Merge branch 'core/debugobjects' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core/debugobjects' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  debugobjects: delay free of internal objects
  debugobjects: replace static objects when slab cache becomes available
  debug_objects: add boot-parameter toggle to turn object debugging off again

1 files changed, 112 insertions, 15 deletions

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 5d99be1fd988..2755a3bd16a1 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -30,7 +30,7 @@ struct debug_bucket {
 
 static struct debug_bucket      obj_hash[ODEBUG_HASH_SIZE];
 
-static struct debug_obj         obj_static_pool[ODEBUG_POOL_SIZE];
+static struct debug_obj         obj_static_pool[ODEBUG_POOL_SIZE] __initdata;
 
 static DEFINE_SPINLOCK(pool_lock);
 
@@ -50,12 +50,23 @@ static int			debug_objects_enabled __read_mostly
 
 static struct debug_obj_descr   *descr_test  __read_mostly;
 
+static void free_obj_work(struct work_struct *work);
+static DECLARE_WORK(debug_obj_work, free_obj_work);
+
 static int __init enable_object_debug(char *str)
 {
         debug_objects_enabled = 1;
         return 0;
 }
+
+static int __init disable_object_debug(char *str)
+{
+        debug_objects_enabled = 0;
+        return 0;
+}
+
 early_param("debug_objects", enable_object_debug);
+early_param("no_debug_objects", disable_object_debug);
 
 static const char *obj_states[ODEBUG_STATE_MAX] = {
         [ODEBUG_STATE_NONE]             = "none",
@@ -146,25 +157,51 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr)
 }
 
 /*
- * Put the object back into the pool or give it back to kmem_cache:
+ * workqueue function to free objects.
  */
-static void free_object(struct debug_obj *obj)
+static void free_obj_work(struct work_struct *work)
 {
-        unsigned long idx = (unsigned long)(obj - obj_static_pool);
+        struct debug_obj *obj;
         unsigned long flags;
 
-        if (obj_pool_free < ODEBUG_POOL_SIZE || idx < ODEBUG_POOL_SIZE) {
-                spin_lock_irqsave(&pool_lock, flags);
-                hlist_add_head(&obj->node, &obj_pool);
-                obj_pool_free++;
-                obj_pool_used--;
-                spin_unlock_irqrestore(&pool_lock, flags);
-        } else {
-                spin_lock_irqsave(&pool_lock, flags);
-                obj_pool_used--;
+        spin_lock_irqsave(&pool_lock, flags);
+        while (obj_pool_free > ODEBUG_POOL_SIZE) {
+                obj = hlist_entry(obj_pool.first, typeof(*obj), node);
+                hlist_del(&obj->node);
+                obj_pool_free--;
+                /*
+                 * We release pool_lock across kmem_cache_free() to
+                 * avoid contention on pool_lock.
+                 */
                 spin_unlock_irqrestore(&pool_lock, flags);
                 kmem_cache_free(obj_cache, obj);
+                spin_lock_irqsave(&pool_lock, flags);
         }
+        spin_unlock_irqrestore(&pool_lock, flags);
+}
+
+/*
+ * Put the object back into the pool and schedule work to free objects
+ * if necessary.
+ */
+static void free_object(struct debug_obj *obj)
+{
+        unsigned long flags;
+        int sched = 0;
+
+        spin_lock_irqsave(&pool_lock, flags);
+        /*
+         * schedule work when the pool is filled and the cache is
+         * initialized:
+         */
+        if (obj_pool_free > ODEBUG_POOL_SIZE && obj_cache)
+                sched = !work_pending(&debug_obj_work);
+        hlist_add_head(&obj->node, &obj_pool);
+        obj_pool_free++;
+        obj_pool_used--;
+        spin_unlock_irqrestore(&pool_lock, flags);
+        if (sched)
+                schedule_work(&debug_obj_work);
 }
 
 /*
@@ -876,6 +913,63 @@ void __init debug_objects_early_init(void)
 }
 
 /*
+ * Convert the statically allocated objects to dynamic ones:
+ */
+static int debug_objects_replace_static_objects(void)
+{
+        struct debug_bucket *db = obj_hash;
+        struct hlist_node *node, *tmp;
+        struct debug_obj *obj, *new;
+        HLIST_HEAD(objects);
+        int i, cnt = 0;
+
+        for (i = 0; i < ODEBUG_POOL_SIZE; i++) {
+                obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
+                if (!obj)
+                        goto free;
+                hlist_add_head(&obj->node, &objects);
+        }
+
+        /*
+         * When debug_objects_mem_init() is called we know that only
+         * one CPU is up, so disabling interrupts is enough
+         * protection. This avoids the lockdep hell of lock ordering.
+         */
+        local_irq_disable();
+
+        /* Remove the statically allocated objects from the pool */
+        hlist_for_each_entry_safe(obj, node, tmp, &obj_pool, node)
+                hlist_del(&obj->node);
+        /* Move the allocated objects to the pool */
+        hlist_move_list(&objects, &obj_pool);
+
+        /* Replace the active object references */
+        for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
+                hlist_move_list(&db->list, &objects);
+
+                hlist_for_each_entry(obj, node, &objects, node) {
+                        new = hlist_entry(obj_pool.first, typeof(*obj), node);
+                        hlist_del(&new->node);
+                        /* copy object data */
+                        *new = *obj;
+                        hlist_add_head(&new->node, &db->list);
+                        cnt++;
+                }
+        }
+
+        printk(KERN_DEBUG "ODEBUG: %d of %d active objects replaced\n", cnt,
+               obj_pool_used);
+        local_irq_enable();
+        return 0;
+free:
+        hlist_for_each_entry_safe(obj, node, tmp, &objects, node) {
+                hlist_del(&obj->node);
+                kmem_cache_free(obj_cache, obj);
+        }
+        return -ENOMEM;
+}
+
+/*
  * Called after the kmem_caches are functional to setup a dedicated
  * cache pool, which has the SLAB_DEBUG_OBJECTS flag set. This flag
  * prevents that the debug code is called on kmem_cache_free() for the
@@ -890,8 +984,11 @@ void __init debug_objects_mem_init(void)
                                       sizeof (struct debug_obj), 0,
                                       SLAB_DEBUG_OBJECTS, NULL);
 
-        if (!obj_cache)
+        if (!obj_cache || debug_objects_replace_static_objects()) {
                 debug_objects_enabled = 0;
-        else
+                if (obj_cache)
+                        kmem_cache_destroy(obj_cache);
+                printk(KERN_WARNING "ODEBUG: out of memory.\n");
+        } else
                 debug_objects_selftest();
 }