[PATCH] mempool: add kmalloc allocator

Add another allocator to the common mempool code: a kmalloc/kfree allocator

This will be used by the next patch in the series to replace duplicate
mempool-backed kmalloc allocators in several places in the kernel.  It is also
very likely that there will be more users in the future.
Signed-off-by: Matthew Dobson <colpatch@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/mempool.h

@@ -38,6 +38,18 @@ extern void mempool_free(void *element, mempool_t *pool);
 void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data);
 void mempool_free_slab(void *element, void *pool_data);
 
+/*
+ * A mempool_alloc_t and mempool_free_t to kmalloc the amount of memory
+ * specified by pool_data
+ */
+void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data);
+void mempool_kfree(void *element, void *pool_data);
+static inline mempool_t *mempool_create_kmalloc_pool(int min_nr, size_t size)
+{
+	return mempool_create(min_nr, mempool_kmalloc, mempool_kfree,
+			      (void *) size);
+}
+
 /*
  * A mempool_alloc_t and mempool_free_t for a simple page allocator that
  * allocates pages of the order specified by pool_data

mm/mempool.c

@@ -290,6 +290,23 @@ void mempool_free_slab(void *element, void *pool_data)
 }
 EXPORT_SYMBOL(mempool_free_slab);
 
+/*
+ * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
+ * specfied by pool_data
+ */
+void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
+{
+	size_t size = (size_t) pool_data;
+	return kmalloc(size, gfp_mask);
+}
+EXPORT_SYMBOL(mempool_kmalloc);
+
+void mempool_kfree(void *element, void *pool_data)
+{
+	kfree(element);
+}
+EXPORT_SYMBOL(mempool_kfree);
+
 /*
  * A simple mempool-backed page allocator that allocates pages
  * of the order specified by pool_data.