Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 828 insertions, 0 deletions

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
new file mode 100644
index 000000000..76c607ee6
--- /dev/null
+++ b/lib/test_rhashtable.c
@@ -0,0 +1,828 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Resizable, Scalable, Concurrent Hash Table
+ *
+ * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
+ * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
+ */
+
+/**************************************************************************
+ * Self Test
+ **************************************************************************/
+
+#include <linux/init.h>
+#include <linux/jhash.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/rcupdate.h>
+#include <linux/rhashtable.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/random.h>
+#include <linux/vmalloc.h>
+#include <linux/wait.h>
+
+#define MAX_ENTRIES	1000000
+#define TEST_INSERT_FAIL INT_MAX
+
+static int parm_entries = 50000;
+module_param(parm_entries, int, 0);
+MODULE_PARM_DESC(parm_entries, "Number of entries to add (default: 50000)");
+
+static int runs = 4;
+module_param(runs, int, 0);
+MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
+
+static int max_size = 0;
+module_param(max_size, int, 0);
+MODULE_PARM_DESC(max_size, "Maximum table size (default: calculated)");
+
+static bool shrinking = false;
+module_param(shrinking, bool, 0);
+MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
+
+static int size = 8;
+module_param(size, int, 0);
+MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
+
+static int tcount = 10;
+module_param(tcount, int, 0);
+MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
+
+static bool enomem_retry = false;
+module_param(enomem_retry, bool, 0);
+MODULE_PARM_DESC(enomem_retry, "Retry insert even if -ENOMEM was returned (default: off)");
+
+struct test_obj_val {
+	int	id;
+	int	tid;
+};
+
+struct test_obj {
+	struct test_obj_val	value;
+	struct rhash_head	node;
+};
+
+struct test_obj_rhl {
+	struct test_obj_val	value;
+	struct rhlist_head	list_node;
+};
+
+struct thread_data {
+	unsigned int entries;
+	int id;
+	struct task_struct *task;
+	struct test_obj *objs;
+};
+
+static u32 my_hashfn(const void *data, u32 len, u32 seed)
+{
+	const struct test_obj_rhl *obj = data;
+
+	return (obj->value.id % 10);
+}
+
+static int my_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct test_obj_rhl *test_obj = obj;
+	const struct test_obj_val *val = arg->key;
+
+	return test_obj->value.id - val->id;
+}
+
+static struct rhashtable_params test_rht_params = {
+	.head_offset = offsetof(struct test_obj, node),
+	.key_offset = offsetof(struct test_obj, value),
+	.key_len = sizeof(struct test_obj_val),
+	.hashfn = jhash,
+};
+
+static struct rhashtable_params test_rht_params_dup = {
+	.head_offset = offsetof(struct test_obj_rhl, list_node),
+	.key_offset = offsetof(struct test_obj_rhl, value),
+	.key_len = sizeof(struct test_obj_val),
+	.hashfn = jhash,
+	.obj_hashfn = my_hashfn,
+	.obj_cmpfn = my_cmpfn,
+	.nelem_hint = 128,
+	.automatic_shrinking = false,
+};
+
+static atomic_t startup_count;
+static DECLARE_WAIT_QUEUE_HEAD(startup_wait);
+
+static int insert_retry(struct rhashtable *ht, struct test_obj *obj,
+                        const struct rhashtable_params params)
+{
+	int err, retries = -1, enomem_retries = 0;
+
+	do {
+		retries++;
+		cond_resched();
+		err = rhashtable_insert_fast(ht, &obj->node, params);
+		if (err == -ENOMEM && enomem_retry) {
