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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 C0C6BC433DB for ; Mon, 22 Feb 2021 19:52:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87E3E64DF0 for ; Mon, 22 Feb 2021 19:52:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233363AbhBVTwX (ORCPT ); Mon, 22 Feb 2021 14:52:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51826 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231326AbhBVTwW (ORCPT ); Mon, 22 Feb 2021 14:52:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614023454; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=8HR1V1PEJZUHvsgCjR9y0BSATwd2Ojt2c/7KCE8Moeo=; b=EU3pUp54anGKBdinCEbQbu9Uk8u85AM+5/zIB7Koe+pkfy66RAiEts/fHBXOfJkd+gr0sY hajFV9mytj9VVG9V7oTTnbllAAraK7Cn2+Hdz86XJXrTBA21vlv21xkCNSoWMOZaTz8Ekm 7VIaN0hNLfF7cskYaSA56bqDQDdb5H4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-515-Y57ap3dGOOa8RWp2ZFbkAA-1; Mon, 22 Feb 2021 14:50:50 -0500 X-MC-Unique: Y57ap3dGOOa8RWp2ZFbkAA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E654418A0838; Mon, 22 Feb 2021 19:50:48 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id B33D160C04; Mon, 22 Feb 2021 19:50:45 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 6016F30736C73; Mon, 22 Feb 2021 20:50:44 +0100 (CET) Subject: [PATCH RFC net-next] mlx5: fix for crash on net-next From: Jesper Dangaard Brouer To: Jesper Dangaard Brouer , netdev@vger.kernel.org, Saeed Mahameed Cc: Jakub Kicinski , "David S. Miller" , saeedm@nvidia.com, Tariq Toukan , eranbe@nvidia.com, maximmi@mellanox.com Date: Mon, 22 Feb 2021 20:50:44 +0100 Message-ID: <161402344429.1980160.4798557236979159924.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Net-next at commit d310ec03a34e ("Merge tag 'perf-core-2021-02-17') There is a divide error in drivers/net/ethernet/mellanox/mlx5/core/en_tx.c where it seems that num_tc_x_num_ch can become zero in a modulo operation: if (unlikely(txq_ix >= num_tc_x_num_ch)) txq_ix %= num_tc_x_num_ch; I think error were introduced in: - 214baf22870c ("net/mlx5e: Support HTB offload") The modulo operation was introduced in: - 145e5637d941 ("net/mlx5e: Add TX PTP port object support") The crash looks like this: [ 12.112849] divide error: 0000 [#1] PREEMPT SMP PTI [ 12.117727] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 5.11.0-net-next+ #575 [ 12.124677] Hardware name: Supermicro Super Server/X10SRi-F, BIOS 2.0a 08/01/2016 [ 12.132149] RIP: 0010:mlx5e_select_queue+0xd5/0x1e0 [mlx5_core] [ 12.138110] Code: 85 c0 75 2e 48 83 bb 08 57 00 00 00 75 5b 31 d2 48 89 ee 48 89 df e8 ba 3e 54 e1 0f b7 d0 41 39 d4 0f 8f 6b ff ff ff 89 d0 99 <41> f7 fc e9 60 ff ff ff 8b 96 8c 00 00 00 89 d1 c1 e9 10 39 c1 0f [ 12.156849] RSP: 0018:ffffc900001c0c10 EFLAGS: 00010297 [ 12.162065] RAX: 0000000000000004 RBX: ffff88810ff00000 RCX: 0000000000000007 [ 12.169188] RDX: 0000000000000000 RSI: ffff888107016400 RDI: ffff8881008dc740 [ 12.176313] RBP: ffff888107016400 R08: 0000000000000000 R09: 000000ncing: Fatal exception in interrupt ]--- This is an RFC, because I don't think this is a proper fix, but at least it allows me to boot with mlx5 driver enabled. Signed-off-by: Jesper Dangaard Brouer --- drivers/net/ethernet/mellanox/mlx5/core/en_tx.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c index bdbffe484fce..4dc26c1f2b53 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c @@ -131,6 +131,7 @@ u16 mlx5e_select_queue(struct net_device *dev, struct sk_buff *skb, int ch_ix; /* Sync with mlx5e_update_num_tc_x_num_ch - avoid refetching. */ + // XXX this reading of num_tc_x_num_ch looks strange num_tc_x_num_ch = READ_ONCE(priv->num_tc_x_num_ch); if (unlikely(dev->real_num_tx_queues > num_tc_x_num_ch)) { /* Order maj_id before defcls - pairs with mlx5e_htb_root_add. */ @@ -142,19 +143,21 @@ u16 mlx5e_select_queue(struct net_device *dev, struct sk_buff *skb, return txq_ix; } - if (unlikely(priv->channels.port_ptp)) + txq_ix = netdev_pick_tx(dev, skb, NULL); + + if (unlikely(priv->channels.port_ptp)) { if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && mlx5e_use_ptpsq(skb)) return mlx5e_select_ptpsq(dev, skb); - txq_ix = netdev_pick_tx(dev, skb, NULL); /* Fix netdev_pick_tx() not to choose ptp_channel and HTB txqs. * If they are selected, switch to regular queues. * Driver to select these queues only at mlx5e_select_ptpsq() * and mlx5e_select_htb_queue(). */ - if (unlikely(txq_ix >= num_tc_x_num_ch)) - txq_ix %= num_tc_x_num_ch; + if (unlikely(txq_ix >= num_tc_x_num_ch)) + txq_ix %= num_tc_x_num_ch; + } } else { txq_ix = netdev_pick_tx(dev, skb, NULL); }