diff options
Diffstat (limited to 'kernel/futex/futex.h')
| -rw-r--r-- | kernel/futex/futex.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index 840302aefdfc..fe847f57dad5 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -154,6 +154,27 @@ extern struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, union fute extern void __futex_unqueue(struct futex_q *q); extern void __futex_queue(struct futex_q *q, struct futex_hash_bucket *hb); +extern int futex_unqueue(struct futex_q *q); + +/** + * futex_queue() - Enqueue the futex_q on the futex_hash_bucket + * @q: The futex_q to enqueue + * @hb: The destination hash bucket + * + * The hb->lock must be held by the caller, and is released here. A call to + * futex_queue() is typically paired with exactly one call to futex_unqueue(). The + * exceptions involve the PI related operations, which may use futex_unqueue_pi() + * or nothing if the unqueue is done as part of the wake process and the unqueue + * state is implicit in the state of woken task (see futex_wait_requeue_pi() for + * an example). + */ +static inline void futex_queue(struct futex_q *q, struct futex_hash_bucket *hb) + __releases(&hb->lock) +{ + __futex_queue(q, hb); + spin_unlock(&hb->lock); +} + extern void futex_unqueue_pi(struct futex_q *q); extern void wait_for_owner_exiting(int ret, struct task_struct *exiting); @@ -183,6 +204,19 @@ static inline void futex_hb_waiters_dec(struct futex_hash_bucket *hb) #endif } +static inline int futex_hb_waiters_pending(struct futex_hash_bucket *hb) +{ +#ifdef CONFIG_SMP + /* + * Full barrier (B), see the ordering comment above. + */ + smp_mb(); + return atomic_read(&hb->waiters); +#else + return 1; +#endif +} + extern struct futex_hash_bucket *futex_q_lock(struct futex_q *q); extern void futex_q_unlock(struct futex_hash_bucket *hb); |