1 files changed, 14 insertions, 29 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 04b183548aa8..8e64d9665a21 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -556,8 +556,8 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk,
                          * would bring X down to s/t_mbi. That is why we return
                          * X_recv according to rfc3448bis-06 for the moment.
                          */
-                        u32 rtt = hcrx->rtt ? : DCCP_FALLBACK_RTT,
-                            s   = tfrc_rx_hist_packet_size(&hcrx->hist);
+                        u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
+                            rtt = tfrc_rx_hist_rtt(&hcrx->hist);
 
                         hcrx->x_recv = scaled_div32(s, 2 * rtt);
                         break;
@@ -576,6 +576,11 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk,
                         break;
                 /* fall through */
         case CCID3_FBACK_PERIODIC:
+                /*
+                 * FIXME: check if delta is less than or equal to 1 RTT using
+                 * the receiver RTT sample. This is described in Errata 610/611
+                 * of RFC 4342 which reference section 6.2 of RFC 3448.
+                 */
                 delta = ktime_us_delta(now, hcrx->tstamp_last_feedback);
                 if (delta <= 0)
                         DCCP_BUG("delta (%ld) <= 0", (long)delta);
@@ -633,8 +638,8 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
 static u32 ccid3_first_li(struct sock *sk)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
-        u32 x_recv, p, delta,
-            s = tfrc_rx_hist_packet_size(&hcrx->hist);
+        u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
+            rtt = tfrc_rx_hist_rtt(&hcrx->hist), x_recv, p, delta;
         u64 fval;
 
         /*
@@ -645,11 +650,6 @@ static u32 ccid3_first_li(struct sock *sk)
         if (unlikely(hcrx->feedback == CCID3_FBACK_NONE))
                 return 5;
 
-        if (hcrx->rtt == 0) {
-                DCCP_WARN("No RTT estimate available, using fallback RTT\n");
-                hcrx->rtt = DCCP_FALLBACK_RTT;
-        }
-
         delta = ktime_to_us(net_timedelta(hcrx->tstamp_last_feedback));
         x_recv = scaled_div32(hcrx->hist.bytes_recvd, delta);
         if (x_recv == 0) {              /* would also trigger divide-by-zero */
@@ -661,7 +661,7 @@ static u32 ccid3_first_li(struct sock *sk)
                 x_recv = hcrx->x_recv;
         }
 
-        fval = scaled_div32(scaled_div(s, hcrx->rtt), x_recv);
+        fval = scaled_div32(scaled_div(s, rtt), x_recv);
         p = tfrc_calc_x_reverse_lookup(fval);
 
         ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
@@ -696,25 +696,10 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 return; /* done receiving */
 
         /*
-         * Handle data packets: RTT sampling and monitoring p
-         */
-        if (unlikely(!is_data_packet))
-                goto update_records;
-
-        if (!tfrc_lh_is_initialised(&hcrx->li_hist)) {
-                const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->hist, skb);
-                /*
-                 * Empty loss history: no loss so far, hence p stays 0.
-                 * Sample RTT values, since an RTT estimate is required for the
-                 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
-                 */
-                if (sample != 0)
-                        hcrx->rtt = tfrc_ewma(hcrx->rtt, sample, 9);
-        }
-        /*
          * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
          */
-        if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->last_counter) > 3)
+        if (is_data_packet &&
+            SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->last_counter) > 3)
                 do_feedback = CCID3_FBACK_PERIODIC;
 
 update_records:
@@ -744,7 +729,7 @@ static void ccid3_hc_rx_exit(struct sock *sk)
 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
 {
         info->tcpi_options  |= TCPI_OPT_TIMESTAMPS;
-        info->tcpi_rcv_rtt  = ccid3_hc_rx_sk(sk)->rtt;
+        info->tcpi_rcv_rtt  = tfrc_rx_hist_rtt(&ccid3_hc_rx_sk(sk)->hist);
 }
 
 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
@@ -759,7 +744,7 @@ static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
                 if (len < sizeof(rx_info))
                         return -EINVAL;
                 rx_info.tfrcrx_x_recv = hcrx->x_recv;
-                rx_info.tfrcrx_rtt    = hcrx->rtt;
+                rx_info.tfrcrx_rtt    = tfrc_rx_hist_rtt(&hcrx->hist);
                 rx_info.tfrcrx_p      = tfrc_invert_loss_event_rate(hcrx->p_inverse);
                 len = sizeof(rx_info);
                 val = &rx_info;