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? -Daniel
drivers/gpu/drm/drm_drv.c | 6 +++--- drivers/gpu/drm/drm_file.c | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index b5c6bb46a425..30b5382bf877 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -364,9 +364,9 @@ void drm_unplug_dev(struct drm_device *dev)
drm_device_set_unplugged(dev);
- if (dev->open_count == 0) {
drm_put_dev(dev);- }
- if (dev->open_count == 0)
drm_dev_unref(dev);- mutex_unlock(&drm_global_mutex);
} EXPORT_SYMBOL(drm_unplug_dev); diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c index 3783b659cd38..edba71c8ccc3 100644 --- a/drivers/gpu/drm/drm_file.c +++ b/drivers/gpu/drm/drm_file.c @@ -424,7 +424,7 @@ int drm_release(struct inode *inode, struct file *filp) if (!--dev->open_count) { drm_lastclose(dev); if (drm_device_is_unplugged(dev))
drm_put_dev(dev);
drm_dev_unref(dev);-- 2.13.0
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