On Fri, 15 Apr 2011, Christoph Lameter wrote:
> 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.
>
Although it makes writing to /sys/kernel/slab/cache/validate slower
because of the double iteration in validate_slab().
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
>
> ---
> 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:
This generates a warning without CONFIG_SLUB_DEBUG:
mm/slub.c:335: warning: âget_mapâ defined but not used