Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1036 insertions, 0 deletions

diff --git a/lib/test_objagg.c b/lib/test_objagg.c
new file mode 100644
index 000000000..f21e3ae01
--- /dev/null
+++ b/lib/test_objagg.c
@@ -0,0 +1,1036 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/* Copyright (c) 2018 Mellanox Technologies. All rights reserved */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/objagg.h>
+
+struct tokey {
+	unsigned int id;
+};
+
+#define NUM_KEYS 32
+
+static int key_id_index(unsigned int key_id)
+{
+	if (key_id >= NUM_KEYS) {
+		WARN_ON(1);
+		return 0;
+	}
+	return key_id;
+}
+
+#define BUF_LEN 128
+
+struct world {
+	unsigned int root_count;
+	unsigned int delta_count;
+	char next_root_buf[BUF_LEN];
+	struct objagg_obj *objagg_objs[NUM_KEYS];
+	unsigned int key_refs[NUM_KEYS];
+};
+
+struct root {
+	struct tokey key;
+	char buf[BUF_LEN];
+};
+
+struct delta {
+	unsigned int key_id_diff;
+};
+
+static struct objagg_obj *world_obj_get(struct world *world,
+					struct objagg *objagg,
+					unsigned int key_id)
+{
+	struct objagg_obj *objagg_obj;
+	struct tokey key;
+	int err;
+
+	key.id = key_id;
+	objagg_obj = objagg_obj_get(objagg, &key);
+	if (IS_ERR(objagg_obj)) {
+		pr_err("Key %u: Failed to get object.\n", key_id);
+		return objagg_obj;
+	}
+	if (!world->key_refs[key_id_index(key_id)]) {
+		world->objagg_objs[key_id_index(key_id)] = objagg_obj;
+	} else if (world->objagg_objs[key_id_index(key_id)] != objagg_obj) {
+		pr_err("Key %u: Got another object for the same key.\n",
+		       key_id);
+		err = -EINVAL;
+		goto err_key_id_check;
+	}
+	world->key_refs[key_id_index(key_id)]++;
+	return objagg_obj;
+
+err_key_id_check:
+	objagg_obj_put(objagg, objagg_obj);
+	return ERR_PTR(err);
+}
+
+static void world_obj_put(struct world *world, struct objagg *objagg,
+			  unsigned int key_id)
+{
+	struct objagg_obj *objagg_obj;
+
+	if (!world->key_refs[key_id_index(key_id)])
+		return;
+	objagg_obj = world->objagg_objs[key_id_index(key_id)];
+	objagg_obj_put(objagg, objagg_obj);
+	world->key_refs[key_id_index(key_id)]--;
+}
+
+#define MAX_KEY_ID_DIFF 5
+
+static bool delta_check(void *priv, const void *parent_obj, const void *obj)
+{
+	const struct tokey *parent_key = parent_obj;
+	const struct tokey *key = obj;
+	int diff = key->id - parent_key->id;
+
+	return diff >= 0 && diff <= MAX_KEY_ID_DIFF;
+}
+
+static void *delta_create(void *priv, void *parent_obj, void *obj)
+{
+	struct tokey *parent_key = parent_obj;
+	struct world *world = priv;
+	struct tokey *key = obj;
+	int diff = key->id - parent_key->id;
+	struct delta *delta;
+
+	if (!delta_check(priv, parent_obj, obj))
+		return ERR_PTR(-EINVAL);
+
+	delta = kzalloc_obj(*delta);
+	if (!delta)
+		return ERR_PTR(-ENOMEM);
+	delta->key_id_diff = diff;
+	world->delta_count++;
+	return delta;
+}
+
+static void delta_destroy(void *priv, void *delta_priv)
+{
+	struct delta *delta = delta_priv;
+	struct world *world = priv;
+
+	world->delta_count--;
+	kfree(delta);
+}
+
+static void *root_create(void *priv, void *obj, unsigned int id)
+{
+	struct world *world = priv;
+	struct tokey *key = obj;
+	struct root *root;
+
+	root = kzalloc_obj(*root);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+	memcpy(&root->key, key, sizeof(root->key));
+	memcpy(root->buf, world->next_root_buf, sizeof(root->buf));
+	world->root_count++;
+	return root;
+}
+
+static void root_destroy(void *priv, void *root_priv)
+{
+	struct root *root = root_priv;
+	struct world *world = priv;
+
+	world->root_count--;
+	kfree(root);
+}
+
+static int test_nodelta_obj_get(struct world *world, struct objagg *objagg,
+				unsigned int key_id, bool should_create_root)
+{
+	unsigned int orig_root_count = world->root_count;
+	struct objagg_obj *objagg_obj;
+	const struct root *root;
+	int err;
+
+	if (should_create_root)
+		get_random_bytes(world->next_root_buf,
+			      sizeof(world->next_root_buf));
+
+	objagg_obj = world_obj_get(world, objagg, key_id);
+	if (IS_ERR(objagg_obj)) {
