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 S1758744AbcIHU1y (ORCPT <rfc822;w@1wt.eu>);
        Thu, 8 Sep 2016 16:27:54 -0400
Received: from Galois.linutronix.de ([146.0.238.70]:45888 "EHLO
        Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753787AbcIHU1w (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 8 Sep 2016 16:27:52 -0400
Date: Thu, 8 Sep 2016 22:25:06 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Fenghua Yu <fenghua.yu@intel.com>
cc: "H. Peter Anvin" <h.peter.anvin@intel.com>,
        Ingo Molnar <mingo@elte.hu>, Tony Luck <tony.luck@intel.com>,
        Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
        Borislav Petkov <bp@suse.de>, Stephane Eranian <eranian@google.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        David Carrillo-Cisneros <davidcc@google.com>, Shaohua Li <shli@fb.com>,
        Ravi V Shankar <ravi.v.shankar@intel.com>,
        Vikas Shivappa <vikas.shivappa@linux.intel.com>,
        Sai Prakhya <sai.praneeth.prakhya@intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [PATCH v2 28/33] x86/intel_rdt_rdtgroup.c: Read and write cpus
In-Reply-To: <1473328647-33116-29-git-send-email-fenghua.yu@intel.com>
Message-ID: <alpine.DEB.2.20.1609082212440.5454@nanos>
References: <1473328647-33116-1-git-send-email-fenghua.yu@intel.com> <1473328647-33116-29-git-send-email-fenghua.yu@intel.com>
User-Agent: Alpine 2.20 (DEB 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 8 Sep 2016, Fenghua Yu wrote:

> Normally each task is associated with one rdtgroup and we use the schema
> for that rdtgroup whenever the task is running. The user can designate
> some cpus to always use the same schema, regardless of which task is
> running. To do that the user write a cpumask bit string to the "cpus"
> file.

Is that just a left over of the previous series or am I completely confused
by now?

> +static int cpus_validate(struct cpumask *cpumask, struct rdtgroup *rdtgrp)
> +{
> +	int old_cpumask_bit, new_cpumask_bit;
> +	int cpu;
> +
> +	for_each_online_cpu(cpu) {
> +		old_cpumask_bit = cpumask_test_cpu(cpu, &rdtgrp->cpu_mask);
> +		new_cpumask_bit = cpumask_test_cpu(cpu, cpumask);
> +		/* Cannot clear a "cpus" bit in a rdtgroup. */
> +		if (old_cpumask_bit == 1 && new_cpumask_bit == 0)
> +			return -EINVAL;
> +	}
> +
> +	/* If a cpu is not online, cannot set it. */
> +	for_each_cpu(cpu, cpumask) {
> +		if (!cpu_online(cpu))
> +			return -EINVAL;
> +	}

cpumask_intersects() exists for a reason. And how is this protected against
cpu hotplug?

> +	list_for_each(l, &rdtgroup_lists) {
> +		r = list_entry(l, struct rdtgroup, rdtgroup_list);
> +		if (r == rdtgrp)
> +			continue;
> +
> +		for_each_cpu_and(cpu, &r->cpu_mask, cpumask)
> +			cpumask_clear_cpu(cpu, &r->cpu_mask);

This code clearly predates the invention of cpumask_andnot()

Thanks,

	tglx