From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755567AbaENNMx (ORCPT ); Wed, 14 May 2014 09:12:53 -0400 Received: from mail-qc0-f172.google.com ([209.85.216.172]:61142 "EHLO mail-qc0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755398AbaENNMv (ORCPT ); Wed, 14 May 2014 09:12:51 -0400 Date: Wed, 14 May 2014 09:12:48 -0400 From: Tejun Heo To: lizefan@huawei.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/9] cgroup: use restart_syscall() for mount retries Message-ID: <20140514131248.GF28815@htj.dyndns.org> References: <1399670015-23463-1-git-send-email-tj@kernel.org> <1399670015-23463-2-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1399670015-23463-2-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cgroup_mount() uses dumb delay-and-retry logic to wait for cgroup_root which is being destroyed. The retry currently loops inside cgroup_mount() proper. This patch makes it return with restart_syscall() instead so that retry travels out to userland boundary. This slightly simplifies the logic and more importantly makes the retry logic behave better when the wait for some reason becomes lengthy or infinite by allowing the operation to be suspended or terminated from userland. v2: The original patch forgot to free memory allocated for @opts. Fixed. Caught by Li Zefan. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1681,7 +1681,7 @@ static struct dentry *cgroup_mount(struc ret = parse_cgroupfs_options(data, &opts); if (ret) goto out_unlock; -retry: + /* look for a matching existing root */ if (!opts.subsys_mask && !opts.none && !opts.name) { cgrp_dfl_root_visible = true; @@ -1740,8 +1740,8 @@ retry: if (!atomic_inc_not_zero(&root->cgrp.refcnt)) { mutex_unlock(&cgroup_mutex); msleep(10); - mutex_lock(&cgroup_mutex); - goto retry; + ret = restart_syscall(); + goto out_free; } ret = 0; @@ -1772,7 +1772,7 @@ retry: out_unlock: mutex_unlock(&cgroup_mutex); - +out_free: kfree(opts.release_agent); kfree(opts.name);