Re: [PATCH 5/6] sched_ext: Move scx_tasks_lock handling into scx_task_iter helpers

[David Vernet <void@manifault.com>]

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On Wed, Oct 09, 2024 at 11:41:01AM -1000, Tejun Heo wrote:
> Iterating with scx_task_iter involves scx_tasks_lock and optionally the rq
> lock of the task being iterated. Both locks can be released during iteration
> and the iteration can be continued after re-grabbing scx_tasks_lock.
> Currently, all lock handling is pushed to the caller which is a bit
> cumbersome and makes it difficult to add lock-aware behaviors. Make the
> scx_task_iter helpers handle scx_tasks_lock.
> 
> - scx_task_iter_init/scx_taks_iter_exit() now grabs and releases
>   scx_task_lock, respectively. Renamed to
>   scx_task_iter_start/scx_task_iter_stop() to more clearly indicate that
>   there are non-trivial side-effects.
> 
> - Add __ prefix to scx_task_iter_rq_unlock() to indicate that the function
>   is internal.
> 
> - Add scx_task_iter_unlock/relock(). The former drops both rq lock (if held)
>   and scx_tasks_lock and the latter re-locks only scx_tasks_lock.
> 
> This doesn't cause behavior changes and will be used to implement stall
> avoidance.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>

Thanks for the nice little cleanup.

Acked-by: David Vernet <void@manifault.com>

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