linux-kernel - Re: [PATCH v2] staging: iio: ad7816: Switch to the gpio descriptor interface

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Date:   Wed, 17 Oct 2018 22:56:32 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     Nishad Kamdar <nishadkamdar@...il.com>, devel@...verdev.osuosl.org,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        linux-iio@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, outreachy-kernel@...glegroups.com,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Hartmut Knaack <knaack.h@....de>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH v2] staging: iio: ad7816: Switch to the gpio descriptor
 interface

On Wed, Oct 17, 2018 at 10:58:23AM -0400, Sasha Levin wrote:
> On Wed, Oct 17, 2018 at 08:17:20PM +0530, Nishad Kamdar wrote:
> > +	chip->rdwr_pin = devm_gpiod_get(&spi_dev->dev, "rdwr", GPIOD_IN);
> > +	if (IS_ERR(chip->rdwr_pin)) {
> > +		ret = PTR_ERR(chip->rdwr_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request rdwr GPIO: %d\n",
> > +			ret);
> > 		return ret;
> > 	}
> > -	gpio_direction_input(chip->rdwr_pin);
> > -	ret = devm_gpio_request(&spi_dev->dev, chip->convert_pin,
> > -				spi_get_device_id(spi_dev)->name);
> > -	if (ret) {
> > -		dev_err(&spi_dev->dev, "Fail to request convert gpio PIN %d.\n",
> > -			chip->convert_pin);
> > +	chip->convert_pin = devm_gpiod_get(&spi_dev->dev, "convert", GPIOD_IN);
> > +	if (IS_ERR(chip->convert_pin)) {
> > +		ret = PTR_ERR(chip->convert_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request convert GPIO: %d\n",
> > +			ret);
> > 		return ret;
> > 	}
> > -	gpio_direction_input(chip->convert_pin);
> > -	ret = devm_gpio_request(&spi_dev->dev, chip->busy_pin,
> > -				spi_get_device_id(spi_dev)->name);
> > -	if (ret) {
> > -		dev_err(&spi_dev->dev, "Fail to request busy gpio PIN %d.\n",
> > -			chip->busy_pin);
> > +	chip->busy_pin = devm_gpiod_get(&spi_dev->dev, "busy", GPIOD_IN);
> > +	if (IS_ERR(chip->busy_pin)) {
> > +		ret = PTR_ERR(chip->busy_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request busy GPIO: %d\n",
> > +			ret);
> > 		return ret;
> > 	}
> 
> Hm, from what I can tell devm_gpio_request() is allocating some memory,
> which makes this a series of 4 allocations.
> 
> What happens if the fourth allocation fails? Do we leak the first three?

These are devm_ allocations.  They are freed when &spi_dev->dev is
released.

regards,
dan carpenter