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linux/lib/test_rhashtable.c
Tom Herbert 97a6ec4ac0 rhashtable: Change rhashtable_walk_start to return void 
Most callers of rhashtable_walk_start don't care about a resize event
which is indicated by a return value of -EAGAIN. So calls to
rhashtable_walk_start are wrapped wih code to ignore -EAGAIN. Something
like this is common:

       ret = rhashtable_walk_start(rhiter);
       if (ret && ret != -EAGAIN)
               goto out;

Since zero and -EAGAIN are the only possible return values from the
function this check is pointless. The condition never evaluates to true.

This patch changes rhashtable_walk_start to return void. This simplifies
code for the callers that ignore -EAGAIN. For the few cases where the
caller cares about the resize event, particularly where the table can be
walked in mulitple parts for netlink or seq file dump, the function
rhashtable_walk_start_check has been added that returns -EAGAIN on a
resize event.

Signed-off-by: Tom Herbert <tom@quantonium.net>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-11 09:58:38 -05:00

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/*
* 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 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,
.nulls_base = (3U << RHT_BASE_SHIFT),
};
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\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 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\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(sizeof(*rhl_test_objects) * entries);
if (!rhl_test_objects)
return -ENOMEM;
ret = -ENOMEM;
obj_in_table = vzalloc(BITS_TO_LONGS(entries) * sizeof(unsigned long));
if (!obj_in_table)
goto out_free;
/* nulls_base not supported in rhlist interface */
test_rht_params.nulls_base = 0;
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-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\n",
ht.max_elems, -E2BIG, err);
if (err == 0)
err = -1;
}
rhashtable_destroy(&ht);
return err;
}
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;
up(&prestart_sem);
if (down_interruptible(&startup_sem))
pr_err(" thread[%d]: down_interruptible failed\n", 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\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((test_rht_params.max_size + 1) * sizeof(struct test_obj));
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);
if (!tcount)
return 0;
pr_info("Testing concurrent rhashtable access from %d threads\n",
tcount);
sema_init(&prestart_sem, 1 - tcount);
tdata = vzalloc(tcount * sizeof(struct thread_data));
if (!tdata)
return -ENOMEM;
objs = vzalloc(tcount * entries * sizeof(struct test_obj));
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);
else
started_threads++;
}
if (down_interruptible(&prestart_sem))
pr_err(" down interruptible failed\n");
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\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");
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