linux-kernel - Re: [Patch v7 09/18] x86/smt: Convert cpu_smt_control check to cpu_smt

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Date:   Wed, 21 Nov 2018 14:38:49 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Tim Chen <tim.c.chen@...ux.intel.com>
cc:     Jiri Kosina <jikos@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Casey Schaufler <casey.schaufler@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Jon Masters <jcm@...hat.com>,
        Waiman Long <longman9394@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Stewart <david.c.stewart@...el.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        stable@...r.kernel.org
Subject: Re: [Patch v7 09/18] x86/smt: Convert cpu_smt_control check to
 cpu_smt_enabled static key

On Tue, 20 Nov 2018, Tim Chen wrote:
>  #if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
> -extern enum cpuhp_smt_control cpu_smt_control;
> +DECLARE_STATIC_KEY_TRUE(cpu_smt_enabled);
> +#define cpu_use_smt_and_hotplug	(static_branch_likely(&cpu_smt_enabled))

Errm. No. This looks like a variable and I really got confused by the code
change. What's wrong with inline functions?

Nothing, really. And no, you don't need that thing in the context switch
code at all.

Thanks,

	tglx