+		pr_err("Key %u: Failed to get object.\n", key_id);
+		return PTR_ERR(objagg_obj);
+	}
+	if (should_create_root) {
+		if (world->root_count != orig_root_count + 1) {
+			pr_err("Key %u: Root was not created\n", key_id);
+			err = -EINVAL;
+			goto err_check_root_count;
+		}
+	} else {
+		if (world->root_count != orig_root_count) {
+			pr_err("Key %u: Root was incorrectly created\n",
+			       key_id);
+			err = -EINVAL;
+			goto err_check_root_count;
+		}
+	}
+	root = objagg_obj_root_priv(objagg_obj);
+	if (root->key.id != key_id) {
+		pr_err("Key %u: Root has unexpected key id\n", key_id);
+		err = -EINVAL;
+		goto err_check_key_id;
+	}
+	if (should_create_root &&
+	    memcmp(world->next_root_buf, root->buf, sizeof(root->buf))) {
+		pr_err("Key %u: Buffer does not match the expected content\n",
+		       key_id);
+		err = -EINVAL;
+		goto err_check_buf;
+	}
+	return 0;
+
+err_check_buf:
+err_check_key_id:
+err_check_root_count:
+	objagg_obj_put(objagg, objagg_obj);
+	return err;
+}
+
+static int test_nodelta_obj_put(struct world *world, struct objagg *objagg,
+				unsigned int key_id, bool should_destroy_root)
+{
+	unsigned int orig_root_count = world->root_count;
+
+	world_obj_put(world, objagg, key_id);
+
+	if (should_destroy_root) {
+		if (world->root_count != orig_root_count - 1) {
+			pr_err("Key %u: Root was not destroyed\n", key_id);
+			return -EINVAL;
+		}
+	} else {
+		if (world->root_count != orig_root_count) {
+			pr_err("Key %u: Root was incorrectly destroyed\n",
+			       key_id);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static int check_stats_zero(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+	int err = 0;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+
+	if (stats->stats_info_count != 0) {
+		pr_err("Stats: Object count is not zero while it should be\n");
+		err = -EINVAL;
+	}
+
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int check_stats_nodelta(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+	int i;
+	int err;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return PTR_ERR(stats);
+
+	if (stats->stats_info_count != NUM_KEYS) {
+		pr_err("Stats: Unexpected object count (%u expected, %u returned)\n",
+		       NUM_KEYS, stats->stats_info_count);
+		err = -EINVAL;
+		goto stats_put;
+	}
+
+	for (i = 0; i < stats->stats_info_count; i++) {
+		if (stats->stats_info[i].stats.user_count != 2) {
+			pr_err("Stats: incorrect user count\n");
+			err = -EINVAL;
+			goto stats_put;
+		}
+		if (stats->stats_info[i].stats.delta_user_count != 2) {
+			pr_err("Stats: incorrect delta user count\n");
+			err = -EINVAL;
+			goto stats_put;
+		}
+	}
+	err = 0;
+
+stats_put:
+	objagg_stats_put(stats);
+	return err;
+}
+
+static bool delta_check_dummy(void *priv, const void *parent_obj,
+			      const void *obj)
+{
+	return false;
+}
+
+static void *delta_create_dummy(void *priv, void *parent_obj, void *obj)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static void delta_destroy_dummy(void *priv, void *delta_priv)
+{
+}
+
+static const struct objagg_ops nodelta_ops = {
+	.obj_size = sizeof(struct tokey),
+	.delta_check = delta_check_dummy,
+	.delta_create = delta_create_dummy,
+	.delta_destroy = delta_destroy_dummy,
+	.root_create = root_create,
+	.root_destroy = root_destroy,
+};
+
+static int test_nodelta(void)
+{
+	struct world world = {};
+	struct objagg *objagg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&nodelta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	err = check_stats_zero(objagg);
+	if (err)
+		goto err_stats_first_zero;
+
+	/* First round of gets, the root objects should be created */
+	for (i = 0; i < NUM_KEYS; i++) {
+		err = test_nodelta_obj_get(&world, objagg, i, true);
+		if (err)
+			goto err_obj_first_get;
+	}
+
+	/* Do the second round of gets, all roots are already created,
+	 * make sure that no new root is created
+	 */
+	for (i = 0; i < NUM_KEYS; i++) {
+		err = test_nodelta_obj_get(&world, objagg, i, false);
