Considering that we can not offline all cpus in any cases,
we need to reserve one cpu online when the test offline all
hotpluggable online cpus, otherwise the test will fail forever.

Fixes: d89dffa976bc ("fault-injection: add selftests for cpu
and memory hotplug")

Signed-off-by: Zhao Gongyi <zhaogongyi@huawei.com>
---
 .../selftests/cpu-hotplug/cpu-on-off-test.sh  | 40 ++++++++++---------
 1 file changed, 22 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh b/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
index 184156763ccb..d5dc7e0dc726 100755
--- a/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
+++ b/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
@@ -149,6 +149,25 @@ offline_cpu_expect_fail()
 	fi
 }

+online_all_hot_pluggable_cpus()
+{
+	for cpu in `hotplaggable_offline_cpus`; do
+		online_cpu_expect_success $cpu
+	done
+}
+
+offline_all_hot_pluggable_cpus()
+{
+	local reserve_cpu=$online_max
+	for cpu in `hotpluggable_online_cpus`; do
+		# Reserve one cpu oneline at least.
+		if [ $cpu -eq $reserve_cpu ];then
+			continue
+		fi
+		offline_cpu_expect_success $cpu
+	done
+}
+
 allcpus=0
 online_cpus=0
 online_max=0
@@ -197,25 +216,10 @@ else
 	echo -e "\t online all offline cpus"
 fi

-#
-# Online all hot-pluggable CPUs
-#
-for cpu in `hotplaggable_offline_cpus`; do
-	online_cpu_expect_success $cpu
-done
+online_all_hot_pluggable_cpus

-#
-# Offline all hot-pluggable CPUs
-#
-for cpu in `hotpluggable_online_cpus`; do
-	offline_cpu_expect_success $cpu
-done
+offline_all_hot_pluggable_cpus

-#
-# Online all hot-pluggable CPUs again
-#
-for cpu in `hotplaggable_offline_cpus`; do
-	online_cpu_expect_success $cpu
-done
+online_all_hot_pluggable_cpus

 exit $retval
--
2.17.1