Add wait_event_timeout()

There appears to be one case missing from the wait_event() family -
the uninterruptible timeout wait.  The following patch adds this.

This wait is particularly useful when (eg) you wish to pass work off
to an interrupt handler to perform, but also want to know if the
hardware has decided to go gaga under you.  You don't want to sit
around waiting for something that'll never happen - you want to go
and wack the gremlin which caused the failure and retry.

--- linux/include/linux/wait.h.orig	2004-09-21 13:07:07.000000000 +0100
+++ linux/include/linux/wait.h	2004-09-25 09:33:19.000000000 +0100
@@ -156,6 +156,29 @@
 	__wait_event(wq, condition);					\
 } while (0)
 
+#define __wait_event_timeout(wq, condition, ret)			\
+do {									\
+	DEFINE_WAIT(__wait);						\
+									\
+	for (;;) {							\
+		prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		ret = schedule_timeout(ret);				\
+		if (!ret)						\
+			break;						\
+	}								\
+	finish_wait(&wq, &__wait);					\
+} while (0)
+
+#define wait_event_timeout(wq, condition, timeout)			\
+({									\
+	long __ret = timeout;						\
+	if (!(condition)) 						\
+		__wait_event_timeout(wq, condition, __ret);		\
+	__ret;								\
+})
+
 #define __wait_event_interruptible(wq, condition, ret)			\
 do {									\
 	DEFINE_WAIT(__wait);						\

-
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