| From | Ben Hutchings <> | Date | Thu, 11 Sep 2014 13:32:13 +0100 | Subject | [PATCH 3.2 057/131] s390/locking: Reenable optimistic spinning |
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3.2.63-rc1 review patch. If anyone has any objections, please let me know.
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From: Christian Borntraeger <borntraeger@de.ibm.com>
commit 36e7fdaa1a04fcf65b864232e1af56a51c7814d6 upstream.
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> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/s390/Kconfig | 1 + 1 file changed, 1 insertion(+)
--- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -119,6 +119,7 @@ config S390 select ARCH_INLINE_WRITE_UNLOCK_BH select ARCH_INLINE_WRITE_UNLOCK_IRQ select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE + select ARCH_SUPPORTS_ATOMIC_RMW config SCHED_OMIT_FRAME_POINTER def_bool y
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