From beb1479f6d8f359110ec334a972f979874cd7ad2 Mon Sep 17 00:00:00 2001
From: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Date: Tue, 19 Sep 2023 10:51:54 +0200
Subject: [PATCH] tty: early return from send_break() on
 TTY_DRIVER_HARDWARE_BREAK

References: bsc#1214683 (PREEMPT_RT prerequisite backports)
Patch-mainline: v6.6.14
Git-commit: 66619686d187b4a6395316b7f39881e945dce4bc

[ Upstream commit 66619686d187b4a6395316b7f39881e945dce4bc ]

If the driver sets TTY_DRIVER_HARDWARE_BREAK, we leave ops->break_ctl()
to the driver and return from send_break(). But we do it using a local
variable and keep the code flowing through the end of the function.
Instead, do 'return' immediately with the ops->break_ctl()'s return
value.

This way, we don't have to stuff the 'else' branch of the 'if' with the
software break handling. And we can re-indent the function too.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230919085156.1578-14-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 66aad7d8d3ec ("usb: cdc-acm: return correct error code on unsupported break")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 drivers/tty/tty_io.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 383159639f65..92d2da9256ef 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2475,22 +2475,24 @@ static int send_break(struct tty_struct *tty, unsigned int duration)
 		return 0;
 
 	if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
-		retval = tty->ops->break_ctl(tty, duration);
-	else {
-		/* Do the work ourselves */
-		if (tty_write_lock(tty, false) < 0)
-			return -EINTR;
-		retval = tty->ops->break_ctl(tty, -1);
-		if (retval)
-			goto out;
-		if (!signal_pending(current))
-			msleep_interruptible(duration);
-		retval = tty->ops->break_ctl(tty, 0);
+		return tty->ops->break_ctl(tty, duration);
+
+	/* Do the work ourselves */
+	if (tty_write_lock(tty, false) < 0)
+		return -EINTR;
+
+	retval = tty->ops->break_ctl(tty, -1);
+	if (retval)
+		goto out;
+	if (!signal_pending(current))
+		msleep_interruptible(duration);
+	retval = tty->ops->break_ctl(tty, 0);
 out:
-		tty_write_unlock(tty);
-		if (signal_pending(current))
-			retval = -EINTR;
-	}
+	tty_write_unlock(tty);
+
+	if (signal_pending(current))
+		retval = -EINTR;
+
 	return retval;
 }