[PATCH net 1/2] mptcp: factor out __mptcp_close() without socket lock

[Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>]

From: Menglong Dong <imagedong@xxxxxxxxxxx>

Factor out __mptcp_close() from mptcp_close(). The caller of
__mptcp_close() should hold the socket lock, and cancel mptcp work when
__mptcp_close() returns true.

This function will be used in the next commit.

Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests")
Fixes: 6aeed9045071 ("mptcp: fix race on unaccepted mptcp sockets")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Jiang Biao <benbjiang@xxxxxxxxxxx>
Reviewed-by: Mengen Sun <mengensun@xxxxxxxxxxx>
Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx>
Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
---
 net/mptcp/protocol.c | 14 ++++++++++++--
 net/mptcp/protocol.h |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 969b33a9dd64..f7690414320a 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2802,13 +2802,12 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sock_put(sk);
 }
 
-static void mptcp_close(struct sock *sk, long timeout)
+bool __mptcp_close(struct sock *sk, long timeout)
 {
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	bool do_cancel_work = false;
 
-	lock_sock(sk);
 	sk->sk_shutdown = SHUTDOWN_MASK;
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
@@ -2850,6 +2849,17 @@ static void mptcp_close(struct sock *sk, long timeout)
 	} else {
 		mptcp_reset_timeout(msk, 0);
 	}
+
+	return do_cancel_work;
+}
+
+static void mptcp_close(struct sock *sk, long timeout)
+{
+	bool do_cancel_work;
+
+	lock_sock(sk);
+
+	do_cancel_work = __mptcp_close(sk, timeout);
 	release_sock(sk);
 	if (do_cancel_work)
 		mptcp_cancel_work(sk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 132d50833df1..8f123d450c76 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -612,6 +612,7 @@ void mptcp_subflow_reset(struct sock *ssk);
 void mptcp_subflow_queue_clean(struct sock *ssk);
 void mptcp_sock_graft(struct sock *sk, struct socket *parent);
 struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);
+bool __mptcp_close(struct sock *sk, long timeout);
 
 bool mptcp_addresses_equal(const struct mptcp_addr_info *a,
 			   const struct mptcp_addr_info *b, bool use_port);
-- 
2.37.3