+			enomem_retries++;
+			err = -EBUSY;
+		}
+	} while (err == -EBUSY);
+
+	if (enomem_retries)
+		pr_info(" %u insertions retried after -ENOMEM\n",
+			enomem_retries);
+
+	return err ? : retries;
+}
+
+static int __init test_rht_lookup(struct rhashtable *ht, struct test_obj *array,
+				  unsigned int entries)
+{
+	unsigned int i;
+
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj;
+		bool expected = !(i % 2);
+		struct test_obj_val key = {
+			.id = i,
+		};
+
+		if (array[i / 2].value.id == TEST_INSERT_FAIL)
+			expected = false;
+
+		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
+
+		if (expected && !obj) {
+			pr_warn("Test failed: Could not find key %u\n", key.id);
+			return -ENOENT;
+		} else if (!expected && obj) {
+			pr_warn("Test failed: Unexpected entry found for key %u\n",
+				key.id);
+			return -EEXIST;
+		} else if (expected && obj) {
+			if (obj->value.id != i) {
+				pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
+					obj->value.id, i);
+				return -EINVAL;
+			}
+		}
+
+		cond_resched_rcu();
+	}
+
+	return 0;
+}
+
+static void test_bucket_stats(struct rhashtable *ht, unsigned int entries)
+{
+	unsigned int total = 0, chain_len = 0;
+	struct rhashtable_iter hti;
+	struct rhash_head *pos;
+
+	rhashtable_walk_enter(ht, &hti);
+	rhashtable_walk_start(&hti);
+
+	while ((pos = rhashtable_walk_next(&hti))) {
+		if (PTR_ERR(pos) == -EAGAIN) {
+			pr_info("Info: encountered resize\n");
+			chain_len++;
+			continue;
+		} else if (IS_ERR(pos)) {
+			pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
+				PTR_ERR(pos));
+			break;
+		}
+
+		total++;
+	}
+
+	rhashtable_walk_stop(&hti);
+	rhashtable_walk_exit(&hti);
+
+	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
+		total, atomic_read(&ht->nelems), entries, chain_len);
+
+	if (total != atomic_read(&ht->nelems) || total != entries)
+		pr_warn("Test failed: Total count mismatch ^^^");
+}
+
+static s64 __init test_rhashtable(struct rhashtable *ht, struct test_obj *array,
+				  unsigned int entries)
+{
+	struct test_obj *obj;
+	int err;
+	unsigned int i, insert_retries = 0;
+	s64 start, end;
+
+	/*
+	 * Insertion Test:
+	 * Insert entries into table with all keys even numbers
+	 */
+	pr_info("  Adding %d keys\n", entries);
+	start = ktime_get_ns();
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj = &array[i];
+
+		obj->value.id = i * 2;
+		err = insert_retry(ht, obj, test_rht_params);
+		if (err > 0)
+			insert_retries += err;
+		else if (err)
+			return err;
+	}
+
+	if (insert_retries)
+		pr_info("  %u insertions retried due to memory pressure\n",
+			insert_retries);
+
+	test_bucket_stats(ht, entries);
+	rcu_read_lock();
+	test_rht_lookup(ht, array, entries);
+	rcu_read_unlock();
+
+	test_bucket_stats(ht, entries);
+
+	pr_info("  Deleting %d keys\n", entries);
+	for (i = 0; i < entries; i++) {
+		struct test_obj_val key = {
+			.id = i * 2,
+		};
+
+		if (array[i].value.id != TEST_INSERT_FAIL) {
+			obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
+			BUG_ON(!obj);
+
+			rhashtable_remove_fast(ht, &obj->node, test_rht_params);
+		}
+
+		cond_resched();
+	}
+
+	end = ktime_get_ns();
+	pr_info("  Duration of test: %lld ns\n", end - start);
+
+	return end - start;
+}
+
+static struct rhashtable ht;
+static struct rhltable rhlt;
+
+static int __init test_rhltable(unsigned int entries)
+{
+	struct test_obj_rhl *rhl_test_objects;
+	unsigned long *obj_in_table;
+	unsigned int i, j, k;
+	int ret, err;
+
+	if (entries == 0)
+		entries = 1;
+
