Re: [PATCH v2] mmc: block: fix RPMB device unregister ordering

[Ulf Hansson]

On Mon, Jul 6, 2026 at 1:43 PM Ao Sun <ao.sun@xxxxxxxxxxxxx> wrote:
>
> From: Ao Sun <ao.sun@xxxxxxxxxxxxx>
>
> Since commit 7852028a35f0 ("mmc: block: register RPMB partition with
> the RPMB subsystem"), each mmc RPMB partition is represented by two
> device objects:
>  - the mmc-owned device (`rpmb->dev`, backing the legacy /dev/mmcblkXrpmb
>    char device) and
>  - the rpmb-core device (`rdev`, backing /dev/rpmbN).
>
> The child RPMB device holds a reference to its parent, so the
> parent's release callback cannot be invoked if the child device
> is still registered.
>
> Remove rpmb_dev_unregister() from the parent release handler and
> unregister the child RPMB device in the remove path before tearing
> down the parent device.
>
> Also delete the extra blank line between mmc_blk_remove_rpmb_part()
> and {.
>
> Fixes: 7852028a35f0 ("mmc: block: register RPMB partition with the RPMB subsystem")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jiazi Li <jiazi.li@xxxxxxxxxxxxx>
> Signed-off-by: Ao Sun <ao.sun@xxxxxxxxxxxxx>
> Reviewed-by: Avri Altman <avri.altman@xxxxxxxxxxx>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
> Changes in v2:
>   - add background describing the two RPMB device objects
>   - add Fixes and Cc
>   - collect Reviewed-by
> ---
>  drivers/mmc/core/block.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 0274e8d07660..54a923ba4f1e 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -2715,7 +2715,6 @@ static void mmc_blk_rpmb_device_release(struct device *dev)
>  {
>         struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
>
> -       rpmb_dev_unregister(rpmb->rdev);
>         mmc_blk_put(rpmb->md);
>         ida_free(&mmc_rpmb_ida, rpmb->id);
>         kfree(rpmb);
> @@ -2930,8 +2929,8 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
>  }
>
>  static void mmc_blk_remove_rpmb_part(struct mmc_rpmb_data *rpmb)
> -
>  {
> +       rpmb_dev_unregister(rpmb->rdev);
>         cdev_device_del(&rpmb->chrdev, &rpmb->dev);
>         put_device(&rpmb->dev);
>  }
> --
> 2.34.1
>