linux-kernel - Re: [patch v2 04/10] kdump: Trigger kdump via panic notifier chain on s390

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Date:	Mon, 1 Aug 2011 16:41:14 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Cc:	ebiederm@...ssion.com, mahesh@...ux.vnet.ibm.com, hbabu@...ibm.com,
	oomichi@....nes.nec.co.jp, horms@...ge.net.au,
	schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org
Subject: Re: [patch v2 04/10] kdump: Trigger kdump via panic notifier chain
 on s390

On Wed, Jul 27, 2011 at 02:55:08PM +0200, Michael Holzheu wrote:
> From: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
> 
> On s390 we have the possibility to configure actions that are executed in
> case of a kernel panic. E.g. it is possible to automatically trigger an s390
> stand-alone dump. The actions are called via a panic notifier.  We also want
> to trigger kdump via the notifier call chain. Therefore this patch disables
> for s390 the direct kdump invocation in the panic() function.

Doesn't this reduce the reliability of the operation as you are assuming
that panic notifier list is fine and not corrupted.

There might be other generic notifiers registerd on panic notifier list
too. So in your case, are there multiple subsystem registering for panic
notifiers? If not, why not call crash_kexec() directly. Are there any
other actions you want to take on panic then calling crash_kexec()?

Thanks
Vivek

> 
> Signed-off-by: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
> ---
>  kernel/panic.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -84,9 +84,12 @@ NORET_TYPE void panic(const char * fmt,
>  	/*
>  	 * If we have crashed and we have a crash kernel loaded let it handle
>  	 * everything else.
> +	 * For s390 kdump is triggered via the panic notifier call chain.
>  	 * Do we want to call this before we try to display a message?
>  	 */
> +#if !defined(CONFIG_S390)
>  	crash_kexec(NULL);
> +#endif
>  
>  	kmsg_dump(KMSG_DUMP_PANIC);
>  
--
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