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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C54FC77B76 for ; Sun, 16 Apr 2023 23:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229536AbjDPXIN (ORCPT ); Sun, 16 Apr 2023 19:08:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45562 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229484AbjDPXIM (ORCPT ); Sun, 16 Apr 2023 19:08:12 -0400 Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06D752108 for ; Sun, 16 Apr 2023 16:08:12 -0700 (PDT) Received: by mail-pl1-x633.google.com with SMTP id p17so12620200pla.3 for ; Sun, 16 Apr 2023 16:08:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681686490; x=1684278490; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=RT0tuZZilKuzj7md7XFaZUJKFbSDRsiyEtzr0wYj6ZM=; b=Ql5ciPSoQkd5BX+3HcLCToFULpxVrcQiHPq/7c6MaOgeCDLWaItuIdXoEODL9uiiGV YR4K8EXjDRwxRO+eiXg3TzGFWnFUvrDsUUmbOCrf4IdEzG0OJfGwN4RTUSxcMR5gCfZn j9WwPmDArFGjcWhGHJn+/Y2Ul/Jx/MK+kE4QawPQEynDFIMei03gJ6J2KpXCFjzSoWya blModjTPQWx+43X/Akmn7axT6twT86dxHen/jKLRvzNkOBIoQcfWcoFKfB+Lr+MPj2Vg UPLaHidSpVWl6xhR6yeO0ezVBB/malku8yd7J39uQAfeSZ9kV28vQM+G0ljQBg/3w1rg 33yQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681686490; x=1684278490; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=RT0tuZZilKuzj7md7XFaZUJKFbSDRsiyEtzr0wYj6ZM=; b=Zx80RmjBiWiMB/PpzN3fnKg7IVY25JRa94eoMoJ6/aJ1IMDF4klVVQz/uR7JGVoIzi AbsERSNAdC04Wglt6z+OHGgsQETpLnVGbL4aTVXPsuc57J1YEZcXKLKCpgqrrdXoVjoo mAtK2wn+1FbCDJr0mPeaw+CLuzCkM2vdxIiBNKAwhhrIqtKzm2J2PgaBB9JldGA8rINj bnBsQ7MVVI0KVLF41660jWpa7kLu5SQwz6E8uMXvZAxh0HokFF1disKNexWbAszQOHvT CRra0YaL7D5AhfOSbTtf91zQJHHs6ehJycm7maeHVWPz4kqQvBQ9AOQvvP1E78FDcArE yzCQ== X-Gm-Message-State: AAQBX9eGkAq+nHfAHeeaBLLaPMGvmu40Jx3JUfb0r3OMAzyo+e9I2I+S HNEiucqcdv9eacZB2L9eoJM= X-Google-Smtp-Source: AKy350aoLS1bCRI8o78VYiPTj1BgkiTbUQpfKzhvqZD6VP4HuINAXVW94cVsTQOQAhIzl9SxLOqUOg== X-Received: by 2002:a17:902:c408:b0:19e:baa6:5860 with SMTP id k8-20020a170902c40800b0019ebaa65860mr13044264plk.2.1681686490492; Sun, 16 Apr 2023 16:08:10 -0700 (PDT) Received: from Laptop-X1 ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id jj6-20020a170903048600b001a5059861adsm6369314plb.224.2023.04.16.16.08.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Apr 2023 16:08:09 -0700 (PDT) Date: Mon, 17 Apr 2023 07:08:03 +0800 From: Hangbin Liu To: Jakub Kicinski Cc: netdev@vger.kernel.org, Jay Vosburgh , "David S . Miller" , Jonathan Toppins , Paolo Abeni , Eric Dumazet , Liang Li , Simon Horman , Miroslav Lichvar Subject: Re: [PATCHv4 net-next] bonding: add software tx timestamping support Message-ID: References: <20230414083526.1984362-1-liuhangbin@gmail.com> <20230414180205.1220135d@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230414180205.1220135d@kernel.org> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Apr 14, 2023 at 06:02:05PM -0700, Jakub Kicinski wrote: > On Fri, 14 Apr 2023 16:35:26 +0800 Hangbin Liu wrote: > > v4: add ASSERT_RTNL to make sure bond_ethtool_get_ts_info() called via > > RTNL. Only check _TX_SOFTWARE for the slaves. > > > + ASSERT_RTNL(); > > + > > rcu_read_lock(); > > real_dev = bond_option_active_slave_get_rcu(bond); > > dev_hold(real_dev); > > @@ -5707,10 +5713,36 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev, > > ret = ops->get_ts_info(real_dev, info); > > goto out; > > } > > + } else { > > + /* Check if all slaves support software tx timestamping */ > > + rcu_read_lock(); > > + bond_for_each_slave_rcu(bond, slave, iter) { > > > + ret = -1; > > + ops = slave->dev->ethtool_ops; > > + phydev = slave->dev->phydev; > > + > > + if (phy_has_tsinfo(phydev)) > > + ret = phy_ts_info(phydev, &ts_info); > > + else if (ops->get_ts_info) > > + ret = ops->get_ts_info(slave->dev, &ts_info); > > My comment about this path being under rtnl was to point out that we > don't need the RCU protection to iterate over the slaves. This is > a bit of a guess, I don't know bonding, but can we not use > bond_for_each_slave() ? Sorry, I misunderstood your comment in patchv3. I thought you agreed to use the same use case like rlb_next_rx_slave(). I will post a new fix version. > > As a general rule we should let all driver callbacks sleep. Drivers > may need to consult the FW or read something over a slow asynchronous > bus which requires process / non-atomic context. RCU lock puts us in > an atomic context. And ->get_ts_info() is a driver callback. > > It's not a deal breaker if we can't avoid RCU, but if we can - we should > let the drivers sleep. Sorry if I wasn't very clear previously. Thanks for the explanation. Regards Hangbin