Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1252 insertions, 0 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
new file mode 100644
index 000000000000..cb0cd3cf3b5a
--- /dev/null
+++ b/ipc/mqueue.c
@@ -0,0 +1,1252 @@
+/*
+ * POSIX message queues filesystem for Linux.
+ *
+ * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
+ *                          Michal Wronski          (wrona@mat.uni.torun.pl)
+ *
+ * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
+ * Lockless receive & send, fd based notify:
+ *                          Manfred Spraul          (manfred@colorfullife.com)
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/sysctl.h>
+#include <linux/poll.h>
+#include <linux/mqueue.h>
+#include <linux/msg.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/syscalls.h>
+#include <net/sock.h>
+#include "util.h"
+
+#define MQUEUE_MAGIC    0x19800202
+#define DIRENT_SIZE     20
+#define FILENT_SIZE     80
+
+#define SEND            0
+#define RECV            1
+
+#define STATE_NONE      0
+#define STATE_PENDING   1
+#define STATE_READY     2
+
+/* used by sysctl */
+#define FS_MQUEUE       1
+#define CTL_QUEUESMAX   2
+#define CTL_MSGMAX      3
+#define CTL_MSGSIZEMAX  4
+
+/* default values */
+#define DFLT_QUEUESMAX  256     /* max number of message queues */
+#define DFLT_MSGMAX     10      /* max number of messages in each queue */
+#define HARD_MSGMAX     (131072/sizeof(void*))
+#define DFLT_MSGSIZEMAX 8192    /* max message size */
+
+#define NOTIFY_COOKIE_LEN       32
+
+struct ext_wait_queue {         /* queue of sleeping tasks */
+        struct task_struct *task;
+        struct list_head list;
+        struct msg_msg *msg;    /* ptr of loaded message */
+        int state;              /* one of STATE_* values */
+};
+
+struct mqueue_inode_info {
+        spinlock_t lock;
+        struct inode vfs_inode;
+        wait_queue_head_t wait_q;
+
+        struct msg_msg **messages;
+        struct mq_attr attr;
+
+        struct sigevent notify;
+        pid_t notify_owner;
+        struct user_struct *user;       /* user who created, for accouting */
+        struct sock *notify_sock;
+        struct sk_buff *notify_cookie;
+
+        /* for tasks waiting for free space and messages, respectively */
+        struct ext_wait_queue e_wait_q[2];
+
+        unsigned long qsize; /* size of queue in memory (sum of all msgs) */
+};
+
+static struct inode_operations mqueue_dir_inode_operations;
+static struct file_operations mqueue_file_operations;
+static struct super_operations mqueue_super_ops;
+static void remove_notification(struct mqueue_inode_info *info);
+
+static spinlock_t mq_lock;
+static kmem_cache_t *mqueue_inode_cachep;
+static struct vfsmount *mqueue_mnt;
+
+static unsigned int queues_count;
+static unsigned int queues_max  = DFLT_QUEUESMAX;
+static unsigned int msg_max     = DFLT_MSGMAX;
+static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
+
+static struct ctl_table_header * mq_sysctl_table;
+
+static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
+{
+        return container_of(inode, struct mqueue_inode_info, vfs_inode);
+}
+
+static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
+                                                        struct mq_attr *attr)
+{
+        struct inode *inode;
+
+        inode = new_inode(sb);
+        if (inode) {
+                inode->i_mode = mode;
+                inode->i_uid = current->fsuid;
+                inode->i_gid = current->fsgid;
+                inode->i_blksize = PAGE_CACHE_SIZE;
+                inode->i_blocks = 0;
+                inode->i_mtime = inode->i_ctime = inode->i_atime =
+                                CURRENT_TIME;
+
+                if (S_ISREG(mode)) {
+                        struct mqueue_inode_info *info;
+                        struct task_struct *p = current;
+                        struct user_struct *u = p->user;
+                        unsigned long mq_bytes, mq_msg_tblsz;
+
+                        inode->i_fop = &mqueue_file_operations;
+                        inode->i_size = FILENT_SIZE;
+                        /* mqueue specific info */
+                        info = MQUEUE_I(inode);
+                        spin_lock_init(&info->lock);
+                        init_waitqueue_head(&info->wait_q);
+                        INIT_LIST_HEAD(&info->e_wait_q[0].list);
+                        INIT_LIST_HEAD(&info->e_wait_q[1].list);
+                        info->messages = NULL;
+                        info->notify_owner = 0;
+                        info->qsize = 0;
+                        info->user = NULL;      /* set when all is ok */
+                        memset(&info->attr, 0, sizeof(info->attr));
+                        info->attr.mq_maxmsg = DFLT_MSGMAX;
+                        info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
+                        if (attr) {
+                                info->attr.mq_maxmsg = attr->mq_maxmsg;
+                                info->attr.mq_msgsize = attr->mq_msgsize;
+                        }
+                        mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
+                        mq_bytes = (mq_msg_tblsz +
