[PATCH] serial: lantiq: store and compare return status correctly

[PATCH] serial: lantiq: store and compare return status correctly

[Muhammad Usama Anjum]

platform_get_irq() returns signed status. It should be stored and
compared as signed value before storing to unsigned variable. Implicit
conversion from signed to unsigned and then comparison with less than
zero is wrong as unsigned value can never be less than zero.

Fixes: f087f01ca2 ("serial: lantiq: Use platform_get_irq() to get the interrupt")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 drivers/tty/serial/lantiq.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/lantiq.c b/drivers/tty/serial/lantiq.c
index bb059418cb82..3e324d3f0a6d 100644
--- a/drivers/tty/serial/lantiq.c
+++ b/drivers/tty/serial/lantiq.c
@@ -727,16 +727,20 @@ static int fetch_irq_lantiq(struct device *dev, struct ltq_uart_port *ltq_port)
 {
 	struct uart_port *port = &ltq_port->port;
 	struct platform_device *pdev = to_platform_device(dev);
-
-	ltq_port->tx_irq = platform_get_irq(pdev, 0);
-	if (ltq_port->tx_irq < 0)
-		return ltq_port->tx_irq;
-	ltq_port->rx_irq = platform_get_irq(pdev, 1);
-	if (ltq_port->rx_irq < 0)
-		return ltq_port->rx_irq;
-	ltq_port->err_irq = platform_get_irq(pdev, 2);
-	if (ltq_port->err_irq < 0)
-		return ltq_port->err_irq;
+	int irq;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+	ltq_port->tx_irq = irq;
+	irq = platform_get_irq(pdev, 1);
+	if (irq < 0)
+		return irq;
+	ltq_port->rx_irq = irq;
+	irq = platform_get_irq(pdev, 2);
+	if (irq < 0)
+		return irq;
+	ltq_port->err_irq = irq;
 
 	port->irq = ltq_port->tx_irq;
 
-- 
2.30.2

Re: [PATCH] serial: lantiq: store and compare return status correctly

[Rob Herring]

On Tue, Dec 21, 2021 at 2:42 PM Muhammad Usama Anjum
<usama.anjum@collabora.com> wrote:
>
> platform_get_irq() returns signed status. It should be stored and
> compared as signed value before storing to unsigned variable. Implicit
> conversion from signed to unsigned and then comparison with less than
> zero is wrong as unsigned value can never be less than zero.
>
> Fixes: f087f01ca2 ("serial: lantiq: Use platform_get_irq() to get the interrupt")
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---
>  drivers/tty/serial/lantiq.c | 24 ++++++++++++++----------
>  1 file changed, 14 insertions(+), 10 deletions(-)

Thanks for fixing this.

Acked-by: Rob Herring <robh@kernel.org>