linux-kernel - [PATCH] tty: owl-uart: fix call balance of owl

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Message-Id: <20250213112416.1610678-1-mordan@ispras.ru>
Date: Thu, 13 Feb 2025 14:24:16 +0300
From: Vitalii Mordan <mordan@...ras.ru>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Vitalii Mordan <mordan@...ras.ru>,
	Jiri Slaby <jirislaby@...nel.org>,
	Andreas Färber <afaerber@...e.de>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Jeff Johnson <quic_jjohnson@...cinc.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	Amit Singh Tomar <amittomer25@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-actions@...ts.infradead.org,
	Fedor Pchelkin <pchelkin@...ras.ru>,
	Alexey Khoroshilov <khoroshilov@...ras.ru>,
	Vadim Mutilin <mutilin@...ras.ru>,
	lvc-project@...uxtesting.org,
	stable@...r.kernel.org
Subject: [PATCH] tty: owl-uart: fix call balance of owl_port->clk handling routines

If owl_port->clk was enabled in owl_uart_probe(), it must be disabled in
all error paths to ensure proper cleanup. However, if uart_add_one_port()
returns an error in owl_uart_probe(), the owl_port->clk clock will not be
disabled.

Use the devm_clk_get_enabled() helper function to ensure proper call
balance for owl_port->clk.

Found by Linux Verification Center (linuxtesting.org) with Klever.

Fixes: abf42d2f333b ("tty: serial: owl: add "much needed" clk_prepare_enable()")
Cc: stable@...r.kernel.org
Signed-off-by: Vitalii Mordan <mordan@...ras.ru>
---
 drivers/tty/serial/owl-uart.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
index 0542882cfbbe..64446820437c 100644
--- a/drivers/tty/serial/owl-uart.c
+++ b/drivers/tty/serial/owl-uart.c
@@ -680,18 +680,12 @@ static int owl_uart_probe(struct platform_device *pdev)
 	if (!owl_port)
 		return -ENOMEM;
 
-	owl_port->clk = devm_clk_get(&pdev->dev, NULL);
+	owl_port->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(owl_port->clk)) {
-		dev_err(&pdev->dev, "could not get clk\n");
+		dev_err(&pdev->dev, "could not get and enable clk\n");
 		return PTR_ERR(owl_port->clk);
 	}
 
-	ret = clk_prepare_enable(owl_port->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "could not enable clk\n");
-		return ret;
-	}
-
 	owl_port->port.dev = &pdev->dev;
 	owl_port->port.line = pdev->id;
 	owl_port->port.type = PORT_OWL;
@@ -701,7 +695,6 @@ static int owl_uart_probe(struct platform_device *pdev)
 	owl_port->port.uartclk = clk_get_rate(owl_port->clk);
 	if (owl_port->port.uartclk == 0) {
 		dev_err(&pdev->dev, "clock rate is zero\n");
-		clk_disable_unprepare(owl_port->clk);
 		return -EINVAL;
 	}
 	owl_port->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP | UPF_LOW_LATENCY;
@@ -725,7 +718,6 @@ static void owl_uart_remove(struct platform_device *pdev)
 
 	uart_remove_one_port(&owl_uart_driver, &owl_port->port);
 	owl_uart_ports[pdev->id] = NULL;
-	clk_disable_unprepare(owl_port->clk);
 }
 
 static struct platform_driver owl_uart_platform_driver = {
-- 
2.25.1