This is a note to let you know that I've just added the patch titled USB: cdc-acm: fix device unregistration to the 3.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-cdc-acm-fix-device-unregistration.patch and it can be found in the queue-3.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From cb25505fc604292c70fc02143fc102f54c8595f0 Mon Sep 17 00:00:00 2001 From: Johan Hovold <jhovold@xxxxxxxxx> Date: Tue, 19 Mar 2013 09:21:06 +0100 Subject: USB: cdc-acm: fix device unregistration From: Johan Hovold <jhovold@xxxxxxxxx> 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@xxxxxxx> Cc: Oliver Neukum <oneukum@xxxxxxx> Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/class/cdc-acm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -601,7 +601,6 @@ static void acm_port_destruct(struct tty 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); @@ -1418,6 +1417,8 @@ static void acm_disconnect(struct usb_in 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); Patches currently in stable-queue which might be from jhovold@xxxxxxxxx are queue-3.4/usb-cdc-acm-fix-device-unregistration.patch queue-3.4/usb-serial-fix-interface-refcounting.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html