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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D3AF3C433F5 for ; Mon, 16 May 2022 21:41:10 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4L2CP10G0zz3cHn for ; Tue, 17 May 2022 07:41:09 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=UAEfoymf; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.com (client-ip=195.135.220.28; helo=smtp-out1.suse.de; envelope-from=pmladek@suse.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=UAEfoymf; dkim-atps=neutral Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4L21CJ6zjLz3bvl for ; Tue, 17 May 2022 00:02:03 +1000 (AEST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 2362F21F5C; Mon, 16 May 2022 14:02:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1652709720; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6xX/Xo1YcyoxhDGVtD+3aF7M9NKMVvtDcsL11SFSAQU=; b=UAEfoymfYf+QAbCzE3oYFS/LnW9rFBs924Unv93LKXY9GoxfXpJbDSZbNYQc1AwPujLxjA jmh7TvIJcQUwFXF0iE9L66PiKtfkKtU88t+hUCpM3m0czPO3TM37NQr+8KouKC5lf5Okex k2McswvfGUIvb+tozWKmApBRPL9ucl0= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id D43112C141; Mon, 16 May 2022 14:01:57 +0000 (UTC) Date: Mon, 16 May 2022 16:01:57 +0200 From: Petr Mladek To: "Guilherme G. Piccoli" Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Message-ID: References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220427224924.592546-20-gpiccoli@igalia.com> X-Mailman-Approved-At: Tue, 17 May 2022 07:40:39 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , Justin Chen , Pavel Machek , Alexander Gordeev , "K. Y. Srinivasan" , Wei Liu , stern@rowland.harvard.edu, xen-devel@lists.xenproject.org, Christian Borntraeger , linux-pm@vger.kernel.org, linux-um@lists.infradead.org, Nicholas Piggin , luto@kernel.org, Mihai Carabas , tglx@linutronix.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, senozhatsky@chromium.org, d.hatayama@jp.fujitsu.com, mhiramat@kernel.org, akpm@linux-foundation.org, linux-hyperv@vger.kernel.org, dave.hansen@linux.intel.com, linux-s390@vger.kernel.org, Stephen Hemminger , Vasily Gorbik , vgoyal@redhat.com, Sven Schnelle , Andrea Parri , linux-xtensa@linux-xtensa.org, john.ogness@linutronix.de, Scott Branden , coresight@lists.linaro.org, Florian Fainelli , Markus Mayer , hidehiro.kawai.ez@hitachi.com, linux-arm-kernel@lists.infradead.org, kernel-dev@igalia.com, fabiomirmar@gmail.com, halves@canonical.com, alejandro.j.jimenez@oracle.com, feng.tang@intel.com, zhenwei pi , will@kernel.org, Doug Berger , bhe@redhat.com, corbet@lwn.net, Dexuan Cui , Evan Green , bcm-kernel-feedback-list@broadcom.com, Tianyu Lan , keescook@chromium.org, arnd@arndb.de, Haiyang Zhang , rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, openipmi-developer@lists.sourceforge.net, Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Sebastian Reichel , linux-alpha@vger.kernel.org, Brian Norris , "David S. Miller" , peterz@infradead.org, linux-remoteproc@vger.kernel.org, mikelley@microsoft.com, sparclinux@vger.kernel.org, Lee Jones , Ard Biesheuvel , linux-leds@vger.kernel.org, x86@kernel.org, mingo@redhat.com, dyoung@redhat.com, paulmck@kernel.org, Heiko Carstens , Shile Zhang , Wang ShaoBo , Christophe JAILLET , David Gow , linux-tegra@vger.kernel.org, andriy.shevchenko@linux.intel.com, Hari Bathini , linux-edac@vger.kernel.org, jgross@suse.com, netdev@vger.kernel.org, kernel@gpiccoli.net, kexec@lists.infradead.org, linux-mips@vger.kernel.org, Julius Werner , vkuznets@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed 2022-04-27 19:49:13, Guilherme G. Piccoli wrote: > The goal of this new panic notifier is to allow its users to register > callbacks to run very early in the panic path. This aims hypervisor/FW > notification mechanisms as well as simple LED functions, and any other > simple and safe mechanism that should run early in the panic path; more > dangerous callbacks should execute later. > > For now, the patch is almost a no-op (although it changes a bit the > ordering in which some panic notifiers are executed). In a subsequent > patch, the panic path will be refactored, then the panic hypervisor > notifiers will effectively run very early in the panic path. > > We also defer documenting it all properly in the subsequent refactor > patch. While at it, we removed some useless header inclusions and > fixed some notifiers return too (by using the standard NOTIFY_DONE). > --- a/arch/mips/sgi-ip22/ip22-reset.c > +++ b/arch/mips/sgi-ip22/ip22-reset.c > @@ -195,7 +195,7 @@ static int __init reboot_setup(void) > } > > timer_setup(&blink_timer, blink_timeout, 0); > - atomic_notifier_chain_register(&panic_notifier_list, &panic_block); > + atomic_notifier_chain_register(&panic_hypervisor_list, &panic_block); This notifier enables blinking. It is not much safe. It calls mod_timer() that takes a lock internally. This kind of functionality should go into the last list called before panic() enters the infinite loop. IMHO, all the blinking stuff should go there. > > return 0; > } > diff --git a/arch/mips/sgi-ip32/ip32-reset.c b/arch/mips/sgi-ip32/ip32-reset.c > index 18d1c115cd53..9ee1302c9d13 100644 > --- a/arch/mips/sgi-ip32/ip32-reset.c > +++ b/arch/mips/sgi-ip32/ip32-reset.c > @@ -145,7 +144,7 @@ static __init int ip32_reboot_setup(void) > pm_power_off = ip32_machine_halt; > > timer_setup(&blink_timer, blink_timeout, 0); > - atomic_notifier_chain_register(&panic_notifier_list, &panic_block); > + atomic_notifier_chain_register(&panic_hypervisor_list, &panic_block); Same here. Should be done only before the "loop". > > return 0; > } > --- a/drivers/firmware/google/gsmi.c > +++ b/drivers/firmware/google/gsmi.c > @@ -1034,7 +1034,7 @@ static __init int gsmi_init(void) > > register_reboot_notifier(&gsmi_reboot_notifier); > register_die_notifier(&gsmi_die_notifier); > - atomic_notifier_chain_register(&panic_notifier_list, > + atomic_notifier_chain_register(&panic_hypervisor_list, > &gsmi_panic_notifier); I am not sure about this one. It looks like some logging or pre_reboot stuff. > > printk(KERN_INFO "gsmi version " DRIVER_VERSION " loaded\n"); > --- a/drivers/leds/trigger/ledtrig-activity.c > +++ b/drivers/leds/trigger/ledtrig-activity.c > @@ -247,7 +247,7 @@ static int __init activity_init(void) > int rc = led_trigger_register(&activity_led_trigger); > > if (!rc) { > - atomic_notifier_chain_register(&panic_notifier_list, > + atomic_notifier_chain_register(&panic_hypervisor_list, > &activity_panic_nb); The notifier is trivial. It just sets a variable. But still, it is about blinking and should be done in the last "loop" list. > register_reboot_notifier(&activity_reboot_nb); > } > --- a/drivers/leds/trigger/ledtrig-heartbeat.c > +++ b/drivers/leds/trigger/ledtrig-heartbeat.c > @@ -190,7 +190,7 @@ static int __init heartbeat_trig_init(void) > int rc = led_trigger_register(&heartbeat_led_trigger); > > if (!rc) { > - atomic_notifier_chain_register(&panic_notifier_list, > + atomic_notifier_chain_register(&panic_hypervisor_list, > &heartbeat_panic_nb); Same here. Blinking => loop list. > register_reboot_notifier(&heartbeat_reboot_nb); > } > diff --git a/drivers/misc/bcm-vk/bcm_vk_dev.c b/drivers/misc/bcm-vk/bcm_vk_dev.c > index a16b99bdaa13..d9d5199cdb2b 100644 > --- a/drivers/misc/bcm-vk/bcm_vk_dev.c > +++ b/drivers/misc/bcm-vk/bcm_vk_dev.c > @@ -1446,7 +1446,7 @@ static int bcm_vk_probe(struct pci_dev *pdev, const struct pci_device_id *ent) > > /* register for panic notifier */ > vk->panic_nb.notifier_call = bcm_vk_on_panic; > - err = atomic_notifier_chain_register(&panic_notifier_list, > + err = atomic_notifier_chain_register(&panic_hypervisor_list, > &vk->panic_nb); It seems to reset some hardware or so. IMHO, it should go into the pre-reboot list. > if (err) { > dev_err(dev, "Fail to register panic notifier\n"); > --- a/drivers/power/reset/ltc2952-poweroff.c > +++ b/drivers/power/reset/ltc2952-poweroff.c > @@ -279,7 +279,7 @@ static int ltc2952_poweroff_probe(struct platform_device *pdev) > pm_power_off = ltc2952_poweroff_kill; > > data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic; > - atomic_notifier_chain_register(&panic_notifier_list, > + atomic_notifier_chain_register(&panic_hypervisor_list, > &data->panic_notifier); I looks like this somehow triggers the reboot. IMHO, it should go into the pre_reboot list. > dev_info(&pdev->dev, "probe successful\n"); > > --- a/drivers/soc/bcm/brcmstb/pm/pm-arm.c > +++ b/drivers/soc/bcm/brcmstb/pm/pm-arm.c > @@ -814,7 +814,7 @@ static int brcmstb_pm_probe(struct platform_device *pdev) > goto out; > } > > - atomic_notifier_chain_register(&panic_notifier_list, > + atomic_notifier_chain_register(&panic_hypervisor_list, > &brcmstb_pm_panic_nb); I am not sure about this one. It instruct some HW to preserve DRAM. IMHO, it better fits into pre_reboot category but I do not have strong opinion. > > pm_power_off = brcmstb_pm_poweroff; Best Regards, Petr