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

From: Geert Uytterhoeven
Date: Fri Jun 13 2014 - 03:27:26 EST


Hi Tom,

cc lkml, as this is now in mainline

On Fri, Jun 13, 2014 at 2:59 AM, Tom Herbert <therbert@xxxxxxxxxx> wrote:
>> 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@xxxxxxxxxx>
>> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>>
>> Reverting this commit fixes the issue.
>>
>> Anyone with a clue?
>>
> Hi Geert,
>
> I'm very sorry that I seemed to have missed your initial bug report,
> thanks for bisecting the problem. I have posted a fix for this, please
> verify it if you can

Thanks for your patches!

I assume this is the series "[PATCH 0/4] Checksum fixes"
(marc.info/?l=linux-netdev&m=140261417832399&w=2)?

As I'm not subscribed to netdev, I cannot reply to that thread.

"[PATCH 1/4] net: Fix save software checksum complete" fixes the issue
for me.
However, "[PATCH 2/4] udp: call __skb_checksum_complete when doing full
checksum" reintroduces the exact same bad behavior :-(

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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 Torvalds
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