[PATCH 5.0 340/346] drm/drv: Hold ref on parent device during drm_device lifetime

[Greg Kroah-Hartman]

[ Upstream commit 56be6503aab2bc3a30beae408071b9be5e1bae51 ]

This makes it safe to access drm_device->dev after the parent device has
been removed/unplugged.

Signed-off-by: Noralf TrÃnnes <noralf@xxxxxxxxxxx>
Reviewed-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20190225144232.20761-2-noralf@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_drv.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7a59b8b3ed5a4..81c8936bc1d3c 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -499,7 +499,7 @@ int drm_dev_init(struct drm_device *dev,
 	BUG_ON(!parent);
 
 	kref_init(&dev->ref);
-	dev->dev = parent;
+	dev->dev = get_device(parent);
 	dev->driver = driver;
 
 	/* no per-device feature limits by default */
@@ -569,6 +569,7 @@ int drm_dev_init(struct drm_device *dev,
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 	drm_fs_inode_free(dev->anon_inode);
 err_free:
+	put_device(dev->dev);
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
@@ -604,6 +605,8 @@ void drm_dev_fini(struct drm_device *dev)
 	drm_minor_free(dev, DRM_MINOR_PRIMARY);
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 
+	put_device(dev->dev);
+
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
-- 
2.20.1