+	rhl_test_objects = vzalloc(array_size(entries,
+					      sizeof(*rhl_test_objects)));
+	if (!rhl_test_objects)
+		return -ENOMEM;
+
+	ret = -ENOMEM;
+	obj_in_table = vzalloc(array_size(sizeof(unsigned long),
+					  BITS_TO_LONGS(entries)));
+	if (!obj_in_table)
+		goto out_free;
+
+	err = rhltable_init(&rhlt, &test_rht_params);
+	if (WARN_ON(err))
+		goto out_free;
+
+	k = prandom_u32();
+	ret = 0;
+	for (i = 0; i < entries; i++) {
+		rhl_test_objects[i].value.id = k;
+		err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node,
+				      test_rht_params);
+		if (WARN(err, "error %d on element %d\n", err, i))
+			break;
+		if (err == 0)
+			set_bit(i, obj_in_table);
+	}
+
+	if (err)
+		ret = err;
+
+	pr_info("test %d add/delete pairs into rhlist\n", entries);
+	for (i = 0; i < entries; i++) {
+		struct rhlist_head *h, *pos;
+		struct test_obj_rhl *obj;
+		struct test_obj_val key = {
+			.id = k,
+		};
+		bool found;
+
+		rcu_read_lock();
+		h = rhltable_lookup(&rhlt, &key, test_rht_params);
+		if (WARN(!h, "key not found during iteration %d of %d", i, entries)) {
+			rcu_read_unlock();
+			break;
+		}
+
+		if (i) {
+			j = i - 1;
+			rhl_for_each_entry_rcu(obj, pos, h, list_node) {
+				if (WARN(pos == &rhl_test_objects[j].list_node, "old element found, should be gone"))
+					break;
+			}
+		}
+
+		cond_resched_rcu();
+
+		found = false;
+
+		rhl_for_each_entry_rcu(obj, pos, h, list_node) {
+			if (pos == &rhl_test_objects[i].list_node) {
+				found = true;
+				break;
+			}
+		}
+
+		rcu_read_unlock();
+
+		if (WARN(!found, "element %d not found", i))
+			break;
+
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		WARN(err, "rhltable_remove: err %d for iteration %d\n", err, i);
+		if (err == 0)
+			clear_bit(i, obj_in_table);
+	}
+
+	if (ret == 0 && err)
+		ret = err;
+
+	for (i = 0; i < entries; i++) {
+		WARN(test_bit(i, obj_in_table), "elem %d allegedly still present", i);
+
+		err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node,
+				      test_rht_params);
+		if (WARN(err, "error %d on element %d\n", err, i))
+			break;
+		if (err == 0)
+			set_bit(i, obj_in_table);
+	}
+
+	pr_info("test %d random rhlist add/delete operations\n", entries);
+	for (j = 0; j < entries; j++) {
+		u32 i = prandom_u32_max(entries);
+		u32 prand = prandom_u32();
+
+		cond_resched();
+
+		if (prand == 0)
+			prand = prandom_u32();
+
+		if (prand & 1) {
+			prand >>= 1;
+			continue;
+		}
+
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		if (test_bit(i, obj_in_table)) {
+			clear_bit(i, obj_in_table);
+			if (WARN(err, "cannot remove element at slot %d", i))
+				continue;
+		} else {
+			if (WARN(err != -ENOENT, "removed non-existent element %d, error %d not %d",
+			     i, err, -ENOENT))
+				continue;
+		}
+
+		if (prand & 1) {
+			prand >>= 1;
+			continue;
+		}
+
+		err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		if (err == 0) {
+			if (WARN(test_and_set_bit(i, obj_in_table), "succeeded to insert same object %d", i))
+				continue;
+		} else {
+			if (WARN(!test_bit(i, obj_in_table), "failed to insert object %d", i))
+				continue;
+		}
+
+		if (prand & 1) {
+			prand >>= 1;
+			continue;
+		}
+
+		i = prandom_u32_max(entries);
+		if (test_bit(i, obj_in_table)) {
+			err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+			WARN(err, "cannot remove element at slot %d", i);
+			if (err == 0)
+				clear_bit(i, obj_in_table);
+		} else {
+			err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+			WARN(err, "failed to insert object %d", i);
