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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1A7AFC3DA4A for ; Fri, 2 Aug 2024 01:40:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tAxmJ0tqkRDZBgyz541R5lAT9DJbuioajG4yXwr7Ng0=; b=R7MfflZ5pi+Dq/XeMVYTjJ07IX 9sdVKd6+CTZ8bb+8D7Ypb5LEXvWxh4hgS8ZRiCmihRuktoTaLwEjfwkO4O/GzE7j23GKZqZ7vXfsY Gs7D0e4ncV7UUsClriqfyzh2jZHcYwDjDJAXuGGgVSDoT9CoKXgXg2j6gc2Fgfe8yi+E9sSjpHdUN AkqV+LGVLgRcLh2MWBHHXJxDeJxu48cv2mmgm/EqzEsnE996juIeeIe0R5aul8yM7myWtJX6Lmzys TMD96BMYuGjR+yNxFaveCUvRqhi9/U+AzeQvf57TJCNslKEamkk+otVh15soF9HrQX9h19tLNgz/T jMkWFoGA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZhHE-00000007IpW-2bj3; Fri, 02 Aug 2024 01:40:16 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZhGi-00000007Ifb-1iTp for linux-arm-kernel@lists.infradead.org; Fri, 02 Aug 2024 01:39:46 +0000 Received: from mail.maildlp.com (unknown [172.19.163.17]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4WZpKt6Qhmz1S71V; Fri, 2 Aug 2024 09:34:58 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 46B871A0188; Fri, 2 Aug 2024 09:39:35 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 2 Aug 2024 09:39:34 +0800 Message-ID: Date: Fri, 2 Aug 2024 09:39:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] ARM: smp: Fix missing backtrace IPI statics Content-Language: en-US To: "Russell King (Oracle)" CC: , , , , , , References: <20240801094022.1402616-1-ruanjinjie@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemi100008.china.huawei.com (7.221.188.57) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240801_183944_644497_1EEC8E45 X-CRM114-Status: GOOD ( 11.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024/8/2 0:36, Russell King (Oracle) wrote: > On Thu, Aug 01, 2024 at 05:40:22PM +0800, Jinjie Ruan wrote: >> It is similar to ARM64 commit 916b93f4e865 ("arm64: smp: Fix missing IPI >> statistics"), commit 56afcd3dbd19 ("ARM: Allow IPIs to be handled as normal >> interrupts") set CPU_BACKTRACE IPI "IRQ_HIDDEN" flag but not show it in >> show_ipi_list(), which cause the interrupt kstat_irqs accounting >> is missing in display. > > I don't see why this needs to be included. If this IPI fires, it means > that the kernel has suffered a lockup and is probably not very useful. > So the chances of being able to read out from /proc/interrupts a non- > zero "CPU backtrace interrupts" figure is highly unlikely. It is more of a change than a bug. If we reset the arm32 code to before commit 56afcd3dbd19 ("ARM: Allow IPIs to be handled as normal interrupts"), the backtrace IPI statics is shown ok as below, but after that it is missing: / # cat /proc/interrupts CPU0 24: 6 GIC-0 34 Level timer 25: 469 GIC-0 29 Level twd 26: 61 GIC-0 75 Edge virtio0 29: 8 GIC-0 44 Level kmi-pl050 30: 118 GIC-0 45 Level kmi-pl050 31: 0 GIC-0 36 Level rtc-pl031 32: 0 GIC-0 41 Level mmci-pl18x (cmd) 33: 0 GIC-0 42 Level mmci-pl18x (pio) 34: 0 GIC-0 92 Level arm-pmu 35: 0 GIC-0 93 Level arm-pmu 36: 0 GIC-0 94 Level arm-pmu 37: 0 GIC-0 95 Level arm-pmu 39: 15 GIC-0 37 Level uart-pl011 IPI0: 0 CPU wakeup interrupts IPI1: 0 Timer broadcast interrupts IPI2: 0 Rescheduling interrupts IPI3: 0 Function call interrupts IPI4: 0 CPU stop interrupts IPI5: 0 IRQ work interrupts IPI6: 0 completion interrupts IPI7: 0 CPU backtrace interrupts > > So, I don't see much point to this change. >