From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id E7C2F8D0039 for ; Mon, 28 Feb 2011 18:56:10 -0500 (EST) Date: Mon, 28 Feb 2011 15:55:24 -0800 From: Andrew Morton Subject: Re: [PATCH] cpuset: Add a missing unlock in cpuset_write_resmask() Message-Id: <20110228155524.6d7563e0.akpm@linux-foundation.org> In-Reply-To: <4D6601B2.1090207@cn.fujitsu.com> References: <4D6601B2.1090207@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Li Zefan Cc: Paul Menage , David Rientjes , =?UTF-8?Q?=E7=BC=AA_=E5=8B=B0?= , LKML , linux-mm@kvack.org On Thu, 24 Feb 2011 14:58:58 +0800 Li Zefan wrote: > Don't forget to release cgroup_mutex if alloc_trial_cpuset() fails. > > Signed-off-by: Li Zefan > --- > kernel/cpuset.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/kernel/cpuset.c b/kernel/cpuset.c > index 1ca786a..6272503 100644 > --- a/kernel/cpuset.c > +++ b/kernel/cpuset.c > @@ -1561,8 +1561,10 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft, > return -ENODEV; > > trialcs = alloc_trial_cpuset(cs); > - if (!trialcs) > + if (!trialcs) { > + cgroup_unlock(); > return -ENOMEM; > + } > > switch (cft->private) { > case FILE_CPULIST: It would be better to avoid multiple returns - it leads to more maintainable code and often shorter code: --- a/kernel/cpuset.c~cpuset-add-a-missing-unlock-in-cpuset_write_resmask-fix +++ a/kernel/cpuset.c @@ -1562,8 +1562,8 @@ static int cpuset_write_resmask(struct c trialcs = alloc_trial_cpuset(cs); if (!trialcs) { - cgroup_unlock(); - return -ENOMEM; + retval = -ENOMEM; + goto out; } switch (cft->private) { @@ -1579,6 +1579,7 @@ static int cpuset_write_resmask(struct c } free_trial_cpuset(trialcs); +out: cgroup_unlock(); return retval; } _ also, alloc_trial_cpuset() is a fairly slow-looking function. cpuset_write_resmask() could run alloc_trial_cpuset() before running cgroup_lock_live_group(), thereby reducing lock hold times. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org