Commit 723189fa authored by David Laight's avatar David Laight Committed by David S. Miller
Browse files

net: sctp: Open out the check for Nagle 



The check for Nagle contains 6 separate checks all of which must be true
before a data packet is delayed.
Separate out each into its own 'if (test) return SCTP_XMIT_OK' so that
the reasons can be individually described.

Also return directly with SCTP_XMIT_RWND_FULL.
Delete the now-unused 'retval' variable and 'finish' label from
sctp_packet_can_append_data().

Signed-off-by: default avatarDavid Laight <david.laight@aculab.com>
Acked-by: default avatarVlad Yasevich <vyasevich@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8fd90bb8

net/sctp/output.c

+36 −33
Original line number Diff line number Diff line
@@ -633,7 +633,6 @@ nomem: 
static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet,

					   struct sctp_chunk *chunk)

{

	sctp_xmit_t retval = SCTP_XMIT_OK;

	size_t datasize, rwnd, inflight, flight_size;

	struct sctp_transport *transport = packet->transport;

	struct sctp_association *asoc = transport->asoc;
@@ -658,15 +657,11 @@ static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 


	datasize = sctp_data_size(chunk);



	if (datasize > rwnd) {

		if (inflight > 0) {

	if (datasize > rwnd && inflight > 0)

		/* We have (at least) one data chunk in flight,

		 * so we can't fall back to rule 6.1 B).

		 */

			retval = SCTP_XMIT_RWND_FULL;

			goto finish;

		}

	}

		return SCTP_XMIT_RWND_FULL;



	/* RFC 2960 6.1  Transmission of DATA Chunks

	 *
@@ -680,36 +675,44 @@ static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, 
	 *    When a Fast Retransmit is being performed the sender SHOULD

	 *    ignore the value of cwnd and SHOULD NOT delay retransmission.

	 */

	if (chunk->fast_retransmit != SCTP_NEED_FRTX)

		if (flight_size >= transport->cwnd) {

			retval = SCTP_XMIT_RWND_FULL;

			goto finish;

		}

	if (chunk->fast_retransmit != SCTP_NEED_FRTX &&

	    flight_size >= transport->cwnd)

		return SCTP_XMIT_RWND_FULL;



	/* Nagle's algorithm to solve small-packet problem:

	 * Inhibit the sending of new chunks when new outgoing data arrives

	 * if any previously transmitted data on the connection remains

	 * unacknowledged.

	 */

	if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) &&

	    inflight && sctp_state(asoc, ESTABLISHED)) {

		unsigned int max = transport->pathmtu - packet->overhead;

		unsigned int len = chunk->skb->len + q->out_qlen;



		/* Check whether this chunk and all the rest of pending

		 * data will fit or delay in hopes of bundling a full

		 * sized packet.

		 * Don't delay large message writes that may have been

		 * fragmeneted into small peices.

	if (sctp_sk(asoc->base.sk)->nodelay)

		/* Nagle disabled */

		return SCTP_XMIT_OK;



	if (!sctp_packet_empty(packet))

		/* Append to packet */

		return SCTP_XMIT_OK;



	if (inflight == 0)

		/* Nothing unacked */

		return SCTP_XMIT_OK;



	if (!sctp_state(asoc, ESTABLISHED))

		return SCTP_XMIT_OK;



	/* Check whether this chunk and all the rest of pending data will fit

	 * or delay in hopes of bundling a full sized packet.

	 */

		if ((len < max) && chunk->msg->can_delay) {

			retval = SCTP_XMIT_NAGLE_DELAY;

			goto finish;

		}

	}

	if (chunk->skb->len + q->out_qlen >= transport->pathmtu - packet->overhead)

		/* Enough data queued to fill a packet */

		return SCTP_XMIT_OK;



finish:

	return retval;

	/* Don't delay large message writes that may have been fragmented */

	if (!chunk->msg->can_delay)

		return SCTP_XMIT_OK;



	/* Defer until all data acked or packet full */

	return SCTP_XMIT_NAGLE_DELAY;

}



/* This private function does management things when adding DATA chunk */

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