selftests/cpu-hotplug: Fix check for cpu hotplug not supported

If CONFIG_HOTPLUG_CPU is disabled, /sys/devices/system/cpu/cpu*
directories are still populated, so the test fails to correctly detect
that CPU hotplug is not supported.

Fix this by checking for the presence of 'online' files in those
directories instead. The 'online' node is created for the given CPU if
and only if this CPU supports hotplug. So if none of the CPUs have
'online' nodes, it means CPU hotplug is not supported.

Signed-off-by: Dmytro Maluka <dmaluka@chromium.org>
Link: https://lore.kernel.org/r/20260319153825.2813576-1-dmaluka@chromium.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

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 6232a46ca6e16294e1ec6433bac29cc70c751ddb..287cfd5809f64b659fc9b7849ee06968062ee4aa 100755 (executable)
--- a/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
+++ b/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
@@ -24,7 +24,7 @@ prerequisite()
                exit $ksft_skip
        fi
 
-       if ! ls $SYSFS/devices/system/cpu/cpu* > /dev/null 2>&1; then
+       if ! ls $SYSFS/devices/system/cpu/cpu*/online > /dev/null 2>&1; then
                echo $msg cpu hotplug is not supported >&2
                exit $ksft_skip
        fi