In preparation for the removal of lockless_dereference(), which is the same as READ_ONCE() on all architectures other than Alpha, add an implicit smp_read_barrier_depends() to READ_ONCE() so that it can be used to head dependency chains on all architectures.
Cc: Ingo Molnar <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Signed-off-by: Will Deacon <[email protected]> --- include/linux/compiler.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 08083186e54f..7d7b77da9716 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -242,6 +242,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __read_once_size(&(x), __u.__c, sizeof(x)); \ else \ __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ + smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ __u.__val; \ }) #define READ_ONCE(x) __READ_ONCE(x, 1) -- 2.1.4
