Re: [PATCH -next] I2C: Use helper function IS_ERR_OR_NULL()

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Ruan Jinjie <ruanjinjie@huawei.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Andi Shyti <andi.shyti@kernel.org>,
	Fabio Estevam <festevam@gmail.com>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Claudiu Beznea <claudiu.beznea@tuxon.dev>,
	linux-i2c@vger.kernel.org,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Codrin Ciubotariu <codrin.ciubotariu@microchip.com>,
	Oleksij Rempel <linux@rempel-privat.de>,
	Shawn Guo <shawnguo@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [PATCH -next] I2C: Use helper function IS_ERR_OR_NULL()
Date: Wed, 16 Aug 2023 11:08:03 +0100	[thread overview]
Message-ID: <ZNygA72nKogZvlG3@shell.armlinux.org.uk> (raw)
In-Reply-To: <50f61322-de65-1632-d404-7dcfe9a82744@huawei.com>

On Wed, Aug 16, 2023 at 05:48:34PM +0800, Ruan Jinjie wrote:
> 
> 
> On 2023/8/16 17:46, Ruan Jinjie wrote:
> > Use IS_ERR_OR_NULL() instead of open-coding it
> > to simplify the code.
> > 
> > Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
> > ---
> >  drivers/i2c/busses/i2c-at91-master.c | 2 +-
> >  drivers/i2c/busses/i2c-imx.c         | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
> > index 94cff1cd527e..0e454c04a145 100644
> > --- a/drivers/i2c/busses/i2c-at91-master.c
> > +++ b/drivers/i2c/busses/i2c-at91-master.c
> > @@ -831,7 +831,7 @@ static int at91_init_twi_recovery_gpio(struct platform_device *pdev,
> >  	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
> >  
> >  	rinfo->pinctrl = devm_pinctrl_get(&pdev->dev);
> > -	if (!rinfo->pinctrl || IS_ERR(rinfo->pinctrl)) {
> > +	if (IS_ERR_OR_NULL(rinfo->pinctrl)) {
> >  		dev_info(dev->dev, "can't get pinctrl, bus recovery not supported\n");
> >  		return PTR_ERR(rinfo->pinctrl);
> >  	}
> > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> > index 10e89586ca72..8807c90df749 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -1388,7 +1388,7 @@ static int i2c_imx_init_recovery_info(struct imx_i2c_struct *i2c_imx,
> >  	struct i2c_bus_recovery_info *rinfo = &i2c_imx->rinfo;
> >  
> >  	i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
> > -	if (!i2c_imx->pinctrl || IS_ERR(i2c_imx->pinctrl)) {
> > +	if (!IS_ERR_OR_NULL(i2c_imx->pinctrl)) {
> 
> Sorry, there is a problem, please ignore it.

I don't think these conversions are appropriate for devm_pinctrl_get().
If one reads the code for devm_pinctrl_get() and pinctrl_get(), then
one finds that it will never return NULL.

So the tests for NULL do not serve any practical purpose than giving
coders a warm fuzzy feeling that they've tested for a NULL pointer.
Practically, they are of no use, so should be removed... thus making
the conversion to IS_ERR_OR_NULL() irrelevant.

-- 
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