Re: [PATCH 1/4] PM: Introduce destroy_suspended_device()

Rafael J. Wysocki
2008-01-05T11:53:53Z

On Saturday, 5 of January 2008, Alan Stern wrote:
> On Fri, 4 Jan 2008, Rafael J. Wysocki wrote:
>
> > I have rebased gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch
> > on top of the $subject series, the result is appended. It has only been
> > compilation tested for now, but I'll be testing it for the next couple of days.
> >
> > Please review.
>
> I would prefer it if you could also merge in this patch at the same
> time:
>
> https://lists.linux-foundation.org/pipermail/linux-pm/2007-December/015921.html

Makes sense, I will.

> > +void device_resume(void)
> > {
> > - sysdev_resume();
> > - dpm_power_up();
> > + might_sleep();
> > + dpm_resume();
> > + unlock_all_devices();
> > + unregister_dropped_devices();
> > + up_write(&pm_sleep_rwsem);
> > }
>
> With the aforementioned patch merged in, this will generate a
> warning for each dropped device. The call to
> unregister_dropped_devices() should come after the up_write().
>
> You might also consider adding a call to unregister_dropped_devices()
> in the error path of device_suspend() -- in theory even an aborted
> suspend might cause a device to malfunction.

In fact it already works like this, since device_suspend() now calls the entire
device_resume() on error.

> Otherwise this looks okay.

However, I think we don't need to wait with unregistering suspended devices
until after the other ones are resumed. We only need a special function for
unregistering suspended devices that will make the PM core release the device's
semaphore before unregistering it.

I have already sent a replacemet for
gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch that includes
some code from the $subject patch and implements the above idea:

http://lkml.org/lkml/2008/1/4/278

I'm going to merge it with your patch at:
https://lists.linux-foundation.org/pipermail/linux-pm/2007-December/015921.html
and with patches [2/4] and [4/4] from the $subject series. I'll post the
result for a review later today.

Thanks,
Rafael