linux-kernel - [PATCH v2 06/15] serial: sc16is7xx: use guards for simple mutex locks

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Message-Id: <20251002145738.3250272-7-hugo@hugovil.com>
Date: Thu,  2 Oct 2025 10:57:29 -0400
From: Hugo Villeneuve <hugo@...ovil.com>
To: gregkh@...uxfoundation.org,
	jirislaby@...nel.org,
	fvallee@...rea.fr
Cc: linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	hugo@...ovil.com,
	Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: [PATCH v2 06/15] serial: sc16is7xx: use guards for simple mutex locks

From: Hugo Villeneuve <hvilleneuve@...onoff.com>

Guards can help to make the code more readable, so use them wherever they
do so.

In sc16is7xx_port_irq(), labels and 'rc' locals are eliminated completely.

Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>

---

Based on patch by Jiri Slaby (SUSE) <jirislaby@...nel.org>:
commit("serial: use guards for simple mutex locks")
---
 drivers/tty/serial/sc16is7xx.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 335695d0e7aa7..1acf5be03d489 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -11,6 +11,7 @@
 #define DEFAULT_SYMBOL_NAMESPACE "SERIAL_NXP_SC16IS7XX"
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -778,18 +779,15 @@ static void sc16is7xx_update_mlines(struct sc16is7xx_one *one)
 
 static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 {
-	bool rc = true;
 	unsigned int iir, rxlen;
 	struct uart_port *port = &s->p[portno].port;
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
-	mutex_lock(&one->lock);
+	guard(mutex)(&one->lock);
 
 	iir = sc16is7xx_port_read(port, SC16IS7XX_IIR_REG);
-	if (iir & SC16IS7XX_IIR_NO_INT_BIT) {
-		rc = false;
-		goto out_port_irq;
-	}
+	if (iir & SC16IS7XX_IIR_NO_INT_BIT)
+		return false;
 
 	iir &= SC16IS7XX_IIR_ID_MASK;
 
@@ -829,10 +827,7 @@ static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 		break;
 	}
 
-out_port_irq:
-	mutex_unlock(&one->lock);
-
-	return rc;
+	return true;
 }
 
 static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
@@ -873,9 +868,8 @@ static void sc16is7xx_tx_proc(struct kthread_work *ws)
 	    (port->rs485.delay_rts_before_send > 0))
 		msleep(port->rs485.delay_rts_before_send);
 
-	mutex_lock(&one->lock);
+	guard(mutex)(&one->lock);
 	sc16is7xx_handle_tx(port);
-	mutex_unlock(&one->lock);
 }
 
 static void sc16is7xx_reconf_rs485(struct uart_port *port)
@@ -942,9 +936,8 @@ static void sc16is7xx_ms_proc(struct kthread_work *ws)
 	struct sc16is7xx_port *s = dev_get_drvdata(one->port.dev);
 
 	if (one->port.state) {
-		mutex_lock(&one->lock);
-		sc16is7xx_update_mlines(one);
-		mutex_unlock(&one->lock);
+		scoped_guard(mutex, &one->lock)
+			sc16is7xx_update_mlines(one);
 
 		kthread_queue_delayed_work(&s->kworker, &one->ms_work, HZ);
 	}
-- 
2.39.5