linux-kernel - Re: PROBLEM: Removing Huawei E220 HSDPA Modem causes system to completely hang

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Date:	Mon, 8 Jun 2009 16:20:03 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Jonathan Cervidae <jonathan.cervidae@...il.com>
cc:	Jiri Kosina <jkosina@...e.cz>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: PROBLEM: Removing Huawei E220 HSDPA Modem causes system to
 completely hang

On Mon, 8 Jun 2009, Jiri Kosina wrote:

> [ added linux-usb to CC and kept the whole original mail for reference ]
> 
> On Mon, 8 Jun 2009, Jonathan Cervidae wrote:
> 
> > While at first the easy fix to this issue would be "Don't remove modem", 
> > sometimes it resets itself and therefore appears to disconnect and 
> > reconnect which causes the system crash.
> 
> What is the product ID of the device? (lsusb will tell you).
> 
> > I can reproduce the problem 80% of the time by ripping the modem out of 
> > the USB port. However, if I kill -9 pppd before doing it, it never 
> > happens so the problem appears to be an interaction between pppd and the 
> > kernel. As full system lockups in my limited knowledge must be kernel 
> > problems since systems should never fully lock (with flashing caps lock 
> > and scroll lock lights, not responsive to magic sysreq keys) presumably 
> > this is a kernel bug.
> > 
> > It also did not happen until recently, some point within the last month. I 
> > would have reported it earlier (and reverted to a kernel that didn't do it) 
> > but didn't realise why it was happening.

Two patches for usb-serial drivers were posted recently to fix this 
sort of problem:

	http://marc.info/?l=linux-usb&m=124395806322087&w=2
	http://marc.info/?l=linux-usb&m=124395806222085&w=2

See if the two of them together solve everything.

Alan Stern

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