linux-kernel - Re: [PATCH] fujitsu-laptop: driver [un]registration fixes

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Date:	Tue, 22 Dec 2009 09:02:40 +1030 (CST)
From:	Jonathan Woithe <jwoithe@...sics.adelaide.edu.au>
To:	dmitry.torokhov@...il.com (Dmitry Torokhov)
Cc:	bzolnier@...il.com (Bartlomiej Zolnierkiewicz),
	jwoithe@...sics.adelaide.edu.au (Jonathan Woithe),
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fujitsu-laptop: driver [un]registration fixes

Hi Dmitry

> On Wed, Jul 29, 2009 at 10:15:33PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > @@ -722,22 +722,22 @@ static int acpi_fujitsu_add(struct acpi_
> >  
> >  	return result;
> >  
> > -end:
> > +err_unregister_input_dev:
> > +	input_unregister_device(input);
> >  err_free_input_dev:
> >  	input_free_device(input);
> >  err_stop:
> 
> Just noticed it scanning ACPI list. You must not use input_free_device()
> after calling input_unregister_device() since unregister likely drops the
> last reference to the device and it will get freed by input core.

So what's the correct way to deal with that in this case?  Something like

-end:
+err_unregister_input_dev:
+	input_unregister_device(input);
+	goto err_stop;
 err_free_input_dev:
 	input_free_device(input);
 err_stop:

(with a short comment to explain the goto) would circumvent the problem but
it looks ugly (at least to my eyes - I've never really liked "goto"s :-) ).

> For polled input devices you need to use both unregister and free though
> because polled device structure is not refcounted (but underlying input
> device is).

This isn't a polled input device AFAIK so this doesn't apply here, right?

Regards
  jonathan
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