-static int futex_close(struct inode *inode, struct file *filp)
-{
- struct futex_q *q = filp->private_data;
-
- unqueue_me(q);
- kfree(q);
-
- return 0;
-}
-
-/* This is one-shot: once it's gone off you need a new fd */
-static unsigned int futex_poll(struct file *filp,
- struct poll_table_struct *wait)
-{
- struct futex_q *q = filp->private_data;
- int ret = 0;
-
- poll_wait(filp, &q->waiters, wait);
-
- /*
- * plist_node_empty() is safe here without any lock.
- * q->lock_ptr != 0 is not safe, because of ordering against wakeup.
- */
- if (plist_node_empty(&q->list))
- ret = POLLIN | POLLRDNORM;
-
- return ret;
-}
-
-static const struct file_operations futex_fops = {
- .release = futex_close,
- .poll = futex_poll,
-};
-
-/*
- * Signal allows caller to avoid the race which would occur if they
- * set the sigio stuff up afterwards.
- */
-static int futex_fd(u32 __user *uaddr, int signal)
-{
- struct futex_q *q;
- struct file *filp;
- int ret, err;
- struct rw_semaphore *fshared;
- static unsigned long printk_interval;
-
- if (printk_timed_ratelimit(&printk_interval, 60 * 60 * 1000)) {
- printk(KERN_WARNING "Process `%s' used FUTEX_FD, which "
- "will be removed from the kernel in June 2007\n",
- current->comm);
- }
-
- ret = -EINVAL;
- if (!valid_signal(signal))
- goto out;
-
- ret = get_unused_fd();
- if (ret < 0)
- goto out;
- filp = get_empty_filp();
- if (!filp) {
- put_unused_fd(ret);
- ret = -ENFILE;
- goto out;
- }
- filp->f_op = &futex_fops;
- filp->f_path.mnt = mntget(futex_mnt);
- filp->f_path.dentry = dget(futex_mnt->mnt_root);
- filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping;
-
- if (signal) {
- err = __f_setown(filp, task_pid(current), PIDTYPE_PID, 1);
- if (err < 0) {
- goto error;
- }
- filp->f_owner.signum = signal;
- }
-
- q = kmalloc(sizeof(*q), GFP_KERNEL);
- if (!q) {
- err = -ENOMEM;
- goto error;
- }
- q->pi_state = NULL;
-
- fshared = ¤t->mm->mmap_sem;
- down_read(fshared);
- err = get_futex_key(uaddr, fshared, &q->key);
-
- if (unlikely(err != 0)) {
- up_read(fshared);
- kfree(q);
- goto error;
- }
-
- /*
- * queue_me() must be called before releasing mmap_sem, because
- * key->shared.inode needs to be referenced while holding it.
- */
- filp->private_data = q;
-
- queue_me(q, ret, filp);
- up_read(fshared);
-
- /* Now we map fd to filp, so userspace can access it */
- fd_install(ret, filp);
-out:
- return ret;
-error:
- put_unused_fd(ret);
- put_filp(filp);
- ret = err;
- goto out;
-}
-