On 2017/11/6 19:32, Greg KH wrote:
>> A simple process is as below:
>> xhci_plat_probe()
>> |
>> usb_add_hcd() xhci_plat_remove()
>> | |
>> find some device usb_remove_hcd()
>> | |
>> hub_port_connect() -> usb_alloc_dev() usb_disconnect()
>> | |
>> before hub_enable_device() xhci_stop()
>> |
>> xhci_mem_cleanup()
>> |
>>
>> xhci_free_virt_devices_depth_first()
>> |
>> real_port is 0 access
>> xhci->rh_bw[vdev->real_port-1]
>>
>> The problem came from https://bugs.96boards.org/show_bug.cgi?id=535
>> Also look at crbug.com/700041
>
> Then the bug needs to be fixed, throwing a huge kernel trace message
> into the kernel log is not "fixing" the problem at all, right?
>
> thanks,
>
> greg k-h
>
> .
>
You are right, the way that xhci_plat_remove() to be called needs to be fixed.
But there is still possibility for this crash.
What do you think if just add an "xhci_warn" instead of "WARN_ON"?
+ if (!vdev->real_port) {
+ xhci_warn(xhci, "Bad vdev->real_port\n");
+ goto out;
+ }
+
Best regards
Yu Chen
