From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EF5CC001DC for ; Thu, 15 Jun 2023 13:21:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343926AbjFONVQ (ORCPT ); Thu, 15 Jun 2023 09:21:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240465AbjFONVO (ORCPT ); Thu, 15 Jun 2023 09:21:14 -0400 Received: from mail11.truemail.it (mail11.truemail.it [IPv6:2001:4b7e:0:8::81]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0583270D; Thu, 15 Jun 2023 06:21:10 -0700 (PDT) Received: from francesco-nb.int.toradex.com (31-10-206-125.static.upc.ch [31.10.206.125]) by mail11.truemail.it (Postfix) with ESMTPA id 82320206E1; Thu, 15 Jun 2023 15:21:08 +0200 (CEST) Date: Thu, 15 Jun 2023 15:21:02 +0200 From: Francesco Dolcini To: Nishanth Menon Cc: Benjamin Bara , Wolfram Sang , Lee Jones , rafael.j.wysocki@intel.com, dmitry.osipenko@collabora.com, peterz@infradead.org, jonathanh@nvidia.com, richard.leitner@linux.dev, treding@nvidia.com, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org, Benjamin Bara , stable@vger.kernel.org Subject: Re: [PATCH v6 1/5] kernel/reboot: emergency_restart: set correct system_state Message-ID: References: <20230327-tegra-pmic-reboot-v6-0-af44a4cd82e9@skidata.com> <20230327-tegra-pmic-reboot-v6-1-af44a4cd82e9@skidata.com> <20230615000650.coyphnwdai7smww7@unblended> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230615000650.coyphnwdai7smww7@unblended> Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Hello Nishanth, On Wed, Jun 14, 2023 at 07:06:50PM -0500, Nishanth Menon wrote: > On 21:02-20230509, Benjamin Bara wrote: > > From: Benjamin Bara > > > > As the emergency restart does not call kernel_restart_prepare(), the > > system_state stays in SYSTEM_RUNNING. > > > > Since bae1d3a05a8b, this hinders i2c_in_atomic_xfer_mode() from becoming > > active, and therefore might lead to avoidable warnings in the restart > > handlers, e.g.: > > > > [ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0 > > [ 12.676926] Voluntary context switch within RCU read-side critical section! > > ... > > [ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114 > > [ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70 > > ... > > [ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58 > > [ 13.001050] machine_restart from panic+0x2a8/0x32c > > > > Avoid these by setting the correct system_state. > > > > Fixes: bae1d3a05a8b ("i2c: core: remove use of in_atomic()") > > Cc: stable@vger.kernel.org # v5.2+ > > Signed-off-by: Benjamin Bara > > --- > > kernel/reboot.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/kernel/reboot.c b/kernel/reboot.c > > index 3bba88c7ffc6..6ebef11c8876 100644 > > --- a/kernel/reboot.c > > +++ b/kernel/reboot.c > > @@ -74,6 +74,7 @@ void __weak (*pm_power_off)(void); > > void emergency_restart(void) > > { > > kmsg_dump(KMSG_DUMP_EMERG); > > + system_state = SYSTEM_RESTART; > > machine_emergency_restart(); > > } > > EXPORT_SYMBOL_GPL(emergency_restart); > > > > -- > > 2.34.1 > > > > Tested-by: Nishanth Menon > > This in addition to a deeper bug in our driver seems to have helped > resolve a report we had been looking at. Tested on beagleplay platform > > https://lore.kernel.org/all/ZGeHMjlnob2GFyHF@francesco-nb.int.toradex.com/ Is this patch going to fix the RCU warning I reported on that email or it is just part of a more complex solution? Francesco