From patchwork Wed Apr 27 16:13:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lecopzer Chen X-Patchwork-Id: 12829246 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 402EAC433F5 for ; Wed, 27 Apr 2022 17:15:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:CC :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=6HSkyvKrwRqaTKKwCY4YCXVxWSlmbYTSg9AfmKkt1yI=; b=MQLq5aFBPdxayg EGCStKGuDArmB3ssGXaKzV4NzGJziSI3GBrBD2XMEmN3+JL37FJdUneJ3+4CV12XJ4/N3I2PScdgS FXCiqvMQm4VjAm+v/V6/VtkztDKkXl6/obtArDBYQr/ttWrcYEddNuGhD3wGBCRGtOI1WabNq18zP 9ocdTrFR30ZkyYabokmKkAUqKODSPVmmd2dDvRHRykoWkq2MzZUP2SX8gaJNatTpK2hBh9OSgE4Aq uSQBt5m2ER2epYOlhdcTDA83vajUpsDmcR+ILIoIDdAVpORDul8KU8xWbVsDupu+iBevb0kIqJNEq RXZzpYWxy1q13pQUtdIw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1njlEf-002ZXD-5R; Wed, 27 Apr 2022 17:13:53 +0000 Received: from mailgw01.mediatek.com ([216.200.240.184]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1njkSP-002HOz-C0; Wed, 27 Apr 2022 16:24:03 +0000 X-UUID: 3cf287d228064b98865496b667c33b23-20220427 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.4, REQID:134e9208-314a-4586-8ad7-ce4c52f8e325, OB:0, LO B:0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,RULE:Release_Ham,ACTI ON:release,TS:0 X-CID-META: VersionHash:faefae9, CLOUDID:3a7bec2e-6199-437e-8ab4-9920b4bc5b76, C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,File:nil,QS:0,BEC:nil X-UUID: 3cf287d228064b98865496b667c33b23-20220427 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 30383077; Wed, 27 Apr 2022 09:23:55 -0700 Received: from mtkexhb02.mediatek.inc (172.21.101.103) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 27 Apr 2022 09:14:03 -0700 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkexhb02.mediatek.inc (172.21.101.103) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 28 Apr 2022 00:13:49 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 28 Apr 2022 00:13:49 +0800 From: Lecopzer Chen To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v4 0/6] Support hld delayed init based on Pseudo-NMI for arm64 Date: Thu, 28 Apr 2022 00:13:34 +0800 Message-ID: <20220427161340.8518-1-lecopzer.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220427_092401_564340_7C8116E8 X-CRM114-Status: GOOD ( 18.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org As we already used hld internally for arm64 since 2020, there still doesn't have a proper commit on the upstream and we badly need it. This serise rework on 5.17 from [1] and the origin author is Pingfan Liu Sumit Garg Qoute from [1]: > Hard lockup detector is helpful to diagnose unpaired irq enable/disable. > But the current watchdog framework can not cope with arm64 hw perf event > easily. > On arm64, when lockup_detector_init()->watchdog_nmi_probe(), PMU is not > ready until device_initcall(armv8_pmu_driver_init). And it is deeply > integrated with the driver model and cpuhp. Hence it is hard to push the > initialization of armv8_pmu_driver_init() before smp_init(). > But it is easy to take an opposite approach by enabling watchdog_hld to > get the capability of PMU async. > The async model is achieved by expanding watchdog_nmi_probe() with > -EBUSY, and a re-initializing work_struct which waits on a > wait_queue_head. Provide an API - retry_lockup_detector_init() for anyone who needs to delayed init lockup detector. The original assumption is: nobody should use delayed probe after lockup_detector_check() (which has __init attribute). That is, anyone uses this API must call between lockup_detector_init() and lockup_detector_check(), and the caller must have __init attribute The delayed init flow is: 1. lockup_detector_init() -> watchdog_nmi_probe() get non-zero retun, then set allow_lockup_detector_init_retry to true which means it's able to do delayed probe later. 2. PMU arch code init done, call retry_lockup_detector_init(). 3. retry_lockup_detector_init() queue the work only when allow_lockup_detector_init_retry is true which means nobody should call this before lockup_detector_init(). 4. the work lockup_detector_delay_init() is doing without wait event. if probe success, set allow_lockup_detector_init_retry to false. 5. at late_initcall_sync(), lockup_detector_check() set allow_lockup_detector_init_retry to false first to avoid any later retry, and then flush_work() to make sure the __init section won't be freed before the work done. [1] https://lore.kernel.org/lkml/20211014024155.15253-1-kernelfans@gmail.com/ v4: 1. remove -EBUSY protocal, let all the non-zero value from watchdog_nmi_probe() be able to retry. 2. separate arm64 part patch into hw_nmi_get_sample_period and retry delayed init 3. tweak commit msg that we don't have to limit to -EBUSY 4. rebase on v5.18-rc4 v3: 1. Tweak commit message in patch 04 2. Remove wait event 3. s/lockup_detector_pending_init/allow_lockup_detector_init_retry/ 4. provide api retry_lockup_detector_init() https://lore.kernel.org/lkml/20220324141405.10835-1-lecopzer.chen@mediatek.com/ v2: 1. Tweak commit message in patch 01/02/04/05 2. Remove vobose WARN in patch 04 within watchdog core. 3. Change from three states variable: detector_delay_init_state to two states variable: allow_lockup_detector_init_retry Thanks Petr Mladek for the idea. > 1. lockup_detector_work() called before lockup_detector_check(). > In this case, wait_event() will wait until lockup_detector_check() > clears detector_delay_pending_init and calls wake_up(). > 2. lockup_detector_check() called before lockup_detector_work(). > In this case, wait_even() will immediately continue because > it will see cleared detector_delay_pending_init. 4. Add comment in code in patch 04/05 for two states variable changing. https://lore.kernel.org/lkml/20220307154729.13477-1-lecopzer.chen@mediatek.com/ Lecopzer Chen (5): kernel/watchdog: remove WATCHDOG_DEFAULT kernel/watchdog: change watchdog_nmi_enable() to void kernel/watchdog: Adapt the watchdog_hld interface for async model arm64: add hw_nmi_get_sample_period for preparation of lockup detector arm64: Enable perf events based hard lockup detector Pingfan Liu (1): kernel/watchdog_hld: Ensure CPU-bound context when creating hardlockup detector event arch/arm64/Kconfig | 2 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/perf_event.c | 10 ++++- arch/arm64/kernel/watchdog_hld.c | 39 +++++++++++++++++ arch/sparc/kernel/nmi.c | 8 ++-- drivers/perf/arm_pmu.c | 5 +++ include/linux/nmi.h | 4 +- include/linux/perf/arm_pmu.h | 2 + kernel/watchdog.c | 72 +++++++++++++++++++++++++++++--- kernel/watchdog_hld.c | 8 +++- 10 files changed, 137 insertions(+), 14 deletions(-) create mode 100644 arch/arm64/kernel/watchdog_hld.c