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[v2,05/21] powerpc: Avoid comparison of unsigned long >= 0 in pfn_valid

Message ID 20180307203436.23696-1-malat@debian.org (mailing list archive)
State Accepted
Commit 603b892200e653dd7e86a0e4a315561534d97441
Headers show
Series None | expand

Commit Message

Mathieu Malaterre March 7, 2018, 8:34 p.m. UTC 
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):

  CC      arch/powerpc/kernel/irq.o
In file included from ./include/linux/bug.h:5:0,
                 from ./include/linux/cpumask.h:13,
                 from ./include/linux/smp.h:13,
                 from ./include/linux/kernel_stat.h:5,
                 from arch/powerpc/kernel/irq.c:35:
./include/linux/dma-mapping.h: In function ‘dma_map_resource’:
./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>
---
 arch/powerpc/include/asm/page.h | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

Comments

Michael Ellerman March 14, 2018, 9:28 a.m. UTC | #1 
On Wed, 2018-03-07 at 20:34:35 UTC, Mathieu Malaterre wrote:
> 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):
> 
>   CC      arch/powerpc/kernel/irq.o
> In file included from ./include/linux/bug.h:5:0,
>                  from ./include/linux/cpumask.h:13,
>                  from ./include/linux/smp.h:13,
>                  from ./include/linux/kernel_stat.h:5,
>                  from arch/powerpc/kernel/irq.c:35:
> ./include/linux/dma-mapping.h: In function ‘dma_map_resource’:
> ./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>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/603b892200e653dd7e86a0e4a31556

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 8da5d4c1cab2..6f74938483b7 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -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)