Re: [PATCH 10/14] scsi: osd: fix device_register() error handling

Dan Carpenter
2010-09-19T14:26:53Z

On Sun, Sep 19, 2010 at 04:55:07PM +0400, Vasiliy Kulikov wrote:
> If device_register() fails then call put_device().
> See comment to device_register.
>
> Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
> ---
> compile tested.
>
> drivers/scsi/osd/osd_uld.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/osd/osd_uld.c b/drivers/scsi/osd/osd_uld.c
> index cefb2c0..3e0edc2 100644
> --- a/drivers/scsi/osd/osd_uld.c
> +++ b/drivers/scsi/osd/osd_uld.c
> @@ -474,7 +474,7 @@ static int osd_probe(struct device *dev)
> error = device_register(&oud->class_dev);
> if (error) {
> OSD_ERR("device_register failed => %d\n", error);
> - goto err_put_cdev;
> + goto err_put_device;
> }
>
> get_device(&oud->class_dev);
> @@ -482,6 +482,8 @@ static int osd_probe(struct device *dev)
> OSD_INFO("osd_probe %s\n", disk->disk_name);
> return 0;
>

Hm... So if device_register() fails then we should always call
device_put()? It seems like a lot of existing code does that but I
hadn't realized until now that that is how it works.

Why can't the device_put() just be added inside the device_register() so
the unwinding works automatically?

Also if someone add some more stuff to the end of this function, will
the device_unregister() followed by a device_put() cause problems if we
unwind like this?

+err_free_something:
+ kfree(foo);
+ device_unregister(&oud->class_dev);
> +err_put_device:
> + put_device(&oud->class_dev);
> err_put_cdev:
> cdev_del(&oud->cdev);
> err_put_disk:

If that's the case then the put_device() should be called infront of the
goto.

regards,
dan carpenter