MDEV-17541 KILL QUERY during lock wait in FOREIGN KEY check causes hang

row_ins_check_foreign_constraint(): Do not overwrite hard errors
with the soft error DB_LOCK_WAIT. This prevents an infinite
wait loop when DB_INTERRUPTED was returned. For DB_LOCK_WAIT,
row_insert_for_mysql() would keep invoking row_ins_step() and the
transaction would remain active until the server shutdown is initiated.

1 files changed, 19 insertions, 2 deletions

diff --git a/mysql-test/suite/innodb/r/foreign_key.result b/mysql-test/suite/innodb/r/foreign_key.result
index a151651b594..831417aff5c 100644
--- a/mysql-test/suite/innodb/r/foreign_key.result
+++ b/mysql-test/suite/innodb/r/foreign_key.result
@@ -252,7 +252,6 @@ DELETE FROM t1 WHERE id = 1;
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 connection con1;
 COMMIT;
-disconnect con1;
 connection default;
 SELECT * FROM t2;
 id	ref_id	f
@@ -332,7 +331,25 @@ PRIMARY KEY  (store_id),
 UNIQUE KEY idx_unique_manager (manager_staff_id),
 CONSTRAINT fk_store_staff FOREIGN KEY (manager_staff_id) REFERENCES staff (staff_id) ON DELETE RESTRICT ON UPDATE CASCADE
 ) ENGINE=InnoDB;
-SET FOREIGN_KEY_CHECKS=DEFAULT;
 LOCK TABLE staff WRITE;
 UNLOCK TABLES;
 DROP TABLES staff, store;
+SET FOREIGN_KEY_CHECKS=1;
+#
+# MDEV-17541 KILL QUERY during lock wait in FOREIGN KEY check hangs
+#
+CREATE TABLE t1 (a INT PRIMARY KEY) ENGINE=InnoDB;
+CREATE TABLE t2 (a INT PRIMARY KEY, FOREIGN KEY (a) REFERENCES t1(a))
+ENGINE=InnoDB;
+connection con1;
+INSERT INTO t1 SET a=1;
+BEGIN;
+DELETE FROM t1;
+connection default;
+INSERT INTO t2 SET a=1;
+connection con1;
+kill query @id;
+connection default;
+ERROR 70100: Query execution was interrupted
+disconnect con1;
+DROP TABLE t2,t1;