From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757228AbaEFLuz (ORCPT ); Tue, 6 May 2014 07:50:55 -0400 Received: from mail-qg0-f43.google.com ([209.85.192.43]:32855 "EHLO mail-qg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841AbaEFLuu (ORCPT ); Tue, 6 May 2014 07:50:50 -0400 From: Tejun Heo To: lizefan@huawei.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 3/4] cgroup: use restart_syscall() for retries after offline waits in cgroup_subtree_control_write() Date: Tue, 6 May 2014 07:50:43 -0400 Message-Id: <1399377044-29873-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1399377044-29873-1-git-send-email-tj@kernel.org> References: <1399377044-29873-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After waiting for a child to finish offline, cgroup_subtree_control_write() jumps up to retry from after the input parsing and active protection breaking. This retry makes the scheduled locking update more difficult. Let's simplify it by returning with restart_syscall() for retries. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 9066fe9..3ced79a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2535,7 +2535,7 @@ out_finish: static int cgroup_subtree_control_write(struct cgroup_subsys_state *dummy_css, struct cftype *cft, char *buffer) { - unsigned int enable_req = 0, disable_req = 0, enable, disable; + unsigned int enable = 0, disable = 0; struct cgroup *cgrp = dummy_css->cgroup, *child; struct cgroup_subsys *ss; char *tok, *p; @@ -2552,11 +2552,11 @@ static int cgroup_subtree_control_write(struct cgroup_subsys_state *dummy_css, continue; if (*tok == '+') { - enable_req |= 1 << ssid; - disable_req &= ~(1 << ssid); + enable |= 1 << ssid; + disable &= ~(1 << ssid); } else if (*tok == '-') { - disable_req |= 1 << ssid; - enable_req &= ~(1 << ssid); + disable |= 1 << ssid; + enable &= ~(1 << ssid); } else { return -EINVAL; } @@ -2574,9 +2574,6 @@ static int cgroup_subtree_control_write(struct cgroup_subsys_state *dummy_css, */ cgroup_get(cgrp); kernfs_break_active_protection(cgrp->control_kn); -retry: - enable = enable_req; - disable = disable_req; mutex_lock(&cgroup_tree_mutex); @@ -2606,7 +2603,9 @@ retry: schedule(); finish_wait(&child->offline_waitq, &wait); cgroup_put(child); - goto retry; + + ret = restart_syscall(); + goto out_unbreak; } /* unavailable or not enabled on the parent? */ @@ -2690,6 +2689,7 @@ out_unlock: mutex_unlock(&cgroup_mutex); out_unlock_tree: mutex_unlock(&cgroup_tree_mutex); +out_unbreak: kernfs_unbreak_active_protection(cgrp->control_kn); cgroup_put(cgrp); return ret; -- 1.9.0