From patchwork Mon Jul 20 07:22:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Pirko X-Patchwork-Id: 1332067 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=resnulli.us Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=resnulli-us.20150623.gappssmtp.com header.i=@resnulli-us.20150623.gappssmtp.com header.a=rsa-sha256 header.s=20150623 header.b=Xx7l0FdL; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B9Cqd4RJyz9sRW for ; Mon, 20 Jul 2020 17:22:53 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727090AbgGTHWw (ORCPT ); Mon, 20 Jul 2020 03:22:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725815AbgGTHWw (ORCPT ); Mon, 20 Jul 2020 03:22:52 -0400 Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B360C061794 for ; Mon, 20 Jul 2020 00:22:52 -0700 (PDT) Received: by mail-wm1-x342.google.com with SMTP id w3so24043570wmi.4 for ; Mon, 20 Jul 2020 00:22:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=uaa56VYlto7LGl6KsuvxoQ2JUEPsf/KVQDkhD+6cdeE=; b=Xx7l0FdLGLpxXUayW8rsp998bLt0ErxCT9A7SUnaIDNMuEhK1ZnRvR1vCp03z+S4Yb cUkXeLPafoZXYVHia/+Vp8rS6RSoPbRj5JROR4T4p1OPv1GQ85qX6UJvkPY6350rRoVm jMnB1szSuddLaP70hVr9ZLrl9Ij5oyjfLGLIWo00Jo0Od1Io5X/nF/JvXRdw1u0BB32M dyzqmXFcIhnnRaNW5/a4qjJlMliaZeG6CyKQg3pQ0wtNspmq5z5PEsgX6kVaCHTWXjPa xWawqtkjqSkyPjiRf9DOibZJWUxHZlQ01Fc8Rvy6oK3nhP/NFl49eeD/1r5xSqPzHIZi Jdbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=uaa56VYlto7LGl6KsuvxoQ2JUEPsf/KVQDkhD+6cdeE=; b=icjqan0FYkMGpt63QnvN6PfOPPb+qmZvPEOk5PFawlnLxdW2jkjvMlFgmBA9D55X7a EJgiI8pMblRgjzh4yg2e3wvAUXCGWktKmgURkzR589bN176DEtV55JJdaxuJAKI2psTQ DZjsCq20ZzW1v5KlGZcni8c1jmgxEUBzgbF4EVbaXMK8jqzd345TEWkeCaVLiN8MYG1s 950hSnyeeRPiPvDa2ZBpmPveMT5eUR1y8+aF48lpmLcr2Vm0dMQVpKMVeqKifwxqnAlJ +zBItudTRoAOwa7kkrOLskIyr6XfEQNeUztUQ8sl2mkRk3BEQNc1VMUgUuZPikhctYLt hqIw== X-Gm-Message-State: AOAM533n+rpj6mgvaPqlW4yyhzeT0ST4v5yYAByOTU8o5DTzXCfDJluD WbnntMhuVLq+yvynjCaTXx7kQ/h+PPM= X-Google-Smtp-Source: ABdhPJwqvHCVKLchwOh7dTbmj/qGsmyB5VLNUIOzRNCjzbgttey+f+AFrdLL9ppdkgtEib2qJgtfWQ== X-Received: by 2002:a05:600c:2253:: with SMTP id a19mr19308860wmm.136.1595229770393; Mon, 20 Jul 2020 00:22:50 -0700 (PDT) Received: from localhost (ip-89-103-111-149.net.upcbroadband.cz. [89.103.111.149]) by smtp.gmail.com with ESMTPSA id x1sm31440441wrp.10.2020.07.20.00.22.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2020 00:22:49 -0700 (PDT) From: Jiri Pirko To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, jhs@mojatatu.com, xiyou.wangcong@gmail.com, idosch@mellanox.com, mlxsw@mellanox.com Subject: [patch net-next] sched: sch_api: add missing rcu read lock to silence the warning Date: Mon, 20 Jul 2020 09:22:48 +0200 Message-Id: <20200720072248.6184-1-jiri@resnulli.us> X-Mailer: git-send-email 2.21.3 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Jiri Pirko In case the qdisc_match_from_root function() is called from non-rcu path with rtnl mutex held, a suspiciout rcu usage warning appears: [ 241.504354] ============================= [ 241.504358] WARNING: suspicious RCU usage [ 241.504366] 5.8.0-rc4-custom-01521-g72a7c7d549c3 #32 Not tainted [ 241.504370] ----------------------------- [ 241.504378] net/sched/sch_api.c:270 RCU-list traversed in non-reader section!! [ 241.504382] other info that might help us debug this: [ 241.504388] rcu_scheduler_active = 2, debug_locks = 1 [ 241.504394] 1 lock held by tc/1391: [ 241.504398] #0: ffffffff85a27850 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x49a/0xbd0 [ 241.504431] stack backtrace: [ 241.504440] CPU: 0 PID: 1391 Comm: tc Not tainted 5.8.0-rc4-custom-01521-g72a7c7d549c3 #32 [ 241.504446] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014 [ 241.504453] Call Trace: [ 241.504465] dump_stack+0x100/0x184 [ 241.504482] lockdep_rcu_suspicious+0x153/0x15d [ 241.504499] qdisc_match_from_root+0x293/0x350 Fix this by taking the rcu_lock for qdisc_hash iteration. Reported-by: Ido Schimmel Signed-off-by: Jiri Pirko --- net/sched/sch_api.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index 11ebba60da3b..c7cfd8dc6a77 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -267,10 +267,12 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle) root->handle == handle) return root; + rcu_read_lock(); hash_for_each_possible_rcu(qdisc_dev(root)->qdisc_hash, q, hash, handle) { if (q->handle == handle) return q; } + rcu_read_unlock(); return NULL; }