From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbaGWROw (ORCPT ); Wed, 23 Jul 2014 13:14:52 -0400 Received: from mail-la0-f47.google.com ([209.85.215.47]:53233 "EHLO mail-la0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932201AbaGWROv (ORCPT ); Wed, 23 Jul 2014 13:14:51 -0400 MIME-Version: 1.0 In-Reply-To: <20140723120654.GF11241@linux.vnet.ibm.com> References: <1406092194-13004-1-git-send-email-bobby.prani@gmail.com> <1406092194-13004-3-git-send-email-bobby.prani@gmail.com> <20140723120654.GF11241@linux.vnet.ibm.com> From: Pranith Kumar Date: Wed, 23 Jul 2014 13:14:19 -0400 Message-ID: Subject: Re: [PATCH 02/16] rcu: Check return value for cpumask allocation To: Paul McKenney Cc: Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , "open list:READ-COPY UPDATE..." Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 23, 2014 at 8:06 AM, Paul E. McKenney wrote: >> --- a/kernel/rcu/tree_plugin.h >> +++ b/kernel/rcu/tree_plugin.h >> @@ -88,7 +88,10 @@ static void __init rcu_bootup_announce_oddness(void) >> #ifdef CONFIG_RCU_NOCB_CPU >> #ifndef CONFIG_RCU_NOCB_CPU_NONE >> if (!have_rcu_nocb_mask) { >> - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL); >> + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) { >> + pr_info("rcu_nocb_mask allocation failed\n"); >> + return; > > Good catch, but this "return" is an accident waiting to happen. The > accident will happen as soon as another RCU option appears, and the > person adding it quite naturally adds it at the end of this function. > The cleanest approach is to make an rcu_bootup_announce_oddness_nocb() > as one commit that does -only- code motion, and the make this change > as another commit. > Hi Paul, Looking at this, I think the following is simpler without having to introduce a new function. What do you think? diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c31eb28..f2ed342 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -88,8 +88,10 @@ static void __init rcu_bootup_announce_oddness(void) #ifdef CONFIG_RCU_NOCB_CPU #ifndef CONFIG_RCU_NOCB_CPU_NONE if (!have_rcu_nocb_mask) { - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL); - have_rcu_nocb_mask = true; + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) + pr_info("rcu_nocb_mask allocation failed"); + else + have_rcu_nocb_mask = true; } #ifdef CONFIG_RCU_NOCB_CPU_ZERO pr_info("\tOffload RCU callbacks from CPU 0\n"); -- Pranith