From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
To: Jonathan Corbet <corbet@lwn.net>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Shuah Khan <shuah@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: [PATCH 2/2] selftests/ftrace: Add test case for overriding trace_instance parameter
Date: Sat, 19 Sep 2026 23:38:36 +0900 [thread overview]
Message-ID: <178982871684.289221.11881705926508561494.stgit@devnote2> (raw)
In-Reply-To: <178982869661.289221.2143320719673148321.stgit@devnote2>
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a boot-time tracing test case to verify that specifying multiple
trace_instance= parameters with the same instance name overrides earlier
definitions:
- Verifies that a kernel command-line trace_instance= parameter
overrides an earlier trace instance defined via bootconfig
(kernel.trace_instance).
- Verifies that a latter kernel command-line trace_instance=
parameter overrides an earlier trace_instance= on the same
command line.
- Confirms that the overridden instance has its previous events
disabled, new events enabled, and flags (such as traceoff)
properly applied.
Assisted-by: Antigravity:gemini-3.8-flash
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
.../cmdline-07-trace-instance-override.bconf | 2 +
.../cmdline-07-trace-instance-override.cmdline | 1
.../tests/cmdline-07-trace-instance-override.sh | 56 ++++++++++++++++++++
3 files changed, 59 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/boottime/bootconfigs/cmdline-07-trace-instance-override.bconf
create mode 100644 tools/testing/selftests/ftrace/boottime/cmdlines/cmdline-07-trace-instance-override.cmdline
create mode 100644 tools/testing/selftests/ftrace/boottime/tests/cmdline-07-trace-instance-override.sh
diff --git a/tools/testing/selftests/ftrace/boottime/bootconfigs/cmdline-07-trace-instance-override.bconf b/tools/testing/selftests/ftrace/boottime/bootconfigs/cmdline-07-trace-instance-override.bconf
new file mode 100644
index 000000000000..2551da39f722
--- /dev/null
+++ b/tools/testing/selftests/ftrace/boottime/bootconfigs/cmdline-07-trace-instance-override.bconf
@@ -0,0 +1,2 @@
+kernel.trace_instance = "foo,sched:sched_switch"
+
diff --git a/tools/testing/selftests/ftrace/boottime/cmdlines/cmdline-07-trace-instance-override.cmdline b/tools/testing/selftests/ftrace/boottime/cmdlines/cmdline-07-trace-instance-override.cmdline
new file mode 100644
index 000000000000..1953eb5d6f80
--- /dev/null
+++ b/tools/testing/selftests/ftrace/boottime/cmdlines/cmdline-07-trace-instance-override.cmdline
@@ -0,0 +1 @@
+trace_instance=foo^traceoff,sched:sched_waking trace_instance=bar,sched:sched_switch trace_instance=bar^traceoff,irq:irq_handler_entry
diff --git a/tools/testing/selftests/ftrace/boottime/tests/cmdline-07-trace-instance-override.sh b/tools/testing/selftests/ftrace/boottime/tests/cmdline-07-trace-instance-override.sh
new file mode 100644
index 000000000000..a13b7deb6735
--- /dev/null
+++ b/tools/testing/selftests/ftrace/boottime/tests/cmdline-07-trace-instance-override.sh
@@ -0,0 +1,56 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2026, Google LLC.
+# Check trace_instance= override with bootconfig and kernel command-line
+TRACEDIR="/sys/kernel/tracing"
+
+if [ -f /proc/bootconfig ] && grep -q "dump_bconf" /proc/cmdline 2>/dev/null; then
+ echo "=== /proc/bootconfig ==="
+ cat /proc/bootconfig
+ echo "========================"
+fi
+
+check_instance() {
+ instance="$1"
+ old_event="$2"
+ new_event="$3"
+
+ if [ ! -d "$TRACEDIR/instances/$instance" ]; then
+ echo "FAIL: trace instance $instance does not exist"
+ exit 1
+ fi
+
+ if [ -f "$TRACEDIR/instances/$instance/events/$old_event/enable" ]; then
+ ENABLE=$(cat "$TRACEDIR/instances/$instance/events/$old_event/enable")
+ if [ "$ENABLE" = "1" ]; then
+ echo "FAIL: overridden event $old_event is still enabled in instance $instance"
+ exit 1
+ fi
+ fi
+
+ if [ ! -d "$TRACEDIR/instances/$instance/events/$new_event" ]; then
+ echo "FAIL: event $new_event does not exist in instance $instance"
+ exit 1
+ fi
+
+ ENABLE=$(cat "$TRACEDIR/instances/$instance/events/$new_event/enable")
+ if [ "$ENABLE" != "1" ]; then
+ echo "FAIL: event $new_event is not enabled in instance $instance ($ENABLE)"
+ exit 1
+ fi
+
+ TRACING_ON=$(cat "$TRACEDIR/instances/$instance/tracing_on")
+ if [ "$TRACING_ON" != "0" ]; then
+ echo "FAIL: tracing_on is not 0 in instance $instance ($TRACING_ON)"
+ exit 1
+ fi
+}
+
+# Test 1: bootconfig trace_instance overridden by cmdline parameter
+check_instance "foo" "sched/sched_switch" "sched/sched_waking"
+
+# Test 2: cmdline trace_instance overridden by subsequent cmdline parameter
+check_instance "bar" "sched/sched_switch" "irq/irq_handler_entry"
+
+echo "PASS: cmdline-07-trace-instance-override"
+exit 0
prev parent reply other threads:[~2026-09-19 14:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-19 14:38 [PATCH 0/2] tracing: Override " Masami Hiramatsu (Google)
2026-09-19 14:38 ` [PATCH 1/2] tracing: Override the same name trace_instance= by latter one Masami Hiramatsu (Google)
2026-09-19 14:38 ` Masami Hiramatsu (Google) [this message]
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