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[TCP]: Extract DSACK detection code from tcp_sacktag_write_queue(). 

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2007-06-18 22:43:06 -07:00 committed by David S. Miller
parent 19b2b48658
commit d06e021d71
1 changed files with 36 additions and 20 deletions
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56
net/ipv4/tcp_input.c
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@ -960,6 +960,39 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
* Both of these heuristics are not used in Loss state, when we cannot
* account for retransmits accurately.
*/
static int tcp_check_dsack(struct tcp_sock *tp, struct sk_buff *ack_skb,
struct tcp_sack_block_wire *sp, int num_sacks,
u32 prior_snd_una)
{
u32 start_seq_0 = ntohl(get_unaligned(&sp[0].start_seq));
u32 end_seq_0 = ntohl(get_unaligned(&sp[0].end_seq));
int dup_sack = 0;
if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
} else if (num_sacks > 1) {
u32 end_seq_1 = ntohl(get_unaligned(&sp[1].end_seq));
u32 start_seq_1 = ntohl(get_unaligned(&sp[1].start_seq));
if (!after(end_seq_0, end_seq_1) &&
!before(start_seq_0, start_seq_1)) {
dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
}
}
/* D-SACK for already forgotten data... Do dumb counting. */
if (dup_sack &&
!after(end_seq_0, prior_snd_una) &&
after(end_seq_0, tp->undo_marker))
tp->undo_retrans--;
return dup_sack;
}
static int
tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una)
{
@ -985,27 +1018,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
prior_fackets = tp->fackets_out;
/* Check for D-SACK. */
if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
found_dup_sack = tcp_check_dsack(tp, ack_skb, sp,
num_sacks, prior_snd_una);
if (found_dup_sack)
flag |= FLAG_DSACKING_ACK;
found_dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
} else if (num_sacks > 1 &&
!after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) &&
!before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) {
flag |= FLAG_DSACKING_ACK;
found_dup_sack = 1;
tp->rx_opt.sack_ok |= 4;
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
}
/* D-SACK for already forgotten data...
* Do dumb counting. */
if (found_dup_sack &&
!after(ntohl(sp[0].end_seq), prior_snd_una) &&
after(ntohl(sp[0].end_seq), tp->undo_marker))
tp->undo_retrans--;
/* Eliminate too old ACKs, but take into
* account more or less fresh ones, they can