+                                (info->attr.mq_maxmsg * info->attr.mq_msgsize));
+
+                        spin_lock(&mq_lock);
+                        if (u->mq_bytes + mq_bytes < u->mq_bytes ||
+                            u->mq_bytes + mq_bytes >
+                            p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
+                                spin_unlock(&mq_lock);
+                                goto out_inode;
+                        }
+                        u->mq_bytes += mq_bytes;
+                        spin_unlock(&mq_lock);
+
+                        info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
+                        if (!info->messages) {
+                                spin_lock(&mq_lock);
+                                u->mq_bytes -= mq_bytes;
+                                spin_unlock(&mq_lock);
+                                goto out_inode;
+                        }
+                        /* all is ok */
+                        info->user = get_uid(u);
+                } else if (S_ISDIR(mode)) {
+                        inode->i_nlink++;
+                        /* Some things misbehave if size == 0 on a directory */
+                        inode->i_size = 2 * DIRENT_SIZE;
+                        inode->i_op = &mqueue_dir_inode_operations;
+                        inode->i_fop = &simple_dir_operations;
+                }
+        }
+        return inode;
+out_inode:
+        make_bad_inode(inode);
+        iput(inode);
+        return NULL;
+}
+
+static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
+{
+        struct inode *inode;
+
+        sb->s_blocksize = PAGE_CACHE_SIZE;
+        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+        sb->s_magic = MQUEUE_MAGIC;
+        sb->s_op = &mqueue_super_ops;
+
+        inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
+        if (!inode)
+                return -ENOMEM;
+
+        sb->s_root = d_alloc_root(inode);
+        if (!sb->s_root) {
+                iput(inode);
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
+                                         int flags, const char *dev_name,
+                                         void *data)
+{
+        return get_sb_single(fs_type, flags, data, mqueue_fill_super);
+}
+
+static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
+{
+        struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
+
+        if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
+                SLAB_CTOR_CONSTRUCTOR)
+                inode_init_once(&p->vfs_inode);
+}
+
+static struct inode *mqueue_alloc_inode(struct super_block *sb)
+{
+        struct mqueue_inode_info *ei;
+
+        ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
+        if (!ei)
+                return NULL;
+        return &ei->vfs_inode;
+}
+
+static void mqueue_destroy_inode(struct inode *inode)
+{
+        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
+}
+
+static void mqueue_delete_inode(struct inode *inode)
+{
+        struct mqueue_inode_info *info;
+        struct user_struct *user;
+        unsigned long mq_bytes;
+        int i;
+
+        if (S_ISDIR(inode->i_mode)) {
+                clear_inode(inode);
+                return;
+        }
+        info = MQUEUE_I(inode);
+        spin_lock(&info->lock);
+        for (i = 0; i < info->attr.mq_curmsgs; i++)
+                free_msg(info->messages[i]);
+        kfree(info->messages);
+        spin_unlock(&info->lock);
+
+        clear_inode(inode);
+
+        mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
+                   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
+        user = info->user;
+        if (user) {
+                spin_lock(&mq_lock);
+                user->mq_bytes -= mq_bytes;
+                queues_count--;
+                spin_unlock(&mq_lock);
+                free_uid(user);
+        }
+}
+
+static int mqueue_create(struct inode *dir, struct dentry *dentry,
+                                int mode, struct nameidata *nd)
+{
+        struct inode *inode;
+        struct mq_attr *attr = dentry->d_fsdata;
+        int error;
+
+        spin_lock(&mq_lock);
+        if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
+                error = -ENOSPC;
+                goto out_lock;
+        }
+        queues_count++;
+        spin_unlock(&mq_lock);
+
+        inode = mqueue_get_inode(dir->i_sb, mode, attr);
+        if (!inode) {
+                error = -ENOMEM;
+                spin_lock(&mq_lock);
+                queues_count--;
+                goto out_lock;
+        }
+
+        dir->i_size += DIRENT_SIZE;
+        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
+
+        d_instantiate(dentry, inode);
+        dget(dentry);
+        return 0;
+out_lock:
+        spin_unlock(&mq_lock);
+        return error;
+}
+
+static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
+{
+        struct inode *inode = dentry->d_inode;
+
+        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
+        dir->i_size -= DIRENT_SIZE;
+        inode->i_nlink--;
+        dput(dentry);
+        return 0;
+}
+
+/*
+*       This is routine for system read from queue file.
