From: Gerrit Renker Date: Mon, 27 Nov 2006 14:26:57 +0000 (-0200) Subject: [DCCP] ccid3: Avoid congestion control on zero-sized data packets X-Git-Tag: v2.6.20-rc1~34^2~40^2~146 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=da335baf9e788edfb00ee3b96f7b9526b6b2f8a9;p=linux-2.6 [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 Signed-off-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 2745d835f0..62c304200e 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;