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

cc netdev@vger.kernel.org

On Thu, Jun 12, 2014 at 1:26 PM, Geert Uytterhoeven
[off-list ref] 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 [off-list ref]
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 [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]

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@linux-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