[PATCH net-next 2/8] rxrpc: Send an immediate ACK if we fill in a hole

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH net-next 2/8] rxrpc: Send an immediate ACK if we fill in a hole
Date	2016-09-25 01:30 +0200
Message-ID	<sl4ym-7ou-23@gated-at.bofh.it> (permalink)
References	<sl4ym-7ou-7@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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Send an immediate ACK if we fill in a hole in the buffer left by an
out-of-sequence packet.  This may allow the congestion management in the peer
to avoid a retransmission if packets got reordered on the wire.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 net/rxrpc/input.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 349698d87ad1..757c16f033a0 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -331,8 +331,16 @@ next_subpacket:
 	call->rxtx_annotations[ix] = annotation;
 	smp_wmb();
 	call->rxtx_buffer[ix] = skb;
-	if (after(seq, call->rx_top))
+	if (after(seq, call->rx_top)) {
 		smp_store_release(&call->rx_top, seq);
+	} else if (before(seq, call->rx_top)) {
+		/* Send an immediate ACK if we fill in a hole */
+		if (!ack) {
+			ack = RXRPC_ACK_DELAY;
+			ack_serial = serial;
+		}
+		immediate_ack = true;
+	}
 	if (flags & RXRPC_LAST_PACKET) {
 		set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 		trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);

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[PATCH net-next 2/8] rxrpc: Send an immediate ACK if we fill in a  hole David Howells <dhowells@redhat.com> - 2016-09-25 01:30 +0200

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