Re: [PATCH 1/2] drivers/base/memory: Simplify add_boot_memory_block()

[Gavin Shan]

On 2/15/25 8:57 AM, Andrew Morton wrote:
> On Fri, 14 Feb 2025 16:35:03 +1000 Gavin Shan <gshan@xxxxxxxxxx> wrote:
>
> > It's unnecessary to keep the variable @section_count in the function
> > because the device for the specific memory block will be added if
> > any of its memory section is present. The variable @section_count
> > records the number of present memory sections in the specific memory
> > block, which isn't needed.
> >
> > Simplify the function by dropping the variable @section_count. No
> > functional change intended.
> >
> > ...
> >
> >   static int __init add_boot_memory_block(unsigned long base_section_nr)
> >   {
> > -	int section_count = 0;
> >   	unsigned long nr;
> >   
> >   	for (nr = base_section_nr; nr < base_section_nr + sections_per_block;
>
> mm/sparse.c has a for_each_present_section_nr() - is that usable here?

It should be fine to use it. I will add one preparatory patch to expose
for_each_present_section_nr(). With it, the nested if statements can also
be avoided, Something like below.

        for_each_present_section_nr(base_section_nr - 1, nr) {
		if (nr >= base_section_nr + sections_per_block)
			break;

		return add_memory_block(memory_block_id(nr), MEM_ONLINE, NULL, NULL);
        }

	return 0;

> > -	     nr++)
> > -		if (present_section_nr(nr))
> > -			section_count++;
> > +	     nr++) {
> > +		if (present_section_nr(nr)) {
> > +			return add_memory_block(memory_block_id(base_section_nr),
> > +						MEM_ONLINE, NULL, NULL);
> > +		}
> > +	}

Thanks,
Gavin