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Subject[PATCH v2 10/15] slab: remove kmem_bufctl_t
Date
Now, we changed the management method of free objects of the slab and
there is no need to use special value, BUFCTL_END, BUFCTL_FREE and
BUFCTL_ACTIVE. So remove them.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/mm/slab.c b/mm/slab.c
index 05fe37e..6ced1cc 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -163,27 +163,7 @@
*/
static bool pfmemalloc_active __read_mostly;

-/*
- * kmem_bufctl_t:
- *
- * Bufctl's are used for linking objs within a slab
- * linked offsets.
- *
- * This implementation relies on "struct page" for locating the cache &
- * slab an object belongs to.
- * This allows the bufctl structure to be small (one int), but limits
- * the number of objects a slab (not a cache) can contain when off-slab
- * bufctls are used. The limit is the size of the largest general cache
- * that does not use off-slab slabs.
- * For 32bit archs with 4 kB pages, is this 56.
- * This is not serious, as it is only for large objects, when it is unwise
- * to have too many per slab.
- * Note: This limit can be raised by introducing a general cache whose size
- * is less than 512 (PAGE_SIZE<<3), but greater than 256.
- */
-
-typedef unsigned int kmem_bufctl_t;
-#define SLAB_LIMIT (((kmem_bufctl_t)(~0U))-3)
+#define SLAB_LIMIT (((unsigned int)(~0U))-1)

/*
* struct slab
@@ -197,7 +177,7 @@ struct slab {
struct list_head list;
void *s_mem; /* including colour offset */
unsigned int inuse; /* num of objs active in slab */
- kmem_bufctl_t free;
+ unsigned int free;
};
};

@@ -613,7 +593,7 @@ static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)

static size_t slab_mgmt_size(size_t nr_objs, size_t align)
{
- return ALIGN(sizeof(struct slab)+nr_objs*sizeof(kmem_bufctl_t), align);
+ return ALIGN(sizeof(struct slab)+nr_objs*sizeof(unsigned int), align);
}

/*
@@ -633,7 +613,7 @@ static void cache_estimate(unsigned long gfporder, size_t buffer_size,
* slab is used for:
*
* - The struct slab
- * - One kmem_bufctl_t for each object
+ * - One unsigned int for each object
* - Padding to respect alignment of @align
* - @buffer_size bytes for each object
*
@@ -658,7 +638,7 @@ static void cache_estimate(unsigned long gfporder, size_t buffer_size,
* into account.
*/
nr_objs = (slab_size - sizeof(struct slab)) /
- (buffer_size + sizeof(kmem_bufctl_t));
+ (buffer_size + sizeof(unsigned int));

/*
* This calculated number will be either the right
@@ -2068,7 +2048,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
* looping condition in cache_grow().
*/
offslab_limit = size - sizeof(struct slab);
- offslab_limit /= sizeof(kmem_bufctl_t);
+ offslab_limit /= sizeof(unsigned int);

if (num > offslab_limit)
break;
@@ -2309,7 +2289,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (!cachep->num)
return -E2BIG;

- slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
+ slab_size = ALIGN(cachep->num * sizeof(unsigned int)
+ sizeof(struct slab), cachep->align);

/*
@@ -2324,7 +2304,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (flags & CFLGS_OFF_SLAB) {
/* really off slab. No need for manual alignment */
slab_size =
- cachep->num * sizeof(kmem_bufctl_t) + sizeof(struct slab);
+ cachep->num * sizeof(unsigned int) + sizeof(struct slab);

#ifdef CONFIG_PAGE_POISONING
/* If we're going to use the generic kernel_map_pages()
@@ -2603,9 +2583,9 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep,
return slabp;
}

-static inline kmem_bufctl_t *slab_bufctl(struct slab *slabp)
+static inline unsigned int *slab_bufctl(struct slab *slabp)
{
- return (kmem_bufctl_t *) (slabp + 1);
+ return (unsigned int *) (slabp + 1);
}

static void cache_init_objs(struct kmem_cache *cachep,
@@ -2684,7 +2664,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
{
unsigned int objnr = obj_to_index(cachep, slabp, objp);
#if DEBUG
- kmem_bufctl_t i;
+ unsigned int i;

/* Verify that the slab belongs to the intended node */
WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
--
1.7.9.5


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