tcp_metrics: use dst_dev_net_rcu()

Replace three dst_dev() with a lockdep enabled helper.

Fixes: 4a6ce2b ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: David Ahern <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: edumazet

net/ipv4/tcp_metrics.c

@@ -170,7 +170,7 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 	struct net *net;
 
 	spin_lock_bh(&tcp_metrics_lock);
-	net = dev_net_rcu(dst_dev(dst));
+	net = dst_dev_net_rcu(dst);
 
 	/* While waiting for the spin-lock the cache might have been populated
 	 * with this entry and so we have to check again.
@@ -273,7 +273,7 @@ static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 		return NULL;
 	}
 
-	net = dev_net_rcu(dst_dev(dst));
+	net = dst_dev_net_rcu(dst);
 	hash ^= net_hash_mix(net);
 	hash = hash_32(hash, tcp_metrics_hash_log);
 
@@ -318,7 +318,7 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 	else
 		return NULL;
 
-	net = dev_net_rcu(dst_dev(dst));
+	net = dst_dev_net_rcu(dst);
 	hash ^= net_hash_mix(net);
 	hash = hash_32(hash, tcp_metrics_hash_log);