From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 10 Sep 2008 07:57:35 +0000 (+0200)
Subject: lockdep: add might_lock() / might_lock_read()
X-Git-Tag: v2.6.29-rc1~572^2~4^4~15
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=76b189e91845eab3a9d52bb97f971d312d25652d;p=karo-tx-linux.git

lockdep: add might_lock() / might_lock_read()

useful to establish a lock dependency in case the actual dependency is
rare or hard to trigger.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 331e5f1c2d8e..0aa657aa8a1e 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -480,4 +480,22 @@ static inline void print_irqtrace_events(struct task_struct *curr)
 # define lock_map_release(l)			do { } while (0)
 #endif
 
+#ifdef CONFIG_PROVE_LOCKING
+# define might_lock(lock) 						\
+do {									\
+	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
+	lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);	\
+	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
+} while (0)
+# define might_lock_read(lock) 						\
+do {									\
+	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
+	lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);	\
+	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
+} while (0)
+#else
+# define might_lock(lock) do { } while (0)
+# define might_lock_read(lock) do { } while (0)
+#endif
+
 #endif /* __LINUX_LOCKDEP_H */