tools/rtla: Add fatal() and replace error handling pattern

The code contains some technical debt in error handling,
which complicates the consolidation of duplicated code.

Introduce an fatal() function to replace the common pattern of
err_msg() followed by exit(EXIT_FAILURE), reducing the length of an
already long function.

Further patches using fatal() follow.

Signed-off-by: Costa Shulyupin <[e-mail]>
Reviewed-by: Tomas Glozar <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Tomas Glozar <[e-mail]>

tools/tracing/rtla/src/osnoise_hist.c

···
 			break;
 		case 'e':
 			tevent = trace_event_alloc(optarg);
-			if (!tevent) {
-				err_msg("Error alloc trace event");
-				exit(EXIT_FAILURE);
-			}
+			if (!tevent)
+				fatal("Error alloc trace event");
 
 			if (params->common.events)
 				tevent->next = params->common.events;
···
 		case 'H':
 			params->common.hk_cpus = 1;
 			retval = parse_cpu_set(optarg, &params->common.hk_cpu_set);
-			if (retval) {
-				err_msg("Error parsing house keeping CPUs\n");
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Error parsing house keeping CPUs");
 			break;
 		case 'p':
 			params->period = get_llong_from_str(optarg);
···
 		case '4': /* trigger */
 			if (params->common.events) {
 				retval = trace_event_add_trigger(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding trigger %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding trigger %s", optarg);
 			} else {
 				osnoise_hist_usage("--trigger requires a previous -e\n");
 			}
···
 		case '5': /* filter */
 			if (params->common.events) {
 				retval = trace_event_add_filter(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding filter %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding filter %s", optarg);
 			} else {
 				osnoise_hist_usage("--filter requires a previous -e\n");
 			}
···
 		case '8':
 			retval = actions_parse(&params->common.threshold_actions, optarg,
 					       "osnoise_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		case '9':
 			retval = actions_parse(&params->common.end_actions, optarg,
 					       "osnoise_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		default:
 			osnoise_hist_usage("Invalid option");
···
 	if (trace_output)
 		actions_add_trace_output(&params->common.threshold_actions, trace_output);
 
-	if (geteuid()) {
-		err_msg("rtla needs root permission\n");
-		exit(EXIT_FAILURE);
-	}
+	if (geteuid())
+		fatal("rtla needs root permission");
 
 	if (params->common.hist.no_index && !params->common.hist.with_zeros)
 		osnoise_hist_usage("no-index set and with-zeros not set - it does not make sense");

tools/tracing/rtla/src/osnoise_top.c

···
 			break;
 		case 'e':
 			tevent = trace_event_alloc(optarg);
-			if (!tevent) {
-				err_msg("Error alloc trace event");
-				exit(EXIT_FAILURE);
-			}
+			if (!tevent)
+				fatal("Error alloc trace event");
 
 			if (params->common.events)
 				tevent->next = params->common.events;
···
 		case 'H':
 			params->common.hk_cpus = 1;
 			retval = parse_cpu_set(optarg, &params->common.hk_cpu_set);
-			if (retval) {
-				err_msg("Error parsing house keeping CPUs\n");
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Error parsing house keeping CPUs");
 			break;
 		case 'p':
 			params->period = get_llong_from_str(optarg);
···
 		case '0': /* trigger */
 			if (params->common.events) {
 				retval = trace_event_add_trigger(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding trigger %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding trigger %s", optarg);
 			} else {
 				osnoise_top_usage(params, "--trigger requires a previous -e\n");
 			}
···
 		case '1': /* filter */
 			if (params->common.events) {
 				retval = trace_event_add_filter(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding filter %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding filter %s", optarg);
 			} else {
 				osnoise_top_usage(params, "--filter requires a previous -e\n");
 			}
···
 		case '4':
 			retval = actions_parse(&params->common.threshold_actions, optarg,
 					       "osnoise_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		case '5':
 			retval = actions_parse(&params->common.end_actions, optarg,
 					       "osnoise_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		default:
 			osnoise_top_usage(params, "Invalid option");
···
 	if (trace_output)
 		actions_add_trace_output(&params->common.threshold_actions, trace_output);
 