+*       To avoid mess with doing here some sort of mq_receive we allow
+*       to read only queue size & notification info (the only values
+*       that are interesting from user point of view and aren't accessible
+*       through std routines)
+*/
+static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
+                                size_t count, loff_t * off)
+{
+        struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
+        char buffer[FILENT_SIZE];
+        size_t slen;
+        loff_t o;
+
+        if (!count)
+                return 0;
+
+        spin_lock(&info->lock);
+        snprintf(buffer, sizeof(buffer),
+                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
+                        info->qsize,
+                        info->notify_owner ? info->notify.sigev_notify : 0,
+                        (info->notify_owner &&
+                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
+                                info->notify.sigev_signo : 0,
+                        info->notify_owner);
+        spin_unlock(&info->lock);
+        buffer[sizeof(buffer)-1] = '\0';
+        slen = strlen(buffer)+1;
+
+        o = *off;
+        if (o > slen)
+                return 0;
+
+        if (o + count > slen)
+                count = slen - o;
+
+        if (copy_to_user(u_data, buffer + o, count))
+                return -EFAULT;
+
+        *off = o + count;
+        filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
+        return count;
+}
+
+static int mqueue_flush_file(struct file *filp)
+{
+        struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
+
+        spin_lock(&info->lock);
+        if (current->tgid == info->notify_owner)
+                remove_notification(info);
+
+        spin_unlock(&info->lock);
+        return 0;
+}
+
+static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
+{
+        struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
+        int retval = 0;
+
+        poll_wait(filp, &info->wait_q, poll_tab);
+
+        spin_lock(&info->lock);
+        if (info->attr.mq_curmsgs)
+                retval = POLLIN | POLLRDNORM;
+
+        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
+                retval |= POLLOUT | POLLWRNORM;
+        spin_unlock(&info->lock);
+
+        return retval;
+}
+
+/* Adds current to info->e_wait_q[sr] before element with smaller prio */
+static void wq_add(struct mqueue_inode_info *info, int sr,
+                        struct ext_wait_queue *ewp)
+{
+        struct ext_wait_queue *walk;
+
+        ewp->task = current;
+
+        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
+                if (walk->task->static_prio <= current->static_prio) {
+                        list_add_tail(&ewp->list, &walk->list);
+                        return;
+                }
+        }
+        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
+}
+
+/*
+ * Puts current task to sleep. Caller must hold queue lock. After return
+ * lock isn't held.
+ * sr: SEND or RECV
+ */
+static int wq_sleep(struct mqueue_inode_info *info, int sr,
+                        long timeout, struct ext_wait_queue *ewp)
+{
+        int retval;
+        signed long time;
+
+        wq_add(info, sr, ewp);
+
+        for (;;) {
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                spin_unlock(&info->lock);
+                time = schedule_timeout(timeout);
+
+                while (ewp->state == STATE_PENDING)
+                        cpu_relax();
+
+                if (ewp->state == STATE_READY) {
+                        retval = 0;
+                        goto out;
+                }
+                spin_lock(&info->lock);
+                if (ewp->state == STATE_READY) {
+                        retval = 0;
+                        goto out_unlock;
+                }
+                if (signal_pending(current)) {
+                        retval = -ERESTARTSYS;
+                        break;
+                }
+                if (time == 0) {
+                        retval = -ETIMEDOUT;
+                        break;
+                }
+        }
+        list_del(&ewp->list);
+out_unlock:
+        spin_unlock(&info->lock);
+out:
+        return retval;
+}
+
+/*
+ * Returns waiting task that should be serviced first or NULL if none exists
+ */
+static struct ext_wait_queue *wq_get_first_waiter(
+                struct mqueue_inode_info *info, int sr)
+{
+        struct list_head *ptr;
+
+        ptr = info->e_wait_q[sr].list.prev;
+        if (ptr == &info->e_wait_q[sr].list)
+                return NULL;
+        return list_entry(ptr, struct ext_wait_queue, list);
+}
+
+/* Auxiliary functions to manipulate messages' list */
+static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
+{
