From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754564AbaIKNE2 (ORCPT ); Thu, 11 Sep 2014 09:04:28 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52280 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753980AbaIKNEW (ORCPT ); Thu, 11 Sep 2014 09:04:22 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Heiko Carstens" , "Peter Zijlstra" , "Christian Borntraeger" , "Martin Schwidefsky" , "Ingo Molnar" Date: Thu, 11 Sep 2014 13:32:13 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 057/131] s390/locking: Reenable optimistic spinning In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.63-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- 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