On Thu, 25 Jun 2009, Rafael J. Wysocki wrote: > > The whole business about the runtime_notify and RPM_NOTIFY flags is > > impenetrable. My suggestion: Rename runtime_notify to notify_pending > > and eliminate RPM_NOTIFY. Then make sure that notify_pending is set > > whenever a notify work item is queued. > > I was going to do exactly that, but I realized it wouldn't work in general, > because ->runtime_idle() could run __pm_runtime_suspend() in theory. I'll cut this short by noting the dilemma. If the runtime_idle callback does a synchronous suspend, and __pm_runtime_suspend sees the status is already RPM_SUSPENDING, then it will wait for the suspend to finish. Hence it's not safe to do cancel_work_sync from within __pm_runtime_suspend; it might deadlock. It occurs to me that the problem would be solved if were a cancel_work routine. In the same vein, it ought to be possible for cancel_delayed_work to run in interrupt context. I'll see what can be done. What do you think about adding a version of pm_runtime_put that would call pm_runtime_idle directly when the counter reaches 0, instead of queuing an idle request? I feel that drivers should have a choice about which sort of notification to use. > > And don't forget to decrement the parent's child_count again if the resume > > fails. > > I didn't _forget_it, because the device can't be RPM_SUSPENDED after > __pm_runtime_resume(). You're right; that fact escaped me. > > In __pm_runtime_suspend, you should decrement the parent's child_count > > before releasing the child's lock. > > Why exactly is that necessary? I guess it isn't. But it won't hurt to keep the parent's counter synchronized with the child's state as closely as possible. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
