Hi, On Fri, Apr 12, 2013 at 01:55:02AM +0000, Paul Zimmerman wrote: > > From: Felipe Balbi [mailto:balbi@xxxxxx] > > Sent: Tuesday, April 09, 2013 12:42 AM > > > > On Tue, Apr 09, 2013 at 02:36:51AM +0000, Paul Zimmerman wrote: > > > I'm getting a crash when I rmmod the dwc3-pci driver in latest Linus, and > > > also in 3.8.6 and 3.8.0. > > > > > > Screenshot (two parts) are here: > > > http://ompldr.org/vaTFibQ/IMG1.jpg > > > http://ompldr.org/vaTFicA/IMG2.jpg > > > > > > Unfortunately the very first part of the crash has scrolled off the > > > screen. > > > > > > I've decoded the crash a bit. The call chain descends through > > > platform_device_unregister(glue->dwc3) in dwc3_pci_remove(). It hits the > > > warning in kobject_put(): > > > > > > void kobject_put(struct kobject *kobj) > > > { > > > if (kobj) { > > > if (!kobj->state_initialized) > > > WARN(1, KERN_WARNING "kobject: '%s' (%p): is not " > > > "initialized, yet kobject_put() is being " > > > "called.\n", kobject_name(kobj), kobj); > > > kref_put(&kobj->kref, kobject_release); > > > } > > > } > > > > > > and crashes when it tries to print the string, presumably because the > > > kobj->name field is either NULL or poisoned. So probably the kobject has > > > already been freed, or is in the process of being freed? > > > > > > Any ideas? Any debugging hints? > > > > looks like the PHY is being unregistered too early. I believe that's > > because PHY's dev is just a pointer to the real dev and maybe that's > > what's wrong. > > > > Here's what happens: > > > > devm_usb_get_phy() will find the PHY and issue a get_device(phy->dev). > > phy->dev is initialized to (in your case) nop_xceiv's &pdev->dev. > > > > When you remove dwc3.ko, due to devm_usb_phy_get(), > > devm_usb_phy_release() will get called which will issue a > > put_device(phy->dev), and that will trigger nop_xceiv's platform_device > > release, once you remove dwc3-pci.ko, you see the trigger. > > > > I'm adding Kishon to the loop to help out figuring out what the best fix > > would be. > > I found out a couple more things about this. > > If I do "rmmod dwc3" first, and then do "rmmod dwc3-pci", it doesn't > crash. > > On a related note, if I just do "modprobe dwc3-pci", then dwc3.ko > doesn't get loaded. I have to do "modprobe dwc3" too, to get > everything loaded. Shouldn't dwc3.ko be a dependency of dwc3-pci.ko, > and get loaded automatically? Could this missing dependency also > explain the crash on "rmmod dwc3-pci"? there are no direct dependencies between those two modules other than the fact that dwc3-pci.ko creates dwc3.ko's struct platform_device. That, however, should be enough for udev to load the proper module. If it's not loading, that's usually a bogus (or lack thereof) MODULE_ALIAS(). -- balbi
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