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Diffstat (limited to 'include/linux/rcuwait.h')
-rw-r--r--include/linux/rcuwait.h32
1 files changed, 26 insertions, 6 deletions
diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h
index 2ffe1ee6d482..61c56cca95c4 100644
--- a/include/linux/rcuwait.h
+++ b/include/linux/rcuwait.h
@@ -25,16 +25,38 @@ static inline void rcuwait_init(struct rcuwait *w)
w->task = NULL;
}
-extern void rcuwait_wake_up(struct rcuwait *w);
+/*
+ * Note: this provides no serialization and, just as with waitqueues,
+ * requires care to estimate as to whether or not the wait is active.
+ */
+static inline int rcuwait_active(struct rcuwait *w)
+{
+ return !!rcu_access_pointer(w->task);
+}
+
+extern int rcuwait_wake_up(struct rcuwait *w);
/*
* The caller is responsible for locking around rcuwait_wait_event(),
- * such that writes to @task are properly serialized.
+ * and [prepare_to/finish]_rcuwait() such that writes to @task are
+ * properly serialized.
*/
+
+static inline void prepare_to_rcuwait(struct rcuwait *w)
+{
+ rcu_assign_pointer(w->task, current);
+}
+
+static inline void finish_rcuwait(struct rcuwait *w)
+{
+ rcu_assign_pointer(w->task, NULL);
+ __set_current_state(TASK_RUNNING);
+}
+
#define rcuwait_wait_event(w, condition, state) \
({ \
int __ret = 0; \
- rcu_assign_pointer((w)->task, current); \
+ prepare_to_rcuwait(w); \
for (;;) { \
/* \
* Implicit barrier (A) pairs with (B) in \
@@ -51,9 +73,7 @@ extern void rcuwait_wake_up(struct rcuwait *w);
\
schedule(); \
} \
- \
- WRITE_ONCE((w)->task, NULL); \
- __set_current_state(TASK_RUNNING); \
+ finish_rcuwait(w); \
__ret; \
})