From 3e7b2ec4fe8ef4b05b33db3e84d1b1fbccde250e Mon Sep 17 00:00:00 2001
From: Thomas Graf <tgraf@suug.ch>
Date: Mon, 24 Nov 2014 12:37:58 +0100
Subject: rhashtable: Check for count mismatch while iterating in selftest

Verify whether both the lock and RCU protected iterators see all
test entries before and after expanding and shrinking has been
performed. Also verify whether the number of entries in the hashtable
remains stable during expansion and shrinking.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index e5f5e69..c7e987a 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -653,15 +653,15 @@ static int __init test_rht_lookup(struct rhashtable *ht)
 	return 0;
 }
 
-static void test_bucket_stats(struct rhashtable *ht,
-				     struct bucket_table *tbl,
-				     bool quiet)
+static void test_bucket_stats(struct rhashtable *ht, bool quiet)
 {
-	unsigned int cnt, i, total = 0;
+	unsigned int cnt, rcu_cnt, i, total = 0;
 	struct test_obj *obj;
+	struct bucket_table *tbl;
 
+	tbl = rht_dereference_rcu(ht->tbl, ht);
 	for (i = 0; i < tbl->size; i++) {
-		cnt = 0;
+		rcu_cnt = cnt = 0;
 
 		if (!quiet)
 			pr_info(" [%#4x/%zu]", i, tbl->size);
@@ -673,6 +673,13 @@ static void test_bucket_stats(struct rhashtable *ht,
 				pr_cont(" [%p],", obj);
 		}
 
+		rht_for_each_entry_rcu(obj, tbl->buckets[i], node)
+			rcu_cnt++;
+
+		if (rcu_cnt != cnt)
+			pr_warn("Test failed: Chain count mismach %d != %d",
+				cnt, rcu_cnt);
+
 		if (!quiet)
 			pr_cont("\n  [%#x] first element: %p, chain length: %u\n",
 				i, tbl->buckets[i], cnt);
@@ -680,6 +687,9 @@ static void test_bucket_stats(struct rhashtable *ht,
 
 	pr_info("  Traversal complete: counted=%u, nelems=%zu, entries=%d\n",
 		total, ht->nelems, TEST_ENTRIES);
+
+	if (total != ht->nelems || total != TEST_ENTRIES)
+		pr_warn("Test failed: Total count mismatch ^^^");
 }
 
 static int __init test_rhashtable(struct rhashtable *ht)
@@ -710,8 +720,7 @@ static int __init test_rhashtable(struct rhashtable *ht)
 	}
 
 	rcu_read_lock();
-	tbl = rht_dereference_rcu(ht->tbl, ht);
-	test_bucket_stats(ht, tbl, true);
+	test_bucket_stats(ht, true);
 	test_rht_lookup(ht);
 	rcu_read_unlock();
 
@@ -735,6 +744,10 @@ static int __init test_rhashtable(struct rhashtable *ht)
 		rcu_read_unlock();
 	}
 
+	rcu_read_lock();
+	test_bucket_stats(ht, true);
+	rcu_read_unlock();
+
 	pr_info("  Deleting %d keys\n", TEST_ENTRIES);
 	for (i = 0; i < TEST_ENTRIES; i++) {
 		u32 key = i * 2;
-- 
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