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Date: Fri, 16 Oct 2015 21:57:43 -0700
From: Yuchung Cheng <ycheng@...gle.com>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, Yuchung Cheng <ycheng@...gle.com>,
Neal Cardwell <ncardwell@...gle.com>,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/7] tcp: remove tcp_mark_lost_retrans()
Remove the existing lost retransmit detection because RACK subsumes
it completely. This also stops the overloading the ack_seq field of
the skb control block.
Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/linux/tcp.h | 2 --
net/ipv4/tcp_input.c | 65 ---------------------------------------------------
net/ipv4/tcp_output.c | 6 -----
3 files changed, 73 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 90edef5..8c54863 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -283,8 +283,6 @@ struct tcp_sock {
int lost_cnt_hint;
u32 retransmit_high; /* L-bits may be on up to this seqno */
- u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */
-
u32 prior_ssthresh; /* ssthresh saved at recovery start */
u32 high_seq; /* snd_nxt at onset of congestion */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e177386..5ad08d8 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1048,70 +1048,6 @@ static bool tcp_is_sackblock_valid(struct tcp_sock *tp, bool is_dsack,
return !before(start_seq, end_seq - tp->max_window);
}
-/* Check for lost retransmit. This superb idea is borrowed from "ratehalving".
- * Event "B". Later note: FACK people cheated me again 8), we have to account
- * for reordering! Ugly, but should help.
- *
- * Search retransmitted skbs from write_queue that were sent when snd_nxt was
- * less than what is now known to be received by the other end (derived from
- * highest SACK block). Also calculate the lowest snd_nxt among the remaining
- * retransmitted skbs to avoid some costly processing per ACKs.
- */
-static void tcp_mark_lost_retrans(struct sock *sk, int *flag)
-{
- const struct inet_connection_sock *icsk = inet_csk(sk);
- struct tcp_sock *tp = tcp_sk(sk);
- struct sk_buff *skb;
- int cnt = 0;
- u32 new_low_seq = tp->snd_nxt;
- u32 received_upto = tcp_highest_sack_seq(tp);
-
- if (!tcp_is_fack(tp) || !tp->retrans_out ||
- !after(received_upto, tp->lost_retrans_low) ||
- icsk->icsk_ca_state != TCP_CA_Recovery)
- return;
-
- tcp_for_write_queue(skb, sk) {
- u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
-
- if (skb == tcp_send_head(sk))
- break;
- if (cnt == tp->retrans_out)
- break;
- if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
- continue;
-
- if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS))
- continue;
-
- /* TODO: We would like to get rid of tcp_is_fack(tp) only
- * constraint here (see above) but figuring out that at
- * least tp->reordering SACK blocks reside between ack_seq
- * and received_upto is not easy task to do cheaply with
- * the available datastructures.
- *
- * Whether FACK should check here for tp->reordering segs
- * in-between one could argue for either way (it would be
- * rather simple to implement as we could count fack_count
- * during the walk and do tp->fackets_out - fack_count).
- */
- if (after(received_upto, ack_seq)) {
- TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
- tp->retrans_out -= tcp_skb_pcount(skb);
- *flag |= FLAG_LOST_RETRANS;
- tcp_skb_mark_lost_uncond_verify(tp, skb);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
- } else {
- if (before(ack_seq, new_low_seq))
- new_low_seq = ack_seq;
- cnt += tcp_skb_pcount(skb);
- }
- }
-
- if (tp->retrans_out)
- tp->lost_retrans_low = new_low_seq;
-}
-
static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
struct tcp_sack_block_wire *sp, int num_sacks,
u32 prior_snd_una)
@@ -1838,7 +1774,6 @@ advance_sp:
((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker))
tcp_update_reordering(sk, tp->fackets_out - state->reord, 0);
- tcp_mark_lost_retrans(sk, &state->flag);
tcp_verify_left_out(tp);
out:
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 6e79fcb..49730e5 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2655,8 +2655,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
net_dbg_ratelimited("retrans_out leaked\n");
}
#endif
- if (!tp->retrans_out)
- tp->lost_retrans_low = tp->snd_nxt;
TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS;
tp->retrans_out += tcp_skb_pcount(skb);
@@ -2664,10 +2662,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
if (!tp->retrans_stamp)
tp->retrans_stamp = tcp_skb_timestamp(skb);
- /* snd_nxt is stored to detect loss of retransmitted segment,
- * see tcp_input.c tcp_sacktag_write_queue().
- */
- TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt;
} else if (err != -EBUSY) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL);
}
--
2.6.0.rc2.230.g3dd15c0
--
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