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Date:   Sat, 3 Jun 2023 20:19:22 -0700
From:   Ashok Raj <ashok.raj@intel.com>
To:     Thomas Gleixner <tglx@linutronix.de>
CC:     LKML <linux-kernel@vger.kernel.org>, <x86@kernel.org>,
        Ashok Raj <ashok.raj@linux.intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Tony Luck" <tony.luck@intel.com>,
        Arjan van de Veen <arjan@linux.intel.com>,
        "Peter Zijlstra" <peterz@infradead.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Ashok Raj <ashok.raj@intel.com>
Subject: Re: [patch 4/6] x86/smp: Cure kexec() vs. mwait_play_dead() breakage
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References: <20230603193439.502645149@linutronix.de>
 <20230603200459.832650526@linutronix.de>
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On Sat, Jun 03, 2023 at 10:07:01PM +0200, Thomas Gleixner wrote:

[snip]

> Fixes: ea53069231f9 ("x86, hotplug: Use mwait to offline a processor, fix the legacy case")
> Reported-by: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/include/asm/smp.h |    2 +
>  arch/x86/kernel/smp.c      |   21 +++++++---------
>  arch/x86/kernel/smpboot.c  |   59 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 71 insertions(+), 11 deletions(-)
> 
> --- a/arch/x86/include/asm/smp.h
> +++ b/arch/x86/include/asm/smp.h
> @@ -132,6 +132,8 @@ void wbinvd_on_cpu(int cpu);
>  int wbinvd_on_all_cpus(void);
>  void cond_wakeup_cpu0(void);
>  
> +void smp_kick_mwait_play_dead(void);
> +

This seems like its missing prototype for #else for !CONFIG_SMP

 #else /* !CONFIG_SMP */
+#define smp_kick_mwait_play_dead(void) { }

Sorry I missed noticing this