[PATCH net-next v7 02/11] net: tunnel: convert iptunnel_xmit to noref

[Marek Mietus <mmietus97@yahoo.com>]

iptunnel_xmit assumes that a reference was taken on the dst passed to it,
and uses that reference.

This forces callers to reference the dst, preventing noref optimizations.

Convert iptunnel_xmit to be noref and drop the requirement that a ref be
taken on the dst.

Signed-off-by: Marek Mietus <mmietus97@yahoo.com>
---
 net/ipv4/ip_tunnel.c       | 2 ++
 net/ipv4/ip_tunnel_core.c  | 2 +-
 net/ipv4/udp_tunnel_core.c | 3 +++
 net/ipv6/sit.c             | 1 +
 4 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 50d0f5fe4e4c..2136a46bcdc5 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -655,6 +655,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, proto, tos, ttl,
 		      df, !net_eq(tunnel->net, dev_net(dev)), 0);
+	ip_rt_put(rt);
 	return;
 tx_error:
 	DEV_STATS_INC(dev, tx_errors);
@@ -844,6 +845,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
 		      df, !net_eq(tunnel->net, dev_net(dev)), 0);
+	ip_rt_put(rt);
 	return;
 
 #if IS_ENABLED(CONFIG_IPV6)
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 2e61ac137128..70f0f123b0ba 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -61,7 +61,7 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 	skb_scrub_packet(skb, xnet);
 
 	skb_clear_hash_if_not_l4(skb);
-	skb_dst_set(skb, &rt->dst);
+	skb_dst_set_noref(skb, &rt->dst);
 	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 	IPCB(skb)->flags = ipcb_flags;
 
diff --git a/net/ipv4/udp_tunnel_core.c b/net/ipv4/udp_tunnel_core.c
index b1f667c52cb2..8a91f36cc052 100644
--- a/net/ipv4/udp_tunnel_core.c
+++ b/net/ipv4/udp_tunnel_core.c
@@ -190,8 +190,11 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
 
 	udp_set_csum(nocheck, skb, src, dst, skb->len);
 
+	rcu_read_lock();
 	iptunnel_xmit(sk, rt, skb, src, dst, IPPROTO_UDP, tos, ttl, df, xnet,
 		      ipcb_flags);
+	rcu_read_unlock();
+	ip_rt_put(rt);
 }
 EXPORT_SYMBOL_GPL(udp_tunnel_xmit_skb);
 
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index cf37ad9686e6..a0d699082747 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1028,6 +1028,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 
 	iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
 		      df, !net_eq(tunnel->net, dev_net(dev)), 0);
+	ip_rt_put(rt);
 	return NETDEV_TX_OK;
 
 tx_error_icmp:
-- 
2.51.0