Re: [PATCH 3/6] drm: Define a conditional guard for drm_dev_{enter,exit}()

[Chia-I Wu]

On Wed, May 13, 2026 at 10:24 AM Boris Brezillon
<boris.brezillon@xxxxxxxxxxxxx> wrote:
>
> Define a conditional drm_dev_access guard to automate the
> drm_dev_{enter,exit}() sequence.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> ---
>  include/drm/drm_drv.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 42fc085f986d..79d1958f93e4 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -490,6 +490,15 @@ void drm_dev_unplug(struct drm_device *dev);
>  int drm_dev_wedged_event(struct drm_device *dev, unsigned long method,
>                          struct drm_wedge_task_info *info);
>
> +/*
> + * Only the conditional drm_dev_access guard is valid. The drm_dev one is
> + * here so we can extend it with a conditional variant.
> + */
> +DEFINE_LOCK_GUARD_1(drm_dev, struct drm_device,
> +                   { WARN_ON("Use cond guards"); _T->idx = -1; },
> +                   drm_dev_exit(_T->idx), int idx);
If this is ever mis-used, drm_dev_exit(-1) seems to cause OOB access.
Is BUG more appropriate than WARN_ON?

> +DEFINE_LOCK_GUARD_1_COND(drm_dev, _access, drm_dev_enter(_T->lock, &_T->idx));
> +
>  /**
>   * drm_dev_is_unplugged - is a DRM device unplugged
>   * @dev: DRM device
>
> --
> 2.54.0
>