* [PATCH v8 0/3] rust: configfs abstractions
@ 2025-05-08 8:52 Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 1/3] rust: configfs: introduce rust support for configfs Andreas Hindborg
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Andreas Hindborg @ 2025-05-08 8:52 UTC (permalink / raw)
To: Danilo Krummrich, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Alice Ryhl, Trevor Gross,
Joel Becker, Peter Zijlstra, Ingo Molnar, Will Deacon,
Waiman Long, Fiona Behrens, Charalampos Mitrodimas,
Daniel Almeida, Breno Leitao
Cc: rust-for-linux, linux-kernel, Andreas Hindborg
Add a safe Rust API that allows Rust modules to interface the `configfs`
machinery.
Add an example for the samples folder to demonstrate usage of the API.
Add a maintainer entry for the Rust configfs abstractions in the last patch, to
make it absolutely clear that I will commit to maintain these abstractions, if
required.
The series is a dependency of `rnull`, the Rust null block driver.
Please see [1] for initial `configfs` support in `rnull`.
[1] https://github.com/metaspace/linux/tree/9ac53130f5fb05b9b3074fa261b445b8fde547dd/drivers/block/rnull
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
Changes in v8:
- Fix a reasoning error in the safety comment framework for
`AttributeList::add`.
- Link to v7: https://lore.kernel.org/r/20250505-configfs-v7-0-8bcf47c1fb88@kernel.org
Changes in v7:
- Update documentation: Consistently apply code spans, add inter-doc
links, fix typos and improve indentation.
- Use a const block to verify attribute index.
- Link to v6: https://lore.kernel.org/r/20250501-configfs-v6-0-66c61eb76368@kernel.org
Changes in v6:
- Use `&raw const` and `&raw mut` instead of `addr_of!` and
`addr_of_mut!` macros.
- Drop use of `ForeignOwnable`.
- Link to v5: https://lore.kernel.org/r/20250227-configfs-v5-0-c40e8dc3b9cd@kernel.org
Changes in v5:
- Remove `as _` casts.
- Document `ID` type parameter of `AttributeOperations`.
- Add documentation at macro call sites in example.
- Add example expansion of `configfs_attrs!`.
- Move trait bound in `AttributeList::add`
- Improve safety requirement for `AttributeList::new`.
- Fix a copy/paste error in print in sample.
- Clarify use of `{}` for empty struct in sample.
- Improve documentation for `AttributeList`.
- Remove `kernel::` prefix from `container_of!` invocation.
- Reword safety comment in `get_group_data`.
- Correct commit message in relation to unstable feature additions.
- Use imperative language in commit messages.
- Consistently capitalize the word "Rust" in commit messages.
- Explain that "drop" in `GroupOperations::drop_item` is not related to Rust
drop.
- Link to v4: https://lore.kernel.org/r/20250224-configfs-v4-0-9af9b5e611f6@kernel.org
Changes in v4:
- Fix a build issue by depending on v18 of "rust: types: add `ForeignOwnable::PointedTo`"
- Link to v3: https://lore.kernel.org/r/20250218-configfs-v3-0-0e40c0778187@kernel.org
Changes in v3:
- Allow trailing commas in invocation of `configfs_attrs!`.
- Use a more suitable C initialization function when initializing `Subsystem`.
- Split sample into separate patch.
- Add an inline example.
The remaining changes in this version are style fixes, documentation
improvements and typo fixes. They are enumerated below:
- Consolidate `paste` macro calls.
- Do not hard code page size in example.
- Remove prefix of `c_str!` in sample.
- Use a more descriptive variable name in `into_foreign`.
- Improve code formatting in macros invocations.
- Add comment related to null terminator in `configfs_attrs!`
- Move attributes below docstrings.
- Remove a rogue todo.
- Remove trait bound from struct definition `GroupOperationsVTable`.
- Remove `as _` casts.
- Remove `GroupOprations::Parent` associated type.
- General documentation improvements.
- Explicitly use `ArcBorrow` for `drop_item` parameter type.
- Add a comment describing expansion to a call to `Attribute::add`.
- Add a comment explaining bound check in `Attribute::add`.
- Link to v2: https://lore.kernel.org/r/20250207-configfs-v2-0-f7a60b24d38e@kernel.org
Changes in v2:
- Remove generalization over pointer type and enforce use of `Arc`.
- Use type system to enforce connection between `ItemType` and
`Subsystem` or `Group`. Differentiate construction of vtables on this
type difference.
- Move drop logic of child nodes from parent to child.
- Pick `ForeignOwnable::PointedTo` patch as dependency instead of
including it here.
- Fix some rustdoc warnings.
- Use CamelCase for generic type parameter declaration.
- Destroy mutex in `Subsystem::drop`.
- Move `GroupOperationsVTable` struct definition next to implementation.
- Rebase on v6.14-rc1.
- Link to v1: https://lore.kernel.org/r/20250131-configfs-v1-0-87947611401c@kernel.org
---
Andreas Hindborg (3):
rust: configfs: introduce rust support for configfs
rust: configfs: add a sample demonstrating configfs usage
MAINTAINERS: add configfs Rust abstractions
MAINTAINERS | 2 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/mutex.c | 5 +
rust/kernel/configfs.rs | 1049 +++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
samples/rust/Kconfig | 11 +
samples/rust/Makefile | 1 +
samples/rust/rust_configfs.rs | 192 +++++++
8 files changed, 1263 insertions(+)
---
base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
change-id: 20250131-configfs-b888cd82d84a
Best regards,
--
Andreas Hindborg <a.hindborg@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v8 1/3] rust: configfs: introduce rust support for configfs
2025-05-08 8:52 [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
@ 2025-05-08 8:52 ` Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 2/3] rust: configfs: add a sample demonstrating configfs usage Andreas Hindborg
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Andreas Hindborg @ 2025-05-08 8:52 UTC (permalink / raw)
To: Danilo Krummrich, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Alice Ryhl, Trevor Gross,
Joel Becker, Peter Zijlstra, Ingo Molnar, Will Deacon,
Waiman Long, Fiona Behrens, Charalampos Mitrodimas,
Daniel Almeida, Breno Leitao
Cc: rust-for-linux, linux-kernel, Andreas Hindborg
Add a Rust API for configfs, thus allowing Rust modules to use configfs for
configuration. Make the implementation a shim on top of the C configfs
implementation, allowing safe use of the C infrastructure from Rust.
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
This patch is a direct dependency for `rnull`, the rust null block driver.
