From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 014D32D7DC6; Sat, 19 Sep 2026 14:38:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789828703; cv=none; b=PjuXzUq/YHSaIIXMegpc8azZL6mc001xhXFsN5K3AU8+DZ64qS+NNSOcIFVybqWKezLW/aVpGM+bun5Hp+T3Th0oa78MBtGSfLQBYOPw1elY7sDgiua/rAIY7TgkwF3lKWDxfF1k2kA8YeTM3MtUk1asI1R0t4HyUY1fIJdtIcA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789828703; c=relaxed/simple; bh=ZG/lbqdTzFGaQFxKi4UzQSfafZtlh1LxnqaiYUObSFA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=diWqH153o87iBYMJJt7BMUT/VLc83wOT9ixBSclUT4Q/7dphAR4nZfc47yzytbBhh856JvoEuz2KQLOqQbV58qNbtIjo/DPPwS+CLO7EQIrVlwgUwQRv7SLarW8pBqhZTaELu6NAcoFHnmNx6pRWvne3/vDOa5XncP8ClEL51SY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=heTMxLEe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="heTMxLEe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C26C1F000FF; Sat, 19 Sep 2026 14:38:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789828701; bh=Ye5WbKjKFgkqarhBNRF073Cdbb5tflcWG8IEwR1LEuk=; h=From:To:Cc:Subject:Date; b=heTMxLEeMBgy0w7Wxjh+VA34+suUXXAMK1aIMFooksiCr0ru0Z6Ait3WeidESrT23 1UmvPqBKhvt7LwqRvsMA1DqJtJ53DsmmXsVABZNjQz9lkz3FTN5lg8q5XY1+TiwAiU Qz59ugb/oOKRQ65QG10XzypTM7k/iMNnwsmVmSb15sqWvQ64trs7IJA7J/kE9T1JQx D2+nVNEMiGFGMvMRRg7nK24zeMHsQL2uuTc2GseSNvY2JiN7zQ9c4ZksSPCiP4KVNF NdX+U9xWLuNNz/psGU0z2nJRDzrshoZPeJmSEChw/e6VXSOoGQyrZfoc6wkT6XKFvy WryK7B15Eitvw== From: "Masami Hiramatsu (Google)" To: Jonathan Corbet , Steven Rostedt , Masami Hiramatsu , Shuah Khan Cc: Shuah Khan , Mathieu Desnoyers , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH 0/2] tracing: Override trace_instance parameter Date: Sat, 19 Sep 2026 23:38:16 +0900 Message-ID: <178982869661.289221.2143320719673148321.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Hi, This changes the trace_instance= kernel parameter to be overriden by latter parameters. Currently if the user specifies the same name trace_instance at boot time, the later one is skipped. However, this does not allow user to override the trace_instance setting via bootloader if user specifies the default trace_instance in the bootconfig, because the bootconfig parameter is prepend to the kernel cmdline. (IOW, the bootconfig expects kernel parameters are LAST_WIN policy.) To fix this issue, the [1/2] splits the command line parsing loop and trace instance initialization loop. The parser checks the overlap of the trace instance name and override by the later one if those have the same name. This series also have a test set as [2/2], which is based on ftrace boottime test patchset [1], which is currently on probes/core branch. (Steve, can you review the boottime test series too? I think we should have this kind of test anyway, and is nicer to have one in the kernel tree.) [1] https://lore.kernel.org/all/178649540853.438282.4271870161169100680.stgit@devnote2/ Thank you, --- Masami Hiramatsu (Google) (2): tracing: Override the same name trace_instance= by latter one selftests/ftrace: Add test case for overriding trace_instance parameter Documentation/admin-guide/kernel-parameters.txt | 7 + Documentation/trace/debugging.rst | 15 ++ kernel/trace/trace.c | 127 +++++++++++++++----- .../cmdline-07-trace-instance-override.bconf | 2 .../cmdline-07-trace-instance-override.cmdline | 1 .../tests/cmdline-07-trace-instance-override.sh | 56 +++++++++ 6 files changed, 174 insertions(+), 34 deletions(-) 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 -- Masami Hiramatsu (Google)