tracing/eprobe: Fix alloc event dir failed when event name no set

The event dir will alloc failed when event name no set, using the
command:
"echo "e:esys/ syscalls/sys_enter_openat file=\$filename:string"
>> dynamic_events"
It seems that dir name="syscalls/sys_enter_openat" is not allowed
in debugfs. So just use the "sys_enter_openat" as the event name.

Link: https://lkml.kernel.org/r/1664028814-45923-1-git-send-email-chentao.kernel@linux.alibaba.com

Cc: Ingo Molnar <[email protected]>
Cc: Tom Zanussi <[email protected]>
Cc: Linyu Yuan <[email protected]>
Cc: Tao Chen <[email protected]
Cc: [email protected]
Fixes: 95c104c ("tracing: Auto generate event name when creating a group of events")
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Tao Chen <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: Tao Chen

kernel/trace/trace_eprobe.c

@@ -1039,8 +1039,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	}
 
 	if (!event) {
-		strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
-		sanitize_event_name(buf1);
+		strscpy(buf1, sys_event, MAX_EVENT_NAME_LEN);
 		event = buf1;
 	}