Re: [PATCH 2/2] rust: kcsan: add KUnit test for data race detection

[Marco Elver]

On Tue, 13 Oct 2026 at 12:32, Miguel Ojeda
<miguel.ojeda.sandonis@xxxxxxxxx> wrote:
>
> On Tue, Oct 13, 2026 at 12:10 PM Marco Elver <elver@xxxxxxxxxx> wrote:
> >
> > Looks like it, and we need this patch to use system_dfl_wq:
> >
> >
> > From: Marco Elver <elver@xxxxxxxxxx>
> > Date: Tue, 13 Oct 2026 10:05:52 +0000
> > Subject: [PATCH] rust: workqueue: add system_dfl()
> >
> > The C kernel deprecated system_unbound_wq in favor of system_dfl_wq
> > (commit 64d8eae3f895 ("workqueue: Add warnings and fallback if
> > system_{unbound}_wq is used")).
> >
> > Add `system_dfl()` to provide a safe wrapper around `system_dfl_wq`.
> >
> > Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> > ---
> >  rust/kernel/workqueue.rs | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
> > index 7e253b6f299c..e46d3acf903d 100644
> > --- a/rust/kernel/workqueue.rs
> > +++ b/rust/kernel/workqueue.rs
> > @@ -1063,6 +1063,16 @@ pub fn system_unbound() -> &'static Queue {
> >      unsafe { Queue::from_raw(bindings::system_unbound_wq) }
> >  }
> >
> > +/// Returns the system default work queue (`system_dfl_wq`).
> > +///
> > +/// Workers are not bound to any specific CPU, not concurrency managed, and all queued work items
> > +/// are executed immediately as long as `max_active` limit is not reached and resources are
> > +/// available.
> > +pub fn system_dfl() -> &'static Queue {
> > +    // SAFETY: `system_dfl_wq` is a C global, always available.
> > +    unsafe { Queue::from_raw(bindings::system_dfl_wq) }
> > +}
> > +
> >  /// Returns the system freezable work queue (`system_freezable_wq`).
> >  ///
> >  /// It is equivalent to the one returned by [`system`] except that it's freezable.
> > --
> > 2.56.0.385.gd3acb90ef8-goog
>
> This is:
>
>   https://lore.kernel.org/rust-for-linux/20260807165252.3849875-2-dakr@xxxxxxxxxx/
>
> i.e. we have had a warning like that in one of our current tests for a
> while, it would be nice to clean it up:
>
>     workqueue: work func
>     _RNvXs8_NtCs5lxGbhOOw2k_6kernel9workqueueINtNtNtB7_4sync3arc3ArcNtNtNtNtBH_4lock8spinlock5tests4TestEINtB5_15WorkItemPointerKy0_E3runB7_
>     enqueued on deprecated workqueue. Use system_{percpu|dfl}_wq instead.
>
> Cc'ing workqueue: Tejun and Lai.

But I take it that the series above is not yet merged?

So I'll keep the previous interface for my test to avoid introducing
conflicting patches.