linux-kernel - Re: [PATCH 2/2] x86 mce: use new printk recursion disabling interface

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Date:	Fri, 25 May 2012 09:41:14 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	ShuoX Liu <shuox.liu@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yanmin Zhang <yanmin_zhang@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>, andi@...stfloor.org,
	Tony Luck <tony.luck@...el.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 2/2] x86 mce: use new printk recursion disabling interface

On Fri, May 25, 2012 at 03:21:12PM +0800, ShuoX Liu wrote:
> From: ShuoX Liu <shuox.liu@...el.com>
> 
> Disable printk recursion to make sure MCE logs printed out.
> 
> Signed-off-by: Yanmin Zhang <yanmin_zhang@...ux.intel.com>
> Signed-off-by: ShuoX Liu <shuox.liu@...el.com>
> ---
>  arch/x86/kernel/cpu/mcheck/mce.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> index 2afcbd2..365c35d 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -1015,6 +1015,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
>  	DECLARE_BITMAP(toclear, MAX_NR_BANKS);
>  	char *msg = "Unknown";
>  
> +	printk_recursion_check_disable();
>  	atomic_inc(&mce_entry);
>  
>  	this_cpu_inc(mce_exception_count);
> @@ -1144,6 +1145,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
>  	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
>  out:
>  	atomic_dec(&mce_entry);
> +	printk_recursion_check_enable();

Looks like those should be at the beginning and the end of print_mce() -
do_machine_check() could exit without printing an MCE and disabling the
recursion check then is superfluous, methinks.

Thanks.

-- 
Regards/Gruss,
    Boris.
--
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