net: Fix netns for ip_tunnel_init_flow()

The device denoted by tunnel->parms.link resides in the underlay net
namespace. Therefore pass tunnel->net to ip_tunnel_init_flow().

Fixes: db53cd3 ("net: Handle l3mdev in ip_tunnel_init_flow")
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20241219130336.103839-1-shaw.leon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: leonshaw

drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c

@@ -423,8 +423,7 @@ mlxsw_sp_span_gretap4_route(const struct net_device *to_dev,
 
 	parms = mlxsw_sp_ipip_netdev_parms4(to_dev);
 	ip_tunnel_init_flow(&fl4, parms.iph.protocol, *daddrp, *saddrp,
-			    0, 0, dev_net(to_dev), parms.link, tun->fwmark, 0,
-			    0);
+			    0, 0, tun->net, parms.link, tun->fwmark, 0, 0);
 
 	rt = ip_route_output_key(tun->net, &fl4);
 	if (IS_ERR(rt))

net/ipv4/ip_tunnel.c

@@ -294,7 +294,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
 		ip_tunnel_init_flow(&fl4, iph->protocol, iph->daddr,
 				    iph->saddr, tunnel->parms.o_key,
-				    iph->tos & INET_DSCP_MASK, dev_net(dev),
+				    iph->tos & INET_DSCP_MASK, tunnel->net,
 				    tunnel->parms.link, tunnel->fwmark, 0, 0);
 		rt = ip_route_output_key(tunnel->net, &fl4);
 
@@ -611,7 +611,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 	}
 	ip_tunnel_init_flow(&fl4, proto, key->u.ipv4.dst, key->u.ipv4.src,
 			    tunnel_id_to_key32(key->tun_id),
-			    tos & INET_DSCP_MASK, dev_net(dev), 0, skb->mark,
+			    tos & INET_DSCP_MASK, tunnel->net, 0, skb->mark,
 			    skb_get_hash(skb), key->flow_flags);
 
 	if (!tunnel_hlen)
@@ -774,7 +774,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 
 	ip_tunnel_init_flow(&fl4, protocol, dst, tnl_params->saddr,
 			    tunnel->parms.o_key, tos & INET_DSCP_MASK,
-			    dev_net(dev), READ_ONCE(tunnel->parms.link),
+			    tunnel->net, READ_ONCE(tunnel->parms.link),
 			    tunnel->fwmark, skb_get_hash(skb), 0);
 
 	if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0)