+			if (err == 0)
+				set_bit(i, obj_in_table);
+		}
+	}
+
+	for (i = 0; i < entries; i++) {
+		cond_resched();
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		if (test_bit(i, obj_in_table)) {
+			if (WARN(err, "cannot remove element at slot %d", i))
+				continue;
+		} else {
+			if (WARN(err != -ENOENT, "removed non-existent element, error %d not %d",
+				 err, -ENOENT))
+				continue;
+		}
+	}
+
+	rhltable_destroy(&rhlt);
+out_free:
+	vfree(rhl_test_objects);
+	vfree(obj_in_table);
+	return ret;
+}
+
+static int __init test_rhashtable_max(struct test_obj *array,
+				      unsigned int entries)
+{
+	unsigned int i, insert_retries = 0;
+	int err;
+
+	test_rht_params.max_size = roundup_pow_of_two(entries / 8);
+	err = rhashtable_init(&ht, &test_rht_params);
+	if (err)
+		return err;
+
+	for (i = 0; i < ht.max_elems; i++) {
+		struct test_obj *obj = &array[i];
+
+		obj->value.id = i * 2;
+		err = insert_retry(&ht, obj, test_rht_params);
+		if (err > 0)
+			insert_retries += err;
+		else if (err)
+			return err;
+	}
+
+	err = insert_retry(&ht, &array[ht.max_elems], test_rht_params);
+	if (err == -E2BIG) {
+		err = 0;
+	} else {
+		pr_info("insert element %u should have failed with %d, got %d\n",
+				ht.max_elems, -E2BIG, err);
+		if (err == 0)
+			err = -1;
+	}
+
+	rhashtable_destroy(&ht);
+
+	return err;
+}
+
+static unsigned int __init print_ht(struct rhltable *rhlt)
+{
+	struct rhashtable *ht;
+	const struct bucket_table *tbl;
+	char buff[512] = "";
+	unsigned int i, cnt = 0;
+
+	ht = &rhlt->ht;
+	/* Take the mutex to avoid RCU warning */
+	mutex_lock(&ht->mutex);
+	tbl = rht_dereference(ht->tbl, ht);
+	for (i = 0; i < tbl->size; i++) {
+		struct rhash_head *pos, *next;
+		struct test_obj_rhl *p;
+
+		pos = rht_ptr_exclusive(tbl->buckets + i);
+		next = !rht_is_a_nulls(pos) ? rht_dereference(pos->next, ht) : NULL;
+
+		if (!rht_is_a_nulls(pos)) {
+			sprintf(buff, "%s\nbucket[%d] -> ", buff, i);
+		}
+
+		while (!rht_is_a_nulls(pos)) {
+			struct rhlist_head *list = container_of(pos, struct rhlist_head, rhead);
+			sprintf(buff, "%s[[", buff);
+			do {
+				pos = &list->rhead;
+				list = rht_dereference(list->next, ht);
+				p = rht_obj(ht, pos);
+
+				sprintf(buff, "%s val %d (tid=%d)%s", buff, p->value.id, p->value.tid,
+					list? ", " : " ");
+				cnt++;
+			} while (list);
+
+			pos = next,
+			next = !rht_is_a_nulls(pos) ?
+				rht_dereference(pos->next, ht) : NULL;
+
+			sprintf(buff, "%s]]%s", buff, !rht_is_a_nulls(pos) ? " -> " : "");
+		}
+	}
+	printk(KERN_ERR "\n---- ht: ----%s\n-------------\n", buff);
+	mutex_unlock(&ht->mutex);
+
+	return cnt;
+}
+
+static int __init test_insert_dup(struct test_obj_rhl *rhl_test_objects,
+				  int cnt, bool slow)
+{
+	struct rhltable *rhlt;
+	unsigned int i, ret;
+	const char *key;
+	int err = 0;
+
+	rhlt = kmalloc(sizeof(*rhlt), GFP_KERNEL);
+	if (WARN_ON(!rhlt))
+		return -EINVAL;
+
+	err = rhltable_init(rhlt, &test_rht_params_dup);
+	if (WARN_ON(err)) {
+		kfree(rhlt);
+		return err;
+	}
+
+	for (i = 0; i < cnt; i++) {
+		rhl_test_objects[i].value.tid = i;
+		key = rht_obj(&rhlt->ht, &rhl_test_objects[i].list_node.rhead);
+		key += test_rht_params_dup.key_offset;
+
+		if (slow) {
+			err = PTR_ERR(rhashtable_insert_slow(&rhlt->ht, key,
+							     &rhl_test_objects[i].list_node.rhead));
+			if (err == -EAGAIN)
+				err = 0;
+		} else
+			err = rhltable_insert(rhlt,
+					      &rhl_test_objects[i].list_node,
+					      test_rht_params_dup);
