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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2006-11-27 12:26:57 -0200
committerDavid S. Miller <davem@sunset.davemloft.net>2006-12-02 21:30:39 -0800
commitda335baf9e788edfb00ee3b96f7b9526b6b2f8a9 (patch)
tree1eea49e2f94f359d9293025c64f381d43dd5922f
parent7da7f456d7bc0e52009f882e8af0ac910293e157 (diff)
[DCCP] ccid3: Avoid congestion control on zero-sized data packets
This resolves an `XXX' in ccid3_hc_tx_send_packet(). The function is only called on Data and DataAck packets and returns a negative result on zero-sized messages. This is a reasonable policy since CCID 3 is a congestion-control module and congestion control on zero-sized Data(Ack) packets is in a way pathological. The patch uses a more suitable error code for this case, it returns the Posix.1 code `EBADMSG' ("Not a data message") instead of `ENOTCONN'. As a result of ignoring zero-sized packets, a the condition for a warning "First packet is data" in ccid3_hc_tx_packet_sent is always satisfied; this message has been removed since it will always be printed. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
-rw-r--r--net/dccp/ccids/ccid3.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 2745d835f03..62c304200ed 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -264,13 +264,13 @@ static int ccid3_hc_tx_send_packet(struct sock *sk,
BUG_ON(hctx == NULL);
- /* Check if pure ACK or Terminating*/
/*
- * XXX: We only call this function for DATA and DATAACK, on, these
- * packets can have zero length, but why the comment about "pure ACK"?
+ * This function is called only for Data and DataAck packets. Sending
+ * zero-sized Data(Ack)s is theoretically possible, but for congestion
+ * control this case is pathological - ignore it.
*/
if (unlikely(len == 0))
- return -ENOTCONN;
+ return -EBADMSG;
/* See if last packet allocated was not sent */
new_packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
@@ -387,11 +387,7 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len)
switch (hctx->ccid3hctx_state) {
case TFRC_SSTATE_NO_SENT:
- /* if first wasn't pure ack */
- if (len != 0)
- DCCP_CRIT("%s, First packet sent is noted "
- "as a data packet", dccp_role(sk));
- return;
+ /* fall through */
case TFRC_SSTATE_NO_FBACK:
/* t_nom, t_ipi, delta do not change until feedback arrives */
return;