From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f201.google.com (mail-qk1-f201.google.com [209.85.222.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E4EC933C187 for ; Fri, 10 Apr 2026 18:23:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775845399; cv=none; b=pqBURvLTteAAW2a+Mkw83HwmQ5+Plk5LEGZctJCFNM2ix67qOYE3/V6k/UvuAQc6SylCjvfT00CBAcLTyWvjMEsQYgi+p4AMu5ZbfbHn7f5pchR4R35iIsgiZeniGnG97Sa9cGCKEoF2z3GYXFRs+7yflfpJmTl2/FacEY2c01A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775845399; c=relaxed/simple; bh=1V3vqvi/JBOLyCskOpWmHzYqj/ULhNcAebQht7m3ogE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=anY/8UBgJd+dc3jU44aiCIGVT+tuJ+ORborU8FmI+bg5SNJYJmwLjuDIxnXp9Ac4D0O4JSvQ2xNbq72aQlx8nR1DiAGTxuxPdblDikkcd/LztlBQxnwH43m5Rm/oMoqMvvEBzBAk+SZd7wuM3w2o22rmJOV+7WXiUo0cTKz8LGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=dkEFlUTw; arc=none smtp.client-ip=209.85.222.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dkEFlUTw" Received: by mail-qk1-f201.google.com with SMTP id af79cd13be357-8d4c2906fdfso251652285a.2 for ; Fri, 10 Apr 2026 11:23:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1775845397; x=1776450197; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GTI7yAOZ81X1QYzsQpHkzfNkmBAzrCB/2s80AeMaadQ=; b=dkEFlUTwaPgVRHC/p87MauYAy9hnB1CQqj0fpTZG5dssLIFY8S5uGiKxEPoWfRxKGR vfnBy2V3bkmqyftNGgYUJvS2A/DlmHnlUaWv6GLwtngcUMyTxoMu3E1QBDp9JZRGmkyO lfoKSfRFuqeaMmDfoQi/kWOFIp9tmaY3SmUGqgrtVwXdSgdXp4HOnp+X9ru4IeP3tO8Y 7JNyPvbUYbIQ70NAzEglx7yEr8f+BeL0WcyPzapphUhFReuGa2DTm6knJWqeZR3AC+Q6 lyOuyedrc1ZDlXv8ogyMrWsuzTrUpkBk9Bk6zIqW27ei1lF7+wpM/M2XSw8vIUlN//bQ x5JQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775845397; x=1776450197; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=GTI7yAOZ81X1QYzsQpHkzfNkmBAzrCB/2s80AeMaadQ=; b=T6/MzD/4tIeJIhC8aNIrvrMtY/BC5XLNaVM761owkkVTW9j2qXUoFATHvOGWlMshay fJU0SiYnruVv7prbMFgPRez+ppFH1UEMzyTMww7N1ntSgUdOvBd+qjAeisv7ZLdeppe4 GX7iUpT/Xin8/6D4Xs9u6mc7joSG2DpB5RlOJ8pHSD5DDJjXg91ZTWttJuy11AQooGO5 zWnMoz6VWKvkBQNtFlVzQiLUXbPztCLbaIVm5Hw96ixxSTPCIK1TKM+BNeXj8PSm4ac2 UAdFGSdwkJEBFb7u+9etJTs6uK/t4Ola1nsrH+AOY0erJm8qYWdXVgivocWevPovA3YT zyFQ== X-Forwarded-Encrypted: i=1; AJvYcCWix735uv1IVrcjY5S0jhPG8AVTtGOd44Dz5qZ4aId4JpWOIHrSGKHGwy+HHOQlwsPS59awaOI=@vger.kernel.org X-Gm-Message-State: AOJu0Yyfi0OooKXqGTasP7VyMBYQf1mCRW7qKLvvx5WVD7mEKLogQqdH b0Q67jMysylRi9aHxNprfGTlTfmv/keFfM6iGqpCsSKe9MEeR0/NeUULFoWuVnXxUC0B0zG0LsY zrgV6BIPGL7m7PA== X-Received: from qkbg18.prod.google.com ([2002:a05:620a:a352:b0:8d4:dc72:da52]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:3705:b0:8dd:7422:6934 with SMTP id af79cd13be357-8ddcfea0d0amr633131185a.44.1775845396596; Fri, 10 Apr 2026 11:23:16 -0700 (PDT) Date: Fri, 10 Apr 2026 18:22:49 +0000 In-Reply-To: <20260410182257.774311-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260410182257.774311-1-edumazet@google.com> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260410182257.774311-8-edumazet@google.com> Subject: [PATCH v3 net-next 07/15] net/sched: sch_red: annotate data-races in red_dump_stats() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Jamal Hadi Salim , Jiri Pirko , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" 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 --- 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 7db97c96351309bc3e64fa50570a1928f2b2ce55..268f1ba4520cd74da60e7b1ca08974fcfdced680 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 = QDISC_DROP_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, qstats_backlog_add(sch, len); qdisc_qlen_inc(sch); } 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)); } -- 2.53.0.1213.gd9a14994de-goog