linux-kernel - Re: [PATCH v2 2/2] driver/base: Remove unused functions

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Message-ID: <0EBDDF27-E05A-43D2-834D-987D6228A516@nvidia.com>
Date: Thu, 01 May 2025 11:08:22 -0400
From: Zi Yan <ziy@...dia.com>
To: Donet Tom <donettom@...ux.ibm.com>
Cc: Mike Rapoport <rppt@...nel.org>, David Hildenbrand <david@...hat.com>,
 Oscar Salvador <osalvador@...e.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Andrew Morton <akpm@...ux-foundation.org>, rafael@...nel.org,
 Danilo Krummrich <dakr@...nel.org>, Ritesh Harjani <ritesh.list@...il.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Alison Schofield <alison.schofield@...el.com>,
 Yury Norov <yury.norov@...il.com>, Dave Jiang <dave.jiang@...el.com>,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] driver/base: Remove unused functions

On 28 Apr 2025, at 13:03, Donet Tom wrote:

> The functions register_mem_block_under_node_early and get_nid_for_pfn
> are not used, as register_memory_blocks_under_node_early is now used
> to register memory blocks during early boot. Therefore, these unused
> functions have been removed.
>
> Signed-off-by: Donet Tom <donettom@...ux.ibm.com>
> ---
>  drivers/base/node.c | 54 +--------------------------------------------
>  1 file changed, 1 insertion(+), 53 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 4869333d366d..59ec507fc97d 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -748,15 +748,6 @@ int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
>  }
>
>  #ifdef CONFIG_MEMORY_HOTPLUG
> -static int __ref get_nid_for_pfn(unsigned long pfn)
> -{
> -#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
> -	if (system_state < SYSTEM_RUNNING)
> -		return early_pfn_to_nid(pfn);
> -#endif
> -	return pfn_to_nid(pfn);
> -}
> -
>  static void do_register_memory_block_under_node(int nid,
>  						struct memory_block *mem_blk,
>  						enum meminit_context context)
> @@ -783,46 +774,6 @@ static void do_register_memory_block_under_node(int nid,
>  				    ret);
>  }
>
> -/* register memory section under specified node if it spans that node */
> -static int register_mem_block_under_node_early(struct memory_block *mem_blk,
> -					       void *arg)
> -{
> -	unsigned long memory_block_pfns = memory_block_size_bytes() / PAGE_SIZE;
> -	unsigned long start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
> -	unsigned long end_pfn = start_pfn + memory_block_pfns - 1;
> -	int nid = *(int *)arg;
> -	unsigned long pfn;
> -
> -	for (pfn = start_pfn; pfn <= end_pfn; pfn++) {
> -		int page_nid;
> -
> -		/*
> -		 * memory block could have several absent sections from start.
> -		 * skip pfn range from absent section
> -		 */
> -		if (!pfn_in_present_section(pfn)) {
> -			pfn = round_down(pfn + PAGES_PER_SECTION,
> -					 PAGES_PER_SECTION) - 1;
> -			continue;
> -		}
> -
> -		/*
> -		 * We need to check if page belongs to nid only at the boot
> -		 * case because node's ranges can be interleaved.
> -		 */
> -		page_nid = get_nid_for_pfn(pfn);
> -		if (page_nid < 0)
> -			continue;
> -		if (page_nid != nid)
> -			continue;
> -
> -		do_register_memory_block_under_node(nid, mem_blk, MEMINIT_EARLY);
> -		return 0;
> -	}
> -	/* mem section does not span the specified node */
> -	return 0;
> -}
> -
>  /*
>   * During hotplug we know that all pages in the memory block belong to the same
>   * node.
> @@ -895,10 +846,7 @@ void register_memory_blocks_under_node(int nid, unsigned long start_pfn,
>  {

Should this function be renamed to register_memory_blocks_under_node_hotplug
to reflect its current implementation?

>  	walk_memory_blocks_func_t func;
>
> -	if (context == MEMINIT_HOTPLUG)
> -		func = register_mem_block_under_node_hotplug;
> -	else
> -		func = register_mem_block_under_node_early;
> +	func = register_mem_block_under_node_hotplug;
>
>  	walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn),
>  			   (void *)&nid, func);
> -- 
> 2.48.1


--
Best Regards,
Yan, Zi