On 23 Dec 2022 15:51:52 +0900 Daisuke Matsuda <matsuda-dais...@fujitsu.com>
> @@ -137,15 +153,27 @@ void rxe_sched_task(struct rxe_task *task)
> if (task->destroyed)
> return;
>
> - tasklet_schedule(&task->tasklet);
> + /*
> + * busy-loop while qp reset is in progress.
> + * This may be called from softirq context and thus cannot sleep.
> + */
> + while (atomic_read(&task->suspended))
> + cpu_relax();
> +
> + queue_work(task->workq, &task->work);
> }
This busy wait particularly in softirq barely makes sense given the
flush_workqueue() below.
>
> void rxe_disable_task(struct rxe_task *task)
> {
> - tasklet_disable(&task->tasklet);
> + /* Alternative to tasklet_disable() */
> + atomic_inc(&task->suspended);
> + smp_mb__after_atomic();
> + flush_workqueue(task->workq);
> }
>
> void rxe_enable_task(struct rxe_task *task)
> {
> - tasklet_enable(&task->tasklet);
> + /* Alternative to tasklet_enable() */
> + smp_mb__before_atomic();
> + atomic_dec(&task->suspended);
> }
Feel free to add one-line comment for why smp_mb is needed in both
cases.
