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authorChristoph Lameter <clameter@sgi.com>2007-07-17 04:03:22 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:01 -0700
commit6cb8f91320d3e720351c21741da795fed580b21b (patch)
treec9f73c8b82cd0f6c534939b8b9f36e8615b0ab2d /include/linux/slab.h
parentef2ad80c7d255ed0449eda947c2d700635b7e0f5 (diff)
Slab allocators: consistent ZERO_SIZE_PTR support and NULL result semantics
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>
Diffstat (limited to 'include/linux/slab.h')
-rw-r--r--include/linux/slab.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 27402fea9b7..0289ec89300 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -31,6 +31,19 @@
#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
*/
void __init kmem_cache_init(void);