On Thu, 6 May 2010, Rafael J. Wysocki wrote: > > Here's a completely new issue. When using opportunistic suspends on an > > SMP system, it could happen that the system gets a wakeup event and > > this routine starts running again before the event's IRQ handler has > > finished (or has enabled a suspend blocker). The system would > > re-suspend too soon. > > This routine will be run from a freezable workqueue. But how do you know that processes won't get unfrozen until all the pending IRQs have been handled? Imagine something like this: CPU 0 CPU 1 ----- ----- Wake up non-boot CPUs Resume devices Invoke the IRQ handler [ CPU 0 should wait here for the handler to finish, but it doesn't ] Defrost threads Handler running... Workqueue routine runs Start another suspend Handler enables a suspend blocker, but it's too late Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
