On Mon, Mar 09, 2009 at 12:36:54AM -0600, Alex Chiang wrote: > Hi Kay, Greg, > > I've been working on this patch series recently that adds > function and device level hotplug into the PCI core: > > http://thread.gmane.org/gmane.linux.kernel.pci/3495 > > For the last two weeks, I've been beating my head against a > refcounting/kobject problem, and was hoping you could give me > some advice, since I seem to have run into a wall. > > My test case has been removing device 0000:04:00.0, which should > remove all the devices below it. You are removing the children before the parent device, right? If not, you have to be _very_ careful (personally, I don't think you should be allowed to do that, but others, like the scsi developers, like doing things like this...) > +-[0000:03]---00.0-[0000:04-07]----00.0-[0000:05-07]--+-02.0-[0000:06]--+-00.0 Intel Corporation 82571EB Quad Port Gigabit Mezzanine Adapter > | | \-00.1 Intel Corporation 82571EB Quad Port Gigabit Mezzanine Adapter > | \-04.0-[0000:07]--+-00.0 Intel Corporation 82571EB Quad Port Gigabit Mezzanine Adapter > | \-00.1 Intel Corporation 82571EB Quad Port Gigabit Mezzanine Adapter > > I can remove the device and rescan the bus once, and it works > fine. The second removal works fine, and then, unpredictably, > later rescan/remove cycles eventually end up producing a warning > and oops every time. Sometimes I die on the 2nd rescan, sometimes > not until the 4th or 5th remove/rescan cycle. What is the warning and oops? > In this data set, I turned on kobject debugging, and managed to > capture a trace where we die on the 2nd rescan. > > In this data set, we: > > - create a kobject for 0000:04:00.0 (e00000018cac2920) > - remove the device > - observe '0000:04:00.0' (e00000018cac2920): calling ktype release > - rescan the bus > - discover that e00000018cac2920 is still hanging around! What do you mean by "rescan"? And sure, if you create a new device, it could be allocated at the same location, that's what the slab allocators do, right? Can you provide the full debug log that shows the problem? thanks, greg k-h -- 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
