Re: [PATCH v6 0/7] rust: add `ww_mutex` support

Lyude Paul
2025-10-16T19:47:15Z

Hi! One thing I realized I forgot to ask the last time I reviewed this: one of
the things that seems to be missing is the ability to use this API with locks
and lock-acquisition mechanisms that already exist on the C side of the
kernel.

I think the simplest equivalent to this I can point to is how we have:

* Mutex::from_raw() (but only when the type protected by the mutex is () )
* Guard::from_raw()

For ww mutexes we should have both of these as well, and also ::from_raw() for
WwAcquireCtx. This being said - as far as I can tell, it doesn't look like it
would be a big change for this series at all.

Also - thank you for the work so far :)

On Wed, 2025-09-03 at 16:13 +0300, Onur Özkan wrote:
> Changes made in v6:
> - Added `unpinned_new` constructor for `WwClass` and updated global macros.
> - Changed all tests (and docs) to use Arc/KBox instead of `stack_pin_init`
> for `WwMutex` and `WwAcquireCtx`.
> - Added `LockKind` and `lock_common` helper to unify locking logic.
> - Added context-based and context-free locking functions for `WwMutex`.
> - Added `ww_mutex/exec` module, a high-level API with auto `EDEADLK`
> handling mechanism.
>
> Onur Özkan (7):
> rust: add C wrappers for ww_mutex inline functions
> rust: implement `WwClass` for ww_mutex support
> rust: implement `WwMutex`, `WwAcquireCtx` and `WwMutexGuard`
> add KUnit coverage on Rust ww_mutex implementation
> rust: ww_mutex: add context-free locking functions
> rust: ww_mutex/exec: add high-level API
> add KUnit coverage on ww_mutex/exec implementation
>
> rust/helpers/helpers.c | 1 +
> rust/helpers/ww_mutex.c | 39 ++
> rust/kernel/error.rs | 1 +
> rust/kernel/sync/lock.rs | 1 +
> rust/kernel/sync/lock/ww_mutex.rs | 634 +++++++++++++++++++++++++
> rust/kernel/sync/lock/ww_mutex/exec.rs | 324 +++++++++++++
> 6 files changed, 1000 insertions(+)
> create mode 100644 rust/helpers/ww_mutex.c
> create mode 100644 rust/kernel/sync/lock/ww_mutex.rs
> create mode 100644 rust/kernel/sync/lock/ww_mutex/exec.rs
>
> --
> 2.50.0

--
Cheers, Lyude Paul (she/her) Senior Software Engineer at Red Hat Ignore all
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