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[TCP]: Abstract tp->highest_sack accessing & point to next skb
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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>
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Ilpo Järvinen authored and David S. Miller committed Jan 28, 2008
1 parent 7201883 commit 6859d49
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Showing 3 changed files with 52 additions and 21 deletions.
35 changes: 34 additions & 1 deletion include/net/tcp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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,
Expand Down
27 changes: 15 additions & 12 deletions net/ipv4/tcp_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1125,7 +1125,7 @@ static void tcp_mark_lost_retrans(struct sock *sk)
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) ||
Expand Down Expand Up @@ -1236,9 +1236,10 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
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;

Expand Down Expand Up @@ -1307,8 +1308,8 @@ static int tcp_sacktag_one(struct sk_buff *skb, struct tcp_sock *tp,
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
Expand All @@ -1330,8 +1331,6 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
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;
Expand All @@ -1358,7 +1357,7 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
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);
}
Expand Down Expand Up @@ -1429,7 +1428,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
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,
Expand Down Expand Up @@ -1552,9 +1551,11 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
&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;
Expand All @@ -1566,8 +1567,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
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);
Expand Down
11 changes: 3 additions & 8 deletions net/ipv4/tcp_output.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -667,7 +667,7 @@ static void tcp_adjust_fackets_out(struct sock *sk, struct sk_buff *skb,
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;
}

Expand Down Expand Up @@ -711,9 +711,6 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
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);
Expand Down Expand Up @@ -1707,9 +1704,7 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
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);
Expand Down Expand Up @@ -2019,7 +2014,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
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)
Expand Down

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