From ece86e222db48d04bda218a2be70e384518bb08c Mon Sep 17 00:00:00 2001
From: Jianyu Zhan <nasa4836@gmail.com>
Date: Tue, 21 Jan 2014 15:49:12 -0800
Subject: [PATCH] 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>
---
mm/vmalloc.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 0fdf96803c5b5..e4f0db2a3eae5 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -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 ***/
--
2.39.5