+		if (err)
+			goto err_obj_second_get;
+	}
+
+	err = check_stats_nodelta(objagg);
+	if (err)
+		goto err_stats_nodelta;
+
+	for (i = NUM_KEYS - 1; i >= 0; i--) {
+		err = test_nodelta_obj_put(&world, objagg, i, false);
+		if (err)
+			goto err_obj_first_put;
+	}
+	for (i = NUM_KEYS - 1; i >= 0; i--) {
+		err = test_nodelta_obj_put(&world, objagg, i, true);
+		if (err)
+			goto err_obj_second_put;
+	}
+
+	err = check_stats_zero(objagg);
+	if (err)
+		goto err_stats_second_zero;
+
+	objagg_destroy(objagg);
+	return 0;
+
+err_stats_nodelta:
+err_obj_first_put:
+err_obj_second_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, i);
+
+	i = NUM_KEYS;
+err_obj_first_get:
+err_obj_second_put:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, i);
+err_stats_first_zero:
+err_stats_second_zero:
+	objagg_destroy(objagg);
+	return err;
+}
+
+static const struct objagg_ops delta_ops = {
+	.obj_size = sizeof(struct tokey),
+	.delta_check = delta_check,
+	.delta_create = delta_create,
+	.delta_destroy = delta_destroy,
+	.root_create = root_create,
+	.root_destroy = root_destroy,
+};
+
+enum action {
+	ACTION_GET,
+	ACTION_PUT,
+};
+
+enum expect_delta {
+	EXPECT_DELTA_SAME,
+	EXPECT_DELTA_INC,
+	EXPECT_DELTA_DEC,
+};
+
+enum expect_root {
+	EXPECT_ROOT_SAME,
+	EXPECT_ROOT_INC,
+	EXPECT_ROOT_DEC,
+};
+
+struct expect_stats_info {
+	struct objagg_obj_stats stats;
+	bool is_root;
+	unsigned int key_id;
+};
+
+struct expect_stats {
+	unsigned int info_count;
+	struct expect_stats_info info[NUM_KEYS];
+};
+
+struct action_item {
+	unsigned int key_id;
+	enum action action;
+	enum expect_delta expect_delta;
+	enum expect_root expect_root;
+	struct expect_stats expect_stats;
+};
+
+#define EXPECT_STATS(count, ...)		\
+{						\
+	.info_count = count,			\
+	.info = { __VA_ARGS__ }			\
+}
+
+#define ROOT(key_id, user_count, delta_user_count)	\
+	{{user_count, delta_user_count}, true, key_id}
+
+#define DELTA(key_id, user_count)			\
+	{{user_count, user_count}, false, key_id}
+
+static const struct action_item action_items[] = {
+	{
+		1, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(1, ROOT(1, 1, 1)),
+	},	/* r: 1			d: */
+	{
+		7, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(2, ROOT(1, 1, 1), ROOT(7, 1, 1)),
+	},	/* r: 1, 7		d: */
+	{
+		3, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(3, ROOT(1, 1, 2), ROOT(7, 1, 1),
+				DELTA(3, 1)),
+	},	/* r: 1, 7		d: 3^1 */
+	{
+		5, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 1, 3), ROOT(7, 1, 1),
+				DELTA(3, 1), DELTA(5, 1)),
+	},	/* r: 1, 7		d: 3^1, 5^1 */
+	{
+		3, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 1, 4), ROOT(7, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 7		d: 3^1, 3^1, 5^1 */
+	{
+		1, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(1, 2, 5), ROOT(7, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7		d: 3^1, 3^1, 5^1 */
+	{
+		30, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(5, ROOT(1, 2, 5), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 5), ROOT(7, 1, 2), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(5, 1), DELTA(8, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1, 8^7 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 5), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(3, 2), DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 3^1, 5^1, 8^7, 8^7 */
+	{
+		3, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(6, ROOT(1, 2, 4), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(3, 1), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 3^1, 5^1, 8^7, 8^7 */
+	{
+		3, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(1, 2, 3), ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 1, 7, 30	d: 5^1, 8^7, 8^7 */
+	{
+		1, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(1, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 1, 7, 30		d: 5^1, 8^7, 8^7 */
+	{
+		1, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(30, 1, 1), ROOT(1, 0, 1),
+				DELTA(8, 2), DELTA(5, 1)),
