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Message-Id: <1221933153-11874-12-git-send-email-ilpo.jarvinen@helsinki.fi>
Date: Sat, 20 Sep 2008 20:52:29 +0300
From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org,
"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
Subject: [PATCH net-next 11/15] tcp: reorganize retransmit code loops
Both loops are quite similar, so they can be combined
with little effort. As a result, forward_skb_hint becomes
obsolete as well.
Since non-fwd rexmissions have priority over the fwd-rexmits
(not that this is written to some stone that it should be so,
it's just the current behavior and I currently see no reason
to change that), some trickery had to implemented to keep skb
hint never going past a hole so that we can return there if
that becomes later on necessary.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
---
include/linux/tcp.h | 1 -
include/net/tcp.h | 1 -
net/ipv4/tcp_output.c | 79 ++++++++++++++++++++----------------------------
3 files changed, 33 insertions(+), 48 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index d7637c4..7672906 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -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 */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 9be41c9..10f838e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1041,7 +1041,6 @@ 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;
}
extern void tcp_verify_retransmit_hint(struct tcp_sock *tp,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index fc7bfd6..0234b6f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2034,7 +2034,9 @@ 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;
@@ -2051,7 +2053,8 @@ 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
@@ -2062,65 +2065,49 @@ 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))
- continue;
-
- if (!(sacked & TCPCB_LOST))
- 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))
- inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
- 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);
+ if (fwd_rexmitting) {
+begin_fwd:
+ if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+ break;
+ mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
- tcp_for_write_queue_from(skb, sk) {
- if (skb == tcp_send_head(sk))
- break;
- tp->forward_skb_hint = skb;
+ } 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;
- if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
- break;
+ } else if (!(sacked & TCPCB_LOST)) {
+ if (hole == NULL && !(sacked & TCPCB_SACKED_RETRANS))
+ hole = skb;
+ continue;
- if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
- break;
+ } else {
+ if (icsk->icsk_ca_state != TCP_CA_Loss)
+ mib_idx = LINUX_MIB_TCPFASTRETRANS;
+ else
+ mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
+ }
- if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS)
+ if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
continue;
- /* Ok, retransmit it. */
if (tcp_retransmit_skb(sk, skb)) {
- tp->forward_skb_hint = NULL;
- break;
+ tp->retransmit_skb_hint = NULL;
+ return;
}
+ NET_INC_STATS_BH(sock_net(sk), mib_idx);
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);
}
}
--
1.5.2.2
--
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