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Diffstat (limited to 'net/dccp/ccids')
-rw-r--r--net/dccp/ccids/ccid2.c39
1 files changed, 21 insertions, 18 deletions
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index f18235e8ce8..ef19fb83429 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -143,32 +143,30 @@ 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)->ccid2hctx_cwnd, 2);
+
/*
- * XXX I don't really agree with val != 2. If cwnd is 1, ack ratio
- * should be 1... it shouldn't be allowed to become 2.
- * -sorbo.
+ * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
+ * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
+ * acceptable since this causes starvation/deadlock whenever cwnd < 2.
+ * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
*/
- if (val != 2) {
- const struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
- int max = hctx->ccid2hctx_cwnd / 2;
-
- /* round up */
- if (hctx->ccid2hctx_cwnd & 1)
- max++;
-
- if (val > max)
- val = max;
+ if (val == 0 || val > max_ratio) {
+ DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
+ val = max_ratio;
}
if (val > 0xFFFF) /* RFC 4340, 11.3 */
val = 0xFFFF;
+ if (val == dp->dccps_l_ack_ratio)
+ return;
+
ccid2_pr_debug("changing local ack ratio to %u\n", val);
dp->dccps_l_ack_ratio = val;
}
static void ccid2_change_cwnd(struct ccid2_hc_tx_sock *hctx, u32 val)
{
- /* XXX do we need to change ack ratio? */
hctx->ccid2hctx_cwnd = val? : 1;
ccid2_pr_debug("changed cwnd to %u\n", hctx->ccid2hctx_cwnd);
}
@@ -519,9 +517,10 @@ static void ccid2_hc_tx_dec_pipe(struct sock *sk)
ccid2_hc_tx_kill_rto_timer(sk);
}
-static void ccid2_congestion_event(struct ccid2_hc_tx_sock *hctx,
- struct ccid2_seq *seqp)
+static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
return;
@@ -533,6 +532,10 @@ static void ccid2_congestion_event(struct ccid2_hc_tx_sock *hctx,
hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd;
if (hctx->ccid2hctx_ssthresh < 2)
hctx->ccid2hctx_ssthresh = 2;
+
+ /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
+ if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
+ ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
}
static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
@@ -648,7 +651,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
!seqp->ccid2s_acked) {
if (state ==
DCCP_ACKVEC_STATE_ECN_MARKED) {
- ccid2_congestion_event(hctx,
+ ccid2_congestion_event(sk,
seqp);
} else
ccid2_new_ack(sk, seqp,
@@ -713,7 +716,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
* order to detect multiple congestion events in
* one ack vector.
*/
- ccid2_congestion_event(hctx, seqp);
+ ccid2_congestion_event(sk, seqp);
ccid2_hc_tx_dec_pipe(sk);
}
if (seqp == hctx->ccid2hctx_seqt)