Subject: Re: [PATCH 11/15] memblock: reduce number of parameters in for_each_mem_range()

From: Baoquan He <[email-masked]>
Date: Thu, 30 Jul 2020 10:22:09 +0800

On 07/28/20 at 08:11am, Mike Rapoport wrote:
> From: Mike Rapoport <[email-masked]>
> 
> Currently for_each_mem_range() iterator is the most generic way to traverse
> memblock regions. As such, it has 8 parameters and it is hardly convenient
> to users. Most users choose to utilize one of its wrappers and the only
> user that actually needs most of the parameters outside memblock is s390
> crash dump implementation.
> 
> To avoid yet another naming for memblock iterators, rename the existing
> for_each_mem_range() to __for_each_mem_range() and add a new
> for_each_mem_range() wrapper with only index, start and end parameters.
> 
> The new wrapper nicely fits into init_unavailable_mem() and will be used in
> upcoming changes to simplify memblock traversals.
> 
> Signed-off-by: Mike Rapoport <[email-masked]>
> ---
>  .clang-format                          |  1 +
>  arch/arm64/kernel/machine_kexec_file.c |  6 ++----
>  arch/s390/kernel/crash_dump.c          |  8 ++++----
>  include/linux/memblock.h               | 18 ++++++++++++++----
>  mm/page_alloc.c                        |  3 +--
>  5 files changed, 22 insertions(+), 14 deletions(-)

Reviewed-by: Baoquan He <[email-masked]>

> 
> diff --git a/.clang-format b/.clang-format
> index a0a96088c74f..52ededab25ce 100644
> --- a/.clang-format
> +++ b/.clang-format
> @@ -205,6 +205,7 @@ ForEachMacros:
>    - 'for_each_memblock_type'
>    - 'for_each_memcg_cache_index'
>    - 'for_each_mem_pfn_range'
> +  - '__for_each_mem_range'
>    - 'for_each_mem_range'
>    - 'for_each_mem_range_rev'
>    - 'for_each_migratetype_order'
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index 361a1143e09e..5b0e67b93cdc 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -215,8 +215,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  	phys_addr_t start, end;
>  
>  	nr_ranges = 1; /* for exclusion of crashkernel region */
> -	for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
> -					MEMBLOCK_NONE, &start, &end, NULL)
> +	for_each_mem_range(i, &start, &end)
>  		nr_ranges++;
>  
>  	cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
> @@ -225,8 +224,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  
>  	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
> -	for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
> -					MEMBLOCK_NONE, &start, &end, NULL) {
> +	for_each_mem_range(i, &start, &end) {
>  		cmem->ranges[cmem->nr_ranges].start = start;
>  		cmem->ranges[cmem->nr_ranges].end = end - 1;
>  		cmem->nr_ranges++;
> diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
> index f96a5857bbfd..e28085c725ff 100644
> --- a/arch/s390/kernel/crash_dump.c
> +++ b/arch/s390/kernel/crash_dump.c
> @@ -549,8 +549,8 @@ static int get_mem_chunk_cnt(void)
>  	int cnt = 0;
>  	u64 idx;
>  
> -	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> -			   MEMBLOCK_NONE, NULL, NULL, NULL)
> +	__for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> +			     MEMBLOCK_NONE, NULL, NULL, NULL)
>  		cnt++;
>  	return cnt;
>  }
> @@ -563,8 +563,8 @@ static void loads_init(Elf64_Phdr *phdr, u64 loads_offset)
>  	phys_addr_t start, end;
>  	u64 idx;
>  
> -	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> -			   MEMBLOCK_NONE, &start, &end, NULL) {
> +	__for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> +			     MEMBLOCK_NONE, &start, &end, NULL) {
>  		phdr->p_filesz = end - start;
>  		phdr->p_type = PT_LOAD;
>  		phdr->p_offset = start;
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index e6a23b3db696..d70c2835e913 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -142,7 +142,7 @@ void __next_reserved_mem_region(u64 *idx, phys_addr_t *out_start,
>  void __memblock_free_late(phys_addr_t base, phys_addr_t size);
>  
>  /**
> - * for_each_mem_range - iterate through memblock areas from type_a and not
> + * __for_each_mem_range - iterate through memblock areas from type_a and not
>   * included in type_b. Or just type_a if type_b is NULL.
>   * @i: u64 used as loop variable
>   * @type_a: ptr to memblock_type to iterate
> @@ -153,7 +153,7 @@ void __memblock_free_late(phys_addr_t base, phys_addr_t size);
>   * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
>   * @p_nid: ptr to int for nid of the range, can be %NULL
>   */
> -#define for_each_mem_range(i, type_a, type_b, nid, flags,		\
> +#define __for_each_mem_range(i, type_a, type_b, nid, flags,		\
>  			   p_start, p_end, p_nid)			\
>  	for (i = 0, __next_mem_range(&i, nid, flags, type_a, type_b,	\
>  				     p_start, p_end, p_nid);		\
> @@ -182,6 +182,16 @@ void __memblock_free_late(phys_addr_t base, phys_addr_t size);
>  	     __next_mem_range_rev(&i, nid, flags, type_a, type_b,	\
>  				  p_start, p_end, p_nid))
>  
> +/**
> + * for_each_mem_range - iterate through memory areas.
> + * @i: u64 used as loop variable
> + * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
> + * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
> + */
> +#define for_each_mem_range(i, p_start, p_end) \
> +	__for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,	\
> +			     MEMBLOCK_NONE, p_start, p_end, NULL)
> +
>  /**
>   * for_each_reserved_mem_region - iterate over all reserved memblock areas
>   * @i: u64 used as loop variable
> @@ -287,8 +297,8 @@ int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask);
>   * soon as memblock is initialized.
>   */
>  #define for_each_free_mem_range(i, nid, flags, p_start, p_end, p_nid)	\
> -	for_each_mem_range(i, &memblock.memory, &memblock.reserved,	\
> -			   nid, flags, p_start, p_end, p_nid)
> +	__for_each_mem_range(i, &memblock.memory, &memblock.reserved,	\
> +			     nid, flags, p_start, p_end, p_nid)
>  
>  /**
>   * for_each_free_mem_range_reverse - rev-iterate through free memblock areas
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e028b87ce294..95af111d69d3 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6972,8 +6972,7 @@ static void __init init_unavailable_mem(void)
>  	 * Loop through unavailable ranges not covered by memblock.memory.
>  	 */
>  	pgcnt = 0;
> -	for_each_mem_range(i, &memblock.memory, NULL,
> -			NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL) {
> +	for_each_mem_range(i, &start, &end) {
>  		if (next < start)
>  			pgcnt += init_unavailable_range(PFN_DOWN(next),
>  							PFN_UP(start));
> -- 
> 2.26.2
> 
> 

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