[Intel-gfx] [PATCH 07/14] drm: Only do the hw.lock cleanup in master_relase for !MODESET

[Daniel Vetter]

On Wed, Jun 15, 2016 at 12:48:23PM +0100, Chris Wilson wrote:
> On Tue, Jun 14, 2016 at 08:51:02PM +0200, Daniel Vetter wrote:
> > Another place gone where modern drivers could have hit
> > dev->struct_mutex.
> > 
> > To avoid too deeply nesting control flow rework it a bit.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/drm_auth.c | 20 ++++++++++++--------
> >  1 file changed, 12 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
> > index e015a7edb154..a58b2eb0d004 100644
> > --- a/drivers/gpu/drm/drm_auth.c
> > +++ b/drivers/gpu/drm/drm_auth.c
> > @@ -246,11 +246,14 @@ int drm_master_open(struct drm_file *file_priv)
> >  void drm_master_release(struct drm_file *file_priv)
> >  {
> >  	struct drm_device *dev = file_priv->minor->dev;
> > +	struct drm_master *master = file_priv->master;
> > +
> 
> Spare newline.
> 
> >  	mutex_lock(&dev->master_mutex);
> > -	if (file_priv->is_master) {
> > -		struct drm_master *master = file_priv->master;
> > +	if (!file_priv->is_master)
> > +		goto out_unlock;
> >  
> > +	if (!drm_core_check_feature(dev, DRIVER_MODESET)) {
> >  		/*
> >  		 * Since the master is disappearing, so is the
> >  		 * possibility to lock.
> > @@ -264,19 +267,20 @@ void drm_master_release(struct drm_file *file_priv)
> >  			wake_up_interruptible_all(&master->lock.lock_queue);
> >  		}
> >  		mutex_unlock(&dev->struct_mutex);
> > +	}
> >  
> > -		if (file_priv->minor->master == file_priv->master) {
> > -			/* drop the reference held my the minor */
> > -			if (dev->driver->master_drop)
> > -				dev->driver->master_drop(dev, file_priv, true);
> > -			drm_master_put(&file_priv->minor->master);
> > -		}
> > +	if (file_priv->minor->master == file_priv->master) {
> > +		/* drop the reference held my the minor */
> > +		if (dev->driver->master_drop)
> > +			dev->driver->master_drop(dev, file_priv, true);
> > +		drm_master_put(&file_priv->minor->master);
> >  	}
> >  
> >  	/* drop the master reference held by the file priv */
> >  	if (file_priv->master)
> >  		drm_master_put(&file_priv->master);
> >  	file_priv->is_master = 0;
> > +out_unlock:
> 
> This changes the reference counting, and from my quick scan we can have
> a reference on file_priv->master but file_priv->is_master == 0.

Indeed, I've created a leak. Will fix.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch