From patchwork Thu Mar 24 14:14:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lecopzer Chen X-Patchwork-Id: 12790734 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 D3C06C433FE for ; Thu, 24 Mar 2022 14:15:56 +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=cAtFMmT/+EUyBsEvlxMdzAGk0roGRly/A/M+Vg+kH/g=; b=MZhRf41OOHVQkw psrVkMB4+CMVJLrHOkA3qrezbK1eupwPAd5XL9mR8Ez47dEmDlIKnyoC9wjq/p/qKmKIUWivqDVgQ FpB5PEyCYmiobFvobqsBWXaLq7jv6bTqhJNMyRXUP5v8Q2y0EsTpSRxcS1bVHmr4c1CRaQybNU9d7 48g8pD4GpG9NxG2mKr+auE/Vay07TmNlxrP5PYOauo/T+l/OZ1krrUnjMjtdnJMPmYreGZ4SFp2p7 tCYKz5C3fHm0pHvyo79e10XoFItb9LzqmA6Lh3NHWUMOEjskm+OlEAidP0uQmnXVE5U5viE1E/RmF +2B3LY40WC4NoMHy3Zsg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nXOEg-00GoAN-N6; Thu, 24 Mar 2022 14:14:46 +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 1nXOEK-00Gnvz-6r; Thu, 24 Mar 2022 14:14:28 +0000 X-UUID: ebf54bb5d49a47caab0c22bd6dbfc307-20220324 X-UUID: ebf54bb5d49a47caab0c22bd6dbfc307-20220324 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 1757527971; Thu, 24 Mar 2022 07:14:12 -0700 Received: from mtkmbs10n1.mediatek.inc (172.21.101.34) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 24 Mar 2022 07:14:10 -0700 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.15; Thu, 24 Mar 2022 22:14:09 +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, 24 Mar 2022 22:14:08 +0800 From: Lecopzer Chen To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v3 0/5] Support hld delayed init based on Pseudo-NMI for arm64 Date: Thu, 24 Mar 2022 22:14:00 +0800 Message-ID: <20220324141405.10835-1-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-20220324_071424_292748_332D7D60 X-CRM114-Status: GOOD ( 16.53 ) 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() get -EBUSY from arch code, set allow_lockup_detector_init_retry=true 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=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=false. 5. at late_initcall_sync(), lockup_detector_check() call flush_work() first to avoid previous retry_lockup_detector_init() is not scheduled. And then test whether allow_lockup_detector_init_retry is false, if it's true, means we have pending init un-finished, than forcely queue work again and 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/ 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() 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 (4): kernel/watchdog: remove WATCHDOG_DEFAULT kernel/watchdog: change watchdog_nmi_enable() to void kernel/watchdog: Adapt the watchdog_hld interface for async model 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/sparc/kernel/nmi.c | 8 ++-- drivers/perf/arm_pmu.c | 5 +++ include/linux/nmi.h | 5 ++- include/linux/perf/arm_pmu.h | 2 + kernel/watchdog.c | 67 +++++++++++++++++++++++++++++++--- kernel/watchdog_hld.c | 8 +++- 9 files changed, 95 insertions(+), 15 deletions(-)