linux-kernel - Re: [PATCH] platform/x86: sony-laptop: Mark expected switch fall-through

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Date:   Sun, 8 Jul 2018 03:56:17 +0900
From:   Mattia Dongili <malattia@...ux.it>
To:     Darren Hart <dvhart@...radead.org>
Cc:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Andy Shevchenko <andy@...radead.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/x86: sony-laptop: Mark expected switch
 fall-through

On Fri, Jul 06, 2018 at 04:24:27PM -0700, Darren Hart wrote:
> On Thu, Jul 05, 2018 at 03:47:03PM -0500, Gustavo A. R. Silva wrote:
> > In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> > where we are expecting to fall through.
> > 
> > Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> > ---
> >  drivers/platform/x86/sony-laptop.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
> > index b205b03..e614cb7 100644
> > --- a/drivers/platform/x86/sony-laptop.c
> > +++ b/drivers/platform/x86/sony-laptop.c
> > @@ -4427,6 +4427,7 @@ sony_pic_read_possible_resource(struct acpi_resource *resource, void *context)
> >  	default:
> >  		dprintk("Resource %d isn't an IRQ nor an IO port\n",
> >  			resource->type);
> > +		/* fall through */
> 
> Here too, I wonder if this is intentional. Either way, from what I can see, the
> final line in the function:
> 
> 	return AE_CTRL_TERMINATE;
> 
> Is unreachable as there are no "break" statements in the switch, and the default
> falls through to return AE_OK. Something doesn't seem right here.

I think so too. Looks to me that the default case was meant to return
AE_CTRL_TERMINATE (i.e. swapping it to be last would do).

Having written that code aeons ago, I'm not sure if there is a good
reason to be like that, though it still looks like a bug (that
existed ever since...).

Want to fix it as part of this patch series? Or I can send a patch
myself, let me know.

-- 
mattia
:wq!