->lock);
1268    if (u_notification == NULL) {
1269        if (info->notify_owner == task_tgid(current)) {
1270            remove_notification(info);
1271            inode->i_atime = inode->i_ctime = CURRENT_TIME;
1272        }
1273    } else if (info->notify_owner != NULL) {
1274        ret = -EBUSY;
1275    } else {
1276        switch (notification.sigev_notify) {
1277        case SIGEV_NONE:
1278            info->notify.sigev_notify = SIGEV_NONE;
1279            break;
1280        case SIGEV_THREAD:
1281            info->notify_sock = sock;
1282            info->notify_cookie = nc;
1283            sock = NULL;
1284            nc = NULL;
1285            info->notify.sigev_notify = SIGEV_THREAD;
1286            break;
1287        case SIGEV_SIGNAL:
1288            info->notify.sigev_signo = notification.sigev_signo;
1289            info->notify.sigev_value = notification.sigev_value;
1290            info->notify.sigev_notify = SIGEV_SIGNAL;
1291            break;
1292        }
1293
1294        info->notify_owner = get_pid(task_tgid(current));
1295        info->notify_user_ns = get_user_ns(current_user_ns());
1296        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1297    }
1298    spin_unlock(&info->lock);
1299out_fput:
1300    fput(filp);
1301out:
1302    if (sock) {
1303        netlink_detachskb(sock, nc);
1304    } else if (nc) {
1305        dev_kfree_skb(nc);
1306    }
1307    return ret;
1308}
1309
1310SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1311        const struct mq_attr __user *, u_mqstat,
1312        struct mq_attr __user *, u_omqstat)
1313{
1314    int ret;
1315    struct mq_attr mqstat, omqstat;
1316    struct file *filp;
1317    struct inode *inode;
1318    struct mqueue_inode_info *info;
1319
1320    if (u_mqstat != NULL) {
1321        if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1322            return -EFAULT;
1323        if (mqstat.mq_flags & (~O_NONBLOCK))
1324            return -EINVAL;
1325    }
1326
1327    filp = fget(mqdes);
1328    if (!filp) {
1329        ret = -EBADF;
1330        goto out;
1331    }
1332
1333    inode = filp->f_path.dentry->d_inode;
1334    if (unlikely(filp->f_op != &mqueue_file_operations)) {
1335        ret = -EBADF;
1336        goto out_fput;
1337    }
1338    info = MQUEUE_I(inode);
1339
1340    spin_lock(&info->lock);
1341
1342    omqstat = info->attr;
1343    omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1344    if (u_mqstat) {
1345        audit_mq_getsetattr(mqdes, &mqstat);
1346        spin_lock(&filp->f_lock);
1347        if (mqstat.mq_flags & O_NONBLOCK)
1348            filp->f_flags |= O_NONBLOCK;
1349        else
1350            filp->f_flags &= ~O_NONBLOCK;
1351        spin_unlock(&filp->f_lock);
1352
1353        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1354    }
1355
1356    spin_unlock(&info->lock);
1357
1358    ret = 0;
1359    if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1360                        sizeof(struct mq_attr)))
1361        ret = -EFAULT;
1362
1363out_fput:
1364    fput(filp);
1365out:
1366    return ret;
1367}
1368
1369static const struct inode_operations mqueue_dir_inode_operations = {
1370    .lookup = simple_lookup,
1371    .create = mqueue_create,
1372    .unlink = mqueue_unlink,
1373};
1374
1375static const struct file_operations mqueue_file_operations = {
1376    .flush = mqueue_flush_file,
1377    .poll = mqueue_poll_file,
1378    .read = mqueue_read_file,
1379    .llseek = default_llseek,
1380};
1381
1382static const struct super_operations mqueue_super_ops = {
1383    .alloc_inode = mqueue_alloc_inode,
1384    .destroy_inode = mqueue_destroy_inode,
1385    .evict_inode = mqueue_evict_inode,
1386    .statfs = simple_statfs,
1387};
1388
1389static struct file_system_type mqueue_fs_type = {
1390    .name = "mqueue",
1391    .mount = mqueue_mount,
1392    .kill_sb = kill_litter_super,
1393};
1394
1395int mq_init_ns(struct ipc_namespace *ns)
1396{
1397    ns->mq_queues_count = 0;
1398    ns->mq_queues_max = DFLT_QUEUESMAX;
1399    ns->mq_msg_max = DFLT_MSGMAX;
1400    ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1401    ns->mq_msg_default = DFLT_MSG;
1402    ns->mq_msgsize_default = DFLT_MSGSIZE;
1403
1404    ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1405    if (IS_ERR(ns->mq_mnt)) {
1406        int err = PTR_ERR(ns->mq_mnt);
1407        ns->mq_mnt = NULL;
1408        return err;
1409    }
1410    return 0;
1411}
1412
1413void mq_clear_sbinfo(struct ipc_namespace *ns)
1414{
1415    ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1416}
1417
1418void mq_put_mnt(struct ipc_namespace *ns)
1419{
1420    kern_unmount(ns->mq_mnt);
1421}
1422
1423static int __init init_mqueue_fs(void)
1424{
1425    int error;
1426
1427    mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1428                sizeof(struct mqueue_inode_info), 0,
1429                SLAB_HWCACHE_ALIGN, init_once);
1430    if (mqueue_inode_cachep == NULL)
1431        return -ENOMEM;
1432
1433    /* ignore failures - they are not fatal */
1434    mq_sysctl_table = mq_register_sysctl_table();
1435
1436    error = register_filesystem(&mqueue_fs_type);
1437    if (error)
1438        goto out_sysctl;
1439
1440    spin_lock_init(&mq_lock);
1441
1442    error = mq_init_ns(&init_ipc_ns);
1443    if (error)
1444        goto out_filesystem;
1445
1446    return 0;
1447
1448out_filesystem:
1449    unregister_filesystem(&mqueue_fs_type);
1450out_sysctl:
1451    if (mq_sysctl_table)
1452        unregister_sysctl_table(mq_sysctl_table);
1453    kmem_cache_destroy(mqueue_inode_cachep);
1454    return error;
1455}
1456
1457__initcall(init_mqueue_fs);
1458

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