[PATCH net-next v4 5/6] mptcp: support rstreason for passive reset

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

It relys on what reset options in the skb are as rfc8684 says. Reusing
this logic can save us much energy. This patch replaces most of the prior
NOT_SPECIFIED reasons.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/mptcp/subflow.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index ba0a252c113f..25eaad94cb79 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -308,8 +308,12 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 		return dst;
 
 	dst_release(dst);
-	if (!req->syncookie)
-		tcp_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	if (!req->syncookie) {
+		struct mptcp_ext *mpext = mptcp_get_ext(skb);
+		enum sk_rst_reason reason = convert_mptcp_reason(mpext->reset_reason);
+
+		tcp_request_sock_ops.send_reset(sk, skb, reason);
+	}
 	return NULL;
 }
 
@@ -375,8 +379,12 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 		return dst;
 
 	dst_release(dst);
-	if (!req->syncookie)
-		tcp6_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	if (!req->syncookie) {
+		struct mptcp_ext *mpext = mptcp_get_ext(skb);
+		enum sk_rst_reason reason = convert_mptcp_reason(mpext->reset_reason);
+
+		tcp6_request_sock_ops.send_reset(sk, skb, reason);
+	}
 	return NULL;
 }
 #endif
@@ -783,6 +791,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	bool fallback, fallback_is_fatal;
 	struct mptcp_sock *owner;
 	struct sock *child;
+	enum sk_rst_reason reason;
 
 	pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
 
@@ -911,7 +920,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	tcp_rsk(req)->drop_req = true;
 	inet_csk_prepare_for_destroy_sock(child);
 	tcp_done(child);
-	req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	reason = convert_mptcp_reason(mptcp_get_ext(skb)->reset_reason);
+	req->rsk_ops->send_reset(sk, skb, reason);
 
 	/* The last child reference will be released by the caller */
 	return child;
-- 
2.37.3