[PATCH 1/3] rcuwait: Support timeouts

[Davidlohr Bueso <dave@stgolabs.net>]

Introduce rcuwait_wait_event_timeout(), with semantics equivalent
to calls for the simple and regular waitqueue counterparts.

Cc: peterz@infradead.org
Cc: mingo@redhat.com
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
Only cc'ing sched folks this patch to avoid spamming. fyi the actual user
comes up in patch 3 (cxl/mbox: Add background cmd handling machinery),
but found a few other potential users in various drivers, so more could
be added.

 include/linux/rcuwait.h | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h
index 8052d34da782..27343424225c 100644
--- a/include/linux/rcuwait.h
+++ b/include/linux/rcuwait.h
@@ -49,9 +49,9 @@ static inline void prepare_to_rcuwait(struct rcuwait *w)
 
 extern void finish_rcuwait(struct rcuwait *w);
 
-#define rcuwait_wait_event(w, condition, state)				\
+#define ___rcuwait_wait_event(w, condition, state, ret, cmd)		\
 ({									\
-	int __ret = 0;							\
+	long __ret = ret;						\
 	prepare_to_rcuwait(w);						\
 	for (;;) {							\
 		/*							\
@@ -67,10 +67,27 @@ extern void finish_rcuwait(struct rcuwait *w);
 			break;						\
 		}							\
 									\
-		schedule();						\
+		cmd;							\
 	}								\
 	finish_rcuwait(w);						\
 	__ret;								\
 })
 
+#define rcuwait_wait_event(w, condition, state)				\
+	___rcuwait_wait_event(w, condition, state, 0, schedule())
+
+#define __rcuwait_wait_event_timeout(w, condition, state, timeout)	\
+	___rcuwait_wait_event(w, ___wait_cond_timeout(condition),	\
+			      state, timeout,				\
+			      __ret = schedule_timeout(__ret))
+
+#define rcuwait_wait_event_timeout(w, condition, state, timeout)	\
+({									\
+	long __ret = timeout;						\
+	if (!___wait_cond_timeout(condition))				\
+		__ret = __rcuwait_wait_event_timeout(w, condition,	\
+						     state, timeout);	\
+	__ret;								\
+})
+
 #endif /* _LINUX_RCUWAIT_H_ */
-- 
2.40.1