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

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Message-ID: <66e2012b.df0a0220.1eb799.1e97@mx.google.com>
Date: Wed, 11 Sep 2024 22:44:21 +0200
From: Miquel Sabaté Solà <mikisabate@...il.com>
To: Rob Herring <robh@...nel.org>
Cc: saravanak@...gle.com,  devicetree@...r.kernel.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/of: Improve documentation on match string

On dc., de set. 11 2024, Rob Herring wrote:

> 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.
>

Yikes, I missed it... You are totally right, sorry about that.

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

Thanks for the review. I will submit a new version of the patch just
with the documentation part.

Thanks!
Miquel

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