From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760693AbYHOQp2 (ORCPT ); Fri, 15 Aug 2008 12:45:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755089AbYHOQpP (ORCPT ); Fri, 15 Aug 2008 12:45:15 -0400 Received: from tomts10.bellnexxia.net ([209.226.175.54]:63416 "EHLO tomts10-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754436AbYHOQpN (ORCPT ); Fri, 15 Aug 2008 12:45:13 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AuYEAMxJpUhMRKxB/2dsb2JhbACBYrIlgVc Date: Fri, 15 Aug 2008 12:45:09 -0400 From: Mathieu Desnoyers To: Linus Torvalds Cc: Ingo Molnar , Jeremy Fitzhardinge , Harvey Harrison , Andi Kleen , Steven Rostedt , Steven Rostedt , LKML , Thomas Gleixner , Peter Zijlstra , Andrew Morton , David Miller , Roland McGrath , Ulrich Drepper , Rusty Russell , Gregory Haskins , Arnaldo Carvalho de Melo , "Luis Claudio R. Goncalves" , Clark Williams , Christoph Lameter , "H. Peter Anvin" Subject: [PATCH] x86 : revert replace LOCK_PREFIX in futex.h Message-ID: <20080815164509.GC21138@Krystal> References: <20080814205815.GA14076@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 12:37:56 up 71 days, 21:18, 6 users, load average: 0.91, 0.78, 0.83 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Depends on : x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug On Thu, 14 Aug 2008, Mathieu Desnoyers wrote: > > Changing the 0x90 (single-byte nop) currently used into a 0x3E DS segment > override prefix should fix this issue. Since the default of the atomic > instructions is to use the DS segment anyway, it should not affect the > behavior. Ok, so I think this is an _excellent_ patch, but I'd like to also then use LOCK_PREFIX in include/asm-x86/futex.h. See commit 9d55b9923a1b7ea8193b8875c57ec940dc2ff027. Linus Applies to 2.6.27-rc2 (and -rc3 unless hell broke loose in futex.h between rc2 and rc3). Signed-off-by: Mathieu Desnoyers CC: Linus Torvalds CC: H. Peter Anvin CC: Jeremy Fitzhardinge CC: Roland McGrath CC: Ingo Molnar Cc: Steven Rostedt CC: Steven Rostedt CC: Thomas Gleixner CC: Peter Zijlstra CC: Andrew Morton CC: David Miller CC: Ulrich Drepper CC: Rusty Russell CC: Gregory Haskins CC: Arnaldo Carvalho de Melo CC: "Luis Claudio R. Goncalves" CC: Clark Williams CC: Christoph Lameter CC: Andi Kleen CC: Harvey Harrison --- include/asm-x86/futex.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-2.6-lttng/include/asm-x86/futex.h =================================================================== --- linux-2.6-lttng.orig/include/asm-x86/futex.h 2008-08-15 12:32:38.000000000 -0400 +++ linux-2.6-lttng/include/asm-x86/futex.h 2008-08-15 12:41:33.000000000 -0400 @@ -25,7 +25,7 @@ asm volatile("1:\tmovl %2, %0\n" \ "\tmovl\t%0, %3\n" \ "\t" insn "\n" \ - "2:\tlock; cmpxchgl %3, %2\n" \ + "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \ "\tjnz\t1b\n" \ "3:\t.section .fixup,\"ax\"\n" \ "4:\tmov\t%5, %1\n" \ @@ -64,7 +64,7 @@ static inline int futex_atomic_op_inuser __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op1("lock; xaddl %0, %2", ret, oldval, + __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_OR: @@ -122,7 +122,7 @@ static inline int futex_atomic_cmpxchg_i if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - asm volatile("1:\tlock; cmpxchgl %3, %1\n" + asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n" "2:\t.section .fixup, \"ax\"\n" "3:\tmov %2, %0\n" "\tjmp 2b\n" -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68