[PATCH] powerpc32: fix warning from include/linux/mm.h

[PATCH] powerpc32: fix warning from include/linux/mm.h

[Christophe Leroy]

include/linux/mm.h: In function 'is_vmalloc_addr':
include/linux/mm.h:367:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  return addr >= VMALLOC_START && addr < VMALLOC_END;
              ^

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

---
 arch/powerpc/include/asm/pgtable-ppc32.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index 234e07c..543bb8e 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -92,7 +92,7 @@ extern int icache_44x_need_flush;
  * system.  This really does become a problem for machines with good amounts
  * of RAM.  -- Cort
  */
-#define VMALLOC_OFFSET (0x1000000) /* 16M */
+#define VMALLOC_OFFSET (0x1000000U) /* 16M */
 #ifdef PPC_PIN_SIZE
 #define VMALLOC_START (((_ALIGN((long)high_memory, PPC_PIN_SIZE) + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
 #else
-- 
2.1.0

Re: powerpc32: fix warning from include/linux/mm.h

[Scott Wood]

On Fri, Dec 05, 2014 at 12:20:20PM +0100, LEROY Christophe wrote:
> include/linux/mm.h: In function 'is_vmalloc_addr':
> include/linux/mm.h:367:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
>   return addr >= VMALLOC_START && addr < VMALLOC_END;
>               ^
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>  arch/powerpc/include/asm/pgtable-ppc32.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

That warning doesn't appear to be enabled.  What config are you seeing
this with?

I'm also not clear on why this was assigned to me in patchwork.

-Scott

Re: powerpc32: fix warning from include/linux/mm.h

[leroy christophe]

Le 21/03/2015 00:52, Scott Wood a écrit :
> On Fri, Dec 05, 2014 at 12:20:20PM +0100, LEROY Christophe wrote:
>> include/linux/mm.h: In function 'is_vmalloc_addr':
>> include/linux/mm.h:367:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
>>    return addr >= VMALLOC_START && addr < VMALLOC_END;
>>                ^
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>>   arch/powerpc/include/asm/pgtable-ppc32.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> That warning doesn't appear to be enabled.  What config are you seeing
> this with?
I'm used to adding EXTRA_CFLAGS=-Wextra  when checking my own drivers, 
as it helps finding additional bugs.

When doing that, the only warnings I get outside of my own code are this 
one, and the other one in my proposed patch identified "powerpc32: fix 
warning from include/asm-generic/termios-base.h"

I though it would be worth fixing those two warnings in order to get a 
perfectly clean code.

Christophe

Re: powerpc32: fix warning from include/linux/mm.h

[Scott Wood]

On Tue, 2015-04-07 at 10:07 +0200, leroy christophe wrote:
> Le 21/03/2015 00:52, Scott Wood a écrit :
> > On Fri, Dec 05, 2014 at 12:20:20PM +0100, LEROY Christophe wrote:
> >> include/linux/mm.h: In function 'is_vmalloc_addr':
> >> include/linux/mm.h:367:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
> >>    return addr >= VMALLOC_START && addr < VMALLOC_END;
> >>                ^
> >>
> >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> >> ---
> >>   arch/powerpc/include/asm/pgtable-ppc32.h | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> > That warning doesn't appear to be enabled.  What config are you seeing
> > this with?
> I'm used to adding EXTRA_CFLAGS=-Wextra  when checking my own drivers, 
> as it helps finding additional bugs.

It also produces a lot of noise, which is why Linux doesn't enable it.
E.g. it enables useless "unused parameter" warnings all over the place.

> When doing that, the only warnings I get outside of my own code are this 
> one, and the other one in my proposed patch identified "powerpc32: fix 
> warning from include/asm-generic/termios-base.h"
> 
> I though it would be worth fixing those two warnings in order to get a 
> perfectly clean code.

In general I don't think we should clutter up the code with suppression
for warnings we don't enable, but in this case we do end up with a value
that would be negative if considered as signed.  Instead of changing
VMALLOC_OFFSET, though, I'd address it where the problem is actually
introduced -- which is casting high_memory to (long) rather than
(unsigned long) or (uintptr_t).

-Scott

Re: powerpc32: fix warning from include/linux/mm.h

[Michael Ellerman]

On Fri, 2015-03-20 at 18:52 -0500, Scott Wood wrote:
> On Fri, Dec 05, 2014 at 12:20:20PM +0100, LEROY Christophe wrote:
> > include/linux/mm.h: In function 'is_vmalloc_addr':
> > include/linux/mm.h:367:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
> >   return addr >= VMALLOC_START && addr < VMALLOC_END;
> >               ^
> > 
> > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> > ---
> >  arch/powerpc/include/asm/pgtable-ppc32.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> That warning doesn't appear to be enabled.  What config are you seeing
> this with?
> 
> I'm also not clear on why this was assigned to me in patchwork.

Because it's from Christophe.

cheers