From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751935AbcEJKeO (ORCPT <rfc822;w@1wt.eu>);
	Tue, 10 May 2016 06:34:14 -0400
Received: from foss.arm.com ([217.140.101.70]:43785 "EHLO foss.arm.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751004AbcEJKeL (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 10 May 2016 06:34:11 -0400
Date: Tue, 10 May 2016 11:34:01 +0100
From: Mark Rutland <mark.rutland@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Will Deacon <will.deacon@arm.com>, Dennis Chen <dennis.chen@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH] arm64: secondary_start_kernel: Remove unnecessary barrier
Message-ID: <20160510103400.GG687@leverpostej>
References: <1462875281-5063-1-git-send-email-suzuki.poulose@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1462875281-5063-1-git-send-email-suzuki.poulose@arm.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, May 10, 2016 at 11:14:41AM +0100, Suzuki K Poulose wrote:
> Remove the unnecessary smp_wmb(), which was added to make sure
> that the update_cpu_boot_status() completes before we mark the
> CPU online. But update_cpu_boot_status() already has dsb() (required
> for the failing CPUs) to ensure the correct behavior.
> 
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Dennis Chen <dennis.chen@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
>  arch/arm64/kernel/smp.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index b2d5f4e..ec040a8 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -225,8 +225,6 @@ asmlinkage void secondary_start_kernel(void)
>  	pr_info("CPU%u: Booted secondary processor [%08x]\n",
>  					 cpu, read_cpuid_id());
>  	update_cpu_boot_status(CPU_BOOT_SUCCESS);
> -	/* Make sure the status update is visible before we complete */
> -	smp_wmb();
>  	set_cpu_online(cpu, true);
>  	complete(&cpu_running);
>  
> -- 
> 1.7.9.5
>