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tcp: new helper function for RACK loss detection 

Create a new helper tcp_rack_mark_skb_lost to prepare the
upcoming RACK reordering timer support.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2017-01-12 22:11:30 -08:00 committed by David S. Miller
parent 7410191afc
commit db8da6bb57
1 changed files with 14 additions and 7 deletions
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21
net/ipv4/tcp_recovery.c
View File

@ -3,6 +3,19 @@
int sysctl_tcp_recovery __read_mostly = TCP_RACK_LOST_RETRANS;
static void tcp_rack_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
tcp_skb_mark_lost_uncond_verify(tp, skb);
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
/* Account for retransmits that are lost again */
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= tcp_skb_pcount(skb);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
}
}
/* Marks a packet lost, if some packet sent later has been (s)acked.
* The underlying idea is similar to the traditional dupthresh and FACK
* but they look at different metrics:
@ -61,13 +74,7 @@ int tcp_rack_mark_lost(struct sock *sk)
continue;
/* skb is lost if packet sent later is sacked */
tcp_skb_mark_lost_uncond_verify(tp, skb);
if (scb->sacked & TCPCB_SACKED_RETRANS) {
scb->sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= tcp_skb_pcount(skb);
NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPLOSTRETRANSMIT);
}
tcp_rack_mark_skb_lost(sk, skb);
} else if (!(scb->sacked & TCPCB_RETRANS)) {
/* Original data are sent sequentially so stop early
* b/c the rest are all sent after rack_sent