From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CEE5E20B1E4 for ; Wed, 5 Mar 2025 10:42:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741171373; cv=none; b=gm1is1vXy3HM7gqu3uNIsCNOzq3dJllRGMWioCYtVba9omddazpHqecjuHk/lKUp36jFAN2ZbpMr7Doc6taOO0ezNzblXVLeDjCSnhrJnPt7XClEv5g77IlOVhly8mPBXUTrs7WCX/PZdH4Xnlo60yORTD4HyzSi+nTSpo9pIQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741171373; c=relaxed/simple; bh=q+P1kxlxk9nhHGxz1YAHbBytE232Dzrq0K9V62hixoA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VDFVryQo2TByiIR2k62wJfU+I1eGNvfN2aba1ytw7nAfleycdh8SNVlyyDkEzzhNjdFisnNqEljsWEkyco1PUOJ+cJTxEKTdxZzhPA24dbE7EdrijnvpvIvD9ugEO37bgdTaeRSMkcnawAEjRFt0maReHiUZBTxG50aSwdRxm2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1tpmCM-00054k-Ob; Wed, 05 Mar 2025 11:41:58 +0100 Message-ID: <43fb0965-04b7-41dc-ae3f-54676eefdbb5@pengutronix.de> Date: Wed, 5 Mar 2025 11:41:49 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/2] Add stop_on_panic support for watchdog To: George Cherian , linux@roeck-us.net, wim@linux-watchdog.org, jwerner@chromium.org, evanbenn@chromium.org, kabel@kernel.org, krzk@kernel.org, mazziesaccount@gmail.com, thomas.richard@bootlin.com, lma@chromium.org, bleung@chromium.org, support.opensource@diasemi.com, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, andy@kernel.org, paul@crapouillou.net, alexander.usyskin@intel.com, andreas.werner@men.de, daniel@thingy.jp, romain.perier@gmail.com, avifishman70@gmail.com, tmaimon77@gmail.com, tali.perry1@gmail.com, venture@google.com, yuenn@google.com, benjaminfair@google.com, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, naveen@kernel.org, mwalle@kernel.org, xingyu.wu@starfivetech.com, ziv.xu@starfivetech.com, hayashi.kunihiko@socionext.com, mhiramat@kernel.org Cc: chrome-platform@lists.linux.dev, linux-watchdog@vger.kernel.org, imx@lists.linux.dev, patches@opensource.cirrus.com, openbmc@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org References: <20250305101025.2279951-1-george.cherian@marvell.com> Content-Language: en-US From: Ahmad Fatoum In-Reply-To: <20250305101025.2279951-1-george.cherian@marvell.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2a0a:edc0:0:900:1d::77 X-SA-Exim-Mail-From: a.fatoum@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Hi George, On 05.03.25 11:10, George Cherian wrote: > This series adds a new kernel command line option to watchdog core to > stop the watchdog on panic. This is useul in certain systems which prevents > successful loading of kdump kernel due to watchdog reset. > > Some of the watchdog drivers stop function could sleep. For such > drivers the stop_on_panic is not valid as the notifier callback happens > in atomic context. Introduce WDIOF_STOP_MAYSLEEP flag to watchdog_info > options to indicate whether the stop function would sleep. Did you consider having a reset_on_panic instead, which sets a user-specified timeout on panic? This would make the mechanism useful also for watchdogs that can't be disabled and would protect against system lock up: Consider a memory-corruption bug (perhaps externally via DMA), which partially overwrites both main and kdump kernel. With a disabled watchdog, the system may not be able to recover on its own. If you