Hello, Rafael. On Wed, Apr 23, 2014 at 06:12:01PM +0200, Rafael J. Wysocki wrote: > >Why add this additional global lock across multiple subsystems? > > That basically is because of how eject works when it is triggered via ACPI. > > It is signaled for a device at the top of a subtree. It may be a > container of some sort and the eject involves everything below that > device in the ACPI namespace. That may involve multiple subsystem > (CPUs, memory, PCI host bridge, etc.). > > We do that in two steps, offline (which can fail) and eject proper > (which can't fail and makes all of the involved devices go away). > All that has to be done in one go with respect to the > sysfs-triggered offline/online and that's why the lock is there.
Ah, okay, so it's actually synchronzing across multiple subsystems. I think it definitely calls for more documentation. The requirement is pretty unusual after all. Thanks! -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
