[TCP]: Abstract tp->highest_sack accessing & point to next skb

Pointing to the next skb is necessary to avoid referencing
already SACKed skbs which will soon be on a separate list.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 1 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6e392babda4a..5ec1cacca8a1 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1267,8 +1267,12 @@ static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb
         __tcp_add_write_queue_tail(sk, skb);
 
         /* Queue it, remembering where we must start sending. */
-        if (sk->sk_send_head == NULL)
+        if (sk->sk_send_head == NULL) {
                 sk->sk_send_head = skb;
+
+                if (tcp_sk(sk)->highest_sack == NULL)
+                        tcp_sk(sk)->highest_sack = skb;
+        }
 }
 
 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
@@ -1318,9 +1322,38 @@ static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
 {
         if (!tp->sacked_out)
                 return tp->snd_una;
+
+        if (tp->highest_sack == NULL)
+                return tp->snd_nxt;
+
         return TCP_SKB_CB(tp->highest_sack)->seq;
 }
 
+static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
+{
+        tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
+                                                tcp_write_queue_next(sk, skb);
+}
+
+static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
+{
+        return tcp_sk(sk)->highest_sack;
+}
+
+static inline void tcp_highest_sack_reset(struct sock *sk)
+{
+        tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
+}
+
+/* Called when old skb is about to be deleted (to be combined with new skb) */
+static inline void tcp_highest_sack_combine(struct sock *sk,
+                                            struct sk_buff *old,
+                                            struct sk_buff *new)
+{
+        if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
+                tcp_sk(sk)->highest_sack = new;
+}
+
 /* /proc */
 enum tcp_seq_states {
         TCP_SEQ_STATE_LISTENING,