[PATCH v4 0/3] rust: Add pr_*_once macros

[Jens Korinth via B4 Relay]

Add Rust version of pr_[emerg|alert|crit|err|warn|notic|info]_once
functions, which print a message only once.

Introduces a `OnceLite` abstraction similar to Rust's
[`std::sync::Once`](https://doc.rust-lang.org/std/sync/struct.Once.html)
but using the non-blocking mechanism from the kernel's `DO_ONCE_LITE`
macro, which is used to define the `do_once_lite` Rust macro.

First use case are an implementation of `pr_*_once` message macros to
print a message only once.

v4:
- Move `do_once_lite` macro implementation to `OnceLite` abstraction
- Use `OnceLite` in `do_once_lite`
- More documentation, examples
v3: https://lore.kernel.org/rust-for-linux/20241109-pr_once_macros-v3-0-6beb24e0cac8@xxxxxxx/
- Fix rustdoc error, formatting issues
- Fix missing Signed-off-by
v2: https://lore.kernel.org/r/20241107-pr_once_macros-v2-0-dc0317ff301e@xxxxxxx
- Split patch into do_once_lite part and pr_*_once macros
- Add macro rule for call without condition => renamed to do_once_lite
- Used condition-less call in pr_*_once macros
- Added examples
- Removed TODO in kernel/error.rs using pr_warn_once
v1: https://lore.kernel.org/rust-for-linux/20241106.083113.356536037967804464.fujita.tomonori@xxxxxxxxx/

Co-developed-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
Co-developed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Signed-off-by: Jens Korinth <jens.korinth@xxxxxxx>
---
FUJITA Tomonori (1):
      rust: print: Add pr_*_once macros

Jens Korinth (2):
      rust: Add `OnceLite` for executing code once
      rust: error: Replace pr_warn by pr_warn_once

 rust/kernel/error.rs     |   3 +-
 rust/kernel/lib.rs       |   1 +
 rust/kernel/once_lite.rs | 127 +++++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/print.rs     | 126 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 255 insertions(+), 2 deletions(-)
---
base-commit: b2603f8ac8217bc59f5c7f248ac248423b9b99cb
change-id: 20241107-pr_once_macros-6438e6f5b923

Best regards,
-- 
Jens Korinth <jens.korinth@xxxxxxx>