From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christian Borntraeger , Ingo Molnar , Peter Zijlstra , Heiko Carstens , Martin Schwidefsky Subject: [PATCH 3.16 017/158] s390/locking: Reenable optimistic spinning Date: Mon, 15 Sep 2014 12:24:16 -0700 Message-Id: <20140915192543.396076802@linuxfoundation.org> In-Reply-To: <20140915192542.872134685@linuxfoundation.org> References: <20140915192542.872134685@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Borntraeger 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 Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- 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