As per the existing implementation; implement the new one using
smp_mb().
AFAICT the s390 compare-and-swap does imply a barrier, however there
are some immediate ops that seem to be singly-copy atomic and do not
imply a barrier. One such is the "ni" op (which would be
and-immediate) which is used for the constant clear_bit
implementation. Therefore s390 needs full barriers for the
{before,after} atomic ops.
Signed-off-by: Peter Zijlstra <pet...@infradead.org>
---
arch/s390/include/asm/atomic.h | 6 +-----
arch/s390/include/asm/barrier.h | 5 +++--
arch/s390/include/asm/bitops.h | 1 +
3 files changed, 5 insertions(+), 7 deletions(-)
--- a/arch/s390/include/asm/atomic.h
+++ b/arch/s390/include/asm/atomic.h
@@ -16,6 +16,7 @@
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/cmpxchg.h>
+#include <asm/barrier.h>
#define ATOMIC_INIT(i) { (i) }
@@ -398,9 +399,4 @@ static inline long long atomic64_dec_if_
#define atomic64_dec_and_test(_v) (atomic64_sub_return(1, _v) == 0)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
-#define smp_mb__before_atomic_dec() smp_mb()
-#define smp_mb__after_atomic_dec() smp_mb()
-#define smp_mb__before_atomic_inc() smp_mb()
-#define smp_mb__after_atomic_inc() smp_mb()
-
#endif /* __ARCH_S390_ATOMIC__ */
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -27,8 +27,9 @@
#define smp_rmb() rmb()
#define smp_wmb() wmb()
#define smp_read_barrier_depends() read_barrier_depends()
-#define smp_mb__before_clear_bit() smp_mb()
-#define smp_mb__after_clear_bit() smp_mb()
+
+#define smp_mb__before_atomic() smp_mb()
+#define smp_mb__after_atomic() smp_mb()
#define set_mb(var, value) do { var = value; mb(); } while (0)
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -47,6 +47,7 @@
#include <linux/typecheck.h>
#include <linux/compiler.h>
+#include <asm/barrier.h>
#ifndef CONFIG_64BIT
--
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