diff options
| -rw-r--r-- | net/dccp/ccids/ccid2.c | 39 |
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) |