did consider it, what made you decide against it? Thanks, Ahmad > > > Changelog: > v1 -> v2 > - Remove the per driver flag setting option > - Take the parameter via kernel command-line parameter to watchdog_core. > > v2 -> v3 > - Remove the helper function watchdog_stop_on_panic() from watchdog.h. > - There are no users for this. > > v3 -> v4 > - Since the panic notifier is in atomic context, watchdog functions > which sleep can't be called. > - Add an options flag WDIOF_STOP_MAYSLEEP to indicate whether stop > function sleeps. > - Simplify the stop_on_panic kernel command line parsing. > - Enable the panic notiffier only if the watchdog stop function doesn't > sleep > > George Cherian (2): > watchdog: Add a new flag WDIOF_STOP_MAYSLEEP > drivers: watchdog: Add support for panic notifier callback > > drivers/watchdog/advantech_ec_wdt.c | 3 ++- > drivers/watchdog/arm_smc_wdt.c | 3 ++- > drivers/watchdog/armada_37xx_wdt.c | 2 +- > drivers/watchdog/asm9260_wdt.c | 2 +- > drivers/watchdog/bcm47xx_wdt.c | 3 ++- > drivers/watchdog/bd9576_wdt.c | 2 +- > drivers/watchdog/bd96801_wdt.c | 2 +- > drivers/watchdog/cgbc_wdt.c | 2 +- > drivers/watchdog/cros_ec_wdt.c | 5 ++++- > drivers/watchdog/da9052_wdt.c | 3 ++- > drivers/watchdog/da9055_wdt.c | 4 +++- > drivers/watchdog/da9062_wdt.c | 4 +++- > drivers/watchdog/da9063_wdt.c | 4 +++- > drivers/watchdog/db8500_wdt.c | 5 ++++- > drivers/watchdog/dw_wdt.c | 5 +++-- > drivers/watchdog/f71808e_wdt.c | 3 ++- > drivers/watchdog/gpio_wdt.c | 2 +- > drivers/watchdog/i6300esb.c | 5 ++++- > drivers/watchdog/imx_sc_wdt.c | 2 +- > drivers/watchdog/intel-mid_wdt.c | 5 ++++- > drivers/watchdog/it87_wdt.c | 5 ++++- > drivers/watchdog/jz4740_wdt.c | 5 ++++- > drivers/watchdog/kempld_wdt.c | 3 ++- > drivers/watchdog/lenovo_se10_wdt.c | 5 ++++- > drivers/watchdog/max77620_wdt.c | 5 ++++- > drivers/watchdog/mei_wdt.c | 3 ++- > drivers/watchdog/menf21bmc_wdt.c | 4 +++- > drivers/watchdog/mlx_wdt.c | 2 +- > drivers/watchdog/msc313e_wdt.c | 5 ++++- > drivers/watchdog/npcm_wdt.c | 3 ++- > drivers/watchdog/omap_wdt.c | 5 ++++- > drivers/watchdog/pm8916_wdt.c | 5 +++-- > drivers/watchdog/pseries-wdt.c | 2 +- > drivers/watchdog/rave-sp-wdt.c | 5 ++++- > drivers/watchdog/renesas_wdt.c | 7 ++++-- > drivers/watchdog/retu_wdt.c | 5 ++++- > drivers/watchdog/rn5t618_wdt.c | 6 +++-- > drivers/watchdog/rzg2l_wdt.c | 5 ++++- > drivers/watchdog/rzv2h_wdt.c | 5 ++++- > drivers/watchdog/shwdt.c | 6 +++-- > drivers/watchdog/sl28cpld_wdt.c | 5 ++++- > drivers/watchdog/softdog.c | 5 ++++- > drivers/watchdog/sp805_wdt.c | 5 ++++- > drivers/watchdog/starfive-wdt.c | 3 ++- > drivers/watchdog/stpmic1_wdt.c | 5 ++++- > drivers/watchdog/ts4800_wdt.c | 5 ++++- > drivers/watchdog/twl4030_wdt.c | 5 ++++- > drivers/watchdog/uniphier_wdt.c | 3 ++- > drivers/watchdog/w83627hf_wdt.c | 5 ++++- > drivers/watchdog/watchdog_core.c | 35 +++++++++++++++++++++++++++++ > drivers/watchdog/wm831x_wdt.c | 5 ++++- > drivers/watchdog/wm8350_wdt.c | 5 ++++- > drivers/watchdog/xen_wdt.c | 5 ++++- > drivers/watchdog/ziirave_wdt.c | 5 ++++- > include/linux/watchdog.h | 2 ++ > include/uapi/linux/watchdog.h | 1 + > 56 files changed, 198 insertions(+), 58 deletions(-) > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |