On Tuesday, November 30, 2010, Alan Stern wrote: > On Mon, 29 Nov 2010, Rafael J. Wysocki wrote: > > > > Oh, I see. This is a tricky issue. Every driver for a device that can > > > have wakeup-enabled children needs to worry about the race between > > > suspending the device and receiving a wakeup request from a child. > > > For example, in drivers/usb/core/hcd-pci.c, the suspend_common() > > > routine goes out of its way to return -EBUSY if device_may_wakeup() is > > > true and the controller's root hub has a pending wakeup request. > > > > > > How should drivers handle this in general? Should we make an effort to > > > convert them to use the wakeup framework so they they can let the PM > > > core take care of these races? > > > > I think so. > > > > We also need to put a pm_check_wakeup_events() check into dpm_suspend() IMO, > > so that we abort the suspending of devices as soon as a wakeup event is > > reported. > > You might as well add that into this patch. I'll do that in a separate patch. > > > Do we have to consider similar races during runtime suspend? > > > > Ideally, yes, but I'm not sure if that's generally possible. IMO, it won't be > > a big deal if a parent device is suspended and immediately resumed occasionally > > due to a pending wakeup signal from one of its children. It may be a problem > > if that happens too often, though. > > Okay. > > > Does it mean you're fine with the patch? > > Provided you repair the error that Lei Ming pointed out. That's the > problem with functions that return Boolean values -- you have to name > them very carefully. Ideally the name should be a predicate or a > question. I already have fixed it. The name is unfortunate indeed, perhaps it's better to call that function pm_new_wakeup_events() or something like this. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
