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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 D4276C433DF for ; Mon, 6 Jul 2020 19:21:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B236A206B6 for ; Mon, 6 Jul 2020 19:21:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KnQ/Qg4f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726542AbgGFTVp (ORCPT ); Mon, 6 Jul 2020 15:21:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725942AbgGFTVp (ORCPT ); Mon, 6 Jul 2020 15:21:45 -0400 Received: from mail-io1-xd44.google.com (mail-io1-xd44.google.com [IPv6:2607:f8b0:4864:20::d44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34ABCC061755 for ; Mon, 6 Jul 2020 12:21:45 -0700 (PDT) Received: by mail-io1-xd44.google.com with SMTP id f6so25021404ioj.5 for ; Mon, 06 Jul 2020 12:21:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=oZA63vFpCn3oFOpSFuQ0TFjLkURfFPWwShJPxeaHrO4=; b=KnQ/Qg4fLebp63ArTGo2tokGyryfLLF2FAnm+PI30BQAXxlPfpKVtAto6AwyorCv4j PBQ/FHGGFGG7moWSik3M7pizwk34uae0nT5hUw9mG49e0h+l4j/D9G4ed1+4PbiUAIZo S0tahXPLukmNrgMaVkAaO3+u8OECX47OAj5uupNrFpgBmmT0z03yOUgkz0w/2zO+YrSy rPrgiUTPlCTmiBMgwlGWisQV02Zg74BjxvshD064TUKxyNVPS3KYQW4MKHeJSdGxTDbp Xi8qQGFsoTygI/9yrWkwa2H5QDhZ//wzfPGa1fKVoO2AJPcyKl4rr4HQcyJVQlhPnEna 0zUQ== 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=oZA63vFpCn3oFOpSFuQ0TFjLkURfFPWwShJPxeaHrO4=; b=jicNJeta5ZiMyBx2oV0cVdsLlT1lQIFczERlLfGIgKcuLf1pccOJnMyyLtDHGRzPBX F8iwL79tqBTaG/IN0XAsOaPiyHp3RKI4E8I8ctMl+aDZiEievTAVcLGy3nPt0KAJh/p1 lGq+kKJ9HFEXm9EIUqG6LAhQtPuW/F7Nf8MzkWu7jKKJStDjSjdDX16ReVcwuB+sk61G 8WOga61E1kJXx7nSXhFKLI79LPRia87bvyf47UGcRmkNFmV+QDoRRI34MixwL1SjjmM2 08IXGvDyOcSZiRCuwcp+cEZluoAoOeeKacRtU/5z1xea/rMiPID6lziTt3Qkzin6uyNa gg+w== X-Gm-Message-State: AOAM533FdlDIuASw4uJ8y8lERsoWM/7AywDvpVkNqxqHrHq7OIkqleBu isJ2lHVDGoQPLyK+WiB5dX6ieyvYFJQ3yAG0BcI= X-Google-Smtp-Source: ABdhPJwUBbXlzKvXQCGIhAHttrFWp5PCN+0gha8b9XOP/l5OMuxXc3m5rn/1Wz2ecr4MuBXCYTZ2OwdM+JLBcn0enXY= X-Received: by 2002:a02:c785:: with SMTP id n5mr55979560jao.75.1594063304502; Mon, 06 Jul 2020 12:21:44 -0700 (PDT) MIME-Version: 1.0 References: <643ef0859371d3bf6280f5014d668fb18b3b6d85.1593209494.git.petrm@mellanox.com> In-Reply-To: <643ef0859371d3bf6280f5014d668fb18b3b6d85.1593209494.git.petrm@mellanox.com> From: Cong Wang Date: Mon, 6 Jul 2020 12:21:33 -0700 Message-ID: Subject: Re: [PATCH net-next v1 1/5] net: sched: Pass root lock to Qdisc_ops.enqueue To: Petr Machata Cc: Linux Kernel Network Developers , David Miller , Jakub Kicinski , Eric Dumazet , Jiri Pirko , Ido Schimmel 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 Fri, Jun 26, 2020 at 3:46 PM Petr Machata wrote: > > A following patch introduces qevents, points in qdisc algorithm where > packet can be processed by user-defined filters. Should this processing > lead to a situation where a new packet is to be enqueued on the same port, > holding the root lock would lead to deadlocks. To solve the issue, qevent > handler needs to unlock and relock the root lock when necessary. > > To that end, add the root lock argument to the qdisc op enqueue, and > propagate throughout. Hmm, but why do you pass root lock down to each ->enqueue()? You can find root lock with sch_tree_lock() (or qdisc_lock() if you don't care about hierarchy), and you already have qdisc as a parameter of tcf_qevent_handle(). Thanks.