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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: Jianyu Zhan <nasa4836@gmail.com>
Cc: Vladimir Murzin <murzin.v@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jianyu Zhan 2014-01-21 15:49:12 -08:00 committed by Linus Torvalds
parent d80be7c751
commit ece86e222d
1 changed files with 14 additions and 14 deletions
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28
mm/vmalloc.c
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@ -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);
/*
@ -244,24 +244,24 @@ 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;
}
EXPORT_SYMBOL(vmalloc_to_page);
/*
* Map a vmalloc()-space virtual address to the physical page frame number.
*/
unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
{
return page_to_pfn(vmalloc_to_page(vmalloc_addr));
return pfn;
}
EXPORT_SYMBOL(vmalloc_to_pfn);
/*
* Map a vmalloc()-space virtual address to the struct page.
*/
struct page *vmalloc_to_page(const void *vmalloc_addr)
{
return pfn_to_page(vmalloc_to_pfn(vmalloc_addr));
}
EXPORT_SYMBOL(vmalloc_to_page);
/*** Global kva allocator ***/