From acdc9fc9a8121ce2ebcd7533bd72852c20b353f3 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 20 Aug 2015 12:57:33 +0200 Subject: [PATCH] s390/bitops: implement cache friendly test_and_set_bit_lock The generic implementation for test_and_set_bit_lock in include/asm-generic uses the standard test_and_set_bit operation. This is done with either a 'csg' or a 'loag' instruction. For both version the cache line is fetched exclusively, even if the bit is already set. The result is an increase in cache traffic, for a contented lock this is a bad idea. Acked-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/bitops.h | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h index 9b68e98a724f..66a1cff67353 100644 --- a/arch/s390/include/asm/bitops.h +++ b/arch/s390/include/asm/bitops.h @@ -276,6 +276,28 @@ static inline int test_bit(unsigned long nr, const volatile unsigned long *ptr) return (*addr >> (nr & 7)) & 1; } +static inline int test_and_set_bit_lock(unsigned long nr, + volatile unsigned long *ptr) +{ + if (test_bit(nr, ptr)) + return 1; + return test_and_set_bit(nr, ptr); +} + +static inline void clear_bit_unlock(unsigned long nr, + volatile unsigned long *ptr) +{ + smp_mb__before_atomic(); + clear_bit(nr, ptr); +} + +static inline void __clear_bit_unlock(unsigned long nr, + volatile unsigned long *ptr) +{ + smp_mb(); + __clear_bit(nr, ptr); +} + /* * Functions which use MSB0 bit numbering. * On an s390x system the bits are numbered: @@ -446,7 +468,6 @@ static inline int fls(int word) #include #include #include -#include #include #include #include -- 2.30.2