mptcp: split __mptcp_close_ssk helper

Prepare for subflow close events:

When mptcp connection is torn down its enough to send the mptcp socket
close notification rather than a subflow close event for all of the
subflows followed by the mptcp close event.

This splits the helper: mptcp_close_ssk() will emit the close
notification, __mptcp_close_ssk will not.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

net/mptcp/pm_netlink.c

@@ -594,7 +594,7 @@ static void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
 
 		spin_unlock_bh(&msk->pm.lock);
 		mptcp_subflow_shutdown(sk, ssk, how);
-		__mptcp_close_ssk(sk, ssk, subflow);
+		mptcp_close_ssk(sk, ssk, subflow);
 		spin_lock_bh(&msk->pm.lock);
 
 		msk->pm.add_addr_accepted--;
@@ -664,7 +664,7 @@ void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk, u8 rm_id)
 
 		spin_unlock_bh(&msk->pm.lock);
 		mptcp_subflow_shutdown(sk, ssk, how);
-		__mptcp_close_ssk(sk, ssk, subflow);
+		mptcp_close_ssk(sk, ssk, subflow);
 		spin_lock_bh(&msk->pm.lock);
 
 		msk->pm.local_addr_used--;

net/mptcp/protocol.c

@@ -2114,8 +2114,8 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
  * so we need to use tcp_close() after detaching them from the mptcp
  * parent socket.
  */
-void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
-		       struct mptcp_subflow_context *subflow)
+static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
+			      struct mptcp_subflow_context *subflow)
 {
 	list_del(&subflow->node);
 
@@ -2147,6 +2147,12 @@ void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	sock_put(ssk);
 }
 
+void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
+		     struct mptcp_subflow_context *subflow)
+{
+	__mptcp_close_ssk(sk, ssk, subflow);
+}
+
 static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
 {
 	return 0;
@@ -2164,7 +2170,7 @@ static void __mptcp_close_subflow(struct mptcp_sock *msk)
 		if (inet_sk_state_load(ssk) != TCP_CLOSE)
 			continue;
 
-		__mptcp_close_ssk((struct sock *)msk, ssk, subflow);
+		mptcp_close_ssk((struct sock *)msk, ssk, subflow);
 	}
 }
 

net/mptcp/protocol.h

@@ -539,8 +539,8 @@ void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 bool mptcp_subflow_data_available(struct sock *sk);
 void __init mptcp_subflow_init(void);
 void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how);
-void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
-		       struct mptcp_subflow_context *subflow);
+void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
+		     struct mptcp_subflow_context *subflow);
 void mptcp_subflow_reset(struct sock *ssk);
 void mptcp_sock_graft(struct sock *sk, struct socket *parent);
 struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);