linux-kernel - Re: [PATCH] x86, microcode: unregister syscore

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Message-Id: <201103302304.24116.rjw@sisk.pl>
Date:	Wed, 30 Mar 2011 23:04:23 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Xiaotian Feng <dfeng@...hat.com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86, microcode: unregister syscore_ops after microcode unloaded

On Tuesday, March 29, 2011, Xiaotian Feng wrote:
> Currently, microcode doesn't unregister syscore_ops after it's unloaded.
> So if we modprobe then rmmod microcode, the stale microcode syscore_ops info
> will stay on syscore_ops_list. Later when we're trying to reboot/halt/shutdown
> the machine, kernel will panic on syscore_shutdown(). With the patch
> applied, I can reboot/halt/shutdown my machine successfully.
> 
> Signed-off-by: Xiaotian Feng <dfeng@...hat.com>
> Cc: Tigran Aivazian <tigran@...azian.fsnet.co.uk> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>

Acked-by: Rafael J. Wysocki <rjw@...k.pl>

> ---
>  arch/x86/kernel/microcode_core.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
> index 5ed0ab5..f924280 100644
> --- a/arch/x86/kernel/microcode_core.c
> +++ b/arch/x86/kernel/microcode_core.c
> @@ -550,6 +550,7 @@ static void __exit microcode_exit(void)
>  	microcode_dev_exit();
>  
>  	unregister_hotcpu_notifier(&mc_cpu_notifier);
> +	unregister_syscore_ops(&mc_syscore_ops);
>  
>  	get_online_cpus();
>  	mutex_lock(&microcode_mutex);
> 

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