From patchwork Tue Jun 5 23:53:05 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10449503 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9C67460146 for ; Tue, 5 Jun 2018 23:53:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 83B152882F for ; Tue, 5 Jun 2018 23:53:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7016529262; Tue, 5 Jun 2018 23:53:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 915782882F for ; Tue, 5 Jun 2018 23:53:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966AbeFEXxI (ORCPT ); Tue, 5 Jun 2018 19:53:08 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:38021 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbeFEXxH (ORCPT ); Tue, 5 Jun 2018 19:53:07 -0400 Received: by mail-pg0-f66.google.com with SMTP id c9-v6so2025276pgf.5 for ; Tue, 05 Jun 2018 16:53:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=dcX6rNLHt0dyz3T2X23icFagDVptKGlI3bYsTJ652go=; b=SSjgeWT1hWPjAjDOEHD+JU+w2NHjPCMQkJDP/2EpKAWGJAh1x8ktJZ0ngtytJU9GXZ yft5ZmY75fldFznZPTgcOCaQEommvlg8q5KONPz9Tam0cjY+fdJIk9J29/tUWx80vfw3 gGlVUkM3900Yf3mdl4A6n0O8Y33KiYg17o+NA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=dcX6rNLHt0dyz3T2X23icFagDVptKGlI3bYsTJ652go=; b=CGepajcTP42UfeUatCSK+RFi78KOzf1Ixh4eXB/1b4s0xzq9lv4xetkjtkOFWx01Su p13fMZWKvVSFFDncW60kT7dVtf6AKhfFqItysI63Wjq+O/tqimjzTjusw2paF1QnXFC2 TeErOXEsQa2rVoaevBWTioX8iBTLQA51p0gV4uzKRVKAgB71RsasN/BjiVZudeJpf0UC X/3y7iF0EPWZqbiU0Th00PLr9IRiIqZS2HmZFG3xkJopXSLIZOKyvVukRuBPEaZqtieW Oqoym7CHEfVqvVLoeuz0Lt6G1LIUCtXm1/1U4LCdQE6XQ3hkZan3yO4YRA7O6JmV4jhk B7cA== X-Gm-Message-State: APt69E29TZcjxQRFpar51jNK7qzFlfHyPOPEG8gfpR/+iMORgWZaZHPg bSxo8q3A+vfOzyi74JTS54sS0A== X-Google-Smtp-Source: ADUXVKLPZGYOkU8fhNFEyHI4uAptRPHWV3bGSQqP6gzs/ZnHnPHQuzb/waW3eYDkHStHGbZ0hiowVg== X-Received: by 2002:a62:e310:: with SMTP id g16-v6mr35601pfh.25.1528242786459; Tue, 05 Jun 2018 16:53:06 -0700 (PDT) Received: from localhost ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id l8-v6sm23324711pfb.102.2018.06.05.16.53.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 05 Jun 2018 16:53:05 -0700 (PDT) Date: Tue, 5 Jun 2018 16:53:05 -0700 From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Boqun Feng , Andy Shevchenko , Byungchul Park , Erick Reyes , Ingo Molnar , Julia Cartwright , linux-kselftest@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Paul McKenney , Peter Zijlstra , Shuah Khan , Steven Rostedt , Thomas Glexiner , Todd Kjos , Tom Zanussi Subject: Re: [PATCH v8 7/8] lib: Add module to simulate atomic sections for testing preemptoff tracers Message-ID: <20180605235305.GA72953@joelaf.mtv.corp.google.com> References: <20180530000500.257225-1-joel@joelfernandes.org> <20180530000500.257225-8-joel@joelfernandes.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180530000500.257225-8-joel@joelfernandes.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP (Resending since Andy wasn't on CC - sorry) Hi, On Tue, May 29, 2018 at 05:04:59PM -0700, Joel Fernandes wrote: > From: "Joel Fernandes (Google)" > > In this patch we introduce a test module for simulating a long atomic > section in the kernel which the preemptoff or irqsoff tracers can > detect. This module is to be used only for test purposes and is default > disabled. > > Following is the expected output (only briefly shown) that can be parsed > to verify that the tracers are working correctly. We will use this from > the kselftests in future patches. > > For the preemptoff tracer: > > echo preemptoff > /d/tracing/current_tracer > sleep 1 > insmod ./test_atomic_sections.ko atomic_mode=preempt atomic_time=500000 > sleep 1 > bash-4.3# cat /d/tracing/trace > preempt -1066 2...2 0us@: atomic_sect_run <-atomic_sect_run > preempt -1066 2...2 500002us : atomic_sect_run <-atomic_sect_run > preempt -1066 2...2 500004us : tracer_preempt_on <-atomic_sect_run > preempt -1066 2...2 500012us : > => kthread > => ret_from_fork > > For the irqsoff tracer: > > echo irqsoff > /d/tracing/current_tracer > sleep 1 > insmod ./test_atomic_sections.ko atomic_mode=irq atomic_time=500000 > sleep 1 > bash-4.3# cat /d/tracing/trace > irq dis -1069 1d..1 0us@: atomic_sect_run > irq dis -1069 1d..1 500001us : atomic_sect_run > irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-atomic_sect_run > irq dis -1069 1d..1 500005us : > => ret_from_fork Andy, previously made some suggestions to this patch. The updated version is below and I am planning to send it along with this series as v9. I have included it in advance below for your Review. Andy, would you be Ok with adding your Reviewed-by to it? ---8<----------------------- From: "Joel Fernandes (Google)" Date: Wed, 16 May 2018 23:46:06 -0700 Subject: [PATCH v9 7/8] lib: Add module to simulate atomic sections for testing preemptoff tracers In this patch we introduce a test module for simulating a long atomic section in the kernel which the preemptoff or irqsoff tracers can detect. This module is to be used only for test purposes and is default disabled. Following is the expected output (only briefly shown) that can be parsed to verify that the tracers are working correctly. We will use this from the kselftests in future patches. For the preemptoff tracer: echo preemptoff > /d/tracing/current_tracer sleep 1 insmod ./test_atomic_sections.ko atomic_mode=preempt atomic_time=500000 sleep 1 bash-4.3# cat /d/tracing/trace preempt -1066 2...2 0us@: atomic_sect_run <-atomic_sect_run preempt -1066 2...2 500002us : atomic_sect_run <-atomic_sect_run preempt -1066 2...2 500004us : tracer_preempt_on <-atomic_sect_run preempt -1066 2...2 500012us : => kthread => ret_from_fork For the irqsoff tracer: echo irqsoff > /d/tracing/current_tracer sleep 1 insmod ./test_atomic_sections.ko atomic_mode=irq atomic_time=500000 sleep 1 bash-4.3# cat /d/tracing/trace irq dis -1069 1d..1 0us@: atomic_sect_run irq dis -1069 1d..1 500001us : atomic_sect_run irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-atomic_sect_run irq dis -1069 1d..1 500005us : => ret_from_fork Co-developed-by: Erick Reyes Cc: Andy Shevchenko Signed-off-by: Joel Fernandes (Google) Reviewed-by: Andy Shevchenko --- lib/Kconfig.debug | 8 ++++ lib/Makefile | 1 + lib/test_atomic_sections.c | 77 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 86 insertions(+) create mode 100644 lib/test_atomic_sections.c diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c40c7b734cd1..faebf0fe3bcf 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1933,6 +1933,14 @@ config TEST_KMOD If unsure, say N. +config TEST_ATOMIC_SECTIONS + tristate "Simulate atomic sections for tracers to detect" + depends on m + help + Select this option to build a test module that can help test atomic + sections by simulating them with a duration supplied as a module + parameter. Preempt disable and irq disable modes can be requested. + config TEST_DEBUG_VIRTUAL tristate "Test CONFIG_DEBUG_VIRTUAL feature" depends on DEBUG_VIRTUAL diff --git a/lib/Makefile b/lib/Makefile index ce20696d5a92..e82cf5445b7b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -46,6 +46,7 @@ obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o obj-y += hexdump.o obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o +obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o obj-y += kstrtox.o obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o obj-$(CONFIG_TEST_BPF) += test_bpf.o diff --git a/lib/test_atomic_sections.c b/lib/test_atomic_sections.c new file mode 100644 index 000000000000..1eef518f0974 --- /dev/null +++ b/lib/test_atomic_sections.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Atomic section emulation test module + * + * Emulates atomic sections by disabling IRQs or preemption + * and doing a busy wait for a specified amount of time. + * This can be used for testing of different atomic section + * tracers such as irqsoff tracers. + * + * (c) 2018. Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static ulong atomic_time = 100; +static char atomic_mode[10] = "irq"; + +module_param_named(atomic_time, atomic_time, ulong, S_IRUGO); +module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO); +MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)"); +MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)"); + +static void busy_wait(ulong time) +{ + ktime_t start, end; + start = ktime_get(); + do { + end = ktime_get(); + if (kthread_should_stop()) + break; + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); +} + +int atomic_sect_run(void *data) +{ + unsigned long flags; + + if (!strcmp(atomic_mode, "irq")) { + local_irq_save(flags); + busy_wait(atomic_time); + local_irq_restore(flags); + } else if (!strcmp(atomic_mode, "preempt")) { + preempt_disable(); + busy_wait(atomic_time); + preempt_enable(); + } + + return 0; +} + +static int __init atomic_sect_init(void) +{ + char task_name[50]; + struct task_struct *test_task; + + snprintf(task_name, sizeof(task_name), "%s_test", atomic_mode); + + test_task = kthread_run(atomic_sect_run, NULL, task_name); + return PTR_ERR_OR_ZERO(test_task); +} + +static void __exit atomic_sect_exit(void) +{ + return; +} + +module_init(atomic_sect_init) +module_exit(atomic_sect_exit) +MODULE_LICENSE("GPL v2");