[PATCH net-next v3 6/7] mptcp: avoid code duplication in __mptcp_move_skb()

[Matthieu Baerts (NGI0)]

From: Paolo Abeni <pabeni@xxxxxxxxxx>

Alike TCP, MPTCP handles in-sequence packets and partially overlapping
ones in a very similar way: we can use the same path to handle both,
avoiding some code duplication.

This will also make the next patch simpler.

Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
---
v3: new
---
 net/mptcp/protocol.c | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d96fbdc34dbb..63f2c18bc01f 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -399,6 +399,7 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
 
 	if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) {
 		/* in sequence */
+insert:
 		msk->bytes_received += copy_len;
 		WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
 		tail = skb_peek_tail(&sk->sk_receive_queue);
@@ -413,26 +414,20 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
 		return false;
 	}
 
-	/* Completely old data? */
-	if (!after64(MPTCP_SKB_CB(skb)->end_seq, msk->ack_seq)) {
-		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
-		mptcp_drop(sk, skb);
-		return false;
+	/* Partial packet */
+	if (after64(MPTCP_SKB_CB(skb)->end_seq, msk->ack_seq)) {
+		copy_len = MPTCP_SKB_CB(skb)->end_seq - msk->ack_seq;
+		MPTCP_SKB_CB(skb)->offset += msk->ack_seq -
+					     MPTCP_SKB_CB(skb)->map_seq;
+		MPTCP_SKB_CB(skb)->map_seq += msk->ack_seq -
+					      MPTCP_SKB_CB(skb)->map_seq;
+		goto insert;
 	}
 
-	/* Partial packet: map_seq < ack_seq < end_seq.
-	 * Skip the already-acked bytes and enqueue the new data.
-	 */
-	copy_len = MPTCP_SKB_CB(skb)->end_seq - msk->ack_seq;
-	MPTCP_SKB_CB(skb)->offset += msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
-	MPTCP_SKB_CB(skb)->map_seq += msk->ack_seq -
-				      MPTCP_SKB_CB(skb)->map_seq;
-	msk->bytes_received += copy_len;
-	WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
-
-	skb_set_owner_r(skb, sk);
-	__skb_queue_tail(&sk->sk_receive_queue, skb);
-	return true;
+	/* Completely old data */
+	MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
+	mptcp_drop(sk, skb);
+	return false;
 }
 
 static void mptcp_stop_rtx_timer(struct sock *sk)

-- 
2.53.0