netdev - [PATCH] net: sched: cls_cgroup tear down exts and ematch from rcu callback

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Message-ID: <20141003163333.20118.59609.stgit@nitbit.x32>
Date:	Fri, 03 Oct 2014 09:33:35 -0700
From:	John Fastabend <john.fastabend@...il.com>
To:	xiyou.wangcong@...il.com, davem@...emloft.net
Cc:	netdev@...r.kernel.org, jhs@...atatu.com, eric.dumazet@...il.com
Subject: [PATCH] net: sched: cls_cgroup tear down exts and ematch from rcu
 callback

It is not RCU safe to destroy the action chain while there
is a possibility of readers accessing it. Move this code
into the rcu callback using the same rcu callback used in the
code patch to make a change to head.

Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
---
 net/sched/cls_cgroup.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index d4fef3a..dead710 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -156,10 +156,8 @@ static void cls_cgroup_destroy(struct tcf_proto *tp)
 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 
 	if (head) {
-		tcf_exts_destroy(&head->exts);
-		tcf_em_tree_destroy(head->net, &head->ematches);
 		RCU_INIT_POINTER(tp->root, NULL);
-		kfree_rcu(head, rcu);
+		call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
 	}
 }
 

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