linux-kernel - Re: [PATCH 1/5] mm/util: add kstrdup

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Date:	Mon, 12 Jan 2015 09:13:48 -0800
From:	Joe Perches <joe@...ches.com>
To:	Andrzej Hajda <a.hajda@...sung.com>
Cc:	linux-mm@...ck.org, Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-kernel@...r.kernel.org, andi@...stfloor.org, andi@...as.de,
	Mike Turquette <mturquette@...aro.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/5] mm/util: add kstrdup_const

On Mon, 2015-01-12 at 10:18 +0100, Andrzej Hajda wrote:
> The patch adds alternative version of kstrdup which returns pointer
> to constant char array. The function checks if input string is in
> persistent and read-only memory section, if yes it returns the input string,
> otherwise it fallbacks to kstrdup.
> kstrdup_const is accompanied by kfree_const performing conditional memory
> deallocation of the string.

trivia:

> diff --git a/mm/util.c b/mm/util.c
[]
> +void kfree_const(const void *x)
> +{
> +	if (!is_kernel_rodata((unsigned long)x))
> +		kfree(x);
> +}
> +EXPORT_SYMBOL(kfree_const);
[]
> +const char *kstrdup_const(const char *s, gfp_t gfp)
> +{
> +	if (is_kernel_rodata((unsigned long)s))
> +		return s;
> +
> +	return kstrdup(s, gfp);
> +}
> +EXPORT_SYMBOL(kstrdup_const);

I think it'd be nicer if these used the same form
even if it's a vertical line or 2 longer

void kfree_const(const void *x)
{
	if (is_kernel_rodata((unsigned long)x))
		return;

	kfree(x);
}


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