[PATCH] serial: vt8500: Fix clock reference leak in vt8500_serial_probe()

[PATCH] serial: vt8500: Fix clock reference leak in vt8500_serial_probe()

[Wentao Liang]

of_clk_get() returns a clock with a reference that has to be released
with clk_put(). If clk_prepare_enable() fails the function returns
without doing so, leaking the reference.

Add the missing clk_put() on that error path.

Fixes: 12faa35ae5cb ("serial: vt8500: UART uses gated clock rather than 24Mhz reference")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/tty/serial/vt8500_serial.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index 78a1c1eea11b..fc6fdc751b16 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -656,6 +656,7 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	ret = clk_prepare_enable(vt8500_port->clk);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to enable clock\n");
+		clk_put(vt8500_port->clk);
 		return ret;
 	}
 
-- 
2.34.1

Re: [PATCH] serial: vt8500: Fix clock reference leak in vt8500_serial_probe()

[Alexey Charkov]

On Thu, Sep 17, 2026 at 7:58 PM Wentao Liang <vulab@iscas.ac.cn> wrote:
>
> of_clk_get() returns a clock with a reference that has to be released
> with clk_put(). If clk_prepare_enable() fails the function returns
> without doing so, leaking the reference.
>
> Add the missing clk_put() on that error path.
>
> Fixes: 12faa35ae5cb ("serial: vt8500: UART uses gated clock rather than 24Mhz reference")
> Cc: stable@vger.kernel.org
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>  drivers/tty/serial/vt8500_serial.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
> index 78a1c1eea11b..fc6fdc751b16 100644
> --- a/drivers/tty/serial/vt8500_serial.c
> +++ b/drivers/tty/serial/vt8500_serial.c
> @@ -656,6 +656,7 @@ static int vt8500_serial_probe(struct platform_device *pdev)
>         ret = clk_prepare_enable(vt8500_port->clk);
>         if (ret) {
>                 dev_err(&pdev->dev, "failed to enable clock\n");
> +               clk_put(vt8500_port->clk);

The probe function currently mixes devm-managed and manual resource
allocations, with the clk standing out in particular. Instead of
adding a manual clk_put, could you please switch the clk calls to
devm_clk_get_enabled and drop redundant boilerplate?

Best regards,
Alexey

[PATCH] serial: vt8500: Use devm_clk_get_enabled()

[Wentao Liang]

Hi Alexey,

Sorry for the very late reply. Working through the review comments I got
in September has taken me far longer than it should have.

Your suggestion was right, but the leak fix went in before I could act on
it: it is commit 9d8955281d92 ("serial: vt8500: Fix clock reference leak
in vt8500_serial_probe()") in mainline, and it kept the clk_put() you
asked me to replace. It has been backported to the stable trees by now as
well. So the patch below is not a v2 of that one, which would only resend
something that is already applied, but a follow-up that does the
conversion on top of it.

devm_clk_get_enabled() gets the clock and enables it in one call and
registers the disable and put with devm, so both the manual error handling
and the clk_put() go away. Probe now returns the error code from the clock
lookup instead of a hard-coded -EINVAL, and the clock is released
automatically through devres. The success path is unchanged and nothing
else in the driver is touched.

For the record on where this came from: the candidate came from our static
analysis tooling, and DeepSeek and GPT-6.1 Sol were used to audit it and to
help write the change. I reviewed the result and I am responsible for it.
The patch is build-tested only: it compiles cleanly with W=1 for arm
(vt8500_v6_v7_defconfig, CONFIG_SERIAL_VT8500=y) and passes
checkpatch.pl --strict; I have no VT8500 hardware to test it on.

Thanks for the review,
Wentao

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Wentao Liang <vulab@iscas.ac.cn>
Date: Sun, 8 Nov 2026 11:41:30 +0000
Subject: [PATCH] serial: vt8500: Use devm_clk_get_enabled()

vt8500_serial_probe() gets the clock with of_clk_get() and enables it
with clk_prepare_enable(), so the reference has to be dropped by hand on
the error path, and the clock is never disabled or released afterwards,
even though the rest of the probe is devm-managed.

Use devm_clk_get_enabled() instead, which gets and enables the clock in
one call and registers the teardown with devm. The manual error handling
and the clk_put() can then go, and probe returns the actual error code
from the clock lookup rather than a hard-coded -EINVAL.

The clock still stays enabled as long as the port is in use, so the
success path is unchanged.
---
 drivers/tty/serial/vt8500_serial.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c
index fc6fdc751b16..73922523dff6 100644
--- a/drivers/tty/serial/vt8500_serial.c
+++ b/drivers/tty/serial/vt8500_serial.c
@@ -603,7 +603,6 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	struct resource *mmres;
 	struct device_node *np = pdev->dev.of_node;
 	const unsigned int *flags;
-	int ret;
 	int port;
 	int irq;
 
@@ -647,17 +646,10 @@ static int vt8500_serial_probe(struct platform_device *pdev)
 	if (IS_ERR(vt8500_port->uart.membase))
 		return PTR_ERR(vt8500_port->uart.membase);
 
-	vt8500_port->clk = of_clk_get(pdev->dev.of_node, 0);
+	vt8500_port->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(vt8500_port->clk)) {
 		dev_err(&pdev->dev, "failed to get clock\n");
-		return  -EINVAL;
-	}
-
-	ret = clk_prepare_enable(vt8500_port->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to enable clock\n");
-		clk_put(vt8500_port->clk);
-		return ret;
+		return PTR_ERR(vt8500_port->clk);
 	}
 
 	vt8500_port->vt8500_uart_flags = *flags;
-- 
2.34.1