From: Yu Kuai <yukuai3@huawei.com>

While testing throtl manually, it's found there is a deadlock problem,
add this regression test.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 tests/throtl/004 | 20 ++++++++++++++++++++
 tests/throtl/rc  | 11 +++++++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/tests/throtl/004 b/tests/throtl/004
index d1461b9..05a1c9d 100755
--- a/tests/throtl/004
+++ b/tests/throtl/004
@@ -7,6 +7,7 @@
 # commit 8f9e7b65f833 ("block: cancel all throttled bios in del_gendisk()")
 
 . tests/throtl/rc
+. common/scsi_debug
 
 DESCRIPTION="delete disk while IO is throttled"
 QUICK=1
@@ -14,7 +15,12 @@ QUICK=1
 test() {
 	echo "Running ${TEST_NAME}"
 
+	if ! _configure_scsi_debug; then
+		return 1;
+	fi
+
 	if ! _set_up_throtl; then
+		_exit_scsi_debug
 		return 1;
 	fi
 
@@ -29,6 +35,20 @@ test() {
 	echo 0 > "/sys/kernel/config/nullb/$THROTL_DEV/power"
 	wait $!
 
+	echo "$(cat /sys/block/${SCSI_DEBUG_DEVICES[0]}/dev) wbps=$((1024 * 1024))" > \
+			"$CGROUP2_DIR/$THROTL_DIR/io.max"
+
+	{
+		echo "$BASHPID" > "$CGROUP2_DIR/$THROTL_DIR/cgroup.procs"
+		_throtl_issue_io write 10M 1 ${SCSI_DEBUG_DEVICES[0]} &> /dev/null
+	} &
+
+	sleep 0.6
+	echo 1 > "/sys/block/${SCSI_DEBUG_DEVICES[0]}/device/delete"
+	wait $!
+
 	_clean_up_throtl
+	_exit_scsi_debug
+
 	echo "Test complete"
 }
diff --git a/tests/throtl/rc b/tests/throtl/rc
index 327084b..5f9f1d7 100644
--- a/tests/throtl/rc
+++ b/tests/throtl/rc
@@ -98,13 +98,20 @@ _throtl_issue_io() {
 	local start_time
 	local end_time
 	local elapsed
+	local testdev
+
+	if [ $# -ge 4 ]; then
+		testdev=$4
+	else
+		testdev=$THROTL_DEV
+	fi
 
 	start_time=$(date +%s.%N)
 
 	if [ "$1" == "read" ]; then
-		dd if=/dev/$THROTL_DEV of=/dev/null bs="$2" count="$3" iflag=direct status=none
+		dd if=/dev/$testdev of=/dev/null bs="$2" count="$3" iflag=direct status=none
 	elif [ "$1" == "write" ]; then
-		dd of=/dev/$THROTL_DEV if=/dev/zero bs="$2" count="$3" oflag=direct status=none
+		dd of=/dev/$testdev if=/dev/zero bs="$2" count="$3" oflag=direct status=none
 	fi
 
 	end_time=$(date +%s.%N)
-- 
2.39.2