linux-kernel - RE: [PATCH 08/12] fsl/fman: Add Frame Manager support

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Message-ID: <DM2PR03MB383A5275392BBBD604FE71BE6B80@DM2PR03MB383.namprd03.prod.outlook.com>
Date:	Mon, 15 Jun 2015 14:23:14 +0000
From:	Liberman Igal <Igal.Liberman@...escale.com>
To:	Paul Bolle <pebolle@...cali.nl>,
	Madalin-Cristian Bucur <madalin.bucur@...escale.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	Scott Wood <scottwood@...escale.com>
Subject: RE: [PATCH 08/12] fsl/fman: Add Frame Manager support

Hi Paul,
Thank you very much for your feedback.

I'm planning to address the issues you've raised in the next submission.

Regards,
Igal Liberman.

> -----Original Message-----
> From: Paul Bolle [mailto:pebolle@...cali.nl]
> Sent: Thursday, June 11, 2015 12:38 PM
> To: Bucur Madalin-Cristian-B32716
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; linuxppc-
> dev@...ts.ozlabs.org; Wood Scott-B07421; Liberman Igal-B31950
> Subject: Re: [PATCH 08/12] fsl/fman: Add Frame Manager support
> 
> So I couldn't help having yet another look at the code, just to drive home my
> point.
> 
> On Thu, 2015-06-11 at 10:55 +0200, Paul Bolle wrote:
> > > +void *fm_drv_init(void)
> >
> > static.
> >
> > > +{
> > > +	memset(&fm_drvs, 0, sizeof(fm_drvs));
> 
> fm_drvs is an external variable. It is guaranteed to be zero, isn't it?
> 
> > > +	mutex_init(&fm_drv_mutex);
> > > +
> > > +	/* Register to the DTB for basic FM API */
> > > +	platform_driver_register(&fm_driver);
> > > +
> > > +	return &fm_drvs;
> 
> You're returning a pointer to external variable. How's that useful?
> 
> And note this is the last time we'll ever see fm_drvs. So I think that all this
> variable does for the code is getting initialized to zero, twice.
> 
> > > +}
> > > +
> > > +int fm_drv_free(void *p_fm_drv)
> >
> > static.
> >
> > > +{
> > > +	platform_driver_unregister(&fm_driver);
> > > +	mutex_destroy(&fm_drv_mutex);
> > > +
> > > +	return 0;
> 
> This function has one caller, which doesn't check the return value. So this
> should be a function returning void. Of course, a wrapper of two lines called
> only once means you should actually not put this into a separate function.
> 
> > > +}
> 
> > > +static void *p_fm_drv;
> >
> > > +static int __init __cold fm_load(void) {
> > > +	p_fm_drv = fm_drv_init();
> > > +	if (!p_fm_drv) {
> 
> fm_drv_init() returns a pointer to an external variable. So how can this
> happen?
> 
> > > +		pr_err("Failed to init FM wrapper!\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	pr_info("Freescale FM module\n");
> > > +	return 0;
> > > +}
> 
> This is all rather basic. It must be, otherwise I wouldn't spot it.
> 
> So I keep spotting these basic oddities, with every cup of coffee I treat
> myself to while reading through this, wherever I look. By now I'm sure
> there's no need for the netdev people to look at this, not yet.
> 
> 
> Paul Bolle