5 files changed, 247 insertions, 0 deletions

diff --git a/Documentation/fault-injection/notifier-error-inject.txt b/Documentation/fault-injection/notifier-error-inject.txt
new file mode 100644
index 000000000000..c83526c364e5
--- /dev/null
+++ b/Documentation/fault-injection/notifier-error-inject.txt
@@ -0,0 +1,99 @@
+Notifier error injection
+========================
+
+Notifier error injection provides the ability to inject artifical errors to
+specified notifier chain callbacks. It is useful to test the error handling of
+notifier call chain failures which is rarely executed.  There are kernel
+modules that can be used to test the following notifiers.
+
+ * CPU notifier
+ * PM notifier
+ * Memory hotplug notifier
+ * powerpc pSeries reconfig notifier
+
+CPU notifier error injection module
+-----------------------------------
+This feature can be used to test the error handling of the CPU notifiers by
+injecting artifical errors to CPU notifier chain callbacks.
+
+If the notifier call chain should be failed with some events notified, write
+the error code to debugfs interface
+/sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error
+
+Possible CPU notifier events to be failed are:
+
+ * CPU_UP_PREPARE
+ * CPU_UP_PREPARE_FROZEN
+ * CPU_DOWN_PREPARE
+ * CPU_DOWN_PREPARE_FROZEN
+
+Example1: 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
+
+Example2: inject CPU online error (-2 == -ENOENT)
+
+        # echo -2 > actions/CPU_UP_PREPARE/error
+        # echo 1 > /sys/devices/system/cpu/cpu1/online
+        bash: echo: write error: No such file or directory
+
+PM notifier error injection module
+----------------------------------
+This feature is controlled through debugfs interface
+/sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error
+
+Possible PM notifier events to be failed are:
+
+ * PM_HIBERNATION_PREPARE
+ * PM_SUSPEND_PREPARE
+ * PM_RESTORE_PREPARE
+
+Example: Inject PM suspend error (-12 = -ENOMEM)
+
+        # cd /sys/kernel/debug/notifier-error-inject/pm/
+        # echo -12 > actions/PM_SUSPEND_PREPARE/error
+        # echo mem > /sys/power/state
+        bash: echo: write error: Cannot allocate memory
+
+Memory hotplug notifier error injection module
+----------------------------------------------
+This feature is controlled through debugfs interface
+/sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error
+
+Possible memory notifier events to be failed are:
+
+ * MEM_GOING_ONLINE
+ * MEM_GOING_OFFLINE
+
+Example: Inject memory hotplug offline error (-12 == -ENOMEM)
+
+        # cd /sys/kernel/debug/notifier-error-inject/memory
+        # echo -12 > actions/MEM_GOING_OFFLINE/error
+        # echo offline > /sys/devices/system/memory/memoryXXX/state
+        bash: echo: write error: Cannot allocate memory
+
+powerpc pSeries reconfig notifier error injection module
+--------------------------------------------------------
+This feature is controlled through debugfs interface
+/sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error
+
+Possible pSeries reconfig notifier events to be failed are:
+
+ * PSERIES_RECONFIG_ADD
+ * PSERIES_RECONFIG_REMOVE
+ * PSERIES_DRCONF_MEM_ADD
+ * PSERIES_DRCONF_MEM_REMOVE
+
+For more usage examples
+-----------------------
+There are tools/testing/selftests using the notifier error injection features
+for CPU and memory notifiers.
+
+ * tools/testing/selftests/cpu-hotplug/on-off-test.sh
+ * tools/testing/selftests/memory-hotplug/on-off-test.sh
+
+These scripts first do simple online and offline tests and then do fault
+injection tests if notifier error injection module is available.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 4a186508bf8b..bdee91d50a5b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1084,6 +1084,17 @@ config LKDTM
         Documentation on how to use the module can be found in
         Documentation/fault-injection/provoke-crashes.txt
 
