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Commit 6f22c07f authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parents 25b5cdfc 499ac3b6

include/linux/rhashtable.h

+3 −1
Original line number Diff line number Diff line
@@ -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);

lib/rhashtable.c

+3 −1
Original line number Diff line number Diff line
@@ -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);

lib/test_rhashtable.c

+134 −0
Original line number Diff line number Diff line
@@ -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;