Commit-ID: 76ebbe78f7390aee075a7f3768af197ded1bdfbb Gitweb: https://git.kernel.org/tip/76ebbe78f7390aee075a7f3768af197ded1bdfbb Author: Will Deacon <will.dea...@arm.com> AuthorDate: Tue, 24 Oct 2017 11:22:47 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 24 Oct 2017 13:17:32 +0200
locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE() 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 <will.dea...@arm.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.dea...@arm.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/linux/compiler.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 0808318..7d7b77d 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)
