/*
   * Resizable, Scalable, Concurrent Hash Table
   *

   * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>

   * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
   *

   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  /**************************************************************************
   * 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/semaphore.h>

  #include <linux/slab.h>

  #include <linux/sched.h>

  #include <linux/random.h>

  #include <linux/vmalloc.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 struct semaphore prestart_sem;
  static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);

  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
  ",
  			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
  ", key.id);

  			return -ENOENT;
  		} else if (!expected && obj) {
  			pr_warn("Test failed: Unexpected entry found for key %u
  ",

  				key.id);

  			return -EEXIST;
  		} else if (expected && obj) {

  			if (obj->value.id != i) {

  				pr_warn("Test failed: Lookup value mismatch %u!=%u
  ",

  					obj->value.id, i);

  				return -EINVAL;
  			}
  		}

  
  		cond_resched_rcu();

  	}
  
  	return 0;
  }

  static void test_bucket_stats(struct rhashtable *ht, unsigned int entries)

  {

  	unsigned int err, total = 0, chain_len = 0;
  	struct rhashtable_iter hti;

  	struct rhash_head *pos;

  	err = rhashtable_walk_init(ht, &hti, GFP_KERNEL);

  	if (err) {
  		pr_warn("Test failed: allocation error");
  		return;
  	}

  	rhashtable_walk_start(&hti);

  	while ((pos = rhashtable_walk_next(&hti))) {
  		if (PTR_ERR(pos) == -EAGAIN) {
  			pr_info("Info: encountered resize
  ");
  			chain_len++;
  			continue;
  		} else if (IS_ERR(pos)) {
  			pr_warn("Test failed: rhashtable_walk_next() error: %ld
  ",
  				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
  ",
  		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
  ", 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
  ",
  			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
  ", 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
  ", 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
  ", 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
  ", 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
  ", 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
  ", err, i))
  			break;
  		if (err == 0)
  			set_bit(i, obj_in_table);
  	}
  
  	pr_info("test %d random rhlist add/delete operations
  ", 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-existant 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-existant 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
  ",
  				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_dereference(tbl->buckets[i], ht);
  		next = !rht_is_a_nulls(pos) ? rht_dereference(pos->next, ht) : NULL;
  
  		if (!rht_is_a_nulls(pos)) {
  			sprintf(buff, "%s
  bucket[%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 "
  ---- ht: ----%s
  -------------
  ", 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)
  ", err, i, cnt, slow? "slow" : "fast"))
  			goto skip_print;
  	}

  	ret = print_ht(rhlt);

  	WARN(ret != cnt, "missing rhltable elements (%d != %d, %s)
  ", 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
  ");
  
  	/* 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
  ", key.tid, key.id);

  			err++;

  		} else if (!obj && (tdata->objs[i].value.id != TEST_INSERT_FAIL)) {
  			pr_err("  object %d-%d not found!
  ", 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)
  ",
  			       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;
  
  	up(&prestart_sem);
  	if (down_interruptible(&startup_sem))
  		pr_err("  thread[%d]: down_interruptible failed
  ", tdata->id);

  	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
  ",
  			       tdata->id);
  			goto out;
  		}
  	}

  	if (insert_retries)
  		pr_info("  thread[%d]: %u insertions retried due to memory pressure
  ",
  			tdata->id, insert_retries);

  
  	err = thread_lookup_test(tdata);
  	if (err) {
  		pr_err("  thread[%d]: rhashtable_lookup_test failed
  ",
  		       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
  ",
  				       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
  ",
  			       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
  ",
  		size, max_size, shrinking);

  	for (i = 0; i < runs; i++) {
  		s64 time;

  		pr_info("Test %02d:
  ", 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
  ",
  				err);
  			continue;
  		}

  		time = test_rhashtable(&ht, objs, entries);

  		rhashtable_destroy(&ht);
  		if (time < 0) {

  			vfree(objs);

  			pr_warn("Test failed: return code %lld
  ", time);
  			return -EINVAL;
  		}
  
  		total_time += time;
  	}

  	pr_info("test if its possible to exceed max_size %d: %s
  ",
  			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
  ", total_time);

  	test_insert_duplicates_run();

  	if (!tcount)
  		return 0;
  
  	pr_info("Testing concurrent rhashtable access from %d threads
  ",
  	        tcount);
  	sema_init(&prestart_sem, 1 - 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
  ",
  			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
  ", i);
  		else
  			started_threads++;
  	}
  	if (down_interruptible(&prestart_sem))
  		pr_err("  down interruptible failed
  ");
  	for (i = 0; i < tcount; i++)
  		up(&startup_sem);
  	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
  ",
  			        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
  ",
  	        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");