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Commit cd497885 authored by Sridhar Samudrala's avatar Sridhar Samudrala Committed by David S. Miller
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[SCTP]: Include sk_buff overhead while updating the peer's receive window. 



Currently if the sender is sending small messages, it can cause a receiver
to run out of receive buffer space even when the advertised receive window
is still open and results in packet drops and retransmissions. Including
a overhead while updating the sender's view of peer receive window will
reduce the chances of receive buffer space overshooting the receive window.

Signed-off-by: default avatarSridhar Samudrala <sri@us.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 208edef6

net/sctp/output.c

+8 −2
Original line number Diff line number Diff line
@@ -633,7 +633,7 @@ static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, 
		 * data will fit or delay in hopes of bundling a full

		 * sized packet.

		 */

		if (len < asoc->pathmtu - packet->overhead) {

		if (len < asoc->frag_point) {

			retval = SCTP_XMIT_NAGLE_DELAY;

			goto finish;

		}
@@ -645,7 +645,13 @@ static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, 
	/* Keep track of how many bytes are in flight to the receiver. */

	asoc->outqueue.outstanding_bytes += datasize;



	/* Update our view of the receiver's rwnd. */

	/* Update our view of the receiver's rwnd. Include sk_buff overhead

	 * while updating peer.rwnd so that it reduces the chances of a

	 * receiver running out of receive buffer space even when receive

	 * window is still open. This can happen when a sender is sending

	 * sending small messages.

	 */

	datasize += sizeof(struct sk_buff);

	if (datasize < rwnd)

		rwnd -= datasize;

	else

net/sctp/outqueue.c

+2 −1
Original line number Diff line number Diff line
@@ -416,7 +416,8 @@ void sctp_retransmit_mark(struct sctp_outq *q, 
			 * (Section 7.2.4)), add the data size of those

			 * chunks to the rwnd.

			 */

			q->asoc->peer.rwnd += sctp_data_size(chunk);

			q->asoc->peer.rwnd += (sctp_data_size(chunk) +

						sizeof(struct sk_buff));

			q->outstanding_bytes -= sctp_data_size(chunk);

			transport->flight_size -= sctp_data_size(chunk);