On Thu Jul 30, 2026 at 7:05 PM CEST, Alvin Sun wrote:
> + /// Creates a [`ScopedDir`] wrapping an existing debugfs dentry.
> + ///
> + /// Files created under this directory are not automatically removed on
> drop;
> + /// their lifetime is tied to the dentry owner.
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure the dentry remains valid for the lifetime of
> the
> + /// returned `ScopedDir`.
> + pub unsafe fn from_dentry(dentry: *mut bindings::dentry) -> Self {
> + let _ = dentry;
> + ScopedDir {
> + #[cfg(CONFIG_DEBUG_FS)]
> + // SAFETY: The caller guarantees the dentry is valid and
> outlives this `ScopedDir`.
> + entry: ManuallyDrop::new(unsafe { Entry::from_raw(dentry) }),
> + _phantom: PhantomData,
> + }
> + }
I think what you actually want to express is that the DRM debugfs root dir
represents a view into an existing scope, where the data is T::RegistrationData.
Additionally, we want to be able to derive new debugfs::Scopes from this that
are shorter lived, so we can create new debugfs::Scopes e.g. in
drm::DriverFile<'a>, which I currently work on.
So, what I'm thinking of is a type like:
pub struct ScopeRef<'a, T> {
#[cfg(CONFIG_DEBUG_FS)]
dentry: Option<NonNull<bindings::dentry>>,
data: &'a T,
}
which has a corresponding unsafe constructor and provides methods to e.g. create
a new directory, returning a new ScopeRef<'a, T>, which can be stored in
lifetime scoped data.
Additionally, but that's somewhat orthogonal, we want debugfs::Scope to support
lifetime data, so a scope can participate in the driver lifecycle; the
corresponding synchronization is already in place with full proxy fops.