+		if (WARN(err, "error %d on element %d/%d (%s)\n", err, i, cnt, slow? "slow" : "fast"))
+			goto skip_print;
+	}
+
+	ret = print_ht(rhlt);
+	WARN(ret != cnt, "missing rhltable elements (%d != %d, %s)\n", ret, cnt, slow? "slow" : "fast");
+
+skip_print:
+	rhltable_destroy(rhlt);
+	kfree(rhlt);
+
+	return 0;
+}
+
+static int __init test_insert_duplicates_run(void)
+{
+	struct test_obj_rhl rhl_test_objects[3] = {};
+
+	pr_info("test inserting duplicates\n");
+
+	/* two different values that map to same bucket */
+	rhl_test_objects[0].value.id = 1;
+	rhl_test_objects[1].value.id = 21;
+
+	/* and another duplicate with same as [0] value
+	 * which will be second on the bucket list */
+	rhl_test_objects[2].value.id = rhl_test_objects[0].value.id;
+
+	test_insert_dup(rhl_test_objects, 2, false);
+	test_insert_dup(rhl_test_objects, 3, false);
+	test_insert_dup(rhl_test_objects, 2, true);
+	test_insert_dup(rhl_test_objects, 3, true);
+
+	return 0;
+}
+
+static int thread_lookup_test(struct thread_data *tdata)
+{
+	unsigned int entries = tdata->entries;
+	int i, err = 0;
+
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj;
+		struct test_obj_val key = {
+			.id = i,
+			.tid = tdata->id,
+		};
+
+		obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
+		if (obj && (tdata->objs[i].value.id == TEST_INSERT_FAIL)) {
+			pr_err("  found unexpected object %d-%d\n", key.tid, key.id);
+			err++;
+		} else if (!obj && (tdata->objs[i].value.id != TEST_INSERT_FAIL)) {
+			pr_err("  object %d-%d not found!\n", key.tid, key.id);
+			err++;
+		} else if (obj && memcmp(&obj->value, &key, sizeof(key))) {
+			pr_err("  wrong object returned (got %d-%d, expected %d-%d)\n",
+			       obj->value.tid, obj->value.id, key.tid, key.id);
+			err++;
+		}
+
+		cond_resched();
+	}
+	return err;
+}
+
+static int threadfunc(void *data)
+{
+	int i, step, err = 0, insert_retries = 0;
+	struct thread_data *tdata = data;
+
+	if (atomic_dec_and_test(&startup_count))
+		wake_up(&startup_wait);
+	if (wait_event_interruptible(startup_wait, atomic_read(&startup_count) == -1)) {
+		pr_err("  thread[%d]: interrupted\n", tdata->id);
+		goto out;
+	}
+
+	for (i = 0; i < tdata->entries; i++) {
+		tdata->objs[i].value.id = i;
+		tdata->objs[i].value.tid = tdata->id;
+		err = insert_retry(&ht, &tdata->objs[i], test_rht_params);
+		if (err > 0) {
+			insert_retries += err;
+		} else if (err) {
+			pr_err("  thread[%d]: rhashtable_insert_fast failed\n",
+			       tdata->id);
+			goto out;
+		}
+	}
+	if (insert_retries)
+		pr_info("  thread[%d]: %u insertions retried due to memory pressure\n",
+			tdata->id, insert_retries);
+
+	err = thread_lookup_test(tdata);
+	if (err) {
+		pr_err("  thread[%d]: rhashtable_lookup_test failed\n",
+		       tdata->id);
+		goto out;
+	}
+
+	for (step = 10; step > 0; step--) {
+		for (i = 0; i < tdata->entries; i += step) {
+			if (tdata->objs[i].value.id == TEST_INSERT_FAIL)
+				continue;
+			err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
+			                             test_rht_params);
+			if (err) {
+				pr_err("  thread[%d]: rhashtable_remove_fast failed\n",
+				       tdata->id);
+				goto out;
+			}
+			tdata->objs[i].value.id = TEST_INSERT_FAIL;
+
+			cond_resched();
+		}
+		err = thread_lookup_test(tdata);
+		if (err) {
+			pr_err("  thread[%d]: rhashtable_lookup_test (2) failed\n",
+			       tdata->id);
+			goto out;
+		}
+	}
+out:
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
+	return err;
+}
+
+static int __init test_rht_init(void)
+{
+	unsigned int entries;
