Re: [PATCH 2/2] media: implement 32-on-64 bit compat IOCTL handling

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On Tue January 22 2013 17:27:56 Sakari Ailus wrote:
> Use the same handlers where the structs are the same. Implement a new
> handler for link enumeration since struct media_links_enum is different on
> 32-bit and 64-bit systems.

I think I would prefer to have the compat handling split off into a
seperate source. I know it is just a small amount of code at the moment,
but that's the way it is done as well for the V4L2 ioctls and I rather
like that approach.

What do others think about that?

Regards,

	Hans

> 
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxx>
> Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Tested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>  drivers/media/media-device.c |  102 ++++++++++++++++++++++++++++++++++++------
>  1 file changed, 89 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index d01fcb7..99b80b6 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -20,10 +20,11 @@
>   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
>   */
>  
> -#include <linux/types.h>
> +#include <linux/compat.h>
> +#include <linux/export.h>
>  #include <linux/ioctl.h>
>  #include <linux/media.h>
> -#include <linux/export.h>
> +#include <linux/types.h>
>  
>  #include <media/media-device.h>
>  #include <media/media-devnode.h>
> @@ -124,35 +125,31 @@ static void media_device_kpad_to_upad(const struct media_pad *kpad,
>  	upad->flags = kpad->flags;
>  }
>  
> -static long media_device_enum_links(struct media_device *mdev,
> -				    struct media_links_enum __user *ulinks)
> +static long __media_device_enum_links(struct media_device *mdev,
> +				      struct media_links_enum *links)
>  {
>  	struct media_entity *entity;
> -	struct media_links_enum links;
>  
> -	if (copy_from_user(&links, ulinks, sizeof(links)))
> -		return -EFAULT;
> -
> -	entity = find_entity(mdev, links.entity);
> +	entity = find_entity(mdev, links->entity);
>  	if (entity == NULL)
>  		return -EINVAL;
>  
> -	if (links.pads) {
> +	if (links->pads) {
>  		unsigned int p;
>  
>  		for (p = 0; p < entity->num_pads; p++) {
>  			struct media_pad_desc pad;
>  			media_device_kpad_to_upad(&entity->pads[p], &pad);
> -			if (copy_to_user(&links.pads[p], &pad, sizeof(pad)))
> +			if (copy_to_user(&links->pads[p], &pad, sizeof(pad)))
>  				return -EFAULT;
>  		}
>  	}
>  
> -	if (links.links) {
> +	if (links->links) {
>  		struct media_link_desc __user *ulink;
>  		unsigned int l;
>  
> -		for (l = 0, ulink = links.links; l < entity->num_links; l++) {
> +		for (l = 0, ulink = links->links; l < entity->num_links; l++) {
>  			struct media_link_desc link;
>  
>  			/* Ignore backlinks. */
> @@ -169,8 +166,26 @@ static long media_device_enum_links(struct media_device *mdev,
>  			ulink++;
>  		}
>  	}
> +
> +	return 0;
> +}
> +
> +static long media_device_enum_links(struct media_device *mdev,
> +				    struct media_links_enum __user *ulinks)
> +{
> +	struct media_links_enum links;
> +	int rval;
> +
> +	if (copy_from_user(&links, ulinks, sizeof(links)))
> +		return -EFAULT;
> +
> +	rval = __media_device_enum_links(mdev, &links);
> +	if (rval < 0)
> +		return rval;
> +
>  	if (copy_to_user(ulinks, &links, sizeof(*ulinks)))
>  		return -EFAULT;
> +
>  	return 0;
>  }
>  
> @@ -251,10 +266,71 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
>  	return ret;
>  }
>  
> +#ifdef CONFIG_COMPAT
> +
> +struct media_links_enum32 {
> +	__u32 entity;
> +	compat_uptr_t pads; /* struct media_pad_desc * */
> +	compat_uptr_t links; /* struct media_link_desc * */
> +	__u32 reserved[4];
> +};
> +
> +static long media_device_enum_links32(struct media_device *mdev,
> +				      struct media_links_enum32 __user *ulinks)
> +{
> +	struct media_links_enum links;
> +	compat_uptr_t pads_ptr, links_ptr;
> +
> +	memset(&links, 0, sizeof(links));
> +
> +	if (get_user(links.entity, &ulinks->entity)
> +	    || get_user(pads_ptr, &ulinks->pads)
> +	    || get_user(links_ptr, &ulinks->links))
> +		return -EFAULT;
> +
> +	links.pads = compat_ptr(pads_ptr);
> +	links.links = compat_ptr(links_ptr);
> +
> +	return __media_device_enum_links(mdev, &links);
> +}
> +
> +#define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)
> +
> +static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
> +				      unsigned long arg)
> +{
> +	struct media_devnode *devnode = media_devnode_data(filp);
> +	struct media_device *dev = to_media_device(devnode);
> +	long ret;
> +
> +	switch (cmd) {
> +	case MEDIA_IOC_DEVICE_INFO:
> +	case MEDIA_IOC_ENUM_ENTITIES:
> +	case MEDIA_IOC_SETUP_LINK:
> +		return media_device_ioctl(filp, cmd, arg);
> +
> +	case MEDIA_IOC_ENUM_LINKS32:
> +		mutex_lock(&dev->graph_mutex);
> +		ret = media_device_enum_links32(dev,
> +				(struct media_links_enum32 __user *)arg);
> +		mutex_unlock(&dev->graph_mutex);
> +		break;
> +
> +	default:
> +		ret = -ENOIOCTLCMD;
> +	}
> +
> +	return ret;
> +}
> +#endif /* CONFIG_COMPAT */
> +
>  static const struct media_file_operations media_device_fops = {
>  	.owner = THIS_MODULE,
>  	.open = media_device_open,
>  	.ioctl = media_device_ioctl,
> +#ifdef CONFIG_COMPAT
> +	.compat_ioctl = media_device_compat_ioctl,
> +#endif /* CONFIG_COMPAT */
>  	.release = media_device_close,
>  };
>  
> 
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