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 53737C4167B for ; Mon, 27 Nov 2023 12:10:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233106AbjK0MJ5 (ORCPT ); Mon, 27 Nov 2023 07:09:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233052AbjK0MJz (ORCPT ); Mon, 27 Nov 2023 07:09:55 -0500 Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BCFBC3 for ; Mon, 27 Nov 2023 04:10:02 -0800 (PST) Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-5c17cff57f9so4032642a12.0 for ; Mon, 27 Nov 2023 04:10:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701087001; x=1701691801; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1P4PRUi9Xdta33xqdQzdIrLH/q/bDppjD9WobOhqYa0=; b=GnG22Va2y5abLWSrMOWd6zAmhW1IKa10ohcPsxE15A8mh827DiWb+06zIxpcAw0Q/e 0kuK/ngdNIgyWWLTzQ03jpvkAQhRrQ74ATWPgG/cptJIR62SPrrGAslL3aJLlNhd2V7R Ne5rY3OBjLhwZRHOziznuF+DMHH5Su4yXQmVkmsSyQ5AO4/8Lmd5EtOp5MmOMJjAxhxw 6ja9TnDHjx/6a6STn+19UvGw9/pvgZw08WxoQGu9p9r7z6NnaGh6xTTeotWd9O9698d3 2dN01E+oeqxJCBYTwJ5LPlnBxMulmTHd8A+Ox8f+jHylIiWakvQMGY+ktCpLerDtTt0E iqwg== X-Gm-Message-State: AOJu0YycyfDj5P9pgj85iLxoEFP68edCxUXdN5Xx5AdXxMg8F/WUixKx 9Nyw9RlxRMswSPQvf14s7S3bF0X5VeBBJ16hFnUtLdBbjYshrJM= X-Google-Smtp-Source: AGHT+IGKY2LVJDt7eef1Z2ctBXK60gaNxOtvZgwaL2MRd74GTITxloGEpiGtmt1nw+k8fmc6fnokqeBVDL8Tv2BCi7/Ejrv1HwTD MIME-Version: 1.0 X-Received: by 2002:a63:d12:0:b0:5b8:eaa4:c6d8 with SMTP id c18-20020a630d12000000b005b8eaa4c6d8mr1854981pgl.1.1701087001018; Mon, 27 Nov 2023 04:10:01 -0800 (PST) Date: Mon, 27 Nov 2023 04:10:00 -0800 In-Reply-To: <000000000000f2771905a46374fe@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <0000000000006d859a060b212e83@google.com> Subject: Re: [syzbot] [net?] possible deadlock in sch_direct_xmit From: syzbot To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org. *** Subject: [net?] possible deadlock in sch_direct_xmit Author: eadavis@qq.com please test deadlock in sch_direct_xmit #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 4195a4bc26ca..9e418f94757d 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -337,13 +337,16 @@ bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, #endif if (likely(skb)) { - HARD_TX_LOCK(dev, txq, smp_processor_id()); - if (!netif_xmit_frozen_or_stopped(txq)) - skb = dev_hard_start_xmit(skb, dev, txq, &ret); - else - qdisc_maybe_clear_missed(q, txq); + int cpu = smp_processor_id(); + if (READ_ONCE(txq->xmit_lock_owner) != cpu) { + HARD_TX_LOCK(dev, txq, cpu); + if (!netif_xmit_frozen_or_stopped(txq)) + skb = dev_hard_start_xmit(skb, dev, txq, &ret); + else + qdisc_maybe_clear_missed(q, txq); - HARD_TX_UNLOCK(dev, txq); + HARD_TX_UNLOCK(dev, txq); + } } else { if (root_lock) spin_lock(root_lock);