On Tue Feb 3, 2026 at 3:46 PM GMT, Matthew Maurer wrote:
> This adds support for creating a DebugFS directory which is aware that
> it is bound to a device. As a result, callbacks under that directory
> have access to a bound device which gives them efficient access to other
> Devres, ability to use dev_err! and friends, etc.
>
> Signed-off-by: Matthew Maurer <[email protected]>
> ---
> rust/kernel/debugfs.rs | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/rust/kernel/debugfs.rs b/rust/kernel/debugfs.rs
> index
> d7b8014a6474698235203f2b7d8fec96f2bb43f8..ac614d693fa73929d095b669e9ba61958bec609e
> 100644
> --- a/rust/kernel/debugfs.rs
> +++ b/rust/kernel/debugfs.rs
> @@ -11,6 +11,11 @@
> #[cfg(CONFIG_DEBUG_FS)]
> use crate::sync::Arc;
> use crate::{
> + device::{
> + Bound,
> + Device, //
> + },
> + devres::Devres,
> fmt,
> prelude::*,
> str::CStr,
> @@ -722,3 +727,38 @@ fn new(name: &CStr) -> ScopedDir<'data, 'static> {
> }
> }
> }
> +
> +impl<'a, T: 'a + Send> Devres<Scope<T>> {
> + /// Creates a new scope, which is a directory at the root of the debugfs
> filesystem,
> + /// associated with some data `T`, enclosed in a [`Devres`] for the
> provided device.
> + ///
> + /// The `init` closure is called to populate the directory with files
> and subdirectories. These
> + /// files can reference the data stored in the scope. Because it is
> stored inside a `Devres`,
> + /// the init method is granted access to a `&Device<Bound>`.
> + ///
> + /// This can be used for cheaply accessing device-protected data inside
> DebugFS methods or
> + /// accessing device-specific methods (e.g. [`dev_err!`]).
> + ///
> + /// The entire directory tree created within the scope will be removed
> when the returned
> + /// `Scope` handle is dropped.
> + pub fn dir<E: 'a, F>(
> + dev: &'a Device<Bound>,
> + data: impl PinInit<T, E> + 'a,
> + name: &'a CStr,
> + init: F,
> + ) -> impl PinInit<Self, Error> + 'a
> + where
> + F: for<'data, 'dir> FnOnce(&'data T, &'data Device<Bound>, &'dir
> ScopedDir<'data, 'dir>)
> + + 'a,
> + Error: From<E>,
> + {
> + Devres::new(
> + dev,
> + Scope::new(data, |data| {
> + let scoped = ScopedDir::new(name);
> + init(data, dev, &scoped);
> + scoped.into_entry()
> + }),
> + )
> + }
> +}
I think it is a big strange to have this on `Devres` (in patch v6 it has
`Devres::dir` doesn't make
too much sense). I would suggest that we domsomething like
impl<'a, T: 'a + Send> Scope<T> {
pub fn devres_dir(
...
) -> impl PinInit<Devres<Self>, Error> + 'a;
}
To me `Devres` is just a generic container type, just like `Arc` and `ARef`, so
the assoc functions should be defined on the concrete type.
Also: is there a reason that this needs a special API, and by
Devres::new(device, Scope::dir(data, c"name", |data| {
// use data and device
});
?
Best,
Gary
