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, 2 insertions, 22 deletions

diff --git a/net/dccp/ccids/lib/packet_history.h b/net/dccp/ccids/lib/packet_history.h
index 6976156..461cc91 100644
--- a/net/dccp/ccids/lib/packet_history.h
+++ b/net/dccp/ccids/lib/packet_history.h
@@ -118,30 +118,10 @@ static inline struct tfrc_rx_hist_entry *
 	return h->ring[h->loss_start];
 }
 
-/* initialise loss detection and disable RTT sampling */
-static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h)
-{
-	h->loss_count = 1;
-}
-
 /* indicate whether previously a packet was detected missing */
-static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
-{
-	return h->loss_count;
-}
-
-/* any data packets missing between last reception and skb ? */
-static inline int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h,
-						  const struct sk_buff *skb,
-						  u32 ndp)
+static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
 {
-	int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno,
-				     DCCP_SKB_CB(skb)->dccpd_seq);
-
-	if (delta > 1 && ndp < delta)
-		tfrc_rx_hist_loss_indicated(h);
-
-	return tfrc_rx_hist_loss_pending(h);
+	return h->loss_count > 0;
 }
 
 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,