linux-kernel - [PATCH v2 3/5] tools/rtla: Replace timerlat_hist

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Message-ID: <20251011082738.173670-4-costa.shul@redhat.com>
Date: Sat, 11 Oct 2025 11:27:36 +0300
From: Costa Shulyupin <costa.shul@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Tomas Glozar <tglozar@...hat.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	Crystal Wood <crwood@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>,
	linux-trace-kernel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/5] tools/rtla: Replace timerlat_hist_usage("...") with fatal("...")

A long time ago, when the usage help was short, it was a favor
to the user to show it on error. Now that the usage help has
become very long, it is too noisy to dump the complete help text
for each typo after the error message itself.

Replace timerlat_hist_usage("...\n") with fatal("...") on errors.

Remove the already unused 'usage' argument from timerlat_hist_usage().

Signed-off-by: Costa Shulyupin <costa.shul@...hat.com>

---

Changes since v1:
- fatal() prints "\n" insteasd of caller as suggested by Crystal Wood
---
 tools/tracing/rtla/src/timerlat_hist.c | 32 +++++++++++---------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index ab5d8ca4593c..71557f5751a6 100644
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -710,7 +710,7 @@ timerlat_print_stats(struct osnoise_tool *tool)
 /*
  * timerlat_hist_usage - prints timerlat top usage message
  */
-static void timerlat_hist_usage(char *usage)
+static void timerlat_hist_usage(void)
 {
 	int i;
 
@@ -766,18 +766,12 @@ static void timerlat_hist_usage(char *usage)
 		NULL,
 	};
 
-	if (usage)
-		fprintf(stderr, "%s\n", usage);
-
 	fprintf(stderr, "rtla timerlat hist: a per-cpu histogram of the timer latency (version %s)\n",
 			VERSION);
 
 	for (i = 0; msg[i]; i++)
 		fprintf(stderr, "%s\n", msg[i]);
 
-	if (usage)
-		exit(EXIT_FAILURE);
-
 	exit(EXIT_SUCCESS);
 }
 
@@ -884,7 +878,7 @@ static struct common_params
 		case 'c':
 			retval = parse_cpu_set(optarg, &params->common.monitored_cpus);
 			if (retval)
-				timerlat_hist_usage("\nInvalid -c cpu list\n");
+				fatal("Invalid -c cpu list");
 			params->common.cpus = optarg;
 			break;
 		case 'C':
@@ -901,7 +895,7 @@ static struct common_params
 			params->common.hist.bucket_size = get_llong_from_str(optarg);
 			if (params->common.hist.bucket_size == 0 ||
 			    params->common.hist.bucket_size >= 1000000)
-				timerlat_hist_usage("Bucket size needs to be > 0 and <= 1000000\n");
+				fatal("Bucket size needs to be > 0 and <= 1000000");
 			break;
 		case 'D':
 			config_debug = 1;
@@ -909,7 +903,7 @@ static struct common_params
 		case 'd':
 			params->common.duration = parse_seconds_duration(optarg);
 			if (!params->common.duration)
-				timerlat_hist_usage("Invalid -D duration\n");
+				fatal("Invalid -D duration");
 			break;
 		case 'e':
 			tevent = trace_event_alloc(optarg);
@@ -925,11 +919,11 @@ static struct common_params
 			params->common.hist.entries = get_llong_from_str(optarg);
 			if (params->common.hist.entries < 10 ||
 			    params->common.hist.entries > 9999999)
-				timerlat_hist_usage("Entries must be > 10 and < 9999999\n");
+				fatal("Entries must be > 10 and < 9999999");
 			break;
 		case 'h':
 		case '?':
-			timerlat_hist_usage(NULL);
+			timerlat_hist_usage();
 			break;
 		case 'H':
 			params->common.hk_cpus = 1;
@@ -949,12 +943,12 @@ static struct common_params
 		case 'p':
 			params->timerlat_period_us = get_llong_from_str(optarg);
 			if (params->timerlat_period_us > 1000000)
-				timerlat_hist_usage("Period longer than 1 s\n");
+				fatal("Period longer than 1 s");
 			break;
 		case 'P':
 			retval = parse_prio(optarg, &params->common.sched_param);
 			if (retval == -1)
-				timerlat_hist_usage("Invalid -P priority");
+				fatal("Invalid -P priority");
 			params->common.set_sched = 1;
 			break;
 		case 's':
@@ -1004,7 +998,7 @@ static struct common_params
 				if (retval)
 					fatal("Error adding trigger %s", optarg);
 			} else {
-				timerlat_hist_usage("--trigger requires a previous -e\n");
+				fatal("--trigger requires a previous -e");
 			}
 			break;
 		case '7': /* filter */
@@ -1013,7 +1007,7 @@ static struct common_params
 				if (retval)
 					fatal("Error adding filter %s", optarg);
 			} else {
-				timerlat_hist_usage("--filter requires a previous -e\n");
+				fatal("--filter requires a previous -e");
 			}
 			break;
 		case '8':
@@ -1060,10 +1054,10 @@ static struct common_params
 		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");
+		fatal("no-irq and no-thread set, there is nothing to do here");
 
 	if (params->common.hist.no_index && !params->common.hist.with_zeros)
-		timerlat_hist_usage("no-index set with with-zeros is not set - it does not make sense");
+		fatal("no-index set with with-zeros is not set - it does not make sense");
 
 	/*
 	 * Auto analysis only happens if stop tracing, thus:
@@ -1072,7 +1066,7 @@ static struct common_params
 		params->no_aa = 1;
 
 	if (params->common.kernel_workload && params->common.user_workload)
-		timerlat_hist_usage("--kernel-threads and --user-threads are mutually exclusive!");
+		fatal("--kernel-threads and --user-threads are mutually exclusive!");
 
 	/*
 	 * If auto-analysis or trace output is enabled, switch from BPF mode to
-- 
2.51.0