dccp ccid-3: Fix a loss detection bug

This fixes a bug in the logic of the TFRC loss detection:
 * new_loss_indicated() should not be called while a loss is pending;
 * but the code allows this;
 * thus, for two subsequent gaps in the sequence space, when loss_count
   has not yet reached NDUPACK=3, the loss_count is falsely reduced to 1.

To avoid further and similar problems, all loss handling and loss detection is
now done inside tfrc_rx_hist_handle_loss(), using an appropriate routine to
track new losses.

Further changes:
----------------
 * added a reminder that no RX history operations should be performed when
   rx_handle_loss() has identified a (new) loss, since the function takes
   care of packet reordering during loss detection;
 * made tfrc_rx_hist_loss_pending() bool (thanks to an earlier suggestion
   by Arnaldo);		 
 * removed unused functions.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

1 files changed, 5 insertions, 7 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 523db262c18f..f6756e0c9e69 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -825,18 +825,16 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         }
 
         /*
-         * Handle pending losses and otherwise check for new loss
+         * Perform loss detection and handle pending losses
          */
-        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) ) {
+        if (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;
+        if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist))
+                return; /* done receiving */
 
         /*
          * Handle data packets: RTT sampling and monitoring p