This is the mptcp counter-part of commit ea33537d8292 ("tcp: add receive
queue awareness in tcp_rcv_space_adjust()").

Prior to this commit:

ESTAB 33165568 0      192.168.255.2:5201 192.168.255.1:53380 \
	skmem:(r33076416,rb33554432,t0,tb91136,f448,w0,o0,bl0,d0)

After:
ESTAB 3279168 0      192.168.255.2:5201 192.168.255.1]:53042 \
	skmem:(r3190912,rb3719956,t0,tb91136,f1536,w0,o0,bl0,d0)
(same tput)

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 50 +++++++++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 4fc1519baab6..37a90d644e7b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2105,6 +2105,27 @@ static void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
 		msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
 }
 
+static unsigned int mptcp_inq_hint(const struct sock *sk)
+{
+	const struct mptcp_sock *msk = mptcp_sk(sk);
+	const struct sk_buff *skb;
+
+	skb = skb_peek(&sk->sk_receive_queue);
+	if (skb) {
+		u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
+
+		if (hint_val >= INT_MAX)
+			return INT_MAX;
+
+		return (unsigned int)hint_val;
+	}
+
+	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
+		return 1;
+
+	return 0;
+}
+
 /* receive buffer autotuning.  See tcp_rcv_space_adjust for more information.
  *
  * Only difference: Use highest rtt estimate of the subflows in use.
@@ -2133,10 +2154,12 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
 	if (rtt_us == U32_MAX || time < (rtt_us >> 3))
 		return;
 
-	if (msk->rcvq_space.copied <= msk->rcvq_space.space)
+	copied = msk->rcvq_space.copied;
+	copied -= mptcp_inq_hint(sk);
+	if (copied <= msk->rcvq_space.space)
 		goto new_measure;
 
-	if (mptcp_rcvbuf_grow(sk, msk->rcvq_space.copied)) {
+	if (mptcp_rcvbuf_grow(sk, copied)) {
 
 		/* Make subflows follow along.  If we do not do this, we
 		 * get drops at subflow level if skbs can't be moved to
@@ -2150,7 +2173,7 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
 			ssk = mptcp_subflow_tcp_sock(subflow);
 			slow = lock_sock_fast(ssk);
 			if (tcp_sk(ssk)->rcvq_space.space)
-				tcp_rcvbuf_grow(ssk, msk->rcvq_space.copied);
+				tcp_rcvbuf_grow(ssk, copied);
 			unlock_sock_fast(ssk, slow);
 		}
 	}
@@ -2233,27 +2256,6 @@ static bool mptcp_move_skbs(struct sock *sk)
 	return enqueued;
 }
 
-static unsigned int mptcp_inq_hint(const struct sock *sk)
-{
-	const struct mptcp_sock *msk = mptcp_sk(sk);
-	const struct sk_buff *skb;
-
-	skb = skb_peek(&sk->sk_receive_queue);
-	if (skb) {
-		u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
-
-		if (hint_val >= INT_MAX)
-			return INT_MAX;
-
-		return (unsigned int)hint_val;
-	}
-
-	if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
-		return 1;
-
-	return 0;
-}
-
 static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 			 int flags, int *addr_len)
 {
-- 
2.51.0