---
rust/bindings/bindings_helper.h | 1 +
rust/helpers/mutex.c | 5 +
rust/kernel/configfs.rs | 1049 +++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
4 files changed, 1057 insertions(+)
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ab37e1d35c70d52e69b754bf855bc19911d156d8..1a532b83a9afedb4965cfaab4bac21adbab2a7de 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -10,6 +10,7 @@
#include <linux/blk-mq.h>
#include <linux/blk_types.h>
#include <linux/blkdev.h>
+#include <linux/configfs.h>
#include <linux/cpumask.h>
#include <linux/cred.h>
#include <linux/device/faux.h>
diff --git a/rust/helpers/mutex.c b/rust/helpers/mutex.c
index 06575553eda5c5a99ab27ef38101f9bf0c7f5644..3e9b910a88e9bc20a283901bb4c846ea2e4a9616 100644
--- a/rust/helpers/mutex.c
+++ b/rust/helpers/mutex.c
@@ -17,3 +17,8 @@ void rust_helper_mutex_assert_is_held(struct mutex *mutex)
{
lockdep_assert_held(mutex);
}
+
+void rust_helper_mutex_destroy(struct mutex *lock)
+{
+ mutex_destroy(lock);
+}
diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs
new file mode 100644
index 0000000000000000000000000000000000000000..b93ac7b0bebc21caea4a6d35f6725b5c900f27ec
--- /dev/null
+++ b/rust/kernel/configfs.rs
@@ -0,0 +1,1049 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! configfs interface: Userspace-driven Kernel Object Configuration
+//!
+//! configfs is an in-memory pseudo file system for configuration of kernel
+//! modules. Please see the [C documentation] for details and intended use of
+//! configfs.
+//!
+//! This module does not support the following configfs features:
+//!
+//! - Items. All group children are groups.
+//! - Symlink support.
+//! - `disconnect_notify` hook.
+//! - Default groups.
+//!
+//! See the [`rust_configfs.rs`] sample for a full example use of this module.
+//!
+//! C header: [`include/linux/configfs.h`](srctree/include/linux/configfs.h)
+//!
+//! # Example
+//!
+//! ```ignore
+//! use kernel::alloc::flags;
+//! use kernel::c_str;
+//! use kernel::configfs_attrs;
+//! use kernel::configfs;
+//! use kernel::new_mutex;
+//! use kernel::page::PAGE_SIZE;
+//! use kernel::sync::Mutex;
+//! use kernel::ThisModule;
+//!
+//! #[pin_data]
+//! struct RustConfigfs {
+//! #[pin]
+//! config: configfs::Subsystem<Configuration>,
+//! }
+//!
+//! impl kernel::InPlaceModule for RustConfigfs {
+//! fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
+//! pr_info!("Rust configfs sample (init)\n");
+//!
+//! let item_type = configfs_attrs! {
+//! container: configfs::Subsystem<Configuration>,
+//! data: Configuration,
+//! attributes: [
+//! message: 0,
+//! bar: 1,
+//! ],
+//! };
+//!
+//! try_pin_init!(Self {
+//! config <- configfs::Subsystem::new(
+//! c_str!("rust_configfs"), item_type, Configuration::new()
+//! ),
+//! })
+//! }
+//! }
+//!
+//! #[pin_data]
+//! struct Configuration {
+//! message: &'static CStr,
+//! #[pin]
+//! bar: Mutex<(KBox<[u8; PAGE_SIZE]>, usize)>,
+//! }
+//!
+//! impl Configuration {
+//! fn new() -> impl PinInit<Self, Error> {
+//! try_pin_init!(Self {
+//! message: c_str!("Hello World\n"),
+//! bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)),
+//! })
+//! }
+//! }
+//!
+//! #[vtable]
+//! impl configfs::AttributeOperations<0> for Configuration {
+//! type Data = Configuration;
+//!
+//! fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+//! pr_info!("Show message\n");
+//! let data = container.message;
+//! page[0..data.len()].copy_from_slice(data);
+//! Ok(data.len())
+//! }
+//! }
+//!
+//! #[vtable]
+//! impl configfs::AttributeOperations<1> for Configuration {
+//! type Data = Configuration;
+//!
+//! fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+//! pr_info!("Show bar\n");
+//! let guard = container.bar.lock();
+//! let data = guard.0.as_slice();
+//! let len = guard.1;
+//! page[0..len].copy_from_slice(&data[0..len]);
+//! Ok(len)
+//! }
+//!
+//! fn store(container: &Configuration, page: &[u8]) -> Result {
+//! pr_info!("Store bar\n");
+//! let mut guard = container.bar.lock();
+//! guard.0[0..page.len()].copy_from_slice(page);
+//! guard.1 = page.len();
+//! Ok(())
+//! }
+//! }
+//! ```
+//!
+//! [C documentation]: srctree/Documentation/filesystems/configfs.rst
+//! [`rust_configfs.rs`]: srctree/samples/rust/rust_configfs.rs
+
+use crate::alloc::flags;
+use crate::container_of;
+use crate::page::PAGE_SIZE;
+use crate::prelude::*;
+use crate::str::CString;
+use crate::sync::Arc;
+use crate::sync::ArcBorrow;
+use crate::types::Opaque;
+use core::cell::UnsafeCell;
+use core::marker::PhantomData;
+
+/// A configfs subsystem.
+///
+/// This is the top level entrypoint for a configfs hierarchy. To register
+/// with configfs, embed a field of this type into your kernel module struct.
+#[pin_data(PinnedDrop)]
+pub struct Subsystem<Data> {
+ #[pin]
+ subsystem: Opaque<bindings::configfs_subsystem>,
+ #[pin]
+ data: Data,
+}
+
+// SAFETY: We do not provide any operations on `Subsystem`.
+unsafe impl<Data> Sync for Subsystem<Data> {}
+
+// SAFETY: Ownership of `Subsystem` can safely be transferred to other threads.
+unsafe impl<Data> Send for Subsystem<Data> {}
+
+impl<Data> Subsystem<Data> {
+ /// Create an initializer for a [`Subsystem`].
+ ///
+ /// The subsystem will appear in configfs as a directory name given by
+ /// `name`. The attributes available in directory are specified by
+ /// `item_type`.
+ pub fn new(
+ name: &'static CStr,
+ item_type: &'static ItemType<Subsystem<Data>, Data>,
+ data: impl PinInit<Data, Error>,
+ ) -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ subsystem <- pin_init::zeroed().chain(
+ |place: &mut Opaque<bindings::configfs_subsystem>| {
+ // SAFETY: We initialized the required fields of `place.group` above.
+ unsafe {
+ bindings::config_group_init_type_name(
+ &mut (*place.get()).su_group,
+ name.as_ptr(),
+ item_type.as_ptr(),
+ )
+ };
+
+ // SAFETY: `place.su_mutex` is valid for use as a mutex.
+ unsafe {
+ bindings::__mutex_init(
+ &mut (*place.get()).su_mutex,
+ kernel::optional_name!().as_char_ptr(),
+ kernel::static_lock_class!().as_ptr(),
+ )
+ }
+ Ok(())
+ }
+ ),
+ data <- data,
+ })
+ .pin_chain(|this| {
+ crate::error::to_result(
+ // SAFETY: We initialized `this.subsystem` according to C API contract above.
+ unsafe { bindings::configfs_register_subsystem(this.subsystem.get()) },
+ )
+ })
+ }
+}
+
+#[pinned_drop]
+impl<Data> PinnedDrop for Subsystem<Data> {
+ fn drop(self: Pin<&mut Self>) {
+ // SAFETY: We registered `self.subsystem` in the initializer returned by `Self::new`.
+ unsafe { bindings::configfs_unregister_subsystem(self.subsystem.get()) };
+ // SAFETY: We initialized the mutex in `Subsystem::new`.
