* [PATCH] mm/slob: avoid type warning about alignment value
@ 2012-07-10 20:55 Arnd Bergmann
2012-07-11 1:18 ` David Rientjes
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2012-07-10 20:55 UTC (permalink / raw)
To: Pekka Enberg
Cc: Christoph Lameter, linux-kernel@vger.kernel.org, Matt Mackall,
linux-mm
The types for ARCH_KMALLOC_MINALIGN and ARCH_SLAB_MINALIGN are not always
the same, as seen by building ARM collie_defconfig:
mm/slob.c: In function 'kfree':
mm/slob.c:482:153: warning: comparison of distinct pointer types lacks a cast
mm/slob.c: In function 'ksize':
mm/slob.c:501:153: warning: comparison of distinct pointer types lacks a cast
Using max_t to find the correct alignment avoids the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
diff --git a/mm/slob.c b/mm/slob.c
index 95d1c7d..51d6a27 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -426,7 +426,7 @@ out:
void *__kmalloc_node(size_t size, gfp_t gfp, int node)
{
unsigned int *m;
- int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+ int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
void *ret;
gfp &= gfp_allowed_mask;
@@ -479,7 +479,7 @@ void kfree(const void *block)
sp = virt_to_page(block);
if (PageSlab(sp)) {
- int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+ int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
unsigned int *m = (unsigned int *)(block - align);
slob_free(m, *m + align);
} else
@@ -498,7 +498,7 @@ size_t ksize(const void *block)
sp = virt_to_page(block);
if (PageSlab(sp)) {
- int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+ int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
unsigned int *m = (unsigned int *)(block - align);
return SLOB_UNITS(*m) * SLOB_UNIT;
} else
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] mm/slob: avoid type warning about alignment value
2012-07-10 20:55 [PATCH] mm/slob: avoid type warning about alignment value Arnd Bergmann
@ 2012-07-11 1:18 ` David Rientjes
2012-07-11 6:39 ` Arnd Bergmann
0 siblings, 1 reply; 4+ messages in thread
From: David Rientjes @ 2012-07-11 1:18 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Pekka Enberg, Christoph Lameter, linux-kernel@vger.kernel.org,
Matt Mackall, linux-mm
On Tue, 10 Jul 2012, Arnd Bergmann wrote:
> diff --git a/mm/slob.c b/mm/slob.c
> index 95d1c7d..51d6a27 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -426,7 +426,7 @@ out:
> void *__kmalloc_node(size_t size, gfp_t gfp, int node)
> {
> unsigned int *m;
> - int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> + int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> void *ret;
>
> gfp &= gfp_allowed_mask;
> @@ -479,7 +479,7 @@ void kfree(const void *block)
>
> sp = virt_to_page(block);
> if (PageSlab(sp)) {
> - int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> + int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> unsigned int *m = (unsigned int *)(block - align);
> slob_free(m, *m + align);
> } else
> @@ -498,7 +498,7 @@ size_t ksize(const void *block)
>
> sp = virt_to_page(block);
> if (PageSlab(sp)) {
> - int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> + int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
> unsigned int *m = (unsigned int *)(block - align);
> return SLOB_UNITS(*m) * SLOB_UNIT;
> } else
Wouldn't it be better to avoid this problem more generally by casting the
__alignof__ for ARCH_{KMALLOC,SLAB}_MINALIGN to int in slab.h? All
architectures that define these themselves will be using plain integers,
the problem is __alignof__ returning size_t when undefined.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm/slob: avoid type warning about alignment value
2012-07-11 1:18 ` David Rientjes
@ 2012-07-11 6:39 ` Arnd Bergmann
2012-07-11 20:42 ` David Rientjes
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2012-07-11 6:39 UTC (permalink / raw)
To: David Rientjes
Cc: Pekka Enberg, Christoph Lameter, linux-kernel@vger.kernel.org,
Matt Mackall, linux-mm
On Wednesday 11 July 2012, David Rientjes wrote:
> Wouldn't it be better to avoid this problem more generally by casting the
> __alignof__ for ARCH_{KMALLOC,SLAB}_MINALIGN to int in slab.h? All
> architectures that define these themselves will be using plain integers,
> the problem is __alignof__ returning size_t when undefined.
I thought about it but I wasn't sure if that would cover all possible
cases. My version at least is known not to introduce a different type
mismatch on another architecture.
Also, size_t seems to be the correct type here, while the untyped
definition is just an int.
Arnd
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm/slob: avoid type warning about alignment value
2012-07-11 6:39 ` Arnd Bergmann
@ 2012-07-11 20:42 ` David Rientjes
0 siblings, 0 replies; 4+ messages in thread
From: David Rientjes @ 2012-07-11 20:42 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Pekka Enberg, Christoph Lameter, linux-kernel, Matt Mackall,
linux-mm
On Wed, 11 Jul 2012, Arnd Bergmann wrote:
> Also, size_t seems to be the correct type here, while the untyped
> definition is just an int.
>
Ok, sounds good, thanks.
Acked-by: David Rientjes <rientjes@google.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-07-10 20:55 [PATCH] mm/slob: avoid type warning about alignment value Arnd Bergmann
2012-07-11 1:18 ` David Rientjes
2012-07-11 6:39 ` Arnd Bergmann
2012-07-11 20:42 ` David Rientjes
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