[MPTCP][PATCH v3 mptcp-next 7/8] mptcp: infinite mapping receiving

[Geliang Tang <geliangtang@gmail.com>]

This patch added the infinite mapping receiving logic.

Added a new struct member infinite_mapping_received in struct
mptcp_subflow_context, set it true when the infinite mapping is
received.

In subflow_check_data_avail, if this flag is set, fallback to a regular
TCP.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 net/mptcp/protocol.h | 1 +
 net/mptcp/subflow.c  | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index fff2f5021619..4ee97e9ceece 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -424,6 +424,7 @@ struct mptcp_subflow_context {
 		send_mp_prio : 1,
 		send_mp_fail : 1,
 		mp_fail_need_echo : 1,
+		infinite_mapping_received : 1,
 		rx_eof : 1,
 		can_ack : 1,        /* only after processing the remote a key */
 		disposable : 1;	    /* ctx can be free at ulp release time */
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index d46c171ef9b0..987fb6b55145 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -965,7 +965,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
 
 	data_len = mpext->data_len;
 	if (data_len == 0) {
+		pr_debug("infinite mapping received, data_seq=%llu", mpext->data_seq);
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
+		subflow->infinite_mapping_received = 1;
 		return MAPPING_INVALID;
 	}
 
@@ -1179,6 +1181,13 @@ static bool subflow_check_data_avail(struct sock *ssk)
 		}
 	}
 
+	if (subflow->infinite_mapping_received) {
+		pr_fallback(msk);
+		__mptcp_do_fallback(msk);
+		subflow->infinite_mapping_received = 0;
+		return true;
+	}
+
 	if (subflow->mp_join || subflow->fully_established) {
 		/* fatal protocol error, close the socket.
 		 * subflow_error_report() will introduce the appropriate barriers
-- 
2.31.1