[tip:locking/core] tools/lib/lockdep: Add userspace version of READ_ONCE()

[tip-bot for Alfredo Alvarez Fernandez]

Commit-ID:  9d5a23ac8e0ede14a2b23740d231727ba5be483a
Gitweb:     http://git.kernel.org/tip/9d5a23ac8e0ede14a2b23740d231727ba5be483a
Author:     Alfredo Alvarez Fernandez <alfredoalvarezfernandez@xxxxxxxxx>
AuthorDate: Fri, 19 Feb 2016 07:48:51 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 29 Feb 2016 10:29:27 +0100

tools/lib/lockdep: Add userspace version of READ_ONCE()

This was added to the kernel code in <1658d35ead5d> ("list: Use
READ_ONCE() when testing for empty lists").

There's nothing special we need to do about it in userspace.

Signed-off-by: Alfredo Alvarez Fernandez <alfredoalvarezfernandez@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1455864533-7536-2-git-send-email-alfredoalvarezernandez@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/lib/lockdep/uinclude/linux/compiler.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/lockdep/uinclude/linux/compiler.h b/tools/lib/lockdep/uinclude/linux/compiler.h
index 6386dc3..fd3e56a 100644
--- a/tools/lib/lockdep/uinclude/linux/compiler.h
+++ b/tools/lib/lockdep/uinclude/linux/compiler.h
@@ -3,6 +3,7 @@
 
 #define __used		__attribute__((__unused__))
 #define unlikely
+#define READ_ONCE(x) (x)
 #define WRITE_ONCE(x, val) x=(val)
 #define RCU_INIT_POINTER(p, v) p=(v)