This is a note to let you know that I've just added the patch titled
s390/locking: Reenable optimistic spinning
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-locking-reenable-optimistic-spinning.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 36e7fdaa1a04fcf65b864232e1af56a51c7814d6 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Date: Tue, 5 Aug 2014 09:57:51 +0200
Subject: s390/locking: Reenable optimistic spinning
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/Kconfig | 1 +
1 file changed, 1 insertion(+)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -92,6 +92,7 @@ config S390
select ARCH_INLINE_WRITE_UNLOCK_IRQ
select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
select ARCH_SAVE_PAGE_KEYS if HIBERNATION
+ select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
Patches currently in stable-queue which might be from borntraeger@xxxxxxxxxx are
queue-3.16/s390-locking-reenable-optimistic-spinning.patch
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