linux-kernel - Re: [PATCH 6/12] drivers/platform/x86: Correct redundant test

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Date:	Tue, 28 Jul 2009 22:11:14 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Paulo Marques <pmarques@...popie.com>
Cc:	jwoithe@...sics.adelaide.edu.au, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 6/12] drivers/platform/x86: Correct redundant test

On Tue, 28 Jul 2009, Paulo Marques wrote:

> Julia Lawall wrote:
> > [...]
> > ---
> >  drivers/platform/x86/fujitsu-laptop.c          |    3 ---
> >  1 files changed, 0 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
> > index 218b9a1..5306901 100644
> > --- a/drivers/platform/x86/fujitsu-laptop.c
> > +++ b/drivers/platform/x86/fujitsu-laptop.c
> > @@ -745,9 +745,6 @@ static int acpi_fujitsu_remove(struct acpi_device *device, int type)
> >  
> >  	fujitsu = acpi_driver_data(device);
> >  
> > -	if (!device || !acpi_driver_data(device))
> > -		return -EINVAL;
> > -
> 
> Shouldn't this still do a:
> 
>    if (!fujitsu)
>      return -EINVAL;

acpi_driver_data just accesses a field of its argument.  Is there a worry 
that from one call to the next it could have a different value?

Perhaps it would be better to first test !device, then initialize fujitsu, 
and then test the result of fujitsu?  The acpi_driver_data, which might 
someday do something more complicated, would only be called once.

julia
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