Re: [PATCH 2/3] mm: don't rely on system state to detect hot-plug operations

Laurent Dufour
2020-09-14T08:39:49Z

Le 14/09/2020 à 10:19, Oscar Salvador a écrit :
> On Mon, Sep 14, 2020 at 09:57:46AM +0200, David Hildenbrand wrote:
>>> /* register memory section under specified node if it spans that node */
>>> +struct rmsun_args {
>>> + int nid;
>>> + enum memplug_context context;
>>> +};
>
> Uhmf, that is a not so descriptive name.

I do agree, but didn't have a better idea.
Anyway this will disappear since the choosen direction is to have 2 callbacks.

>
>> Instead of handling this in register_mem_sect_under_node(), I
>> think it would be better two have two separate
>> register_mem_sect_under_node() implementations.
>>
>> static int register_mem_sect_under_node_hotplug(struct memory_block *mem_blk,
>> void *arg)
>> {
>> const int nid = *(int *)arg;
>> int ret;
>>
>> /* Hotplugged memory has no holes and belongs to a single node. */
>> mem_blk->nid = nid;
>> ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
>> &mem_blk->dev.kobj,
>> kobject_name(&mem_blk->dev.kobj));
>> if (ret)
>> returnr et;
>> return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
>> &node_devices[nid]->dev.kobj,
>> kobject_name(&node_devices[nid]->dev.kobj));
>>
>> }
>>
>> Cleaner, right? :) No unnecessary checks.
>
> I tend to agree here, I like more a simplistic version for hotplug.
>
>> One could argue if link_mem_section_hotplug() would be better than passing around the context.
>
> I am not sure if I would duplicate the code there.
> We could just pass the pointer of the function we want to call to
> link_mem_sections? either register_mem_sect_under_node_hotplug or
> register_mem_sect_under_node_early?
> Would not that be clean and clear enough?

That would expose the register_mem_sect_under_node*() prototype to the caller.

I'm wondering if that would be cleaner than passing a MEMPLUG_* constant value
to link_mem_sections() and let it choose the right callback.