mptcp: rename fourth ack field

The name is misleading, it actually tracks the 'fully established'
status.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/options.c

@@ -259,11 +259,11 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 	struct mptcp_ext *mpext;
 	unsigned int data_len;
 
-	pr_debug("subflow=%p fourth_ack=%d seq=%x:%x remaining=%d", subflow,
-		 subflow->fourth_ack, subflow->snd_isn,
+	pr_debug("subflow=%p fully established=%d seq=%x:%x remaining=%d",
+		 subflow, subflow->fully_established, subflow->snd_isn,
 		 skb ? TCP_SKB_CB(skb)->seq : 0, remaining);
 
-	if (subflow->mp_capable && !subflow->fourth_ack && skb &&
+	if (subflow->mp_capable && !subflow->fully_established && skb &&
 	    subflow->snd_isn == TCP_SKB_CB(skb)->seq) {
 		/* When skb is not available, we better over-estimate the
 		 * emitted options len. A full DSS option is longer than
@@ -429,19 +429,19 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 	return false;
 }
 
-static bool check_fourth_ack(struct mptcp_subflow_context *subflow,
-			     struct sk_buff *skb,
-			     struct mptcp_options_received *mp_opt)
+static bool check_fully_established(struct mptcp_subflow_context *subflow,
+				    struct sk_buff *skb,
+				    struct mptcp_options_received *mp_opt)
 {
 	/* here we can process OoO, in-window pkts, only in-sequence 4th ack
 	 * are relevant
 	 */
-	if (likely(subflow->fourth_ack ||
+	if (likely(subflow->fully_established ||
 		   TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1))
 		return true;
 
 	if (mp_opt->use_ack)
-		subflow->fourth_ack = 1;
+		subflow->fully_established = 1;
 
 	if (subflow->can_ack)
 		return true;
@@ -467,7 +467,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 	struct mptcp_ext *mpext;
 
 	mp_opt = &opt_rx->mptcp;
-	if (!check_fourth_ack(subflow, skb, mp_opt))
+	if (!check_fully_established(subflow, skb, mp_opt))
 		return;
 
 	if (!mp_opt->dss)

net/mptcp/protocol.h

@@ -119,7 +119,7 @@ struct mptcp_subflow_context {
 	u32	map_data_len;
 	u32	request_mptcp : 1,  /* send MP_CAPABLE */
 		mp_capable : 1,	    /* remote is MPTCP capable */
-		fourth_ack : 1,	    /* send initial DSS */
+		fully_established : 1,	    /* path validated */
 		conn_finished : 1,
 		map_valid : 1,
 		mpc_map : 1,

net/mptcp/subflow.c

@@ -802,7 +802,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
 	new_ctx->tcp_sock = newsk;
 
 	new_ctx->mp_capable = 1;
-	new_ctx->fourth_ack = subflow_req->remote_key_valid;
+	new_ctx->fully_established = subflow_req->remote_key_valid;
 	new_ctx->can_ack = subflow_req->remote_key_valid;
 	new_ctx->remote_key = subflow_req->remote_key;
 	new_ctx->local_key = subflow_req->local_key;