From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Mladek Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Date: Mon, 16 May 2022 16:01:57 +0200 Message-ID: References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> Mime-Version: 1.0 Return-path: 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= Content-Disposition: inline In-Reply-To: <20220427224924.592546-20-gpiccoli-wEGTBA9jqPzQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Guilherme G. Piccoli" Cc: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, coresight-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-alpha-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-edac-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-hyperv-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-leds-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mips-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-parisc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-remoteproc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-um-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-xtensa-PjhNF2WwrV/0Sa2dR60CXw@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, openipmi-developer-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, rcu-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sparclinux-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, kernel-dev-wEGTBA9jqPzQT0dZR+AlfA@public.gmane.org, kernel-WeLdAqEWwDvk1uMJSBkQmQ@public.gmane.org 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