[PATCH net-next v8 05/11] net: ovpn: convert ovpn_udp{4,6}_output to use a noref dst

[Marek Mietus <mmietus97@yahoo.com>]

ovpn_udp{4,6}_output unnecessarily reference the dst_entry from the
dst_cache when interacting with the cache.

Reduce this overhead by avoiding the redundant refcount increments.

These changes are safe as both ipv4 and ip6 support noref xmit under RCU
which is already the case for ovpn.

Signed-off-by: Marek Mietus <mmietus97@yahoo.com>
---
 drivers/net/ovpn/udp.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c
index 2e202bd2b73f..d2900a3e96ac 100644
--- a/drivers/net/ovpn/udp.c
+++ b/drivers/net/ovpn/udp.c
@@ -158,7 +158,7 @@ static int ovpn_udp4_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 	int ret;
 
 	local_bh_disable();
-	rt = dst_cache_get_ip4(cache, &fl.saddr);
+	rt = dst_cache_get_ip4_rcu(cache, &fl.saddr);
 	if (rt)
 		goto transmit;
 
@@ -194,13 +194,12 @@ static int ovpn_udp4_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 				    ret);
 		goto err;
 	}
-	dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
+	dst_cache_steal_ip4(cache, &rt->dst, fl.saddr);
 
 transmit:
 	udp_tunnel_xmit_skb(rt, sk, skb, fl.saddr, fl.daddr, 0,
 			    ip4_dst_hoplimit(&rt->dst), 0, fl.fl4_sport,
 			    fl.fl4_dport, false, sk->sk_no_check_tx, 0);
-	ip_rt_put(rt);
 	ret = 0;
 err:
 	local_bh_enable();
@@ -236,7 +235,7 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 	};
 
 	local_bh_disable();
-	dst = dst_cache_get_ip6(cache, &fl.saddr);
+	dst = dst_cache_get_ip6_rcu(cache, &fl.saddr);
 	if (dst)
 		goto transmit;
 
@@ -260,7 +259,7 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 				    &bind->remote.in6, ret);
 		goto err;
 	}
-	dst_cache_set_ip6(cache, dst, &fl.saddr);
+	dst_cache_steal_ip6(cache, dst, &fl.saddr);
 
 transmit:
 	/* user IPv6 packets may be larger than the transport interface
@@ -276,7 +275,6 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 	udp_tunnel6_xmit_skb(dst, sk, skb, skb->dev, &fl.saddr, &fl.daddr, 0,
 			     ip6_dst_hoplimit(dst), 0, fl.fl6_sport,
 			     fl.fl6_dport, udp_get_no_check6_tx(sk), 0);
-	dst_release(dst);
 	ret = 0;
 err:
 	local_bh_enable();
-- 
2.51.0