From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7D2DC433DF for ; Sat, 22 Aug 2020 09:33:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF11720738 for ; Sat, 22 Aug 2020 09:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726730AbgHVJdw (ORCPT ); Sat, 22 Aug 2020 05:33:52 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:55860 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725864AbgHVJdv (ORCPT ); Sat, 22 Aug 2020 05:33:51 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 08303A10FBACB14A5A30 for ; Sat, 22 Aug 2020 17:33:50 +0800 (CST) Received: from [127.0.0.1] (10.174.177.157) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.487.0; Sat, 22 Aug 2020 17:33:40 +0800 Subject: Re: [PATCH] genirq/proc: Show percpu irq affinity To: Thomas Gleixner CC: , Shiyuan Hu , Hewenliang References: <874kp754s6.fsf@nanos.tec.linutronix.de> From: Yunfeng Ye Message-ID: Date: Sat, 22 Aug 2020 17:33:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <874kp754s6.fsf@nanos.tec.linutronix.de> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.157] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/8/13 16:27, Thomas Gleixner wrote: > Yunfeng Ye writes: > >> When the "affinity=" cmdline parameter is configured, > > There is no such parameter. > >> the interrupt affinity displayed in the proc directory does not match >> with that of the the percu interrupt, and the percu interrupt uses >> desc->percu_affinity. > > And when the non-existing parameter is not on the command line then > irq->affinity is showing the correct value magically? > > Definitely not: It's unconditionally showing irq->affinity and that is > pretty unlikely to match irq->percpu_affinity in any case. > Sorry，it is "irqaffinity=" cmdline parameter. it will set irq_default_affinity mask. if the interrupt is not the managed irq, the irq_desc will use irq_default_affinity as default affinity. For example, the cmdline "irqaffinity=0,1,126,127" on the 128 cores system： [root@localhost ~]# cat /proc/irq/4/smp_affinity_list 0-1,126-127 The irq 4 is "arch_timer" interrupt, which is a percpu interrupt. So is it necessary to show the percpu irq affinity correct? thanks. >> diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c >> index 32c071d7bc03..b9d0fa87b4b4 100644 >> --- a/kernel/irq/proc.c >> +++ b/kernel/irq/proc.c >> @@ -52,6 +52,8 @@ static int show_irq_affinity(int type, struct seq_file *m) >> case AFFINITY: >> case AFFINITY_LIST: >> mask = desc->irq_common_data.affinity; >> + if (irqd_is_per_cpu(&desc->irq_data)) >> + mask = desc->percpu_affinity; > > This breaks all architecture which mark interrupts as per CPU without > using the partition mechanism resulting in a NULL pointer dereference. > Yes, it is a problem. > Thanks, > > tglx > > . >