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[v3,41/41] s390: more efficient smp barriers

Message ID 1452426622-4471-42-git-send-email-mst@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Michael S. Tsirkin Jan. 10, 2016, 2:22 p.m. UTC 
As per: lkml.kernel.org/r/20150921112252.3c2937e1@mschwide
atomics imply a barrier on s390, so s390 should change
smp_mb__before_atomic and smp_mb__after_atomic to barrier() instead of
smp_mb() and hence should not use the generic versions.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 arch/s390/include/asm/barrier.h | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index 4d26fa4..5c8db3c 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -45,6 +45,9 @@  do {									\
 	___p1;								\
 })
 
+#define __smp_mb__before_atomic()	barrier()
+#define __smp_mb__after_atomic()	barrier()
+
 #include <asm-generic/barrier.h>
 
 #endif /* __ASM_BARRIER_H */