Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754958Ab1DVKyV (ORCPT ); Fri, 22 Apr 2011 06:54:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60095 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754682Ab1DVKyU (ORCPT ); Fri, 22 Apr 2011 06:54:20 -0400 From: Xiaotian feng To: linux-kernel@vger.kernel.org Cc: Xiaotian Feng , Ingo Molnar , Peter Zijlstra Subject: [PATCH -tip v2] sched: more sched_domain iterations fix Date: Fri, 22 Apr 2011 18:53:54 +0800 Message-Id: <1303469634-11678-1-git-send-email-dfeng@redhat.com> In-Reply-To: <1303384893.2035.73.camel@laptop> References: <1303384893.2035.73.camel@laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2547 Lines: 82 From: Xiaotian Feng sched_domain iterations needs to be protected by rcu_read_lock() now, this patch adds another two places which needs the rcu lock, which is spotted by following suspicious rcu_dereference_check() usage warnings. kernel/sched_rt.c:1244 invoked rcu_dereference_check() without protection! kernel/sched_stats.h:41 invoked rcu_dereference_check() without protection! Signed-off-by: Xiaotian Feng Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/sched_rt.c | 10 ++++++++-- kernel/sched_stats.h | 4 ++-- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 19ecb31..46a9533 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1241,6 +1241,7 @@ static int find_lowest_rq(struct task_struct *task) if (!cpumask_test_cpu(this_cpu, lowest_mask)) this_cpu = -1; /* Skip this_cpu opt if not among lowest */ + rcu_read_lock(); for_each_domain(cpu, sd) { if (sd->flags & SD_WAKE_AFFINE) { int best_cpu; @@ -1250,15 +1251,20 @@ static int find_lowest_rq(struct task_struct *task) * remote processor. */ if (this_cpu != -1 && - cpumask_test_cpu(this_cpu, sched_domain_span(sd))) + cpumask_test_cpu(this_cpu, sched_domain_span(sd))) { + rcu_read_unlock(); return this_cpu; + } best_cpu = cpumask_first_and(lowest_mask, sched_domain_span(sd)); - if (best_cpu < nr_cpu_ids) + if (best_cpu < nr_cpu_ids) { + rcu_read_unlock(); return best_cpu; + } } } + rcu_read_unlock(); /* * And finally, if there were no matches within the domains diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h index 48ddf43..331e01b 100644 --- a/kernel/sched_stats.h +++ b/kernel/sched_stats.h @@ -37,7 +37,7 @@ static int show_schedstat(struct seq_file *seq, void *v) #ifdef CONFIG_SMP /* domain-specific stats */ - preempt_disable(); + rcu_read_lock(); for_each_domain(cpu, sd) { enum cpu_idle_type itype; @@ -64,7 +64,7 @@ static int show_schedstat(struct seq_file *seq, void *v) sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance); } - preempt_enable(); + rcu_read_unlock(); #endif } kfree(mask_str); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/