Commit 534b0a8b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'core-debugobjects-2020-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull debugobjects update from Thomas Gleixner:
 "A single commit for debug objects which fixes a pile of potential data
  races detected by KCSAN"

* tag 'core-debugobjects-2020-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobjects: Fix various data races
parents b11c89a1 35fd7a63

lib/debugobjects.c

+25 −21
Original line number Diff line number Diff line
@@ -132,14 +132,18 @@ static void fill_pool(void) 
	struct debug_obj *obj;

	unsigned long flags;



	if (likely(obj_pool_free >= debug_objects_pool_min_level))

	if (likely(READ_ONCE(obj_pool_free) >= debug_objects_pool_min_level))

		return;



	/*

	 * Reuse objs from the global 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.

	 */

	while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {

	while (READ_ONCE(obj_nr_tofree) && (READ_ONCE(obj_pool_free) < obj_pool_min_free)) {

		raw_spin_lock_irqsave(&pool_lock, flags);

		/*

		 * Recheck with the lock held as the worker thread might have
@@ -148,9 +152,9 @@ static void fill_pool(void) 
		while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {

			obj = hlist_entry(obj_to_free.first, typeof(*obj), node);

			hlist_del(&obj->node);

			obj_nr_tofree--;

			WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);

			hlist_add_head(&obj->node, &obj_pool);

			obj_pool_free++;

			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

		}

		raw_spin_unlock_irqrestore(&pool_lock, flags);

	}
@@ -158,7 +162,7 @@ static void fill_pool(void) 
	if (unlikely(!obj_cache))

		return;



	while (obj_pool_free < debug_objects_pool_min_level) {

	while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {

		struct debug_obj *new[ODEBUG_BATCH_SIZE];

		int cnt;
@@ -174,7 +178,7 @@ static void fill_pool(void) 
		while (cnt) {

			hlist_add_head(&new[--cnt]->node, &obj_pool);

			debug_objects_allocated++;

			obj_pool_free++;

			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

		}

		raw_spin_unlock_irqrestore(&pool_lock, flags);

	}
@@ -236,7 +240,7 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) 
	obj = __alloc_object(&obj_pool);

	if (obj) {

		obj_pool_used++;

		obj_pool_free--;

		WRITE_ONCE(obj_pool_free, obj_pool_free - 1);



		/*

		 * Looking ahead, allocate one batch of debug objects and
@@ -255,7 +259,7 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) 
					       &percpu_pool->free_objs);

				percpu_pool->obj_free++;

				obj_pool_used++;

				obj_pool_free--;

				WRITE_ONCE(obj_pool_free, obj_pool_free - 1);

			}

		}
@@ -309,8 +313,8 @@ static void free_obj_work(struct work_struct *work) 
		obj = hlist_entry(obj_to_free.first, typeof(*obj), node);

		hlist_del(&obj->node);

		hlist_add_head(&obj->node, &obj_pool);

		obj_pool_free++;

		obj_nr_tofree--;

		WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

		WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);

	}

	raw_spin_unlock_irqrestore(&pool_lock, flags);

	return;
@@ -324,7 +328,7 @@ free_objs: 
	if (obj_nr_tofree) {

		hlist_move_list(&obj_to_free, &tofree);

		debug_objects_freed += obj_nr_tofree;

		obj_nr_tofree = 0;

		WRITE_ONCE(obj_nr_tofree, 0);

	}

	raw_spin_unlock_irqrestore(&pool_lock, flags);
@@ -375,10 +379,10 @@ free_to_obj_pool: 
	obj_pool_used--;



	if (work) {

		obj_nr_tofree++;

		WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);

		hlist_add_head(&obj->node, &obj_to_free);

		if (lookahead_count) {

			obj_nr_tofree += lookahead_count;

			WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + lookahead_count);

			obj_pool_used -= lookahead_count;

			while (lookahead_count) {

				hlist_add_head(&objs[--lookahead_count]->node,
@@ -396,15 +400,15 @@ free_to_obj_pool: 
			for (i = 0; i < ODEBUG_BATCH_SIZE; i++) {

				obj = __alloc_object(&obj_pool);

				hlist_add_head(&obj->node, &obj_to_free);

				obj_pool_free--;

				obj_nr_tofree++;

				WRITE_ONCE(obj_pool_free, obj_pool_free - 1);

				WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);

			}

		}

	} else {

		obj_pool_free++;

		WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

		hlist_add_head(&obj->node, &obj_pool);

		if (lookahead_count) {

			obj_pool_free += lookahead_count;

			WRITE_ONCE(obj_pool_free, obj_pool_free + lookahead_count);

			obj_pool_used -= lookahead_count;

			while (lookahead_count) {

				hlist_add_head(&objs[--lookahead_count]->node,
@@ -423,7 +427,7 @@ free_to_obj_pool: 
static void free_object(struct debug_obj *obj)

{

	__free_object(obj);

	if (!obj_freeing && obj_nr_tofree) {

	if (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {

		WRITE_ONCE(obj_freeing, true);

		schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);

	}
@@ -982,7 +986,7 @@ repeat: 
		debug_objects_maxchecked = objs_checked;



	/* Schedule work to actually kmem_cache_free() objects */

	if (!obj_freeing && obj_nr_tofree) {

	if (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {

		WRITE_ONCE(obj_freeing, true);

		schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);

	}
@@ -1008,12 +1012,12 @@ static int debug_stats_show(struct seq_file *m, void *v) 
	seq_printf(m, "max_checked   :%d\n", debug_objects_maxchecked);

	seq_printf(m, "warnings      :%d\n", debug_objects_warnings);

	seq_printf(m, "fixups        :%d\n", debug_objects_fixups);

	seq_printf(m, "pool_free     :%d\n", obj_pool_free + obj_percpu_free);

	seq_printf(m, "pool_free     :%d\n", READ_ONCE(obj_pool_free) + obj_percpu_free);

	seq_printf(m, "pool_pcp_free :%d\n", obj_percpu_free);

	seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);

	seq_printf(m, "pool_used     :%d\n", obj_pool_used - obj_percpu_free);

	seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);

	seq_printf(m, "on_free_list  :%d\n", obj_nr_tofree);

	seq_printf(m, "on_free_list  :%d\n", READ_ONCE(obj_nr_tofree));

	seq_printf(m, "objs_allocated:%d\n", debug_objects_allocated);

	seq_printf(m, "objs_freed    :%d\n", debug_objects_freed);

	return 0;

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