linux-kernel - Re: [PATCH 8/8] mfd: lm3533: Simplify function return logic

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Date:	Wed, 30 Sep 2015 17:55:13 -0400
From:	Johan Hovold <johan@...nel.org>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org,
	Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH 8/8] mfd: lm3533: Simplify function return logic

On Wed, Sep 30, 2015 at 11:41:26PM +0200, Javier Martinez Canillas wrote:
> On 09/30/2015 11:04 PM, Johan Hovold wrote:
> > On Tue, Sep 29, 2015 at 01:26:08PM +0200, Javier Martinez Canillas wrote:

> >> diff --git a/drivers/mfd/lm3533-core.c b/drivers/mfd/lm3533-core.c
> >> index 643f3750e830..193ecee1fa7e 100644
> >> --- a/drivers/mfd/lm3533-core.c
> >> +++ b/drivers/mfd/lm3533-core.c
> >> @@ -472,11 +472,7 @@ static int lm3533_device_setup(struct lm3533 *lm3533,
> >>  	if (ret)
> >>  		return ret;
> >>  
> >> -	ret = lm3533_set_boost_ovp(lm3533, pdata->boost_ovp);
> >> -	if (ret)
> >> -		return ret;
> >> -
> >> -	return 0;
> >> +	return lm3533_set_boost_ovp(lm3533, pdata->boost_ovp);
> > 
> > You're saving a few lines of code but instead introduce asymmetries and
> > obscure the fact that the function returns zero on success.
> 
> I don't think the change makes the code more obscure tbh, the return foo()
> construct is very common in the kernel and most functions return 0 on
> success and a negative errno code on failure.

But it was perfectly obvious from just looking at the function before
your change.
 
> Also, we have a coccinelle semantic patch to find this pattern [0] so if
> you think that is not worth it, please add a comment to the code. Otherwise
> another developer could attempt to post the same patch since make coccicheck
> will always complain about this file.

Yes, I've NAKed similar so called clean up patches based on that pattern
for USB-serial and would be very glad to see that semantic patch removed.

Coccinelle can be very useful to detect and fix real bugs, but this
return-value exercise is just pointless at best.

Johan
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