linux-kernel - Re: [PATCH] x86/mce: fix a wrong assignment of i

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Date:   Thu, 11 Jun 2020 09:55:00 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Zhenzhong Duan <zhenzhong.duan@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        x86@...nel.org, bp@...en8.de, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, Yazen Ghannam <yazen.ghannam@....com>
Subject: Re: [PATCH] x86/mce: fix a wrong assignment of i_mce.status

+Yazen

On Thu, Jun 11, 2020 at 10:32:38AM +0800, Zhenzhong Duan wrote:
> The original code is a nop as i_mce.status is or'ed with part of itself,
> fix it.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...il.com>
> ---
>  arch/x86/kernel/cpu/mce/inject.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
> index 3413b41..dc28a61 100644
> --- a/arch/x86/kernel/cpu/mce/inject.c
> +++ b/arch/x86/kernel/cpu/mce/inject.c
> @@ -511,7 +511,7 @@ static void do_inject(void)
>  	 */
>  	if (inj_type == DFR_INT_INJ) {
>  		i_mce.status |= MCI_STATUS_DEFERRED;
> -		i_mce.status |= (i_mce.status & ~MCI_STATUS_UC);
> +		i_mce.status &= ~MCI_STATUS_UC;

Boris: "git blame" says you wrote this code. Patch looks right (in
that it makes the code do what the comment just above says it is trying
to do):

         * - MCx_STATUS[UC] cleared: deferred errors are _not_ UC

But this is AMD specific, so I'll defer judgement

-Tony