+        int k;
+
+        k = info->attr.mq_curmsgs - 1;
+        while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
+                info->messages[k + 1] = info->messages[k];
+                k--;
+        }
+        info->attr.mq_curmsgs++;
+        info->qsize += ptr->m_ts;
+        info->messages[k + 1] = ptr;
+}
+
+static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
+{
+        info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
+        return info->messages[info->attr.mq_curmsgs];
+}
+
+static inline void set_cookie(struct sk_buff *skb, char code)
+{
+        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
+}
+
+/*
+ * The next function is only to split too long sys_mq_timedsend
+ */
+static void __do_notify(struct mqueue_inode_info *info)
+{
+        /* notification
+         * invoked when there is registered process and there isn't process
+         * waiting synchronously for message AND state of queue changed from
+         * empty to not empty. Here we are sure that no one is waiting
+         * synchronously. */
+        if (info->notify_owner &&
+            info->attr.mq_curmsgs == 1) {
+                struct siginfo sig_i;
+                switch (info->notify.sigev_notify) {
+                case SIGEV_NONE:
+                        break;
+                case SIGEV_SIGNAL:
+                        /* sends signal */
+
+                        sig_i.si_signo = info->notify.sigev_signo;
+                        sig_i.si_errno = 0;
+                        sig_i.si_code = SI_MESGQ;
+                        sig_i.si_value = info->notify.sigev_value;
+                        sig_i.si_pid = current->tgid;
+                        sig_i.si_uid = current->uid;
+
+                        kill_proc_info(info->notify.sigev_signo,
+                                       &sig_i, info->notify_owner);
+                        break;
+                case SIGEV_THREAD:
+                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
+                        netlink_sendskb(info->notify_sock,
+                                        info->notify_cookie, 0);
+                        break;
+                }
+                /* after notification unregisters process */
+                info->notify_owner = 0;
+        }
+        wake_up(&info->wait_q);
+}
+
+static long prepare_timeout(const struct timespec __user *u_arg)
+{
+        struct timespec ts, nowts;
+        long timeout;
+
+        if (u_arg) {
+                if (unlikely(copy_from_user(&ts, u_arg,
+                                        sizeof(struct timespec))))
+                        return -EFAULT;
+
+                if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
+                        || ts.tv_nsec >= NSEC_PER_SEC))
+                        return -EINVAL;
+                nowts = CURRENT_TIME;
+                /* first subtract as jiffies can't be too big */
+                ts.tv_sec -= nowts.tv_sec;
+                if (ts.tv_nsec < nowts.tv_nsec) {
+                        ts.tv_nsec += NSEC_PER_SEC;
+                        ts.tv_sec--;
+                }
+                ts.tv_nsec -= nowts.tv_nsec;
+                if (ts.tv_sec < 0)
+                        return 0;
+
+                timeout = timespec_to_jiffies(&ts) + 1;
+        } else
+                return MAX_SCHEDULE_TIMEOUT;
+
+        return timeout;
+}
+
+static void remove_notification(struct mqueue_inode_info *info)
+{
+        if (info->notify_owner != 0 &&
+            info->notify.sigev_notify == SIGEV_THREAD) {
+                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
+                netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
+        }
+        info->notify_owner = 0;
+}
+
+static int mq_attr_ok(struct mq_attr *attr)
+{
+        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
+                return 0;
+        if (capable(CAP_SYS_RESOURCE)) {
+                if (attr->mq_maxmsg > HARD_MSGMAX)
+                        return 0;
+        } else {
+                if (attr->mq_maxmsg > msg_max ||
+                                attr->mq_msgsize > msgsize_max)
+                        return 0;
+        }
+        /* check for overflow */
+        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
+                return 0;
+        if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
+            (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
+            (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
+                return 0;
+        return 1;
+}
+
+/*
+ * Invoked when creating a new queue via sys_mq_open
+ */
+static struct file *do_create(struct dentry *dir, struct dentry *dentry,
+                        int oflag, mode_t mode, struct mq_attr __user *u_attr)
+{