+ unsafe { bindings::mutex_destroy(&raw mut (*self.subsystem.get()).su_mutex) };
+ }
+}
+
+/// Trait that allows offset calculations for structs that embed a
+/// `bindings::config_group`.
+///
+/// Users of the configfs API should not need to implement this trait.
+///
+/// # Safety
+///
+/// - Implementers of this trait must embed a `bindings::config_group`.
+/// - Methods must be implemented according to method documentation.
+pub unsafe trait HasGroup<Data> {
+ /// Return the address of the `bindings::config_group` embedded in [`Self`].
+ ///
+ /// # Safety
+ ///
+ /// - `this` must be a valid allocation of at least the size of [`Self`].
+ unsafe fn group(this: *const Self) -> *const bindings::config_group;
+
+ /// Return the address of the [`Self`] that `group` is embedded in.
+ ///
+ /// # Safety
+ ///
+ /// - `group` must point to the `bindings::config_group` that is embedded in
+ /// [`Self`].
+ unsafe fn container_of(group: *const bindings::config_group) -> *const Self;
+}
+
+// SAFETY: `Subsystem<Data>` embeds a field of type `bindings::config_group`
+// within the `subsystem` field.
+unsafe impl<Data> HasGroup<Data> for Subsystem<Data> {
+ unsafe fn group(this: *const Self) -> *const bindings::config_group {
+ // SAFETY: By impl and function safety requirement this projection is in bounds.
+ unsafe { &raw const (*(*this).subsystem.get()).su_group }
+ }
+
+ unsafe fn container_of(group: *const bindings::config_group) -> *const Self {
+ // SAFETY: By impl and function safety requirement this projection is in bounds.
+ let c_subsys_ptr = unsafe { container_of!(group, bindings::configfs_subsystem, su_group) };
+ let opaque_ptr = c_subsys_ptr.cast::<Opaque<bindings::configfs_subsystem>>();
+ // SAFETY: By impl and function safety requirement, `opaque_ptr` and the
+ // pointer it returns, are within the same allocation.
+ unsafe { container_of!(opaque_ptr, Subsystem<Data>, subsystem) }
+ }
+}
+
+/// A configfs group.
+///
+/// To add a subgroup to configfs, pass this type as `ctype` to
+/// [`crate::configfs_attrs`] when creating a group in [`GroupOperations::make_group`].
+#[pin_data]
+pub struct Group<Data> {
+ #[pin]
+ group: Opaque<bindings::config_group>,
+ #[pin]
+ data: Data,
+}
+
+impl<Data> Group<Data> {
+ /// Create an initializer for a new group.
+ ///
+ /// When instantiated, the group will appear as a directory with the name
+ /// given by `name` and it will contain attributes specified by `item_type`.
+ pub fn new(
+ name: CString,
+ item_type: &'static ItemType<Group<Data>, Data>,
+ data: impl PinInit<Data, Error>,
+ ) -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ group <- pin_init::zeroed().chain(|v: &mut Opaque<bindings::config_group>| {
+ let place = v.get();
+ let name = name.as_bytes_with_nul().as_ptr();
+ // SAFETY: It is safe to initialize a group once it has been zeroed.
+ unsafe {
+ bindings::config_group_init_type_name(place, name.cast(), item_type.as_ptr())
+ };
+ Ok(())
+ }),
+ data <- data,
+ })
+ }
+}
+
+// SAFETY: `Group<Data>` embeds a field of type `bindings::config_group`
+// within the `group` field.
+unsafe impl<Data> HasGroup<Data> for Group<Data> {
+ unsafe fn group(this: *const Self) -> *const bindings::config_group {
+ Opaque::raw_get(
+ // SAFETY: By impl and function safety requirements this field
+ // projection is within bounds of the allocation.
+ unsafe { &raw const (*this).group },
+ )
+ }
+
+ unsafe fn container_of(group: *const bindings::config_group) -> *const Self {
+ let opaque_ptr = group.cast::<Opaque<bindings::config_group>>();
+ // SAFETY: By impl and function safety requirement, `opaque_ptr` and
+ // pointer it returns will be in the same allocation.
+ unsafe { container_of!(opaque_ptr, Self, group) }
+ }
+}
+
+/// # Safety
+///
+/// `this` must be a valid pointer.
+///
+/// If `this` does not represent the root group of a configfs subsystem,
+/// `this` must be a pointer to a `bindings::config_group` embedded in a
+/// `Group<Parent>`.
+///
+/// Otherwise, `this` must be a pointer to a `bindings::config_group` that
+/// is embedded in a `bindings::configfs_subsystem` that is embedded in a
+/// `Subsystem<Parent>`.
+unsafe fn get_group_data<'a, Parent>(this: *mut bindings::config_group) -> &'a Parent {
+ // SAFETY: `this` is a valid pointer.
+ let is_root = unsafe { (*this).cg_subsys.is_null() };
+
+ if !is_root {
+ // SAFETY: By C API contact,`this` was returned from a call to
+ // `make_group`. The pointer is known to be embedded within a
+ // `Group<Parent>`.
+ unsafe { &(*Group::<Parent>::container_of(this)).data }
+ } else {
+ // SAFETY: By C API contract, `this` is a pointer to the
+ // `bindings::config_group` field within a `Subsystem<Parent>`.
+ unsafe { &(*Subsystem::container_of(this)).data }
+ }
+}
+
+struct GroupOperationsVTable<Parent, Child>(PhantomData<(Parent, Child)>);
+
+impl<Parent, Child> GroupOperationsVTable<Parent, Child>
+where
+ Parent: GroupOperations<Child = Child>,
+ Child: 'static,
+{
+ /// # Safety
+ ///
+ /// `this` must be a valid pointer.
+ ///
+ /// If `this` does not represent the root group of a configfs subsystem,
+ /// `this` must be a pointer to a `bindings::config_group` embedded in a
+ /// `Group<Parent>`.
+ ///
+ /// Otherwise, `this` must be a pointer to a `bindings::config_group` that
+ /// is embedded in a `bindings::configfs_subsystem` that is embedded in a
+ /// `Subsystem<Parent>`.
+ ///
+ /// `name` must point to a null terminated string.
+ unsafe extern "C" fn make_group(
+ this: *mut bindings::config_group,
+ name: *const kernel::ffi::c_char,
+ ) -> *mut bindings::config_group {
+ // SAFETY: By function safety requirements of this function, this call
+ // is safe.
+ let parent_data = unsafe { get_group_data(this) };
+
+ let group_init = match Parent::make_group(
+ parent_data,
+ // SAFETY: By function safety requirements, name points to a null
+ // terminated string.
+ unsafe { CStr::from_char_ptr(name) },
+ ) {
+ Ok(init) => init,
+ Err(e) => return e.to_ptr(),
+ };
+
+ let child_group = <Arc<Group<Child>> as InPlaceInit<Group<Child>>>::try_pin_init(
+ group_init,
+ flags::GFP_KERNEL,
+ );
+
+ match child_group {
+ Ok(child_group) => {
+ let child_group_ptr = child_group.into_raw();
+ // SAFETY: We allocated the pointee of `child_ptr` above as a
+ // `Group<Child>`.
