netdev - Re: [-next] Regression: ssh log in slowdown

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Date:	Thu, 12 Jun 2014 13:28:18 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Tom Herbert <therbert@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Cc:	Linux-Next <linux-next@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [-next] Regression: ssh log in slowdown

cc netdev@...r.kernel.org

On Thu, Jun 12, 2014 at 1:26 PM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> When logging in remotely using ssh, there's now a 10 second delay,
> cfr. the "ssh -v" output below:
>
> debug1: ssh_ecdsa_verify: signature correct
> debug1: SSH2_MSG_NEWKEYS sent
> debug1: expecting SSH2_MSG_NEWKEYS
> debug1: SSH2_MSG_NEWKEYS received
> debug1: Roaming not allowed by server
> debug1: SSH2_MSG_SERVICE_REQUEST sent
> debug1: SSH2_MSG_SERVICE_ACCEPT received
>
> ----- 10 s delay ---
>
> debug1: Authentications that can continue: publickey,password
> debug1: Next authentication method: publickey
>
> Wireshark doesn't show anything suspicious, just that there's a 10 s gap
> before I receive an "encrypted response packet" on the client.
>
> Hardware is r8a7791/koelsch, using sh_eth.
>
> I bisected this to
> commit 7e3cead5172927732f51fde77fef6f521e22f209
> Author: Tom Herbert <therbert@...gle.com>
> Date:   Tue Jun 10 18:54:19 2014 -0700
>
>     net: Save software checksum complete
>
>     In skb_checksum complete, if we need to compute the checksum for the
>     packet (via skb_checksum) save the result as CHECKSUM_COMPLETE.
>     Subsequent checksum verification can use this.
>
>     Also, added csum_complete_sw flag to distinguish between software and
>     hardware generated checksum complete, we should always be able to trust
>     the software computation.
>
>     Signed-off-by: Tom Herbert <therbert@...gle.com>
>     Signed-off-by: David S. Miller <davem@...emloft.net>
>
> Reverting this commit fixes the issue.
>
> Anyone with a clue?
>
> Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvald
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