Re: [PATCH] cpufreq: brcmstb-avs-cpufreq: Fix some resource leaks in the error handling path of the probe function

[Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>]

Le 22/12/2020 à 05:35, Viresh Kumar a écrit :
> On 19-12-20, 11:17, Christophe JAILLET wrote:
> > If 'cpufreq_register_driver()' fails, we must release the resources
> > allocated in 'brcm_avs_prepare_init()' as already done in the remove
> > function.
> >
> > To do that, introduce a new function 'brcm_avs_prepare_uninit()' in order
> > to avoid code duplication. This also makes the code more readable (IMHO).
> >
> > Fixes: de322e085995 ("cpufreq: brcmstb-avs-cpufreq: AVS CPUfreq driver for Broadcom STB SoCs")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > I'm not sure that the existing error handling in the remove function is
> > correct and/or needed.
> > ---
> >   drivers/cpufreq/brcmstb-avs-cpufreq.c | 25 ++++++++++++++++++++-----
> >   1 file changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/cpufreq/brcmstb-avs-cpufreq.c b/drivers/cpufreq/brcmstb-avs-cpufreq.c
> > index 3e31e5d28b79..750ca7cfccb0 100644
> > --- a/drivers/cpufreq/brcmstb-avs-cpufreq.c
> > +++ b/drivers/cpufreq/brcmstb-avs-cpufreq.c
> > @@ -597,6 +597,16 @@ static int brcm_avs_prepare_init(struct platform_device *pdev)
> >   	return ret;
> >   }
> >   
> > +static void brcm_avs_prepare_uninit(struct platform_device *pdev)
> > +{
> > +	struct private_data *priv;
> > +
> > +	priv = platform_get_drvdata(pdev);
> > +
> > +	iounmap(priv->avs_intr_base);
> > +	iounmap(priv->base);
> > +}
> > +
> >   static int brcm_avs_cpufreq_init(struct cpufreq_policy *policy)
> >   {
> >   	struct cpufreq_frequency_table *freq_table;
> > @@ -732,21 +742,26 @@ static int brcm_avs_cpufreq_probe(struct platform_device *pdev)
> >   
> >   	brcm_avs_driver.driver_data = pdev;
> >   
> > -	return cpufreq_register_driver(&brcm_avs_driver);
> > +	ret = cpufreq_register_driver(&brcm_avs_driver);
> > +	if (ret)
> > +		goto err_uninit;
> > +
> > +	return 0;
> > +
> > +err_uninit:
> > +	brcm_avs_prepare_uninit(pdev);
> > +	return ret;
>
> Maybe rewrite as:
>
> 	ret = cpufreq_register_driver(&brcm_avs_driver);
> 	if (ret)
>                  brcm_avs_prepare_uninit(pdev);
> 	return ret;

Personlaly, I prefer what I have proposed. Having a clear and dedicated 
error handling path is more future proff, IMHO.

> >   }
> >   
> >   static int brcm_avs_cpufreq_remove(struct platform_device *pdev)
> >   {
> > -	struct private_data *priv;
> >   	int ret;
> >   
> >   	ret = cpufreq_unregister_driver(&brcm_avs_driver);
> >   	if (ret)
> >   		return ret;
>
> Instead of returning here, it can be just WARN_ON(ret); and then go on and free
> the resources and this needs to be done in a separate patch.

Ok, I agree (see my comment below the --- in my patch).
I'll send a patch for it when the first patch will be applied, unless 
you prefer if I resend as a serie.

CJ

> >   
> > -	priv = platform_get_drvdata(pdev);
> > -	iounmap(priv->base);
> > -	iounmap(priv->avs_intr_base);
> > +	brcm_avs_prepare_uninit(pdev);
> >   
> >   	return 0;
> >   }