Re: [PATCH v2 1/2] memblock: drop for_each_memblock_type() and open code its users

[Pratyush Yadav]

On Fri, Sep 18 2026, Tarun Sahu wrote:

> for_each_memblock_type() always starts the iteration at index 0 and its
> body is a trivial 'for' loop, so it hides very little. It also gets in
> the way of iterating from an arbitrary index, which the next patch
> needs.
>
> Remove the macro and open code its three users: memblock_add_range(),
> memblock_isolate_range() and memblock_dump(). While at it, move the
> region pointer into the loop body scope.
>
> No functional change.
>
> Signed-off-by: Tarun Sahu <tarunsahu@xxxxxxxxxx>
> ---
>  mm/memblock.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 9ce86349a29f..5aae75d34dec 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -155,11 +155,6 @@ struct memblock_type physmem = {
>   */
>  static __refdata struct memblock_type *memblock_memory = &memblock.memory;
>  
> -#define for_each_memblock_type(i, memblock_type, rgn)			\
> -	for (i = 0, rgn = &memblock_type->regions[0];			\
> -	     i < memblock_type->cnt;					\
> -	     i++, rgn = &memblock_type->regions[i])
> -
>  #define memblock_dbg(fmt, ...)						\
>  	do {								\
>  		if (memblock_debug)					\
> @@ -651,7 +646,8 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
>  	base = obase;
>  	nr_new = 0;
>  
> -	for_each_memblock_type(idx, type, rgn) {
> +	for (idx = 0; idx < type->cnt; idx++) {
> +		rgn = &type->regions[idx];

Nit: this is really odd to read. You assign rgn and then declare rbase
and rend. Doesn't checkpatch complain?

Regardless, I reckon it would be a lot nicer to read of you move the
declaration of rgn into the loop. Same for the others below.

LGTM otherwise, so after fixing this up, feel free to add:

Reviewed-by: Pratyush Yadav <pratyush@xxxxxxxxxx>

>  		phys_addr_t rbase = rgn->base;
>  		phys_addr_t rend = rbase + rgn->size;
>  
> @@ -827,7 +823,8 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
>  		if (memblock_double_array(type, base, size) < 0)
>  			return -ENOMEM;
>  
> -	for_each_memblock_type(idx, type, rgn) {
> +	for (idx = 0; idx < type->cnt; idx++) {
> +		rgn = &type->regions[idx];
>  		phys_addr_t rbase = rgn->base;
>  		phys_addr_t rend = rbase + rgn->size;
>  
> @@ -2198,7 +2195,8 @@ static void __init_memblock memblock_dump(struct memblock_type *type)
>  
>  	pr_info(" %s.cnt  = 0x%lx\n", type->name, type->cnt);
>  
> -	for_each_memblock_type(idx, type, rgn) {
> +	for (idx = 0; idx < type->cnt; idx++) {
> +		rgn = &type->regions[idx];
>  		char nid_buf[32] = "";
>  
>  		base = rgn->base;

-- 
Regards,
Pratyush Yadav