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

[Rafael J. Wysocki]

On Thursday 06 May 2010, Alan Stern wrote:
> 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.

This routine will be run from a freezable workqueue.

Rafael
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