[PATCH v4 2/4] maple_tree: add test for expanding range in RCU mode

[Peng Zhang <zhangpeng.00@bytedance.com>]

Add test for expanding range in RCU mode. If we use the fast path of the
slot store to expand range in RCU mode, this test will fail.

Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 tools/testing/radix-tree/maple.c | 75 ++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index 03539d86cdf0..312c0d9fcbae 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -45,6 +45,13 @@ struct rcu_test_struct2 {
 	unsigned long last[RCU_RANGE_COUNT];
 };
 
+struct rcu_test_struct3 {
+	struct maple_tree *mt;
+	unsigned long index;
+	unsigned long last;
+	bool stop;
+};
+
 struct rcu_reader_struct {
 	unsigned int id;
 	int mod;
@@ -34954,6 +34961,70 @@ void run_check_rcu(struct maple_tree *mt, struct rcu_test_struct *vals)
 	MT_BUG_ON(mt, !vals->seen_entry2);
 }
 
+static void *rcu_slot_store_reader(void *ptr)
+{
+	struct rcu_test_struct3 *test = ptr;
+	MA_STATE(mas, test->mt, test->index, test->index);
+
+	rcu_register_thread();
+
+	rcu_read_lock();
+	while (!test->stop) {
+		mas_walk(&mas);
+		/* The length of growth to both sides must be equal. */
+		RCU_MT_BUG_ON(test, (test->index - mas.index) !=
+				    (mas.last - test->last));
+	}
+	rcu_read_unlock();
+
+	rcu_unregister_thread();
+	return NULL;
+}
+
+static noinline void run_check_rcu_slot_store(struct maple_tree *mt)
+{
+	pthread_t readers[20];
+	int range_cnt = 200, i, limit = 10000;
+	unsigned long len = ULONG_MAX / range_cnt, start, end;
+	struct rcu_test_struct3 test = {.stop = false, .mt = mt};
+
+	start = range_cnt / 2 * len;
+	end = start + len - 1;
+	test.index = start;
+	test.last = end;
+
+	for (i = 0; i < range_cnt; i++) {
+		mtree_store_range(mt, i * len, i * len + len - 1,
+				  xa_mk_value(i * 100), GFP_KERNEL);
+	}
+
+	mt_set_in_rcu(mt);
+	MT_BUG_ON(mt, !mt_in_rcu(mt));
+
+	for (i = 0; i < ARRAY_SIZE(readers); i++) {
+		if (pthread_create(&readers[i], NULL, rcu_slot_store_reader,
+				   &test)) {
+			perror("creating reader thread");
+			exit(1);
+		}
+	}
+
+	usleep(5);
+
+	while (limit--) {
+		/* Step by step, expand the most middle range to both sides. */
+		mtree_store_range(mt, --start, ++end, xa_mk_value(100),
+				  GFP_KERNEL);
+	}
+
+	test.stop = true;
+
+	while (i--)
+		pthread_join(readers[i], NULL);
+
+	mt_validate(mt);
+}
+
 static noinline
 void run_check_rcu_slowread(struct maple_tree *mt, struct rcu_test_struct *vals)
 {
@@ -35206,6 +35277,10 @@ static noinline void __init check_rcu_threaded(struct maple_tree *mt)
 	run_check_rcu(mt, &vals);
 	mtree_destroy(mt);
 
+	/* Check expanding range in RCU mode */
+	mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+	run_check_rcu_slot_store(mt);
+	mtree_destroy(mt);
 
 	/* Forward writer for rcu stress */
 	mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
-- 
2.20.1