On Mon, May 29, 2017 at 09:02:38PM +0200, Daniel Vetter wrote:
On Sun, May 28, 2017 at 07:16:55PM +0200, Hans de Goede wrote:
Since commit a39be606f99d ("drm: Do a full device unregister when unplugging") drm_unplug_dev has been calling drm_dev_unregister followed by a drm_put_dev when open_count reaches 0. This drm_put_dev calls drm_dev_unregister again. Since drm_dev_unregister is not protected against being called multiple times this leads to havoc.
This commit fixes this by calling drm_dev_unref instead of drm_put_dev.
Fixes: a39be606f99d ("drm: Do a full device unregister when unplugging") Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Marco Diego Aurélio Mesquita marcodiegomesquita@gmail.com Reported-by: Marco Diego Aurélio Mesquita marcodiegomesquita@gmail.com Signed-off-by: Hans de Goede hdegoede@redhat.com
Note I don't have any USB display devices at hand for testing atm so this patch has only been compile tested.
Changes in v2: -Remove unnecessary mutex changes
Offending patch is in 4.8 ... do we need cc: stable? Does this need a bugreport link?
One more: When fixing a regression pls cc author/reviewer of the offending patch, for the learning. Adding Chris. -Daniel