netdev - Re: Memory corruption with r8169 across several device revisions and kernels

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Message-Id: <20180123.203316.1537241370565274071.davem@davemloft.net>
Date:   Tue, 23 Jan 2018 20:33:16 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     o.freyermuth@...glemail.com
Cc:     romieu@...zoreil.com, netdev@...r.kernel.org
Subject: Re: Memory corruption with r8169 across several device revisions
 and kernels

From: Oliver Freyermuth <o.freyermuth@...glemail.com>
Date: Wed, 24 Jan 2018 02:21:55 +0100

> Am 23.01.2018 um 23:13 schrieb Francois Romieu:
>> 
>> It helps. Can you try the snippet below ?
> 
> It seems to fix the issue - I could not reproduce memory corruption
> anymore neither on an Ubuntu 17.10.1 live system (with patched
> kernel module) nor on my Gentoo system (4.14.12 with your patch
> applied) across several reboots and module reloads!

Thanks for helping test this out.

> Sorry for my ignorance, but I'm curious - the R32 is there to avoid
> reordering of the writes?

The R32 make sure the write(s) beforehand have reached the chip, and
indeed another thing it ensures is write ordering.

> Many thanks for the quick help. I don't know the policies, but from
> user point of view, this should be a good candidate for backporting
> to stable kernels, since many systems in the wild should be affected
> by this, and spurious memory corruption leading to e.g. broken
> filesystems is rather nasty.

Hopefully Francois can post a bonafide patch for me to apply with
a full commit log message etc.

I'm really surprised we were clearing those registers after
programming properly, I wonder what that was all about. :-/

Thanks again for your testing and help.