-	if (geteuid()) {
-		err_msg("osnoise needs root permission\n");
-		exit(EXIT_FAILURE);
-	}
+	if (geteuid())
+		fatal("osnoise needs root permission");
 
 	return &params->common;
 }

tools/tracing/rtla/src/timerlat_hist.c

···
 			break;
 		case 'e':
 			tevent = trace_event_alloc(optarg);
-			if (!tevent) {
-				err_msg("Error alloc trace event");
-				exit(EXIT_FAILURE);
-			}
+			if (!tevent)
+				fatal("Error alloc trace event");
 
 			if (params->common.events)
 				tevent->next = params->common.events;
···
 		case 'H':
 			params->common.hk_cpus = 1;
 			retval = parse_cpu_set(optarg, &params->common.hk_cpu_set);
-			if (retval) {
-				err_msg("Error parsing house keeping CPUs\n");
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Error parsing house keeping CPUs");
 			break;
 		case 'i':
 			params->common.stop_us = get_llong_from_str(optarg);
···
 		case '6': /* trigger */
 			if (params->common.events) {
 				retval = trace_event_add_trigger(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding trigger %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding trigger %s", optarg);
 			} else {
 				timerlat_hist_usage("--trigger requires a previous -e\n");
 			}
···
 		case '7': /* filter */
 			if (params->common.events) {
 				retval = trace_event_add_filter(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding filter %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding filter %s", optarg);
 			} else {
 				timerlat_hist_usage("--filter requires a previous -e\n");
 			}
 			break;
 		case '8':
 			params->dma_latency = get_llong_from_str(optarg);
-			if (params->dma_latency < 0 || params->dma_latency > 10000) {
-				err_msg("--dma-latency needs to be >= 0 and < 10000");
-				exit(EXIT_FAILURE);
-			}
+			if (params->dma_latency < 0 || params->dma_latency > 10000)
+				fatal("--dma-latency needs to be >= 0 and < 10000");
 			break;
 		case '9':
 			params->no_aa = 1;
···
 		case '\5':
 			retval = actions_parse(&params->common.threshold_actions, optarg,
 					       "timerlat_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		case '\6':
 			retval = actions_parse(&params->common.end_actions, optarg,
 					       "timerlat_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		default:
-			timerlat_hist_usage("Invalid option");
+			fatal("Invalid option");
 		}
 	}
 
 	if (trace_output)
 		actions_add_trace_output(&params->common.threshold_actions, trace_output);
 
-	if (geteuid()) {
-		err_msg("rtla needs root permission\n");
-		exit(EXIT_FAILURE);
-	}
+	if (geteuid())
+		fatal("rtla needs root permission");
 
 	if (params->common.hist.no_irq && params->common.hist.no_thread)
 		timerlat_hist_usage("no-irq and no-thread set, there is nothing to do here");

tools/tracing/rtla/src/timerlat_top.c

···
 			break;
 		case 'e':
 			tevent = trace_event_alloc(optarg);
-			if (!tevent) {
-				err_msg("Error alloc trace event");
-				exit(EXIT_FAILURE);
-			}
+			if (!tevent)
+				fatal("Error alloc trace event");
 
