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 1403D358363 for ; Thu, 9 Apr 2026 21:49:30 +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=1775771372; cv=none; b=Ubmno+bNt+ntIvyhB0bPY/j8p3Ff5RyyQFyWTDXHoJ6kgkf+/oZTHw5uCgjt3DKUKjILN7KeIUERomndAY1U0/QZZnCezSWYt1V4rxmVvJ68qBOGwZGjxEhnFXIEZpjXjs6Vd239AYDMhazCszoqPdysOevo5rdgcBhBvpFHnHw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775771372; c=relaxed/simple; bh=1V3vqvi/JBOLyCskOpWmHzYqj/ULhNcAebQht7m3ogE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=dXuN+H9it779UoSMdrytiXIcEbFxLUBlHi/M+Rp+oX5Mu1+cuPFwdjwtGBFWsWmGo9Wg/JY03gjoe4fLXqwqySVJwLpB/ia3GlOqU8SrfhxUQfbxhGajFp2Fybhl0d2LtC9OfsD1/GPxZZJSj6mEp14V3xwfMAgrOZucv6qTisY= 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=Rq98F+io; 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="Rq98F+io" Received: by mail-qk1-f201.google.com with SMTP id af79cd13be357-8d3bea3aa34so301925285a.0 for ; Thu, 09 Apr 2026 14:49:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1775771370; x=1776376170; 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=Rq98F+ioDyKnpbOpOV16l7eX35Xw8+XDziE8O8N2bJCzN87ydbp3xjTNtOTO0MCmzd WcNR/FoePSs3414Oixsw3gJfzcnquXp48rvfLZ8q/KWXGG8fgM0UCFZt6yuMcJTRQHH2 xKlg02M8+OFbA0KeskTw6dH7i56f61XlH5+nz7BsWBg3lTCn7uAp0vnpJt/nFRyG2Aje oNgmsSrxvpaVzjd0hupjpElgViU1z5XF5mN+Dns+8W/ZYx7U8CQQVwSb+BgF6AV8kjWV FYrv0uMKCkIWIusELCbsbwgkbDBK5t+IZ4SWM0BPALnIit+SmfOqIXVldK94pSQn41Bh pWsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775771370; x=1776376170; 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=fFIf60YUFQNkosvcBIPaT7RH1o9qqLd/nGDdZ3gY4cFB/WWVFU2TsLA/HfR9xugww2 XhX45o4w9JDbJx3UKsbNhMCZgWfCnDiXTUhK7VkZXYw5UssSWaYUnnvtAV3UxMR7E3tJ 9atkcDtxvfFP4YGixYfZe9OTafbtz+2wq1/1cF/xbBJEiaeHyWsOvXyMatWB6J2NIiNw kah00em7+9n7xxENzMkG9mo+T7+hf82//3GqnfdY6g0jTIo9xSVwKbU07X7dKlr2KDEU d2a7Wl452h6WznU8BU7EM3agUzk/syQVm6Sd6Zj5EZW70IS5soqHBu7djHGEjgAfIZWz TIXg== X-Forwarded-Encrypted: i=1; AJvYcCUcAeVNBQJaJ7pYOUrC0KxZ6MptQn0SKp9/KmlnMdK6MEfXMg/Lo5rWyZ6iMieG29+jm+HqTA4=@vger.kernel.org X-Gm-Message-State: AOJu0YyROzsHIz+0McEUqzIWY6EEyV3zd662oqGhteQnEq40I6LD41wa GpRfb0uGXFCMFHew0w0omFJJnSbbV1qfY+QNarzqH2l0hDFEaVFpQHteW8RDFo35Tav51HjyljT J/kXwRhya6eC3lg== X-Received: from qkah27.prod.google.com ([2002:a05:620a:21db:b0:8d3:bb62:c8af]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:4443:b0:8cf:cc52:635f with SMTP id af79cd13be357-8ddce2c6f10mr94342685a.29.1775771369720; Thu, 09 Apr 2026 14:49:29 -0700 (PDT) Date: Thu, 9 Apr 2026 21:49:06 +0000 In-Reply-To: <20260409214914.3072827-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260409214914.3072827-1-edumazet@google.com> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260409214914.3072827-8-edumazet@google.com> Subject: [PATCH v2 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 , Kuniyuki Iwashima , 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