On Mon, Apr 18, 2022 at 3:12 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>
> Hmm yes. But doesn't preemption imply a full barrier? As long as we
> assign the plug at the end, we should be fine. And just now looking that
> up, there's even already a comment to that effect in blk_start_plug().
> So barring any weirdness with that, maybe that's the solution.
My worry is more about the code that adds new cb_list entries to the
plug, racing with then some random preemption event that flushes the
plug.
preemption itself is perfectly fine wrt any per-thread data updates
etc, but if preemption then also *changes* the data that is updated,
that's not great.
So that worries me.
Linus
