[PATCH 4.4 02/18] USB: cdc-acm: fix break reporting

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Johan Hovold <johan@kernel.org>

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@vger.kernel.org
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210929090937.7410-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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
@@ -348,6 +348,9 @@ 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);