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Commit ece86e22 authored by Jianyu Zhan's avatar Jianyu Zhan Committed by Linus Torvalds
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mm/vmalloc: interchage the implementation of vmalloc_to_{pfn,page} 



Currently we are implementing vmalloc_to_pfn() as a wrapper around
vmalloc_to_page(), which is implemented as follow:

 1. walks the page talbes to generates the corresponding pfn,
 2. then converts the pfn to struct page,
 3. returns it.

And vmalloc_to_pfn() re-wraps vmalloc_to_page() to get the pfn.

This seems too circuitous, so this patch reverses the way: implement
vmalloc_to_page() as a wrapper around vmalloc_to_pfn().  This makes
vmalloc_to_pfn() and vmalloc_to_page() slightly more efficient.

No functional change.

Signed-off-by: default avatarJianyu Zhan <nasa4836@gmail.com>
Cc: Vladimir Murzin <murzin.v@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d80be7c7

mm/vmalloc.c

+10 −10
Original line number Diff line number Diff line
@@ -220,12 +220,12 @@ int is_vmalloc_or_module_addr(const void *x) 
}



/*

 * Walk a vmap address to the struct page it maps.

 * Walk a vmap address to the physical pfn it maps to.

 */

struct page *vmalloc_to_page(const void *vmalloc_addr)

unsigned long vmalloc_to_pfn(const void *vmalloc_addr)

{

	unsigned long addr = (unsigned long) vmalloc_addr;

	struct page *page = NULL;

	unsigned long pfn = 0;

	pgd_t *pgd = pgd_offset_k(addr);



	/*
@@ -244,23 +244,23 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) 
				ptep = pte_offset_map(pmd, addr);

				pte = *ptep;

				if (pte_present(pte))

					page = pte_page(pte);

					pfn = pte_pfn(pte);

				pte_unmap(ptep);

			}

		}

	}

	return page;

	return pfn;

}

EXPORT_SYMBOL(vmalloc_to_page);

EXPORT_SYMBOL(vmalloc_to_pfn);



/*

 * Map a vmalloc()-space virtual address to the physical page frame number.

 * Map a vmalloc()-space virtual address to the struct page.

 */

unsigned long vmalloc_to_pfn(const void *vmalloc_addr)

struct page *vmalloc_to_page(const void *vmalloc_addr)

{

	return page_to_pfn(vmalloc_to_page(vmalloc_addr));

	return pfn_to_page(vmalloc_to_pfn(vmalloc_addr));

}

EXPORT_SYMBOL(vmalloc_to_pfn);

EXPORT_SYMBOL(vmalloc_to_page);





/*** Global kva allocator ***/