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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Oliver Neukum <oneukum@suse.com>,
        Johan Hovold <johan@kernel.org>
Subject: [PATCH 4.19 03/28] USB: cdc-acm: fix break reporting
Date:   Mon, 11 Oct 2021 15:46:53 +0200
Message-Id: <20211011134640.825082949@linuxfoundation.org>
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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
@@ -339,6 +339,9 @@ static void acm_process_notification(str
 			acm->iocount.overrun++;
 		spin_unlock_irqrestore(&acm->read_lock, flags);
 
+		if (newctrl & ACM_CTRL_BRK)
+			tty_flip_buffer_push(&acm->port);
+
 		if (difference)
 			wake_up_all(&acm->wioctl);