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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 0CB80C71155 for ; Mon, 30 Nov 2020 21:42:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9085E2085B for ; Mon, 30 Nov 2020 21:42:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PTXjDi7d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730114AbgK3VmI (ORCPT ); Mon, 30 Nov 2020 16:42:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726979AbgK3VmH (ORCPT ); Mon, 30 Nov 2020 16:42:07 -0500 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A0C0C0613CF for ; Mon, 30 Nov 2020 13:41:27 -0800 (PST) Received: by mail-pg1-x52c.google.com with SMTP id s63so10888515pgc.8 for ; Mon, 30 Nov 2020 13:41:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=/66KycfDuJ4iQrviEddUKKGhdqc8PmfjAOsXXwQ2xLc=; b=PTXjDi7dpNQiMuQ1rqC7aehLerXOYUVUZejHxjFTOs/qCNm0Y1spjgPP77GzMSDyFM +DmzvYxxIul6S6v/OO155E5vPaZRDIiL8z/il/jUIwOhEm1N+Mreurxi8O5uQO6AKSk6 Nq1BhW7r+LfiGYSMSt8eiMEhH1kAHw/8Tq2haljCtMoS3dZn1VukPj3fp/5DFfZ0MJ9K CrJ0GXBctDXUkuDnxFEe+rql8IT3UITjjhRru3lcKNoPO3ajJNGXHIYDaQgyz/VwX+fU OkeHGqULpoCpenjYLwJQ56azA7H9f035mkNvHhBXOhVoRJEosv/xYrRUvfRRy1uq+Sgq D1DQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=/66KycfDuJ4iQrviEddUKKGhdqc8PmfjAOsXXwQ2xLc=; b=f4kNSbj9FCE/5BCM/BzkrI0DOxuZuayeRPIgeA+fIbafqGDSunvEjGYJ8bqNZH/Awj m8g67LN02UO2N4RhN4W4VIkoMh3w7624X9B2lF3PESZEElqlZxyxcV7XuHCBf0utzmtx p3ojedY6eo/baTo8VTJSOiVUOYDcBmoUsoazml3XfqkI05OLAk32tsS8er3CgLlPihOk LS9XT2UlzvkPVdmVQUwHKk+N37B9hl3BMQldgK8WQ7Wz1E2sBzI8cUleSrMrCmxE3LMW BTbbITwZF8j+uGdnbWscsD1O3K+k6Qq112ZhLCNQgw5bcoCGSe19jJ2ZiUH5LAIi7JDL A2Hg== X-Gm-Message-State: AOAM5315hUM+TNRq/HTex8v/tY5YSNvxjR9CXQrToYs2nicvBwnzv4fh aeJQ0HsxLKsjJZDvnIQ5tGGPxd+ezFQ= X-Google-Smtp-Source: ABdhPJxg/3gKv5bYX/zzK93uv5xpmD0qX2eyYo9sLeZ3vOlwAPGlGAMwBJonMJq7XFMF+yqArdfApg== X-Received: by 2002:a63:4d07:: with SMTP id a7mr19993187pgb.274.1606772486032; Mon, 30 Nov 2020 13:41:26 -0800 (PST) Received: from [10.230.28.242] ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id q12sm16864768pgv.91.2020.11.30.13.41.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Nov 2020 13:41:25 -0800 (PST) To: Vladimir Oltean , Eric Dumazet Cc: Eric Dumazet , Jakub Kicinski , Stephen Hemminger , netdev , Paul Gortmaker , Jiri Benc , Or Gerlitz , Cong Wang , Jamal Hadi Salim , Andrew Lunn References: <20201129182435.jgqfjbekqmmtaief@skbuf> <20201129205817.hti2l4hm2fbp2iwy@skbuf> <20201129211230.4d704931@hermes.local> <20201130101405.73901b17@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> <20201130184828.x56bwxxiwydsxt3k@skbuf> <20201130190348.ayg7yn5fieyr4ksy@skbuf> <20201130193230.f5aopdmcc5x3ldey@skbuf> From: Florian Fainelli Subject: Re: Correct usage of dev_base_lock in 2020 Message-ID: Date: Mon, 30 Nov 2020 13:41:23 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201130193230.f5aopdmcc5x3ldey@skbuf> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 11/30/2020 11:32 AM, Vladimir Oltean wrote: > -----------------------------[cut here]----------------------------- > From 93ffc25f30849aaf89e50e58d32b0b047831f94d Mon Sep 17 00:00:00 2001 > From: Vladimir Oltean > Date: Mon, 30 Nov 2020 02:49:25 +0200 > Subject: [PATCH] parisc/led: retrieve device statistics under RTNL, not RCU > > In the effort of making .ndo_get_stats64 be able to sleep, we need to > ensure the callers of dev_get_stats do not use atomic context. > > The LED driver for HP-PARISC workstations uses a workqueue to > periodically check for updates in network interface statistics, and > flicker when those have changed (i.e. there has been activity on the > line). Honestly that is a strange idea even when protected by RCU, but > now, the dev_get_stats call can sleep, and iterating through the list of > network interfaces still needs to ensure the integrity of list of > network interfaces. So that leaves us only one locking option given the > current design of the network stack, and that is the RTNL mutex. In the > future we might be able to make this a little bit less expensive by > creating a separate mutex for the list of network interfaces. We have a netdev LED trigger under drivers/leds/trigger/ledtrig-netdev.c that appears to be nicely duplicating this LED driver. -- Florian