On 2015/3/12 9:17, Rafael J. Wysocki wrote: > On Wednesday, March 11, 2015 10:04:42 PM Luck, Tony wrote: >>>> Unfortunately there's a long standing comment in pci_device_remove(): >>>> >>>> /* >>>> * 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... >>>> */ >>>> >>>> So, unless we can somehow ignore that comment, I suspect forcing the >>>> device to be disabled on driver remove, whether done from pci-core or >>>> from x86/pci, is going to cause all sorts of breakage. Are the >>>> expectations set by b4b55cda5874 really valid? It seems like something >>>> needs to be done to allow the IRQ to be automatically re-established on >>>> x86 regardless of the driver doing the right thing when releasing the >>>> device. We're still looking at a regression for v4.0 as a result of >>>> b4b55cda5874. >>> >>> In which case we probably should revert commit b4b55cda5874 for the time being. >>> >>> At least I'd be very nervous about any ad-hoc fixes at this stage of the cycle. >> >> The comment goes back to the dawn of "git" time ... not sure how much further >> back. >> >> Is this actually still an issue on modern systems? Maybe we need a black list >> or white list to separate the good from bad systems? > > The answer to that is "We don't know" and in my not so humble opinion it is too > risky to try to find out at the end of the cycle. Hi Rafael and Alex, How about a patch which: 1) gives a warning if PCI device is still enabled when unloading driver 2) release PCI interrupt only if PCI device is disabled. By this way, we could support IOAPIC hot-removal on latest platforms and avoid regressions on old platforms. Thanks! Gerry -- 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
