Re: [PATCH v4 1/5] media: Determine early whether an IOCTL is supported

Hans Verkuil
2016-08-22T12:53:50Z

On 08/11/2016 10:29 PM, Sakari Ailus wrote:
> Preparation for refactoring media IOCTL handling to unify common parts.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

> ---
> drivers/media/media-device.c | 54 ++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 52 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index 1795abe..aedd64e 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -419,13 +419,41 @@ static long media_device_get_topology(struct media_device *mdev,
> return 0;
> }
>
> -static long media_device_ioctl(struct file *filp, unsigned int cmd,
> - unsigned long arg)
> +#define MEDIA_IOC(__cmd) \
> + [_IOC_NR(MEDIA_IOC_##__cmd)] = { .cmd = MEDIA_IOC_##__cmd }
> +
> +/* the table is indexed by _IOC_NR(cmd) */
> +struct media_ioctl_info {
> + unsigned int cmd;
> +};
> +
> +static const struct media_ioctl_info ioctl_info[] = {
> + MEDIA_IOC(DEVICE_INFO),
> + MEDIA_IOC(ENUM_ENTITIES),
> + MEDIA_IOC(ENUM_LINKS),
> + MEDIA_IOC(SETUP_LINK),
> + MEDIA_IOC(G_TOPOLOGY),
> +};
> +
> +static inline long is_valid_ioctl(const struct media_ioctl_info *info,
> + unsigned int cmd)
> +{
> + return (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info)
> + || info[_IOC_NR(cmd)].cmd != cmd) ? -ENOIOCTLCMD : 0;
> +}
> +
> +static long __media_device_ioctl(
> + struct file *filp, unsigned int cmd, void __user *arg,
> + const struct media_ioctl_info *info_array)
> {
> struct media_devnode *devnode = media_devnode_data(filp);
> struct media_device *dev = devnode->media_dev;
> long ret;
>
> + ret = is_valid_ioctl(info_array, cmd);
> + if (ret)
> + return ret;
> +
> mutex_lock(&dev->graph_mutex);
> switch (cmd) {
> case MEDIA_IOC_DEVICE_INFO:
> @@ -461,6 +489,13 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
> return ret;
> }
>
> +static long media_device_ioctl(struct file *filp, unsigned int cmd,
> + unsigned long arg)
> +{
> + return __media_device_ioctl(
> + filp, cmd, (void __user *)arg, ioctl_info);
> +}
> +
> #ifdef CONFIG_COMPAT
>
> struct media_links_enum32 {
> @@ -491,6 +526,14 @@ static long media_device_enum_links32(struct media_device *mdev,
>
> #define MEDIA_IOC_ENUM_LINKS32 _IOWR('|', 0x02, struct media_links_enum32)
>
> +static const struct media_ioctl_info compat_ioctl_info[] = {
> + MEDIA_IOC(DEVICE_INFO),
> + MEDIA_IOC(ENUM_ENTITIES),
> + MEDIA_IOC(ENUM_LINKS32),
> + MEDIA_IOC(SETUP_LINK),
> + MEDIA_IOC(G_TOPOLOGY),
> +};
> +
> static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
> unsigned long arg)
> {
> @@ -498,6 +541,13 @@ static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
> struct media_device *dev = devnode->media_dev;
> long ret;
>
> + /*
> + * The number of supported IOCTLs is the same for both regular and
> + * compat cases. Instead of passing the sizes around, ensure that
> + * they match.
> + */
> + BUILD_BUG_ON(ARRAY_SIZE(ioctl_info) != ARRAY_SIZE(compat_ioctl_info));
> +
> switch (cmd) {
> case MEDIA_IOC_ENUM_LINKS32:
> mutex_lock(&dev->graph_mutex);
>