diff options
Diffstat (limited to 'include/linux/wait.h')
| -rw-r--r-- | include/linux/wait.h | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h index 1e1bf9f963a9..6aa09a875fbd 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -107,6 +107,27 @@ static inline int waitqueue_active(wait_queue_head_t *q) return !list_empty(&q->task_list); } +/** + * wq_has_sleeper - check if there are any waiting processes + * @wq: wait queue head + * + * Returns true if wq has waiting processes + * + * Please refer to the comment for waitqueue_active. + */ +static inline bool wq_has_sleeper(wait_queue_head_t *wq) +{ + /* + * We need to be sure we are in sync with the + * add_wait_queue modifications to the wait queue. + * + * This memory barrier should be paired with one on the + * waiting side. + */ + smp_mb(); + return waitqueue_active(wq); +} + extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait); extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); |