netdev - Re: [PATCH v2] net: alx: use custom skb allocator

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Date:	Wed, 25 May 2016 19:53:41 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	feng.tang@...el.com
Cc:	edumazet@...gle.com, johannes@...solutions.net, jarod@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: alx: use custom skb allocator

From: Feng Tang <feng.tang@...el.com>
Date: Wed, 25 May 2016 14:49:54 +0800

> This patch follows Eric Dumazet's commit 7b70176421 for Atheros
> atl1c driver to fix one exactly same bug in alx driver, that the
> network link will be lost in 1-5 minutes after the device is up.
> 
> My laptop Lenovo Y580 with Atheros AR8161 ethernet device hit the
> same problem with kernel 4.4, and it will be cured by Jarod Wilson's
> commit c406700c for alx driver which get merged in 4.5. But there
> are still some alx devices can't function well even with Jarod's
> patch, while this patch could make them work fine. More details on
> 	https://bugzilla.kernel.org/show_bug.cgi?id=70761
> 
> The debug shows the issue is very likely to be related with the RX
> DMA address, specifically 0x...f80, if RX buffer get 0x...f80 several
> times, their will be RX overflow error and device will stop working.
> 
> For kernel 4.5.0 with Jarod's patch which works fine with my
> AR8161/Lennov Y580, if I made some change to the
> 	__netdev_alloc_skb
> 		--> __alloc_page_frag()
> to make the allocated buffer can get an address with 0x...f80,
> then the same error happens. If I make it to 0x...f40 or 0x....fc0,
> everything will be still fine. So I tend to believe that the
> 0x..f80 address cause the silicon to behave abnormally.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=70761
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Johannes Berg <johannes@...solutions.net>
> Cc: Jarod Wilson <jarod@...hat.com>
> Signed-off-by: Feng Tang <feng.tang@...el.com>
> Tested-by: Ole Lukoie <olelukoie@...l.ru>

Looks good, applied, thanks.

But now that we have at least two instances of this code we really
need to put a common version somewhere. :-/