USB: cdc-acm: fix device unregistration
authorJohan Hovold <jhovold@gmail.com>
Tue, 19 Mar 2013 08:21:06 +0000 (09:21 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 28 Mar 2013 19:18:02 +0000 (12:18 -0700)
commit5557c6706441e7ad797b8b5c95579a9a1146502b
tree11bb8f3fc42039695d29dcd7177b78a906fb5342
parent5a8d2f76c000f12e8985a64d0c8b45f0c746fc43
USB: cdc-acm: fix device unregistration

commit cb25505fc604292c70fc02143fc102f54c8595f0 upstream.

Unregister tty device in disconnect as is required by the USB stack.

By deferring unregistration to when the last tty reference is dropped,
the parent interface device can get unregistered before the child
resulting in broken hotplug events being generated when the tty is
finally closed:

KERNEL[2290.798128] remove   /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:3.1 (usb)
KERNEL[2290.804589] remove   /devices/pci0000:00/0000:00:1d.7/usb2/2-1 (usb)
KERNEL[2294.554799] remove   /2-1:3.1/tty/ttyACM0 (tty)

The driver must deal with tty callbacks after disconnect by checking the
disconnected flag. Specifically, further opens must be prevented and
this is already implemented.

Acked-by: Oliver Neukum <oneukum@suse.de>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/class/cdc-acm.c