*/
static inline int match_futex(union futex_key *key1, union futex_key *key2)
{
- return (key1->both.word == key2->both.word
+ return (key1 && key2
+ && key1->both.word == key2->both.word
&& key1->both.ptr == key2->both.ptr
&& key1->both.offset == key2->both.offset);
}
* @uaddr: virtual address of the futex
* @fshared: 0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
* @key: address where result is stored.
- * @rw: mapping needs to be read/write (values: VERIFY_READ,
- * VERIFY_WRITE)
*
* Returns a negative error code or 0
* The key words are stored in *key on success.
* lock_page() might sleep, the caller should not hold a spinlock.
*/
static int
-get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
+get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
{
unsigned long address = (unsigned long)uaddr;
struct mm_struct *mm = current->mm;
* but access_ok() should be faster than find_vma()
*/
if (!fshared) {
- if (unlikely(!access_ok(rw, uaddr, sizeof(u32))))
+ if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))))
return -EFAULT;
key->private.mm = mm;
key->private.address = address;
}
again:
- err = get_user_pages_fast(address, 1, rw == VERIFY_WRITE, &page);
+ err = get_user_pages_fast(address, 1, 1, &page);
if (err < 0)
return err;
*/
static int fault_in_user_writeable(u32 __user *uaddr)
{
- int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
- 1, 1, 0, NULL, NULL);
+ struct mm_struct *mm = current->mm;
+ int ret;
+
+ down_read(&mm->mmap_sem);
+ ret = get_user_pages(current, mm, (unsigned long)uaddr,
+ 1, 1, 0, NULL, NULL);
+ up_read(&mm->mmap_sem);
+
return ret < 0 ? ret : 0;
}
* and has cleaned up the pi_state already
*/
if (pi_state->owner) {
- spin_lock_irq(&pi_state->owner->pi_lock);
+ raw_spin_lock_irq(&pi_state->owner->pi_lock);
list_del_init(&pi_state->list);
- spin_unlock_irq(&pi_state->owner->pi_lock);
+ raw_spin_unlock_irq(&pi_state->owner->pi_lock);
rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner);
}
* pi_state_list anymore, but we have to be careful
* versus waiters unqueueing themselves:
*/
- spin_lock_irq(&curr->pi_lock);
+ raw_spin_lock_irq(&curr->pi_lock);
while (!list_empty(head)) {
next = head->next;
pi_state = list_entry(next, struct futex_pi_state, list);
key = pi_state->key;
hb = hash_futex(&key);
- spin_unlock_irq(&curr->pi_lock);
+ raw_spin_unlock_irq(&curr->pi_lock);
spin_lock(&hb->lock);
- spin_lock_irq(&curr->pi_lock);
+ raw_spin_lock_irq(&curr->pi_lock);
/*
* We dropped the pi-lock, so re-check whether this
* task still owns the PI-state:
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
pi_state->owner = NULL;
- spin_unlock_irq(&curr->pi_lock);
+ raw_spin_unlock_irq(&curr->pi_lock);
rt_mutex_unlock(&pi_state->pi_mutex);
spin_unlock(&hb->lock);
- spin_lock_irq(&curr->pi_lock);
+ raw_spin_lock_irq(&curr->pi_lock);
}
- spin_unlock_irq(&curr->pi_lock);
+ raw_spin_unlock_irq(&curr->pi_lock);
}
static int
return -EINVAL;
WARN_ON(!atomic_read(&pi_state->refcount));
- WARN_ON(pid && pi_state->owner &&
- pi_state->owner->pid != pid);
+
+ /*
+ * When pi_state->owner is NULL then the owner died
+ * and another waiter is on the fly. pi_state->owner
+ * is fixed up by the task which acquires
+ * pi_state->rt_mutex.
+ *
+ * We do not check for pid == 0 which can happen when
+ * the owner died and robust_list_exit() cleared the
+ * TID.
+ */
+ if (pid && pi_state->owner) {
+ /*
+ * Bail out if user space manipulated the
+ * futex value.