+        struct file *filp;
+        struct mq_attr attr;
+        int ret;
+
+        if (u_attr != NULL) {
+                if (copy_from_user(&attr, u_attr, sizeof(attr)))
+                        return ERR_PTR(-EFAULT);
+                if (!mq_attr_ok(&attr))
+                        return ERR_PTR(-EINVAL);
+                /* store for use during create */
+                dentry->d_fsdata = &attr;
+        }
+
+        ret = vfs_create(dir->d_inode, dentry, mode, NULL);
+        dentry->d_fsdata = NULL;
+        if (ret)
+                return ERR_PTR(ret);
+
+        filp = dentry_open(dentry, mqueue_mnt, oflag);
+        if (!IS_ERR(filp))
+                dget(dentry);
+
+        return filp;
+}
+
+/* Opens existing queue */
+static struct file *do_open(struct dentry *dentry, int oflag)
+{
+static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
+                                        MAY_READ | MAY_WRITE };
+        struct file *filp;
+
+        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
+                return ERR_PTR(-EINVAL);
+
+        if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
+                return ERR_PTR(-EACCES);
+
+        filp = dentry_open(dentry, mqueue_mnt, oflag);
+
+        if (!IS_ERR(filp))
+                dget(dentry);
+
+        return filp;
+}
+
+asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
+                                struct mq_attr __user *u_attr)
+{
+        struct dentry *dentry;
+        struct file *filp;
+        char *name;
+        int fd, error;
+
+        if (IS_ERR(name = getname(u_name)))
+                return PTR_ERR(name);
+
+        fd = get_unused_fd();
+        if (fd < 0)
+                goto out_putname;
+
+        down(&mqueue_mnt->mnt_root->d_inode->i_sem);
+        dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
+        if (IS_ERR(dentry)) {
+                error = PTR_ERR(dentry);
+                goto out_err;
+        }
+        mntget(mqueue_mnt);
+
+        if (oflag & O_CREAT) {
+                if (dentry->d_inode) {  /* entry already exists */
+                        filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
+                                        do_open(dentry, oflag);
+                } else {
+                        filp = do_create(mqueue_mnt->mnt_root, dentry,
+                                                oflag, mode, u_attr);
+                }
+        } else
+                filp = (dentry->d_inode) ? do_open(dentry, oflag) :
+                                        ERR_PTR(-ENOENT);
+
+        dput(dentry);
+
+        if (IS_ERR(filp)) {
+                error = PTR_ERR(filp);
+                goto out_putfd;
+        }
+
+        set_close_on_exec(fd, 1);
+        fd_install(fd, filp);
+        goto out_upsem;
+
+out_putfd:
+        mntput(mqueue_mnt);
+        put_unused_fd(fd);
+out_err:
+        fd = error;
+out_upsem:
+        up(&mqueue_mnt->mnt_root->d_inode->i_sem);
+out_putname:
+        putname(name);
+        return fd;
+}
+
+asmlinkage long sys_mq_unlink(const char __user *u_name)
+{
+        int err;
+        char *name;
+        struct dentry *dentry;
+        struct inode *inode = NULL;
+
+        name = getname(u_name);
+        if (IS_ERR(name))
+                return PTR_ERR(name);
+
+        down(&mqueue_mnt->mnt_root->d_inode->i_sem);
+        dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
+        if (IS_ERR(dentry)) {
+                err = PTR_ERR(dentry);
+                goto out_unlock;
+        }
+
+        if (!dentry->d_inode) {
+                err = -ENOENT;
+                goto out_err;
+        }
+
+        inode = dentry->d_inode;
+        if (inode)
+                atomic_inc(&inode->i_count);
+
+        err = vfs_unlink(dentry->d_parent->d_inode, dentry);
+out_err:
+        dput(dentry);
+
+out_unlock:
+        up(&mqueue_mnt->mnt_root->d_inode->i_sem);
+        putname(name);
+        if (inode)
+                iput(inode);
+
+        return err;
+}
+
+/* Pipelined send and receive functions.
+ *
+ * If a receiver finds no waiting message, then it registers itself in the
+ * list of waiting receivers. A sender checks that list before adding the new
+ * message into the message array. If there is a waiting receiver, then it
+ * bypasses the message array and directly hands the message over to the
+ * receiver.
+ * The receiver accepts the message and returns without grabbing the queue
+ * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
+ * are necessary. The same algorithm is used for sysv semaphores, see
+ * ipc/sem.c fore more details.
+ *
+ * The same algorithm is used for senders.
+ */
+
+/* pipelined_send() - send a message directly to the task waiting in
+ * sys_mq_timedreceive() (without inserting message into a queue).
