linux-kernel - [PATCH v3 11/18] rtla: Use str_has

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Message-ID: <20260115163650.118910-12-wander@redhat.com>
Date: Thu, 15 Jan 2026 13:31:54 -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 11/18] rtla: Use str_has_prefix() for prefix checks

The code currently uses strncmp() combined with strlen() to check if a
string starts with a specific prefix. This pattern is verbose and prone
to errors if the length does not match the prefix string.

Replace this pattern with the str_has_prefix() helper function in both
trace.c and utils.c. This improves code readability and safety by
handling the prefix length calculation automatically.

In addition, remove the unused retval variable from
trace_event_save_hist() in trace.c to clean up the function and
silence potential compiler warnings.

Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
 tools/tracing/rtla/src/trace.c | 5 ++---
 tools/tracing/rtla/src/utils.c | 3 +--
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/tools/tracing/rtla/src/trace.c b/tools/tracing/rtla/src/trace.c
index 2f529aaf8deef..ed7db5f4115ce 100644
--- a/tools/tracing/rtla/src/trace.c
+++ b/tools/tracing/rtla/src/trace.c
@@ -342,7 +342,7 @@ static void trace_event_disable_filter(struct trace_instance *instance,
 static void trace_event_save_hist(struct trace_instance *instance,
 				  struct trace_events *tevent)
 {
-	int retval, index, out_fd;
+	int index, out_fd;
 	mode_t mode = 0644;
 	char path[MAX_PATH];
 	char *hist;
@@ -356,8 +356,7 @@ static void trace_event_save_hist(struct trace_instance *instance,
 		return;
 
 	/* is this a hist: trigger? */
-	retval = strncmp(tevent->trigger, "hist:", strlen("hist:"));
-	if (retval)
+	if (!str_has_prefix(tevent->trigger, "hist:"))
 		return;
 
 	snprintf(path, ARRAY_SIZE(path), "%s_%s_hist.txt", tevent->system, tevent->event);
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index e98288e55db15..486d96e8290fb 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -318,8 +318,7 @@ static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_e
 		return 0;
 
 	buffer[MAX_PATH-1] = '\0';
-	retval = strncmp(comm_prefix, buffer, strlen(comm_prefix));
-	if (retval)
+	if (!str_has_prefix(buffer, comm_prefix))
 		return 0;
 
 	/* comm already have \n */
-- 
2.52.0