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Subject[slubllv3 02/21] slub: get_map() function to establish map of free objects in a slab
The bit map of free objects in a slab page is determined in various functions
if debugging is enabled.

Provide a common function for that purpose.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
mm/slub.c | 34 ++++++++++++++++++++++------------
1 file changed, 22 insertions(+), 12 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2011-03-30 14:09:27.000000000 -0500
+++ linux-2.6/mm/slub.c 2011-03-30 14:30:24.000000000 -0500
@@ -271,10 +271,6 @@ static inline void set_freepointer(struc
for (__p = (__addr); __p < (__addr) + (__objects) * (__s)->size;\
__p += (__s)->size)

-/* Scan freelist */
-#define for_each_free_object(__p, __s, __free) \
- for (__p = (__free); __p; __p = get_freepointer((__s), __p))
-
/* Determine object index from a given position */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
{
@@ -330,6 +326,21 @@ static inline int oo_objects(struct kmem
return x.x & OO_MASK;
}

+/*
+ * Determine a map of object in use on a page.
+ *
+ * Slab lock or node listlock must be held to guarantee that the page does
+ * not vanish from under us.
+ */
+static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
+{
+ void *p;
+ void *addr = page_address(page);
+
+ for (p = page->freelist; p; p = get_freepointer(s, p))
+ set_bit(slab_index(p, s, addr), map);
+}
+
#ifdef CONFIG_SLUB_DEBUG
/*
* Debug settings:
@@ -2673,9 +2684,8 @@ static void list_slab_objects(struct kme
return;
slab_err(s, page, "%s", text);
slab_lock(page);
- for_each_free_object(p, s, page->freelist)
- set_bit(slab_index(p, s, addr), map);

+ get_map(s, page, map);
for_each_object(p, s, addr, page->objects) {

if (!test_bit(slab_index(p, s, addr), map)) {
@@ -3610,10 +3620,11 @@ static int validate_slab(struct kmem_cac
/* Now we know that a valid freelist exists */
bitmap_zero(map, page->objects);

- for_each_free_object(p, s, page->freelist) {
- set_bit(slab_index(p, s, addr), map);
- if (!check_object(s, page, p, SLUB_RED_INACTIVE))
- return 0;
+ get_map(s, page, map);
+ for_each_object(p, s, addr, page->objects) {
+ if (test_bit(slab_index(p, s, addr), map))
+ if (!check_object(s, page, p, SLUB_RED_INACTIVE))
+ return 0;
}

for_each_object(p, s, addr, page->objects)
@@ -3821,8 +3832,7 @@ static void process_slab(struct loc_trac
void *p;

bitmap_zero(map, page->objects);
- for_each_free_object(p, s, page->freelist)
- set_bit(slab_index(p, s, addr), map);
+ get_map(s, page, map);

for_each_object(p, s, addr, page->objects)
if (!test_bit(slab_index(p, s, addr), map))


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