Messages in this thread | | | Date | Tue, 3 Sep 2019 13:06:07 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH 08/11] usb: Add USB subsystem notifications [ver #7] |
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On Tue, 3 Sep 2019, David Howells wrote:
> Guenter Roeck <linux@roeck-us.net> wrote: > > > > > This added call to usbdev_remove() results in a crash when running > > > > the qemu "tosa" emulation. Removing the call fixes the problem. > > > > > > Yeah - I'm going to drop the bus notification messages for now. > > > > > It is not the bus notification itself causing problems. It is the > > call to usbdev_remove(). > > Unfortunately, I don't know how to fix it and don't have much time to > investigate it right now - and it's something that can be added back later.
The cause of your problem is quite simple:
static int usbdev_notify(struct notifier_block *self, unsigned long action, void *dev) { switch (action) { case USB_DEVICE_ADD: + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_ADD, 0); break; case USB_DEVICE_REMOVE: + post_usb_device_notification(dev, NOTIFY_USB_DEVICE_REMOVE, 0); + usbdev_remove(dev); + break; + case USB_BUS_ADD: + post_usb_bus_notification(dev, NOTIFY_USB_BUS_ADD, 0); + break; + case USB_BUS_REMOVE: + post_usb_bus_notification(dev, NOTIFY_USB_BUS_REMOVE, 0); usbdev_remove(dev); break; }
The original code had usbdev_remove(dev) under the USB_DEVICE_REMOVE case. The patch mistakenly moves it, putting it under the USB_BUS_REMOVE case.
If the usbdev_remove() call were left where it was originally, the problem would be solved.
Alan Stern
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