From owner-freebsd-stable@FreeBSD.ORG Fri Jul 27 14:42:51 2012 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5CE50106566C; Fri, 27 Jul 2012 14:42:51 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from mail-lb0-f182.google.com (mail-lb0-f182.google.com [209.85.217.182]) by mx1.freebsd.org (Postfix) with ESMTP id 2F0B68FC0A; Fri, 27 Jul 2012 14:42:49 +0000 (UTC) Received: by lbon10 with SMTP id n10so2742962lbo.13 for ; Fri, 27 Jul 2012 07:42:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:reply-to:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=JaGNKxMqgDphkuc7wtBsVhFHt0UD0wLnZ5outS0LjLE=; b=UyLvGdJsqph6W5iReHJeyICJSdeadCD5VxTyk9sWKBpAtAxl1T1JSGknmQH+afMUer PpTEjw9KEGXCQsMIu+XalWAdXwsDu8frgGAtsh1Q72S/rdVEOb/0ojB9nv1zCltle7m8 skLKQy3JsyELuCJ3Hxk+SQJQg2OJL+ZJatnlDZJiXUJXy8MRSsH1PfaWxxkfL6RGdIb8 Jwf4Bpd0OvZB1/mUnMQqb7xHyKgoWtZcSKIXmhatEYVe9VaIV3ehlU5HA4iLL0xheSY+ pW+KiPqSlcrWCIbqsEE3W3eh+l9zypnkDnPQxeKW28ckEdzW3JnDjHhFKvv/jqzQNS2t Ck0g== MIME-Version: 1.0 Received: by 10.152.46.6 with SMTP id r6mr2896597lam.7.1343400169071; Fri, 27 Jul 2012 07:42:49 -0700 (PDT) Sender: asmrookie@gmail.com Received: by 10.112.27.65 with HTTP; Fri, 27 Jul 2012 07:42:49 -0700 (PDT) In-Reply-To: <23294764-F30B-4732-8C41-3F0ECA5F273C@averesystems.com> References: <1343350238.12294.10.camel@powernoodle.corp.yahoo.com> <23294764-F30B-4732-8C41-3F0ECA5F273C@averesystems.com> Date: Fri, 27 Jul 2012 15:42:49 +0100 X-Google-Sender-Auth: WpCJ8KZjBSWJMMwUoif1GVRODE4 Message-ID: From: Attilio Rao To: Andrew Boyer Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: FreeBSD Stable Mailing List , John Baldwin , Andriy Gapon Subject: Re: IPMI hardware watchdogs Re: dell r420/r320 stable/9 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: attilio@FreeBSD.org List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Jul 2012 14:42:51 -0000 On Fri, Jul 27, 2012 at 3:33 PM, Andrew Boyer wro= te: > > On Jul 26, 2012, at 8:50 PM, Sean Bruno wrote: > >> For the time being I had to revert the following from my stable/9 tree. >> Otherwise I would get a kernel panic on shutdown from ipmi(4). >> >> http://svnweb.freebsd.org/base?view=3Drevision&revision=3D237839 >> http://svnweb.freebsd.org/base?view=3Drevision&revision=3D221121 >> > > > On a somewhat related note: We noticed recently that you can't pet or dis= able the IPMI hardware watchdog once SCHEDULER_STOPPED() is true. This mea= ns it can fire unexpectedly while you're dumping core or rebooting, dependi= ng on how long the timeout was on the pet before the panic. The ipmi drive= r will need to process the command differently if the scheduler is stopped.= I haven't had time to look at a fix yet. I recall I fixed that internally for SV, but the key here is that we need to find an unified (or a default policy). More specifically, do we want the watchdog also covers the kernel dump part (because of possible deadlocks when dumping). If the answer is yes, we likely need pat the watchdog from within the dumping cycle itself. If the answer is no, then we can just disable it when entering the panic path. But anyway, we need to identify a default policy that makes sense first. Attilio --=20 Peace can only be achieved by understanding - A. Einstein