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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BB81C433EF for ; Mon, 15 Nov 2021 14:44:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5A6E61BFA for ; Mon, 15 Nov 2021 14:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232180AbhKOOrA (ORCPT ); Mon, 15 Nov 2021 09:47:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231890AbhKOOqB (ORCPT ); Mon, 15 Nov 2021 09:46:01 -0500 Received: from mail-ed1-x52e.google.com (mail-ed1-x52e.google.com [IPv6:2a00:1450:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EEB2EC061766 for ; Mon, 15 Nov 2021 06:43:01 -0800 (PST) Received: by mail-ed1-x52e.google.com with SMTP id b15so72667056edd.7 for ; Mon, 15 Nov 2021 06:43:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=CzJK4JDX6paenq4KcCz6jy46RXs4ivoWCXDNifpXO7o=; b=saHYB+jmp8hyRGGN65aWHLlKWn7anwGLToUEK3BOGPGcu6a5PPmg+9HWsGf93RFbuk wzIzXI5sz75bfohzWYFahzSiOHV38X/dUt/UinkOXyjZZB2LBP4QzHPQmkYGkdoaX1NI jiRy2h9dUmdaC4YnQs8Ei6z+wKJB3Gdtu79HDc5YL5QYeJnKxNZEKiqixDHFDGGZgl/h LumvZzG2f6A1KXD44AcJZT0/qdSeW+PTas7tKmcay4ucwWmb+h4GJEW9x2TcgrlN1gTW 1ii3Ay3Ddo1XnwGTybmJRr4VAeNSFcIReeU5/K9GWV9eCzzbGSVt4HfM8M/NFH2KTIEH WjQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=CzJK4JDX6paenq4KcCz6jy46RXs4ivoWCXDNifpXO7o=; b=lVnalXvANp1TVNXN9RlAYYQlej9f7JZHfrlkbdPx/dyXxc+70h1hDOr9kqXIzX/niX 5L2FEViUsBAxS/rbuimbVFuOo4anVVWpPpMuk8fmCXQa8l/jT3Z+dwm5o90ffE4KsUTo YhEH0vM0EHfEuSx9+941ZXDgKP8gRqPbP9or1o5mVR5XbpeDAw/BBVHjh8dHG2tkW42V JdlmnPdV68D4LRZnCqAon19UAiKqR0dAvOBIYG9H2fuQqNh4hwvbM3Q9QeZtOwOaxzor CqOvKwVrMLzBuW7vY4j23H/cvbB8UqkHpEH3mPXyAQ5xbGfXaDWv16CYrQd4X7dAHkH1 FlAw== X-Gm-Message-State: AOAM532EBGIzRgVTMzX+hIAxeJPG2fOR77OXzB21ncpNUDq4k/W85ICo kwuiDYJ1UphmsKK5QNrbMf3W9g== X-Google-Smtp-Source: ABdhPJxmZIfHRDtPhNYfKcXFT56AD2cOKKPguslKGLKBF9rhwU+J5uDGnBOPJeNbHUgF5k93n+vz/g== X-Received: by 2002:a17:907:7f1a:: with SMTP id qf26mr49386530ejc.543.1636987380612; Mon, 15 Nov 2021 06:43:00 -0800 (PST) Received: from localhost (mail.chocen-mesto.cz. [85.163.43.2]) by smtp.gmail.com with ESMTPSA id k9sm7515183edo.87.2021.11.15.06.42.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Nov 2021 06:42:59 -0800 (PST) Date: Mon, 15 Nov 2021 15:42:58 +0100 From: Jiri Pirko To: Jason Gunthorpe Cc: Leon Romanovsky , Jakub Kicinski , Jiri Pirko , Ido Schimmel , "David S . Miller" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, edwin.peer@broadcom.com Subject: Re: [PATCH net-next] devlink: Require devlink lock during device reload Message-ID: References: <20211109070702.17364ec7@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20211109153335.GH1740502@nvidia.com> <20211109082042.31cf29c3@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20211109182427.GJ1740502@nvidia.com> <20211115125359.GM2105516@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211115125359.GM2105516@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mon, Nov 15, 2021 at 01:53:59PM CET, jgg@nvidia.com wrote: >On Mon, Nov 15, 2021 at 12:20:21PM +0100, Jiri Pirko wrote: >> Sun, Nov 14, 2021 at 07:19:02AM CET, leon@kernel.org wrote: >> >On Fri, Nov 12, 2021 at 08:38:56AM +0100, Jiri Pirko wrote: >> >> Thu, Nov 11, 2021 at 01:17:52PM CET, leon@kernel.org wrote: >> >> >On Thu, Nov 11, 2021 at 01:05:11PM +0100, Jiri Pirko wrote: >> >> >> Tue, Nov 09, 2021 at 07:24:27PM CET, jgg@nvidia.com wrote: >> >> >> >On Tue, Nov 09, 2021 at 08:20:42AM -0800, Jakub Kicinski wrote: >> >> >> >> On Tue, 9 Nov 2021 11:33:35 -0400 Jason Gunthorpe wrote: >> >> >> >> > > > I once sketched out fixing this by removing the need to hold the >> >> >> >> > > > per_net_rwsem just for list iteration, which in turn avoids holding it >> >> >> >> > > > over the devlink reload paths. It seemed like a reasonable step toward >> >> >> >> > > > finer grained locking. >> >> >> >> > > >> >> >> >> > > Seems to me the locking is just a symptom. >> >> >> >> > >> >> >> >> > My fear is this reload during net ns destruction is devlink uAPI now >> >> >> >> > and, yes it may be only a symptom, but the root cause may be unfixable >> >> >> >> > uAPI constraints. >> >> >> >> >> >> >> >> If I'm reading this right it locks up 100% of the time, what is a uAPI >> >> >> >> for? DoS? ;) >> >> >> >> >> >> >> >> Hence my questions about the actual use cases. >> >> >> > >> >> >> >Removing namespace support from devlink would solve the crasher. I >> >> >> >certainly didn't feel bold enough to suggest such a thing :) >> >> >> > >> >> >> >If no other devlink driver cares about this it is probably the best >> >> >> >idea. >> >> >> >> >> >> Devlink namespace support is not generic, not related to any driver. >> >> > >> >> >What do you mean? >> >> > >> >> >devlink_pernet_pre_exit() calls to devlink reload, which means that only >> >> >drivers that support reload care about it. The reload is driver thing. >> >> >> >> However, Jason was talking about "namespace support removal from >> >> devlink".. >> > >> >The code that sparkles deadlocks is in devlink_pernet_pre_exit() and >> >this will be nice to remove. I just don't know if it is possible to do >> >without ripping whole namespace support from devlink. >> >> As discussed offline, the non-standard mlx5/IB usage of network >> namespaces requires non standard mlx5/IB workaround. Does not make any >> sense to remove the devlink net namespace support removal. > >Sorry, I don't agree that registering a net notifier in an aux device >probe function is non-standard or wrong. Listening to events which happen in different namespaces and react to them is the non-standard behaviour which I refered to. If you would not need to do it, you could just use netns notofier which would solve your issue. You know it. > >This model must be supported sanely somehow in the netdev area and >cannot be worked around in leaf drivers. > >Intel ice will have the same problem, as would broadcom if they ever >get their driver modernized. > >Jason