From patchwork Mon Jun 13 13:59:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lecopzer Chen X-Patchwork-Id: 12879592 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 2AB27C433EF for ; Mon, 13 Jun 2022 14:01:52 +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=Lxyxyb07vkGJt3RQ8f68WEXbwqZr76qh+9iJsLhT3io=; b=Ce2r9vpfiocbHr khDJnEfFl2LetHgtaV1jzKCUfaxD7Fz69A9k00/6yw9d4zkylm0BpFeCcWT26Gys4+Rf/QUptcN+q Wm0j9kIRPf0G+WOIR8Mh9VeIKkF0eLZRICJKsOqX51OGAAu8CURf3yyU9wBFWBpiCaXSd+/YLRAmF LeIq3M8IjTL7p/uU+/ThkXcgMqbvwNQT8MF3ArAosOdTi7YPMupdBVXYzP+Y4UcdgexEFk+EezmaX q6Es/ZpDv1MGhG1jdIMUvV7FhWZxFDjZ/HmANwh3yI4ykjDrhx7j+uT7WOVZ6ma1HLCp86uqY+jbC yzMRsQ4iPZZSy9GsyYLg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o0kcZ-0042Q8-Gl; Mon, 13 Jun 2022 14:00:47 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o0kc3-00429u-Bo; Mon, 13 Jun 2022 14:00:17 +0000 X-UUID: cd65c93951094995ba6d73688012804f-20220613 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.6,REQID:e4583005-dad9-4a33-95da-33ae09a14e1e,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:b14ad71,CLOUDID:1e058f37-84c0-4f9a-9fbd-acd4a0e9ad0f,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:1,File:nil ,QS:nil,BEC:nil,COL:0 X-UUID: cd65c93951094995ba6d73688012804f-20220613 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 570734557; Mon, 13 Jun 2022 07:00:02 -0700 Received: from mtkmbs10n2.mediatek.inc (172.21.101.183) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 13 Jun 2022 07:00:00 -0700 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Mon, 13 Jun 2022 21:59:58 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Mon, 13 Jun 2022 21:59:58 +0800 From: Lecopzer Chen To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v5 0/6] Support hld delayed init based on Pseudo-NMI for Date: Mon, 13 Jun 2022 21:59:50 +0800 Message-ID: <20220613135956.15711-1-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-20220613_070015_485636_238F7A57 X-CRM114-Status: GOOD ( 20.36 ) 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/ v5: 1. rebase on v5.19-rc2 2. change to proper schedule api 3. return value checking before retry_lockup_detector_init() 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 | 12 +++++- 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, 139 insertions(+), 14 deletions(-) create mode 100644 arch/arm64/kernel/watchdog_hld.c