docs: cgroup-v2: fix misc.events key format descriptiongrafted

In misc cgroup, misc.events does not output a simple "max" key. Instead,
each registered misc resource outputs a separate key suffixed with ".max"
(i.e., "<res>.max").
Update the documentation to clarify that the entry key is "<res>.max".

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Cheng Lingfei <chenglingfei@foxmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/lib/netdev-notifier-error-inject.c b/lib/netdev-notifier-error-inject.c
new file mode 100644
index 000000000..bb930f279
--- /dev/null
+++ b/lib/netdev-notifier-error-inject.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+
+#include "notifier-error-inject.h"
+
+static int priority;
+module_param(priority, int, 0);
+MODULE_PARM_DESC(priority, "specify netdevice notifier priority");
+
+static struct notifier_err_inject netdev_notifier_err_inject = {
+	.actions = {
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_REGISTER) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_CHANGEMTU) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_CHANGENAME) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRE_UP) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRE_TYPE_CHANGE) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_POST_INIT) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRECHANGEMTU) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRECHANGEUPPER) },
+		{ NOTIFIER_ERR_INJECT_ACTION(NETDEV_CHANGEUPPER) },
+		{}
+	}
+};
+
+static struct dentry *dir;
+
+static int netdev_err_inject_init(void)
+{
+	int err;
+
+	dir = notifier_err_inject_init("netdev", notifier_err_inject_dir,
+				       &netdev_notifier_err_inject, priority);
+	if (IS_ERR(dir))
+		return PTR_ERR(dir);
+
+	err = register_netdevice_notifier(&netdev_notifier_err_inject.nb);
+	if (err)
+		debugfs_remove_recursive(dir);
+
+	return err;
+}
+
+static void netdev_err_inject_exit(void)
+{
+	unregister_netdevice_notifier(&netdev_notifier_err_inject.nb);
+	debugfs_remove_recursive(dir);
+}
+
+module_init(netdev_err_inject_init);
+module_exit(netdev_err_inject_exit);
+
+MODULE_DESCRIPTION("Netdevice notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nikolay Aleksandrov <razor@blackwall.org>");