netdev - Re: [PATCH] bridge: Module use count must be updated as bridges are created/destroyed

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Date:	Fri, 29 Apr 2011 17:07:01 +0100
From:	"Jan Beulich" <JBeulich@...ell.com>
To:	"Jon Masters" <jonathan@...masters.org>
Cc:	"David Miller" <davem@...emloft.net>,
	"Jon Masters" <jcm@...masters.org>,
	<shemminger@...ux-foundation.org>,
	<bridge@...ts.linux-foundation.org>, <jeffm@...e.com>,
	"Michal Marek" <mmarek@...e.cz>, <netdev@...r.kernel.org>
Subject: Re: [PATCH] bridge: Module use count must be updated as	
	 bridges are created/destroyed

>>> On 29.04.11 at 18:05, Jon Masters <jonathan@...masters.org> wrote:
> On Fri, 2011-04-29 at 13:08 +0200, Michal Marek wrote:
>> On 29.4.2011 11:09, Jan Beulich wrote:
>> >>>> On 29.04.11 at 10:44, David Miller<davem@...emloft.net>  wrote:
> 
>> >> Nothing on the system should be hitting modules with unload requests
>> >> unless the user explicitly asked for that specific module to be
>> >> unloaded.  At least not by default.
>> >>
>> >> So the me the problem is perhaps that "modprobe -r" does this auto
>> >> dependency unloading thing by default.
>> >>
>> >> When we first fixed network device drivers so that they now properly
>> >> always run with no module refcount at all, people complained because
>> >> there were some distributions that ran some daemon that periodically
>> >> looked for "unreferenced" modules and "helped" the user by
>> >> automatically unloaded them.
>> >>
>> >> We killed that foolish daemon, and we can fix "modprobe -r" too.
>> >
>> > Michal - aren't you the modutils maintainer?
>> 
>> That would be Jon (CC added).
> 
> Thanks. So the specific feature you mention was added precisely because
> some folks wanted to clean up ununsed modules by removing all of their
> dependencies. Since I've not been on this thread until now, can you let
> me know what precisely you need, and why? We can make the unloading of
> unused modules configurable, but it sounds like you're saying even that
> isn't good enough. What actually happens, what's the bug experience?

The problem observed was that unloading (via modprobe -r)
ebtable_broute.ko, bridge.ko was also unloaded, causing all
bridged networking to stop functioning on a machine.

Jan

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