From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751384AbcCACzc (ORCPT ); Mon, 29 Feb 2016 21:55:32 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:33941 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750800AbcCACzb (ORCPT ); Mon, 29 Feb 2016 21:55:31 -0500 Subject: Re: [PATCH 3/3] hpwdt: Use nmi_panic() when kernel panics in NMI handler To: Hidehiro Kawai , Andrew Morton , Thomas Mingarelli , Wim Van Sebroeck , Corey Minyard References: <20160301015035.4318.78677.stgit@softrs> <20160301015041.4318.93922.stgit@softrs> Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Hocko , Borislav Petkov , openipmi-developer@lists.sourceforge.net From: Guenter Roeck Message-ID: <56D5049C.50207@roeck-us.net> Date: Mon, 29 Feb 2016 18:55:24 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160301015041.4318.93922.stgit@softrs> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/29/2016 05:50 PM, Hidehiro Kawai wrote: > commit 58c5661f2144 ("panic, x86: Allow CPUs to save registers even > if looping in NMI context") introduced nmi_panic() which prevents > concurrent/recursive execution of panic(). It also saves registers > for the crash dump on x86. > > hpwdt driver can call panic() from NMI handler, so replace it with > nmi_panic(). > > Signed-off-by: Hidehiro Kawai > Cc: Thomas Mingarelli > Cc: Wim Van Sebroeck > Cc: Guenter Roeck > Cc: linux-watchdog@vger.kernel.org > --- > drivers/watchdog/hpwdt.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c > index 92443c3..fd0486f 100644 > --- a/drivers/watchdog/hpwdt.c > +++ b/drivers/watchdog/hpwdt.c > @@ -496,11 +496,12 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs) > > if (!is_icru && !is_uefi) { > if (cmn_regs.u1.ral == 0) { > - panic("An NMI occurred, " > + nmi_panic(regs, "An NMI occurred, " > "but unable to determine source.\n"); This message should really be in a single line. Sure, strictly speaking that should be done in a separate patch, but since you touch the line you might as well fix it. > + goto handled; The goto is unnecessary. Just return NMI_HANDLED. > } > } > - panic("An NMI occurred. Depending on your system the reason " > + nmi_panic(regs, "An NMI occurred. Depending on your system the reason " > "for the NMI is logged in any one of the following " > "resources:\n" > "1. Integrated Management Log (IML)\n" > @@ -508,6 +509,13 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs) > "3. OA Forward Progress Log\n" > "4. iLO Event Log"); > > +handled: > + /* > + * Returning from nmi_panic() means this CPU was processing panic() > + * before NMI. Return NMI_HANDLED and go back to panic routines. > + */ I don't think this comment adds much if any value. > + return NMI_HANDLED; > + > out: Any goto to this label does no longer serve a useful purpose (if it ever served one), and should be replaced with "return NMI_DONE;" > return NMI_DONE; > } > > >