From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f202.google.com (mail-qt1-f202.google.com [209.85.160.202]) (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 866C23C73DE for ; Wed, 8 Apr 2026 12:56:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775652988; cv=none; b=mcbDWA4OTayhqgU2naGrLStg6ocL+Yx0nfRvLbCB8BYfB2ezFniRrBX31MtMzF4x+NunJqexDtBc9w3BcnsGFYN+d9m1cXo+cB9osEeXFZ1mhDlXDd8SIU0MS0PcHTnVGjxz7aq6gedLv6r51aeGmvIblQBsKFlqAthItnScI+Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775652988; c=relaxed/simple; bh=1V3vqvi/JBOLyCskOpWmHzYqj/ULhNcAebQht7m3ogE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=gJYWtathiC5U+2ZIjD8g5O7bedPvsqzjtnvJy9d47hs2CJTja6eikfJrDcfNxXL/LgJCfO8q2N+iADb382sQTB9OKQe+k5bpO33Lkx0f/FZq2GI/qUskMiXXhA/Mpa96TdNRDvF2tU7rVflSk2QXIwNv+uApMa/hOKyahzLUuak= 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=F0P846hN; arc=none smtp.client-ip=209.85.160.202 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="F0P846hN" Received: by mail-qt1-f202.google.com with SMTP id d75a77b69052e-50d9a6a853bso69548361cf.0 for ; Wed, 08 Apr 2026 05:56:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1775652986; x=1776257786; 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=F0P846hNJPh3Cvzz0txNbTDn8/SBWcFWRr5WCrasP2Xqs8fNVW+TvH2JT2ArNy0Al9 2BFMnyymPPFt5l5nWJ31c2XKKsE2HZqy9cix8CMBZKrCHNqd5ymsKqC48r8HHwOubgtE 91Zql7hq6vJEFznMNWMVwntTGgDpQ3/Tmeecb8Li3wxnCiogTBaomiN43ps2oNFVVVSd nkodUTGTno3lCQzT6HDtzkwS6cCZf9++UET08WvOvbRDzUeP8Pp0G6FWft8wACDJJP7m gaAHdV15Gvq28c6taQqCTjbtqawWpvohg/4WSwKYAwPcd8tEgOszWDfUl0x8EWtJhdGC CDww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775652986; x=1776257786; 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=HxuKmUt5pERq69LdCewr8ft0iayuPyq+RsMHc76uwX+r2RaqzkaDqBri3IQntrubnY 8GymyBrSQXIQCl8uKrRbhyKmym+yi3O94P1wmaQxq99NWwhLlheUgCJc+Cv6+lwOIfje TL+fSJcWb76w+9+YBx9w0hEC/6TZFS79C4b8lLHkGr0hdZVgEA74CBDqvxY1a1foG86W akdM5gfrVfkVm0itHa5yDXNT5i6268QRtOsKN+jzFSHaVH2Cmwsj/nvkmEOGq2KPiPRS 9D+DAkFi47IaT1n05SvP8tZrMZ1OR2aQ2EauMhG2j9WVBvU5BLF/mNmNL6Uta1/QXwFb GdtQ== X-Forwarded-Encrypted: i=1; AJvYcCVhSMR027od57+GsCAEpCsR2QiIFUirQ5zdaZB5J7kgq6v0V+MYWTcUW5L8/3qnmMmvdRYml2M=@vger.kernel.org X-Gm-Message-State: AOJu0YzFh4cs90mq9lQ9hGMxGEeH4R9NOHc9QM19wjmfEv4FhDvmj1cN OD9LQya7GByWoCaWsPcqQk0/e97uMRTT9DXQP+flA0W0nMFpCYKMP+PledsgZt7gcG+mDUJO8Nf raMq2kS94Yuz/Cg== X-Received: from qtns1.prod.google.com ([2002:ac8:5281:0:b0:509:5140:c6c1]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:622a:684d:10b0:509:1a36:6ad9 with SMTP id d75a77b69052e-50d629c3819mr239515931cf.30.1775652986375; Wed, 08 Apr 2026 05:56:26 -0700 (PDT) Date: Wed, 8 Apr 2026 12:56:03 +0000 In-Reply-To: <20260408125611.3592751-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260408125611.3592751-1-edumazet@google.com> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260408125611.3592751-8-edumazet@google.com> Subject: [PATCH 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