[PATCH 6.0 456/862] selftests/cpu-hotplug: Reserve one cpu online at least

[Greg Kroah-Hartman]

From: Zhao Gongyi <zhaogongyi@xxxxxxxxxx>

[ Upstream commit 51d4c851465c32143d9c7b1cfb46fc581922b116 ]

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@xxxxxxxxxx>
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 .../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 32ec7e4489ee..4c1d6d9abecc 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
-- 
2.35.1