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tcp: remove pointless .dsack/.num_sacks code 

In the pure assignment case, the earlier zeroing is
still in effect.

David S. Miller raised concerns if the ifs are there to avoid
dirtying cachelines. I came to these conclusions:

> We'll be dirty it anyway (now that I check), the first "real" statement
> in tcp_rcv_established is:
>
>       tp->rx_opt.saw_tstamp = 0;
>
> ...that'll land on the same dword. :-/
>
> I suppose the blocks are there just because they had more complexity
> inside when they had to calculate the eff_sacks too (maybe it would
> have been better to just remove them in that drop-patch so you would
> have had less head-ache :-)).

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 2009-03-14 14:23:01 +00:00 committed by David S. Miller
parent 7cd0a63872
commit 5861f8e58d
2 changed files with 3 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/ipv4/tcp_input.c
View File

@ -4248,8 +4248,7 @@ static void tcp_sack_remove(struct tcp_sock *tp)
this_sack++;
sp++;
}
if (num_sacks != tp->rx_opt.num_sacks)
tp->rx_opt.num_sacks = num_sacks;
tp->rx_opt.num_sacks = num_sacks;
}
/* This one checks to see if we can put data from the
@ -4325,8 +4324,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
TCP_ECN_accept_cwr(tp, skb);
if (tp->rx_opt.dsack)
tp->rx_opt.dsack = 0;
tp->rx_opt.dsack = 0;
/* Queue data for delivery to the user.
* Packets in sequence go to the receive queue.
@ -4445,7 +4443,6 @@ drop:
/* Initial out of order segment, build 1 SACK. */
if (tcp_is_sack(tp)) {
tp->rx_opt.num_sacks = 1;
tp->rx_opt.dsack = 0;
tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
tp->selective_acks[0].end_seq =
TCP_SKB_CB(skb)->end_seq;

3
net/ipv4/tcp_output.c
View File

@ -441,8 +441,7 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
*ptr++ = htonl(sp[this_sack].end_seq);
}
if (tp->rx_opt.dsack)
tp->rx_opt.dsack = 0;
tp->rx_opt.dsack = 0;
}
}