[PATCH 13/25] mutex: Provide mutex_is_contended

[Peter Zijlstra]

Usable for lock-breaks and such.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 include/linux/mutex.h |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6/include/linux/mutex.h
===================================================================
--- linux-2.6.orig/include/linux/mutex.h
+++ linux-2.6/include/linux/mutex.h
@@ -126,6 +126,11 @@ static inline int mutex_is_locked(struct
 	return atomic_read(&lock->count) != 1;
 }
 
+static inline int mutex_is_contended(struct mutex *lock)
+{
+	return atomic_read(&lock->count) < 0;
+}
+
 /*
  * See kernel/mutex.c for detailed documentation of these APIs.
  * Also see Documentation/mutex-design.txt.


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