linux-kernel - [PATCH 1/6] tty: simplify throttling using guard()s

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Message-ID: <20250425111315.1036184-2-jirislaby@kernel.org>
Date: Fri, 25 Apr 2025 13:13:10 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 1/6] tty: simplify throttling using guard()s

tty_throttle_safe() and tty_unthrottle_safe can be made less convoluted
using guard()s. Switch them.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
 drivers/tty/tty_ioctl.c | 50 +++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 85de90eebc7b..90c70d8d14e3 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -122,21 +122,19 @@ EXPORT_SYMBOL(tty_unthrottle);
  */
 bool tty_throttle_safe(struct tty_struct *tty)
 {
-	bool ret = true;
-
-	mutex_lock(&tty->throttle_mutex);
-	if (!tty_throttled(tty)) {
-		if (tty->flow_change != TTY_THROTTLE_SAFE)
-			ret = false;
-		else {
-			set_bit(TTY_THROTTLED, &tty->flags);
-			if (tty->ops->throttle)
-				tty->ops->throttle(tty);
-		}
-	}
-	mutex_unlock(&tty->throttle_mutex);
+	guard(mutex)(&tty->throttle_mutex);
 
-	return ret;
+	if (tty_throttled(tty))
+		return true;
+
+	if (tty->flow_change != TTY_THROTTLE_SAFE)
+		return false;
+
+	set_bit(TTY_THROTTLED, &tty->flags);
+	if (tty->ops->throttle)
+		tty->ops->throttle(tty);
+
+	return true;
 }
 
 /**
@@ -152,21 +150,19 @@ bool tty_throttle_safe(struct tty_struct *tty)
  */
 bool tty_unthrottle_safe(struct tty_struct *tty)
 {
-	bool ret = true;
+	guard(mutex)(&tty->throttle_mutex);
 
-	mutex_lock(&tty->throttle_mutex);
-	if (tty_throttled(tty)) {
-		if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
-			ret = false;
-		else {
-			clear_bit(TTY_THROTTLED, &tty->flags);
-			if (tty->ops->unthrottle)
-				tty->ops->unthrottle(tty);
-		}
-	}
-	mutex_unlock(&tty->throttle_mutex);
+	if (!tty_throttled(tty))
+		return true;
 
-	return ret;
+	if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
+		return false;
+
+	clear_bit(TTY_THROTTLED, &tty->flags);
+	if (tty->ops->unthrottle)
+		tty->ops->unthrottle(tty);
+
+	return true;
 }
 
 /**
-- 
2.49.0