rhashtable-test: Use walker to test bucket statistics

As resizes may continue to run in the background, use walker to
ensure we see all entries. Also print the encountered number
of rehashes queued up while traversing.

This may lead to warnings due to entries being seen multiple
times. We consider them non-fatal.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

lib/test_rhashtable.c

@@ -89,41 +89,43 @@ static int __init test_rht_lookup(struct rhashtable *ht)
 	return 0;
 }
 
-static void test_bucket_stats(struct rhashtable *ht, bool quiet)
+static void test_bucket_stats(struct rhashtable *ht)
 {
-	unsigned int cnt, rcu_cnt, i, total = 0;
+	unsigned int err, total = 0, chain_len = 0;
+	struct rhashtable_iter hti;
 	struct rhash_head *pos;
-	struct test_obj *obj;
-	struct bucket_table *tbl;
-
-	tbl = rht_dereference_rcu(ht->tbl, ht);
-	for (i = 0; i < tbl->size; i++) {
-		rcu_cnt = cnt = 0;
-
-		if (!quiet)
-			pr_info(" [%#4x/%u]", i, tbl->size);
 
-		rht_for_each_entry_rcu(obj, pos, tbl, i, node) {
-			cnt++;
-			total++;
-			if (!quiet)
-				pr_cont(" [%p],", obj);
+	err = rhashtable_walk_init(ht, &hti);
+	if (err) {
+		pr_warn("Test failed: allocation error");
+		return;
 	}
 
-		rht_for_each_entry_rcu(obj, pos, tbl, i, node)
-			rcu_cnt++;
+	err = rhashtable_walk_start(&hti);
+	if (err && err != -EAGAIN) {
+		pr_warn("Test failed: iterator failed: %d\n", err);
+		return;
+	}
 
-		if (rcu_cnt != cnt)
-			pr_warn("Test failed: Chain count mismach %d != %d",
-				cnt, rcu_cnt);
+	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;
+		}
 
-		if (!quiet)
-			pr_cont("\n  [%#x] first element: %p, chain length: %u\n",
-				i, tbl->buckets[i], cnt);
+		total++;
 	}
 
-	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d\n",
-		total, atomic_read(&ht->nelems), entries);
+	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 ^^^");
@@ -152,14 +154,12 @@ static s64 __init test_rhashtable(struct rhashtable *ht)
 			return err;
 	}
 
+	test_bucket_stats(ht);
 	rcu_read_lock();
-	test_bucket_stats(ht, true);
 	test_rht_lookup(ht);
 	rcu_read_unlock();
 
-	rcu_read_lock();
-	test_bucket_stats(ht, true);
-	rcu_read_unlock();
+	test_bucket_stats(ht);
 
 	pr_info("  Deleting %d keys\n", entries);
 	for (i = 0; i < entries; i++) {