init_css() takes the cgroup the new css belongs to as an argument and
initializes the new css's ->cgroup and ->parent pointers but doesn't
acquire the matching reference counts. After the previous patch,
create_css() puts init_css() and reference acquisition right next to
each other. Let's move reference acquistion into init_css() and
rename the function to init_and_link_css(). This makes sense and is
easier to follow. This makes the root csses to hold a reference on
cgrp_dfl_root.cgrp, which is harmless.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
kernel/cgroup.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0e2c401..f1c98c5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4109,17 +4109,21 @@ static void css_release(struct percpu_ref *ref)
call_rcu(&css->rcu_head, css_free_rcu_fn);
}
-static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,
- struct cgroup *cgrp)
+static void init_and_link_css(struct cgroup_subsys_state *css,
+ struct cgroup_subsys *ss, struct cgroup *cgrp)
{
+ cgroup_get(cgrp);
+
css->cgroup = cgrp;
css->ss = ss;
css->flags = 0;
- if (cgrp->parent)
+ if (cgrp->parent) {
css->parent = cgroup_css(cgrp->parent, ss);
- else
+ css_get(css->parent);
+ } else {
css->flags |= CSS_ROOT;
+ }
BUG_ON(cgroup_css(cgrp, ss));
}
@@ -4185,9 +4189,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
if (IS_ERR(css))
return PTR_ERR(css);
- init_css(css, ss, cgrp);
- cgroup_get(cgrp);
- css_get(css->parent);
+ init_and_link_css(css, ss, cgrp);
err = percpu_ref_init(&css->refcnt, css_release);
if (err)
@@ -4656,7 +4658,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
- init_css(css, ss, &cgrp_dfl_root.cgrp);
+ init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
/* Update the init_css_set to contain a subsys
* pointer to this state - since the subsystem is
--
1.9.0
--
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