staging: zsmalloc: zsmalloc: use unsigned long instead of void *

We should use unsigned long as handle instead of void * to avoid any
confusion. Without this, users may just treat zs_malloc return value as
a pointer and try to deference it.

This patch passed compile test(zram, zcache and ramster) and zram is
tested on qemu.

changelog
  * from v2
	- remove hval pointed out by Nitin
	- based on next-20120607
  * from v1
	- change zcache's zv_create return value
	- baesd on next-20120604

Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 17 insertions, 19 deletions

diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
index 449673773286..8e830eeca729 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/drivers/staging/zsmalloc/zsmalloc-main.c
@@ -247,13 +247,11 @@ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
 }
 
 /* Decode <page, obj_idx> pair from the given object handle */
-static void obj_handle_to_location(void *handle, struct page **page,
+static void obj_handle_to_location(unsigned long handle, struct page **page,
 				unsigned long *obj_idx)
 {
-	unsigned long hval = (unsigned long)handle;
-
-	*page = pfn_to_page(hval >> OBJ_INDEX_BITS);
-	*obj_idx = hval & OBJ_INDEX_MASK;
+	*page = pfn_to_page(handle >> OBJ_INDEX_BITS);
+	*obj_idx = handle & OBJ_INDEX_MASK;
 }
 
 static unsigned long obj_idx_to_offset(struct page *page,
@@ -568,12 +566,12 @@ EXPORT_SYMBOL_GPL(zs_destroy_pool);
  * @size: size of block to allocate
  *
  * On success, handle to the allocated object is returned,
- * otherwise NULL.
+ * otherwise 0.
  * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
  */
-void *zs_malloc(struct zs_pool *pool, size_t size)
+unsigned long zs_malloc(struct zs_pool *pool, size_t size)
 {
-	void *obj;
+	unsigned long obj;
 	struct link_free *link;
 	int class_idx;
 	struct size_class *class;
@@ -582,7 +580,7 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
 	unsigned long m_objidx, m_offset;
 
 	if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
-		return NULL;
+		return 0;
 
 	class_idx = get_size_class_index(size);
 	class = &pool->size_class[class_idx];
@@ -595,14 +593,14 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
 		spin_unlock(&class->lock);
 		first_page = alloc_zspage(class, pool->flags);
 		if (unlikely(!first_page))
-			return NULL;
+			return 0;
 
 		set_zspage_mapping(first_page, class->index, ZS_EMPTY);
 		spin_lock(&class->lock);
 		class->pages_allocated += class->pages_per_zspage;
 	}
 
-	obj = first_page->freelist;
+	obj = (unsigned long)first_page->freelist;
 	obj_handle_to_location(obj, &m_page, &m_objidx);
 	m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
 
@@ -621,7 +619,7 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
 }
 EXPORT_SYMBOL_GPL(zs_malloc);
 
-void zs_free(struct zs_pool *pool, void *obj)
+void zs_free(struct zs_pool *pool, unsigned long obj)
 {
 	struct link_free *link;
 	struct page *first_page, *f_page;
@@ -648,7 +646,7 @@ void zs_free(struct zs_pool *pool, void *obj)
 							+ f_offset);
 	link->next = first_page->freelist;
 	kunmap_atomic(link);
-	first_page->freelist = obj;
+	first_page->freelist = (void *)obj;
 
 	first_page->inuse--;
 	fullness = fix_fullness_group(pool, first_page);
@@ -672,7 +670,7 @@ EXPORT_SYMBOL_GPL(zs_free);
  * this function. When done with the object, it must be unmapped using
  * zs_unmap_object
 */
-void *zs_map_object(struct zs_pool *pool, void *handle)
+void *zs_map_object(struct zs_pool *pool, unsigned long handle)
 {
 	struct page *page;
 	unsigned long obj_idx, off;
@@ -712,7 +710,7 @@ void *zs_map_object(struct zs_pool *pool, void *handle)
 }
 EXPORT_SYMBOL_GPL(zs_map_object);
 
-void zs_unmap_object(struct zs_pool *pool, void *handle)
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 {
 	struct page *page;
 	unsigned long obj_idx, off;
diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/drivers/staging/zsmalloc/zsmalloc.h
index 949384ee7491..485cbb1a5ac8 100644
--- a/drivers/staging/zsmalloc/zsmalloc.h
+++ b/drivers/staging/zsmalloc/zsmalloc.h
@@ -20,11 +20,11 @@ struct zs_pool;
 struct zs_pool *zs_create_pool(const char *name, gfp_t flags);
 void zs_destroy_pool(struct zs_pool *pool);
 
-void *zs_malloc(struct zs_pool *pool, size_t size);
-void zs_free(struct zs_pool *pool, void *obj);
+unsigned long zs_malloc(struct zs_pool *pool, size_t size);
+void zs_free(struct zs_pool *pool, unsigned long obj);
 
-void *zs_map_object(struct zs_pool *pool, void *handle);
-void zs_unmap_object(struct zs_pool *pool, void *handle);
+void *zs_map_object(struct zs_pool *pool, unsigned long handle);
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
 
 u64 zs_get_total_size_bytes(struct zs_pool *pool);