linux-kernel - Re: [PATCH] x86: Add check for number of available vectors before CPU down [v4]

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 2 Jan 2014 21:25:24 -0500
From:	"Chen, Gong" <gong.chen@...ux.intel.com>
To:	Prarit Bhargava <prarit@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Michel Lespinasse <walken@...gle.com>,
	Seiji Aguchi <seiji.aguchi@....com>,
	Yang Zhang <yang.z.zhang@...el.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Janet Morgan <janet.morgan@...el.com>,
	Tony Luck <tony.luck@...el.com>,
	Ruiv Wang <ruiv.wang@...il.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org
Subject: Re: [PATCH] x86: Add check for number of available vectors before
 CPU down [v4]

Add some nitpicks below.

Reviewed-by: Chen, Gong <gong.chen@...ux.intel.com>

On Thu, Jan 02, 2014 at 07:47:24PM -0500, Prarit Bhargava wrote:
> +int check_irq_vectors_for_cpu_disable(void)
> +{
> +	int irq, cpu;
> +	unsigned int vector, this_count, count;
> +	struct irq_desc *desc;
> +	struct irq_data *data;
> +	struct cpumask affinity_new, online_new;
> +
> +	cpumask_copy(&online_new, cpu_online_mask);
> +	cpu_clear(smp_processor_id(), online_new);
I notice that you use smp_processor_id() many times. Maybe we can
save it first for speed.

> +
> +	this_count = 0;
> +	for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
> +		irq = __this_cpu_read(vector_irq[vector]);
> +		if (irq >= 0) {
> +			desc = irq_to_desc(irq);
> +			data = irq_desc_get_irq_data(desc);
> +			cpumask_copy(&affinity_new, data->affinity);
> +			cpu_clear(smp_processor_id(), affinity_new);
> +			/*
> +			 * Only count active non-percpu irqs, and those
> +			 * irqs that are not linked to on an online cpu; in
> +			 * fixup_irqs(), chip->irq_set_affinity() will be
> +			 * called which will set vector_irq[irq] for each
> +			 * cpu.
> +			 */
> +			if (irq_has_action(irq) && !irqd_is_per_cpu(data) &&
> +			    (cpumask_empty(&affinity_new) ||
> +			     !cpumask_subset(&affinity_new, &online_new)))
> +				this_count++;
Would you please add some extra comments to describe these two different
conditions that cpumask is empty and non-empty. I feel it is a little bit
sutble and I don't expect I'm confused by myself one day :-).


Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)