+config NOTIFIER_ERROR_INJECTION
+        tristate "Notifier error injection"
+        depends on DEBUG_KERNEL
+        select DEBUG_FS
+        help
+          This option provides the ability to inject artifical errors to
+          specified notifier chain callbacks. It is useful to test the error
+          handling of notifier call chain failures.
+
+          Say N if unsure.
+
 config CPU_NOTIFIER_ERROR_INJECT
         tristate "CPU notifier error injection module"
         depends on HOTPLUG_CPU && DEBUG_KERNEL
diff --git a/lib/Makefile b/lib/Makefile
index df663cc05c73..71acfa4489f3 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
 obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
 obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
+obj-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o
 obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
 
 lib-$(CONFIG_GENERIC_BUG) += bug.o
diff --git a/lib/notifier-error-inject.c b/lib/notifier-error-inject.c
new file mode 100644
index 000000000000..44b92cb6224f
--- /dev/null
+++ b/lib/notifier-error-inject.c
@@ -0,0 +1,112 @@
+#include <linux/module.h>
+
+#include "notifier-error-inject.h"
+
+static int debugfs_errno_set(void *data, u64 val)
+{
+        *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
+        return 0;
+}
+
+static int debugfs_errno_get(void *data, u64 *val)
+{
+        *val = *(int *)data;
+        return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
+                        "%lld\n");
+
+static struct dentry *debugfs_create_errno(const char *name, mode_t mode,
+                                struct dentry *parent, int *value)
+{
+        return debugfs_create_file(name, mode, parent, value, &fops_errno);
+}
+
+static int notifier_err_inject_callback(struct notifier_block *nb,
+                                unsigned long val, void *p)
+{
+        int err = 0;
+        struct notifier_err_inject *err_inject =
+                container_of(nb, struct notifier_err_inject, nb);
+        struct notifier_err_inject_action *action;
+
+        for (action = err_inject->actions; action->name; action++) {
+                if (action->val == val) {
+                        err = action->error;
+                        break;
+                }
+        }
+        if (err)
+                pr_info("Injecting error (%d) to %s\n", err, action->name);
+
+        return notifier_from_errno(err);
+}
+
+struct dentry *notifier_err_inject_dir;
+EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
+
+struct dentry *notifier_err_inject_init(const char *name, struct dentry *parent,
+                        struct notifier_err_inject *err_inject, int priority)
+{
+        struct notifier_err_inject_action *action;
+        mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+        struct dentry *dir;
+        struct dentry *actions_dir;
+
+        err_inject->nb.notifier_call = notifier_err_inject_callback;
+        err_inject->nb.priority = priority;
+
+        dir = debugfs_create_dir(name, parent);
+        if (!dir)
+                return ERR_PTR(-ENOMEM);
+
+        actions_dir = debugfs_create_dir("actions", dir);
+        if (!actions_dir)
+                goto fail;
+
+        for (action = err_inject->actions; action->name; action++) {
+                struct dentry *action_dir;
+
+                action_dir = debugfs_create_dir(action->name, actions_dir);
+                if (!action_dir)
+                        goto fail;
+
+                /*
+                 * Create debugfs r/w file containing action->error. If
+                 * notifier call chain is called with action->val, it will
+                 * fail with the error code
+                 */
+                if (!debugfs_create_errno("error", mode, action_dir,
+                                        &action->error))
+                        goto fail;
+        }
+        return dir;
+fail:
+        debugfs_remove_recursive(dir);
+        return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(notifier_err_inject_init);
+
+static int __init err_inject_init(void)
+{
+        notifier_err_inject_dir =
+                debugfs_create_dir("notifier-error-inject", NULL);
+
+        if (!notifier_err_inject_dir)
+                return -ENOMEM;
+
+        return 0;
+}
+
+static void __exit err_inject_exit(void)
+{
+        debugfs_remove_recursive(notifier_err_inject_dir);
+}
+
+module_init(err_inject_init);
+module_exit(err_inject_exit);
+
+MODULE_DESCRIPTION("Notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
diff --git a/lib/notifier-error-inject.h b/lib/notifier-error-inject.h
new file mode 100644
index 000000000000..99b3b6fc470b
--- /dev/null
+++ b/lib/notifier-error-inject.h
@@ -0,0 +1,24 @@
+#include <linux/atomic.h>
+#include <linux/debugfs.h>
+#include <linux/notifier.h>
+
+struct notifier_err_inject_action {
+        unsigned long val;
+        int error;
+        const char *name;
+};
+
+#define NOTIFIER_ERR_INJECT_ACTION(action)      \
+        .name = #action, .val = (action),
+
+struct notifier_err_inject {
+        struct notifier_block nb;
+        struct notifier_err_inject_action actions[];
+        /* The last slot must be terminated with zero sentinel */
+};
+
+extern struct dentry *notifier_err_inject_dir;
+
+extern struct dentry *notifier_err_inject_init(const char *name,
+                struct dentry *parent, struct notifier_err_inject *err_inject,
+                int priority);