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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2015-09-28 15:27:26 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-10-14 14:32:07 +0200
commit5da7667c035f3a711ec8d0a3997254807dd8bc6d (patch)
tree5fa860d7cbf09ccc0d3096d5986867b5bfc6b86f /arch/s390/include/asm/bitops.h
parentb5a6b71b1901b9ca495f669c9ad86f2181960aba (diff)
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 <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/bitops.h')
-rw-r--r--arch/s390/include/asm/bitops.h1
1 files changed, 0 insertions, 1 deletions
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)) \