+ unsafe { Group::<Child>::group(child_group_ptr) }.cast_mut()
+ }
+ Err(e) => e.to_ptr(),
+ }
+ }
+
+ /// # Safety
+ ///
+ /// If `this` does not represent the root group of a configfs subsystem,
+ /// `this` must be a pointer to a `bindings::config_group` embedded in a
+ /// `Group<Parent>`.
+ ///
+ /// Otherwise, `this` must be a pointer to a `bindings::config_group` that
+ /// is embedded in a `bindings::configfs_subsystem` that is embedded in a
+ /// `Subsystem<Parent>`.
+ ///
+ /// `item` must point to a `bindings::config_item` within a
+ /// `bindings::config_group` within a `Group<Child>`.
+ unsafe extern "C" fn drop_item(
+ this: *mut bindings::config_group,
+ item: *mut bindings::config_item,
+ ) {
+ // SAFETY: By function safety requirements of this function, this call
+ // is safe.
+ let parent_data = unsafe { get_group_data(this) };
+
+ // SAFETY: By function safety requirements, `item` is embedded in a
+ // `config_group`.
+ let c_child_group_ptr = unsafe { container_of!(item, bindings::config_group, cg_item) };
+ // SAFETY: By function safety requirements, `c_child_group_ptr` is
+ // embedded within a `Group<Child>`.
+ let r_child_group_ptr = unsafe { Group::<Child>::container_of(c_child_group_ptr) };
+
+ if Parent::HAS_DROP_ITEM {
+ // SAFETY: We called `into_raw` to produce `r_child_group_ptr` in
+ // `make_group`.
+ let arc: Arc<Group<Child>> = unsafe { Arc::from_raw(r_child_group_ptr.cast_mut()) };
+
+ Parent::drop_item(parent_data, arc.as_arc_borrow());
+ arc.into_raw();
+ }
+
+ // SAFETY: By C API contract, we are required to drop a refcount on
+ // `item`.
+ unsafe { bindings::config_item_put(item) };
+ }
+
+ const VTABLE: bindings::configfs_group_operations = bindings::configfs_group_operations {
+ make_item: None,
+ make_group: Some(Self::make_group),
+ disconnect_notify: None,
+ drop_item: Some(Self::drop_item),
+ is_visible: None,
+ is_bin_visible: None,
+ };
+
+ const fn vtable_ptr() -> *const bindings::configfs_group_operations {
+ &Self::VTABLE as *const bindings::configfs_group_operations
+ }
+}
+
+struct ItemOperationsVTable<Container, Data>(PhantomData<(Container, Data)>);
+
+impl<Data> ItemOperationsVTable<Group<Data>, Data>
+where
+ Data: 'static,
+{
+ /// # Safety
+ ///
+ /// `this` must be a pointer to a `bindings::config_group` embedded in a
+ /// `Group<Parent>`.
+ ///
+ /// This function will destroy the pointee of `this`. The pointee of `this`
+ /// must not be accessed after the function returns.
+ unsafe extern "C" fn release(this: *mut bindings::config_item) {
+ // SAFETY: By function safety requirements, `this` is embedded in a
+ // `config_group`.
+ let c_group_ptr = unsafe { kernel::container_of!(this, bindings::config_group, cg_item) };
+ // SAFETY: By function safety requirements, `c_group_ptr` is
+ // embedded within a `Group<Data>`.
+ let r_group_ptr = unsafe { Group::<Data>::container_of(c_group_ptr) };
+
+ // SAFETY: We called `into_raw` on `r_group_ptr` in
+ // `make_group`.
+ let pin_self: Arc<Group<Data>> = unsafe { Arc::from_raw(r_group_ptr.cast_mut()) };
+ drop(pin_self);
+ }
+
+ const VTABLE: bindings::configfs_item_operations = bindings::configfs_item_operations {
+ release: Some(Self::release),
+ allow_link: None,
+ drop_link: None,
+ };
+
+ const fn vtable_ptr() -> *const bindings::configfs_item_operations {
+ &Self::VTABLE as *const bindings::configfs_item_operations
+ }
+}
+
+impl<Data> ItemOperationsVTable<Subsystem<Data>, Data> {
+ const VTABLE: bindings::configfs_item_operations = bindings::configfs_item_operations {
+ release: None,
+ allow_link: None,
+ drop_link: None,
+ };
+
+ const fn vtable_ptr() -> *const bindings::configfs_item_operations {
+ &Self::VTABLE as *const bindings::configfs_item_operations
+ }
+}
+
+/// Operations implemented by configfs groups that can create subgroups.
+///
+/// Implement this trait on structs that embed a [`Subsystem`] or a [`Group`].
+#[vtable]
+pub trait GroupOperations {
+ /// The child data object type.
+ ///
+ /// This group will create subgroups (subdirectories) backed by this kind of
+ /// object.
+ type Child: 'static;
+
+ /// Creates a new subgroup.
+ ///
+ /// The kernel will call this method in response to `mkdir(2)` in the
+ /// directory representing `this`.
+ ///
+ /// To accept the request to create a group, implementations should
+ /// return an initializer of a `Group<Self::Child>`. To prevent creation,
+ /// return a suitable error.
+ fn make_group(&self, name: &CStr) -> Result<impl PinInit<Group<Self::Child>, Error>>;
+
+ /// Prepares the group for removal from configfs.
+ ///
+ /// The kernel will call this method before the directory representing `_child` is removed from
+ /// configfs.
+ ///
+ /// Implementations can use this method to do house keeping before configfs drops its
+ /// reference to `Child`.
+ ///
+ /// NOTE: "drop" in the name of this function is not related to the Rust drop term. Rather, the
+ /// name is inherited from the callback name in the underlying C code.
+ fn drop_item(&self, _child: ArcBorrow<'_, Group<Self::Child>>) {
+ kernel::build_error!(kernel::error::VTABLE_DEFAULT_ERROR)
+ }
+}
+
+/// A configfs attribute.
+///
+/// An attribute appears as a file in configfs, inside a folder that represent
+/// the group that the attribute belongs to.
+#[repr(transparent)]
+pub struct Attribute<const ID: u64, O, Data> {
+ attribute: Opaque<bindings::configfs_attribute>,
+ _p: PhantomData<(O, Data)>,
+}
+
+// SAFETY: We do not provide any operations on `Attribute`.
+unsafe impl<const ID: u64, O, Data> Sync for Attribute<ID, O, Data> {}
+
+// SAFETY: Ownership of `Attribute` can safely be transferred to other threads.
+unsafe impl<const ID: u64, O, Data> Send for Attribute<ID, O, Data> {}
+
+impl<const ID: u64, O, Data> Attribute<ID, O, Data>
+where
+ O: AttributeOperations<ID, Data = Data>,
+{
+ /// # Safety
+ ///
+ /// `item` must be embedded in a `bindings::config_group`.
+ ///
+ /// If `item` does not represent the root group of a configfs subsystem,
+ /// the group must be embedded in a `Group<Data>`.
