Re: [PATCH v2 02/17] dma-contiguous: simplify cma_early_percent_memory()

Baoquan He
2020-08-05T03:50:47Z

On 08/02/20 at 07:35pm, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> The memory size calculation in cma_early_percent_memory() traverses
> memblock.memory rather than simply call memblock_phys_mem_size(). The
> comment in that function suggests that at some point there should have been
> call to memblock_analyze() before memblock_phys_mem_size() could be used.
> As of now, there is no memblock_analyze() at all and
> memblock_phys_mem_size() can be used as soon as cold-plug memory is
> registerd with memblock.
>
> Replace loop over memblock.memory with a call to memblock_phys_mem_size().
>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
> kernel/dma/contiguous.c | 11 +----------
> 1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 15bc5026c485..1992afd8ca7b 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -73,16 +73,7 @@ early_param("cma", early_cma);
>
> static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
> {
> - struct memblock_region *reg;
> - unsigned long total_pages = 0;
> -
> - /*
> - * We cannot use memblock_phys_mem_size() here, because
> - * memblock_analyze() has not been called yet.
> - */
> - for_each_memblock(memory, reg)
> - total_pages += memblock_region_memory_end_pfn(reg) -
> - memblock_region_memory_base_pfn(reg);
> + unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size());

Reviewed-by: Baoquan He <bhe@redhat.com>

>
> return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
> }
> --
> 2.26.2
>