+ */
+static inline void pipelined_send(struct mqueue_inode_info *info,
+                                  struct msg_msg *message,
+                                  struct ext_wait_queue *receiver)
+{
+        receiver->msg = message;
+        list_del(&receiver->list);
+        receiver->state = STATE_PENDING;
+        wake_up_process(receiver->task);
+        wmb();
+        receiver->state = STATE_READY;
+}
+
+/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
+ * gets its message and put to the queue (we have one free place for sure). */
+static inline void pipelined_receive(struct mqueue_inode_info *info)
+{
+        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
+
+        if (!sender) {
+                /* for poll */
+                wake_up_interruptible(&info->wait_q);
+                return;
+        }
+        msg_insert(sender->msg, info);
+        list_del(&sender->list);
+        sender->state = STATE_PENDING;
+        wake_up_process(sender->task);
+        wmb();
+        sender->state = STATE_READY;
+}
+
+asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
+        size_t msg_len, unsigned int msg_prio,
+        const struct timespec __user *u_abs_timeout)
+{
+        struct file *filp;
+        struct inode *inode;
+        struct ext_wait_queue wait;
+        struct ext_wait_queue *receiver;
+        struct msg_msg *msg_ptr;
+        struct mqueue_inode_info *info;
+        long timeout;
+        int ret;
+
+        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
+                return -EINVAL;
+
+        timeout = prepare_timeout(u_abs_timeout);
+
+        ret = -EBADF;
+        filp = fget(mqdes);
+        if (unlikely(!filp))
+                goto out;
+
+        inode = filp->f_dentry->d_inode;
+        if (unlikely(filp->f_op != &mqueue_file_operations))
+                goto out_fput;
+        info = MQUEUE_I(inode);
+
+        if (unlikely(!(filp->f_mode & FMODE_WRITE)))
+                goto out_fput;
+
+        if (unlikely(msg_len > info->attr.mq_msgsize)) {
+                ret = -EMSGSIZE;
+                goto out_fput;
+        }
+
+        /* First try to allocate memory, before doing anything with
+         * existing queues. */
+        msg_ptr = load_msg(u_msg_ptr, msg_len);
+        if (IS_ERR(msg_ptr)) {
+                ret = PTR_ERR(msg_ptr);
+                goto out_fput;
+        }
+        msg_ptr->m_ts = msg_len;
+        msg_ptr->m_type = msg_prio;
+
+        spin_lock(&info->lock);
+
+        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
+                if (filp->f_flags & O_NONBLOCK) {
+                        spin_unlock(&info->lock);
+                        ret = -EAGAIN;
+                } else if (unlikely(timeout < 0)) {
+                        spin_unlock(&info->lock);
+                        ret = timeout;
+                } else {
+                        wait.task = current;
+                        wait.msg = (void *) msg_ptr;
+                        wait.state = STATE_NONE;
+                        ret = wq_sleep(info, SEND, timeout, &wait);
+                }
+                if (ret < 0)
+                        free_msg(msg_ptr);
+        } else {
+                receiver = wq_get_first_waiter(info, RECV);
+                if (receiver) {
+                        pipelined_send(info, msg_ptr, receiver);
+                } else {
+                        /* adds message to the queue */
+                        msg_insert(msg_ptr, info);
+                        __do_notify(info);
+                }
+                inode->i_atime = inode->i_mtime = inode->i_ctime =
+                                CURRENT_TIME;
+                spin_unlock(&info->lock);
+                ret = 0;
+        }
+out_fput:
+        fput(filp);
+out:
+        return ret;
+}
+
+asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
+        size_t msg_len, unsigned int __user *u_msg_prio,
+        const struct timespec __user *u_abs_timeout)
+{
+        long timeout;
+        ssize_t ret;
+        struct msg_msg *msg_ptr;
+        struct file *filp;
+        struct inode *inode;
+        struct mqueue_inode_info *info;
+        struct ext_wait_queue wait;
+
+        timeout = prepare_timeout(u_abs_timeout);
+
+        ret = -EBADF;
+        filp = fget(mqdes);
+        if (unlikely(!filp))
+                goto out;
+
+        inode = filp->f_dentry->d_inode;
+        if (unlikely(filp->f_op != &mqueue_file_operations))
+                goto out_fput;
+        info = MQUEUE_I(inode);
+
+        if (unlikely(!(filp->f_mode & FMODE_READ)))
+                goto out_fput;
+
+        /* checks if buffer is big enough */
+        if (unlikely(msg_len < info->attr.mq_msgsize)) {
+                ret = -EMSGSIZE;
+                goto out_fput;
+        }
+
+        spin_lock(&info->lock);
+        if (info->attr.mq_curmsgs == 0) {
+                if (filp->f_flags & O_NONBLOCK) {
+                        spin_unlock(&info->lock);
+                        ret = -EAGAIN;
+                        msg_ptr = NULL;
+                } else if (unlikely(timeout < 0)) {
+                        spin_unlock(&info->lock);
+                        ret = timeout;
+                        msg_ptr = NULL;
+                } else {
+                        wait.task = current;
+                        wait.state = STATE_NONE;
+                        ret = wq_sleep(info, RECV, timeout, &wait);
+                        msg_ptr = wait.msg;
+                }
+        } else {
+                msg_ptr = msg_get(info);
+
+                inode->i_atime = inode->i_mtime = inode->i_ctime =
+                                CURRENT_TIME;
+
+                /* There is now free space in queue. */
+                pipelined_receive(info);
+                spin_unlock(&info->lock);
+                ret = 0;
+        }
+        if (ret == 0) {
+                ret = msg_ptr->m_ts;
+
+                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
+                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
+                        ret = -EFAULT;
+                }
+                free_msg(msg_ptr);
+        }
+out_fput:
+        fput(filp);
+out:
+        return ret;
+}
+
+/*
+ * Notes: the case when user wants us to deregister (with NULL as pointer)
+ * and he isn't currently owner of notification, will be silently discarded.
