drm/sun4i: Fix crash during suspend after component bind failure

If the component driver fails to bind, or is unbound, the driver data
for the top-level platform device points to a freed drm_device. If the
system is then suspended, the driver passes this dangling pointer to
drm_mode_config_helper_suspend(), which crashes.

Fix this by only setting the driver data while the platform driver holds
a reference to the drm_device.

Fixes: 624b4b48d9d8 ("drm: sun4i: Add support for suspending the display driver")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220615054254.16352-1-samuel@sholland.org

diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c b/drivers/gpu/drm/sun4i/sun4i_drv.c
index 275f7e4..8841dba 100644 (file)
--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
@@ -73,7 +73,6 @@ static int sun4i_drv_bind(struct device *dev)
                goto free_drm;
        }
 
-       dev_set_drvdata(dev, drm);
        drm->dev_private = drv;
        INIT_LIST_HEAD(&drv->frontend_list);
        INIT_LIST_HEAD(&drv->engine_list);
@@ -114,6 +113,8 @@ static int sun4i_drv_bind(struct device *dev)
 
        drm_fbdev_generic_setup(drm, 32);
 
+       dev_set_drvdata(dev, drm);
+
        return 0;
 
 finish_poll:
@@ -130,6 +131,7 @@ static void sun4i_drv_unbind(struct device *dev)
 {
        struct drm_device *drm = dev_get_drvdata(dev);
 
+       dev_set_drvdata(dev, NULL);
        drm_dev_unregister(drm);
        drm_kms_helper_poll_fini(drm);
        drm_atomic_helper_shutdown(drm);