[PATCH v2 2/3] locking/mutex: Introduce mutex_init_with_key()

[Bart Van Assche <bvanassche@acm.org>]

The following pattern occurs 5 times in kernel drivers:

	lockdep_register_key(key);
	__mutex_init(mutex, name, key);

In several cases the 'name' argument matches #mutex. Hence, introduce
the mutex_init_with_key() macro. This macro derives the 'name' argument
from the 'mutex' argument.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 include/linux/mutex.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index ef617089db19..2bf91b57591b 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -64,6 +64,17 @@ do {									\
 	__mutex_init((mutex), #mutex, &__key);				\
 } while (0)
 
+/**
+ * mutex_init_with_key - initialize a mutex with a given lockdep key
+ * @mutex: the mutex to be initialized
+ * @key: the lockdep key to be associated with the mutex
+ *
+ * Initialize the mutex to the unlocked state.
+ *
+ * It is not allowed to initialize an already locked mutex.
+ */
+#define mutex_init_with_key(mutex, key) __mutex_init((mutex), #mutex, (key))
+
 #ifndef CONFIG_PREEMPT_RT
 #define __MUTEX_INITIALIZER(lockname) \
 		{ .owner = ATOMIC_LONG_INIT(0) \