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 <mi...@kernel.org>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
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
