1 files changed, 60 insertions, 12 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 8266dfde89c1..8f112d18d450 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -1,6 +1,7 @@
 /*
  *  net/dccp/ccids/ccid3.c
  *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
  *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
  *
@@ -33,11 +34,7 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
-#include "../ccid.h"
 #include "../dccp.h"
-#include "lib/packet_history.h"
-#include "lib/loss_interval.h"
-#include "lib/tfrc.h"
 #include "ccid3.h"
 
 #include <asm/unaligned.h>
@@ -757,6 +754,46 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
         return 0;
 }
 
+/** ccid3_first_li  -  Implements [RFC 3448, 6.3.1]
+ *
+ * Determine the length of the first loss interval via inverse lookup.
+ * Assume that X_recv can be computed by the throughput equation
+ *                  s
+ *      X_recv = --------
+ *               R * fval
+ * Find some p such that f(p) = fval; return 1/p (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
+{
+        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+        u32 x_recv, p, delta;
+        u64 fval;
+
+        if (hcrx->ccid3hcrx_rtt == 0) {
+                DCCP_WARN("No RTT estimate available, using fallback RTT\n");
+                hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
+        }
+
+        delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
+        x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+        if (x_recv == 0) {              /* would also trigger divide-by-zero */
+                DCCP_WARN("X_recv==0\n");
+                if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
+                        DCCP_BUG("stored value of X_recv is zero");
+                        return ~0U;
+                }
+        }
+
+        fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt);
+        fval = scaled_div32(fval, x_recv);
+        p = tfrc_calc_x_reverse_lookup(fval);
+
+        ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
+                       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
+
+        return p == 0 ? ~0U : scaled_div(1, p);
+}
+
 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
@@ -794,6 +831,14 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         /*
          * Handle pending losses and otherwise check for new loss
          */
+        if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) &&
+            tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist,
+                                &hcrx->ccid3hcrx_li_hist,
+                                skb, ndp, ccid3_first_li, sk) ) {
+                do_feedback = CCID3_FBACK_PARAM_CHANGE;
+                goto done_receiving;
+        }
+
         if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
                 goto update_records;
 
@@ -803,7 +848,7 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         if (unlikely(!is_data_packet))
                 goto update_records;
 
-        if (list_empty(&hcrx->ccid3hcrx_li_hist)) {  /* no loss so far: p = 0 */
+        if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
                 const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
                 /*
                  * Empty loss history: no loss so far, hence p stays 0.
@@ -812,6 +857,13 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                  */
                 if (sample != 0)
                         hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
+
+        } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
+                /*
+                 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
+                 * has decreased (resp. p has increased), send feedback now.
+                 */
+                do_feedback = CCID3_FBACK_PARAM_CHANGE;
         }
 
         /*
@@ -823,6 +875,7 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 update_records:
         tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
 
+done_receiving:
         if (do_feedback)
                 ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
 }
@@ -831,10 +884,8 @@ static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
 
-        ccid3_pr_debug("entry\n");
-
         hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
-        INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
+        tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
         return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
 }
 
@@ -844,11 +895,8 @@ static void ccid3_hc_rx_exit(struct sock *sk)
 
         ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
 
-        /* Empty packet history */
         tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
-
-        /* Empty loss interval history */
-        dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
+        tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
 }
 
 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)