On Thu, Jul 10, 2014 at 12:53 PM, Keith Busch <keith.busch@xxxxxxxxx> wrote: > On Thu, 10 Jul 2014, Bjorn Helgaas wrote: >> >> [+cc LKML, Greg KH for driver core async shutdown question] >> On Tue, Jun 24, 2014 at 10:48:57AM -0600, Keith Busch wrote: >>> >>> To provide context why I want to do this asynchronously, NVM-Express has >>> one PCI device per controller, of which there could be dozens in a >>> system, >>> and each one may take many seconds (I've heard over ten in some cases) >>> to safely shutdown. >> >> >> I don't see anything in device_shutdown() that would wait for this >> sort of asynchronous shutdown to complete. So how do we know it's >> finished before we turn off the power, reset, kexec, etc.? >> >> If we need to do asynchronous shutdown, it seems like we need some >> sort of driver core infrastructure to manage that. > > > Yes, good point! To address that, I did submit this patch: > > http://lists.infradead.org/pipermail/linux-nvme/2014-May/000827.html > > I need to fix the EXPORT_SYMBOL_GPL usage for a v2, but before that, I > wan't to know the reason the driver can't use MSIx in an async shutdown > shutdown, and came to the patch mentioned above. > > I'd originally had the async shutdown use legacy interrupts, but I > know some NVMe devices do not support legacy, so can't use my original > proposal. If I can't rely on MSI/MSI-x being enabled in an async shutdown, > then I have to add polling, which I suppose we can live with. OK, I wasn't aware of your async shutdown patch. Given that, I would think we'd want to somehow delay the rest of pci_device_shutdown() until after the driver's async shutdown completes. We don't want to do either the MSI shutdown or the pci_clear_master() until after it completes, do we? And if we delay that, there would be no need to move the MSI shutdown from the core to the driver. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
