linux-kernel - Re: [RESEND PATCH V2] leds: sc27xx: Move mutex

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Message-ID: <20231012091602.GD8314@google.com>
Date:   Thu, 12 Oct 2023 10:16:02 +0100
From:   Lee Jones <lee@...nel.org>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc:     Chunyan Zhang <chunyan.zhang@...soc.com>,
        Pavel Machek <pavel@....cz>, linux-leds@...r.kernel.org,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH V2] leds: sc27xx: Move mutex_init() to the end of
 probe

On Thu, 12 Oct 2023, Baolin Wang wrote:

> 
> 
> On 10/12/2023 11:47 AM, Chunyan Zhang wrote:
> > Move the mutex_init() to avoid redundant mutex_destroy() calls after
> > that for each time the probe fails.
> > 
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
> > ---
> > Rebased onto linux-next.
> > 
> > V2:
> > - Move the mutex_init() to the end of .probe() instead of adding
> > mutex_destroy() according to Lee's comments.
> > ---
> >   drivers/leds/leds-sc27xx-bltc.c | 9 ++++-----
> >   1 file changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/leds/leds-sc27xx-bltc.c b/drivers/leds/leds-sc27xx-bltc.c
> > index af1f00a2f328..ef57e57ecf07 100644
> > --- a/drivers/leds/leds-sc27xx-bltc.c
> > +++ b/drivers/leds/leds-sc27xx-bltc.c
> > @@ -296,7 +296,6 @@ static int sc27xx_led_probe(struct platform_device *pdev)
> >   		return -ENOMEM;
> >   	platform_set_drvdata(pdev, priv);
> > -	mutex_init(&priv->lock);
> >   	priv->base = base;
> >   	priv->regmap = dev_get_regmap(dev->parent, NULL);
> >   	if (!priv->regmap) {
> > @@ -309,13 +308,11 @@ static int sc27xx_led_probe(struct platform_device *pdev)
> >   		err = of_property_read_u32(child, "reg", &reg);
> >   		if (err) {
> >   			of_node_put(child);
> > -			mutex_destroy(&priv->lock);
> >   			return err;
> >   		}
> >   		if (reg >= SC27XX_LEDS_MAX || priv->leds[reg].active) {
> >   			of_node_put(child);
> > -			mutex_destroy(&priv->lock);
> >   			return -EINVAL;
> >   		}
> > @@ -325,9 +322,11 @@ static int sc27xx_led_probe(struct platform_device *pdev)
> >   	err = sc27xx_led_register(dev, priv);
> >   	if (err)
> > -		mutex_destroy(&priv->lock);
> > +		return err;
> > -	return err;
> > +	mutex_init(&priv->lock);
> 
> I think it is better to prepare all the required resources before
> registering the led device, what I mean is moving mutex_init() before
> calling sc27xx_led_register().

Is the mutex used before this point?

If not, I don't see any reason to initialise it sooner.

-- 
Lee Jones [李琼斯]