[PATCH 06/19] drm/vmwgfx: Drop the cursor locking hack

[Daniel Vetter]

On Thu, Mar 23, 2017 at 07:22:31AM +0100, Thomas Hellstrom wrote:
> On 03/22/2017 10:50 PM, Daniel Vetter wrote:
> > It's been around forever, no one bothered to address the FIXME, so I
> > presume it's all fine.
> >
> > Cc: Sinclair Yeh <syeh at vmware.com>
> > Cc: Thomas Hellstrom <thellstrom at vmware.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> 
> NAK. We need to properly address this. Probably as part of the atomic
> update.

So could someone with vmwgfx understanding explain this? Note that the
FIXME was originally added by me years ago, because I wasn't sure (only
about 90%) that this is safe, and was essentially pleading for a vmwgfx
expert to review this?

Since it didn't happen I presume it's not that terribly and probably safe
...

I'm still 90% sure that this is correct, but I'd love for a vmwgfx to
audit it. Replying with a NAK is kinda not the response I was hoping for
(and yes I guess I should have explained what's going on here better, but
it's just a git blame of the FIXME comment away).

Thanks,

Daniel

> /Thomas
> 
> 
> 
> > ---
> >  drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 25 -------------------------
> >  1 file changed, 25 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> > index d492d57d5309..424b3fc57203 100644
> > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> > @@ -148,15 +148,6 @@ int vmw_du_crtc_cursor_set2(struct drm_crtc *crtc, struct drm_file *file_priv,
> >  	s32 hotspot_x, hotspot_y;
> >  	int ret;
> >  
> > -	/*
> > -	 * FIXME: Unclear whether there's any global state touched by the
> > -	 * cursor_set function, especially vmw_cursor_update_position looks
> > -	 * suspicious. For now take the easy route and reacquire all locks. We
> > -	 * can do this since the caller in the drm core doesn't check anything
> > -	 * which is protected by any looks.
> > -	 */
> > -	drm_modeset_unlock_crtc(crtc);
> > -	drm_modeset_lock_all(dev_priv->dev);
> >  	hotspot_x = hot_x + du->hotspot_x;
> >  	hotspot_y = hot_y + du->hotspot_y;
> >  
> > @@ -224,9 +215,6 @@ int vmw_du_crtc_cursor_set2(struct drm_crtc *crtc, struct drm_file *file_priv,
> >  	}
> >  
> >  out:
> > -	drm_modeset_unlock_all(dev_priv->dev);
> > -	drm_modeset_lock_crtc(crtc, crtc->cursor);
> > -
> >  	return ret;
> >  }
> >  
> > @@ -239,25 +227,12 @@ int vmw_du_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
> >  	du->cursor_x = x + du->set_gui_x;
> >  	du->cursor_y = y + du->set_gui_y;
> >  
> > -	/*
> > -	 * FIXME: Unclear whether there's any global state touched by the
> > -	 * cursor_set function, especially vmw_cursor_update_position looks
> > -	 * suspicious. For now take the easy route and reacquire all locks. We
> > -	 * can do this since the caller in the drm core doesn't check anything
> > -	 * which is protected by any looks.
> > -	 */
> > -	drm_modeset_unlock_crtc(crtc);
> > -	drm_modeset_lock_all(dev_priv->dev);
> > -
> >  	vmw_cursor_update_position(dev_priv, shown,
> >  				   du->cursor_x + du->hotspot_x +
> >  				   du->core_hotspot_x,
> >  				   du->cursor_y + du->hotspot_y +
> >  				   du->core_hotspot_y);
> >  
> > -	drm_modeset_unlock_all(dev_priv->dev);
> > -	drm_modeset_lock_crtc(crtc, crtc->cursor);
> > -
> >  	return 0;
> >  }
> >  
> 
> 

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