From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 5/7] cgroup: use restart_syscall() for retries after offline waits in cgroup_subtree_control_write() Date: Fri, 9 May 2014 15:32:53 -0400 Message-ID: <1399663975-315-6-git-send-email-tj@kernel.org> References: <1399663975-315-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=j0Ks298ZnN0m6zC2ZwtfOQykmads7f2kMhA09dgMvNc=; b=uiAa77aalZ1LVi6ZKxMuRVNzMpQdP/FE+YlwG5n+wezhnDOb+fAGyLkBIC/X3Twpdm IqupOZJMk45eq4zE3VL+VdCJPXuk6aX1eX4BvnaeSh291N3xByClp9iN+THKJ0cpBpGc yXs5fQLdDoupp0xf7zYP+BdOYC8CYY+QrukKdfr5Arc3gi8qYmOPg/qFXaEWbXoTuuMY 6HpbMNIVw/xYMvjAD2YmdRkTvVGFHcaRyp+jHSbyUdKqO+7It03VbK31KOWHoZ/54WLw VitkvwZleBYRDxMRqlA73DRW+3WrSEQSqoLJq+FD/mf1rhIqE4zQ5YYEUjCXzNtGipQV bHHw== In-Reply-To: <1399663975-315-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lizefan@huawei.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo 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 b81e7c0..ff92bac 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; @@ -2554,11 +2554,11 @@ 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; } @@ -2576,9 +2576,6 @@ 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); @@ -2608,7 +2605,9 @@ 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? */ @@ -2692,6 +2691,7 @@ 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