[PATCH 2/2] drm: set dev_mapping before calling drm_open_helper

[Thomas Hellstrom]

Reviewed-by: Thomas Hellstrom <thellstrom at vmware.com>

On 10/29/2012 06:35 PM, Ilija Hadzic wrote:
> Some drivers (specifically vmwgfx) look at dev_mapping
> in their open hook, so we have to set dev->dev_mapping
> earlier in the process.
>
> Reference:
> http://lists.freedesktop.org/archives/dri-devel/2012-October/029420.html
>
> Signed-off-by: Ilija Hadzic <ihadzic at research.bell-labs.com>
> Reported-by: Thomas Hellstrom <thellstrom at vmware.com>
> Cc: stable at vger.kernel.org
> ---
>   drivers/gpu/drm/drm_fops.c | 47 +++++++++++++++++++++++++++++-----------------
>   1 file changed, 30 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
> index af68eca..133b413 100644
> --- a/drivers/gpu/drm/drm_fops.c
> +++ b/drivers/gpu/drm/drm_fops.c
> @@ -121,6 +121,8 @@ int drm_open(struct inode *inode, struct file *filp)
>   	int minor_id = iminor(inode);
>   	struct drm_minor *minor;
>   	int retcode = 0;
> +	int need_setup = 0;
> +	struct address_space *old_mapping;
>   
>   	minor = idr_find(&drm_minors_idr, minor_id);
>   	if (!minor)
> @@ -132,26 +134,37 @@ int drm_open(struct inode *inode, struct file *filp)
>   	if (drm_device_is_unplugged(dev))
>   		return -ENODEV;
>   
> +	if (!dev->open_count++)
> +		need_setup = 1;
> +	mutex_lock(&dev->struct_mutex);
> +	old_mapping = dev->dev_mapping;
> +	if (old_mapping == NULL)
> +		dev->dev_mapping = &inode->i_data;
> +	/* ihold ensures nobody can remove inode with our i_data */
> +	ihold(container_of(dev->dev_mapping, struct inode, i_data));
> +	inode->i_mapping = dev->dev_mapping;
> +	filp->f_mapping = dev->dev_mapping;
> +	mutex_unlock(&dev->struct_mutex);
> +
>   	retcode = drm_open_helper(inode, filp, dev);
> -	if (!retcode) {
> -		atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
> -		if (!dev->open_count++) {
> -			retcode = drm_setup(dev);
> -			if (retcode)
> -				dev->open_count--;
> -		}
> -	}
> -	if (!retcode) {
> -		mutex_lock(&dev->struct_mutex);
> -		if (dev->dev_mapping == NULL)
> -			dev->dev_mapping = &inode->i_data;
> -		/* ihold ensures nobody can remove inode with our i_data */
> -		ihold(container_of(dev->dev_mapping, struct inode, i_data));
> -		inode->i_mapping = dev->dev_mapping;
> -		filp->f_mapping = dev->dev_mapping;
> -		mutex_unlock(&dev->struct_mutex);
> +	if (retcode)
> +		goto err_undo;
> +	atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
> +	if (need_setup) {
> +		retcode = drm_setup(dev);
> +		if (retcode)
> +			goto err_undo;
>   	}
> +	return 0;
>   
> +err_undo:
> +	mutex_lock(&dev->struct_mutex);
> +	filp->f_mapping = old_mapping;
> +	inode->i_mapping = old_mapping;
> +	iput(container_of(dev->dev_mapping, struct inode, i_data));
> +	dev->dev_mapping = old_mapping;
> +	mutex_unlock(&dev->struct_mutex);
> +	dev->open_count--;
>   	return retcode;
>   }
>   EXPORT_SYMBOL(drm_open);