[CCID3]: Implement rfc3448bis changes to feedback reception
This implements the algorithm to update the allowed sending rate X upon
receiving feedback packets, as described in draft rfc3448bis, 4.2/4.3.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-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/ccid3.c b/net/dccp/ccids/ccid3.c
index a93a556..1156fef 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -429,40 +429,46 @@
if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */
hctx->ccid3hctx_p = 0;
else /* can not exceed 100% */
- hctx->ccid3hctx_p = 1000000 / pinv;
+ hctx->ccid3hctx_p = scaled_div(1, pinv);
/*
* Validate new RTT sample and update moving average
*/
r_sample = dccp_sample_rtt(sk, r_sample);
hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);
-
+ /*
+ * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
+ */
if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
- /*
- * Larger Initial Windows [RFC 4342, sec. 5]
- */
- hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
- hctx->ccid3hctx_t_ld = now;
-
- ccid3_update_send_interval(hctx);
-
- ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
- "R_sample=%uus, X=%u\n", dccp_role(sk),
- sk, hctx->ccid3hctx_s,
- dccp_sk(sk)->dccps_mss_cache, r_sample,
- (unsigned)(hctx->ccid3hctx_x >> 6));
-
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
- } else {
- /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
- if (hctx->ccid3hctx_p > 0)
- hctx->ccid3hctx_x_calc =
+ if (hctx->ccid3hctx_t_rto == 0) {
+ /*
+ * Initial feedback packet: Larger Initial Windows (4.2)
+ */
+ hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
+ hctx->ccid3hctx_t_ld = now;
+
+ ccid3_update_send_interval(hctx);
+
+ goto done_computing_x;
+ } else if (hctx->ccid3hctx_p == 0) {
+ /*
+ * First feedback after nofeedback timer expiry (4.3)
+ */
+ goto done_computing_x;
+ }
+ }
+
+ /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
+ if (hctx->ccid3hctx_p > 0)
+ hctx->ccid3hctx_x_calc =
tfrc_calc_x(hctx->ccid3hctx_s,
hctx->ccid3hctx_rtt,
hctx->ccid3hctx_p);
- ccid3_hc_tx_update_x(sk, &now);
+ ccid3_hc_tx_update_x(sk, &now);
- ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
+done_computing_x:
+ ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
"p=%u, X_calc=%u, X_recv=%u, X=%u\n",
dccp_role(sk),
sk, hctx->ccid3hctx_rtt, r_sample,
@@ -470,7 +476,6 @@
hctx->ccid3hctx_x_calc,
(unsigned)(hctx->ccid3hctx_x_recv >> 6),
(unsigned)(hctx->ccid3hctx_x >> 6));
- }
/* unschedule no feedback timer */
sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);