linux-kernel - [PATCH v3 14/18] rtla/timerlat: Simplify RTLA_NO

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Message-ID: <20260115163650.118910-15-wander@redhat.com>
Date: Thu, 15 Jan 2026 13:31:57 -0300
From: Wander Lairson Costa <wander@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Tomas Glozar <tglozar@...hat.com>,
	Wander Lairson Costa <wander@...hat.com>,
	Crystal Wood <crwood@...hat.com>,
	Ivan Pravdin <ipravdin.official@...il.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>,
	Daniel Wagner <dwagner@...e.de>,
	Daniel Bristot de Oliveira <bristot@...nel.org>,
	linux-trace-kernel@...r.kernel.org (open list:Real-time Linux Analysis (RTLA) tools),
	linux-kernel@...r.kernel.org (open list:Real-time Linux Analysis (RTLA) tools),
	bpf@...r.kernel.org (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_))
Subject: [PATCH v3 14/18] rtla/timerlat: Simplify RTLA_NO_BPF environment variable check

The code that checks the RTLA_NO_BPF environment variable calls
getenv() twice and uses strncmp() with a length of 2 to compare
against the single-character string "1". This is inefficient and
the comparison length is unnecessarily long.

Store the result of getenv() in a local variable to avoid the
redundant call, and replace strncmp() with strcmp() for the exact
match comparison. This follows the same pattern established in
recent commits that improved string comparison consistency
throughout the rtla codebase.

Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
 tools/tracing/rtla/src/timerlat.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/src/timerlat.c b/tools/tracing/rtla/src/timerlat.c
index 84577daadd668..d7aeaad975386 100644
--- a/tools/tracing/rtla/src/timerlat.c
+++ b/tools/tracing/rtla/src/timerlat.c
@@ -28,12 +28,13 @@ int
 timerlat_apply_config(struct osnoise_tool *tool, struct timerlat_params *params)
 {
 	int retval;
+	const char *const rtla_no_bpf = getenv("RTLA_NO_BPF");
 
 	/*
 	 * 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 (rtla_no_bpf && strcmp(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")) {
-- 
2.52.0