+ * It isn't explicitly defined in the POSIX.
+ */
+asmlinkage long sys_mq_notify(mqd_t mqdes,
+                                const struct sigevent __user *u_notification)
+{
+        int ret;
+        struct file *filp;
+        struct sock *sock;
+        struct inode *inode;
+        struct sigevent notification;
+        struct mqueue_inode_info *info;
+        struct sk_buff *nc;
+
+        nc = NULL;
+        sock = NULL;
+        if (u_notification != NULL) {
+                if (copy_from_user(&notification, u_notification,
+                                        sizeof(struct sigevent)))
+                        return -EFAULT;
+
+                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
+                             notification.sigev_notify != SIGEV_SIGNAL &&
+                             notification.sigev_notify != SIGEV_THREAD))
+                        return -EINVAL;
+                if (notification.sigev_notify == SIGEV_SIGNAL &&
+                        (notification.sigev_signo < 0 ||
+                         notification.sigev_signo > _NSIG)) {
+                        return -EINVAL;
+                }
+                if (notification.sigev_notify == SIGEV_THREAD) {
+                        /* create the notify skb */
+                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
+                        ret = -ENOMEM;
+                        if (!nc)
+                                goto out;
+                        ret = -EFAULT;
+                        if (copy_from_user(nc->data,
+                                        notification.sigev_value.sival_ptr,
+                                        NOTIFY_COOKIE_LEN)) {
+                                goto out;
+                        }
+
+                        /* TODO: add a header? */
+                        skb_put(nc, NOTIFY_COOKIE_LEN);
+                        /* and attach it to the socket */
+retry:
+                        filp = fget(notification.sigev_signo);
+                        ret = -EBADF;
+                        if (!filp)
+                                goto out;
+                        sock = netlink_getsockbyfilp(filp);
+                        fput(filp);
+                        if (IS_ERR(sock)) {
+                                ret = PTR_ERR(sock);
+                                sock = NULL;
+                                goto out;
+                        }
+
+                        ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
+                        if (ret == 1)
+                                goto retry;
+                        if (ret) {
+                                sock = NULL;
+                                nc = NULL;
+                                goto out;
+                        }
+                }
+        }
+
+        ret = -EBADF;
+        filp = fget(mqdes);
+        if (!filp)
+                goto out;
+
+        inode = filp->f_dentry->d_inode;
+        if (unlikely(filp->f_op != &mqueue_file_operations))
+                goto out_fput;
+        info = MQUEUE_I(inode);
+
+        ret = 0;
+        spin_lock(&info->lock);
+        if (u_notification == NULL) {
+                if (info->notify_owner == current->tgid) {
+                        remove_notification(info);
+                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
+                }
+        } else if (info->notify_owner != 0) {
+                ret = -EBUSY;
+        } else {
+                switch (notification.sigev_notify) {
+                case SIGEV_NONE:
+                        info->notify.sigev_notify = SIGEV_NONE;
+                        break;
+                case SIGEV_THREAD:
+                        info->notify_sock = sock;
+                        info->notify_cookie = nc;
+                        sock = NULL;
+                        nc = NULL;
+                        info->notify.sigev_notify = SIGEV_THREAD;
+                        break;
+                case SIGEV_SIGNAL:
+                        info->notify.sigev_signo = notification.sigev_signo;
+                        info->notify.sigev_value = notification.sigev_value;
+                        info->notify.sigev_notify = SIGEV_SIGNAL;
+                        break;
+                }
+                info->notify_owner = current->tgid;
+                inode->i_atime = inode->i_ctime = CURRENT_TIME;
+        }
+        spin_unlock(&info->lock);
+out_fput:
+        fput(filp);
+out:
+        if (sock) {
+                netlink_detachskb(sock, nc);
+        } else if (nc) {
+                dev_kfree_skb(nc);
+        }
+        return ret;
+}
+
+asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
+                        const struct mq_attr __user *u_mqstat,
+                        struct mq_attr __user *u_omqstat)
+{
+        int ret;
+        struct mq_attr mqstat, omqstat;
+        struct file *filp;
+        struct inode *inode;
+        struct mqueue_inode_info *info;
+
