Re: [PATCH 1/2] drivers/base/node: merge register_one_node() and register_node() to a single function.

Donet Tom
2025-09-25T13:21:21Z

On 9/25/25 2:24 PM, David Hildenbrand wrote:
> On 24.09.25 20:40, Donet Tom wrote:
>> register_one_node() and register_node() are small functions.
>> This patch merges them into a single function named register_node()
>> to improve code readability.
>>
>> No functional changes are introduced.
>>
>> Signed-off-by: Donet Tom <donettom@linux.ibm.com>
>> ---
>
> [...]
>
>>   /**
>>    * unregister_node - unregister a node device
>>    * @node: node going away
>> @@ -869,7 +842,13 @@ void
>> register_memory_blocks_under_node_hotplug(int nid, unsigned long
>> start_pfn,
>>   }
>>   #endif /* CONFIG_MEMORY_HOTPLUG */
>>   -int register_one_node(int nid)
>> +/*
>
> We can directly convert this to proper kernel doc by using /**
>
Sure I will add it.

>
>> + * register_node - Setup a sysfs device for a node.
>> + * @nid - Node number to use when creating the device.
>> + *
>> + * Initialize and register the node device.
>
> and briefly describing what the return value means
>
> "Returns 0 on success, ..."
>
Sure

>> + */
>> +int register_node(int nid)
>>   {
>>       int error;
>>       int cpu;
>> @@ -880,14 +859,23 @@ int register_one_node(int nid)
>>           return -ENOMEM;
>>         INIT_LIST_HEAD(&node->access_list);
>> -    node_devices[nid] = node;
>>   -    error = register_node(node_devices[nid], nid);
>> +    node->dev.id = nid;
>> +    node->dev.bus = &node_subsys;
>> +    node->dev.release = node_device_release;
>> +    node->dev.groups = node_dev_groups;
>> +
>> +    error = device_register(&node->dev);
>>       if (error) {
>> -        node_devices[nid] = NULL;
>
> Wondering why we did have this temporary setting of the node_devices[]
> in there. But I cannot immediately spot why it was required.

node_devices[] is used in many places to access node data.

In the previous code, immediately after allocating the node

structure, it was stored in node_devices[]. On error paths, we

were clearing the node structure entry from node_devices[].

With the new code, the node structure is now stored in node_devices[]

only after the device has been registered, and just before calling

register_cpu_under_node(), since node_devices[] is accessed inside

that function.

It is also used outside of node.c, in hugetlb_register_all_nodes() .

Do you think we could use a different mechanism instead of this?