rtla: Fix segmentation fault when failing to enable -t

rtla osnoise and timerlat are causing a segmentation fault when running
with the --trace option on a kernel that does not support multiple
instances. For example:

    [root@f34 rtla]# rtla osnoise top -t
    failed to enable the tracer osnoise
    Could not enable osnoiser tracer for tracing
    Failed to enable the trace instance
    Segmentation fault (core dumped)

This error happens because the exit code of the tools is trying
to destroy the trace instance that failed to be created.

Make osnoise_destroy_tool() aware of possible NULL osnoise_tool *,
and do not attempt to destroy it. This also simplifies the exit code.

Link: https://lkml.kernel.org/r/5660a2b6bf66c2655842360f2d7f6b48db5dba23.1644327249.git.bristot@kernel.orgSuggested-by: Steven Rostedt <rostedt@goodmis.org>
Fixes: 1eceb2fc ("rtla/osnoise: Add osnoise top mode")
Fixes: 829a6c0b ("rtla/osnoise: Add the hist mode")
Fixes: a828cd18 ("rtla: Add timerlat tool and timelart top mode")
Fixes: 1eeb6328 ("rtla/timerlat: Add timerlat hist mode")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/tracing/rtla/src/osnoise.c

@@ -750,6 +750,9 @@ void osnoise_put_context(struct osnoise_context *context)
  */
 void osnoise_destroy_tool(struct osnoise_tool *top)
 {
+	if (!top)
+		return;
+
 	trace_instance_destroy(&top->trace);
 
 	if (top->context)

tools/tracing/rtla/src/osnoise_hist.c

@@ -701,9 +701,9 @@ osnoise_hist_set_signals(struct osnoise_hist_params *params)
 int osnoise_hist_main(int argc, char *argv[])
 {
 	struct osnoise_hist_params *params;
+	struct osnoise_tool *record = NULL;
+	struct osnoise_tool *tool = NULL;
 	struct trace_instance *trace;
-	struct osnoise_tool *record;
-	struct osnoise_tool *tool;
 	int return_value = 1;
 	int retval;
 
@@ -792,9 +792,8 @@ int osnoise_hist_main(int argc, char *argv[])
 out_hist:
 	osnoise_free_histogram(tool->data);
 out_destroy:
-	osnoise_destroy_tool(tool);
-	if (params->trace_output)
 	osnoise_destroy_tool(record);
+	osnoise_destroy_tool(tool);
 	free(params);
 out_exit:
 	exit(return_value);

tools/tracing/rtla/src/osnoise_top.c

@@ -483,9 +483,9 @@ static void osnoise_top_set_signals(struct osnoise_top_params *params)
 int osnoise_top_main(int argc, char **argv)
 {
 	struct osnoise_top_params *params;
+	struct osnoise_tool *record = NULL;
+	struct osnoise_tool *tool = NULL;
 	struct trace_instance *trace;
-	struct osnoise_tool *record;
-	struct osnoise_tool *tool;
 	int return_value = 1;
 	int retval;
 
@@ -571,9 +571,8 @@ int osnoise_top_main(int argc, char **argv)
 
 out_top:
 	osnoise_free_top(tool->data);
-	osnoise_destroy_tool(tool);
-	if (params->trace_output)
 	osnoise_destroy_tool(record);
+	osnoise_destroy_tool(tool);
 out_exit:
 	exit(return_value);
 }

tools/tracing/rtla/src/timerlat_hist.c

@@ -729,9 +729,9 @@ timerlat_hist_set_signals(struct timerlat_hist_params *params)
 int timerlat_hist_main(int argc, char *argv[])
 {
 	struct timerlat_hist_params *params;
+	struct osnoise_tool *record = NULL;
+	struct osnoise_tool *tool = NULL;
 	struct trace_instance *trace;
-	struct osnoise_tool *record;
-	struct osnoise_tool *tool;
 	int return_value = 1;
 	int retval;
 
@@ -813,9 +813,8 @@ int timerlat_hist_main(int argc, char *argv[])
 
 out_hist:
 	timerlat_free_histogram(tool->data);
-	osnoise_destroy_tool(tool);
-	if (params->trace_output)
 	osnoise_destroy_tool(record);
+	osnoise_destroy_tool(tool);
 	free(params);
 out_exit:
 	exit(return_value);

tools/tracing/rtla/src/timerlat_top.c

@@ -521,9 +521,9 @@ timerlat_top_set_signals(struct timerlat_top_params *params)
 int timerlat_top_main(int argc, char *argv[])
 {
 	struct timerlat_top_params *params;
+	struct osnoise_tool *record = NULL;
+	struct osnoise_tool *top = NULL;
 	struct trace_instance *trace;
-	struct osnoise_tool *record;
-	struct osnoise_tool *top;
 	int return_value = 1;
 	int retval;
 
@@ -609,9 +609,8 @@ int timerlat_top_main(int argc, char *argv[])
 
 out_top:
 	timerlat_free_top(top->data);
-	osnoise_destroy_tool(top);
-	if (params->trace_output)
 	osnoise_destroy_tool(record);
+	osnoise_destroy_tool(top);
 	free(params);
 out_exit:
 	exit(return_value);