[TCP]: Add highest_sack seqno, points to globally highest SACK
It is guaranteed to be valid only when !tp->sacked_out. In most
cases this seqno is available in the last ACK but there is no
guarantee for that. The new fast recovery loss marking algorithm
needs this as entry point.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c6b9f92..c072f88 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -333,6 +333,8 @@
struct tcp_sack_block_wire recv_sack_cache[4];
+ u32 highest_sack; /* Start seq of globally highest revd SACK (valid only in slowpath) */
+
/* from STCP, retrans queue hinting */
struct sk_buff* lost_skb_hint;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f893e90..813f204 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -979,8 +979,10 @@
int i;
int first_sack_index;
- if (!tp->sacked_out)
+ if (!tp->sacked_out) {
tp->fackets_out = 0;
+ tp->highest_sack = tp->snd_una;
+ }
prior_fackets = tp->fackets_out;
/* Check for D-SACK. */
@@ -1217,6 +1219,10 @@
if (fack_count > tp->fackets_out)
tp->fackets_out = fack_count;
+
+ if (after(TCP_SKB_CB(skb)->seq,
+ tp->highest_sack))
+ tp->highest_sack = TCP_SKB_CB(skb)->seq;
} else {
if (dup_sack && (sacked&TCPCB_RETRANS))
reord = min(fack_count, reord);