[PATCH] drm: Fix GETCONNECTOR regression

[Sean Paul]

On Tue, Jun 20, 2017 at 10:28:37PM +0200, Daniel Vetter wrote:
> In
> 
> commit 91eefc05f0ac71902906b2058360e61bd25137fe
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Wed Dec 14 00:08:10 2016 +0100
> 
>     drm: Tighten locking in drm_mode_getconnector
> 
> I reordered the logic a bit in that IOCTL, but that broke userspace
> since it'll get the new mode list, but not the new property values.
> Fix that again.
> 
> v2: Fix up the error path handling when copy_to_user for the modes
> failes (Dhinakaran).
> 
> Fixes: 91eefc05f0ac ("drm: Tighten locking in drm_mode_getconnector")
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: David Airlie <airlied at linux.ie>
> Cc: dri-devel at lists.freedesktop.org
> Reported-by: "H.J. Lu" <hjl.tools at gmail.com>
> Tested-by: "H.J. Lu" <hjl.tools at gmail.com>
> Cc: <stable at vger.kernel.org> # v4.11+
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100576
> Cc: "H.J. Lu" <hjl.tools at gmail.com>
> Cc: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan at intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>

Yep, lgtm


Reviewed-by: Sean Paul <seanpaul at chromium.org>

> ---
>  drivers/gpu/drm/drm_connector.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 5cd61aff7857..8072e6e4c62c 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1293,21 +1293,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>  	if (!connector)
>  		return -ENOENT;
>  
> -	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> -	encoder = drm_connector_get_encoder(connector);
> -	if (encoder)
> -		out_resp->encoder_id = encoder->base.id;
> -	else
> -		out_resp->encoder_id = 0;
> -
> -	ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
> -			(uint32_t __user *)(unsigned long)(out_resp->props_ptr),
> -			(uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
> -			&out_resp->count_props);
> -	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> -	if (ret)
> -		goto out_unref;
> -
>  	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++)
>  		if (connector->encoder_ids[i] != 0)
>  			encoders_count++;
> @@ -1320,7 +1305,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>  				if (put_user(connector->encoder_ids[i],
>  					     encoder_ptr + copied)) {
>  					ret = -EFAULT;
> -					goto out_unref;
> +					goto out;
>  				}
>  				copied++;
>  			}
> @@ -1364,15 +1349,32 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>  			if (copy_to_user(mode_ptr + copied,
>  					 &u_mode, sizeof(u_mode))) {
>  				ret = -EFAULT;
> +				mutex_unlock(&dev->mode_config.mutex);
> +
>  				goto out;
>  			}
>  			copied++;
>  		}
>  	}
>  	out_resp->count_modes = mode_count;
> -out:
>  	mutex_unlock(&dev->mode_config.mutex);
> -out_unref:
> +
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +	encoder = drm_connector_get_encoder(connector);
> +	if (encoder)
> +		out_resp->encoder_id = encoder->base.id;
> +	else
> +		out_resp->encoder_id = 0;
> +
> +	/* Only grab properties after probing, to make sure EDID and other
> +	 * properties reflect the latest status. */
> +	ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
> +			(uint32_t __user *)(unsigned long)(out_resp->props_ptr),
> +			(uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
> +			&out_resp->count_props);
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> +out:
>  	drm_connector_put(connector);
>  
>  	return ret;
> -- 
> 2.11.0

-- 
Sean Paul, Software Engineer, Google / Chromium OS