+        if (u_mqstat != NULL) {
+                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
+                        return -EFAULT;
+                if (mqstat.mq_flags & (~O_NONBLOCK))
+                        return -EINVAL;
+        }
+
+        ret = -EBADF;
+        filp = fget(mqdes);
+        if (!filp)
+                goto out;
+
+        inode = filp->f_dentry->d_inode;
+        if (unlikely(filp->f_op != &mqueue_file_operations))
+                goto out_fput;
+        info = MQUEUE_I(inode);
+
+        spin_lock(&info->lock);
+
+        omqstat = info->attr;
+        omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
+        if (u_mqstat) {
+                if (mqstat.mq_flags & O_NONBLOCK)
+                        filp->f_flags |= O_NONBLOCK;
+                else
+                        filp->f_flags &= ~O_NONBLOCK;
+
+                inode->i_atime = inode->i_ctime = CURRENT_TIME;
+        }
+
+        spin_unlock(&info->lock);
+
+        ret = 0;
+        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
+                                                sizeof(struct mq_attr)))
+                ret = -EFAULT;
+
+out_fput:
+        fput(filp);
+out:
+        return ret;
+}
+
+static struct inode_operations mqueue_dir_inode_operations = {
+        .lookup = simple_lookup,
+        .create = mqueue_create,
+        .unlink = mqueue_unlink,
+};
+
+static struct file_operations mqueue_file_operations = {
+        .flush = mqueue_flush_file,
+        .poll = mqueue_poll_file,
+        .read = mqueue_read_file,
+};
+
+static struct super_operations mqueue_super_ops = {
+        .alloc_inode = mqueue_alloc_inode,
+        .destroy_inode = mqueue_destroy_inode,
+        .statfs = simple_statfs,
+        .delete_inode = mqueue_delete_inode,
+        .drop_inode = generic_delete_inode,
+};
+
+static struct file_system_type mqueue_fs_type = {
+        .name = "mqueue",
+        .get_sb = mqueue_get_sb,
+        .kill_sb = kill_litter_super,
+};
+
+static int msg_max_limit_min = DFLT_MSGMAX;
+static int msg_max_limit_max = HARD_MSGMAX;
+
+static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
+static int msg_maxsize_limit_max = INT_MAX;
+
+static ctl_table mq_sysctls[] = {
+        {
+                .ctl_name       = CTL_QUEUESMAX,
+                .procname       = "queues_max",
+                .data           = &queues_max,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec,
+        },
+        {
+                .ctl_name       = CTL_MSGMAX,
+                .procname       = "msg_max",
+                .data           = &msg_max,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec_minmax,
+                .extra1         = &msg_max_limit_min,
+                .extra2         = &msg_max_limit_max,
+        },
+        {
+                .ctl_name       = CTL_MSGSIZEMAX,
+                .procname       = "msgsize_max",
+                .data           = &msgsize_max,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec_minmax,
+                .extra1         = &msg_maxsize_limit_min,
+                .extra2         = &msg_maxsize_limit_max,
+        },
+        { .ctl_name = 0 }
+};
+
+static ctl_table mq_sysctl_dir[] = {
+        {
+                .ctl_name       = FS_MQUEUE,
+                .procname       = "mqueue",
+                .mode           = 0555,
+                .child          = mq_sysctls,
+        },
+        { .ctl_name = 0 }
+};
+
+static ctl_table mq_sysctl_root[] = {
+        {
+                .ctl_name       = CTL_FS,
+                .procname       = "fs",
+                .mode           = 0555,
+                .child          = mq_sysctl_dir,
+        },
+        { .ctl_name = 0 }
+};
+
+static int __init init_mqueue_fs(void)
+{
+        int error;
+
+        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
+                                sizeof(struct mqueue_inode_info), 0,
+                                SLAB_HWCACHE_ALIGN, init_once, NULL);
+        if (mqueue_inode_cachep == NULL)
+                return -ENOMEM;
+
+        /* ignore failues - they are not fatal */
+        mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
+
+        error = register_filesystem(&mqueue_fs_type);
+        if (error)
+                goto out_sysctl;
+
+        if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
+                error = PTR_ERR(mqueue_mnt);
+                goto out_filesystem;
+        }
+
+        /* internal initialization - not common for vfs */
+        queues_count = 0;
+        spin_lock_init(&mq_lock);
+
+        return 0;
+
+out_filesystem:
+        unregister_filesystem(&mqueue_fs_type);
+out_sysctl:
+        if (mq_sysctl_table)
+                unregister_sysctl_table(mq_sysctl_table);
+        if (kmem_cache_destroy(mqueue_inode_cachep)) {
+                printk(KERN_INFO
+                        "mqueue_inode_cache: not all structures were freed\n");
+        }
+        return error;
+}
+
+__initcall(init_mqueue_fs);