From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266Ab1ISJKJ (ORCPT ); Mon, 19 Sep 2011 05:10:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25364 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751896Ab1ISJKH (ORCPT ); Mon, 19 Sep 2011 05:10:07 -0400 Date: Mon, 19 Sep 2011 11:09:27 +0200 (CEST) From: John Kacur X-X-Sender: jkacur@localhost6.localdomain6 To: Thomas Gleixner , linux-rt-users@vger.kernel.org cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: =?ISO-8859-7?Q?=5BPATCH=5D_preempt-rt=3A_VERSION_2=3A_Fix_build_error=3A_section_of_=A1tasklist=5Flock=A2_conflicts?= Message-ID: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-1475679927-1124203029-1316423373=:23118" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1475679927-1124203029-1316423373=:23118 Content-Type: TEXT/PLAIN; charset=ISO-8859-7 Content-Transfer-Encoding: 8BIT >>From 60b91dea371067c529587c504be0543350d1c0e5 Mon Sep 17 00:00:00 2001 From: John Kacur Date: Mon, 19 Sep 2011 10:29:42 +0200 Subject: [PATCH] =?UTF-8?q?preempt-rt:=20VERSION=202:=20Fix=20build=20error:=20section=20of=20=E2=80=98tasklist=5Flock=E2=80=99=20conflicts=20with=20previous=20declaration?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This fixes the following build error for the preempt-rt kernel. make kernel/fork.o CC kernel/fork.o kernel/fork.c:90: error: section of Ątasklist_locką conflicts with previous declaration make[2]: *** [kernel/fork.o] Error 1 make[1]: *** [kernel/fork.o] Error 2 The rt kernel cache aligns the RWLOCK in DEFINE_RWLOCK by default. The non-rt kernels explicitly cache align only the tasklist_lock in kernel/fork.c That can create a build conflict. This fixes the build problem by making the non-rt kernels cache align RWLOCKs by default. The side effect is that the other RWLOCKs are also cache aligned for non-rt. This is a short term solution for rt only. The longer term solution would be to push the cache aligned DEFINE_RWLOCK to mainline. If there are objections, then we could create a DEFINE_RWLOCK_CACHE_ALIGNED or something of that nature. Comments? Objections? Signed-off-by: John Kacur --- include/linux/rwlock_types.h | 3 ++- kernel/fork.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/rwlock_types.h b/include/linux/rwlock_types.h index 5317cd9..d0da966 100644 --- a/include/linux/rwlock_types.h +++ b/include/linux/rwlock_types.h @@ -47,6 +47,7 @@ typedef struct { RW_DEP_MAP_INIT(lockname) } #endif -#define DEFINE_RWLOCK(x) rwlock_t x = __RW_LOCK_UNLOCKED(x) +#define DEFINE_RWLOCK(name) \ + rwlock_t name __cacheline_aligned_in_smp = __RW_LOCK_UNLOCKED(name) #endif /* __LINUX_RWLOCK_TYPES_H */ diff --git a/kernel/fork.c b/kernel/fork.c index aa5fe26..8487ae7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -87,7 +87,7 @@ int max_threads; /* tunable limit on nr_threads */ DEFINE_PER_CPU(unsigned long, process_counts) = 0; -__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ +DEFINE_RWLOCK(tasklist_lock); /* outer */ #ifdef CONFIG_PROVE_RCU int lockdep_tasklist_lock_is_held(void) -- 1.7.2.3 ---1475679927-1124203029-1316423373=:23118--