From: Martin Schwidefsky Date: Mon, 28 Sep 2015 13:27:26 +0000 (+0200) Subject: s390/barrier: remove unnecessary serialization in atomics and bitops X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=5da7667c035f3a711ec8d0a3997254807dd8bc6d;p=linux-beck.git s390/barrier: remove unnecessary serialization in atomics and bitops The principles of operation states reads are in order, writes are in order, writes can be reordered after reads, but no reads can be reordered after writes. The atomic and bitops variantes for z196 use the interlocked-access facility instructions with a memory barrier before and after the instruction. Because of the memory ordering the first barrier is unnecessary and can be removed. Acked-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/include/asm/atomic.h b/arch/s390/include/asm/atomic.h index 117fa5c921c1..911064aa59b2 100644 --- a/arch/s390/include/asm/atomic.h +++ b/arch/s390/include/asm/atomic.h @@ -36,7 +36,6 @@ \ typecheck(atomic_t *, ptr); \ asm volatile( \ - __barrier \ op_string " %0,%2,%1\n" \ __barrier \ : "=d" (old_val), "+Q" ((ptr)->counter) \ @@ -180,7 +179,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u) \ typecheck(atomic64_t *, ptr); \ asm volatile( \ - __barrier \ op_string " %0,%2,%1\n" \ __barrier \ : "=d" (old_val), "+Q" ((ptr)->counter) \ diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h index 66a1cff67353..47bd0878a006 100644 --- a/arch/s390/include/asm/bitops.h +++ b/arch/s390/include/asm/bitops.h @@ -64,7 +64,6 @@ \ typecheck(unsigned long *, (__addr)); \ asm volatile( \ - __barrier \ __op_string " %0,%2,%1\n" \ __barrier \ : "=d" (__old), "+Q" (*(__addr)) \