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=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 22742C4CEC9 for ; Wed, 18 Sep 2019 22:56:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E852B218AE for ; Wed, 18 Sep 2019 22:56:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NIXNsubd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730938AbfIRW4s (ORCPT ); Wed, 18 Sep 2019 18:56:48 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:44328 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730834AbfIRW4s (ORCPT ); Wed, 18 Sep 2019 18:56:48 -0400 Received: by mail-pl1-f196.google.com with SMTP id q15so633640pll.11 for ; Wed, 18 Sep 2019 15:56:48 -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=/KORqi9MvJK5DTujojrSlj9Cp7b9QjX7+k5d7WSJIeU=; b=NIXNsubd0M4/YmMZ4nLzujQswJVgCxwYEstBspiVVX0rkTNwUh6s0xinc+pBxdruf5 P/0Gx7ky8PD9m3vuIVPYqNF2quPFLuGEAmjUNzkikKPKR058FZLRVBiPIobPap+iFtQw 2vvG1oA6KwfLEUt3VRyImxG3N1reZ/2wH8veya7I1D3fQsIZCLPiWU5ZG39VnsKEf8pE 7RTDD6Y/YpiAlNQA0M7XoBQiRMCn83tHhUCFDC6Xy/9JDUP83ie6ghuVpik9Z37KKrtg xpRJyBZEWTvhs8BUvpH+hZWb+BZoXENXBb9ANwMQ3poVfnmVW3U6ZTsyvF06AIjf3n1m njCw== 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=/KORqi9MvJK5DTujojrSlj9Cp7b9QjX7+k5d7WSJIeU=; b=T743l6ERU+vvNQaXrgfEkAm4R2p9hQfyuPNVsJ7tFRdHBO1d7CxPO3S+w7gLrGSvpu XHHJIaieVRzQpfRotSK1xRT4pxuEGLK/A5OniWVqMOtkpMROlXFPORE24wmbdmqPlMHq s3RKmU4Z3WOUFEQlCQTFkPabWXkCziwj117b2rkoUdPC2gDh/6VrgGLM70xN5qEjjW4/ vpcpE9YoaASsIaRjrkFoO/tra3v7LKtQVZVBKQeqUV+zEkqL1DyvGBN46orLhArCzoc0 8l6bDU6y8sdJMmRZn/jk0t4b3QvJhxsvwQIGn7kRSP1IGx3urFKov5D8ppEHBwxdyqbI Oaog== X-Gm-Message-State: APjAAAXUMPkMFmah7H1aDN0nwUjZUFB2TjdsB52ZZ20Ps9VP9jA6w+6Y zj/rLnCPWbnaSG6k9PsZAFWjMNuYIhMPE1hvCYc= X-Google-Smtp-Source: APXvYqwVQvhd9nUiMO6RxsXX/NSbDXJYGrg9Zyst/UAZRzw+IWfKlRIlBcxl4iAkD1nOoj+M1wtP9shZWYBJ/1guFHc= X-Received: by 2002:a17:902:a5c5:: with SMTP id t5mr6426253plq.316.1568847407898; Wed, 18 Sep 2019 15:56:47 -0700 (PDT) MIME-Version: 1.0 References: <20190918073201.2320-1-vladbu@mellanox.com> <20190918073201.2320-3-vladbu@mellanox.com> In-Reply-To: <20190918073201.2320-3-vladbu@mellanox.com> From: Cong Wang Date: Wed, 18 Sep 2019 15:56:36 -0700 Message-ID: Subject: Re: [PATCH net 2/3] net: sched: multiq: don't call qdisc_put() while holding tree lock To: Vlad Buslov Cc: Linux Kernel Network Developers , Jamal Hadi Salim , Jiri Pirko , David Miller 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, Sep 18, 2019 at 12:32 AM Vlad Buslov wrote: > diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c > index e1087746f6a2..4cfa9a7bd29e 100644 > --- a/net/sched/sch_multiq.c > +++ b/net/sched/sch_multiq.c > @@ -187,18 +187,21 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt, > > sch_tree_lock(sch); > q->bands = qopt->bands; > + sch_tree_unlock(sch); > + > for (i = q->bands; i < q->max_bands; i++) { > if (q->queues[i] != &noop_qdisc) { > struct Qdisc *child = q->queues[i]; > > + sch_tree_lock(sch); > q->queues[i] = &noop_qdisc; > qdisc_tree_flush_backlog(child); > + sch_tree_unlock(sch); > + > qdisc_put(child); > } > } Repeatedly acquiring and releasing a spinlock in a loop does not seem to be a good idea. Is it possible to save those qdisc pointers to an array or something similar? Thanks.