+	int i, err, started_threads = 0, failed_threads = 0;
+	u64 total_time = 0;
+	struct thread_data *tdata;
+	struct test_obj *objs;
+
+	if (parm_entries < 0)
+		parm_entries = 1;
+
+	entries = min(parm_entries, MAX_ENTRIES);
+
+	test_rht_params.automatic_shrinking = shrinking;
+	test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);
+	test_rht_params.nelem_hint = size;
+
+	objs = vzalloc(array_size(sizeof(struct test_obj),
+				  test_rht_params.max_size + 1));
+	if (!objs)
+		return -ENOMEM;
+
+	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
+		size, max_size, shrinking);
+
+	for (i = 0; i < runs; i++) {
+		s64 time;
+
+		pr_info("Test %02d:\n", i);
+		memset(objs, 0, test_rht_params.max_size * sizeof(struct test_obj));
+
+		err = rhashtable_init(&ht, &test_rht_params);
+		if (err < 0) {
+			pr_warn("Test failed: Unable to initialize hashtable: %d\n",
+				err);
+			continue;
+		}
+
+		time = test_rhashtable(&ht, objs, entries);
+		rhashtable_destroy(&ht);
+		if (time < 0) {
+			vfree(objs);
+			pr_warn("Test failed: return code %lld\n", time);
+			return -EINVAL;
+		}
+
+		total_time += time;
+	}
+
+	pr_info("test if its possible to exceed max_size %d: %s\n",
+			test_rht_params.max_size, test_rhashtable_max(objs, entries) == 0 ?
+			"no, ok" : "YES, failed");
+	vfree(objs);
+
+	do_div(total_time, runs);
+	pr_info("Average test time: %llu\n", total_time);
+
+	test_insert_duplicates_run();
+
+	if (!tcount)
+		return 0;
+
+	pr_info("Testing concurrent rhashtable access from %d threads\n",
+	        tcount);
+	atomic_set(&startup_count, tcount);
+	tdata = vzalloc(array_size(tcount, sizeof(struct thread_data)));
+	if (!tdata)
+		return -ENOMEM;
+	objs  = vzalloc(array3_size(sizeof(struct test_obj), tcount, entries));
+	if (!objs) {
+		vfree(tdata);
+		return -ENOMEM;
+	}
+
+	test_rht_params.max_size = max_size ? :
+	                           roundup_pow_of_two(tcount * entries);
+	err = rhashtable_init(&ht, &test_rht_params);
+	if (err < 0) {
+		pr_warn("Test failed: Unable to initialize hashtable: %d\n",
+			err);
+		vfree(tdata);
+		vfree(objs);
+		return -EINVAL;
+	}
+	for (i = 0; i < tcount; i++) {
+		tdata[i].id = i;
+		tdata[i].entries = entries;
+		tdata[i].objs = objs + i * entries;
+		tdata[i].task = kthread_run(threadfunc, &tdata[i],
+		                            "rhashtable_thrad[%d]", i);
+		if (IS_ERR(tdata[i].task)) {
+			pr_err(" kthread_run failed for thread %d\n", i);
+			atomic_dec(&startup_count);
+		} else {
+			started_threads++;
+		}
+	}
+	if (wait_event_interruptible(startup_wait, atomic_read(&startup_count) == 0))
+		pr_err("  wait_event interruptible failed\n");
+	/* count is 0 now, set it to -1 and wake up all threads together */
+	atomic_dec(&startup_count);
+	wake_up_all(&startup_wait);
+	for (i = 0; i < tcount; i++) {
+		if (IS_ERR(tdata[i].task))
+			continue;
+		if ((err = kthread_stop(tdata[i].task))) {
+			pr_warn("Test failed: thread %d returned: %d\n",
+			        i, err);
+			failed_threads++;
+		}
+	}
+	rhashtable_destroy(&ht);
+	vfree(tdata);
+	vfree(objs);
+
+	/*
+	 * rhltable_remove is very expensive, default values can cause test
+	 * to run for 2 minutes or more,  use a smaller number instead.
+	 */
+	err = test_rhltable(entries / 16);
+	pr_info("Started %d threads, %d failed, rhltable test returns %d\n",
+	        started_threads, failed_threads, err);
+	return 0;
+}
+
+static void __exit test_rht_exit(void)
+{
+}
+
+module_init(test_rht_init);
+module_exit(test_rht_exit);
+
+MODULE_LICENSE("GPL v2");