On Tuesday 08 December 2009, Alan Stern wrote: > On Tue, 8 Dec 2009, Rafael J. Wysocki wrote: > > > > This is a little more awkward because it requires the parent to iterate > > > through its children. > > > > I can live with that. > > > > > But it does solve the off-tree dependency problem for suspends. > > > > That's a plus, but I still think we're trying to create a barrier-alike > > mechanism using lock. > > > > There's one more possibility to consider, though. What if we use a completion > > instead of the flag + wait queue? It surely is a standard synchronization > > mechanism and it seems it might work here. > > You're right. I should have thought of that. Linus's original > approach couldn't use a completion because during suspend it needed to > make one task (the parent) wait for a bunch of others (the children). > But if you iterate through the children by hand, that objection no > longer applies. BTW, is there a good reason why completion_done() doesn't use spin_lock_irqsave and spin_unlock_irqrestore? complete() and complete_all() use them, so why not here? Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
