tracing: Report wrong dynamic event command

Report wrong dynamic event type in the command via error_log.
-----
 # echo "z hoge" > /sys/kernel/tracing/dynamic_events
 sh: write error: Invalid argument
 # cat /sys/kernel/tracing/error_log
 [   22.977022] dynevent: error: No matching dynamic event type
   Command: z hoge
            ^
-----

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/176278970056.343441.10528135217342926645.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index d06854bd32b357cca5f492b5811af741caa66fb4..c4dfbc293baeeabb866d7639af39a5f30d4435ac 100644 (file)
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -144,9 +144,16 @@ static int create_dyn_event(const char *raw_command)
                if (!ret || ret != -ECANCELED)
                        break;
        }
-       mutex_unlock(&dyn_event_ops_mutex);
-       if (ret == -ECANCELED)
+       if (ret == -ECANCELED) {
+               static const char *err_msg[] = {"No matching dynamic event type"};
+
+               /* Wrong dynamic event. Leave an error message. */
+               tracing_log_err(NULL, "dynevent", raw_command, err_msg,
+                               0, 0);
                ret = -EINVAL;
+       }
+
+       mutex_unlock(&dyn_event_ops_mutex);
 
        return ret;
 }