linux-kernel - Re: [RFC][PATCH 2/2] ACPI video: Don't start video device until its associated input device has been reigstered

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Date:	Tue, 28 Feb 2012 17:17:21 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Igor Murzov <intergalactic.anonymous@...il.com>
Cc:	Zhang Rui <rui.zhang@...el.com>, Len Brown <lenb@...nel.org>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Igor Murzov <e-mail@...e.by>,
	"Sergey V." <sftp.mtuci@...il.com>
Subject: Re: [RFC][PATCH 2/2] ACPI video: Don't start video device until its
 associated input device has been reigstered

On Tue, Feb 28, 2012 at 04:39:15PM -0800, Dmitry Torokhov wrote:
> On Wed, Feb 29, 2012 at 03:55:18AM +0400, Igor Murzov wrote:
> > From 202f25d44b1cf871697c88a6a3a8d854674db4d8 Mon Sep 17 00:00:00 2001
> > From: Igor Murzov <e-mail@...e.by>
> > Date: Mon, 27 Feb 2012 21:57:59 +0400
> > Subject: [PATCH 2/2] ACPI video: Don't start video device until its
> >  associated input device has been reigstered
> 
> > 
> > ---
> >  drivers/acpi/video.c |   10 ++++++----
> >  1 files changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> > index 1bc6370..b9e114c 100644
> > --- a/drivers/acpi/video.c
> > +++ b/drivers/acpi/video.c
> > @@ -1659,9 +1659,6 @@ static int acpi_video_bus_add(struct acpi_device *device)
> >  	error = acpi_video_bus_get_devices(video, device);
> >  	if (error)
> >  		goto err_free_video;
> > -	error = acpi_video_bus_start_devices(video);
> > -	if (error)
> > -		goto err_put_video;
> >  
> >  	video->input = input = input_allocate_device();
> >  	if (!input) {
> > @@ -1703,13 +1700,18 @@ static int acpi_video_bus_add(struct acpi_device *device)
> >  	if (error)
> >  		goto err_free_input_dev;
> >  
> > +	error = acpi_video_bus_start_devices(video);
> > +	if (error)
> > +		goto err_unregister_pm_notifier;
> > +
> 
> Registered input device should be unregistered with
> input_unregister_device(), not input_free_device(). Your change breaks
> this.
> 
> Also, notify() will not be called until acpi_video_bus_add() completes
> so current code should be perfectly fine.

Hm, I take the last paragraph back - in addition to bus notifier we do
install device notifier explicitly so it might fire up early. The
easiest fox would be to move acpi_video_bus_start_devices after
input_allocate_device() but before input_refister_device() -
unregistered input devoces can handle input_event() calls just fine.

-- 
Dmitry
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