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cgroup: reorganize cgroup_subtree_control_write()

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Make the following two reorganizations to
cgroup_subtree_control_write().  These are to prepare for future
changes and shouldn't cause any functional difference.

* Move availability above css offlining wait.

* Move cgrp->child_subsys_mask update above new css creation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
This commit is contained in:
Tejun Heo 2014-07-08 18:02:56 -04:00
parent a497c3ba1d
commit c29adf24e0
1 changed files with 17 additions and 17 deletions
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34
kernel/cgroup.c
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@ -2613,6 +2613,14 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
continue;
}
/* unavailable or not enabled on the parent? */
if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
(cgroup_parent(cgrp) &&
!(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {
ret = -ENOENT;
goto out_unlock;
}
/*
* Because css offlining is asynchronous, userland
* might try to re-enable the same controller while
@ -2635,14 +2643,6 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
return restart_syscall();
}
/* unavailable or not enabled on the parent? */
if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
(cgroup_parent(cgrp) &&
!(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {
ret = -ENOENT;
goto out_unlock;
}
} else if (disable & (1 << ssid)) {
if (!(cgrp->child_subsys_mask & (1 << ssid))) {
disable &= ~(1 << ssid);
@ -2673,12 +2673,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
goto out_unlock;
}
/*
* Create csses for enables and update child_subsys_mask. This
* changes cgroup_e_css() results which in turn makes the
* subsequent cgroup_update_dfl_csses() associate all tasks in the
* subtree to the updated csses.
*/
cgrp->child_subsys_mask |= enable;
cgrp->child_subsys_mask &= ~disable;
/* create new csses */
for_each_subsys(ss, ssid) {
if (!(enable & (1 << ssid)))
continue;
@ -2690,9 +2688,11 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
}
}
cgrp->child_subsys_mask |= enable;
cgrp->child_subsys_mask &= ~disable;
/*
* At this point, cgroup_e_css() results reflect the new csses
* making the following cgroup_update_dfl_csses() properly update
* css associations of all tasks in the subtree.
*/
ret = cgroup_update_dfl_csses(cgrp);
if (ret)
goto err_undo_css;