rtla: Refactor save_trace_to_file

The functions osnoise_hist_main(), osnoise_top_main(),
timerlat_hist_main(), and timerlat_top_main() are lengthy and contain
duplicated code.

Refactor by consolidating the duplicate lines into the
save_trace_to_file() function.

Cc: Daniel Bristot de Oliveira <[e-mail]>
Cc: John Kacur <[e-mail]>
Cc: "Luis Claudio R. Goncalves" <[e-mail]>
Cc: Eder Zulian <[e-mail]>
Cc: Dan Carpenter <[e-mail]>
Cc: Gabriele Monaco <[e-mail]>
Link: https://lore.kernel.org/[e-mail]
Signed-off-by: Costa Shulyupin <[e-mail]>
Reviewed-by: Tomas Glozar <[e-mail]>
Tested-by: Tomas Glozar <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

tools/tracing/rtla/src/osnoise_hist.c

···
 
 	if (osnoise_trace_is_off(tool, record)) {
 		printf("rtla osnoise hit stop tracing\n");
-		if (params->trace_output) {
-			printf("  Saving trace to %s\n", params->trace_output);
-			save_trace_to_file(record->trace.inst, params->trace_output);
-		}
+		save_trace_to_file(record->trace.inst, params->trace_output);
 	}
 
 out_hist:

tools/tracing/rtla/src/osnoise_top.c

···
 
 	if (osnoise_trace_is_off(tool, record)) {
 		printf("osnoise hit stop tracing\n");
-		if (params->trace_output) {
-			printf("  Saving trace to %s\n", params->trace_output);
-			save_trace_to_file(record->trace.inst, params->trace_output);
-		}
+		save_trace_to_file(record->trace.inst, params->trace_output);
 	}
 
 out_top:

tools/tracing/rtla/src/timerlat_hist.c

···
 		if (!params->no_aa)
 			timerlat_auto_analysis(params->stop_us, params->stop_total_us);
 
-		if (params->trace_output) {
-			printf("  Saving trace to %s\n", params->trace_output);
-			save_trace_to_file(record->trace.inst, params->trace_output);
-		}
+		save_trace_to_file(record->trace.inst, params->trace_output);
 	}
 
 out_hist:

tools/tracing/rtla/src/timerlat_top.c

···
 		if (!params->no_aa)
 			timerlat_auto_analysis(params->stop_us, params->stop_total_us);
 
-		if (params->trace_output) {
-			printf("  Saving trace to %s\n", params->trace_output);
-			save_trace_to_file(record->trace.inst, params->trace_output);
-		}
+		save_trace_to_file(record->trace.inst, params->trace_output);
 	} else if (params->aa_only) {
 		/*
 		 * If the trace did not stop with --aa-only, at least print the

tools/tracing/rtla/src/trace.c

···
 	int out_fd, in_fd;
 	int retval = -1;
 
+	if (!filename)
+		return 0;
+
 	in_fd = tracefs_instance_file_open(inst, file, O_RDONLY);
 	if (in_fd < 0) {
 		err_msg("Failed to open trace file\n");
 		return -1;
 	}
 
+	printf("  Saving trace to %s\n", filename);
 	out_fd = creat(filename, mode);
 	if (out_fd < 0) {
 		err_msg("Failed to create output file %s\n", filename);