linux-kernel - Re: [v3 PATCH 2/4] powernv:smp: Add busy-wait loop as fall back for CPU-Hotplug

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Date:   Mon, 27 Mar 2017 22:43:44 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Michael Neuling <mikey@...ling.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Anton Blanchard <anton@...ba.org>,
        Balbir Singh <bsingharora@...il.com>,
        Akshay Adiga <akshay.adiga@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
Subject: Re: [v3 PATCH 2/4] powernv:smp: Add busy-wait loop as fall back for CPU-Hotplug

"Gautham R. Shenoy" <ego@...ux.vnet.ibm.com> writes:

> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 419edff..f335e0f 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -283,8 +283,16 @@ unsigned long pnv_cpu_offline(unsigned int cpu)
>  	} else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
>  		   (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
>  		srr1 = power7_sleep();
> -	} else {
> +	} else if (idle_states & OPAL_PM_NAP_ENABLED) {
>  		srr1 = power7_nap(1);
> +	} else {
> +		/* This is the fallback method. We emulate snooze */
> +		while (!generic_check_cpu_restart(cpu)) {

Breaks the SMP=n build :/

arch/powerpc/platforms/powernv/idle.c:299:11: error: implicit declaration of function 'generic_check_cpu_restart' [-Werror=implicit-function-declaration]

cheers