linux-kernel - [RFC PATCH] cgroup: remove redundant cleanup in css

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Date:	Fri, 13 May 2016 22:59:20 +0800
From:	Wenwei Tao <wwtao0320@....com>
To:	tj@...nel.org, lizefan@...wei.com, hannes@...xchg.org
Cc:	ww.tao0320@...il.com, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH] cgroup: remove redundant cleanup in css_create

From: Wenwei Tao <ww.tao0320@...il.com>

When create css failed, before call css_free_rcu_fn,
we remove the css id and exit the percpu_ref, but we
will do these again in css_free_work_fn, so they are redundant.
Especially the css id, that would cause problem if we
remove it twice, since it may be assigned to another
css after the first remove.

Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
---
 kernel/cgroup.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 909a7d3..9df3a29 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5088,7 +5088,7 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
 
 	err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
 	if (err < 0)
-		goto err_free_percpu_ref;
+		goto err_free_css;
 	css->id = err;
 
 	/* @css is ready to be brought online now, make it visible */
@@ -5112,9 +5112,6 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
 
 err_list_del:
 	list_del_rcu(&css->sibling);
-	cgroup_idr_remove(&ss->css_idr, css->id);
-err_free_percpu_ref:
-	percpu_ref_exit(&css->refcnt);
 err_free_css:
 	call_rcu(&css->rcu_head, css_free_rcu_fn);
 	return ERR_PTR(err);
-- 
1.8.3.1