linux-kernel - Re: [PATCH] pinctrl: make a deep copy of pinmux map

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 29 Nov 2011 14:24:41 +0000
From:	Arnd Bergmann <arnd.bergmann@...aro.org>
To:	Linus Walleij <linus.walleij@...ricsson.com>
Cc:	linux-kernel@...r.kernel.org, Stephen Warren <swarren@...dia.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Barry Song <21cnbao@...il.com>,
	Shawn Guo <shawn.guo@...escale.com>,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Dong Aisheng <dong.aisheng@...aro.org>,
	Rajendra Nayak <rajendra.nayak@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] pinctrl: make a deep copy of pinmux map

On Tuesday 29 November 2011, Linus Walleij wrote:
> From: Linus Walleij <linus.walleij@...aro.org>
> 
> This makes a deep copy of the pinmux function map instead of
> keeping the copy supplied from the platform around. This makes
> it possible to tag the platforms map with __initdata as is also
> done as part of this patch.
> 
> Rationale: a certain target platform (PXA) has numerous
> pinmux maps, many of which will be lying around unused after
> boot in a multi-platform binary. Instead, deep-copy the one
> we're going to use and tag them all __initdata so they go away
> after boot.
> 
> Suggested-by: Arnd Bergmann <arnd.bergmann@...aro.org>
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>

Very nice!

>  /**
>   * pinmux_register_mappings() - register a set of pinmux mappings
> - * @maps: the pinmux mappings table to register
> + * @maps: the pinmux mappings table to register, this should be marked with
> + *	__initdata so it can be discarded after boot, this function will
> + *	perform a deep copy (including strings) for the mapping entries.
>   * @num_maps: the number of maps in the mapping table
>   *

Is it actually necessary to copy the strings? I always thought they
end up in the constant data section even if the data structure that
they are defined in is in initdata.

> +
> +	/* Allocate a deep copy of the map array */
> +	pinmux_maps = kzalloc(sizeof(struct pinmux_map) * num_maps,
> +			      GFP_KERNEL);

I guess it's easier to use kmemdup here. At least there is no
point in zeroing the array when the next step is to overwrite it.

	Arnd

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/