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 S1755800AbcDGLey (ORCPT <rfc822;w@1wt.eu>);
	Thu, 7 Apr 2016 07:34:54 -0400
Received: from foss.arm.com ([217.140.101.70]:33405 "EHLO foss.arm.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1755388AbcDGLex (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 7 Apr 2016 07:34:53 -0400
Date: Thu, 7 Apr 2016 12:34:48 +0100
From: Will Deacon <will.deacon@arm.com>
To: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-kernel@vger.kernel.org, rt@linutronix.de,
        Mark Rutland <mark.rutland@arm.com>,
        Russell King <linux@arm.linux.org.uk>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function
 call
Message-ID: <20160407113448.GF5657@arm.com>
References: <1459932030-43882-1-git-send-email-anna-maria@linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1459932030-43882-1-git-send-email-anna-maria@linutronix.de>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Apr 06, 2016 at 10:40:30AM +0200, Anna-Maria Gleixner wrote:
> Since commit 1cf4f629d9d2 ("cpu/hotplug: Move online calls to
> hotplugged cpu") it is ensured that callbacks of CPU_ONLINE and
> CPU_DOWN_PREPARE are processed on the hotplugged CPU. Due to this SMP
> function calls are no longer required.
> 
> Replace smp_call_function_single() with a direct call of
> reset_ctrl_regs(). To keep the calling convention, interrupts are
> explicitly disabled around the call.
> 
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
>  arch/arm/kernel/hw_breakpoint.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> --- a/arch/arm/kernel/hw_breakpoint.c
> +++ b/arch/arm/kernel/hw_breakpoint.c
> @@ -1023,8 +1023,11 @@ static void reset_ctrl_regs(void *unused
>  static int dbg_reset_notify(struct notifier_block *self,
>  				      unsigned long action, void *cpu)
>  {
> -	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
> -		smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
> +	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) {
> +		local_irq_disable();
> +		reset_ctrl_regs(NULL);
> +		local_irq_enable();
> +	}
>  
>  	return NOTIFY_OK;
>  }

Acked-by: Will Deacon <will.deacon@arm.com>

Will