linux-kernel - Re: [PATCH 1/3] iio: dummy: convert all simple allocation devm

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Date:   Sat, 5 Dec 2020 16:36:18 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] iio: dummy: convert all simple allocation devm_
 variants

On Thu, 3 Dec 2020 11:50:03 +0200
Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:

> Since a main requirement for an IIO device is to have a parent device
> object, it makes sense to attach more of the IIO device's objects to the
> lifetime of the parent object, to clean up the code.
> The idea is to also provide a base example that is more up-to-date with
> what's going on lately with most IIO drivers.

To some degree maybe, it's also very very handy for testing odd corner
cases with.  I'd definitely not recommend it as a reference driver
because it inherently has some odd corners because we need to
fake various things that don't exist without hardware.

> 
> This change tackles the simple allocations, to convert them to
> device-managed calls, and tie them to the parent device.

I'm confused or maybe I missrecall how this works.

IIRC there isn't a parent device...

Maybe we could create one via a bit of smoke and magic.


> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> ---
>  drivers/iio/dummy/iio_simple_dummy.c | 29 ++++++++--------------------
>  1 file changed, 8 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iio/dummy/iio_simple_dummy.c b/drivers/iio/dummy/iio_simple_dummy.c
> index c0b7ef900735..2a2e62f780a1 100644
> --- a/drivers/iio/dummy/iio_simple_dummy.c
> +++ b/drivers/iio/dummy/iio_simple_dummy.c
> @@ -574,11 +574,9 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
>  	 * parent = &client->dev;
>  	 */
>  
> -	swd = kzalloc(sizeof(*swd), GFP_KERNEL);
> -	if (!swd) {
> -		ret = -ENOMEM;
> -		goto error_kzalloc;
> -	}
> +	swd = devm_kzalloc(parent, sizeof(*swd), GFP_KERNEL);
> +	if (!swd)
> +		return ERR_PTR(-ENOMEM);
>  	/*
>  	 * Allocate an IIO device.
>  	 *
> @@ -587,11 +585,9 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
>  	 * It also has a region (accessed by iio_priv()
>  	 * for chip specific state information.
>  	 */
> -	indio_dev = iio_device_alloc(parent, sizeof(*st));
> -	if (!indio_dev) {
> -		ret = -ENOMEM;
> -		goto error_ret;
> -	}
> +	indio_dev = devm_iio_device_alloc(parent, sizeof(*st));
> +	if (!indio_dev)
> +		return ERR_PTR(-ENOMEM);
>  
>  	st = iio_priv(indio_dev);
>  	mutex_init(&st->lock);
> @@ -615,7 +611,7 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
>  	 *    indio_dev->name = id->name;
>  	 *    indio_dev->name = spi_get_device_id(spi)->name;
>  	 */
> -	indio_dev->name = kstrdup(name, GFP_KERNEL);
> +	indio_dev->name = devm_kstrdup(parent, name, GFP_KERNEL);
>  
>  	/* Provide description of available channels */
>  	indio_dev->channels = iio_dummy_channels;
> @@ -632,7 +628,7 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
>  
>  	ret = iio_simple_dummy_events_register(indio_dev);
>  	if (ret < 0)
> -		goto error_free_device;
> +		return ERR_PTR(ret);
>  
>  	ret = iio_simple_dummy_configure_buffer(indio_dev);
>  	if (ret < 0)
> @@ -649,11 +645,6 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
>  	iio_simple_dummy_unconfigure_buffer(indio_dev);
>  error_unregister_events:
>  	iio_simple_dummy_events_unregister(indio_dev);
> -error_free_device:
> -	iio_device_free(indio_dev);
> -error_ret:
> -	kfree(swd);
> -error_kzalloc:
>  	return ERR_PTR(ret);
>  }
>  
> @@ -683,10 +674,6 @@ static int iio_dummy_remove(struct iio_sw_device *swd)
>  
>  	iio_simple_dummy_events_unregister(indio_dev);
>  
> -	/* Free all structures */
> -	kfree(indio_dev->name);
> -	iio_device_free(indio_dev);
> -
>  	return 0;
>  }
>