+	},	/* r: 7, 30		d: 5^1, 8^7, 8^7 */
+	{
+		5, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_DEC,
+		EXPECT_STATS(3, ROOT(7, 1, 3), ROOT(30, 1, 1),
+				DELTA(8, 2)),
+	},	/* r: 7, 30		d: 8^7, 8^7 */
+	{
+		5, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_INC,
+		EXPECT_STATS(4, ROOT(7, 1, 3), ROOT(30, 1, 1), ROOT(5, 1, 1),
+				DELTA(8, 2)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7 */
+	{
+		6, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 4), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 3), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 2), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(7, 1, 2), ROOT(5, 1, 2), ROOT(30, 1, 1),
+				DELTA(8, 1), DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 8^7, 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(4, ROOT(5, 1, 2), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(6, 1)),
+	},	/* r: 7, 30, 5		d: 6^5 */
+	{
+		8, ACTION_GET, EXPECT_DELTA_INC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(5, ROOT(5, 1, 3), ROOT(7, 1, 1), ROOT(30, 1, 1),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 7, 30, 5		d: 6^5, 8^5 */
+	{
+		7, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_DEC,
+		EXPECT_STATS(4, ROOT(5, 1, 3), ROOT(30, 1, 1),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 30, 5		d: 6^5, 8^5 */
+	{
+		30, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_DEC,
+		EXPECT_STATS(3, ROOT(5, 1, 3),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r: 5			d: 6^5, 8^5 */
+	{
+		5, ACTION_PUT, EXPECT_DELTA_SAME, EXPECT_ROOT_SAME,
+		EXPECT_STATS(3, ROOT(5, 0, 2),
+				DELTA(6, 1), DELTA(8, 1)),
+	},	/* r:			d: 6^5, 8^5 */
+	{
+		6, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_SAME,
+		EXPECT_STATS(2, ROOT(5, 0, 1),
+				DELTA(8, 1)),
+	},	/* r:			d: 6^5 */
+	{
+		8, ACTION_PUT, EXPECT_DELTA_DEC, EXPECT_ROOT_DEC,
+		EXPECT_STATS(0, ),
+	},	/* r:			d: */
+};
+
+static int check_expect(struct world *world,
+			const struct action_item *action_item,
+			unsigned int orig_delta_count,
+			unsigned int orig_root_count)
+{
+	unsigned int key_id = action_item->key_id;
+
+	switch (action_item->expect_delta) {
+	case EXPECT_DELTA_SAME:
+		if (orig_delta_count != world->delta_count) {
+			pr_err("Key %u: Delta count changed while expected to remain the same.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_DELTA_INC:
+		if (WARN_ON(action_item->action == ACTION_PUT))
+			return -EINVAL;
+		if (orig_delta_count + 1 != world->delta_count) {
+			pr_err("Key %u: Delta count was not incremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_DELTA_DEC:
+		if (WARN_ON(action_item->action == ACTION_GET))
+			return -EINVAL;
+		if (orig_delta_count - 1 != world->delta_count) {
+			pr_err("Key %u: Delta count was not decremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	}
+
+	switch (action_item->expect_root) {
+	case EXPECT_ROOT_SAME:
+		if (orig_root_count != world->root_count) {
+			pr_err("Key %u: Root count changed while expected to remain the same.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_ROOT_INC:
+		if (WARN_ON(action_item->action == ACTION_PUT))
+			return -EINVAL;
+		if (orig_root_count + 1 != world->root_count) {
+			pr_err("Key %u: Root count was not incremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+		break;
+	case EXPECT_ROOT_DEC:
+		if (WARN_ON(action_item->action == ACTION_GET))
+			return -EINVAL;
+		if (orig_root_count - 1 != world->root_count) {
+			pr_err("Key %u: Root count was not decremented.\n",
+			       key_id);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static unsigned int obj_to_key_id(struct objagg_obj *objagg_obj)
+{
+	const struct tokey *root_key;
+	const struct delta *delta;
+	unsigned int key_id;
+
+	root_key = objagg_obj_root_priv(objagg_obj);
+	key_id = root_key->id;
+	delta = objagg_obj_delta_priv(objagg_obj);
+	if (delta)
+		key_id += delta->key_id_diff;
+	return key_id;
+}
+
+static int
