[PATCH v2 0/5] rust: sync: add WaitQueue infrastructure

[Danilo Krummrich <dakr@kernel.org>]

Add a WaitQueue abstraction wrapping struct wait_queue_head, providing
wait_event()-style methods that take a condition closure directly.

This is needed for a (subsequent) DRM patch series to wait for in-flight file
close operations during driver unbind. The Tyr driver also needs it for "CSF
firmware responses and other GPU-driven events" [1].

Convert CondVar (and PollCondVar) to use WaitQueue internally, removing
duplicate code using WaitQueue as the base primitive and add
wait_interruptible_freezable_nonexclusive() for subsequent binder usage.

Changes in v2:
- Drop the already merged workqueue patch.
- Make as_raw() public.
- Split error types and use bindings constants for direct C calls.
- Avoid condition rechecks after success.
- Check the condition before preparing a waiter.
- Add non-exclusive wait support, including a CondVar method for subsequent
  Binder conversion.
- Handle zero and expired timeouts before interruption; extend KUnit coverage.

[1] https://lore.kernel.org/dri-devel/20260721151423.444175-2-laura.nao@collabora.com/

Danilo Krummrich (5):
  rust: task: add safe schedule_timeout() wrapper
  rust: sync: add WaitQueue infrastructure
  rust: sync: convert CondVar and PollCondVar to use WaitQueue
  rust: sync: condvar: use task::schedule_timeout()
  rust: sync: condvar: add non-exclusive freezable waiting

 rust/kernel/sync.rs         |   8 +
 rust/kernel/sync/condvar.rs | 134 ++++-----
 rust/kernel/sync/poll.rs    |  19 +-
 rust/kernel/sync/wait.rs    | 524 ++++++++++++++++++++++++++++++++++++
 rust/kernel/task.rs         |  16 ++
 5 files changed, 612 insertions(+), 89 deletions(-)
 create mode 100644 rust/kernel/sync/wait.rs


base-commit: 41871f4ddf710339863f957bcfcab5094c234771
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2.56.0