linux-kernel - Re: [PATCH 4/4] extcon: arizona: Eliminate dead error handling code

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Message-ID: <20131112143031.GF6549@opensource.wolfsonmicro.com>
Date:	Tue, 12 Nov 2013 14:30:31 +0000
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
Cc:	myungjoo.ham@...sung.com, sameo@...ux.intel.com,
	lee.jones@...aro.org, patches@...nsource.wolfsonmicro.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] extcon: arizona: Eliminate dead error handling code

On Tue, Nov 12, 2013 at 09:15:29AM +0900, Chanwoo Choi wrote:
> Hi CHarles,
> 
> On 11/08/2013 10:19 PM, Charles Keepax wrote:
> > As a small disclaimer I would personally prefer to not merge this patch.
> > I have added it based on previous code review of the other patches in
> > this chain.
> > 
> > arizona_hpdet_do_id currently can only return 0 or -EAGAIN making the
> > else if clause handling error codes redundant, this patch removes this
> > clause.
> > 
> > Whilst this clause is not currently hit removing it makes the code
> > fragile. It will not be obvious whilst editing arizona_hpdet_do_id that
> > you shouldn't add a return value other than 0 or -EAGAIN.
> > 
> > Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> > ---
> >  drivers/extcon/extcon-arizona.c |    5 +++--
> >  1 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/extcon/extcon-arizona.c b/drivers/extcon/extcon-arizona.c
> > index 0d70bf6..2313b1e 100644
> > --- a/drivers/extcon/extcon-arizona.c
> > +++ b/drivers/extcon/extcon-arizona.c
> > @@ -476,6 +476,9 @@ static int arizona_hpdet_read(struct arizona_extcon_info *info)
> >  	return val;
> >  }
> >  
> > +/* This function should only return 0 or -EAGAIN, if other return values are
> > + * added additional handling should be added in arizona_hpdet_irq.
> > + */
> 
> As Lee Jones commented, you should modify this comment of arizona_hpdet_do_id() and add
> the description of return value. Because arizoa_hpdet_do_id() has different meaning
> between -EAGAIN and other minus value.

I take it you are still very keen on applying a patch for this
dead code elimination? I really do feel it would be better to
leave this part of the code as it currently is, the extra safety
clearly outweights the cost of a redundant else if.

Thanks,
Charles
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