+check_expect_stats_nums(const struct objagg_obj_stats_info *stats_info,
+			const struct expect_stats_info *expect_stats_info,
+			const char **errmsg)
+{
+	if (stats_info->is_root != expect_stats_info->is_root) {
+		if (errmsg)
+			*errmsg = "Incorrect root/delta indication";
+		return -EINVAL;
+	}
+	if (stats_info->stats.user_count !=
+	    expect_stats_info->stats.user_count) {
+		if (errmsg)
+			*errmsg = "Incorrect user count";
+		return -EINVAL;
+	}
+	if (stats_info->stats.delta_user_count !=
+	    expect_stats_info->stats.delta_user_count) {
+		if (errmsg)
+			*errmsg = "Incorrect delta user count";
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
+check_expect_stats_key_id(const struct objagg_obj_stats_info *stats_info,
+			  const struct expect_stats_info *expect_stats_info,
+			  const char **errmsg)
+{
+	if (obj_to_key_id(stats_info->objagg_obj) !=
+	    expect_stats_info->key_id) {
+		if (errmsg)
+			*errmsg = "incorrect key id";
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int check_expect_stats_neigh(const struct objagg_stats *stats,
+				    const struct expect_stats *expect_stats,
+				    int pos)
+{
+	int i;
+	int err;
+
+	for (i = pos - 1; i >= 0; i--) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[pos], NULL);
+		if (err)
+			break;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[pos], NULL);
+		if (!err)
+			return 0;
+	}
+	for (i = pos + 1; i < stats->stats_info_count; i++) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[pos], NULL);
+		if (err)
+			break;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[pos], NULL);
+		if (!err)
+			return 0;
+	}
+	return -EINVAL;
+}
+
+static int __check_expect_stats(const struct objagg_stats *stats,
+				const struct expect_stats *expect_stats,
+				const char **errmsg)
+{
+	int i;
+	int err;
+
+	if (stats->stats_info_count != expect_stats->info_count) {
+		*errmsg = "Unexpected object count";
+		return -EINVAL;
+	}
+
+	for (i = 0; i < stats->stats_info_count; i++) {
+		err = check_expect_stats_nums(&stats->stats_info[i],
+					      &expect_stats->info[i], errmsg);
+		if (err)
+			return err;
+		err = check_expect_stats_key_id(&stats->stats_info[i],
+						&expect_stats->info[i], errmsg);
+		if (err) {
+			/* It is possible that one of the neighbor stats with
+			 * same numbers have the correct key id, so check it
+			 */
+			err = check_expect_stats_neigh(stats, expect_stats, i);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+static int check_expect_stats(struct objagg *objagg,
+			      const struct expect_stats *expect_stats,
+			      const char **errmsg)
+{
+	const struct objagg_stats *stats;
+	int err;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats)) {
+		*errmsg = "objagg_stats_get() failed.";
+		return PTR_ERR(stats);
+	}
+	err = __check_expect_stats(stats, expect_stats, errmsg);
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int test_delta_action_item(struct world *world,
+				  struct objagg *objagg,
+				  const struct action_item *action_item,
+				  bool inverse)
+{
+	unsigned int orig_delta_count = world->delta_count;
+	unsigned int orig_root_count = world->root_count;
+	unsigned int key_id = action_item->key_id;
+	enum action action = action_item->action;
+	struct objagg_obj *objagg_obj;
+	const char *errmsg;
+	int err;
+
+	if (inverse)
+		action = action == ACTION_GET ? ACTION_PUT : ACTION_GET;
+
+	switch (action) {
+	case ACTION_GET:
+		objagg_obj = world_obj_get(world, objagg, key_id);
+		if (IS_ERR(objagg_obj))
+			return PTR_ERR(objagg_obj);
+		break;
+	case ACTION_PUT:
+		world_obj_put(world, objagg, key_id);
+		break;
+	}
+
+	if (inverse)
+		return 0;
+	err = check_expect(world, action_item,
+			   orig_delta_count, orig_root_count);
+	if (err)
+		goto errout;
+
+	err = check_expect_stats(objagg, &action_item->expect_stats, &errmsg);
+	if (err) {
+		pr_err("Key %u: Stats: %s\n", action_item->key_id, errmsg);
+		goto errout;
+	}
+
+	return 0;
+
+errout:
+	/* This can only happen when action is not inversed.
