Message-ID: <YoJgcC8c6LaKADZV@alley>
Date:   Mon, 16 May 2022 16:33:41 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     akpm@...ux-foundation.org, bhe@...hat.com,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com, coresight@...ts.linaro.org,
        linuxppc-dev@...ts.ozlabs.org, linux-alpha@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-edac@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org,
        netdev@...r.kernel.org, openipmi-developer@...ts.sourceforge.net,
        rcu@...r.kernel.org, sparclinux@...r.kernel.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        kernel-dev@...lia.com, kernel@...ccoli.net, halves@...onical.com,
        fabiomirmar@...il.com, alejandro.j.jimenez@...cle.com,
        andriy.shevchenko@...ux.intel.com, arnd@...db.de, bp@...en8.de,
        corbet@....net, d.hatayama@...fujitsu.com,
        dave.hansen@...ux.intel.com, dyoung@...hat.com,
        feng.tang@...el.com, gregkh@...uxfoundation.org,
        mikelley@...rosoft.com, hidehiro.kawai.ez@...achi.com,
        jgross@...e.com, john.ogness@...utronix.de, keescook@...omium.org,
        luto@...nel.org, mhiramat@...nel.org, mingo@...hat.com,
        paulmck@...nel.org, peterz@...radead.org, rostedt@...dmis.org,
        senozhatsky@...omium.org, stern@...land.harvard.edu,
        tglx@...utronix.de, vgoyal@...hat.com, vkuznets@...hat.com,
        will@...nel.org, Alex Elder <elder@...nel.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Chris Zankel <chris@...kel.net>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Corey Minyard <minyard@....org>,
        Dexuan Cui <decui@...rosoft.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Helge Deller <deller@....de>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        James Morse <james.morse@....com>,
        Johannes Berg <johannes@...solutions.net>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Matt Turner <mattst88@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Max Filippov <jcmvbkbc@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>, Pavel Machek <pavel@....cz>,
        Richard Weinberger <richard@....at>,
        Robert Richter <rric@...nel.org>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Tony Luck <tony.luck@...el.com>,
        Vasily Gorbik <gor@...ux.ibm.com>, Wei Liu <wei.liu@...nel.org>
Subject: Re: [PATCH 21/30] panic: Introduce the panic pre-reboot notifier list

On Wed 2022-04-27 19:49:15, Guilherme G. Piccoli wrote:
> This patch renames the panic_notifier_list to panic_pre_reboot_list;
> the idea is that a subsequent patch will refactor the panic path
> in order to better split the notifiers, running some of them very
> early, some of them not so early [but still before kmsg_dump()] and
> finally, the rest should execute late, after kdump. The latter ones
> are now in the panic pre-reboot list - the name comes from the idea
> that these notifiers execute before panic() attempts rebooting the
> machine (if that option is set).
> 
> We also took the opportunity to clean-up useless header inclusions,
> improve some notifier block declarations (e.g. in ibmasm/heartbeat.c)
> and more important, change some priorities - we hereby set 2 notifiers
> to run late in the list [iss_panic_event() and the IPMI panic_event()]
> due to the risks they offer (may not return, for example).
> Proper documentation is going to be provided in a subsequent patch,
> that effectively refactors the panic path.
> 
> --- a/drivers/edac/altera_edac.c
> +++ b/drivers/edac/altera_edac.c
> @@ -2163,7 +2162,7 @@ static int altr_edac_a10_probe(struct platform_device *pdev)
>  		int dberror, err_addr;
>  
>  		edac->panic_notifier.notifier_call = s10_edac_dberr_handler;
> -		atomic_notifier_chain_register(&panic_notifier_list,
> +		atomic_notifier_chain_register(&panic_pre_reboot_list,

My understanding is that this notifier first prints info about ECC
errors and then triggers reboot. It might make sense to split it
into two notifiers.


>  					       &edac->panic_notifier);
>  
>  		/* Printout a message if uncorrectable error previously. */
> --- a/drivers/leds/trigger/ledtrig-panic.c
> +++ b/drivers/leds/trigger/ledtrig-panic.c
> @@ -64,7 +63,7 @@ static long led_panic_blink(int state)
>  
>  static int __init ledtrig_panic_init(void)
>  {
> -	atomic_notifier_chain_register(&panic_notifier_list,
> +	atomic_notifier_chain_register(&panic_pre_reboot_list,
>  				       &led_trigger_panic_nb);

Blinking => should go to the last "post_reboot/loop" list.


>  
>  	led_trigger_register_simple("panic", &trigger);
> --- a/drivers/misc/ibmasm/heartbeat.c
> +++ b/drivers/misc/ibmasm/heartbeat.c
> @@ -32,20 +31,23 @@ static int suspend_heartbeats = 0;
>  static int panic_happened(struct notifier_block *n, unsigned long val, void *v)
>  {
>  	suspend_heartbeats = 1;
> -	return 0;
> +	return NOTIFY_DONE;
>  }
>  
> -static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
> +static struct notifier_block panic_notifier = {
> +	.notifier_call = panic_happened,
> +};
>  
>  void ibmasm_register_panic_notifier(void)
>  {
> -	atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
> +	atomic_notifier_chain_register(&panic_pre_reboot_list,
> +					&panic_notifier);

Same here. Blinking => should go to the last "post_reboot/loop" list.


>  }
>  
>  void ibmasm_unregister_panic_notifier(void)
>  {
> -	atomic_notifier_chain_unregister(&panic_notifier_list,
> -			&panic_notifier);
> +	atomic_notifier_chain_unregister(&panic_pre_reboot_list,
> +					&panic_notifier);
>  }


The rest of the moved notifiers seem to fit well this "pre_reboot"
list.

Best Regards,
Petr

Powered by blists - more mailing lists