From e3e72ab80a3fac0b88e07d358a2c75724ccd66b4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 18 Sep 2015 13:22:52 +0200 Subject: atomic: Implement atomic_read_ctrl() Provide atomic_read_ctrl() to mirror READ_ONCE_CTRL(), such that we can more conveniently use atomics in control dependencies. Since we can assume atomic_read() implies a READ_ONCE(), we must only emit an extra smp_read_barrier_depends() in order to upgrade to READ_ONCE_CTRL() semantics. Requested-by: Dmitry Vyukov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/20150918115637.GM3604@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- include/asm-generic/atomic-long.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h index c7a5c1ad2ed3..8942cdc676a7 100644 --- a/include/asm-generic/atomic-long.h +++ b/include/asm-generic/atomic-long.h @@ -35,7 +35,7 @@ typedef atomic_t atomic_long_t; #endif #define ATOMIC_LONG_READ_OP(mo) \ -static inline long atomic_long_read##mo(atomic_long_t *l) \ +static inline long atomic_long_read##mo(const atomic_long_t *l) \ { \ ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \ \ @@ -43,6 +43,7 @@ static inline long atomic_long_read##mo(atomic_long_t *l) \ } ATOMIC_LONG_READ_OP() ATOMIC_LONG_READ_OP(_acquire) +ATOMIC_LONG_READ_OP(_ctrl) #undef ATOMIC_LONG_READ_OP -- cgit v1.2.3