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authorTejun Heo <tj@kernel.org>2016-03-03 09:57:59 -0500
committerTejun Heo <tj@kernel.org>2016-03-03 09:57:59 -0500
commitbdb53bd797dcef46d1a252b9529f8fd511bf714c (patch)
tree28d344a6ebeecc252596933257412a92f3ab1626 /kernel/cgroup.c
parent12b3bb6af862477f96e1adac51b201a143a8f3c4 (diff)
downloadlinux-sh-bdb53bd797dcef46d1a252b9529f8fd511bf714c.tar.gz
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: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c77
1 files changed, 47 insertions, 30 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 97cb1315bcac..1193038d0729 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3013,6 +3013,49 @@ static bool cgroup_drain_offline(struct cgroup *cgrp)
}
/**
+ * 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);
- if (ret)
- goto err_undo_css;
- }
- }
- } while_each_subsys_mask();
+ /* prepare csses */
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ goto err_undo_css;
/*
* At this point, cgroup_e_css() results reflect the new csses