+	 * So in case of an error, cleanup by doing inverse action.
+	 */
+	test_delta_action_item(world, objagg, action_item, true);
+	return err;
+}
+
+static int test_delta(void)
+{
+	struct world world = {};
+	struct objagg *objagg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&delta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	for (i = 0; i < ARRAY_SIZE(action_items); i++) {
+		err = test_delta_action_item(&world, objagg,
+					     &action_items[i], false);
+		if (err)
+			goto err_do_action_item;
+	}
+
+	objagg_destroy(objagg);
+	return 0;
+
+err_do_action_item:
+	for (i--; i >= 0; i--)
+		test_delta_action_item(&world, objagg, &action_items[i], true);
+
+	objagg_destroy(objagg);
+	return err;
+}
+
+struct hints_case {
+	const unsigned int *key_ids;
+	size_t key_ids_count;
+	struct expect_stats expect_stats;
+	struct expect_stats expect_stats_hints;
+};
+
+static const unsigned int hints_case_key_ids[] = {
+	1, 7, 3, 5, 3, 1, 30, 8, 8, 5, 6, 8,
+};
+
+static const struct hints_case hints_case = {
+	.key_ids = hints_case_key_ids,
+	.key_ids_count = ARRAY_SIZE(hints_case_key_ids),
+	.expect_stats =
+		EXPECT_STATS(7, ROOT(1, 2, 7), ROOT(7, 1, 4), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(3, 2),
+				DELTA(5, 2), DELTA(6, 1)),
+	.expect_stats_hints =
+		EXPECT_STATS(7, ROOT(3, 2, 9), ROOT(1, 2, 2), ROOT(30, 1, 1),
+				DELTA(8, 3), DELTA(5, 2),
+				DELTA(6, 1), DELTA(7, 1)),
+};
+
+static void __pr_debug_stats(const struct objagg_stats *stats)
+{
+	int i;
+
+	for (i = 0; i < stats->stats_info_count; i++)
+		pr_debug("Stat index %d key %u: u %d, d %d, %s\n", i,
+			 obj_to_key_id(stats->stats_info[i].objagg_obj),
+			 stats->stats_info[i].stats.user_count,
+			 stats->stats_info[i].stats.delta_user_count,
+			 stats->stats_info[i].is_root ? "root" : "noroot");
+}
+
+static void pr_debug_stats(struct objagg *objagg)
+{
+	const struct objagg_stats *stats;
+
+	stats = objagg_stats_get(objagg);
+	if (IS_ERR(stats))
+		return;
+	__pr_debug_stats(stats);
+	objagg_stats_put(stats);
+}
+
+static void pr_debug_hints_stats(struct objagg_hints *objagg_hints)
+{
+	const struct objagg_stats *stats;
+
+	stats = objagg_hints_stats_get(objagg_hints);
+	if (IS_ERR(stats))
+		return;
+	__pr_debug_stats(stats);
+	objagg_stats_put(stats);
+}
+
+static int check_expect_hints_stats(struct objagg_hints *objagg_hints,
+				    const struct expect_stats *expect_stats,
+				    const char **errmsg)
+{
+	const struct objagg_stats *stats;
+	int err;
+
+	stats = objagg_hints_stats_get(objagg_hints);
+	if (IS_ERR(stats)) {
+		*errmsg = "objagg_hints_stats_get() failed.";
+		return PTR_ERR(stats);
+	}
+	err = __check_expect_stats(stats, expect_stats, errmsg);
+	objagg_stats_put(stats);
+	return err;
+}
+
+static int test_hints_case2(const struct hints_case *hints_case,