+ ///
+ /// Otherwise, the group must be a embedded in a
+ /// `bindings::configfs_subsystem` that is embedded in a `Subsystem<Data>`.
+ ///
+ /// `page` must point to a writable buffer of size at least [`PAGE_SIZE`].
+ unsafe extern "C" fn show(
+ item: *mut bindings::config_item,
+ page: *mut kernel::ffi::c_char,
+ ) -> isize {
+ let c_group: *mut bindings::config_group =
+ // SAFETY: By function safety requirements, `item` is embedded in a
+ // `config_group`.
+ unsafe { container_of!(item, bindings::config_group, cg_item) }.cast_mut();
+
+ // SAFETY: The function safety requirements for this function satisfy
+ // the conditions for this call.
+ let data: &Data = unsafe { get_group_data(c_group) };
+
+ // SAFETY: By function safety requirements, `page` is writable for `PAGE_SIZE`.
+ let ret = O::show(data, unsafe { &mut *(page as *mut [u8; PAGE_SIZE]) });
+
+ match ret {
+ Ok(size) => size as isize,
+ Err(err) => err.to_errno() as isize,
+ }
+ }
+
+ /// # Safety
+ ///
+ /// `item` must be embedded in a `bindings::config_group`.
+ ///
+ /// If `item` does not represent the root group of a configfs subsystem,
+ /// the group must be embedded in a `Group<Data>`.
+ ///
+ /// Otherwise, the group must be a embedded in a
+ /// `bindings::configfs_subsystem` that is embedded in a `Subsystem<Data>`.
+ ///
+ /// `page` must point to a readable buffer of size at least `size`.
+ unsafe extern "C" fn store(
+ item: *mut bindings::config_item,
+ page: *const kernel::ffi::c_char,
+ size: usize,
+ ) -> isize {
+ let c_group: *mut bindings::config_group =
+ // SAFETY: By function safety requirements, `item` is embedded in a
+ // `config_group`.
+ unsafe { container_of!(item, bindings::config_group, cg_item) }.cast_mut();
+
+ // SAFETY: The function safety requirements for this function satisfy
+ // the conditions for this call.
+ let data: &Data = unsafe { get_group_data(c_group) };
+
+ let ret = O::store(
+ data,
+ // SAFETY: By function safety requirements, `page` is readable
+ // for at least `size`.
+ unsafe { core::slice::from_raw_parts(page.cast(), size) },
+ );
+
+ match ret {
+ Ok(()) => size as isize,
+ Err(err) => err.to_errno() as isize,
+ }
+ }
+
+ /// Create a new attribute.
+ ///
+ /// The attribute will appear as a file with name given by `name`.
+ pub const fn new(name: &'static CStr) -> Self {
+ Self {
+ attribute: Opaque::new(bindings::configfs_attribute {
+ ca_name: name.as_char_ptr(),
+ ca_owner: core::ptr::null_mut(),
+ ca_mode: 0o660,
+ show: Some(Self::show),
+ store: if O::HAS_STORE {
+ Some(Self::store)
+ } else {
+ None
+ },
+ }),
+ _p: PhantomData,
+ }
+ }
+}
+
+/// Operations supported by an attribute.
+///
+/// Implement this trait on type and pass that type as generic parameter when
+/// creating an [`Attribute`]. The type carrying the implementation serve no
+/// purpose other than specifying the attribute operations.
+///
+/// This trait must be implemented on the `Data` type of for types that
+/// implement `HasGroup<Data>`. The trait must be implemented once for each
+/// attribute of the group. The constant type parameter `ID` maps the
+/// implementation to a specific `Attribute`. `ID` must be passed when declaring
+/// attributes via the [`kernel::configfs_attrs`] macro, to tie
+/// `AttributeOperations` implementations to concrete named attributes.
+#[vtable]
+pub trait AttributeOperations<const ID: u64 = 0> {
+ /// The type of the object that contains the field that is backing the
+ /// attribute for this operation.
+ type Data;
+
+ /// Renders the value of an attribute.
+ ///
+ /// This function is called by the kernel to read the value of an attribute.
+ ///
+ /// Implementations should write the rendering of the attribute to `page`
+ /// and return the number of bytes written.
+ fn show(data: &Self::Data, page: &mut [u8; PAGE_SIZE]) -> Result<usize>;
+
+ /// Stores the value of an attribute.
+ ///
+ /// This function is called by the kernel to update the value of an attribute.
+ ///
+ /// Implementations should parse the value from `page` and update internal
+ /// state to reflect the parsed value.
+ fn store(_data: &Self::Data, _page: &[u8]) -> Result {
+ kernel::build_error!(kernel::error::VTABLE_DEFAULT_ERROR)
+ }
+}
+
+/// A list of attributes.
+///
+/// This type is used to construct a new [`ItemType`]. It represents a list of
+/// [`Attribute`] that will appear in the directory representing a [`Group`].
+/// Users should not directly instantiate this type, rather they should use the
+/// [`kernel::configfs_attrs`] macro to declare a static set of attributes for a
+/// group.
+///
+/// # Note
+///
+/// Instances of this type are constructed statically at compile by the
+/// [`kernel::configfs_attrs`] macro.
+#[repr(transparent)]
+pub struct AttributeList<const N: usize, Data>(
+ /// Null terminated Array of pointers to [`Attribute`]. The type is [`c_void`]
+ /// to conform to the C API.
+ UnsafeCell<[*mut kernel::ffi::c_void; N]>,
+ PhantomData<Data>,
+);
+
+// SAFETY: Ownership of `AttributeList` can safely be transferred to other threads.
+unsafe impl<const N: usize, Data> Send for AttributeList<N, Data> {}
+
+// SAFETY: We do not provide any operations on `AttributeList` that need synchronization.
+unsafe impl<const N: usize, Data> Sync for AttributeList<N, Data> {}
+
+impl<const N: usize, Data> AttributeList<N, Data> {
+ /// # Safety
+ ///
+ /// This function must only be called by the [`kernel::configfs_attrs`]
+ /// macro.
+ #[doc(hidden)]
+ pub const unsafe fn new() -> Self {
+ Self(UnsafeCell::new([core::ptr::null_mut(); N]), PhantomData)
+ }
+
+ /// # Safety
+ ///
+ /// The caller must ensure that there are no other concurrent accesses to
+ /// `self`. That is, the caller has exclusive access to `self.`
+ #[doc(hidden)]
+ pub const unsafe fn add<const I: usize, const ID: u64, O>(
+ &'static self,
+ attribute: &'static Attribute<ID, O, Data>,
+ ) where
+ O: AttributeOperations<ID, Data = Data>,
+ {
+ // We need a space at the end of our list for a null terminator.
+ const { assert!(I < N - 1, "Invalid attribute index") };
+
+ // SAFETY: By function safety requirements, we have exclusive access to
+ // `self` and the reference created below will be exclusive.
+ unsafe {
+ (&mut *self.0.get())[I] = (attribute as *const Attribute<ID, O, Data>)
+ .cast_mut()
+ .cast()
+ };
+ }
+}
+
+/// A representation of the attributes that will appear in a [`Group`] or
+/// [`Subsystem`].
