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.

Author: dr-m

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;

mysql-test/suite/innodb/t/foreign_key.test

@@ -228,7 +228,6 @@ DELETE FROM t1 WHERE id = 1;
 
 --connection con1
 COMMIT;
---disconnect con1
 
 --connection default
 SELECT * FROM t2;
@@ -288,8 +287,6 @@ insert into t1 values(1, 1);
 insert into t2(f1) values(1);
 drop table t2, t1;
 
---source include/wait_until_count_sessions.inc
-
 #
 # MDEV-12669 Circular foreign keys cause a loop and OOM upon LOCK TABLE
 #
@@ -308,8 +305,42 @@ CREATE TABLE store (
   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;
+
+--echo #
+--echo # MDEV-17541 KILL QUERY during lock wait in FOREIGN KEY check hangs
+--echo #
+
+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;
+let $ID= `SELECT @id := CONNECTION_ID()`;
+send INSERT INTO t2 SET a=1;
+
+connection con1;
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = 'update' and info = 'INSERT INTO t2 SET a=1';
+--source include/wait_condition.inc
+let $ignore= `SELECT @id := $ID`;
+kill query @id;
+
+connection default;
+--error ER_QUERY_INTERRUPTED
+reap;
+disconnect con1;
+
+DROP TABLE t2,t1;
+
+--source include/wait_until_count_sessions.inc

storage/innobase/row/row0ins.cc

@@ -1871,9 +1871,12 @@ row_ins_check_foreign_constraint(
 
 		thr->lock_state = QUE_THR_LOCK_NOLOCK;
 
-		if (check_table->to_be_dropped
-		    || trx->error_state == DB_LOCK_WAIT_TIMEOUT) {
+		err = trx->error_state;
+		if (err != DB_SUCCESS) {
+		} else if (check_table->to_be_dropped) {
 			err = DB_LOCK_WAIT_TIMEOUT;
+		} else {
+			err = DB_LOCK_WAIT;
 		}
 
 		my_atomic_addlint(&check_table->n_foreign_key_checks_running,