[PATCH 3.16 161/294] l2tp: remove useless duplicate session detection in l2tp_netlink

[Ben Hutchings]

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Guillaume Nault <g.nault@xxxxxxxxxxxx>

commit af87ae465abdc070de0dc35d6c6a9e7a8cd82987 upstream.

There's no point in checking for duplicate sessions at the beginning of
l2tp_nl_cmd_session_create(); the ->session_create() callbacks already
return -EEXIST when the session already exists.

Furthermore, even if l2tp_session_find() returns NULL, a new session
might be created right after the test. So relying on ->session_create()
to avoid duplicate session is the only sane behaviour.

Signed-off-by: Guillaume Nault <g.nault@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16: also delete the now-unused local variable]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -415,7 +415,6 @@ static int l2tp_nl_cmd_session_create(st
 	u32 peer_session_id;
 	int ret = 0;
 	struct l2tp_tunnel *tunnel;
-	struct l2tp_session *session;
 	struct l2tp_session_cfg cfg = { 0, };
 	struct net *net = genl_info_net(info);
 
@@ -435,11 +434,6 @@ static int l2tp_nl_cmd_session_create(st
 		goto out;
 	}
 	session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);
-	session = l2tp_session_find(net, tunnel, session_id);
-	if (session) {
-		ret = -EEXIST;
-		goto out;
-	}
 
 	if (!info->attrs[L2TP_ATTR_PEER_SESSION_ID]) {
 		ret = -EINVAL;