slab: introduce helper functions to get/set free object

In the following patches, to get/set free objects from the freelist
is changed so that simple casting doesn't work for it. Therefore,
introduce helper functions.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 13 insertions, 7 deletions

diff --git a/mm/slab.c b/mm/slab.c
index f81176dd0a90..878354b26b72 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2548,9 +2548,15 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep,
         return freelist;
 }
 
-static inline unsigned int *slab_freelist(struct page *page)
+static inline unsigned int get_free_obj(struct page *page, unsigned int idx)
 {
-        return (unsigned int *)(page->freelist);
+        return ((unsigned int *)page->freelist)[idx];
+}
+
+static inline void set_free_obj(struct page *page,
+                                        unsigned int idx, unsigned int val)
+{
+        ((unsigned int *)(page->freelist))[idx] = val;
 }
 
 static void cache_init_objs(struct kmem_cache *cachep,
@@ -2595,7 +2601,7 @@ static void cache_init_objs(struct kmem_cache *cachep,
                 if (cachep->ctor)
                         cachep->ctor(objp);
 #endif
-                slab_freelist(page)[i] = i;
+                set_free_obj(page, i, i);
         }
 }
 
@@ -2614,7 +2620,7 @@ static void *slab_get_obj(struct kmem_cache *cachep, struct page *page,
 {
         void *objp;
 
-        objp = index_to_obj(cachep, page, slab_freelist(page)[page->active]);
+        objp = index_to_obj(cachep, page, get_free_obj(page, page->active));
         page->active++;
 #if DEBUG
         WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
@@ -2635,7 +2641,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
 
         /* Verify double free bug */
         for (i = page->active; i < cachep->num; i++) {
-                if (slab_freelist(page)[i] == objnr) {
+                if (get_free_obj(page, i) == objnr) {
                         printk(KERN_ERR "slab: double free detected in cache "
                                         "'%s', objp %p\n", cachep->name, objp);
                         BUG();
@@ -2643,7 +2649,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
         }
 #endif
         page->active--;
-        slab_freelist(page)[page->active] = objnr;
+        set_free_obj(page, page->active, objnr);
 }
 
 /*
@@ -4216,7 +4222,7 @@ static void handle_slab(unsigned long *n, struct kmem_cache *c,
 
                 for (j = page->active; j < c->num; j++) {
                         /* Skip freed item */
-                        if (slab_freelist(page)[j] == i) {
+                        if (get_free_obj(page, j) == i) {
                                 active = false;
                                 break;
                         }