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s390/locking: Reenable optimistic spinning

commit 4badad352a6bb202ec68afa7a574c0bb961e5ebc (locking/mutex: Disable
optimistic spinning on some architectures) fenced spinning for
architectures without proper cmpxchg.
There is no need to disable mutex spinning on s390, though:
The instructions CS,CSG and friends provide the proper guarantees.
(We dont implement cmpxchg with locks).

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Christian Borntraeger 11 years ago
parent
152125b7a8
commit
36e7fdaa1a
1 changed files with 1 additions and 0 deletions
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  1. 1 0
      arch/s390/Kconfig

+ 1 - 0
arch/s390/Kconfig
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@@ -92,6 +92,7 @@ config S390
 
 	select ARCH_INLINE_WRITE_UNLOCK_IRQ
 
 	select ARCH_INLINE_WRITE_UNLOCK_IRQ
 
 	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 
 	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 
 	select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 
 	select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 
+	select ARCH_SUPPORTS_ATOMIC_RMW
 
 	select ARCH_USE_CMPXCHG_LOCKREF
 
 	select ARCH_USE_CMPXCHG_LOCKREF
 
 	select ARCH_WANT_IPC_PARSE_VERSION
 
 	select ARCH_WANT_IPC_PARSE_VERSION
 
 	select BUILDTIME_EXTABLE_SORT
 
 	select BUILDTIME_EXTABLE_SORT