From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 6 Mar 2008 21:14:26 -0800 (PST) From: David Rientjes Subject: Re: [PATCH] Add cgroup support for enabling controllers at boot time In-Reply-To: <47D0C76D.8050207@linux.vnet.ibm.com> Message-ID: References: <20080306185952.23290.49571.sendpatchset@localhost.localdomain> <47D0C76D.8050207@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Balbir Singh Cc: Paul Menage , Andrew Morton , Pavel Emelianov , Hugh Dickins , Sudhir Kumar , YAMAMOTO Takashi , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, KAMEZAWA Hiroyuki List-ID: On Fri, 7 Mar 2008, Balbir Singh wrote: > >> +static int __init cgroup_disable(char *str) > >> +{ > >> + int i; > >> + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { > >> + struct cgroup_subsys *ss = subsys[i]; > >> + if (!strcmp(str, ss->name)) { > >> + ss->disabled = 1; > >> + break; > >> + } > >> + } > >> +} > >> +__setup("cgroup_disable=", cgroup_disable); > > > > This doesn't handle spaces very well, so isn't it possible for the name of > > a current or future cgroup subsystem to be specified after cgroup_disable= > > on the command line and have it disabled by accident? > > > > How do you distinguish that from the user wanting to disable the controller on > purpose? My understanding is that after parsing cgroup_disable=, the rest of the > text is passed to cgroup_disable to process further. You'll find that all the > __setup() code in the kernel is implemented this way. > Since the command line is logically delimited by spaces, you can accidently disable a subsystem if its name appears in any of your kernel options following your cgroup_disable= option. So if you're absolutely confident that it wouldn't happen (for instance, if there's no logical reason that a cgroup subsystem name should appear anywhere besides cgroup_disable on the command line), then there's no objection. -- 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/ . Don't email: email@kvack.org