q->lock_ptr = NULL;
}
-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
+static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
+ struct futex_hash_bucket *hb)
{
struct task_struct *new_owner;
struct futex_pi_state *pi_state = this->pi_state;
u32 uninitialized_var(curval), newval;
+ WAKE_Q(wake_q);
+ bool deboost;
int ret = 0;
if (!pi_state)
raw_spin_unlock_irq(&new_owner->pi_lock);
raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
- rt_mutex_unlock(&pi_state->pi_mutex);
+
+ deboost = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
+
+ /*
+ * First unlock HB so the waiter does not spin on it once he got woken
+ * up. Second wake up the waiter before the priority is adjusted. If we
+ * deboost first (and lose our higher priority), then the task might get
+ * scheduled away before the wake up can take place.
+ */
+ spin_unlock(&hb->lock);
+ wake_up_q(&wake_q);
+ if (deboost)
+ rt_mutex_adjust_prio(current);
return 0;
}
*/
match = futex_top_waiter(hb, &key);
if (match) {
- ret = wake_futex_pi(uaddr, uval, match);
+ ret = wake_futex_pi(uaddr, uval, match, hb);
+ /*
+ * In case of success wake_futex_pi dropped the hash
+ * bucket lock.
+ */
+ if (!ret)
+ goto out_putkey;
/*
* The atomic access to the futex value generated a
* pagefault, so retry the user-access and the wakeup:
*/
if (ret == -EFAULT)
goto pi_faulted;
+ /*
+ * wake_futex_pi has detected invalid state. Tell user
+ * space.
+ */
goto out_unlock;
}
out_unlock:
spin_unlock(&hb->lock);
+out_putkey:
put_futex_key(&key);
return ret;
* of task. We do not use the spin_xx_mutex() variants here as we are
* outside of the debug path.)
*/
-static void rt_mutex_adjust_prio(struct task_struct *task)
+void rt_mutex_adjust_prio(struct task_struct *task)
{
unsigned long flags;
*/
prerequeue_top_waiter = rt_mutex_top_waiter(lock);
- /* [7] Requeue the waiter in the lock waiter list. */
+ /* [7] Requeue the waiter in the lock waiter tree. */
rt_mutex_dequeue(lock, waiter);
waiter->prio = task->prio;
rt_mutex_enqueue(lock, waiter);
/*
* The waiter became the new top (highest priority)
* waiter on the lock. Replace the previous top waiter
- * in the owner tasks pi waiters list with this waiter
+ * in the owner tasks pi waiters tree with this waiter
* and adjust the priority of the owner.
*/
rt_mutex_dequeue_pi(task, prerequeue_top_waiter);
/*
* The waiter was the top waiter on the lock, but is
* no longer the top prority waiter. Replace waiter in
- * the owner tasks pi waiters list with the new top
+ * the owner tasks pi waiters tree with the new top
* (highest priority) waiter and adjust the priority
* of the owner.
* The new top waiter is stored in @waiter so that
*
* @lock: The lock to be acquired.
* @task: The task which wants to acquire the lock
- * @waiter: The waiter that is queued to the lock's wait list if the
+ * @waiter: The waiter that is queued to the lock's wait tree if the
* callsite called task_blocked_on_lock(), otherwise NULL
*/
static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
/*
* If @waiter != NULL, @task has already enqueued the waiter
- * into @lock waiter list. If @waiter == NULL then this is a
+ * into @lock waiter tree. If @waiter == NULL then this is a
* trylock attempt.
*/
if (waiter) {
/*
* We can acquire the lock. Remove the waiter from the
- * lock waiters list.
+ * lock waiters tree.
*/
rt_mutex_dequeue(lock, waiter);
* No waiters. Take the lock without the
* pi_lock dance.@task->pi_blocked_on is NULL
* and we have no waiters to enqueue in @task
- * pi waiters list.
+ * pi waiters tree.
