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From:   Thomas Gleixner <tglx@linutronix.de>
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To:     Sean Christopherson <seanjc@google.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org
Cc:     "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org,
        "Guilherme G . Piccoli" <gpiccoli@igalia.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCH] x86/nmi: Make register_nmi_handler() more robust
In-Reply-To: <87zgjlsn75.ffs@tglx>
References: <20220511234332.3654455-1-seanjc@google.com> <87zgjlsn75.ffs@tglx>
Date:   Sun, 15 May 2022 13:37:29 +0200
Message-ID: <87wnenqb5y.ffs@tglx>
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On Fri, May 13 2022 at 13:10, Thomas Gleixner wrote:
> @@ -157,7 +157,7 @@ int __register_nmi_handler(unsigned int
>  	struct nmi_desc *desc = nmi_to_desc(type);
>  	unsigned long flags;
>  
> -	if (!action->handler)
> +	if (WARN_ON_ONCE(action->handler || !list_empty(&action->list)))

Bah. That should obviously be !action->handler. Let me send V2