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USB: cdc-acm: fix device unregistration 

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.

Cc: stable <stable@vger.kernel.org>
Cc: Oliver Neukum <oneukum@suse.de>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Johan Hovold 2013-03-19 09:21:06 +01:00 committed by Greg Kroah-Hartman
parent c93d819550
commit cb25505fc6
1 changed files with 2 additions and 1 deletions
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3
drivers/usb/class/cdc-acm.c
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@ -593,7 +593,6 @@ static void acm_port_destruct(struct tty_port *port)
dev_dbg(&acm->control->dev, "%s\n", __func__);
tty_unregister_device(acm_tty_driver, acm->minor);
acm_release_minor(acm);
usb_put_intf(acm->control);
kfree(acm->country_codes);
@ -1426,6 +1425,8 @@ static void acm_disconnect(struct usb_interface *intf)
stop_data_traffic(acm);
tty_unregister_device(acm_tty_driver, acm->minor);
usb_free_urb(acm->ctrlurb);
for (i = 0; i < ACM_NW; i++)
usb_free_urb(acm->wb[i].urb);