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From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>,
	"barebox@lists.infradead.org" <barebox@lists.infradead.org>
Subject: Re: [PATCH 1/7] driver: introduce less error-prone dev_get_drvdata alternative
Date: Mon, 28 Sep 2020 17:46:02 +0200	[thread overview]
Message-ID: <42467587-1ae1-f501-add6-322b70193749@pengutronix.de> (raw)
In-Reply-To: <20200928154247.15619-1-a.fatoum@pengutronix.de>

On 9/28/20 5:42 PM, Ahmad Fatoum wrote:
> We use dev_get_drvdata to get the driver match data associated with a
> device. This has two shortcomings:
> 
>  - Linux has dev_get_drvdata too, which returns a private pointer for
>    driver specific info to associate with a device. We use dev->priv
>    (or more often container_of) for that in barebox instead
> 
>  - It nearly always involves a cast to a double pointer, which is
>    error-prone as size and alignment match need to be ensured
>    on the programmer's part and can easily be gotten wrong:
> 	enum dev_type type
> 	dev_get_drvdata(dev, (const void **)&type);
> 
> Add a new function that instead of using a double pointer argument,
> returns the pointer directly:
> 
>  - For normal pointer driver data, no cast is necessary
>  - For integer driver data casted to a pointer for storage,
>    the cast is still necessary, but

That ", but" should be removed. Sascha, could you fix this up
on apply (assuming there won't be a v2)?

> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/base/driver.c | 11 +++++++++++
>  include/driver.h      | 18 ++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index 412db6c40699..3205bbc3c33b 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -500,3 +500,14 @@ int dev_get_drvdata(struct device_d *dev, const void **data)
>  
>  	return -ENODEV;
>  }
> +
> +const void *device_get_match_data(struct device_d *dev)
> +{
> +	if (dev->of_id_entry)
> +		return dev->of_id_entry->data;
> +
> +	if (dev->id_entry)
> +		return (void *)dev->id_entry->driver_data;
> +
> +	return NULL;
> +}
> diff --git a/include/driver.h b/include/driver.h
> index 154525e0fde7..14220431f2d6 100644
> --- a/include/driver.h
> +++ b/include/driver.h
> @@ -534,8 +534,26 @@ int devfs_create_partitions(const char *devname,
>  #define DRV_OF_COMPAT(compat) \
>  	IS_ENABLED(CONFIG_OFDEVICE) ? (compat) : NULL
>  
> +/**
> + * dev_get_drvdata - get driver match data associated with device
> + * @dev: device instance
> + * @data: pointer to void *, where match data is stored
> + *
> + * Returns 0 on success and error code otherwise.
> + *
> + * DEPRECATED: use device_get_match_data instead, which avoids
> + * common pitfalls due to explicit pointer casts
> + */
>  int dev_get_drvdata(struct device_d *dev, const void **data);
>  
> +/**
> + * device_get_match_data - get driver match data associated with device
> + * @dev: device instance
> + *
> + * Returns match data on success and NULL otherwise
> + */
> +const void *device_get_match_data(struct device_d *dev);
> +
>  int device_match_of_modalias(struct device_d *dev, struct driver_d *drv);
>  
>  #endif /* DRIVER_H */
> 

-- 
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  parent reply	other threads:[~2020-09-28 15:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28 15:42 Ahmad Fatoum
2020-09-28 15:42 ` [PATCH 2/7] led: pca955x: fix probing from device tree Ahmad Fatoum
2020-09-29  7:19   ` Sascha Hauer
2020-09-30  7:28     ` Ahmad Fatoum
2020-09-28 15:42 ` [PATCH 3/7] dma: apbh: fix out-of-bounds write on 64-bit SoCs Ahmad Fatoum
2020-09-28 15:42 ` [PATCH 4/7] aiodev: lm75: " Ahmad Fatoum
2020-09-28 15:42 ` [PATCH 5/7] mtd: nand-mxs: " Ahmad Fatoum
2020-09-28 16:01   ` Marco Felsch
2020-09-28 16:03     ` Ahmad Fatoum
2020-09-28 16:08       ` Marco Felsch
2020-09-28 15:42 ` [PATCH 6/7] video: imx-hdmi: fix dev_get_drvdata misuse Ahmad Fatoum
2020-09-28 15:42 ` [PATCH 7/7] driver: migrate some from dev_get_drvdata to device_get_match_data Ahmad Fatoum
2020-09-28 15:46 ` Ahmad Fatoum [this message]
2020-09-29  6:45 ` [PATCH 1/7] driver: introduce less error-prone dev_get_drvdata alternative Sascha Hauer
2020-09-29  7:32 ` Sascha Hauer
2020-09-29  9:42   ` Ahmad Fatoum
2020-09-30  7:48     ` Sascha Hauer
2020-09-30 13:13       ` Ahmad Fatoum
2020-10-05  8:31         ` Ahmad Fatoum
2020-10-07  8:43           ` Sascha Hauer

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