[PATCH mptcp] net: mptcp: add statistics for mptcp socket in use

[menglong8.dong@gmail.com]

From: Menglong Dong <imagedong@tencent.com>

Do the statistics of mptcp socket in use with sock_prot_inuse_add().
Therefore, we can get the count of used mptcp socket from
/proc/net/protocols:

& cat /proc/net/protocols
protocol  size sockets  memory press maxhdr  slab module     cl co di ac io in de sh ss gs se re sp bi br ha uh gp em
MPTCPv6   2048      0       0   no       0   yes  kernel      y  n  y  y  y  y  y  y  y  y  y  y  n  n  n  y  y  y  n
MPTCP     1896      1       0   no       0   yes  kernel      y  n  y  y  y  y  y  y  y  y  y  y  n  n  n  y  y  y  n

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 net/mptcp/protocol.c | 19 +++++++++++++------
 net/mptcp/subflow.c  |  3 +++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 45ed50e9aec9..4da77aa8b070 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2311,6 +2311,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 			tcp_set_state(ssk, TCP_CLOSE);
 			mptcp_subflow_queue_clean(ssk);
 			inet_csk_listen_stop(ssk);
+			sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 		}
 		__tcp_close(ssk, 0);
 
@@ -3067,6 +3068,9 @@ void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
 	skb_rbtree_purge(&msk->out_of_order_queue);
 	mptcp_data_unlock(sk);
 
+	if (!sk_unhashed(sk) || __mptcp_check_fallback(msk))
+		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+
 	/* move all the rx fwd alloc into the sk_mem_reclaim_final in
 	 * inet_sock_destruct() will dispose it
 	 */
@@ -3513,6 +3517,7 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	mptcp_token_destroy(msk);
 	inet_sk_state_store(sock->sk, TCP_SYN_SENT);
 	subflow = mptcp_subflow_ctx(ssock->sk);
+	sock_prot_inuse_add(sock_net(sock->sk), sock->sk->sk_prot, 1);
 #ifdef CONFIG_TCP_MD5SIG
 	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 	 * TCP option space.
@@ -3547,12 +3552,13 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 static int mptcp_listen(struct socket *sock, int backlog)
 {
 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
+	struct sock *sk = sock->sk;
 	struct socket *ssock;
 	int err;
 
 	pr_debug("msk=%p", msk);
 
-	lock_sock(sock->sk);
+	lock_sock(sk);
 	ssock = __mptcp_nmpc_socket(msk);
 	if (!ssock) {
 		err = -EINVAL;
@@ -3560,16 +3566,17 @@ static int mptcp_listen(struct socket *sock, int backlog)
 	}
 
 	mptcp_token_destroy(msk);
-	inet_sk_state_store(sock->sk, TCP_LISTEN);
-	sock_set_flag(sock->sk, SOCK_RCU_FREE);
+	inet_sk_state_store(sk, TCP_LISTEN);
+	sock_set_flag(sk, SOCK_RCU_FREE);
+	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 
 	err = ssock->ops->listen(ssock, backlog);
-	inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
+	inet_sk_state_store(sk, inet_sk_state_load(ssock->sk));
 	if (!err)
-		mptcp_copy_inaddrs(sock->sk, ssock->sk);
+		mptcp_copy_inaddrs(sk, ssock->sk);
 
 unlock:
-	release_sock(sock->sk);
+	release_sock(sk);
 	return err;
 }
 
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 07dd23d0fe04..da6cfa73a3bd 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -747,6 +747,9 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 			mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
 			mptcp_pm_new_connection(mptcp_sk(new_msk), child, 1);
 			mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
+			sock_prot_inuse_add(sock_net(new_msk),
+					    new_msk->sk_prot,
+					    1);
 			ctx->conn = new_msk;
 			new_msk = NULL;
 
-- 
2.37.2