From: Jiri Pirko <jiri@mellanox.com>
Date: Sat, 20 May 2017 15:01:32 +0200
Subject: net/sched: fix filter flushing
Patch-mainline: v4.13-rc1
Git-commit: f93e1cdcf42c1218e2a73be477d8ac21135e7f56
References: bsc#1056787

When user instructs to remove all filters from chain, we cannot destroy
the chain as other actions may hold a reference. Also the put in errout
would try to destroy it again. So instead, just walk the chain and remove
all existing filters.

Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/cls_api.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -201,15 +201,22 @@ static struct tcf_chain *tcf_chain_creat
 	return chain;
 }
 
-static void tcf_chain_destroy(struct tcf_chain *chain)
+static void tcf_chain_flush(struct tcf_chain *chain)
 {
 	struct tcf_proto *tp;
 
-	list_del(&chain->list);
+	if (*chain->p_filter_chain)
+		RCU_INIT_POINTER(*chain->p_filter_chain, NULL);
 	while ((tp = rtnl_dereference(chain->filter_chain)) != NULL) {
 		RCU_INIT_POINTER(chain->filter_chain, tp->next);
 		tcf_proto_destroy(tp);
 	}
+}
+
+static void tcf_chain_destroy(struct tcf_chain *chain)
+{
+	list_del(&chain->list);
+	tcf_chain_flush(chain);
 	kfree(chain);
 }
 
@@ -510,7 +517,7 @@ replay:
 
 	if (n->nlmsg_type == RTM_DELTFILTER && prio == 0) {
 		tfilter_notify_chain(net, skb, n, chain, RTM_DELTFILTER);
-		tcf_chain_destroy(chain);
+		tcf_chain_flush(chain);
 		err = 0;
 		goto errout;
 	}