mptcp: use fast lock for subflows when possible

There are a bunch of callsite where the ssk socket
lock is acquired using the full-blown version eligible for
the fast variant. Let's move to the latter.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mptcp/pm_netlink.c

@@ -540,6 +540,7 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
 	subflow = list_first_entry_or_null(&msk->conn_list, typeof(*subflow), node);
 	if (subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
 		spin_unlock_bh(&msk->pm.lock);
 		pr_debug("send ack for %s%s%s",
@@ -547,9 +548,9 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
 			 mptcp_pm_should_add_signal_ipv6(msk) ? " [ipv6]" : "",
 			 mptcp_pm_should_add_signal_port(msk) ? " [port]" : "");
 
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 		spin_lock_bh(&msk->pm.lock);
 	}
 }
@@ -566,6 +567,7 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 		struct sock *sk = (struct sock *)msk;
 		struct mptcp_addr_info local;
+		bool slow;
 
 		local_address((struct sock_common *)ssk, &local);
 		if (!addresses_equal(&local, addr, addr->port))
@@ -578,9 +580,9 @@ int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 
 		spin_unlock_bh(&msk->pm.lock);
 		pr_debug("send ack for mp_prio");
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 		spin_lock_bh(&msk->pm.lock);
 
 		return 0;

net/mptcp/protocol.c

@@ -433,23 +433,25 @@ static void mptcp_send_ack(struct mptcp_sock *msk)
 
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
-		lock_sock(ssk);
+		slow = lock_sock_fast(ssk);
 		if (tcp_can_send_ack(ssk))
 			tcp_send_ack(ssk);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slow);
 	}
 }
 
 static bool mptcp_subflow_cleanup_rbuf(struct sock *ssk)
 {
+	bool slow;
 	int ret;
 
-	lock_sock(ssk);
+	slow = lock_sock_fast(ssk);
 	ret = tcp_can_send_ack(ssk);
 	if (ret)
 		tcp_cleanup_rbuf(ssk, 1);
-	release_sock(ssk);
+	unlock_sock_fast(ssk, slow);
 	return ret;
 }
 
@@ -2252,13 +2254,14 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 
 	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
-		lock_sock(tcp_sk);
+		slow = lock_sock_fast(tcp_sk);
 		if (tcp_sk->sk_state != TCP_CLOSE) {
 			tcp_send_active_reset(tcp_sk, GFP_ATOMIC);
 			tcp_set_state(tcp_sk, TCP_CLOSE);
 		}
-		release_sock(tcp_sk);
+		unlock_sock_fast(tcp_sk, slow);
 	}
 
 	inet_sk_state_store(sk, TCP_CLOSE);