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| author | Joonsoo Kim <iamjoonsoo.kim@lge.com> | 2014-03-12 17:06:19 +0900 |
|---|---|---|
| committer | Pekka Enberg <penberg@kernel.org> | 2014-04-01 13:38:04 +0300 |
| commit | 24f870d8f0adcd38639f2f66e37aa7591a3fc408 (patch) | |
| tree | be36bd3e209e78faff043fda65337749b3bee7dc /include/linux/slab.h | |
| parent | 80c3a9981a544b6e96debfbcca5190b727ecd09e (diff) | |
| download | lwn-24f870d8f0adcd38639f2f66e37aa7591a3fc408.tar.gz lwn-24f870d8f0adcd38639f2f66e37aa7591a3fc408.zip | |
slab: fix wrongly used macro
commit 'slab: restrict the number of objects in a slab' uses
__builtin_constant_p() on #if macro. It is wrong usage of builtin
function, but it is compiled on x86 without any problem, so I can't
find it before 0 day build system find it.
This commit fixes the situation by using KMALLOC_MIN_SIZE, instead of
KMALLOC_SHIFT_LOW. KMALLOC_SHIFT_LOW is parsed to ilog2() on some
architecture and this ilog2() uses __builtin_constant_p() and results in
the problem. This problem would disappear by using KMALLOC_MIN_SIZE,
since it is just constant.
Tested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'include/linux/slab.h')
| -rw-r--r-- | include/linux/slab.h | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index d015dec02bf3..5df89f777a54 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -201,17 +201,6 @@ struct kmem_cache { #ifndef KMALLOC_SHIFT_LOW #define KMALLOC_SHIFT_LOW 5 #endif - -/* - * This restriction comes from byte sized index implementation. - * Page size is normally 2^12 bytes and, in this case, if we want to use - * byte sized index which can represent 2^8 entries, the size of the object - * should be equal or greater to 2^12 / 2^8 = 2^4 = 16. - * If minimum size of kmalloc is less than 16, we use it as minimum object - * size and give up to use byte sized index. - */ -#define SLAB_OBJ_MIN_SIZE (KMALLOC_SHIFT_LOW < 4 ? \ - (1 << KMALLOC_SHIFT_LOW) : 16) #endif #ifdef CONFIG_SLUB @@ -253,6 +242,17 @@ struct kmem_cache { #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW) #endif +/* + * This restriction comes from byte sized index implementation. + * Page size is normally 2^12 bytes and, in this case, if we want to use + * byte sized index which can represent 2^8 entries, the size of the object + * should be equal or greater to 2^12 / 2^8 = 2^4 = 16. + * If minimum size of kmalloc is less than 16, we use it as minimum object + * size and give up to use byte sized index. + */ +#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \ + (KMALLOC_MIN_SIZE) : 16) + #ifndef CONFIG_SLOB extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; #ifdef CONFIG_ZONE_DMA |