rtla: Start the tracers after creating all instances

Group all start tracing after finishing creating all instances.

The tracing instance starts first for the case of hitting a stop
tracing while enabling other instances. The trace instance is the
one with most valuable information.

Link: https://lkml.kernel.org/r/67da7a703a56f75d7cd46568525145a65501a7e8.1686066600.git.bristot@kernel.org

Cc: William White <chwhite@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: Daniel Bristot de Oliveira

tools/tracing/rtla/src/osnoise_hist.c

@@ -870,8 +870,6 @@ int osnoise_hist_main(int argc, char *argv[])
 		}
 	}
 
-	trace_instance_start(trace);
-
 	if (params->trace_output) {
 		record = osnoise_init_trace_tool("osnoise");
 		if (!record) {
@@ -885,9 +883,19 @@ int osnoise_hist_main(int argc, char *argv[])
 				goto out_hist;
 		}
 
-		trace_instance_start(&record->trace);
 	}
 
+	/*
+	 * Start the tracer here, after having set all instances.
+	 *
+	 * Let the trace instance start first for the case of hitting a stop
+	 * tracing while enabling other instances. The trace instance is the
+	 * one with most valuable information.
+	 */
+	if (params->trace_output)
+		trace_instance_start(&record->trace);
+	trace_instance_start(trace);
+
 	tool->start_time = time(NULL);
 	osnoise_hist_set_signals(params);
 

tools/tracing/rtla/src/osnoise_top.c

@@ -697,8 +697,6 @@ int osnoise_top_main(int argc, char **argv)
 		}
 	}
 
-	trace_instance_start(trace);
-
 	if (params->trace_output) {
 		record = osnoise_init_trace_tool("osnoise");
 		if (!record) {
@@ -711,9 +709,18 @@ int osnoise_top_main(int argc, char **argv)
 			if (retval)
 				goto out_top;
 		}
+	}
 
+	/*
+	 * Start the tracer here, after having set all instances.
+	 *
+	 * Let the trace instance start first for the case of hitting a stop
+	 * tracing while enabling other instances. The trace instance is the
+	 * one with most valuable information.
+	 */
+	if (params->trace_output)
 		trace_instance_start(&record->trace);
-	}
+	trace_instance_start(trace);
 
 	tool->start_time = time(NULL);
 	osnoise_top_set_signals(params);

tools/tracing/rtla/src/timerlat_hist.c

@@ -922,8 +922,6 @@ int timerlat_hist_main(int argc, char *argv[])
 		}
 	}
 
-	trace_instance_start(trace);
-
 	if (params->trace_output) {
 		record = osnoise_init_trace_tool("timerlat");
 		if (!record) {
@@ -936,8 +934,6 @@ int timerlat_hist_main(int argc, char *argv[])
 			if (retval)
 				goto out_hist;
 		}
-
-		trace_instance_start(&record->trace);
 	}
 
 	if (!params->no_aa) {
@@ -956,9 +952,20 @@ int timerlat_hist_main(int argc, char *argv[])
 			err_msg("Failed to enable timerlat tracer\n");
 			goto out_hist;
 		}
+	}
 
+	/*
+	 * Start the tracers here, after having set all instances.
+	 *
+	 * Let the trace instance start first for the case of hitting a stop
+	 * tracing while enabling other instances. The trace instance is the
+	 * one with most valuable information.
+	 */
+	if (params->trace_output)
+		trace_instance_start(&record->trace);
+	if (!params->no_aa)
 		trace_instance_start(&aa->trace);
-	}
+	trace_instance_start(trace);
 
 	tool->start_time = time(NULL);
 	timerlat_hist_set_signals(params);

tools/tracing/rtla/src/timerlat_top.c

@@ -743,8 +743,6 @@ int timerlat_top_main(int argc, char *argv[])
 		}
 	}
 
-	trace_instance_start(trace);
-
 	if (params->trace_output) {
 		record = osnoise_init_trace_tool("timerlat");
 		if (!record) {
@@ -757,8 +755,6 @@ int timerlat_top_main(int argc, char *argv[])
 			if (retval)
 				goto out_top;
 		}
-
-		trace_instance_start(&record->trace);
 	}
 
 	if (!params->no_aa) {
@@ -785,11 +781,22 @@ int timerlat_top_main(int argc, char *argv[])
 				err_msg("Failed to enable timerlat tracer\n");
 				goto out_top;
 			}
-
-			trace_instance_start(&aa->trace);
 		}
 	}
 
+	/*
+	 * Start the tracers here, after having set all instances.
+	 *
+	 * Let the trace instance start first for the case of hitting a stop
+	 * tracing while enabling other instances. The trace instance is the
+	 * one with most valuable information.
+	 */
+	if (params->trace_output)
+		trace_instance_start(&record->trace);
+	if (!params->no_aa && aa != top)
+		trace_instance_start(&aa->trace);
+	trace_instance_start(trace);
+
 	top->start_time = time(NULL);
 	timerlat_top_set_signals(params);