[PATCH net-next 07/17] tcp: remove redundant code from tcp_mark_lost_retrans
From: Ilpo Järvinen <hidden>
Date: 2009-02-28 14:44:47
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
From: Ilpo Järvinen <redacted> Arnd Hannemann [off-list ref] noticed and was puzzled by the fact that !tcp_is_fack(tp) leads to early return near the beginning and the later on tcp_is_fack(tp) was still used in an if condition. The later check was a left-over from RFC3517 SACK stuff (== !tcp_is_fack(tp) behavior nowadays) as there wasn't clear way how to handle this particular check cheaply in the spirit of RFC3517 (using only SACK blocks, not holes + SACK blocks as with FACK). I sort of left it there as a reminder but since it's confusing other people just remove it and comment the missing-feature stuff instead. Signed-off-by: Ilpo Järvinen <redacted> Cc: Arnd Hannemann <redacted> --- net/ipv4/tcp_input.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 3f2f090..125b451 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c@@ -1178,10 +1178,18 @@ static void tcp_mark_lost_retrans(struct sock *sk) if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)) continue; - if (after(received_upto, ack_seq) && - (tcp_is_fack(tp) || - !before(received_upto, - ack_seq + tp->reordering * tp->mss_cache))) { + /* 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);
--
1.5.6.5