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cgroup: grab cgroup_mutex earlier in cgroup_subtree_control_write()

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Move cgroup_lock_live_group() invocation upwards to right below
cgroup_tree_mutex in cgroup_subtree_control_write().  This is to help
the planned locking simplification.

This doesn't make any userland-visible behavioral changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2014-05-13 12:19:22 -04:00
parent b3bfd983ca
commit ddab2b6e0e
1 changed files with 8 additions and 8 deletions
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16
kernel/cgroup.c
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@ -2583,6 +2583,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
kernfs_break_active_protection(of->kn);
mutex_lock(&cgroup_tree_mutex);
if (!cgroup_lock_live_group(cgrp)) {
ret = -ENODEV;
goto out_unlock_tree;
}
for_each_subsys(ss, ssid) {
if (enable & (1 << ssid)) {
@ -2606,6 +2610,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
cgroup_get(child);
prepare_to_wait(&child->offline_waitq, &wait,
TASK_UNINTERRUPTIBLE);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&cgroup_tree_mutex);
schedule();
finish_wait(&child->offline_waitq, &wait);
@ -2620,7 +2625,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
(cgrp->parent &&
!(cgrp->parent->child_subsys_mask & (1 << ssid)))) {
ret = -ENOENT;
goto out_unlock_tree;
goto out_unlock;
}
} else if (disable & (1 << ssid)) {
if (!(cgrp->child_subsys_mask & (1 << ssid))) {
@ -2632,7 +2637,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
cgroup_for_each_live_child(child, cgrp) {
if (child->child_subsys_mask & (1 << ssid)) {
ret = -EBUSY;
goto out_unlock_tree;
goto out_unlock;
}
}
}
@ -2640,12 +2645,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
if (!enable && !disable) {
ret = 0;
goto out_unlock_tree;
}
if (!cgroup_lock_live_group(cgrp)) {
ret = -ENODEV;
goto out_unlock_tree;
goto out_unlock;
}
/*