/* Key which the futex is hashed on: */
union futex_key key;
- /* For fd, sigio sent using these: */
- int fd;
- struct file *filp;
-
/* Optional priority inheritance state: */
struct futex_pi_state *pi_state;
struct task_struct *task;
static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS];
-/* Futex-fs vfsmount entry: */
-static struct vfsmount *futex_mnt;
-
/*
* Take mm->mmap_sem, when futex is shared
*/
static void wake_futex(struct futex_q *q)
{
plist_del(&q->list, &q->list.plist);
- if (q->filp)
- send_sigio(&q->filp->f_owner, q->fd, POLL_IN);
/*
* The lock in wake_up_all() is a crucial memory barrier after the
* plist_del() and also before assigning to q->lock_ptr.
}
/* The key must be already stored in q->key. */
-static inline struct futex_hash_bucket *
-queue_lock(struct futex_q *q, int fd, struct file *filp)
+static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
{
struct futex_hash_bucket *hb;
- q->fd = fd;
- q->filp = filp;
-
init_waitqueue_head(&q->waiters);
get_futex_key_refs(&q->key);
return hb;
}
-static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
+static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
{
int prio;
* exactly once. They are called with the hashed spinlock held.
*/
-/* The key must be already stored in q->key. */
-static void queue_me(struct futex_q *q, int fd, struct file *filp)
-{
- struct futex_hash_bucket *hb;
-
- hb = queue_lock(q, fd, filp);
- __queue_me(q, hb);
-}
-
/* Return 1 if we were still queued (ie. 0 means we were woken) */
static int unqueue_me(struct futex_q *q)
{
if (unlikely(ret != 0))
goto out_release_sem;
- hb = queue_lock(&q, -1, NULL);
+ hb = queue_lock(&q);
/*
* Access the page AFTER the futex is queued.
goto out_unlock_release_sem;
/* Only actually queue if *uaddr contained val. */
- __queue_me(&q, hb);
+ queue_me(&q, hb);
/*
* Now the futex is queued and we have checked the data, we
goto out_release_sem;
retry_unlocked:
- hb = queue_lock(&q, -1, NULL);
+ hb = queue_lock(&q);
retry_locked:
ret = lock_taken = 0;
/*
* Only actually queue now that the atomic ops are done:
*/
- __queue_me(&q, hb);
+ queue_me(&q, hb);
/*
* Now the futex is queued and we have checked the data, we
return ret;
}
-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;
-}
-
/*
* Support for robust futexes: the kernel cleans up held futexes at
* thread exit time.
case FUTEX_WAKE_BITSET:
ret = futex_wake(uaddr, fshared, val, val3);
break;
- case FUTEX_FD:
- /* non-zero val means F_SETOWN(getpid()) & F_SETSIG(val) */
- ret = futex_fd(uaddr, val);
- break;
case FUTEX_REQUEUE:
ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL);
break;
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
}
-static int futexfs_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data,
- struct vfsmount *mnt)
-{
- return get_sb_pseudo(fs_type, "futex", NULL, FUTEXFS_SUPER_MAGIC, mnt);
-}
-
-static struct file_system_type futex_fs_type = {
- .name = "futexfs",
- .get_sb = futexfs_get_sb,
- .kill_sb = kill_anon_super,
-};
-
static int __init futex_init(void)
{
u32 curval;
spin_lock_init(&futex_queues[i].lock);
}
- i = register_filesystem(&futex_fs_type);
- if (i)
- return i;
-
- futex_mnt = kern_mount(&futex_fs_type);
- if (IS_ERR(futex_mnt)) {
- unregister_filesystem(&futex_fs_type);
- return PTR_ERR(futex_mnt);
- }
-
return 0;
}
__initcall(futex_init);
projects / linux-2.6 / commitdiff