Re: [PATCH] sched_ext: Fix spurious WARN on stale ops_state in ops_dequeue()

[Samuele Mariotti <smariotti@disroot.org>]

Hello Andrea,

On 14/05/2026 22:08, Andrea Righi wrote:
...
>The code looks good to me, I'd elaborate more on the comment to make it clear
>that the retry loop is guaranteed to terminate (not a deadlock).
>
>How about this (or something along these lines)?
>
> /*
>  * A queued task must be in BPF scheduler's custody. If
>  * SCX_TASK_IN_CUSTODY is clear, finish_dispatch() on another
>  * CPU has already passed call_task_dequeue() (which clears the
>  * flag), but has not yet written SCX_OPSS_NONE. That final
>  * store does not require this rq's lock, so retrying with
>  * cpu_relax() is bounded: we'll observe NONE (or DISPATCHING,
>  * handled by the fallthrough) on a subsequent iteration.
>  */
>
>Thanks,
>-Andrea

Agreed, the comment covers all the relevant aspects and explains the if
condition clearly. I would go with it.


Thanks,
Samuele