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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 7AAC9FA3728 for ; Wed, 16 Oct 2019 23:35:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48AD4218DE for ; Wed, 16 Oct 2019 23:35:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pjftXlAf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388281AbfJPXfP (ORCPT ); Wed, 16 Oct 2019 19:35:15 -0400 Received: from mail-yw1-f68.google.com ([209.85.161.68]:38663 "EHLO mail-yw1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbfJPXfP (ORCPT ); Wed, 16 Oct 2019 19:35:15 -0400 Received: by mail-yw1-f68.google.com with SMTP id s6so217186ywe.5 for ; Wed, 16 Oct 2019 16:35:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9b/ul4mbGS02kxiuVy/n7L8yiMFa/DUQYAEdbStYXZk=; b=pjftXlAfQqwIDfYSP7pQTuLFXzgr6pBUaaoiFSRyYcUcKtBKHY5T5PkgvbzM4HgC75 EwBsVRrsfLY/Uu7YHKylx+E9I5Alx7akQD9DWo43J0gwh5cau8Vt/k+J3W0G/eZMr4f1 8HvFA422sgBPQTJIS8TK84oKosQu9XG3+8DG79lRM2I+LGr4oW8Q6l/P1zhhJhyOdEuc Wg00wGN7RnT4slv+dpf0nj0EU/hkBV3q2w1dqWPutp+K70NWZq6HPA5RCYyLApkh0bv6 J2uNF9nNYig7FE07np3r4mCCbWfVxfR/604g1EKsDtWgP3J9adcNZGG/qRraooB6cyid 0DmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9b/ul4mbGS02kxiuVy/n7L8yiMFa/DUQYAEdbStYXZk=; b=Ge9jiENzIK9DAyToLBq3wQmIxi3El/pQdC+n1MGQBD/B2gmlvyHmtLYWV9eZDasFKv SHCOiNmxg4/5OEZmtlfxd/zt1leb6u8Fi0fOGrtEL71Svwis2109qHUVtIzpYVgmQW6f Mym87MM6loM0+ODrPaMV9KsJcf7ZfEBfWO3YXU1A/sTZ5fe4C3HtoYPWPK0GD51SCn4N kmh9dnnBHZiBvDZ2Sz1oiEVQhqmPP+YwzRz4KNY6oycOFh2tWtDJe+r2AQxm5K0OdefG LWqpTIdGXvdfCgK/pd1Z/G+ywODAOu6HrT0gsYUg9ZyGzBSnximUz2UEgcszz9O7AZ27 oOOQ== X-Gm-Message-State: APjAAAWApAvDcMej3Z1pC1LeXSAACsakiMsvmhZ41hM0ANo0Op0JUNeq JBCrrxEF43/aGpqxLewnrujL6aRma2Ulfi95t2WTmA== X-Google-Smtp-Source: APXvYqwRe36J4EEAYNc6zevxBKOlyb/+DaLehRShj+Mu/VMPhx5KjQ3NX39TqSunH8o3mP2Ej4jbn6Ch32JSMymHV3Q= X-Received: by 2002:a81:8981:: with SMTP id z123mr649796ywf.92.1571268913833; Wed, 16 Oct 2019 16:35:13 -0700 (PDT) MIME-Version: 1.0 References: <20191014130438.163688-1-edumazet@google.com> <8142.1571268276@warthog.procyon.org.uk> In-Reply-To: <8142.1571268276@warthog.procyon.org.uk> From: Eric Dumazet Date: Wed, 16 Oct 2019 16:35:01 -0700 Message-ID: Subject: Re: [PATCH net] rxrpc: use rcu protection while reading sk->sk_user_data To: David Howells Cc: "David S . Miller" , netdev , Eric Dumazet , Jakub Kicinski Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Oct 16, 2019 at 4:24 PM David Howells wrote: > > Eric Dumazet wrote: > > > We need to extend the rcu_read_lock() section in rxrpc_error_report() > > and use rcu_dereference_sk_user_data() instead of plain access > > to sk->sk_user_data to make sure all rules are respected. > > Should I take it that the caller won't be guaranteed to be holding the RCU > read lock? > > Looking at __udp4_lib_err(), that calls __udp4_lib_err_encap(), which calls > __udp4_lib_err_encap_no_sk(), which should throw a warning if the RCU read > lock is not held. > > Similarly, icmp_socket_deliver() and icmpv6_notify() should also throw a > warning before calling ->err_handler(). > > Does that mean something further up the CPU stack is going to be holding the > RCU read lock? Note that before my patch, the code had a rcu_read_lock()/rcu_read_unlock(), so I only extended it. I am not sure that all callers already have rcu_read_lock() held, I prefer leaving this matter for net-next > > David