slab: Common Kmalloc cache determination

Extract the optimized lookup functions from slub and put them into
slab_common.c. Then make slab use these functions as well.

Joonsoo notes that this fixes some issues with constant folding which
also reduces the code size for slub.

https://lkml.org/lkml/2012/10/20/82

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 10 insertions, 31 deletions

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 3701896..16341e5 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -115,29 +115,6 @@ struct kmem_cache {
 	struct kmem_cache_node *node[MAX_NUMNODES];
 };
 
-#ifdef CONFIG_ZONE_DMA
-#define SLUB_DMA __GFP_DMA
-#else
-/* Disable DMA functionality */
-#define SLUB_DMA (__force gfp_t)0
-#endif
-
-/*
- * Find the slab cache for a given combination of allocation flags and size.
- *
- * This ought to end up with a global pointer to the right cache
- * in kmalloc_caches.
- */
-static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
-{
-	int index = kmalloc_index(size);
-
-	if (index == 0)
-		return NULL;
-
-	return kmalloc_caches[index];
-}
-
 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 void *__kmalloc(size_t size, gfp_t flags);
 
@@ -195,13 +172,14 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
 		if (size > KMALLOC_MAX_CACHE_SIZE)
 			return kmalloc_large(size, flags);
 
-		if (!(flags & SLUB_DMA)) {
-			struct kmem_cache *s = kmalloc_slab(size);
+		if (!(flags & GFP_DMA)) {
+			int index = kmalloc_index(size);
 
-			if (!s)
+			if (!index)
 				return ZERO_SIZE_PTR;
 
-			return kmem_cache_alloc_trace(s, flags, size);
+			return kmem_cache_alloc_trace(kmalloc_caches[index],
+					flags, size);
 		}
 	}
 	return __kmalloc(size, flags);
@@ -228,13 +206,14 @@ kmem_cache_alloc_node_trace(struct kmem_cache *s,
 static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	if (__builtin_constant_p(size) &&
-		size <= KMALLOC_MAX_CACHE_SIZE && !(flags & SLUB_DMA)) {
-			struct kmem_cache *s = kmalloc_slab(size);
+		size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
+		int index = kmalloc_index(size);
 
-		if (!s)
+		if (!index)
 			return ZERO_SIZE_PTR;
 
-		return kmem_cache_alloc_node_trace(s, flags, node, size);
+		return kmem_cache_alloc_node_trace(kmalloc_caches[index],
+			       flags, node, size);
 	}
 	return __kmalloc_node(size, flags, node);
 }