Merge tag 'armsoc-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

[karo-tx-linux.git] / include / linux / wait.h

diff --git a/include/linux/wait.h b/include/linux/wait.h
index d2f4ec7dba7c5f589a819446f23d29d5ca742238..ae71a769b89e3d9f706543a16cfd125120a52cb0 100644 (file)
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -137,6 +137,27 @@ 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);