[PATCH 2/2] drm/vkms: Use drm_dev_unplug() for ConfigFS device removal

[Sebastian Wick]

VKMS ConfigFS devices can be disabled while userspace still holds open
file descriptors. Using drm_dev_unregister() leaves the device in a
state where ioctls are still accepted but internal locks can contend
with the teardown path. Specifically, drmModeGetConnector() triggers
fill_modes which acquires mode_config locks that contend with
drm_atomic_helper_shutdown().

Use drm_dev_unplug() instead, which marks the device as unplugged so
the ioctl layer rejects subsequent calls with -ENODEV. The previous
commit added drm_dev_enter()/drm_dev_exit() guards to vkms callbacks,
so synchronize_srcu() in drm_dev_unplug() properly waits for any
in-flight operations before the teardown proceeds.

Signed-off-by: Sebastian Wick <sebastian.wick@xxxxxxxxxx>
---
 drivers/gpu/drm/vkms/vkms_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 5a640b531d88..716f9c966c21 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -259,7 +259,7 @@ void vkms_destroy(struct vkms_config *config)
 
 	fdev = config->dev->faux_dev;
 
-	drm_dev_unregister(&config->dev->drm);
+	drm_dev_unplug(&config->dev->drm);
 	drm_atomic_helper_shutdown(&config->dev->drm);
 	devres_release_group(&fdev->dev, NULL);
 	faux_device_destroy(fdev);
-- 
2.56.0