Factor out css disabling and hiding into cgroup_apply_control_disable().
* 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 and
@css_disable, simply disable or hide csses according to the current
cgroup_control() and cgroup_ss_mask(). This leads to the same
result and is simpler and more robust.
* This allows error handling path to share the same code.
Signed-off-by: Tejun Heo <t...@kernel.org>
---
kernel/cgroup.c | 74 ++++++++++++++++++++++++++++++++-------------------------
1 file changed, 41 insertions(+), 33 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7966750..da178ed 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3007,6 +3007,43 @@ static bool cgroup_drain_offline(struct cgroup *cgrp)
return false;
}
+/**
+ * cgroup_apply_control_disable - kill or hide csses according to control
+ * @cgrp: parent of the target cgroups
+ *
+ * Walk @cgrp's children and kill and hide csses so that they match
+ * cgroup_ss_mask() and cgroup_visible_mask().
+ *
+ * A css is hidden when the userland requests it to be disabled while other
+ * subsystems are still depending on it. The css must not actively control
+ * resources and be in the vanilla state if it's made visible again later.
+ * Controllers which may be depended upon should provide ->css_reset() for
+ * this purpose.
+ */
+static void cgroup_apply_control_disable(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ cgroup_for_each_live_child(dsct, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+
+ if (!css)
+ continue;
+
+ if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) {
+ kill_css(css);
+ } else if (!(cgroup_control(dsct) & (1 << ss->id))) {
+ css_clear_dir(css, NULL);
+ if (ss->css_reset)
+ ss->css_reset(css);
+ }
+ }
+ }
+}
+
/* change the enabled child controllers for a cgroup in the default hierarchy
*/
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
@@ -3158,27 +3195,8 @@ static ssize_t cgroup_subtree_control_write(struct
kernfs_open_file *of,
if (ret)
goto err_undo_css;
- /*
- * All tasks are migrated out of disabled csses. Kill or hide
- * them. A css is hidden when the userland requests it to be
- * disabled while other subsystems are still depending on it. The
- * css must not actively control resources and be in the vanilla
- * state if it's made visible again later. Controllers which may
- * be depended upon should provide ->css_reset() for this purpose.
- */
- do_each_subsys_mask(ss, ssid, disable) {
- cgroup_for_each_live_child(child, cgrp) {
- struct cgroup_subsys_state *css = cgroup_css(child, ss);
-
- if (css_disable & (1 << ssid)) {
- kill_css(css);
- } else {
- css_clear_dir(css, NULL);
- if (ss->css_reset)
- ss->css_reset(css);
- }
- }
- } while_each_subsys_mask();
+ /* all tasks are migrated out of disabled csses, commit disable */
+ cgroup_apply_control_disable(cgrp);
kernfs_activate(cgrp->kn);
ret = 0;
@@ -3187,22 +3205,12 @@ static ssize_t cgroup_subtree_control_write(struct
kernfs_open_file *of,
return ret ?: nbytes;
err_undo_css:
+ /* restore masks and shoot down new csses */
cgrp->subtree_control = old_sc;
cgrp->subtree_ss_mask = old_ss;
- do_each_subsys_mask(ss, ssid, enable) {
- cgroup_for_each_live_child(child, cgrp) {
- struct cgroup_subsys_state *css = cgroup_css(child, ss);
-
- if (!css)
- continue;
+ cgroup_apply_control_disable(cgrp);
- if (css_enable & (1 << ssid))
- kill_css(css);
- else
- css_clear_dir(css, NULL);
- }
- } while_each_subsys_mask();
goto out_unlock;
}
--
2.5.0
