[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>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6e392ba..5ec1cac 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1267,8 +1267,12 @@
__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 @@
{
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,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 263c536..bc2d5f7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1125,7 +1125,7 @@
struct sk_buff *skb;
int cnt = 0;
u32 new_low_seq = tp->snd_nxt;
- u32 received_upto = TCP_SKB_CB(tp->highest_sack)->end_seq;
+ u32 received_upto = tcp_highest_sack_seq(tp);
if (!tcp_is_fack(tp) || !tp->retrans_out ||
!after(received_upto, tp->lost_retrans_low) ||
@@ -1236,9 +1236,10 @@
return in_sack;
}
-static int tcp_sacktag_one(struct sk_buff *skb, struct tcp_sock *tp,
+static int tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
int *reord, int dup_sack, int fack_count)
{
+ struct tcp_sock *tp = tcp_sk(sk);
u8 sacked = TCP_SKB_CB(skb)->sacked;
int flag = 0;
@@ -1307,8 +1308,8 @@
if (fack_count > tp->fackets_out)
tp->fackets_out = fack_count;
- if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
- tp->highest_sack = skb;
+ if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+ tcp_advance_highest_sack(sk, skb);
}
/* D-SACK. We can detect redundant retransmission in S|R and plain R
@@ -1330,8 +1331,6 @@
int dup_sack_in, int *fack_count,
int *reord, int *flag)
{
- struct tcp_sock *tp = tcp_sk(sk);
-
tcp_for_write_queue_from(skb, sk) {
int in_sack = 0;
int dup_sack = dup_sack_in;
@@ -1358,7 +1357,7 @@
break;
if (in_sack)
- *flag |= tcp_sacktag_one(skb, tp, reord, dup_sack, *fack_count);
+ *flag |= tcp_sacktag_one(skb, sk, reord, dup_sack, *fack_count);
*fack_count += tcp_skb_pcount(skb);
}
@@ -1429,7 +1428,7 @@
if (!tp->sacked_out) {
if (WARN_ON(tp->fackets_out))
tp->fackets_out = 0;
- tp->highest_sack = tcp_write_queue_head(sk);
+ tcp_highest_sack_reset(sk);
}
found_dup_sack = tcp_check_dsack(tp, ack_skb, sp_wire,
@@ -1552,9 +1551,11 @@
&fack_count, &reord, &flag);
/* ...tail remains todo... */
- if (TCP_SKB_CB(tp->highest_sack)->end_seq == cache->end_seq) {
+ if (tcp_highest_sack_seq(tp) == cache->end_seq) {
/* ...but better entrypoint exists! */
- skb = tcp_write_queue_next(sk, tp->highest_sack);
+ skb = tcp_highest_sack(sk);
+ if (skb == NULL)
+ break;
fack_count = tp->fackets_out;
cache++;
goto walk;
@@ -1566,8 +1567,10 @@
continue;
}
- if (tp->sacked_out && !before(start_seq, tcp_highest_sack_seq(tp))) {
- skb = tcp_write_queue_next(sk, tp->highest_sack);
+ if (!before(start_seq, tcp_highest_sack_seq(tp))) {
+ skb = tcp_highest_sack(sk);
+ if (skb == NULL)
+ break;
fack_count = tp->fackets_out;
}
skb = tcp_sacktag_skip(skb, sk, start_seq);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7d8583a..9a985b5 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -667,7 +667,7 @@
if (!tp->sacked_out || tcp_is_reno(tp))
return;
- if (!before(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq))
+ if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq))
tp->fackets_out -= decr;
}
@@ -711,9 +711,6 @@
TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
- if (tcp_is_sack(tp) && tp->sacked_out && (skb == tp->highest_sack))
- tp->highest_sack = buff;
-
/* PSH and FIN should only be set in the second packet. */
flags = TCP_SKB_CB(skb)->flags;
TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH);
@@ -1707,9 +1704,7 @@
BUG_ON(tcp_skb_pcount(skb) != 1 ||
tcp_skb_pcount(next_skb) != 1);
- if (WARN_ON(tcp_is_sack(tp) && tp->sacked_out &&
- (next_skb == tp->highest_sack)))
- return;
+ tcp_highest_sack_combine(sk, next_skb, skb);
/* Ok. We will be able to collapse the packet. */
tcp_unlink_write_queue(next_skb, sk);
@@ -2019,7 +2014,7 @@
break;
tp->forward_skb_hint = skb;
- if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+ if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
break;
if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
