drm/fb-helper: generic: Don't take module ref for fbcon

[ Upstream commit 6ab20a05 ]

It's now safe to let fbcon unbind automatically on fbdev unregister.
The crash problem was fixed in commit 2122b405
("fbdev: fbcon: Fix unregister crash when more than one framebuffer")
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190210131039.52664-13-noralf@tronnes.orgSigned-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/gpu/drm/drm_fb_helper.c

@@ -2957,7 +2957,8 @@ static int drm_fbdev_fb_open(struct fb_info *info, int user)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 
-	if (!try_module_get(fb_helper->dev->driver->fops->owner))
+	/* No need to take a ref for fbcon because it unbinds on unregister */
+	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
 		return -ENODEV;
 
 	return 0;
@@ -2967,7 +2968,8 @@ static int drm_fbdev_fb_release(struct fb_info *info, int user)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 
-	module_put(fb_helper->dev->driver->fops->owner);
+	if (user)
+		module_put(fb_helper->dev->driver->fops->owner);
 
 	return 0;
 }