tracing/user_events: Fix incorrect return value for writing operation when events are disabled

The writing operation return the count of writes regardless of whether events
are enabled or disabled. Switch it to return -EBADF to indicates that the event
is disabled.

Link: https://lkml.kernel.org/r/[email protected]

Cc: [email protected]
7f5a08c ("user_events: Add minimal support for trace_event into ftrace")
Acked-by: Beau Belgrave <[email protected]>
Signed-off-by: sunliming <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: sunliming

kernel/trace/trace_events_user.c

@@ -2096,7 +2096,8 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
 
 		if (unlikely(faulted))
 			return -EFAULT;
-	}
+	} else
+		return -EBADF;
 
 	return ret;
 }