linux-kernel - Re: [PATCH v2 06/12] software_node: Add support for fwnode

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Date:   Mon, 21 Dec 2020 10:01:50 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...ica.org, rjw@...ysocki.net,
        lenb@...nel.org, gregkh@...uxfoundation.org, yong.zhi@...el.com,
        bingbu.cao@...el.com, tian.shu.qiu@...el.com, mchehab@...nel.org,
        robert.moore@...el.com, erik.kaneda@...el.com, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk,
        laurent.pinchart+renesas@...asonboard.com,
        jacopo+renesas@...ndi.org, kieran.bingham+renesas@...asonboard.com,
        linus.walleij@...aro.org, heikki.krogerus@...ux.intel.com,
        kitakar@...il.com, jorhand@...ux.microsoft.com
Subject: Re: [PATCH v2 06/12] software_node: Add support for fwnode_graph*()
 family of functions

Hi Sakari - thanks for the reviews in previous emails

On 21/12/2020 09:34, Sakari Ailus wrote:
> Hi Daniel and Heikki,
>
> On Thu, Dec 17, 2020 at 11:43:31PM +0000, Daniel Scally wrote:
>
> +static struct fwnode_handle *
> +software_node_graph_get_port_parent(struct fwnode_handle *fwnode)
> +{
> +	struct swnode *swnode = to_swnode(fwnode);
> +	struct fwnode_handle *parent;
> +
> +	if (!strcmp(swnode->parent->node->name, "ports"))
> +		parent = &swnode->parent->parent->fwnode;
> +	else
> +		parent = &swnode->parent->fwnode;
> If you happen to call this function on a non-port node for whatever reason,
> you may end up accessing a pointer that's NULL, can't you?

Yes, actually.

> Instead I'd do
> something like:
>
> swnode = swnode->parent;
> if (swnode && !strcmp(swnode->node->name, "ports"))
> 	swnode = swnode->parent;
>
> return swnode ? software_node_get(&swnode->fwnode) : NULL;
>
> You can also drop parent as a by-product of this.
Yes ok, that looks good to me - thanks.
>> +
>> +	return software_node_get(parent);
>> +}
>> +
>> +static int
>> +software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
>> +				   struct fwnode_endpoint *endpoint)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	int ret;
>> +
>> +	ret = kstrtou32(swnode->parent->node->name + 5, 10, &endpoint->port);
>> +	if (ret)
>> +		return ret;
>> +
>> +	endpoint->id = swnode->id;
>> +	endpoint->local_fwnode = fwnode;
>> +
>> +	return 0;
>> +}
>> +
>>  static const struct fwnode_operations software_node_ops = {
>>  	.get = software_node_get,
>>  	.put = software_node_put,
>> @@ -551,7 +655,11 @@ static const struct fwnode_operations software_node_ops = {
>>  	.get_parent = software_node_get_parent,
>>  	.get_next_child_node = software_node_get_next_child,
>>  	.get_named_child_node = software_node_get_named_child_node,
>> -	.get_reference_args = software_node_get_reference_args
>> +	.get_reference_args = software_node_get_reference_args,
>> +	.graph_get_next_endpoint = software_node_graph_get_next_endpoint,
>> +	.graph_get_remote_endpoint = software_node_graph_get_remote_endpoint,
>> +	.graph_get_port_parent = software_node_graph_get_port_parent,
>> +	.graph_parse_endpoint = software_node_graph_parse_endpoint,
>>  };
>>  
>>  /* -------------------------------------------------------------------------- */