+///
+/// Users should not directly instantiate objects of this type. Rather, they
+/// should use the [`kernel::configfs_attrs`] macro to statically declare the
+/// shape of a [`Group`] or [`Subsystem`].
+#[pin_data]
+pub struct ItemType<Container, Data> {
+ #[pin]
+ item_type: Opaque<bindings::config_item_type>,
+ _p: PhantomData<(Container, Data)>,
+}
+
+// SAFETY: We do not provide any operations on `ItemType` that need synchronization.
+unsafe impl<Container, Data> Sync for ItemType<Container, Data> {}
+
+// SAFETY: Ownership of `ItemType` can safely be transferred to other threads.
+unsafe impl<Container, Data> Send for ItemType<Container, Data> {}
+
+macro_rules! impl_item_type {
+ ($tpe:ty) => {
+ impl<Data> ItemType<$tpe, Data> {
+ #[doc(hidden)]
+ pub const fn new_with_child_ctor<const N: usize, Child>(
+ owner: &'static ThisModule,
+ attributes: &'static AttributeList<N, Data>,
+ ) -> Self
+ where
+ Data: GroupOperations<Child = Child>,
+ Child: 'static,
+ {
+ Self {
+ item_type: Opaque::new(bindings::config_item_type {
+ ct_owner: owner.as_ptr(),
+ ct_group_ops: GroupOperationsVTable::<Data, Child>::vtable_ptr().cast_mut(),
+ ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(),
+ ct_attrs: (attributes as *const AttributeList<N, Data>)
+ .cast_mut()
+ .cast(),
+ ct_bin_attrs: core::ptr::null_mut(),
+ }),
+ _p: PhantomData,
+ }
+ }
+
+ #[doc(hidden)]
+ pub const fn new<const N: usize>(
+ owner: &'static ThisModule,
+ attributes: &'static AttributeList<N, Data>,
+ ) -> Self {
+ Self {
+ item_type: Opaque::new(bindings::config_item_type {
+ ct_owner: owner.as_ptr(),
+ ct_group_ops: core::ptr::null_mut(),
+ ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(),
+ ct_attrs: (attributes as *const AttributeList<N, Data>)
+ .cast_mut()
+ .cast(),
+ ct_bin_attrs: core::ptr::null_mut(),
+ }),
+ _p: PhantomData,
+ }
+ }
+ }
+ };
+}
+
+impl_item_type!(Subsystem<Data>);
+impl_item_type!(Group<Data>);
+
+impl<Container, Data> ItemType<Container, Data> {
+ fn as_ptr(&self) -> *const bindings::config_item_type {
+ self.item_type.get()
+ }
+}
+
+/// Define a list of configfs attributes statically.
+///
+/// Invoking the macro in the following manner:
+///
+/// ```ignore
+/// let item_type = configfs_attrs! {
+/// container: configfs::Subsystem<Configuration>,
+/// data: Configuration,
+/// child: Child,
+/// attributes: [
+/// message: 0,
+/// bar: 1,
+/// ],
+/// };
+/// ```
+///
+/// Expands the following output:
+///
+/// ```ignore
+/// let item_type = {
+/// static CONFIGURATION_MESSAGE_ATTR: kernel::configfs::Attribute<
+/// 0,
+/// Configuration,
+/// Configuration,
+/// > = unsafe {
+/// kernel::configfs::Attribute::new({
+/// const S: &str = "message\u{0}";
+/// const C: &kernel::str::CStr = match kernel::str::CStr::from_bytes_with_nul(
+/// S.as_bytes()
+/// ) {
+/// Ok(v) => v,
+/// Err(_) => {
+/// core::panicking::panic_fmt(core::const_format_args!(
+/// "string contains interior NUL"
+/// ));
+/// }
+/// };
+/// C
+/// })
+/// };
+///
+/// static CONFIGURATION_BAR_ATTR: kernel::configfs::Attribute<
+/// 1,
+/// Configuration,
+/// Configuration
+/// > = unsafe {
+/// kernel::configfs::Attribute::new({
+/// const S: &str = "bar\u{0}";
+/// const C: &kernel::str::CStr = match kernel::str::CStr::from_bytes_with_nul(
+/// S.as_bytes()
+/// ) {
+/// Ok(v) => v,
+/// Err(_) => {
+/// core::panicking::panic_fmt(core::const_format_args!(
+/// "string contains interior NUL"
+/// ));
+/// }
+/// };
+/// C
+/// })
+/// };
+///
+/// const N: usize = (1usize + (1usize + 0usize)) + 1usize;
+///
+/// static CONFIGURATION_ATTRS: kernel::configfs::AttributeList<N, Configuration> =
+/// unsafe { kernel::configfs::AttributeList::new() };
+///
+/// {
+/// const N: usize = 0usize;
+/// unsafe { CONFIGURATION_ATTRS.add::<N, 0, _>(&CONFIGURATION_MESSAGE_ATTR) };
+/// }
+///
+/// {
+/// const N: usize = (1usize + 0usize);
+/// unsafe { CONFIGURATION_ATTRS.add::<N, 1, _>(&CONFIGURATION_BAR_ATTR) };
+/// }
+///
+/// static CONFIGURATION_TPE:
+/// kernel::configfs::ItemType<configfs::Subsystem<Configuration> ,Configuration>
+/// = kernel::configfs::ItemType::<
+/// configfs::Subsystem<Configuration>,
+/// Configuration
+/// >::new_with_child_ctor::<N,Child>(
+/// &THIS_MODULE,
+/// &CONFIGURATION_ATTRS
+/// );
+///
+/// &CONFIGURATION_TPE
+/// }
+/// ```
+#[macro_export]
+macro_rules! configfs_attrs {
+ (
+ container: $container:ty,
+ data: $data:ty,
+ attributes: [
+ $($name:ident: $attr:literal),* $(,)?
+ ] $(,)?
+ ) => {
+ $crate::configfs_attrs!(
+ count:
+ @container($container),
+ @data($data),
+ @child(),
+ @no_child(x),
+ @attrs($($name $attr)*),
+ @eat($($name $attr,)*),
+ @assign(),
+ @cnt(0usize),
+ )
+ };
+ (
+ container: $container:ty,
+ data: $data:ty,
+ child: $child:ty,
+ attributes: [
+ $($name:ident: $attr:literal),* $(,)?
+ ] $(,)?
+ ) => {
+ $crate::configfs_attrs!(
+ count:
+ @container($container),
+ @data($data),
+ @child($child),
+ @no_child(),
+ @attrs($($name $attr)*),
+ @eat($($name $attr,)*),
+ @assign(),
+ @cnt(0usize),
+ )
+ };
+ (count:
+ @container($container:ty),
+ @data($data:ty),
+ @child($($child:ty)?),
+ @no_child($($no_child:ident)?),
+ @attrs($($aname:ident $aattr:literal)*),
+ @eat($name:ident $attr:literal, $($rname:ident $rattr:literal,)*),
+ @assign($($assign:block)*),
+ @cnt($cnt:expr),
+ ) => {
+ $crate::configfs_attrs!(
+ count:
+ @container($container),
+ @data($data),
+ @child($($child)?),
+ @no_child($($no_child)?),
+ @attrs($($aname $aattr)*),
+ @eat($($rname $rattr,)*),
+ @assign($($assign)* {
+ const N: usize = $cnt;
+ // The following macro text expands to a call to `Attribute::add`.
