Disconnect of USB Serial device not notifying application

A Multi-Tech MT5634ZBA-USB modem uses the cdc-acm driver. If you are in
an application (kermit, mgetty, pppd) waiting on a select operation and
the USB cable is removed, it appears that an error is raised and the
select is terminated causing the application to "take notice" that the
device was removed. 
 
The new MT9234ZBA-USB modem uses the ti_usb_3410_5052 driver which
relies on usb-serial. If you remove the USB cable when using this
driver, the application remains running and does not realize that the
device is now gone. This was tested on 2.6.9, which I realize is an old
release in kernel years, but it is not clear to me that there have been
any changes which might effect this. Is this expected behavior? Or
should some error be raised when the device is disconnected?
 
I have tried a variety of modifications where I have had the
ti_usb_3410_5052 driver wrap the usb_serial_disconnect routine so that I
could inject some additional processing before and after the call.
Nothing has worked. My added processing either has no effect or causes a
kernel panic. Is there something I could add to the ti_usb_3410_5052
driver so that an error is raised upon the USB cable being disconnected.
What can I do to effect the select operation in use by the application?
 
The reason for tying this to the 2.6.9 kernel is that this is a customer
problem where they say they can't change the kernel or add any kernel
modifications. This greatly limits what can be done to solve the
problem. I can only change the source code for the ti_usb_3410_5052
driver. Yeah, I know I'm in trouble. 
 
Any help is be greatly appreciated. 
 
Thank you,
Dale
 
________________________________

Dale Martenson | Manager of Software Development | Multi-Tech Systems,
Inc. Voice + 763.717.5519 | Fax + 763.717.5983 |
[email protected] <mailto:[email protected]>  | 2205
Woodale Drive, Mounds View, MN 55112 

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