[CCID2]: Larger initial windows also for CCID2

RFC 4341, sec. 5 states that "The cwnd parameter is initialized to at most
four packets for new connections, following the rules from [RFC3390]", which
is implemented by this patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index ef19fb8342992a050f229c45901a3bd16e9d9917..9c5b6c73f7c98122b9140a59674aa0efdf3cffbb 100644 (file)
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -741,15 +741,25 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
 {
        struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
+       struct dccp_sock *dp = dccp_sk(sk);
+       u32 max_ratio;
 
-       ccid2_change_cwnd(hctx, 1);
-       /* Initialize ssthresh to infinity.  This means that we will exit the
-        * initial slow-start after the first packet loss.  This is what we
-        * want.
-        */
+       /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
        hctx->ccid2hctx_ssthresh  = ~0;
        hctx->ccid2hctx_numdupack = 3;
 
+       /*
+        * RFC 4341, 5: "The cwnd parameter is initialized to at most four
+        * packets for new connections, following the rules from [RFC3390]".
+        * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
+        */
+       hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache));
+
+       /* Make sure that Ack Ratio is enabled and within bounds. */
+       max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
+       if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
+               dp->dccps_l_ack_ratio = max_ratio;
+
        /* XXX init ~ to window size... */
        if (ccid2_hc_tx_alloc_seq(hctx))
                return -ENOMEM;