Re: [PATCH net-next] eth: remove neterion/vxge

From: Jakub Kicinski <kuba@kernel.org>
To: Francois Romieu <romieu@fr.zoreil.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
	pabeni@redhat.com, corbet@lwn.net, jdmason@kudzu.us,
	vburru@marvell.com, jiawenwu@trustnetic.com,
	linux-doc@vger.kernel.org
Subject: Re: [PATCH net-next] eth: remove neterion/vxge
Date: Fri, 1 Jul 2022 14:40:10 -0700	[thread overview]
Message-ID: <20220701144010.5ae54364@kernel.org> (raw)
In-Reply-To: <Yr8rC9jXtoFbUIQ+@electric-eye.fr.zoreil.com>

On Fri, 1 Jul 2022 19:12:43 +0200 Francois Romieu wrote:
> Jakub Kicinski <kuba@kernel.org> :
> > The last meaningful change to this driver was made by Jon in 2011.
> > As much as we'd like to believe that this is because the code is
> > perfect the chances are nobody is using this hardware.  
> 
> It was used with some success in 2017:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=197881

Nice find! Quoting for the list:

  vxge.ko can work nicely for kernel version 4.1 (I tried 4.1.44)
  However, for any version beyond that (I tried 4.4, 4.8, 4.13)
  the card can be initiated - but when I tried to do some network
  transfer (for example, ssh) I saw something like.... 

  [Tx queue timeout stack trace follows]

I didn't see any fixes since 2017 so the problem must still be there.
Could be just a particular version of FW that's broken, tho.

> > Because of the size of this driver there is a nontrivial maintenance
> > cost to keeping this code around, in the last 2 years we're averaging
> > more than 1 change a month. Some of which require nontrivial review
> > effort, see commit 877fe9d49b74 ("Revert "drivers/net/ethernet/neterion/vxge:
> > Fix a use-after-free bug in vxge-main.c"") for example.  
> 
> vxge_remove() calls vxge_device_unregister().
> 
> vxge_device_unregister() does unregister_netdev() + ... + free_netdev().
> 
> vxge_remove() keeps using netdev_priv() pointer... :o/
> 
> Imho it is not nontrivial enough that top-level maintainers must handle it
> but it is just mvho that maintainers handle too much low-value stuff.

Ack, this particular bug is just an excuse, it can be fixed.

> Regarding the unused hardware side of the problem, it's a bit sad that
> there still is no centralized base of interested users for a given piece
> of hardware in 2022.

100%, I really wish something like that existed. I have a vague memory
of Fedora or some other distro collecting HW data. Maybe it died because
of privacy issues?

Knowing that stuff gets used would be a great motivation. Handling all
the academic / bot patches for stuff I think goes completely unused is
weighing down my psyche.