Multiple simultaneous masters?

[Thomas Hellstrom]

It turns out that if we have two clients, one opening /dev/dri/card0 and
one opending /dev/dri/controlD64, both will attempt to become active master.

That seems a little illogical to me (and makes the vmwgfx driver BUG).
Shouldn't we have at most one active master per device, and hence
attempt to replace

file_priv->minor->master with
file_priv->minor->dev->active_master

/Thomas