+			    struct objagg_hints *hints, struct objagg *objagg)
+{
+	struct objagg_obj *objagg_obj;
+	struct world world2 = {};
+	struct objagg *objagg2;
+	const char *errmsg;
+	int i;
+	int err;
+
+	pr_debug_hints_stats(hints);
+	err = check_expect_hints_stats(hints, &hints_case->expect_stats_hints,
+				       &errmsg);
+	if (err) {
+		pr_err("Hints stats: %s\n", errmsg);
+		return err;
+	}
+
+	objagg2 = objagg_create(&delta_ops, hints, &world2);
+	if (IS_ERR(objagg2))
+		return PTR_ERR(objagg2);
+
+	for (i = 0; i < hints_case->key_ids_count; i++) {
+		objagg_obj = world_obj_get(&world2, objagg2,
+					   hints_case->key_ids[i]);
+		if (IS_ERR(objagg_obj)) {
+			err = PTR_ERR(objagg_obj);
+			goto err_world2_obj_get;
+		}
+	}
+
+	pr_debug_stats(objagg2);
+	err = check_expect_stats(objagg2, &hints_case->expect_stats_hints,
+				 &errmsg);
+	if (err) {
+		pr_err("Stats2: %s\n", errmsg);
+		goto err_check_expect_stats2;
+	}
+
+	err = 0;
+
+err_check_expect_stats2:
+err_world2_obj_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world2, objagg, hints_case->key_ids[i]);
+	i = hints_case->key_ids_count;
+	objagg_destroy(objagg2);
+
+	return err;
+}
+
+static int test_hints_case(const struct hints_case *hints_case)
+{
+	struct objagg_obj *objagg_obj;
+	struct objagg_hints *hints;
+	struct world world = {};
+	struct objagg *objagg;
+	const char *errmsg;
+	int i;
+	int err;
+
+	objagg = objagg_create(&delta_ops, NULL, &world);
+	if (IS_ERR(objagg))
+		return PTR_ERR(objagg);
+
+	for (i = 0; i < hints_case->key_ids_count; i++) {
+		objagg_obj = world_obj_get(&world, objagg,
+					   hints_case->key_ids[i]);
+		if (IS_ERR(objagg_obj)) {
+			err = PTR_ERR(objagg_obj);
+			goto err_world_obj_get;
+		}
+	}
+
+	pr_debug_stats(objagg);
+	err = check_expect_stats(objagg, &hints_case->expect_stats, &errmsg);
+	if (err) {
+		pr_err("Stats: %s\n", errmsg);
+		goto err_check_expect_stats;
+	}
+
+	hints = objagg_hints_get(objagg, OBJAGG_OPT_ALGO_SIMPLE_GREEDY);
+	if (IS_ERR(hints)) {
+		err = PTR_ERR(hints);
+		goto err_hints_get;
+	}
+
+	err = test_hints_case2(hints_case, hints, objagg);
+
+	objagg_hints_put(hints);
+err_hints_get:
+err_check_expect_stats:
+err_world_obj_get:
+	for (i--; i >= 0; i--)
+		world_obj_put(&world, objagg, hints_case->key_ids[i]);
+
+	objagg_destroy(objagg);
+	return err;
+}
+static int test_hints(void)
+{
+	return test_hints_case(&hints_case);
+}
+
+static int __init test_objagg_init(void)
+{
+	int err;
+
+	err = test_nodelta();
+	if (err)
+		return err;
+	err = test_delta();
+	if (err)
+		return err;
+	return test_hints();
+}
+
+static void __exit test_objagg_exit(void)
+{
+}
+
+module_init(test_objagg_init);
+module_exit(test_objagg_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
+MODULE_DESCRIPTION("Test module for objagg");