On Thursday, March 19, 2015 03:49:33 PM Jiang Liu wrote: > On 2015/3/19 6:11, Bjorn Helgaas wrote: > > On Tue, Mar 17, 2015 at 03:37:12PM +0800, Jiang Liu wrote: > >> To support IOAPIC hot-removal, we need to release PCI interrupt resource > >> when unbinding PCI device driver. But due to historical reason, > >> /* > >> * We would love to complain here if pci_dev->is_enabled is set, that > >> * the driver should have called pci_disable_device(), but the > >> * unfortunate fact is there are too many odd BIOS and bridge setups > >> * that don't like drivers doing that all of the time. > >> * Oh well, we can dream of sane hardware when we sleep, no matter how > >> * horrible the crap we have to deal with is when we are awake... > >> */ > > > > Quoting the comment here (especially the last two lines) is overkill and > > obscures the real point. The important thing is that some drivers have > > legitimate reasons for not calling pci_disable_device(). > Hi Bjorn, > Thanks for review. I will rewrite the commit message. > >> some drivers don't call pci_disable_device() when unloading, which > >> prevents us from reallocating PCI interrupt resource on reloading > >> PCI driver and causes regressions. > > > > This isn't very clear. I can believe that "drivers not calling > > pci_disable_device()" means we don't release IRQ resources, which might > > prevent you from hot-removing an IOAPIC. > > > > But "drivers not calling pci_disable_device()" doesn't cause regressions. > > > >> So release PCI interrupt resource only if PCI device is disabled when > >> unbinding. By this way, we could support IOAPIC hot-removal on latest > >> platforms and avoid regressions on old platforms. > > > > Does this mean you can only hot-remove IOAPICs if all drivers for devices > > using the IOAPIC call pci_disable_device()? If so, it seems sort of > > dubious that we have to rely on drivers for that. > This is a quickfix for v4.0 merging window. We will try to solve this > issue for next merging window. If that is the plan, then I'd rather revert the offending commit and try again in the next cycle. Bjorn, what do you think? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
