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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 AAF7DC64E7B for ; Mon, 30 Nov 2020 20:22:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 418AF207F7 for ; Mon, 30 Nov 2020 20:22:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=networkplumber-org.20150623.gappssmtp.com header.i=@networkplumber-org.20150623.gappssmtp.com header.b="MirysheB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388447AbgK3UWb (ORCPT ); Mon, 30 Nov 2020 15:22:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388439AbgK3UWa (ORCPT ); Mon, 30 Nov 2020 15:22:30 -0500 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B3FAC0613D2 for ; Mon, 30 Nov 2020 12:21:44 -0800 (PST) Received: by mail-pl1-x632.google.com with SMTP id x15so7129090pll.2 for ; Mon, 30 Nov 2020 12:21:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=bVAL/0KHxhPmWrWql10z/ecLv3R1nEV27Wu012m5/DE=; b=MirysheBGpGwwcIylMjeuA0z2w4YcENJEwyRqBWg6IHZSop3eSl94Eajjn3rkracyr c38WSybhu1yLzjD2/zkxfcFO7UfP11G1LqZ8FpCtk5Sp/5wknNn0+RgjSrHHGZgXCCa8 VAg3+/3YvBEm9dw1Feb1YzNgY3tQC6TEAZzU6jBLZYQLDg31hQ4pqQ15uUxgQPuQFY6X gkb9s6gwag/P0Us7x8diYocQRv1kYGgwizm0WafYqVp2EAxKTcSfRGuIl3zzsVCw/Dge txBubp1k5fj7fsUDp7EhBcGyplQWGB044KCDYRrjfeeKjoDScdL1Co0J+x2Bj+Omf4xy YDWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bVAL/0KHxhPmWrWql10z/ecLv3R1nEV27Wu012m5/DE=; b=GyS2vgCFXEa+oLM1Qs3xkNnSNm6wHb6pn8BdwbbhXSW0mlMo5fQNFjpGYPVT9plNw0 mTKQxJ2snsOsVLz489BMgNmWB/SVYwI0ASbXqCjTS5OA9AvcwcaDSOt62tC3Lwn3nV+0 nCiG+F/UgzsGU6KvMN+2tPZz/Sgx/hJi7hNM7tWxaKEJpmSmKhkZShncAnF1xWDqT9DA DXRUTFLmRPsZ0NH0SNtINNzeClzoJIFSH0PLgFiLt2hnSlJZM0+aQ+75czl4xXjX0M7i d/zpglU1DjWhpGar6JlDn0kMcPkDQu+0JTAHuDrhbv2DPEK+7Yup4dMfMbyRpWBtMokj R5Ew== X-Gm-Message-State: AOAM530ewRI+1n3ueuaZarMluRqEYyJEfm8IxdqqS0O1mdD5F3Bz+3WP r06kQn2eMxlcUP66AP7oj+EimA== X-Google-Smtp-Source: ABdhPJxMurDipXQqcGqSxe1gpLPKEk92H62vEB5df9y++5c2mMJ12gbtN6WGJdHerNPGtq3oF3WYJg== X-Received: by 2002:a17:90b:110:: with SMTP id p16mr683344pjz.54.1606767704028; Mon, 30 Nov 2020 12:21:44 -0800 (PST) Received: from hermes.local (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id f18sm17932668pfa.167.2020.11.30.12.21.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Nov 2020 12:21:43 -0800 (PST) Date: Mon, 30 Nov 2020 12:21:29 -0800 From: Stephen Hemminger To: Vladimir Oltean Cc: Eric Dumazet , Eric Dumazet , Jakub Kicinski , netdev , Paul Gortmaker , Jiri Benc , Or Gerlitz , Cong Wang , Jamal Hadi Salim , Andrew Lunn , Florian Fainelli Subject: Re: Correct usage of dev_base_lock in 2020 Message-ID: <20201130122129.21f9a910@hermes.local> In-Reply-To: <20201130194617.kzfltaqccbbfq6jr@skbuf> 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> <20201130194617.kzfltaqccbbfq6jr@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 30 Nov 2020 21:46:17 +0200 Vladimir Oltean wrote: > On Mon, Nov 30, 2020 at 08:22:01PM +0100, Eric Dumazet wrote: > > And ? > > > > A bonding device can absolutely maintain a private list, ready for > > bonding ndo_get_stats() use, regardless > > of register/unregister logic. > > > > bond_for_each_slave() is simply a macro, you can replace it by something else. > > Also, coming to take the comment at face value. > Can it really? How? Freeing a net_device at unregister time happens > after an RCU grace period. So whatever the bonding driver does to keep a > private list of slave devices, those pointers need to be under RCU > protection. And that doesn't help with the sleepable context that we're > looking for. if device is in a private list (in bond device), the way to handle this is to use dev_hold() to keep a ref count.