From patchwork Tue Jan 21 16:21:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 215163 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49F6CC2D0CE for ; Tue, 21 Jan 2020 16:22:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 204B624656 for ; Tue, 21 Jan 2020 16:22:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="D8GxvoTM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729276AbgAUQVy (ORCPT ); Tue, 21 Jan 2020 11:21:54 -0500 Received: from mail-wr1-f66.google.com ([209.85.221.66]:41179 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726555AbgAUQVy (ORCPT ); Tue, 21 Jan 2020 11:21:54 -0500 Received: by mail-wr1-f66.google.com with SMTP id c9so3902076wrw.8 for ; Tue, 21 Jan 2020 08:21:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=c83oVOuqImIzXQyusYFsofs6lDjrmtrJIiJurwz27sw=; b=D8GxvoTMOQgJS2L0yLABhKKzcjx3RI9HH6JWxyE4P9nV1BwoWiO04bRfOtLMz1PODH seh04IQ7Pu60ulwxRjc6hyxFLo+gl7venIbx/pU66InLu/YulRjnaM3f7eEX7Fy54Ns7 ZdoK//AeAw9yub5TEn43LjdLvdx4e5vX527mg0N8O+rch6zt+57C10obLivW5M51deIe WemzikzT3sJN3U3YocaDffFsY8rQH3rXYH+8+BFw141Mqc6tG9whYG3AqD4mwE6uWfU9 tREaQ831UcAXG2HdSPysYm1YOXezVZQDZ0x42ukqAOCCdkPtPrjbNpSiVVys9MCjyKg9 3/YQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=c83oVOuqImIzXQyusYFsofs6lDjrmtrJIiJurwz27sw=; b=rVjJZLqO7dNxM/8fsN1sffo7q0vWFbJadhg9IyZf0i4mz2J6tkoILHqyy2ojIuRSzZ khoaMbz4XPHvVArBL/DkRWJphIro1Y7PWzg32F7lXZaBrLnnobii//c4ZgMQSAKsnf1b IXB+lN9LZ1WwjrpFPvnBzvo7ES9tBTmrd4Vrs4/iAacV+AYRRALCGpowDs3D/V4wKwD/ CgXTV0b/kXYzzYq3Dk6wwuc2PbzLqIcA4ubYRYJw6x63sqe5GxvrrRBD0LxSz1/AOzqj +Cle7ux+hCEOzuNufEH0PiuhfT+k0iVd6H/rOZoC05mKUoxXXZQc4Nm0fh4MBpj8nwja qB2A== X-Gm-Message-State: APjAAAVz1Xw3cIVeOTghvhv5Zvk2mQ3svko5ELAaD99/K6ysL46e4xGB vBdFfCajzdmvZdPhRvWI/9L+dA== X-Google-Smtp-Source: APXvYqzv+PoYIaDtjKouci7MtJ3WSfyi/kOcDGlFoBlFJzHC+sxJytfWm0QSaIuHgif2iEMvCvR1sQ== X-Received: by 2002:a5d:6b47:: with SMTP id x7mr6187916wrw.277.1579623712652; Tue, 21 Jan 2020 08:21:52 -0800 (PST) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id k8sm52454388wrl.3.2020.01.21.08.21.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jan 2020 08:21:51 -0800 (PST) From: Dmitry Safonov To: linux-kernel@vger.kernel.org Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Dmitry Safonov , Guenter Roeck , Wim Van Sebroeck , linux-watchdog@vger.kernel.org Subject: [RFC 1/2] watchdog: Check WDOG_STOP_ON_REBOOT in reboot notifier Date: Tue, 21 Jan 2020 16:21:44 +0000 Message-Id: <20200121162145.166334-2-dima@arista.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200121162145.166334-1-dima@arista.com> References: <20200121162145.166334-1-dima@arista.com> MIME-Version: 1.0 Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org Many watchdog drivers use watchdog_stop_on_reboot() helper in order to stop the watchdog on system reboot. Unfortunately, this logic is coded in driver's probe function and doesn't allows user to decide what to do during shutdown/reboot. On the other side, Xen and Qemu watchdog drivers (xen_wdt and i6300esb) may be configured to either send NMI or turn off/reboot VM as the watchdog action. As the kernel may stuck at any state, sending NMIs can't reliably reboot the VM. At Arista, we benefited from the following set-up: the emulated watchdogs trigger VM reset and softdog is set to catch less severe conditions to generate vmcore. Just before reboot watchdog's timeout is increased to some good-enough value (3 mins). That keeps watchdog always running and guarantees that VM doesn't stuck. As a preparation to move the watchdog's decision to stop on reboot or not in userspace, allow WDOG_STOP_ON_REBOOT to be set during runtime, not only on driver's probing. Always register reboot notifier and check WDOG_STOP_ON_REBOOT inside it (on actual reboot). Signed-off-by: Dmitry Safonov --- drivers/watchdog/watchdog_dev.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 4b2a85438478..8766dd93028f 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -1103,6 +1103,10 @@ static int watchdog_reboot_notifier(struct notifier_block *nb, struct watchdog_device *wdd; wdd = container_of(nb, struct watchdog_device, reboot_nb); + + if (!test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) + return NOTIFY_DONE; + if (code == SYS_DOWN || code == SYS_HALT) { if (watchdog_active(wdd)) { int ret; @@ -1139,16 +1143,13 @@ int watchdog_dev_register(struct watchdog_device *wdd) return ret; } - if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { - wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; + wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; - ret = devm_register_reboot_notifier(&wdd->wd_data->dev, - &wdd->reboot_nb); - if (ret) { - pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", - wdd->id, ret); - watchdog_dev_unregister(wdd); - } + ret = devm_register_reboot_notifier(&wdd->wd_data->dev, &wdd->reboot_nb); + if (ret) { + pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", + wdd->id, ret); + watchdog_dev_unregister(wdd); } return ret;