Commit bdb53bd7 authored by Tejun Heo's avatar Tejun Heo

cgroup: factor out cgroup_apply_control_enable() from cgroup_subtree_control_write()

Factor out css enabling and showing into cgroup_apply_control_enable().

* Nest subsystem walk inside child walk.  The child walk will later be
  converted to subtree walk which is a bit more expensive.

* Instead of operating on the differential masks @css_enable, simply
  enable or show csses according to the current cgroup_control() and
  cgroup_ss_mask().  This leads to the same result and is simpler and
  more robust.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent 12b3bb6a
......@@ -3012,6 +3012,49 @@ static bool cgroup_drain_offline(struct cgroup *cgrp)
return false;
}
/**
* cgroup_apply_control_enable - enable or show csses according to control
* @cgrp: parent of the target cgroups
*
* Walk @cgrp's children and create new csses or make the existing ones
* visible. A css is created invisible if it's being implicitly enabled
* through dependency. An invisible css is made visible when the userland
* explicitly enables it.
*
* Returns 0 on success, -errno on failure. On failure, csses which have
* been processed already aren't cleaned up. The caller is responsible for
* cleaning up with cgroup_apply_control_disble().
*/
static int cgroup_apply_control_enable(struct cgroup *cgrp)
{
struct cgroup *dsct;
struct cgroup_subsys *ss;
int ssid, ret;
cgroup_for_each_live_child(dsct, cgrp) {
for_each_subsys(ss, ssid) {
struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
continue;
if (!css) {
css = css_create(dsct, ss);
if (IS_ERR(css))
return PTR_ERR(css);
}
if (cgroup_control(dsct) & (1 << ss->id)) {
ret = css_populate_dir(css, NULL);
if (ret)
return ret;
}
}
}
return 0;
}
/**
* cgroup_apply_control_disable - kill or hide csses according to control
* @cgrp: parent of the target cgroups
......@@ -3157,36 +3200,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
cgrp->subtree_control = new_sc;
cgrp->subtree_ss_mask = new_ss;
/*
* Create new csses or make the existing ones visible. A css is
* created invisible if it's being implicitly enabled through
* dependency. An invisible css is made visible when the userland
* explicitly enables it.
*/
do_each_subsys_mask(ss, ssid, enable) {
cgroup_for_each_live_child(child, cgrp) {
if (css_enable & (1 << ssid)) {
struct cgroup_subsys_state *css;
css = css_create(child, ss);
if (IS_ERR(css)) {
ret = PTR_ERR(css);
goto err_undo_css;
}
if (cgrp->subtree_control & (1 << ssid)) {
ret = css_populate_dir(css, NULL);
if (ret)
goto err_undo_css;
}
} else {
ret = css_populate_dir(cgroup_css(child, ss),
NULL);
/* prepare csses */
ret = cgroup_apply_control_enable(cgrp);
if (ret)
goto err_undo_css;
}
}
} while_each_subsys_mask();
/*
* At this point, cgroup_e_css() results reflect the new csses
......
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