linux-kernel - Re: [PATCH 3/3] EDAC: amd64_edac: decide if driver can load successfully early.

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Date:	Thu, 19 Mar 2015 12:33:30 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Doug Thompson <dougthompson@...ssion.com>,
	linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Olof Johansson <olof@...om.net>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Luis R . Rodriguez" <mcgrof@...e.com>
Subject: Re: [PATCH 3/3] EDAC: amd64_edac: decide if driver can load
 successfully early.

Hello, Borislav.

On Thu, Mar 19, 2015 at 05:23:02PM +0100, Borislav Petkov wrote:
> On Thu, Mar 19, 2015 at 09:12:26AM -0700, Dmitry Torokhov wrote:
> > By the same token it only makes sense to load e1000e when I have e1000e
> > device loaded, but we allow it to load anyway. Or psmouse. Or pretty
> > much any other drivers (sans some platform code). The fact is that we
> > for long time have separated module loading and driver binding. Loading
> > driver even without the devices is standard behavior.
> 
> FWIW, I always hated that.

You understand that there are technical reasons behind the current
behavior?  This is not something people just did on a whim.  We used
to have autounload and all that but over time moved away from it
because the trade-offs around the behavior shifted.

I don't get why you don't understand this.  As a general rule, we
don't go and implement one-off behaviors like this because it's well
understood that things like this are more costly in the longer term.
As said multiple times before, if you think this is a class of problem
worth solving, do so properly.  Please stop shell scripting in your
->probe() in kernel.

> If I detect at least one NB which is ok, I can then continue and do
> pci_register_driver(). If there are no suitable NBs, I return an error
> and don't even touch PCI.

Please don't.  Consider it nacked preemptively.  If you want to solve
this and can justify the added complexity, solve it in a general way -
teach it to the driver model.

Thanks.

-- 
tejun
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