Re: [PATCH] Fix sorting of SACK blocks

[David Miller <davem@davemloft.net>]

From: Baruch Even <baruch@ev-en.org>
Date: Thu, 25 Jan 2007 20:29:03 +0200

> The sorting of SACK blocks actually munges them rather than sort, causing the
> TCP stack to ignore some SACK information and breaking the assumption of
> ordered SACK blocks after sorting.
> 
> The sort takes the data from a second buffer which isn't moved causing
> subsequent data moves to occur from the wrong location. The fix is to
> use a temporary buffer as a normal sort does.
> 
> Signed-Off-By: Baruch Even <baruch@ev-en.org>

BTW, in reviewing this I note that there is now only one remaining
use of tp->recv_sack_cache[] and that is the code earlier in this
function which is trying to detect if all we are doing is extending
the leading edge of a SACK block.

It would be nice to be able to clear out that usage as well, and
remove recv_sack_cache[] and thus make tcp_sock smaller.