Re: [PATCH] PM: Acquire device locks on suspend

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Sunday, 6 of January 2008, Alan Stern wrote:
> On Sun, 6 Jan 2008, Rafael J. Wysocki wrote:
> 
> > > If you can figure out a way to disable the warning in device_del() for 
> > > just the one device being unregistered by 
> > > device_pm_destroy_suspended(),
> > 
> > Something like this, perhaps:
> > 
> > @@ -905,6 +915,18 @@ void device_del(struct device * dev)
> >  	struct device * parent = dev->parent;
> >  	struct class_interface *class_intf;
> >  
> > +	if (down_trylock(&dev->sem)) {
> > +		if (pm_sleep_lock()) {
> > +			dev_warn(dev, "Illegal %s during suspend\n",
> > +				__FUNCTION__);
> > +			dump_stack();
> > +		} else {
> > +			pm_sleep_unlock();
> > +		}
> > +	} else {
> > +		up(&dev->sem);
> > +	}
> > +
> >  	if (parent)
> >  		klist_del(&dev->knode_parent);
> >  	if (MAJOR(dev->devt))
> 
> Bizarre, but it should work.

OK

Still, shouldn't we fail the removal of the device apart from giving the
warning?

> Be sure to include plenty of explanatory comments

I will.

I think that code can be moved to its own function in
drivers/base/power/main.c, btw.

> -- otherwise nobody will be able to figure it out!  :-) 

Well, I guess so. :-)

Thanks,
Rafael