dccp ccid-2: prevent cwnd > Sequence Window

[pandora-kernel.git] / net / dccp / ccids / ccid2.c

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index b51cc92..9dbc4d8 100644 (file)
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -85,7 +85,6 @@ static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 
 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
 {
-       struct dccp_sock *dp = dccp_sk(sk);
        u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2);
 
        /*
@@ -98,14 +97,15 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
                DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
                val = max_ratio;
        }
-       if (val > DCCPF_ACK_RATIO_MAX)
-               val = DCCPF_ACK_RATIO_MAX;
-
-       if (val == dp->dccps_l_ack_ratio)
-               return;
+       dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
+                                  min_t(u32, val, DCCPF_ACK_RATIO_MAX));
+}
 
-       ccid2_pr_debug("changing local ack ratio to %u\n", val);
-       dp->dccps_l_ack_ratio = val;
+static void ccid2_change_l_seq_window(struct sock *sk, u64 val)
+{
+       dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW,
+                                  clamp_val(val, DCCPF_SEQ_WMIN,
+                                                 DCCPF_SEQ_WMAX));
 }
 
 static void ccid2_hc_tx_rto_expire(unsigned long data)
@@ -405,17 +405,37 @@ static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
                          unsigned int *maxincr)
 {
        struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-
-       if (hc->tx_cwnd < hc->tx_ssthresh) {
-               if (*maxincr > 0 && ++hc->tx_packets_acked == 2) {
+       struct dccp_sock *dp = dccp_sk(sk);
+       int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
+
+       if (hc->tx_cwnd < dp->dccps_l_seq_win &&
+           r_seq_used < dp->dccps_r_seq_win) {
+               if (hc->tx_cwnd < hc->tx_ssthresh) {
+                       if (*maxincr > 0 && ++hc->tx_packets_acked == 2) {
+                               hc->tx_cwnd += 1;
+                               *maxincr    -= 1;
+                               hc->tx_packets_acked = 0;
+                       }
+               } else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
                        hc->tx_cwnd += 1;
-                       *maxincr    -= 1;
                        hc->tx_packets_acked = 0;
                }
-       } else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
-                       hc->tx_cwnd += 1;
-                       hc->tx_packets_acked = 0;
        }
+
+       /*
+        * Adjust the local sequence window and the ack ratio to allow about
+        * 5 times the number of packets in the network (RFC 4340 7.5.2)
+        */
+       if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
+               ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
+       else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
+               ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
+
+       if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
+               ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
+       else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
+               ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
+
        /*
         * FIXME: RTT is sampled several times per acknowledgment (for each
         * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).