+
+ // SAFETY: By design of this macro, the name of the variable we
+ // invoke the `add` method on below, is not visible outside of
+ // the macro expansion. The macro does not operate concurrently
+ // on this variable, and thus we have exclusive access to the
+ // variable.
+ unsafe {
+ $crate::macros::paste!(
+ [< $data:upper _ATTRS >]
+ .add::<N, $attr, _>(&[< $data:upper _ $name:upper _ATTR >])
+ )
+ };
+ }),
+ @cnt(1usize + $cnt),
+ )
+ };
+ (count:
+ @container($container:ty),
+ @data($data:ty),
+ @child($($child:ty)?),
+ @no_child($($no_child:ident)?),
+ @attrs($($aname:ident $aattr:literal)*),
+ @eat(),
+ @assign($($assign:block)*),
+ @cnt($cnt:expr),
+ ) =>
+ {
+ $crate::configfs_attrs!(
+ final:
+ @container($container),
+ @data($data),
+ @child($($child)?),
+ @no_child($($no_child)?),
+ @attrs($($aname $aattr)*),
+ @assign($($assign)*),
+ @cnt($cnt),
+ )
+ };
+ (final:
+ @container($container:ty),
+ @data($data:ty),
+ @child($($child:ty)?),
+ @no_child($($no_child:ident)?),
+ @attrs($($name:ident $attr:literal)*),
+ @assign($($assign:block)*),
+ @cnt($cnt:expr),
+ ) =>
+ {
+ $crate::macros::paste!{
+ {
+ $(
+ // SAFETY: We are expanding `configfs_attrs`.
+ static [< $data:upper _ $name:upper _ATTR >]:
+ $crate::configfs::Attribute<$attr, $data, $data> =
+ unsafe {
+ $crate::configfs::Attribute::new(c_str!(::core::stringify!($name)))
+ };
+ )*
+
+
+ // We need space for a null terminator.
+ const N: usize = $cnt + 1usize;
+
+ // SAFETY: We are expanding `configfs_attrs`.
+ static [< $data:upper _ATTRS >]:
+ $crate::configfs::AttributeList<N, $data> =
+ unsafe { $crate::configfs::AttributeList::new() };
+
+ $($assign)*
+
+ $(
+ const [<$no_child:upper>]: bool = true;
+
+ static [< $data:upper _TPE >] : $crate::configfs::ItemType<$container, $data> =
+ $crate::configfs::ItemType::<$container, $data>::new::<N>(
+ &THIS_MODULE, &[<$ data:upper _ATTRS >]
+ );
+ )?
+
+ $(
+ static [< $data:upper _TPE >]:
+ $crate::configfs::ItemType<$container, $data> =
+ $crate::configfs::ItemType::<$container, $data>::
+ new_with_child_ctor::<N, $child>(
+ &THIS_MODULE, &[<$ data:upper _ATTRS >]
+ );
+ )?
+
+ & [< $data:upper _TPE >]
+ }
+ }
+ };
+
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index de07aadd1ff5fe46fd89517e234b97a6590c8e93..bcbf5026449d80d3b1493c782d3c1c63103391e1 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -42,6 +42,8 @@
pub mod block;
#[doc(hidden)]
pub mod build_assert;
+#[cfg(CONFIG_CONFIGFS_FS)]
+pub mod configfs;
pub mod cred;
pub mod device;
pub mod device_id;
--
2.47.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v8 2/3] rust: configfs: add a sample demonstrating configfs usage
2025-05-08 8:52 [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 1/3] rust: configfs: introduce rust support for configfs Andreas Hindborg
@ 2025-05-08 8:52 ` Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 3/3] MAINTAINERS: add configfs Rust abstractions Andreas Hindborg
2025-05-12 10:43 ` [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
3 siblings, 0 replies; 5+ messages in thread
From: Andreas Hindborg @ 2025-05-08 8:52 UTC (permalink / raw)
To: Danilo Krummrich, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Alice Ryhl, Trevor Gross,
Joel Becker, Peter Zijlstra, Ingo Molnar, Will Deacon,
Waiman Long, Fiona Behrens, Charalampos Mitrodimas,
Daniel Almeida, Breno Leitao
Cc: rust-for-linux, linux-kernel, Andreas Hindborg
Add a sample to the samples folder, demonstrating the intended use of the
Rust configfs API.
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
samples/rust/Kconfig | 11 +++
samples/rust/Makefile | 1 +
samples/rust/rust_configfs.rs | 192 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 204 insertions(+)
diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index cad52b7120b5143e85d737234be4ff27d2c7f99f..be491ad9b3af1b21d5c1d6000ef6c5488f9c5e91 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -10,6 +10,17 @@ menuconfig SAMPLES_RUST
if SAMPLES_RUST
+config SAMPLE_RUST_CONFIGFS
+ tristate "Configfs sample"
+ depends on CONFIGFS_FS
+ help
+ This option builds the Rust configfs sample.
+
+ To compile this as a module, choose M here:
+ the module will be called rust_configfs.
+
+ If unsure, say N.
+
config SAMPLE_RUST_MINIMAL
tristate "Minimal"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index c6a2479f7d9cf3a8695fa08b33b71d0df077eb59..b3c9178d654afed5c9553b1b6fa91ae8736c316e 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_SAMPLE_RUST_DMA) += rust_dma.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_PCI) += rust_driver_pci.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM) += rust_driver_platform.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_FAUX) += rust_driver_faux.o
+obj-$(CONFIG_SAMPLE_RUST_CONFIGFS) += rust_configfs.o
rust_print-y := rust_print_main.o rust_print_events.o
diff --git a/samples/rust/rust_configfs.rs b/samples/rust/rust_configfs.rs
new file mode 100644
index 0000000000000000000000000000000000000000..60ddbe62cda31465f799f1c15f92bdc88f855830
--- /dev/null
+++ b/samples/rust/rust_configfs.rs
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust configfs sample.
+
+use kernel::alloc::flags;
+use kernel::c_str;
+use kernel::configfs;
+use kernel::configfs_attrs;
+use kernel::new_mutex;
+use kernel::page::PAGE_SIZE;
+use kernel::prelude::*;
+use kernel::sync::Mutex;
+
+module! {
+ type: RustConfigfs,
+ name: "rust_configfs",
+ author: "Rust for Linux Contributors",
+ description: "Rust configfs sample",
+ license: "GPL",
+}
+
+#[pin_data]
+struct RustConfigfs {
+ #[pin]
+ config: configfs::Subsystem<Configuration>,
+}
+
+#[pin_data]
+struct Configuration {
+ message: &'static CStr,
+ #[pin]
+ bar: Mutex<(KBox<[u8; PAGE_SIZE]>, usize)>,
+}
+
+impl Configuration {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ message: c_str!("Hello World\n"),
+ bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)),
+ })
+ }
+}
+
+impl kernel::InPlaceModule for RustConfigfs {
+ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
+ pr_info!("Rust configfs sample (init)\n");
+
+ // Define a subsystem with the data type `Configuration`, two
+ // attributes, `message` and `bar` and child group type `Child`. `mkdir`
+ // in the directory representing this subsystem will create directories
+ // backed by the `Child` type.
