mptcp: add the outgoing MP_PRIO support

This patch added the outgoing MP_PRIO logic:

In mptcp_pm_nl_mp_prio_send_ack, find the related subflow and subsocket
according to the input parameter addr. Save the input priority value to
suflow's backup, then set subflow's send_mp_prio flag to true, and save
the input priority value to suflow's request_bkup. Finally, send out a
pure ACK on the related subsocket.

In mptcp_established_options_mp_prio, check whether the subflow's
send_mp_prio is set. If it is, this is the packet for sending MP_PRIO.
So save subflow->request_bkup value to mptcp_out_options's backup, and
change the option type to OPTION_MPTCP_PRIO.

In mptcp_write_options, clear the send_mp_prio flag and send out the
MP_PRIO suboption with mptcp_out_options's backup value.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 7fe7be4eef7e..bf0d13c85a68 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -442,6 +442,39 @@ void mptcp_pm_nl_add_addr_send_ack(struct mptcp_sock *msk)
 	}
 }
 
+int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
+				 struct mptcp_addr_info *addr,
+				 u8 bkup)
+{
+	struct mptcp_subflow_context *subflow;
+
+	pr_debug("bkup=%d", bkup);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		struct mptcp_addr_info local;
+
+		local_address((struct sock_common *)ssk, &local);
+		if (!addresses_equal(&local, addr, addr->port))
+			continue;
+
+		subflow->backup = bkup;
+		subflow->send_mp_prio = 1;
+		subflow->request_bkup = bkup;
+
+		spin_unlock_bh(&msk->pm.lock);
+		pr_debug("send ack for mp_prio");
+		lock_sock(ssk);
+		tcp_send_ack(ssk);
+		release_sock(ssk);
+		spin_lock_bh(&msk->pm.lock);
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow, *tmp;