Re: [PATCH 4/4] dt-overlay: Support target-path being root node

[Michal Orzel <michal.orzel@xxxxxxx>]

On 20/09/2024 05:54, Stefano Stabellini wrote:
> 
> 
> On Thu, 19 Sep 2024, Michal Orzel wrote:
>> Even though in most cases device nodes are not present directly under
>> the root node, it's a perfectly valid configuration (e.g. Qemu virt
>> machine dtb). At the moment, we don't handle this scenario which leads
>> to unconditional addition of extra leading '/' in the node full path.
>> This makes the attempt to add such device overlay to fail.
>>
>> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
>> ---
>>  xen/common/dt-overlay.c | 16 +++++++++++-----
>>  1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/xen/common/dt-overlay.c b/xen/common/dt-overlay.c
>> index d18bd12bd38d..63b28889de90 100644
>> --- a/xen/common/dt-overlay.c
>> +++ b/xen/common/dt-overlay.c
>> @@ -325,6 +325,7 @@ static int overlay_get_nodes_info(const void *fdto, char 
>> **nodes_full_path)
>>              int node_name_len;
>>              unsigned int target_path_len = strlen(target_path);
>>              unsigned int node_full_name_len;
>> +            unsigned int extra_len;
>>
>>              node_name = fdt_get_name(fdto, subnode, &node_name_len);
>>
>> @@ -332,10 +333,13 @@ static int overlay_get_nodes_info(const void *fdto, 
>> char **nodes_full_path)
>>                  return node_name_len;
>>
>>              /*
>> -             * Magic number 2 is for adding '/' and '\0'. This is done to 
>> keep
>> -             * the node_full_path in the correct full node name format.
>> +             * Extra length is for adding '/' and '\0' unless the target 
>> path is
>> +             * root in which case we don't add the '/' at the beginning. 
>> This is
>> +             * done to keep the node_full_path in the correct full node name
>> +             * format.
>>               */
>> -            node_full_name_len = target_path_len + node_name_len + 2;
>> +            extra_len = (target_path_len > 1) + 1;
> 
> I'd prefer to avoid the implicit bool to int conversion. I think it is
> mandated by MISRA R10.1, we have a bool exception but I don't think it
> would cover this type of usage. For instance:
> 
> extra_len = ((target_path_len > 1) ? 1 : 0)  + 1;
> 
> or
> 
> extra_len = (target_path_len > 1) ? 2 : 1;
Ok, will do this version.

~Michal