*/
goto takeit;
}
/*
* Finish the lock acquisition. @task is the new owner. If
* other waiters exist we have to insert the highest priority
- * waiter into @task->pi_waiters list.
+ * waiter into @task->pi_waiters tree.
*/
if (rt_mutex_has_waiters(lock))
rt_mutex_enqueue_pi(task, rt_mutex_top_waiter(lock));
}
/*
- * Wake up the next waiter on the lock.
- *
- * Remove the top waiter from the current tasks pi waiter list and
- * wake it up.
+ * Remove the top waiter from the current tasks pi waiter tree and
+ * queue it up.
*
* Called with lock->wait_lock held.
*/
-static void wakeup_next_waiter(struct rt_mutex *lock)
+static void mark_wakeup_next_waiter(struct wake_q_head *wake_q,
+ struct rt_mutex *lock)
{
struct rt_mutex_waiter *waiter;
unsigned long flags;
raw_spin_unlock_irqrestore(¤t->pi_lock, flags);
- /*
- * It's safe to dereference waiter as it cannot go away as
- * long as we hold lock->wait_lock. The waiter task needs to
- * acquire it in order to dequeue the waiter.
- */
- wake_up_process(waiter->task);
+ wake_q_add(wake_q, waiter->task);
}
/*
}
/*
- * Slow path to release a rt-mutex:
+ * Slow path to release a rt-mutex.
+ * Return whether the current task needs to undo a potential priority boosting.
*/
-static void __sched
-rt_mutex_slowunlock(struct rt_mutex *lock)
+static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
+ struct wake_q_head *wake_q)
{
raw_spin_lock(&lock->wait_lock);
while (!rt_mutex_has_waiters(lock)) {
/* Drops lock->wait_lock ! */
if (unlock_rt_mutex_safe(lock) == true)
- return;
+ return false;
/* Relock the rtmutex and try again */
raw_spin_lock(&lock->wait_lock);
}
/*
* The wakeup next waiter path does not suffer from the above
* race. See the comments there.
+ *
+ * Queue the next waiter for wakeup once we release the wait_lock.
*/
- wakeup_next_waiter(lock);
+ mark_wakeup_next_waiter(wake_q, lock);
raw_spin_unlock(&lock->wait_lock);
- /* Undo pi boosting if necessary: */
- rt_mutex_adjust_prio(current);
+ /* check PI boosting */
+ return true;
}
/*
static inline void
rt_mutex_fastunlock(struct rt_mutex *lock,
- void (*slowfn)(struct rt_mutex *lock))
+ bool (*slowfn)(struct rt_mutex *lock,
+ struct wake_q_head *wqh))
{
- if (likely(rt_mutex_cmpxchg(lock, current, NULL)))
+ WAKE_Q(wake_q);
+
+ if (likely(rt_mutex_cmpxchg(lock, current, NULL))) {
rt_mutex_deadlock_account_unlock(current);
- else
- slowfn(lock);
+
+ } else {
+ bool deboost = slowfn(lock, &wake_q);
+
+ wake_up_q(&wake_q);
+
+ /* Undo pi boosting if necessary: */
+ if (deboost)
+ rt_mutex_adjust_prio(current);
+ }
}
/**
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
+/**
+ * rt_mutex_futex_unlock - Futex variant of rt_mutex_unlock
+ * @lock: the rt_mutex to be unlocked
+ *
+ * Returns: true/false indicating whether priority adjustment is
+ * required or not.
+ */
+bool __sched rt_mutex_futex_unlock(struct rt_mutex *lock,
+ struct wake_q_head *wqh)
+{
+ if (likely(rt_mutex_cmpxchg(lock, current, NULL))) {
+ rt_mutex_deadlock_account_unlock(current);
+ return false;
+ }
+ return rt_mutex_slowunlock(lock, wqh);
+}
+
/**
* rt_mutex_destroy - mark a mutex unusable
* @lock: the mutex to be destroyed
projects / karo-tx-linux.git / commitdiff