On Tuesday, May 13, 2014 11:12:28 AM Alan Stern wrote: > On Tue, 13 May 2014, Rafael J. Wysocki wrote: > > > > > + dev->power.direct_complete = ret > 0 && state.event == > > > > PM_EVENT_SUSPEND > > > > + && pm_runtime_suspended(dev); > > > > > > Shouldn't the flag be set under the spinlock? > > > > I guess you're worried about runtime PM flags being modified in parallel to > > this? But we've just done the barrier a while ago, so is that still a > > concern > > here? > > A wakeup request from the hardware could cause a runtime resume to > occur at this time. The barrier wouldn't prevent that. > > It's unlikely, I agree, but not impossible.
Yeah, I didn't think about that. But that also can occur in __device_suspend(), after we've checked the flag and decided not to invoke the ->suspend() callback, right? So moving the check in there doesn't help much I'd say. It closes the race window, but that's it. That means that the whole approach based on ->prepare() is problematic unless we somehow mix it with disabling runtime PM. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
