Re: [PATCH 3/3] OF: base: add empty property value pointer

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, Jun 21, 2013 at 05:15:18PM +0200, Sebastian Hesselbarth wrote:
> Since property values can be empty, we need property value pointer to
> be non-NULL to distinguish those properties from non-existing properties.
> This adds a static u32 to which empty properties set their value pointer.
> Also, the value memory is only freed, if property length is not zero.
> 
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
> ---
> Cc: barebox@lists.infradead.org
> ---
>  drivers/of/base.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 7926d5d..a100a17 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1501,6 +1501,8 @@ struct device_node *of_new_node(struct device_node *parent, const char *name)
>  	return node;
>  }
>  
> +static u32 empty_prop_value;
> +
>  struct property *of_new_property(struct device_node *node, const char *name,
>  		const void *data, int len)
>  {
> @@ -1515,6 +1517,7 @@ struct property *of_new_property(struct device_node *node, const char *name,
>  		goto bail_out;
>  
>  	prop->length = len;
> +	prop->value = &empty_prop_value;

This at least breaks of_set_property() and of_free(). Both unconditionally
do a free(pp->value).

Why do we need this anyway? We can always call of_find_property() to see
if a property exists.

Sascha

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