linux-kernel - Re: [PATCH v3 5/5] OF: Introduce utility helper functions

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Message-ID: <527CA9F4.9080003@nsn.com>
Date:	Fri, 08 Nov 2013 10:08:04 +0100
From:	Alexander Sverdlin <alexander.sverdlin@....com>
To:	ext Pantelis Antoniou <panto@...oniou-consulting.com>,
	Grant Likely <grant.likely@...retlab.ca>
CC:	Rob Herring <robherring2@...il.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Matt Porter <matt.porter@...aro.org>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Alison Chaiken <Alison_Chaiken@...tor.com>,
	Dinh Nguyen <dinh.linux@...il.com>,
	Jan Lubbe <jluebbe@...net.de>, Michael Stickel <ms@...able.de>,
	Guenter Roeck <linux@...ck-us.net>,
	Dirk Behme <dirk.behme@...il.com>,
	Alan Tull <delicious.quinoa@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Michael Bohan <mbohan@...eaurora.org>,
	Ionut Nicu <ioan.nicu.ext@....com>,
	Michal Simek <monstr@...str.eu>,
	Matt Ranostay <mranostay@...il.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/5] OF: Introduce utility helper functions

Hello Pantelis,

On 07/11/13 21:17, ext Pantelis Antoniou wrote:
> Introduce helper functions for working with the live DT tree.
> 
> __of_free_property() frees a dynamically created property
> __of_free_tree() recursively frees a device node tree
> __of_copy_property() copies a property dynamically
> __of_create_empty_node() creates an empty node
> __of_find_node_by_full_name() finds the node with the full name
> and
> of_multi_prop_cmp() performs a multi property compare but without
> having to take locks.
> 
> Signed-off-by: Pantelis Antoniou <panto@...oniou-consulting.com>
> ---
>  drivers/of/Makefile |   2 +-
>  drivers/of/util.c   | 253 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of.h  |  59 ++++++++++++
>  3 files changed, 313 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/of/util.c
> 

...

> +struct property *__of_copy_property(const struct property *prop, gfp_t flags)
> +{
> +	struct property *propn;
> +
> +	propn = kzalloc(sizeof(*prop), flags);
> +	if (propn == NULL)
> +		return NULL;
> +
> +	propn->name = kstrdup(prop->name, flags);
> +	if (propn->name == NULL)
> +		goto err_fail_name;
> +
> +	if (prop->length > 0) {
        ^^^^^^^^^^^^^^^^^^^^^^^
As Ioan already mentioned, this is really a problem.
There is a bunch of places, where properties without values are used.
Like gpio-controller; ranges; interrupt-controller;
Refer, for example, to of_irq_map_raw() which checks
of_get_property(ipar, "interrupt-controller", NULL) != NULL
and some other occurrences of exactly same construct.
This will simply be broken for merged device-tree parts.

> +		propn->value = kmalloc(prop->length, flags);
> +		if (propn->value == NULL)
> +			goto err_fail_value;
> +		memcpy(propn->value, prop->value, prop->length);
> +		propn->length = prop->length;
> +	}
> +
> +	/* mark the property as dynamic */
> +	of_property_set_flag(propn, OF_DYNAMIC);
> +
> +	return propn;
> +
> +err_fail_value:
> +	kfree(propn->name);
> +err_fail_name:
> +	kfree(propn);
> +	return NULL;
> +}
> +

...

-- 
Best regards,
Alexander Sverdlin.
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