[PATCH] drm: Fix GETCONNECTOR regression

[Daniel Vetter]

On Tue, Jun 20, 2017 at 05:40:25PM -0400, Sean Paul wrote:
> 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>

Pushed to -fixes, thanks for the review.
-Daniel


> 
> > ---
> >  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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch