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Slab allocators: consistent ZERO_SIZE_PTR support and NULL result semantics

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Define ZERO_OR_NULL_PTR macro to be able to remove the checks from the
allocators.  Move ZERO_SIZE_PTR related stuff into slab.h.

Make ZERO_SIZE_PTR work for all slab allocators and get rid of the
WARN_ON_ONCE(size == 0) that is still remaining in SLAB.

Make slub return NULL like the other allocators if a too large memory segment
is requested via __kmalloc.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Lameter
2007-07-17 04:03:22 -07:00
committed by Linus Torvalds
parent ef2ad80c7d
commit 6cb8f91320
7 changed files with 57 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/slab.h
View File

@@ -30,6 +30,19 @@
#define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */
#define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */
/*
* ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
*
* Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
*
* ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
* Both make kfree a no-op.
*/
#define ZERO_SIZE_PTR ((void *)16)
#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) < \
(unsigned long)ZERO_SIZE_PTR)
/*
* struct kmem_cache related prototypes
*/

12
include/linux/slab_def.h
View File

@@ -32,6 +32,10 @@ static inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
int i = 0;
if (!size)
return ZERO_SIZE_PTR;
#define CACHE(x) \
if (size <= x) \
goto found; \
@@ -58,6 +62,10 @@ static inline void *kzalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
int i = 0;
if (!size)
return ZERO_SIZE_PTR;
#define CACHE(x) \
if (size <= x) \
goto found; \
@@ -88,6 +96,10 @@ static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size)) {
int i = 0;
if (!size)
return ZERO_SIZE_PTR;
#define CACHE(x) \
if (size <= x) \
goto found; \

12
include/linux/slub_def.h
View File

@@ -159,18 +159,6 @@ static inline struct kmem_cache *kmalloc_slab(size_t size)
#define SLUB_DMA 0
#endif
/*
* ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
*
* Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
*
* ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
* Both make kfree a no-op.
*/
#define ZERO_SIZE_PTR ((void *)16)
void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
void *__kmalloc(size_t size, gfp_t flags);