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 <t...@kernel.org>
---
kernel/cgroup.c | 77 +++++++++++++++++++++++++++++++++++----------------------
1 file changed, 47 insertions(+), 30 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index da178ed..5a5cb52 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3008,6 +3008,49 @@ 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
*
@@ -3155,36 +3198,10 @@ 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
--
2.5.0
