[TCP]: Convert highest_sack to sk_buff to allow direct access

It is going to replace the sack fastpath hint quite soon... :-)

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 14 insertions, 2 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index bac17c59b24e..34acee662230 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -332,8 +332,10 @@ struct tcp_sock {
 
         struct tcp_sack_block_wire recv_sack_cache[4];
 
-        u32     highest_sack;   /* Start seq of globally highest revd SACK
-                                 * (validity guaranteed only if sacked_out > 0) */
+        struct sk_buff *highest_sack;   /* highest skb with SACK received
+                                         * (validity guaranteed only if
+                                         * sacked_out > 0)
+                                         */
 
         /* from STCP, retrans queue hinting */
         struct sk_buff* lost_skb_hint;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d893b4480769..0ede804b16d4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1312,6 +1312,16 @@ static inline int tcp_write_queue_empty(struct sock *sk)
         return skb_queue_empty(&sk->sk_write_queue);
 }
 
+/* Start sequence of the highest skb with SACKed bit, valid only if
+ * sacked > 0 or when the caller has ensured validity by itself.
+ */
+static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
+{
+        if (!tp->sacked_out)
+                return tp->snd_una;
+        return TCP_SKB_CB(tp->highest_sack)->seq;
+}
+
 /* /proc */
 enum tcp_seq_states {
         TCP_SEQ_STATE_LISTENING,