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. > > 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. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
