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-rw-r--r--net/dccp/ccids/ccid2.c84
1 files changed, 66 insertions, 18 deletions
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 0462040fc818..67164bb6ae4d 100644
--- 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 +97,33 @@ 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;
+ dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
+ min_t(u32, val, DCCPF_ACK_RATIO_MAX));
+}
- if (val == dp->dccps_l_ack_ratio)
- return;
+static void ccid2_check_l_ack_ratio(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
- ccid2_pr_debug("changing local ack ratio to %u\n", val);
- dp->dccps_l_ack_ratio = val;
+ /*
+ * After a loss, idle period, application limited period, or RTO we
+ * need to check that the ack ratio is still less than the congestion
+ * window. Otherwise, we will send an entire congestion window of
+ * packets and got no response because we haven't sent ack ratio
+ * packets yet.
+ * If the ack ratio does need to be reduced, we reduce it to half of
+ * the congestion window (or 1 if that's zero) instead of to the
+ * congestion window. This prevents problems if one ack is lost.
+ */
+ if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd)
+ ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U);
+}
+
+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)
@@ -187,6 +205,8 @@ static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now)
}
hc->tx_cwnd_used = 0;
hc->tx_cwnd_stamp = now;
+
+ ccid2_check_l_ack_ratio(sk);
}
/* This borrows the code of tcp_cwnd_restart() */
@@ -205,6 +225,8 @@ static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
hc->tx_cwnd_stamp = now;
hc->tx_cwnd_used = 0;
+
+ ccid2_check_l_ack_ratio(sk);
}
static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
@@ -405,17 +427,37 @@ 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).
@@ -441,9 +483,7 @@ static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U;
hc->tx_ssthresh = max(hc->tx_cwnd, 2U);
- /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
- if (dccp_sk(sk)->dccps_l_ack_ratio > hc->tx_cwnd)
- ccid2_change_l_ack_ratio(sk, hc->tx_cwnd);
+ ccid2_check_l_ack_ratio(sk);
}
static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
@@ -494,8 +534,16 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
if (hc->tx_rpdupack >= NUMDUPACK) {
hc->tx_rpdupack = -1; /* XXX lame */
hc->tx_rpseq = 0;
-
+#ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
+ /*
+ * FIXME: Ack Congestion Control is broken; in
+ * the current state instabilities occurred with
+ * Ack Ratios greater than 1; causing hang-ups
+ * and long RTO timeouts. This needs to be fixed
+ * before opening up dynamic changes. -- gerrit
+ */
ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
+#endif
}
}
}
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