+ */
+ if (pid != task_pid_vnr(pi_state->owner))
+ return -EINVAL;
+ }
atomic_inc(&pi_state->refcount);
*ps = pi_state;
* change of the task flags, we do this protected by
* p->pi_lock:
*/
- spin_lock_irq(&p->pi_lock);
+ raw_spin_lock_irq(&p->pi_lock);
if (unlikely(p->flags & PF_EXITING)) {
/*
* The task is on the way out. When PF_EXITPIDONE is
*/
int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN;
- spin_unlock_irq(&p->pi_lock);
+ raw_spin_unlock_irq(&p->pi_lock);
put_task_struct(p);
return ret;
}
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &p->pi_state_list);
pi_state->owner = p;
- spin_unlock_irq(&p->pi_lock);
+ raw_spin_unlock_irq(&p->pi_lock);
put_task_struct(p);
if (!pi_state)
return -EINVAL;
- spin_lock(&pi_state->pi_mutex.wait_lock);
+ /*
+ * If current does not own the pi_state then the futex is
+ * inconsistent and user space fiddled with the futex value.
+ */
+ if (pi_state->owner != current)
+ return -EINVAL;
+
+ raw_spin_lock(&pi_state->pi_mutex.wait_lock);
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
/*
else if (curval != uval)
ret = -EINVAL;
if (ret) {
- spin_unlock(&pi_state->pi_mutex.wait_lock);
+ raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
return ret;
}
}
- spin_lock_irq(&pi_state->owner->pi_lock);
+ raw_spin_lock_irq(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
- spin_unlock_irq(&pi_state->owner->pi_lock);
+ raw_spin_unlock_irq(&pi_state->owner->pi_lock);
- spin_lock_irq(&new_owner->pi_lock);
+ raw_spin_lock_irq(&new_owner->pi_lock);
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &new_owner->pi_state_list);
pi_state->owner = new_owner;
- spin_unlock_irq(&new_owner->pi_lock);
+ raw_spin_unlock_irq(&new_owner->pi_lock);
- spin_unlock(&pi_state->pi_mutex.wait_lock);
+ raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
rt_mutex_unlock(&pi_state->pi_mutex);
return 0;
if (!bitset)
return -EINVAL;
- ret = get_futex_key(uaddr, fshared, &key, VERIFY_READ);
+ ret = get_futex_key(uaddr, fshared, &key);
if (unlikely(ret != 0))
goto out;
int ret, op_ret;
retry:
- ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+ ret = get_futex_key(uaddr1, fshared, &key1);
if (unlikely(ret != 0))
goto out;
- ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+ ret = get_futex_key(uaddr2, fshared, &key2);
if (unlikely(ret != 0))
goto out_put_key1;
hb1 = hash_futex(&key1);
hb2 = hash_futex(&key2);
- double_lock_hb(hb1, hb2);
retry_private:
+ double_lock_hb(hb1, hb2);
op_ret = futex_atomic_op_inuser(op, uaddr2);
if (unlikely(op_ret < 0)) {
plist_add(&q->list, &hb2->chain);
q->lock_ptr = &hb2->lock;
#ifdef CONFIG_DEBUG_PI_LIST
- q->list.plist.lock = &hb2->lock;
+ q->list.plist.spinlock = &hb2->lock;
#endif
}
get_futex_key_refs(key2);
void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
struct futex_hash_bucket *hb)
{
- drop_futex_key_refs(&q->key);
get_futex_key_refs(key);
q->key = *key;
q->lock_ptr = &hb->lock;
#ifdef CONFIG_DEBUG_PI_LIST
- q->list.plist.lock = &hb->lock;
+ q->list.plist.spinlock = &hb->lock;
#endif
wake_up_state(q->task, TASK_NORMAL);
pi_state = NULL;
}
- ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+ ret = get_futex_key(uaddr1, fshared, &key1);
if (unlikely(ret != 0))
goto out;
- ret = get_futex_key(uaddr2, fshared, &key2,
- requeue_pi ? VERIFY_WRITE : VERIFY_READ);
+ ret = get_futex_key(uaddr2, fshared, &key2);
if (unlikely(ret != 0))
goto out_put_key1;
*/
if (ret == 1) {
WARN_ON(pi_state);
+ drop_count++;
task_count++;
ret = get_futex_value_locked(&curval2, uaddr2);
if (!ret)
if (ret == 1) {
/* We got the lock. */
requeue_pi_wake_futex(this, &key2, hb2);
+ drop_count++;
continue;
} else if (ret) {
/* -EDEADLK */
plist_node_init(&q->list, prio);
#ifdef CONFIG_DEBUG_PI_LIST
- q->list.plist.lock = &hb->lock;
+ q->list.plist.spinlock = &hb->lock;
#endif
plist_add(&q->list, &hb->chain);
q->task = current;
* itself.
