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

[Alan Stern]

On Tue, 27 Apr 2010, [UTF-8] Arve Hjønnevåg 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

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