Merge branch 'rhltable-dups'

Paul Blakey says:

====================
rhashtable: Fix rhltable duplicates insertion

On our mlx5 driver fs_core.c, we use the rhltable interface to store
flow groups. We noticed that sometimes we get a warning that flow group isn't
found at removal. This rare case was caused when a specific scenario happened,
insertion of a flow group with a similar match criteria (a duplicate),
but only where the flow group rhash_head was second (or not first)
on the relevant rhashtable bucket list.

The first patch fixes it, and the second one adds a test that show
it is now working.

Paul.

v3 --> v2 changes:
    * added missing fix in rhashtable_lookup_one code path as well.

v1 --> v2 changes:
    * Changed commit messages to better reflect the change
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2018-03-07 10:44:13 -05:00
commit 6f22c07f03
3 changed files with 140 additions and 2 deletions

View File

@ -766,8 +766,10 @@ static inline void *__rhashtable_insert_fast(
if (!key ||
(params.obj_cmpfn ?
params.obj_cmpfn(&arg, rht_obj(ht, head)) :
rhashtable_compare(&arg, rht_obj(ht, head))))
rhashtable_compare(&arg, rht_obj(ht, head)))) {
pprev = &head->next;
continue;
}
data = rht_obj(ht, head);

View File

@ -506,8 +506,10 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
if (!key ||
(ht->p.obj_cmpfn ?
ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) :
rhashtable_compare(&arg, rht_obj(ht, head))))
rhashtable_compare(&arg, rht_obj(ht, head)))) {
pprev = &head->next;
continue;
}
if (!ht->rhlist)
return rht_obj(ht, head);

View File

@ -79,6 +79,21 @@ struct thread_data {
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) << RHT_HASH_RESERVED_SPACE;
}
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),
@ -87,6 +102,17 @@ static struct rhashtable_params test_rht_params = {
.nulls_base = (3U << RHT_BASE_SHIFT),
};
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);
@ -465,6 +491,112 @@ static int __init test_rhashtable_max(struct test_obj *array,
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;
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\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);
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;
err = rhltable_init(&rhlt, &test_rht_params_dup);
if (WARN_ON(err))
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);
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;
@ -613,6 +745,8 @@ static int __init test_rht_init(void)
do_div(total_time, runs);
pr_info("Average test time: %llu\n", total_time);
test_insert_duplicates_run();
if (!tcount)
return 0;