linux-kernel - Re: [PATCH] drivers/of: Improve documentation on match string

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Message-ID: <20240911164311.GA775781-robh@kernel.org>
Date: Wed, 11 Sep 2024 11:43:11 -0500
From: Rob Herring <robh@...nel.org>
To: Miquel Sabaté Solà <mikisabate@...il.com>
Cc: saravanak@...gle.com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/of: Improve documentation on match string

On Tue, Sep 10, 2024 at 04:24:22PM +0200, Miquel Sabaté Solà wrote:
> The description of the function now explicitly states that it's
> an *exact* match for the given string (i.e. not a submatch). It also
> better states all the possible return values.
> 
> Moreover, this commit also makes sure that -ENODATA is returned if
> prop->length is zero, just like it's done in other functions such as
> 'of_property_read_string'.

'also' in a commit message is a sign this should be 2 commits. However, 
more below.

> 
> Signed-off-by: Miquel Sabaté Solà <mikisabate@...il.com>
> ---
>  drivers/of/property.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 164d77cb9445..1ff51d93178f 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -452,12 +452,17 @@ EXPORT_SYMBOL_GPL(of_property_read_string);
> 
>  /**
>   * of_property_match_string() - Find string in a list and return index
> - * @np: pointer to node containing string list property
> + * @np: pointer to the node containing the string list property
>   * @propname: string list property name
> - * @string: pointer to string to search for in string list
> + * @string: pointer to the string to search for in the string list
>   *
> - * This function searches a string list property and returns the index
> - * of a specific string value.
> + * Search for an exact match of string in a device node property which is a
> + * list of strings.
> + *
> + * Return: the index of the first occurrence of the string on success, -EINVAL
> + * if the property does not exist, -ENODATA if the property does not have a
> + * value, and -EILSEQ if the string is not null-terminated within the length of
> + * the property data.
>   */
>  int of_property_match_string(const struct device_node *np, const char *propname,
>  			     const char *string)
> @@ -469,7 +474,7 @@ int of_property_match_string(const struct device_node *np, const char *propname,
> 
>  	if (!prop)
>  		return -EINVAL;
> -	if (!prop->value)
> +	if (!prop->value || !prop->length)

This is redundant. If length is 0, then 'end' will be equal to p and 
we'll return -ENODATA.

>  		return -ENODATA;
> 
>  	p = prop->value;
> --
> 2.46.0
>