4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Will Deacon <[email protected]> commit c2bc66082e1048c7573d72e62f597bdc5ce13fea upstream. [ Note, this is a Git cherry-pick of the following commit: 76ebbe78f739 ("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()") ... for easier x86 PTI code testing and back-porting. ] 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. Signed-off-by: Will Deacon <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- include/linux/compiler.h | 1 + 1 file changed, 1 insertion(+) --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -341,6 +341,7 @@ static __always_inline void __write_once __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)
