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tcp: new helper for RACK to detect loss 

Create a new helper tcp_rack_detect_loss to prepare the upcoming
RACK reordering timer patch.

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 22:11:31 -08:00 committed by David S. Miller
parent db8da6bb57
commit e636f8b010
3 changed files with 22 additions and 15 deletions
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3
include/net/tcp.h
View File

@ -1863,8 +1863,7 @@ extern int sysctl_tcp_recovery;
/* Use TCP RACK to detect (some) tail and retransmit losses */
#define TCP_RACK_LOST_RETRANS 0x1
extern int tcp_rack_mark_lost(struct sock *sk);
extern void tcp_rack_mark_lost(struct sock *sk);
extern void tcp_rack_advance(struct tcp_sock *tp,
const struct skb_mstamp *xmit_time, u8 sacked);

12
net/ipv4/tcp_input.c
View File

@ -2865,10 +2865,14 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
}
/* Use RACK to detect loss */
if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS &&
tcp_rack_mark_lost(sk)) {
flag |= FLAG_LOST_RETRANS;
*ack_flag |= FLAG_LOST_RETRANS;
if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS) {
u32 prior_retrans = tp->retrans_out;
tcp_rack_mark_lost(sk);
if (prior_retrans > tp->retrans_out) {
flag |= FLAG_LOST_RETRANS;
*ack_flag |= FLAG_LOST_RETRANS;
}
}
/* E. Process state. */

22
net/ipv4/tcp_recovery.c
View File

@ -32,17 +32,11 @@ static void tcp_rack_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
* The current version is only used after recovery starts but can be
* easily extended to detect the first loss.
*/
int tcp_rack_mark_lost(struct sock *sk)
static void tcp_rack_detect_loss(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
u32 reo_wnd, prior_retrans = tp->retrans_out;
if (inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery || !tp->rack.advanced)
return 0;
/* Reset the advanced flag to avoid unnecessary queue scanning */
tp->rack.advanced = 0;
u32 reo_wnd;
/* To be more reordering resilient, allow min_rtt/4 settling delay
* (lower-bounded to 1000uS). We use min_rtt instead of the smoothed
@ -82,7 +76,17 @@ int tcp_rack_mark_lost(struct sock *sk)
break;
}
}
return prior_retrans - tp->retrans_out;
}
void tcp_rack_mark_lost(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery || !tp->rack.advanced)
return;
/* Reset the advanced flag to avoid unnecessary queue scanning */
tp->rack.advanced = 0;
tcp_rack_detect_loss(sk);
}
/* Record the most recently (re)sent time among the (s)acked packets */