linux-kernel - [rtla 06/13] rtla: Use strncmp

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Message-ID: <20251117184409.42831-7-wander@redhat.com>
Date: Mon, 17 Nov 2025 15:41:13 -0300
From: Wander Lairson Costa <wander@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Wander Lairson Costa <wander@...hat.com>,
	Tomas Glozar <tglozar@...hat.com>,
	Ivan Pravdin <ipravdin.official@...il.com>,
	Crystal Wood <crwood@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>,
	linux-trace-kernel@...r.kernel.org (open list:Real-time Linux Analysis (RTLA) tools),
	linux-kernel@...r.kernel.org (open list),
	bpf@...r.kernel.org (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_))
Subject: [rtla 06/13] rtla: Use strncmp_static() in more places

The recently introduced strncmp_static() helper provides a safer way
to compare strings with static strings by determining the length at
compile time.

Replace several open-coded strncmp() calls with strncmp_static() to
improve code readability and robustness. This change affects the
parsing of command-line arguments and environment variables.

Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
 tools/tracing/rtla/src/osnoise.c  | 2 +-
 tools/tracing/rtla/src/timerlat.c | 4 ++--
 tools/tracing/rtla/src/trace.c    | 2 +-
 tools/tracing/rtla/src/utils.c    | 8 ++++----
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/tools/tracing/rtla/src/osnoise.c b/tools/tracing/rtla/src/osnoise.c
index 312c511fa0044..5075e0f485c77 100644
--- a/tools/tracing/rtla/src/osnoise.c
+++ b/tools/tracing/rtla/src/osnoise.c
@@ -1229,7 +1229,7 @@ int osnoise_main(int argc, char *argv[])
 
 	if ((strcmp(argv[1], "-h") == 0) || (strcmp(argv[1], "--help") == 0)) {
 		osnoise_usage(0);
-	} else if (strncmp(argv[1], "-", 1) == 0) {
+	} else if (strncmp_static(argv[1], "-") == 0) {
 		/* the user skipped the tool, call the default one */
 		run_tool(&osnoise_top_ops, argc, argv);
 		exit(0);
diff --git a/tools/tracing/rtla/src/timerlat.c b/tools/tracing/rtla/src/timerlat.c
index b692128741279..56e0b8af041d7 100644
--- a/tools/tracing/rtla/src/timerlat.c
+++ b/tools/tracing/rtla/src/timerlat.c
@@ -34,7 +34,7 @@ timerlat_apply_config(struct osnoise_tool *tool, struct timerlat_params *params)
 	 * Try to enable BPF, unless disabled explicitly.
 	 * If BPF enablement fails, fall back to tracefs mode.
 	 */
-	if (getenv("RTLA_NO_BPF") && strncmp(getenv("RTLA_NO_BPF"), "1", 2) == 0) {
+	if (getenv("RTLA_NO_BPF") && strncmp_static(getenv("RTLA_NO_BPF"), "1") == 0) {
 		debug_msg("RTLA_NO_BPF set, disabling BPF\n");
 		params->mode = TRACING_MODE_TRACEFS;
 	} else if (!tep_find_event_by_name(tool->trace.tep, "osnoise", "timerlat_sample")) {
@@ -275,7 +275,7 @@ int timerlat_main(int argc, char *argv[])
 
 	if ((strcmp(argv[1], "-h") == 0) || (strcmp(argv[1], "--help") == 0)) {
 		timerlat_usage(0);
-	} else if (strncmp(argv[1], "-", 1) == 0) {
+	} else if (strncmp_static(argv[1], "-") == 0) {
 		/* the user skipped the tool, call the default one */
 		run_tool(&timerlat_top_ops, argc, argv);
 		exit(0);
diff --git a/tools/tracing/rtla/src/trace.c b/tools/tracing/rtla/src/trace.c
index 69cbc48d53d3a..813f4368f104b 100644
--- a/tools/tracing/rtla/src/trace.c
+++ b/tools/tracing/rtla/src/trace.c
@@ -372,7 +372,7 @@ static void trace_event_save_hist(struct trace_instance *instance,
 		return;
 
 	/* is this a hist: trigger? */
-	retval = strncmp(tevent->trigger, "hist:", strlen("hist:"));
+	retval = strncmp_static(tevent->trigger, "hist:");
 	if (retval)
 		return;
 
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 4cb765b94feec..f13d00d7b6bfe 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -196,15 +196,15 @@ long parse_ns_duration(char *val)
 	t = strtol(val, &end, 10);
 
 	if (end) {
-		if (!strncmp(end, "ns", 2)) {
+		if (!strncmp_static(end, "ns")) {
 			return t;
-		} else if (!strncmp(end, "us", 2)) {
+		} else if (!strncmp_static(end, "us")) {
 			t *= 1000;
 			return t;
-		} else if (!strncmp(end, "ms", 2)) {
+		} else if (!strncmp_static(end, "ms")) {
 			t *= 1000 * 1000;
 			return t;
-		} else if (!strncmp(end, "s", 1)) {
+		} else if (!strncmp_static(end, "s")) {
 			t *= 1000 * 1000 * 1000;
 			return t;
 		}
-- 
2.51.1