lib: introduce initial implementation of object aggregation manager

This lib tracks objects which could be of two types:
1) root object
2) nested object - with a "delta" which differentiates it from
                   the associated root object
The objects are tracked by a hashtable and reference-counted. User is
responsible of implementing callbacks to create/destroy root entity
related to each root object and callback to create/destroy nested object
delta.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 835 insertions, 0 deletions

diff --git a/lib/test_objagg.c b/lib/test_objagg.c
new file mode 100644
index 000000000000..aac5d8e8800c
--- /dev/null
+++ b/lib/test_objagg.c
@@ -0,0 +1,835 @@
+// 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: God 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 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 (diff < 0 || diff > MAX_KEY_ID_DIFF)
+                return ERR_PTR(-EINVAL);
+
+        delta = kzalloc(sizeof(*delta), GFP_KERNEL);
+        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)
+{
+        struct world *world = priv;
+        struct tokey *key = obj;
+        struct root *root;
+
+        root = kzalloc(sizeof(*root), GFP_KERNEL);
+        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)
+                prandom_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 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_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, &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_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))
+                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, &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;
+}
+
+static int __init test_objagg_init(void)
+{
+        int err;
+
+        err = test_nodelta();
+        if (err)
+                return err;
+        return test_delta();
+}
+
+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");