[PATCH v4 0/3] Creation of workqueues in Rust

[PATCH v4 0/3] Creation of workqueues in Rust

[Alice Ryhl]

GPU drivers often need to create their own workqueues for various
reasons. Add the ability to do so.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Changes in v4:
- Add link to delayed work fix.
- Redo workqueue creation to prevent invalid configurations.
- Introduce a directory as workqueue.rs was getting really large.
- Link to v3: https://lore.kernel.org/r/20260227-create-workqueue-v3-0-87de133f7849@google.com

Changes in v3:
- Switch to builder pattern.
- Drop BH workqueues for now.
- Mark delayed wq change as fix.
- Link to v2: https://lore.kernel.org/r/20251113-create-workqueue-v2-0-8b45277119bc@google.com

Changes in v2:
- Redo how flagging works.
- Restrict delayed work to not be usable on custom workqueues.
- Link to v1: https://lore.kernel.org/r/20250411-create-workqueue-v1-1-f7dbe7f1e05f@google.com

---
Alice Ryhl (3):
      rust: workqueue: restrict delayed work to global wqs
      rust: workqueue: create workqueue subdirectory
      rust: workqueue: add creation of workqueues

 MAINTAINERS                                    |   1 +
 rust/helpers/workqueue.c                       |   7 +
 rust/kernel/workqueue/builder.rs               | 380 +++++++++++++++++++++++++
 rust/kernel/{workqueue.rs => workqueue/mod.rs} |  53 +++-
 4 files changed, 437 insertions(+), 4 deletions(-)
---
base-commit: df9c51269a5e2a6fbca2884a756a4011a5e78748
change-id: 20250411-create-workqueue-d053158c7a4b

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>

[PATCH v4 1/3] rust: workqueue: restrict delayed work to global wqs

[Alice Ryhl]

When a workqueue is shut down, delayed work that is pending but not
scheduled does not get properly cleaned up, so it's not safe to use
`enqueue_delayed` on a workqueue that might be destroyed. To fix this,
restricted `enqueue_delayed` to static queues.

This may be fixed in the future by an approach along the lines of [1].

Cc: stable@vger.kernel.org
Fixes: 7c098cd5eaae ("workqueue: rust: add delayed work items")
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20250423-destroy-workqueue-flush-v1-1-3d74820780a5@google.com [1]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 rust/kernel/workqueue.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 706e833e9702..1acd113c04ee 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -296,8 +296,15 @@ pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput
     ///
     /// This may fail if the work item is already enqueued in a workqueue.
     ///
+    /// This is only valid for global workqueues (with static lifetimes) because those are the only
+    /// ones that outlive all possible delayed work items.
+    ///
     /// The work item will be submitted using `WORK_CPU_UNBOUND`.
-    pub fn enqueue_delayed<W, const ID: u64>(&self, w: W, delay: Jiffies) -> W::EnqueueOutput
+    pub fn enqueue_delayed<W, const ID: u64>(
+        &'static self,
+        w: W,
+        delay: Jiffies,
+    ) -> W::EnqueueOutput
     where
         W: RawDelayedWorkItem<ID> + Send + 'static,
     {

-- 
2.53.0.473.g4a7958ca14-goog

Re: [PATCH v4 1/3] rust: workqueue: restrict delayed work to global wqs

[Andreas Hindborg]

"Alice Ryhl" <aliceryhl@google.com> writes:

> When a workqueue is shut down, delayed work that is pending but not
> scheduled does not get properly cleaned up, so it's not safe to use
> `enqueue_delayed` on a workqueue that might be destroyed. To fix this,
> restricted `enqueue_delayed` to static queues.
>
> This may be fixed in the future by an approach along the lines of [1].
>
> Cc: stable@vger.kernel.org
> Fixes: 7c098cd5eaae ("workqueue: rust: add delayed work items")
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Reviewed-by: Danilo Krummrich <dakr@kernel.org>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Link: https://lore.kernel.org/r/20250423-destroy-workqueue-flush-v1-1-3d74820780a5@google.com [1]
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>



Best regards,
Andreas Hindborg