Re: [PATCH v2 06/16] tpm-chip: utilize new cdev_device_add helper function

Jason Gunthorpe
2017-02-27T16:42:09Z

On Sat, Feb 25, 2017 at 11:38:07PM -0700, Logan Gunthorpe wrote:
> Replace the open coded registration of the cdev and dev with the
> new device_add_cdev() helper. The helper replaces a common pattern by
> taking the proper reference against the parent device and adding both
> the cdev and the device.
>
> Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
> drivers/char/tpm/tpm-chip.c | 19 +++----------------
> 1 file changed, 3 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index a77262d..933f96e 100644
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -187,7 +187,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *dev,
>
> cdev_init(&chip->cdev, &tpm_fops);
> chip->cdev.owner = THIS_MODULE;
> - chip->cdev.kobj.parent = &chip->dev.kobj;
>
> return chip;
>
> @@ -230,27 +229,16 @@ static int tpm_add_char_device(struct tpm_chip *chip)
> {
> int rc;
>
> - rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
> + rc = cdev_device_add(&chip->cdev, &chip->dev);
> if (rc) {
> dev_err(&chip->dev,
> - "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
> + "unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
> dev_name(&chip->dev), MAJOR(chip->dev.devt),
> MINOR(chip->dev.devt), rc);
>
> return rc;
> }
>
> - rc = device_add(&chip->dev);
> - if (rc) {
> - dev_err(&chip->dev,
> - "unable to device_register() %s, major %d, minor %d, err=%d\n",
> - dev_name(&chip->dev), MAJOR(chip->dev.devt),
> - MINOR(chip->dev.devt), rc);
> -
> - cdev_del(&chip->cdev);
> - return rc;
> - }

This will collide with the patch I sent:

https://patchwork.kernel.org/patch/9589001/

Jarkko: The resolution will be to continue to call tpm_del_char_device
from the cdev_device_add error path and drop all calls to cdev_del

Reviewed-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>

Jason