Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754786AbYFRVOV (ORCPT ); Wed, 18 Jun 2008 17:14:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753667AbYFRVOM (ORCPT ); Wed, 18 Jun 2008 17:14:12 -0400 Received: from smtp-out.google.com ([216.239.33.17]:63348 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632AbYFRVOK (ORCPT ); Wed, 18 Jun 2008 17:14:10 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=tr9GAw+B7dvosJtnhJpGqOWsBBcPAD1f25Ootxyj5SZc0jFpAE1BGHcIfZTRfyuZL Ncxfh6nivaCpoibzqLtbw== Message-ID: <6599ad830806181413y5d0ef1bfyfc54c17ee904d744@mail.gmail.com> Date: Wed, 18 Jun 2008 14:13:58 -0700 From: "Paul Menage" To: "Li Zefan" Subject: Re: [PATCH] cgroup: support checking of subsystem dependencies Cc: "Andrew Morton" , LKML , "containers@lists.osdl.org" , "Balbir Singh" , "KAMEZAWA Hiroyuki" , "Paul Jackson" In-Reply-To: <4858C0ED.2080905@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4858C0ED.2080905@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3438 Lines: 94 On Wed, Jun 18, 2008 at 1:01 AM, Li Zefan wrote: > This allows one subsystem to require that it only be mounted when some > other subsystems are also present in the proposed hierarchy. > > For example if subsystem foo depends on bar, the following will fail: > # mount -t cgroup -ofoo xxx /dev/cgroup > > You should mount with both subsystems: > # mount -t cgroup -ofoo,bar xxx /dev/cgroup > > Signed-off-by: Li Zefan > --- > Documentation/cgroups.txt | 6 ++++++ > include/linux/cgroup.h | 2 ++ > kernel/cgroup.c | 30 ++++++++++++++++++++++++++++++ > 3 files changed, 38 insertions(+), 0 deletions(-) > > diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt > index 824fc02..8252f5b 100644 > --- a/Documentation/cgroups.txt > +++ b/Documentation/cgroups.txt > @@ -530,6 +530,12 @@ and root cgroup. Currently this will only involve movement between > the default hierarchy (which never has sub-cgroups) and a hierarchy > that is being created/destroyed (and hence has no sub-cgroups). > > +int subsys_depend(struct cgroup_subsys *ss, unsigned long subsys_bits) > + > +Called when a cgroup subsystem wants to check if some other subsystems > +are also present in the proposed hierarchy. If this method returns error, > +the mount of the cgroup filesystem will fail. > + > 4. Questions > ============ > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index e155aa7..fc99ba4 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -305,6 +305,8 @@ struct cgroup_subsys { > struct cgroup *cgrp); > void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); > void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); > + int (*subsys_depend)(struct cgroup_subsys *ss, > + unsigned long subsys_bits); > /* > * This routine is called with the task_lock of mm->owner held > */ > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 15ac0e1..a4c8671 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -837,6 +837,25 @@ static int parse_cgroupfs_options(char *data, > return 0; > } > > +static int check_subsys_dependency(unsigned long subsys_bits) > +{ > + int i; > + int ret; > + struct cgroup_subsys *ss; > + > + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { > + ss = subsys[i]; > + > + if (test_bit(i, &subsys_bits) && ss->subsys_depend) { > + ret = ss->subsys_depend(ss, subsys_bits); > + if (ret) > + return ret; > + } > + } > + > + return 0; > +} > + > static int cgroup_remount(struct super_block *sb, int *flags, char *data) > { > int ret = 0; > @@ -852,6 +871,10 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) > if (ret) > goto out_unlock; > > + ret = check_subsys_dependency(opts.subsys_bits); > + if (ret) > + goto out_unlock; > + Can we just call this from one place, in parse_cgroupfs_options() ? Paul -- 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/