+ let item_type = configfs_attrs! {
+ container: configfs::Subsystem<Configuration>,
+ data: Configuration,
+ child: Child,
+ attributes: [
+ message: 0,
+ bar: 1,
+ ],
+ };
+
+ try_pin_init!(Self {
+ config <- configfs::Subsystem::new(
+ c_str!("rust_configfs"), item_type, Configuration::new()
+ ),
+ })
+ }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Configuration {
+ type Child = Child;
+
+ fn make_group(&self, name: &CStr) -> Result<impl PinInit<configfs::Group<Child>, Error>> {
+ // Define a group with data type `Child`, one attribute `baz` and child
+ // group type `GrandChild`. `mkdir` in the directory representing this
+ // group will create directories backed by the `GrandChild` type.
+ let tpe = configfs_attrs! {
+ container: configfs::Group<Child>,
+ data: Child,
+ child: GrandChild,
+ attributes: [
+ baz: 0,
+ ],
+ };
+
+ Ok(configfs::Group::new(name.try_into()?, tpe, Child::new()))
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for Configuration {
+ type Data = Configuration;
+
+ fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show message\n");
+ let data = container.message;
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<1> for Configuration {
+ type Data = Configuration;
+
+ fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show bar\n");
+ let guard = container.bar.lock();
+ let data = guard.0.as_slice();
+ let len = guard.1;
+ page[0..len].copy_from_slice(&data[0..len]);
+ Ok(len)
+ }
+
+ fn store(container: &Configuration, page: &[u8]) -> Result {
+ pr_info!("Store bar\n");
+ let mut guard = container.bar.lock();
+ guard.0[0..page.len()].copy_from_slice(page);
+ guard.1 = page.len();
+ Ok(())
+ }
+}
+
+// `pin_data` cannot handle structs without braces.
+#[pin_data]
+struct Child {}
+
+impl Child {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {})
+ }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Child {
+ type Child = GrandChild;
+
+ fn make_group(&self, name: &CStr) -> Result<impl PinInit<configfs::Group<GrandChild>, Error>> {
+ // Define a group with data type `GrandChild`, one attribute `gc`. As no
+ // child type is specified, it will not be possible to create subgroups
+ // in this group, and `mkdir`in the directory representing this group
+ // will return an error.
+ let tpe = configfs_attrs! {
+ container: configfs::Group<GrandChild>,
+ data: GrandChild,
+ attributes: [
+ gc: 0,
+ ],
+ };
+
+ Ok(configfs::Group::new(
+ name.try_into()?,
+ tpe,
+ GrandChild::new(),
+ ))
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for Child {
+ type Data = Child;
+
+ fn show(_container: &Child, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show baz\n");
+ let data = c"Hello Baz\n".to_bytes();
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}
+
+// `pin_data` cannot handle structs without braces.
+#[pin_data]
+struct GrandChild {}
+
+impl GrandChild {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {})
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for GrandChild {
+ type Data = GrandChild;
+
+ fn show(_container: &GrandChild, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show grand child\n");
+ let data = c"Hello GC\n".to_bytes();
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}
--
2.47.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v8 3/3] MAINTAINERS: add configfs Rust abstractions
2025-05-08 8:52 [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 1/3] rust: configfs: introduce rust support for configfs Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 2/3] rust: configfs: add a sample demonstrating configfs usage Andreas Hindborg
@ 2025-05-08 8:52 ` Andreas Hindborg
2025-05-12 10:43 ` [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
3 siblings, 0 replies; 5+ messages in thread
From: Andreas Hindborg @ 2025-05-08 8:52 UTC (permalink / raw)
To: Danilo Krummrich, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Alice Ryhl, Trevor Gross,
Joel Becker, Peter Zijlstra, Ingo Molnar, Will Deacon,
Waiman Long, Fiona Behrens, Charalampos Mitrodimas,
Daniel Almeida, Breno Leitao
Cc: rust-for-linux, linux-kernel, Andreas Hindborg
Add rust files to configfs MAINTAINERS entry.
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
MAINTAINERS | 2 ++
1 file changed, 2 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 3cbf9ac0d83f619ef873833b26a3aa3f29ff4161..5ccf04e1eb1fd02e7906e94cb5b0acd49e334d98 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5982,7 +5982,9 @@ S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/a.hindborg/linux.git configfs-next
F: fs/configfs/
F: include/linux/configfs.h
+F: rust/kernel/configfs.rs
F: samples/configfs/
+F: samples/rust/rust_configfs.rs
CONGATEC BOARD CONTROLLER MFD DRIVER
M: Thomas Richard <thomas.richard@bootlin.com>
--
2.47.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v8 0/3] rust: configfs abstractions
2025-05-08 8:52 [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
` (2 preceding siblings ...)
2025-05-08 8:52 ` [PATCH v8 3/3] MAINTAINERS: add configfs Rust abstractions Andreas Hindborg
@ 2025-05-12 10:43 ` Andreas Hindborg
3 siblings, 0 replies; 5+ messages in thread
From: Andreas Hindborg @ 2025-05-12 10:43 UTC (permalink / raw)
To: Danilo Krummrich, Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Alice Ryhl, Trevor Gross,
Joel Becker, Peter Zijlstra, Ingo Molnar, Will Deacon,
Waiman Long, Fiona Behrens, Charalampos Mitrodimas,
Daniel Almeida, Breno Leitao, Andreas Hindborg
Cc: rust-for-linux, linux-kernel
On Thu, 08 May 2025 10:52:08 +0200, Andreas Hindborg wrote:
> Add a safe Rust API that allows Rust modules to interface the `configfs`
> machinery.
>
> Add an example for the samples folder to demonstrate usage of the API.
>
> Add a maintainer entry for the Rust configfs abstractions in the last patch, to
> make it absolutely clear that I will commit to maintain these abstractions, if
> required.
>
> [...]
Applied, thanks!
[1/3] rust: configfs: introduce rust support for configfs
commit: 446cafc295bfc0e89da94a482fe8290bd8b429fb
[2/3] rust: configfs: add a sample demonstrating configfs usage
commit: 1bfb105051566ec5cc7c4f693362420b37a68781
[3/3] MAINTAINERS: add configfs Rust abstractions
commit: c6b1908224593db76f77b904894cd51933559ae9
Best regards,
--
Andreas Hindborg <a.hindborg@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2025-05-12 10:44 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2025-05-08 8:52 [PATCH v8 0/3] rust: configfs abstractions Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 1/3] rust: configfs: introduce rust support for configfs Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 2/3] rust: configfs: add a sample demonstrating configfs usage Andreas Hindborg
2025-05-08 8:52 ` [PATCH v8 3/3] MAINTAINERS: add configfs Rust abstractions Andreas Hindborg
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