Re: [Bug 10030] Suspend doesn't work when SD card is inserted

Alan Stern
2008-02-21T17:49:14Z

On Thu, 21 Feb 2008, Rafael J. Wysocki wrote:

> > > --- linux-2.6.orig/drivers/base/core.c
> > > +++ linux-2.6/drivers/base/core.c
> > > @@ -929,6 +929,11 @@ void device_del(struct device *dev)
> > > struct device *parent = dev->parent;
> > > struct class_interface *class_intf;
> > >
> > > + if (in_suspend_context()) {
> > > + get_device(dev);
> >
> > Where is this get_device() undone? Shouldn't there be an extra
> > put_device() added to unregister_dropped_devices()?
>
> No, I don't think so, because unregister_dropped_devices() calls
> device_unregister() that does the put_device() eventually.

Ah, yes.

> If we are called by device_unregister(), the get_device() is needed to balance
> the put_device() that will be called by device_unregister() after we return.
>
> OTOH, if we are called directly, then we need to balance the put_device()
> that will be done by device_unregister() called from
> unregister_dropped_devices().
>
> I hope I didn't miss anything.

Okay, that sounds right.

> > > + device_pm_schedule_removal(dev);
> > > + return;
> > > + }
> > > device_pm_remove(dev);
> > > if (parent)
> > > klist_del(&dev->knode_parent);
> >
> > And now the change to device_destroy() isn't needed at all.
>
> No, it's not. Didn't I remove it? I thought I did.

Oh yes, you did.

I see a possible problem in device_resume(). My copy isn't fully
up-to-date, but it looks like you call unregister_dropped_devices()
before doing the up_write(&pm_sleep_rwsem). Won't this cause
warnings in device_del() about a suspicious caller?

Alan Stern