1 files changed, 14 insertions, 2 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index bdee91d50a5b..20341480bb54 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1097,10 +1097,22 @@ config NOTIFIER_ERROR_INJECTION
 
 config CPU_NOTIFIER_ERROR_INJECT
         tristate "CPU notifier error injection module"
-        depends on HOTPLUG_CPU && DEBUG_KERNEL
+        depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
         help
           This option provides a kernel module that can be used to test
-          the error handling of the cpu notifiers
+          the error handling of the cpu notifiers by injecting artifical
+          errors to CPU notifier chain callbacks.  It is controlled through
+          debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
+
+          If the notifier call chain should be failed with some events
+          notified, write the error code to "actions/<notifier event>/error".
+
+          Example: Inject CPU offline error (-1 == -EPERM)
+
+          # cd /sys/kernel/debug/notifier-error-inject/cpu
+          # echo -1 > actions/CPU_DOWN_PREPARE/error
+          # echo 0 > /sys/devices/system/cpu/cpu1/online
+          bash: echo: write error: Operation not permitted
 
           To compile this code as a module, choose M here: the module will
           be called cpu-notifier-error-inject.