Commit 88e77dc6 authored Feb 20, 2018 by Peter Zijlstra Committed by Ingo Molnar Feb 21, 2018

locking/mutex: Add comment to __mutex_owner() to deter usage

Attempt to deter usage, this is not a public interface. It is entirely
possible to implement a conformant mutex without having this owner
field (in fact, we used to have that).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 91ab883e

include/linux/mutex.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -66,6 +66,11 @@ struct mutex {
		#endif
		};

		/*
		* Internal helper function; C doesn't allow us to hide it :/
		*
		* DO NOT USE (outside of mutex code).
		*/
		static inline struct task_struct __mutex_owner(struct mutex lock)
		{
		return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07);