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Date: Sun, 2 Aug 2009 23:09:37 +0200
Message-ID: <81b0412b0908021409h73fc2fcfo64c4ba9ee1f0d552@mail.gmail.com>
Subject: Re: Oops in CDC ACM after an Openmoko phone (neo1973) changes its usb 
	interface from ACM to Ethernet
From: Alex Riesen <raa.lkml@gmail.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>, linux-usb@vger.kernel.org,
       Oliver Neukum <oliver@neukum.name>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Greg Kroah-Hartman <greg@kroah.com>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>
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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