[PATCH] rtla: reject -e, --filter and --trigger without --trace

[Chaosheng Qu]

From: Chaosheng Qu <quchaosheng000406@xxxxxxx>
Subject: [PATCH] rtla: reject -e, --filter and --trigger without --trace
To: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Tomas Glozar <tglozar@xxxxxxxxxx>,
    linux-trace-kernel@xxxxxxxxxxxxxxx,
    linux-kernel@xxxxxxxxxxxxxxx

-e, --filter and --trigger configure events of the trace instance that
--trace creates, and trace_events_enable() is only called from inside the
block that --trace or --on-end trace enters.  Without either of them the
options are parsed, stored in params->events and then never looked at
again: rtla runs to completion and exits 0, so the user is left believing
the events were enabled.

  # rtla osnoise top -e sched:sched_switch -d 1s
  ... runs for a second, exit 0, no trace file, event never enabled

  # rtla osnoise top -e nosuchsys:nosuchevent -d 1s
  ... exit 0, the typo goes unnoticed

Reject the combination instead.  This does not change what happens when
--trace is given: an invalid event still fails with "Error enabling
event", and a valid one still works.

Signed-off-by: Chaosheng Qu <quchaosheng000406@xxxxxxx>
---
diff --git a/tools/tracing/rtla/src/common.c b/tools/tracing/rtla/src/common.c
--- a/tools/tracing/rtla/src/common.c
+++ b/tools/tracing/rtla/src/common.c
@@ -203,6 +203,19 @@
 	}
 
 
+	/*
+	 * -e, --filter and --trigger configure events of the trace instance
+	 * that --trace creates.  Without it there is no instance to put them
+	 * in, and they used to be dropped without a word.
+	 */
+	if (params->events &&
+	    !params->threshold_actions.present[ACTION_TRACE_OUTPUT] &&
+	    !params->end_actions.present[ACTION_TRACE_OUTPUT]) {
+		err_msg("-e, --filter and --trigger need --trace or --on-end trace\n");
+		retval = 1;
+		goto out_free;
+	}
+
 	if (params->threshold_actions.present[ACTION_TRACE_OUTPUT] ||
 	    params->end_actions.present[ACTION_TRACE_OUTPUT]) {
 		tool->record = osnoise_init_trace_tool(ops->tracer);