This is a note to let you know that I've just added the patch titled USB: cdc-acm: fix break reporting to the 4.9-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-break-reporting.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 58fc1daa4d2e9789b9ffc880907c961ea7c062cc Mon Sep 17 00:00:00 2001 From: Johan Hovold <johan@xxxxxxxxxx> Date: Wed, 29 Sep 2021 11:09:37 +0200 Subject: USB: cdc-acm: fix break reporting From: Johan Hovold <johan@xxxxxxxxxx> commit 58fc1daa4d2e9789b9ffc880907c961ea7c062cc upstream. A recent change that started reporting break events forgot to push the event to the line discipline, which meant that a detected break would not be reported until further characters had been receive (the port could even have been closed and reopened in between). Fixes: 08dff274edda ("cdc-acm: fix BREAK rx code path adding necessary calls") Cc: stable@xxxxxxxxxxxxxxx Acked-by: Oliver Neukum <oneukum@xxxxxxxx> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210929090937.7410-3-johan@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/class/cdc-acm.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -349,6 +349,9 @@ static void acm_ctrl_irq(struct urb *urb acm->iocount.overrun++; spin_unlock(&acm->read_lock); + if (newctrl & ACM_CTRL_BRK) + tty_flip_buffer_push(&acm->port); + if (difference) wake_up_all(&acm->wioctl); Patches currently in stable-queue which might be from johan@xxxxxxxxxx are queue-4.9/usb-cdc-acm-fix-break-reporting.patch queue-4.9/usb-cdc-acm-fix-racy-tty-buffer-accesses.patch