Re: [RFC PATCH v3 3/9] software_node: Fix failure to hold refcount in software_node_get_next_child

[Dan Scally]

Hi Sakari

On 20/10/2020 14:31, Sakari Ailus wrote:
> Hi Daniel,
>
> On Mon, Oct 19, 2020 at 11:58:57PM +0100, Daniel Scally wrote:
>> The software_node_get_next_child() function currently does not hold a kref
>> to the child software_node; fix that.
>>
>> Fixes: 59abd83672f7 ("drivers: base: Introducing software nodes to the firmware node framework")
>> Signed-off-by: Daniel Scally <djrscally@xxxxxxxxx>
>> ---
>> Changes in v3:
>> 	- split out from the full software_node_graph*() patch
>>
>>  drivers/base/swnode.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
>> index f01b1cc61..741149b90 100644
>> --- a/drivers/base/swnode.c
>> +++ b/drivers/base/swnode.c
>> @@ -450,7 +450,7 @@ software_node_get_next_child(const struct fwnode_handle *fwnode,
>>  		c = list_next_entry(c, entry);
>>  	else
>>  		c = list_first_entry(&p->children, struct swnode, entry);
>> -	return &c->fwnode;
>> +	return software_node_get(&c->fwnode);
> I believe similarly, the function should drop the reference to the previous
> node, and not expect the caller to do this. The OF equivalent does the
> same.

I think I prefer it this way myself, since the alternative is having to
explicitly call *_node_get() on a returned child if you want to keep it
but also keep iterating. But I agree that it's important to take a
consistent approach. I'll add that too; this will mean
swnode_graph_find_next_port() and
software_node_graph_get_next_endpoint() in patch 4 of this series will
need changing slightly to square away their references.