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powerpc: Avoid comparison of unsigned long >= 0 in pfn_valid() 

Rewrite comparison since all values compared are of type `unsigned long`.

Instead of using unsigned properties and rewriting the original code as:
(originally suggested by Segher Boessenkool <segher@kernel.crashing.org>)

  #define pfn_valid(pfn) \
               (((pfn) - ARCH_PFN_OFFSET) < (max_mapnr - ARCH_PFN_OFFSET))

Prefer a static inline function to make code as readable as possible.

Fix a warning (treated as error in W=1):
  arch/powerpc/include/asm/page.h:129:32: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits]
  #define pfn_valid(pfn)  ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
                                  ^

Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Mathieu Malaterre 2018-03-07 21:34:35 +01:00 committed by Michael Ellerman
parent 4f1f40f7b2
commit 603b892200
1 changed files with 9 additions and 1 deletions
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10
arch/powerpc/include/asm/page.h
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@ -126,7 +126,15 @@ extern long long virt_phys_offset;
#ifdef CONFIG_FLATMEM
#define ARCH_PFN_OFFSET ((unsigned long)(MEMORY_START >> PAGE_SHIFT))
#define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
#ifndef __ASSEMBLY__
extern unsigned long max_mapnr;
static inline bool pfn_valid(unsigned long pfn)
{
unsigned long min_pfn = ARCH_PFN_OFFSET;
return pfn >= min_pfn && pfn < max_mapnr;
}
#endif
#endif
#define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT)