From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Tue, 23 May 2017 09:42:37 -0700
Subject: net_sched: only create filter chains for new filters/actions
Patch-mainline: v4.13-rc1
Git-commit: 367a8ce896f14018cc2c6cf2681aa440fff274f4
References: bsc#1056787

tcf_chain_get() always creates a new filter chain if not found
in existing ones. This is totally unnecessary when we get or
delete filters, new chain should be only created for new filters
(or new actions).

Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/net/pkt_cls.h |    3 ++-
 net/sched/act_api.c   |    2 +-
 net/sched/cls_api.c   |   13 +++++++++----
 3 files changed, 12 insertions(+), 6 deletions(-)

--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -18,7 +18,8 @@ int register_tcf_proto_ops(struct tcf_pr
 int unregister_tcf_proto_ops(struct tcf_proto_ops *ops);
 
 #ifdef CONFIG_NET_CLS
-struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index);
+struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
+				bool create);
 void tcf_chain_put(struct tcf_chain *chain);
 int tcf_block_get(struct tcf_block **p_block,
 		  struct tcf_proto __rcu **p_filter_chain);
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -34,7 +34,7 @@ static int tcf_action_goto_chain_init(st
 
 	if (!tp)
 		return -EINVAL;
-	a->goto_chain = tcf_chain_get(tp->chain->block, chain_index);
+	a->goto_chain = tcf_chain_get(tp->chain->block, chain_index, true);
 	if (!a->goto_chain)
 		return -ENOMEM;
 	return 0;
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -220,7 +220,8 @@ static void tcf_chain_destroy(struct tcf
 	kfree(chain);
 }
 
-struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index)
+struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
+				bool create)
 {
 	struct tcf_chain *chain;
 
@@ -230,7 +231,10 @@ struct tcf_chain *tcf_chain_get(struct t
 			return chain;
 		}
 	}
-	return tcf_chain_create(block, chain_index);
+	if (create)
+		return tcf_chain_create(block, chain_index);
+	else
+		return NULL;
 }
 EXPORT_SYMBOL(tcf_chain_get);
 
@@ -511,9 +515,10 @@ replay:
 		err = -EINVAL;
 		goto errout;
 	}
-	chain = tcf_chain_get(block, chain_index);
+	chain = tcf_chain_get(block, chain_index,
+			      n->nlmsg_type == RTM_NEWTFILTER);
 	if (!chain) {
-		err = -ENOMEM;
+		err = n->nlmsg_type == RTM_NEWTFILTER ? -ENOMEM : -EINVAL;
 		goto errout;
 	}