linux-kernel - Re: [RFC PATCH 1/2] tty: serial/8250: Fix build warning in serial8250_probe

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Message-ID: <aJKDCjFyei1lRYxk@smile.fi.intel.com>
Date: Wed, 6 Aug 2025 01:17:46 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Abinash Singh <abinashsinghlalotra@...il.com>
Cc: gregkh@...uxfoundation.org, jirislaby@...nel.org,
	sunilvl@...tanamicro.com, arnd@...db.de,
	u.kleine-koenig@...libre.com, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] tty: serial/8250: Fix build warning in
 serial8250_probe_acpi()

On Wed, Aug 06, 2025 at 01:21:54AM +0530, Abinash Singh wrote:
> The function serial8250_probe_acpi() in 8250_platform.c triggered a
>     frame size warning:
> drivers/tty/serial/8250/8250_platform.c: In function ‘serial8250_probe_acpi’:
> drivers/tty/serial/8250/8250_platform.c:152:1: warning: the frame size of 1160 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> 
> This patch reduces the stack usage by dynamically allocating the
>     `uart` structure using kmalloc(), rather than placing it on
>     the stack. This eliminates the overflow warning and improves kernel
>     robustness.

...

>  #include <linux/platform_device.h>
> -

Stray change.

> +#include <linux/cleanup.h>

Please, keep it ordered.

>  #include <linux/serial_8250.h>

...

>  	struct device *dev = &pdev->dev;
> -	struct uart_8250_port uart = { };
> +	struct uart_8250_port *uart __free(kfree) = NULL;
>  	struct resource *regs;
>  	int ret, line;
>  
> +	uart = kmalloc(sizeof(*uart), GFP_KERNEL);

Just declare variable here, as the NULL assignment may lead to subtle issues.

> +	if (!uart)
> +		return -ENOMEM;

> +	memset(uart, 0, sizeof(*uart));

We have kzalloc() for this.


-- 
With Best Regards,
Andy Shevchenko