*/
if (pi_state->owner != NULL) {
- spin_lock_irq(&pi_state->owner->pi_lock);
+ raw_spin_lock_irq(&pi_state->owner->pi_lock);
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
- spin_unlock_irq(&pi_state->owner->pi_lock);
+ raw_spin_unlock_irq(&pi_state->owner->pi_lock);
}
pi_state->owner = newowner;
- spin_lock_irq(&newowner->pi_lock);
+ raw_spin_lock_irq(&newowner->pi_lock);
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &newowner->pi_state_list);
- spin_unlock_irq(&newowner->pi_lock);
+ raw_spin_unlock_irq(&newowner->pi_lock);
return 0;
/*
static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
struct hrtimer_sleeper *timeout)
{
- queue_me(q, hb);
-
/*
- * There might have been scheduling since the queue_me(), as we
- * cannot hold a spinlock across the get_user() in case it
- * faults, and we cannot just set TASK_INTERRUPTIBLE state when
- * queueing ourselves into the futex hash. This code thus has to
- * rely on the futex_wake() code removing us from hash when it
- * wakes us up.
+ * The task state is guaranteed to be set before another task can
+ * wake it. set_current_state() is implemented using set_mb() and
+ * queue_me() calls spin_unlock() upon completion, both serializing
+ * access to the hash list and forcing another memory barrier.
*/
set_current_state(TASK_INTERRUPTIBLE);
+ queue_me(q, hb);
/* Arm the timer */
if (timeout) {
}
/*
- * !plist_node_empty() is safe here without any lock.
- * q.lock_ptr != 0 is not safe, because of ordering against wakeup.
+ * If we have been removed from the hash list, then another task
+ * has tried to wake us, and we can skip the call to schedule().
*/
if (likely(!plist_node_empty(&q->list))) {
/*
*/
retry:
q->key = FUTEX_KEY_INIT;
- ret = get_futex_key(uaddr, fshared, &q->key, VERIFY_READ);
+ ret = get_futex_key(uaddr, fshared, &q->key);
if (unlikely(ret != 0))
return ret;
current->timer_slack_ns);
}
+retry:
/* Prepare to wait on uaddr. */
ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
if (ret)
goto out_put_key;
/*
- * We expect signal_pending(current), but another thread may
- * have handled it for us already.
+ * We expect signal_pending(current), but we might be the
+ * victim of a spurious wakeup as well.
*/
+ if (!signal_pending(current)) {
+ put_futex_key(fshared, &q.key);
+ goto retry;
+ }
+
ret = -ERESTARTSYS;
if (!abs_time)
goto out_put_key;
q.requeue_pi_key = NULL;
retry:
q.key = FUTEX_KEY_INIT;
- ret = get_futex_key(uaddr, fshared, &q.key, VERIFY_WRITE);
+ ret = get_futex_key(uaddr, fshared, &q.key);
if (unlikely(ret != 0))
goto out;
/* Unqueue and drop the lock */
unqueue_me_pi(&q);
- goto out;
+ goto out_put_key;
out_unlock_put_key:
queue_unlock(&q, hb);
if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
return -EPERM;
- ret = get_futex_key(uaddr, fshared, &key, VERIFY_WRITE);
+ ret = get_futex_key(uaddr, fshared, &key);
if (unlikely(ret != 0))
goto out;
* Unqueue the futex_q and determine which it was.
*/
plist_del(&q->list, &q->list.plist);
- drop_futex_key_refs(&q->key);
+ /* Handle spurious wakeups gracefully */
+ ret = -EWOULDBLOCK;
if (timeout && !timeout->task)
ret = -ETIMEDOUT;
- else
+ else if (signal_pending(current))
ret = -ERESTARTNOINTR;
}
return ret;
rt_waiter.task = NULL;
key2 = FUTEX_KEY_INIT;
- ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+ ret = get_futex_key(uaddr2, fshared, &key2);
if (unlikely(ret != 0))
goto out;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff