netdev - Re: mlx5e throwing RTNL_ASSERT error on vxlan_get_rx

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Date:	Mon, 25 Apr 2016 11:07:12 +0200
From:	Hannes Frederic Sowa <hannes@...hat.com>
To:	Saeed Mahameed <saeedm@....mellanox.co.il>,
	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Saeed Mahameed <saeedm@...lanox.com>,
	David Miller <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>,
	Matthew Finlay <matt@...lanox.com>,
	Yevgeny Petrilin <yevgenyp@...lanox.com>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: mlx5e throwing RTNL_ASSERT error on vxlan_get_rx_port

Hello,

On 22.04.2016 22:02, Saeed Mahameed wrote:
> On Fri, Apr 22, 2016 at 10:30 PM, Alexander Duyck
> <alexander.duyck@...il.com> wrote:
>> From what I can tell it looks like the recent commit that changed the
>> behavior for vxlan_get_rx_port has broken the mlx5 driver as it was
>> calling vxlan_get_rx_port in mlx5e_create_netdev which didn't hold the
>> rtnl lock.  As a result it is throwing RTNL_ASSERT errors.
>>
> 
> Nice catch Alex.
> 
>> I'm not sure if anyone has already seen this or not but I thought I
>> would bring it to your attention.  Odds are this probably something
>> that needs to be fixed in the mlx5e driver and if I have time I might
>> get to it sometime in the next several days if nobody else ends up
>> addressing it.
>>
> 
> Matt will handle it, he is already preparing two fixes in mlx5 vxlan
> area, one is to address the kconfig issue Arnd reported and the other
> is to address the scheduling while atomic in mlx5e_vxlan_add ndo
> implementation which can sleep, from vxlan module it is called under
> rcu_read_lock.

Hm, I probably overlooked something during review or this change in
vxlan_get_rx_port or something came in during the time I was pushing
those changes at the same time. I just had a look and the fix shouldn't
be that hard.

Thanks,
Hannes