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tcp: reorganize retransmit code loops

Browse source 
Both loops are quite similar, so they can be combined
with little effort. As a result, forward_skb_hint becomes
obsolete as well.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilpo Järvinen 2008-09-20 21:24:21 -07:00 committed by David S. Miller
parent 08ebd1721a
commit 0e1c54c2a4
3 changed files with 33 additions and 48 deletions
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1
include/linux/tcp.h
View file

@ -342,7 +342,6 @@ struct tcp_sock {
struct sk_buff* lost_skb_hint;
struct sk_buff *scoreboard_skb_hint;
struct sk_buff *retransmit_skb_hint;
struct sk_buff *forward_skb_hint;
struct sk_buff_head out_of_order_queue; /* Out of order segments go here */

1
include/net/tcp.h
View file

@ -1042,7 +1042,6 @@ static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
tp->lost_skb_hint = NULL;
tp->scoreboard_skb_hint = NULL;
tp->retransmit_skb_hint = NULL;
tp->forward_skb_hint = NULL;
}
/* MD5 Signature */

79
net/ipv4/tcp_output.c
View file

@ -2032,7 +2032,9 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
const struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
struct sk_buff *hole = NULL;
int mib_idx;
int fwd_rexmitting = 0;
if (!tp->lost_out)
tp->retransmit_high = tp->snd_una;
@ -2049,7 +2051,8 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
if (skb == tcp_send_head(sk))
break;
/* we could do better than to assign each time */
tp->retransmit_skb_hint = skb;
if (hole == NULL)
tp->retransmit_skb_hint = skb;
/* Assume this retransmit will generate
* only one packet for congestion window
@ -2060,22 +2063,43 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
*/
if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
return;
if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high))
break;
if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
if (fwd_rexmitting) {
begin_fwd:
if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
break;
mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
} else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) {
if (!tcp_can_forward_retransmit(sk))
break;
/* Backtrack if necessary to non-L'ed skb */
if (hole != NULL) {
skb = hole;
hole = NULL;
}
fwd_rexmitting = 1;
goto begin_fwd;
} else if (!(sacked & TCPCB_LOST)) {
if (hole == NULL && !(sacked & TCPCB_SACKED_RETRANS))
hole = skb;
continue;
if (!(sacked & TCPCB_LOST))
} else {
if (icsk->icsk_ca_state != TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPFASTRETRANS;
else
mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
}
if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
continue;
if (tcp_retransmit_skb(sk, skb)) {
tp->retransmit_skb_hint = NULL;
return;
}
if (icsk->icsk_ca_state != TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPFASTRETRANS;
else
mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
NET_INC_STATS_BH(sock_net(sk), mib_idx);
if (skb == tcp_write_queue_head(sk))
@ -2083,43 +2107,6 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
inet_csk(sk)->icsk_rto,
TCP_RTO_MAX);
}
/* OK, demanded retransmission is finished. */
if (!tcp_can_forward_retransmit(sk))
return;
if (tp->forward_skb_hint)
skb = tp->forward_skb_hint;
else
skb = tcp_write_queue_head(sk);
tcp_for_write_queue_from(skb, sk) {
if (skb == tcp_send_head(sk))
break;
tp->forward_skb_hint = skb;
if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
break;
if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
break;
if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS)
continue;
/* Ok, retransmit it. */
if (tcp_retransmit_skb(sk, skb)) {
tp->forward_skb_hint = NULL;
break;
}
if (skb == tcp_write_queue_head(sk))
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
inet_csk(sk)->icsk_rto,
TCP_RTO_MAX);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFORWARDRETRANS);
}
}
/* Send a fin. The caller locks the socket for us. This cannot be