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 S1752716AbdAZOYC (ORCPT <rfc822;w@1wt.eu>);
        Thu, 26 Jan 2017 09:24:02 -0500
Received: from mx1.redhat.com ([209.132.183.28]:42918 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752030AbdAZOYB (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 26 Jan 2017 09:24:01 -0500
Message-ID: <1485440636.15964.47.camel@redhat.com>
Subject: Re: [PATCH 1/7] x86/fpu: Simplify the fpu->last_cpu logic and
 rename it to fpu->fpregs_cached
From: Rik van Riel <riel@redhat.com>
To: Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>, "H . Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Yu-cheng Yu <yu-cheng.yu@intel.com>
Date: Thu, 26 Jan 2017 09:23:56 -0500
In-Reply-To: <1485429989-23340-2-git-send-email-mingo@kernel.org>
References: <1485429989-23340-1-git-send-email-mingo@kernel.org>
         <1485429989-23340-2-git-send-email-mingo@kernel.org>
Organization: Red Hat, Inc
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 26 Jan 2017 14:24:01 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 2017-01-26 at 12:26 +0100, Ingo Molnar wrote:
> 
> @@ -322,6 +308,16 @@ struct fpu {
>  	unsigned char			fpregs_active;
>  
>  	/*
> +	 * @fpregs_cached:
> +	 *
> +	 * This flag tells us whether this context is loaded into a
> CPU
> +	 * right now.

Not quite. You are still checking against fpu_fpregs_owner_ctx.

How about something like

      * This flag tells us whether this context was loaded into
      * its current CPU; fpu_fpregs_owner_ctx will tell us whether
      * this context is actually in the registers.

> +	 *
> +	 * This is set to 0 if a task is migrated to another CPU.
> +	 */
> +	unsigned char			fpregs_cached;
> +
> +	/*
>  	 * @state:
>  	 *
>  	 * In-memory copy of all FPU registers that we save/restore