[PATCH 2/5] Implement loss counting on TFRC-SP receiver

[Ivo Calado <ivocalado@embedded.ufcg.edu.br>]

Implement loss counting on TFRC-SP receiver. Consider transmission's hole size as loss count.

Changes:
 - Adds field li_losses to tfrc_loss_interval to track loss count per interval
 - Adds field num_losses to tfrc_rx_hist, used to store loss count per loss event
 - Adds dccp_loss_count function to net/dccp/dccp.h, responsible for loss count using sequence numbers

Signed-off-by: Ivo Calado, Erivaldo Xavier, Leandro Sales <ivocalado@embedded.ufcg.edu.br>, <desadoc@gmail.com>, <leandroal@gmail.com>

Index: dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.c
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/loss_interval_sp.c	2009-09-03 22:58:17.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.c	2009-09-03 23:00:24.000000000 -0300
@@ -187,6 +187,7 @@
 		s64 len = dccp_delta_seqno(cur->li_seqno, cong_evt_seqno);
 		if ((len <= 0) ||
 		    (!tfrc_lh_closed_check(cur, cong_evt->tfrchrx_ccval))) {
+			cur->li_losses += rh->num_losses;
 			return false;
 		}
 
@@ -204,6 +205,7 @@
 	cur->li_seqno	  = cong_evt_seqno;
 	cur->li_ccval	  = cong_evt->tfrchrx_ccval;
 	cur->li_is_closed = false;
+	cur->li_losses	  = rh->num_losses;
 
 	if (++lh->counter = 1)
 		lh->i_mean = cur->li_length = (*calc_first_li)(sk);
Index: dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.h
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/loss_interval_sp.h	2009-09-03 22:58:17.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.h	2009-09-03 23:00:24.000000000 -0300
@@ -30,12 +30,14 @@
  *  @li_ccval:		The CCVal belonging to @li_seqno
  *  @li_is_closed:	Whether @li_seqno is older than 1 RTT
  *  @li_length:		Loss interval sequence length
+ *  @li_losses: 	Number of losses counted on this interval
  */
 struct tfrc_loss_interval {
 	u64		 li_seqno:48,
 			 li_ccval:4,
 			 li_is_closed:1;
 	u32		 li_length;
+	u32		 li_losses;
 };
 
 /*
Index: dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.c
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/packet_history_sp.c	2009-09-03 22:58:17.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.c	2009-09-03 23:00:24.000000000 -0300
@@ -244,6 +244,7 @@
 		h->loss_count = 3;
 		tfrc_sp_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3),
 					       skb, n3);
+		h->num_losses = dccp_loss_count(s2, s3, n3);
 		return 1;
 	}
 
@@ -257,6 +258,7 @@
 		tfrc_sp_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2),
 					       skb, n3);
 		h->loss_count = 3;
+		h->num_losses = dccp_loss_count(s1, s3, n3);
 		return 1;
 	}
 
@@ -293,6 +295,7 @@
 	h->loss_start = tfrc_rx_hist_index(h, 3);
 	tfrc_sp_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3);
 	h->loss_count = 3;
+	h->num_losses = dccp_loss_count(s0, s3, n3);
 
 	return 1;
 }
Index: dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.h
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/packet_history_sp.h	2009-09-03 22:58:17.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.h	2009-09-03 22:58:29.000000000 -0300
@@ -113,6 +113,7 @@
 	u32			  packet_size,
 				  bytes_recvd;
 	ktime_t			  bytes_start;
+	u8			  num_losses;
 };
 
 /*
Index: dccp_tree_work4/net/dccp/dccp.h
=================================--- dccp_tree_work4.orig/net/dccp/dccp.h	2009-09-03 22:58:17.000000000 -0300
+++ dccp_tree_work4/net/dccp/dccp.h	2009-09-03 22:58:29.000000000 -0300
@@ -168,6 +168,21 @@
 	return (u64)delta <= ndp + 1;
 }
 
+static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
+{
+	s64 delta, count;
+
+	delta = dccp_delta_seqno(s1, s2);
+	WARN_ON(delta < 0);
+
+	count = ndp + 1;
+	count -= delta;
+
+	count = (count > 0) ? count : 0;
+
+	return (u64) count;
+}
+
 enum {
 	DCCP_MIB_NUM = 0,
 	DCCP_MIB_ACTIVEOPENS,			/* ActiveOpens */