Re: Oops in CDC ACM after an Openmoko phone (neo1973) changes its usb interface from ACM to Ethernet

[Alex Riesen <raa.lkml@gmail.com>]

On Sun, Aug 2, 2009 at 22:50, Alan Stern<stern@rowland.harvard.edu> wrote:
> On Sun, 2 Aug 2009, Alex Riesen wrote:
>
>> Any idea how to disable stack dumps so that there is more place
>> for other output on a laptop screen? (no chance for serial console)
>
> Put a "return" statement at the start of dump_stack().
>

That wasn't enough, but a "return" in die helped.

So, I connect the device, run its bootloader, which causes
a CDC ACM interface to appear. The /dev/ttyACM0 node
appears, and I open it (with minicom). Then I just switch
the device off and kernel oopses with:

uhci_hcd 0000:00:1d.0: release dev 4 ep81-INT, period 128, phase 0, 23 us
usb 5-1: uhci_result_common: failed with status 440000
usb 5-1: uhci_result_common: failed with status 440000
uhci_hcd 0000:00:1d.0: shutdown urb ffff88007de6bf00 ep3in-bulk
BUG: unable to handle kernel NULL pointer dereference at 0000000000000003
IP: [<ffffffffa005ce38>] acm_rx_tasklet+0x24e/0x3a3 [cdc_acm]
... something will be missing here
---[ end trace ...]---
Kernel panic - not syncing: Fatal exception in interrupt