linux-kernel - Re: [PATCH 2/2] gpiolib: use kstrdup_const() for gpio

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Date:   Wed, 13 Dec 2017 11:44:39 -0800
From:   Joe Perches <joe@...ches.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] gpiolib: use kstrdup_const() for gpio_device label

On Wed, 2017-12-13 at 12:25 +0100, Bartosz Golaszewski wrote:
> Users often pass a pointer to a static string to gpiochip_add_data()
> family of functions. Avoid unnecessary memory allocations with the
> provided helper routine.
[]
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
[]
> @@ -1171,9 +1171,9 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
>  	}
>  
>  	if (chip->label)
> -		gdev->label = kstrdup(chip->label, GFP_KERNEL);
> +		gdev->label = kstrdup_const(chip->label, GFP_KERNEL);
>  	else
> -		gdev->label = kstrdup("unknown", GFP_KERNEL);
> +		gdev->label = kstrdup_const("unknown", GFP_KERNEL);

A plain ?: would be more intelligible
and a bit smaller object code too.

ie:
	gdev->label = kstrdup_const(chip->label ?: "unknown", GFP_KERNEL);

>  	if (!gdev->label) {
>  		status = -ENOMEM;
>  		goto err_free_descs;