From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 76B17217F34; Thu, 12 Dec 2024 15:31:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734017475; cv=none; b=M+Wx+0QJ+s8xgXF0XoXAujBFhrd+1NS5yLn2jo5V+P4wVGNzG7ltfvSDp9Qmz117UnjuiIc+vrvleA/EeZ/drN0kvNwRv4qF6YJ2/S9C5wgWsLBWccV83KJNNeplAO+wSZ23ZXZx/53dOE4ZatLTHrHQmtWiXyXT2Us1sqXG+xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734017475; c=relaxed/simple; bh=V4HC51sRP83m/66ys09pi2mGltXkxg9u9Z4y2zSB2ew=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fI1SNRMvi1grxCm0O5kAlNyA8P2PHYlWEIOqwOlMOhX+s9SK14kAd8OMhKwOmJvqahNArd4nysJK9p+cx0yzjOk8qFwrtCfei2jg5ct4f5EIsfZhDutVUqmt+5/n+laJtxWMjEGo24TwS11GMMpWUFsRHFs33d/yoo204HC1Mjk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WEeaWlfN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WEeaWlfN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC4B5C4CECE; Thu, 12 Dec 2024 15:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734017475; bh=V4HC51sRP83m/66ys09pi2mGltXkxg9u9Z4y2zSB2ew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WEeaWlfN+Gf9gwI+Z4nXcZGxh93tdTUE3QoCH43/SYGjMYy0fdq49VKE4qbcPaeCC 7OuX8la/W9mMf6+B6sMK/dDm75gLffWw1ZwVigazWK4uHvMszj74hcFoG81z7RjWQb EebPdjSGtVhsoH2alBIABMLsbb1N1G9qUGo9vTZM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin Ottens , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 023/356] net/sched: tbf: correct backlog statistic for GSO packets Date: Thu, 12 Dec 2024 15:55:42 +0100 Message-ID: <20241212144245.535055684@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144244.601729511@linuxfoundation.org> References: <20241212144244.601729511@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Ottens [ Upstream commit 1596a135e3180c92e42dd1fbcad321f4fb3e3b17 ] When the length of a GSO packet in the tbf qdisc is larger than the burst size configured the packet will be segmented by the tbf_segment function. Whenever this function is used to enqueue SKBs, the backlog statistic of the tbf is not increased correctly. This can lead to underflows of the 'backlog' byte-statistic value when these packets are dequeued from tbf. Reproduce the bug: Ensure that the sender machine has GSO enabled. Configured the tbf on the outgoing interface of the machine as follows (burstsize = 1 MTU): $ tc qdisc add dev root handle 1: tbf rate 50Mbit burst 1514 latency 50ms Send bulk TCP traffic out via this interface, e.g., by running an iPerf3 client on this machine. Check the qdisc statistics: $ tc -s qdisc show dev The 'backlog' byte-statistic has incorrect values while traffic is transferred, e.g., high values due to u32 underflows. When the transfer is stopped, the value is != 0, which should never happen. This patch fixes this bug by updating the statistics correctly, even if single SKBs of a GSO SKB cannot be enqueued. Fixes: e43ac79a4bc6 ("sch_tbf: segment too big GSO packets") Signed-off-by: Martin Ottens Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20241125174608.1484356-1-martin.ottens@fau.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_tbf.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c index 17d2d00ddb182..f92174008499b 100644 --- a/net/sched/sch_tbf.c +++ b/net/sched/sch_tbf.c @@ -208,7 +208,7 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, struct tbf_sched_data *q = qdisc_priv(sch); struct sk_buff *segs, *nskb; netdev_features_t features = netif_skb_features(skb); - unsigned int len = 0, prev_len = qdisc_pkt_len(skb); + unsigned int len = 0, prev_len = qdisc_pkt_len(skb), seg_len; int ret, nb; segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); @@ -219,21 +219,27 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, nb = 0; skb_list_walk_safe(segs, segs, nskb) { skb_mark_not_on_list(segs); - qdisc_skb_cb(segs)->pkt_len = segs->len; - len += segs->len; + seg_len = segs->len; + qdisc_skb_cb(segs)->pkt_len = seg_len; ret = qdisc_enqueue(segs, q->qdisc, to_free); if (ret != NET_XMIT_SUCCESS) { if (net_xmit_drop_count(ret)) qdisc_qstats_drop(sch); } else { nb++; + len += seg_len; } } sch->q.qlen += nb; - if (nb > 1) + sch->qstats.backlog += len; + if (nb > 0) { qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); - consume_skb(skb); - return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; + consume_skb(skb); + return NET_XMIT_SUCCESS; + } + + kfree_skb(skb); + return NET_XMIT_DROP; } static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch, -- 2.43.0