From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 87D2F352027; Sat, 30 May 2026 18:10:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780164645; cv=none; b=QFQIlU82VQbpssY58aE5OQzK1KU92BQB9TyTnfwffxzfCJ5uLiTjltt3FcF1u2dGb1kwdH0G7CNCkGTUP5cTl7wTLyO1Tg8sjuwGDSaIily3QeXH65OdHgblFZjcKdpc9/v17QDNVeogH3OeEdlGStMlC0iCwjcnAoh3xnyw0ss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780164645; c=relaxed/simple; bh=jDnKrd+FKa4xWhfX72TlPDptDFSOXtXdBKexppiWew8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SZLZ1yoRrb1AvTGVkM6jGDxo+EHB07/cBPpE+cY/g9NWbTOm+Ez8m03q/ebXBKN0bRfbHehkGEZlSpEZMWFG+X2CctmQn0EMbCFVvb8CwX8mL8JqnvRaHOypyd6WI3p2p+7x7BLnWH4p8itESG+8GvEHdBuiEYSQtOs3h3Kncxc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0KTgIHx4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0KTgIHx4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF3E71F00893; Sat, 30 May 2026 18:10:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780164644; bh=qg7eRIqN3yjeBIIFQvB+5v0Ve4ShtjLgNsh8/lnr0sw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0KTgIHx4Njq1JLIGbU+uaM6ZyNp4Wp+VbOrqI8caRI42zTPuAGJ8Hspo+hjjFKcyE aKaXApXWHibpH36+P9HHG0IOkw6dJ1q8tXkQx01jAePYXWaIX85I7PprQ7sM7f1XsV t9GpIOEClTNpxKBIjMy1vLxWWvoKRPk0hDm+8ZrE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 589/776] net/sched: sch_red: annotate data-races in red_dump_stats() Date: Sat, 30 May 2026 18:05:03 +0200 Message-ID: <20260530160255.285507944@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160240.228940103@linuxfoundation.org> References: <20260530160240.228940103@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit a8f5192809caf636d05ba47c144f282cfd0e3839 ] red_dump_stats() only runs with RTNL held, reading fields that can be changed in qdisc fast path. Add READ_ONCE()/WRITE_ONCE() annotations. Alternative would be to acquire the qdisc spinlock, but our long-term goal is to make qdisc dump operations lockless as much as we can. tc_red_xstats fields don't need to be latched atomically, otherwise this bug would have been caught earlier. Fixes: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump") Signed-off-by: Eric Dumazet Reviewed-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260421142309.3964322-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_red.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c index a2c1db8ac3945..779f8779c762a 100644 --- a/net/sched/sch_red.c +++ b/net/sched/sch_red.c @@ -89,17 +89,20 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, case RED_PROB_MARK: qdisc_qstats_overlimit(sch); if (!red_use_ecn(q)) { - q->stats.prob_drop++; + WRITE_ONCE(q->stats.prob_drop, + q->stats.prob_drop + 1); goto congestion_drop; } if (INET_ECN_set_ce(skb)) { - q->stats.prob_mark++; + WRITE_ONCE(q->stats.prob_mark, + q->stats.prob_mark + 1); skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret); if (!skb) return NET_XMIT_CN | ret; } else if (!red_use_nodrop(q)) { - q->stats.prob_drop++; + WRITE_ONCE(q->stats.prob_drop, + q->stats.prob_drop + 1); goto congestion_drop; } @@ -109,17 +112,20 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, case RED_HARD_MARK: qdisc_qstats_overlimit(sch); if (red_use_harddrop(q) || !red_use_ecn(q)) { - q->stats.forced_drop++; + WRITE_ONCE(q->stats.forced_drop, + q->stats.forced_drop + 1); goto congestion_drop; } if (INET_ECN_set_ce(skb)) { - q->stats.forced_mark++; + WRITE_ONCE(q->stats.forced_mark, + q->stats.forced_mark + 1); skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret); if (!skb) return NET_XMIT_CN | ret; } else if (!red_use_nodrop(q)) { - q->stats.forced_drop++; + WRITE_ONCE(q->stats.forced_drop, + q->stats.forced_drop + 1); goto congestion_drop; } @@ -133,7 +139,8 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, sch->qstats.backlog += len; sch->q.qlen++; } else if (net_xmit_drop_count(ret)) { - q->stats.pdrop++; + WRITE_ONCE(q->stats.pdrop, + q->stats.pdrop + 1); qdisc_qstats_drop(sch); } return ret; @@ -461,9 +468,13 @@ static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &hw_stats_request); } - st.early = q->stats.prob_drop + q->stats.forced_drop; - st.pdrop = q->stats.pdrop; - st.marked = q->stats.prob_mark + q->stats.forced_mark; + st.early = READ_ONCE(q->stats.prob_drop) + + READ_ONCE(q->stats.forced_drop); + + st.pdrop = READ_ONCE(q->stats.pdrop); + + st.marked = READ_ONCE(q->stats.prob_mark) + + READ_ONCE(q->stats.forced_mark); return gnet_stats_copy_app(d, &st, sizeof(st)); } -- 2.53.0