Merge tag 'core-debugobjects-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull debugobjects updates from Thomas Gleixner:

 - Use the threshold to check for the pool refill condition and not the
   run time recorded all time low fill value, which is lower than the
   threshold and therefore causes refills to be delayed.

 - KCSAN annotation updates and simplification of the fill_pool() code.

* tag 'core-debugobjects-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobjects: Remove redundant checks in fill_pool()
  debugobjects: Fix conditions in fill_pool()
  debugobjects: Fix the compilation attributes of some global variables

Author: torvalds

lib/debugobjects.c

@@ -70,10 +70,10 @@ static HLIST_HEAD(obj_to_free);
  * made at debug_stats_show(). Both obj_pool_min_free and obj_pool_max_used
  * can be off.
  */
-static int			obj_pool_min_free = ODEBUG_POOL_SIZE;
-static int			obj_pool_free = ODEBUG_POOL_SIZE;
+static int __data_racy		obj_pool_min_free = ODEBUG_POOL_SIZE;
+static int __data_racy		obj_pool_free = ODEBUG_POOL_SIZE;
 static int			obj_pool_used;
-static int			obj_pool_max_used;
+static int __data_racy		obj_pool_max_used;
 static bool			obj_freeing;
 /* The number of objs on the global free list */
 static int			obj_nr_tofree;
@@ -84,9 +84,9 @@ static int __data_racy			debug_objects_fixups __read_mostly;
 static int __data_racy			debug_objects_warnings __read_mostly;
 static int __data_racy			debug_objects_enabled __read_mostly
 					= CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;
-static int __data_racy			debug_objects_pool_size __read_mostly
+static int				debug_objects_pool_size __ro_after_init
 					= ODEBUG_POOL_SIZE;
-static int __data_racy			debug_objects_pool_min_level __read_mostly
+static int				debug_objects_pool_min_level __ro_after_init
 					= ODEBUG_POOL_MIN_LEVEL;
 
 static const struct debug_obj_descr *descr_test  __read_mostly;
@@ -95,8 +95,8 @@ static struct kmem_cache	*obj_cache __ro_after_init;
 /*
  * Track numbers of kmem_cache_alloc()/free() calls done.
  */
-static int			debug_objects_allocated;
-static int			debug_objects_freed;
+static int __data_racy		debug_objects_allocated;
+static int __data_racy		debug_objects_freed;
 
 static void free_obj_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(debug_obj_work, free_obj_work);
@@ -135,20 +135,19 @@ static void fill_pool(void)
 		return;
 
 	/*
-	 * Reuse objs from the global free list; they will be reinitialized
-	 * when allocating.
+	 * Reuse objs from the global obj_to_free list; they will be
+	 * reinitialized when allocating.
 	 *
-	 * Both obj_nr_tofree and obj_pool_free are checked locklessly; the
-	 * READ_ONCE()s pair with the WRITE_ONCE()s in pool_lock critical
-	 * sections.
+	 * obj_nr_tofree is checked locklessly; the READ_ONCE() pairs with
+	 * the WRITE_ONCE() in pool_lock critical sections.
 	 */
-	while (READ_ONCE(obj_nr_tofree) && (READ_ONCE(obj_pool_free) < obj_pool_min_free)) {
+	if (READ_ONCE(obj_nr_tofree)) {
 		raw_spin_lock_irqsave(&pool_lock, flags);
 		/*
 		 * Recheck with the lock held as the worker thread might have
 		 * won the race and freed the global free list already.
 		 */
-		while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {
+		while (obj_nr_tofree && (obj_pool_free < debug_objects_pool_min_level)) {
 			obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
 			hlist_del(&obj->node);
 			WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);