mptcp: implement mptcp_pm_remove_subflow

This patch implemented the local subflow removing function,
mptcp_pm_remove_subflow, it simply called mptcp_pm_nl_rm_subflow_received
under the PM spin lock.

We use mptcp_pm_remove_subflow to remove a local subflow, so change it's
argument from remote_id to local_id.

We check subflow->local_id in mptcp_pm_nl_rm_subflow_received to remove
a subflow.
Suggested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Suggested-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/pm.c

@@ -33,9 +33,14 @@ int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
 	return 0;
 }
 
-int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id)
+int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 local_id)
 {
-	return -ENOTSUPP;
+	pr_debug("msk=%p, local_id=%d", msk, local_id);
+
+	spin_lock_bh(&msk->pm.lock);
+	mptcp_pm_nl_rm_subflow_received(msk, local_id);
+	spin_unlock_bh(&msk->pm.lock);
+	return 0;
 }
 
 /* path manager event handlers */

net/mptcp/pm_netlink.c

@@ -350,6 +350,39 @@ void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
 	}
 }
 
+void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk, u8 rm_id)
+{
+	struct mptcp_subflow_context *subflow, *tmp;
+	struct sock *sk = (struct sock *)msk;
+
+	pr_debug("subflow rm_id %d", rm_id);
+
+	if (!rm_id)
+		return;
+
+	if (list_empty(&msk->conn_list))
+		return;
+
+	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		int how = RCV_SHUTDOWN | SEND_SHUTDOWN;
+		long timeout = 0;
+
+		if (rm_id != subflow->local_id)
+			continue;
+
+		spin_unlock_bh(&msk->pm.lock);
+		mptcp_subflow_shutdown(sk, ssk, how);
+		__mptcp_close_ssk(sk, ssk, subflow, timeout);
+		spin_lock_bh(&msk->pm.lock);
+
+		msk->pm.local_addr_used--;
+		msk->pm.subflows--;
+
+		break;
+	}
+}
+
 static bool address_use_port(struct mptcp_pm_addr_entry *entry)
 {
 	return (entry->addr.flags &

net/mptcp/protocol.h

@@ -448,7 +448,7 @@ int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   const struct mptcp_addr_info *addr,
 			   bool echo);
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id);
-int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id);
+int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 local_id);
 
 static inline bool mptcp_pm_should_add_signal(struct mptcp_sock *msk)
 {
@@ -479,6 +479,7 @@ void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
 void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
 void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk);
 void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk);
+void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk, u8 rm_id);
 int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
 
 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)