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 346163DA7C6; Wed, 20 May 2026 17:02:31 +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=1779296553; cv=none; b=EvQ7ZppInMyqWIiBGLPrWDQ+Z5WAHFuuKLeJEpNTHsvQl2ltf5nsOoQz66Bw4GHXqxybKL8uUXlfyK30VTyNXFTWoYoNbFIle8CUrcdpAaLFz54SqGw0ysmIKaGiySApZn6nGwUmLLIzSylarv2unrYOVWj5zw3xUWu/pWBP0aw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779296553; c=relaxed/simple; bh=r7RsjlJZTyHPBa7eZ8Z7TpciEWvBfPy/z5xmv4V8EAE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SD5TqdyNTdaLO9rKzS4skPrbh1Hem7ACoZUlDtMDiSj8dmuRM5IPSj9kmatZ9sswJRmUMCXFZJBcYc30mx5eAORYbGBWoASCrTrQWoxewtvgutLMhDhjk5CDrBvoDGShazI3Bdb3w+u1y7Z/3UfTi0x+Nh9Vb58L3VgkSTfkFWo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BieEDwDD; 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="BieEDwDD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 645621F00893; Wed, 20 May 2026 17:02:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779296550; bh=yRn9t95SN8fHaMB8Kv2MYRTggMTYTYK8xgYY3U5MlR0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BieEDwDDykn6igeu3APd5ZrNHUopIDyjvwZyQCKci3ytf9RmKj5L64EsA9uyM4v9M fX2SGmZyRDxADzS2OkM5wiYmawQgU5WxcdKmzzcby9NVVKYrQjy0tD1v5+CuaINuSH NqM3Wt4jeJV7XD5x1jvBgqJDJ5pfwuimomVrLkY4= 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 7.0 0842/1146] net/sched: sch_red: annotate data-races in red_dump_stats() Date: Wed, 20 May 2026 18:18:12 +0200 Message-ID: <20260520162207.290245598@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162148.390695140@linuxfoundation.org> References: <20260520162148.390695140@linuxfoundation.org> User-Agent: quilt/0.69 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 7.0-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 68ee41ce78c50..86651a68d4015 100644 --- a/net/sched/sch_red.c +++ b/net/sched/sch_red.c @@ -90,17 +90,20 @@ 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; } @@ -111,17 +114,20 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch, reason = SKB_DROP_REASON_QDISC_OVERLIMIT; 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; } @@ -135,7 +141,8 @@ 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; @@ -463,9 +470,13 @@ 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