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SLUB: Simplify debug code
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Consolidate functionality into the #ifdef section.

Extract tracing into one subroutine.

Move object debug processing into the #ifdef section so that the
code in __slab_alloc and __slab_free becomes minimal.

Reduce number of functions we need to provide stubs for in the !SLUB_DEBUG case.

Signed-off-by: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Christoph Lameter authored and Linus Torvalds committed May 17, 2007
1 parent a35afb8 commit 3ec0974
Showing 1 changed file with 57 additions and 55 deletions.
112 changes: 57 additions & 55 deletions mm/slub.c
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Original file line number Diff line number Diff line change
Expand Up @@ -742,6 +742,22 @@ static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
return search == NULL;
}

static void trace(struct kmem_cache *s, struct page *page, void *object, int alloc)
{
if (s->flags & SLAB_TRACE) {
printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
s->name,
alloc ? "alloc" : "free",
object, page->inuse,
page->freelist);

if (!alloc)
print_section("Object", (void *)object, s->objsize);

dump_stack();
}
}

/*
* Tracking of fully allocated slabs for debugging purposes.
*/
Expand All @@ -766,8 +782,18 @@ static void remove_full(struct kmem_cache *s, struct page *page)
spin_unlock(&n->list_lock);
}

static int alloc_object_checks(struct kmem_cache *s, struct page *page,
void *object)
static void setup_object_debug(struct kmem_cache *s, struct page *page,
void *object)
{
if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
return;

init_object(s, object, 0);
init_tracking(s, object);
}

static int alloc_debug_processing(struct kmem_cache *s, struct page *page,
void *object, void *addr)
{
if (!check_slab(s, page))
goto bad;
Expand All @@ -782,13 +808,16 @@ static int alloc_object_checks(struct kmem_cache *s, struct page *page,
goto bad;
}

if (!object)
return 1;

if (!check_object(s, page, object, 0))
if (object && !check_object(s, page, object, 0))
goto bad;

/* Success perform special debug activities for allocs */
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_ALLOC, addr);
trace(s, page, object, 1);
init_object(s, object, 1);
return 1;

bad:
if (PageSlab(page)) {
/*
Expand All @@ -806,8 +835,8 @@ static int alloc_object_checks(struct kmem_cache *s, struct page *page,
return 0;
}

static int free_object_checks(struct kmem_cache *s, struct page *page,
void *object)
static int free_debug_processing(struct kmem_cache *s, struct page *page,
void *object, void *addr)
{
if (!check_slab(s, page))
goto fail;
Expand Down Expand Up @@ -841,29 +870,22 @@ static int free_object_checks(struct kmem_cache *s, struct page *page,
"to slab %s", object, page->slab->name);
goto fail;
}

/* Special debug activities for freeing objects */
if (!SlabFrozen(page) && !page->freelist)
remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
init_object(s, object, 0);
return 1;

fail:
printk(KERN_ERR "@@@ SLUB: %s slab 0x%p object at 0x%p not freed.\n",
s->name, page, object);
return 0;
}

static void trace(struct kmem_cache *s, struct page *page, void *object, int alloc)
{
if (s->flags & SLAB_TRACE) {
printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
s->name,
alloc ? "alloc" : "free",
object, page->inuse,
page->freelist);

if (!alloc)
print_section("Object", (void *)object, s->objsize);

dump_stack();
}
}

static int __init setup_slub_debug(char *str)
{
if (!str || *str != '=')
Expand Down Expand Up @@ -932,26 +954,20 @@ static void kmem_cache_open_debug_check(struct kmem_cache *s)
s->flags |= slub_debug;
}
#else
static inline void setup_object_debug(struct kmem_cache *s,
struct page *page, void *object) {}

static inline int alloc_object_checks(struct kmem_cache *s,
struct page *page, void *object) { return 0; }
static inline int alloc_debug_processing(struct kmem_cache *s,
struct page *page, void *object, void *addr) { return 0; }

static inline int free_object_checks(struct kmem_cache *s,
struct page *page, void *object) { return 0; }
static inline int free_debug_processing(struct kmem_cache *s,
struct page *page, void *object, void *addr) { return 0; }

static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
static inline void remove_full(struct kmem_cache *s, struct page *page) {}
static inline void trace(struct kmem_cache *s, struct page *page,
void *object, int alloc) {}
static inline void init_object(struct kmem_cache *s,
void *object, int active) {}
static inline void init_tracking(struct kmem_cache *s, void *object) {}
static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
void *object, int active) { return 1; }
static inline void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, void *addr) {}
static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
static inline void kmem_cache_open_debug_check(struct kmem_cache *s) {}
#define slub_debug 0
#endif
Expand Down Expand Up @@ -988,11 +1004,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
static void setup_object(struct kmem_cache *s, struct page *page,
void *object)
{
if (SlabDebug(page)) {
init_object(s, object, 0);
init_tracking(s, object);
}

setup_object_debug(s, page, object);
if (unlikely(s->ctor))
s->ctor(object, s, 0);
}
Expand Down Expand Up @@ -1449,12 +1461,8 @@ static void *__slab_alloc(struct kmem_cache *s,
return NULL;
debug:
object = page->freelist;
if (!alloc_object_checks(s, page, object))
if (!alloc_debug_processing(s, page, object, addr))
goto another_slab;
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_ALLOC, addr);
trace(s, page, object, 1);
init_object(s, object, 1);

page->inuse++;
page->freelist = object[page->offset];
Expand Down Expand Up @@ -1561,14 +1569,8 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
return;

debug:
if (!free_object_checks(s, page, x))
if (!free_debug_processing(s, page, x, addr))
goto out_unlock;
if (!SlabFrozen(page) && !page->freelist)
remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, x, TRACK_FREE, addr);
trace(s, page, object, 0);
init_object(s, object, 0);
goto checks_ok;
}

Expand Down Expand Up @@ -1805,7 +1807,7 @@ static struct kmem_cache_node * __init early_kmem_cache_node_alloc(gfp_t gfpflag
page->freelist = get_freepointer(kmalloc_caches, n);
page->inuse++;
kmalloc_caches->node[node] = n;
init_object(kmalloc_caches, n, 1);
setup_object_debug(kmalloc_caches, page, n);
init_kmem_cache_node(n);
atomic_long_inc(&n->nr_slabs);
add_partial(n, page);
Expand Down

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