Commit 2cc107dc authored Sep 01, 2016 by David Herrmann Committed by Daniel Vetter Sep 19, 2016

drm: cleanup drm_core_{init,exit}()



Various cleanups to the DRM core initialization and exit handlers:

 - Register chrdev last: Once register_chrdev() returns, open() will
   succeed on the given chrdevs. This is usually not an issue, as no
   chardevs are registered, yet. However, nodes can be created by
   user-space via mknod(2), even though such major/minor combinations are
   unknown to the kernel. Avoid calling into drm_stub_open() in those
   cases.
   Again, drm_stub_open() would just bail out as the inode is unknown,
   but it's really non-obvious if you hack on drm_stub_open().

 - Unify error-paths into just one label. All the error-path helpers can
   be called even though the constructors were not called yet, or failed.
   Hence, just call all cleanups unconditionally.

 - Call into drm_global_release(). This is a no-op, but provides
   debugging helpers in case there're GLOBALS left on module unload. This
   function was unused until now.

 - Use DRM_ERROR() instead of printk(), and also print the error-code on
   failure (even if it is static!).

 - Don't throw away error-codes of register_chrdev()!

 - Don't hardcode -1 as errno. This is just plain wrong.

 - Order exit-handlers in the exact reverse order of initialization
   (except if the order actually matters for syncing-reasons, which is
   not the case here, though).

v2:
 - Call drm_core_exit() directly from the init-error-handler. Requires to
   drop __exit annotation, though.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20160901124837.680-7-dh.herrmann@gmail.com

parent 82d5e73f

drivers/gpu/drm/drm_drv.c

+22 −26

Original line number	Diff line number	Diff line
		@@ -820,52 +820,48 @@ static const struct file_operations drm_stub_fops = {
		.llseek = noop_llseek,
		};

		static void drm_core_exit(void)
		{
		unregister_chrdev(DRM_MAJOR, "drm");
		debugfs_remove(drm_debugfs_root);
		drm_sysfs_destroy();
		idr_destroy(&drm_minors_idr);
		drm_connector_ida_destroy();
		drm_global_release();
		}

		static int __init drm_core_init(void)
		{
		int ret = -ENOMEM;
		int ret;

		drm_global_init();
		drm_connector_ida_init();
		idr_init(&drm_minors_idr);

		if (register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops))
		goto err_p1;

		ret = drm_sysfs_init();
		if (ret < 0) {
		printk(KERN_ERR "DRM: Error creating drm class.\n");
		goto err_p2;
		DRM_ERROR("Cannot create DRM class: %d\n", ret);
		goto error;
		}

		drm_debugfs_root = debugfs_create_dir("dri", NULL);
		if (!drm_debugfs_root) {
		DRM_ERROR("Cannot create /sys/kernel/debug/dri\n");
		ret = -1;
		goto err_p3;
		ret = -ENOMEM;
		DRM_ERROR("Cannot create debugfs-root: %d\n", ret);
		goto error;
		}

		ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
		if (ret < 0)
		goto error;

		DRM_INFO("Initialized\n");
		return 0;
		err_p3:
		drm_sysfs_destroy();
		err_p2:
		unregister_chrdev(DRM_MAJOR, "drm");

		idr_destroy(&drm_minors_idr);
		err_p1:
		error:
		drm_core_exit();
		return ret;
		}

		static void __exit drm_core_exit(void)
		{
		debugfs_remove(drm_debugfs_root);
		drm_sysfs_destroy();

		unregister_chrdev(DRM_MAJOR, "drm");

		drm_connector_ida_destroy();
		idr_destroy(&drm_minors_idr);
		}

		module_init(drm_core_init);
		module_exit(drm_core_exit);

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