Re: [PATCH 1/8] PM: Add suspend block api.

Alan Stern
2010-05-06T15:18:05Z

On Tue, 27 Apr 2010, [UTF-8] Arve HjÃ¸nnevÃ¥g wrote:

> +static void suspend_worker(struct work_struct *work)
> +{
> + int ret;
> + int entry_event_num;
> +
> + enable_suspend_blockers = true;
> + while (!suspend_is_blocked()) {
> + entry_event_num = current_event_num;
> +
> + if (debug_mask & DEBUG_SUSPEND)
> + pr_info("suspend: enter suspend\n");
> +
> + ret = pm_suspend(requested_suspend_state);
> +
> + if (debug_mask & DEBUG_EXIT_SUSPEND)
> + pr_info_time("suspend: exit suspend, ret = %d ", ret);
> +
> + if (current_event_num == entry_event_num)
> + pr_info("suspend: pm_suspend returned with no event\n");
> + }
> + enable_suspend_blockers = false;
> +}

Here's a completely new issue. When using opportunistic suspends on an
SMP system, it could happen that the system gets a wakeup event and
this routine starts running again before the event's IRQ handler has
finished (or has enabled a suspend blocker). The system would
re-suspend too soon.

Is there anything in the PM core that waits until all outstanding IRQs
have been handled before unfreezing processes? If there is, I can't
find it. Should such a thing be added?

Alan Stern