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 93979C54EBD for ; Fri, 13 Jan 2023 04:41:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229462AbjAMElr (ORCPT ); Thu, 12 Jan 2023 23:41:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230035AbjAMElp (ORCPT ); Thu, 12 Jan 2023 23:41:45 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5834E6375 for ; Thu, 12 Jan 2023 20:41:43 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 983FACE1FDC for ; Fri, 13 Jan 2023 04:41:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 384BDC433EF; Fri, 13 Jan 2023 04:41:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673584899; bh=1HXG9oCt3sjsMrP6QeAMknr6n1etPS3vLodR1NrRy5Q=; h=From:To:Cc:Subject:Date:From; b=qQXTA6zRzVAKyTsYfwPBFfvAOO9tdqh6HbhhcRTk+e5J2bMeJBPpWX4Hp9grNt5iZ vm/pJvdRMTgHblFjnpeGTeT1mUNTOq1RfXK+ro4WRchqkp5s7BtzxGNyeF4/DbOHeY cmn0pNSIBPu9iBC5qgQv9t7J3o3aUZMdxwk+75XUxXNMP8uqIG+8xxfKcg/b/oKbi9 1z7OxbVH4/pLchDpVt0aJ7orlI2CZTBj4H38laG16m2mmSjNEJuJSvW0iu8lkDEuG0 2bcbU+Lp/gd/s7PENYBpD/2rhdPB0HoR4DaBIUL+B4hYmslYocFXjeMDjSVAcpiFwq BWHfmhJRG6P/g== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, Jakub Kicinski , Linux Kernel Functional Testing , jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, john.hurley@netronome.com Subject: [PATCH net] net: sched: gred: prevent races when adding offloads to stats Date: Thu, 12 Jan 2023 20:41:37 -0800 Message-Id: <20230113044137.1383067-1-kuba@kernel.org> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Naresh reports seeing a warning that gred is calling u64_stats_update_begin() with preemption enabled. Arnd points out it's coming from _bstats_update(). We should be holding the qdisc lock when writing to stats, they are also updated from the datapath. Reported-by: Linux Kernel Functional Testing Link: https://lore.kernel.org/all/CA+G9fYsTr9_r893+62u6UGD3dVaCE-kN9C-Apmb2m=hxjc1Cqg@mail.gmail.com/ Fixes: e49efd5288bd ("net: sched: gred: support reporting stats from offloads") Signed-off-by: Jakub Kicinski --- CC: jhs@mojatatu.com CC: xiyou.wangcong@gmail.com CC: jiri@resnulli.us CC: john.hurley@netronome.com --- net/sched/sch_gred.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c index a661b062cca8..872d127c9db4 100644 --- a/net/sched/sch_gred.c +++ b/net/sched/sch_gred.c @@ -377,6 +377,7 @@ static int gred_offload_dump_stats(struct Qdisc *sch) /* Even if driver returns failure adjust the stats - in case offload * ended but driver still wants to adjust the values. */ + sch_tree_lock(sch); for (i = 0; i < MAX_DPs; i++) { if (!table->tab[i]) continue; @@ -393,6 +394,7 @@ static int gred_offload_dump_stats(struct Qdisc *sch) sch->qstats.overlimits += hw_stats->stats.qstats[i].overlimits; } _bstats_update(&sch->bstats, bytes, packets); + sch_tree_unlock(sch); kfree(hw_stats); return ret; -- 2.38.1