 			if (params->common.events)
 				tevent->next = params->common.events;
···
 		case 'H':
 			params->common.hk_cpus = 1;
 			retval = parse_cpu_set(optarg, &params->common.hk_cpu_set);
-			if (retval) {
-				err_msg("Error parsing house keeping CPUs\n");
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Error parsing house keeping CPUs");
 			break;
 		case 'i':
 			params->common.stop_us = get_llong_from_str(optarg);
···
 		case '0': /* trigger */
 			if (params->common.events) {
 				retval = trace_event_add_trigger(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding trigger %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding trigger %s", optarg);
 			} else {
 				timerlat_top_usage("--trigger requires a previous -e\n");
 			}
···
 		case '1': /* filter */
 			if (params->common.events) {
 				retval = trace_event_add_filter(params->common.events, optarg);
-				if (retval) {
-					err_msg("Error adding filter %s\n", optarg);
-					exit(EXIT_FAILURE);
-				}
+				if (retval)
+					fatal("Error adding filter %s", optarg);
 			} else {
 				timerlat_top_usage("--filter requires a previous -e\n");
 			}
 			break;
 		case '2': /* dma-latency */
 			params->dma_latency = get_llong_from_str(optarg);
-			if (params->dma_latency < 0 || params->dma_latency > 10000) {
-				err_msg("--dma-latency needs to be >= 0 and < 10000");
-				exit(EXIT_FAILURE);
-			}
+			if (params->dma_latency < 0 || params->dma_latency > 10000)
+				fatal("--dma-latency needs to be >= 0 and < 10000");
 			break;
 		case '3': /* no-aa */
 			params->no_aa = 1;
···
 		case '9':
 			retval = actions_parse(&params->common.threshold_actions, optarg,
 					       "timerlat_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		case '\1':
 			retval = actions_parse(&params->common.end_actions, optarg,
 					       "timerlat_trace.txt");
-			if (retval) {
-				err_msg("Invalid action %s\n", optarg);
-				exit(EXIT_FAILURE);
-			}
+			if (retval)
+				fatal("Invalid action %s", optarg);
 			break;
 		default:
 			timerlat_top_usage("Invalid option");
···
 	if (trace_output)
 		actions_add_trace_output(&params->common.threshold_actions, trace_output);
 
-	if (geteuid()) {
-		err_msg("rtla needs root permission\n");
-		exit(EXIT_FAILURE);
-	}
+	if (geteuid())
+		fatal("rtla needs root permission");
 
 	/*
 	 * Auto analysis only happens if stop tracing, thus:

tools/tracing/rtla/src/timerlat_u.c

···
 
 	if (!params->sched_param) {
 		retval = sched_setscheduler(0, SCHED_FIFO, &sp);
-		if (retval < 0) {
-			err_msg("Error setting timerlat u default priority: %s\n", strerror(errno));
-			exit(1);
-		}
+		if (retval < 0)
+			fatal("Error setting timerlat u default priority: %s", strerror(errno));
 	} else {
 		retval = __set_sched_attr(getpid(), params->sched_param);
 		if (retval) {
···
 	snprintf(buffer, sizeof(buffer), "osnoise/per_cpu/cpu%d/timerlat_fd", cpu);
 
 	timerlat_fd = tracefs_instance_file_open(NULL, buffer, O_RDONLY);
-	if (timerlat_fd < 0) {
-		err_msg("Error opening %s:%s\n", buffer, strerror(errno));
-		exit(1);
-	}
+	if (timerlat_fd < 0)
+		fatal("Error opening %s:%s", buffer, strerror(errno));
 
 	debug_msg("User-space timerlat pid %d on cpu %d\n", gettid(), cpu);
 

tools/tracing/rtla/src/utils.c

···
 }
 
 /*
+ * fatal - print an error message and EOL to stderr and exit with ERROR
+ */
+void fatal(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+
+	exit(ERROR);
+}
+
+/*
  * get_llong_from_str - get a long long int from a string
  */
 long long get_llong_from_str(char *start)

tools/tracing/rtla/src/utils.h

···
 extern int config_debug;
 void debug_msg(const char *fmt, ...);
 void err_msg(const char *fmt, ...);
+void fatal(const char *fmt, ...);
 
 long parse_seconds_duration(char *val);
 void get_duration(time_t start_time, char *output, int output_size);