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 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 (4):
      rust: sync: change `<Arc<T> as ForeignOwnable>::PointedTo` to `T`
      rust: configfs: introduce rust support for configfs
      rust: configfs: add a sample demonstrating configfs usage
      MAINTAINERS: add entry for configfs Rust abstractions

 MAINTAINERS                     |    7 +
 rust/bindings/bindings_helper.h |    1 +
 rust/helpers/mutex.c            |    5 +
 rust/kernel/configfs.rs         | 1054 +++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |    2 +
 rust/kernel/sync/arc.rs         |   21 +-
 samples/rust/Kconfig            |   11 +
 samples/rust/Makefile           |    1 +
 samples/rust/rust_configfs.rs   |  192 +++++++
 9 files changed, 1289 insertions(+), 5 deletions(-)
---
base-commit: 379487e17ca406b47392e7ab6cf35d1c3bacb371
change-id: 20250131-configfs-b888cd82d84a
prerequisite-patch-id: 03c1bff48fd24e83d1383e98f8668300e665ebae

Best regards,
-- 
Andreas Hindborg <a.hindborg@kernel.org>

Hi Joel,

"Andreas Hindborg" <a.hindborg@kernel.org> writes:

> 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>

Since you are not responding to my emails, I must assume that either you
did not see them, you are too busy to respond, or you are ignoring them.

Please note that if the lack of response is due to you being busy, my
offer to help out with C configfs still stands [1].

If I do not hear anything back from you, I will have to ask for these
patches to be routed through the rust subsystem tree instead of the
configfs tree.


Best regards,
Andreas Hindborg



[1] https://lore.kernel.org/all/87cyf3p6sj.fsf@kernel.org/