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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
commit12b3bb6af862477f96e1adac51b201a143a8f3c4 (patch)
tree8be60418534f5acce21fdc203112879ff187624a /kernel/cgroup.c
parent1b9b96a12b5433ccc477265111122720ccb4965e (diff)
downloadlinux-sh-12b3bb6af862477f96e1adac51b201a143a8f3c4.tar.gz
cgroup: factor out cgroup_apply_control_disable() from cgroup_subtree_control_write()
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 <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c74
1 files changed, 41 insertions, 33 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d295e6a91cdc..97cb1315bcac 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3012,6 +3012,43 @@ 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,
@@ -3160,27 +3197,8 @@ 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;
@@ -3189,22 +3207,12 @@ out_unlock:
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;
}