Commit ddfcadab authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: update init_css() into init_and_link_css() 



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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent a2bed820

kernel/cgroup.c

+10 −8
Original line number Diff line number Diff line
@@ -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

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