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 E13D01B87C0; Sat, 30 May 2026 18:44:59 +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=1780166701; cv=none; b=Tjr+q3rK/0+LhlRQE0KiagvxbSrGI7cUOzrx/QLWY0bQRkeL2gEkHAdFj8C7prqNqQfVnA5FUSuFgWX3z+3ugyGRDBOErig6USFpAIEDYTmqk+Wcw+KemP9bhOnQJ51+Ykc5e3MT4/A8DGZ9Gi//999RTT+1JkTvoVXT8cYrWc4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780166701; c=relaxed/simple; bh=W9auTEGNcnGf+tPkSlS3+LKd7zsH2nviVKhXUZ72szg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aPKnzD+hH+U1YZwhvQLZiULfX0vI10VNCepCe144UTQEinQMBZwKpev+iFhI4SuLKaZA1J3Syi4Mbs4q/qdRQiVglvaBjpP7ExRqnA+tJHTN00X9g5vbzKbEHcnpWh0qk7KHbPJEL0Z5FnGUDDEUW69dKPqzEpSaCTcX2EDL9CE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Xrv3QHkJ; 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="Xrv3QHkJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 012E11F00893; Sat, 30 May 2026 18:44:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780166699; bh=RTPJfjCSpGUlGxpSxDqbp03bgB4r00enF25lSLRQqKU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Xrv3QHkJslbrEXBX4OvcYUIhw+kMsM3NtHlNKyWZZ3njqbmAIRX/kNjyFRoqdiY8M wdx4tjrgae5A4NPHuABi3oSZf48zve2Usz6HN1rhOdOOj0EcQVQfbFT+W86zGlCSno 55ZxmPd4a4Cxzm8bZzLx7ozXgh+D1mPE6rsAHeXQ= 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 5.10 445/589] net/sched: sch_pie: annotate data-races in pie_dump_stats() Date: Sat, 30 May 2026 18:05:26 +0200 Message-ID: <20260530160236.396102935@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160224.570625122@linuxfoundation.org> References: <20260530160224.570625122@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 5154561d9b119f781249f8e845fecf059b38b483 ] pie_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_pie_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/20260421142944.4009941-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/pie.h | 2 +- net/sched/sch_pie.c | 38 +++++++++++++++++++------------------- 2 files changed, 20 insertions(+), 20 deletions(-) diff --git a/include/net/pie.h b/include/net/pie.h index 3fe2361e03b46..f6fd51e2b7daa 100644 --- a/include/net/pie.h +++ b/include/net/pie.h @@ -104,7 +104,7 @@ static inline void pie_vars_init(struct pie_vars *vars) vars->dq_tstamp = DTIME_INVALID; vars->accu_prob = 0; vars->dq_count = DQCOUNT_INVALID; - vars->avg_dq_rate = 0; + WRITE_ONCE(vars->avg_dq_rate, 0); } static inline struct pie_skb_cb *get_pie_cb(const struct sk_buff *skb) diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c index 47f5d4adb5a33..7a8b05174ebf7 100644 --- a/net/sched/sch_pie.c +++ b/net/sched/sch_pie.c @@ -89,7 +89,7 @@ static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, bool enqueue = false; if (unlikely(qdisc_qlen(sch) >= sch->limit)) { - q->stats.overlimit++; + WRITE_ONCE(q->stats.overlimit, q->stats.overlimit + 1); goto out; } @@ -101,7 +101,7 @@ static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, /* If packet is ecn capable, mark it if drop probability * is lower than 10%, else drop it. */ - q->stats.ecn_mark++; + WRITE_ONCE(q->stats.ecn_mark, q->stats.ecn_mark + 1); enqueue = true; } @@ -111,15 +111,15 @@ static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, if (!q->params.dq_rate_estimator) pie_set_enqueue_time(skb); - q->stats.packets_in++; + WRITE_ONCE(q->stats.packets_in, q->stats.packets_in + 1); if (qdisc_qlen(sch) > q->stats.maxq) - q->stats.maxq = qdisc_qlen(sch); + WRITE_ONCE(q->stats.maxq, qdisc_qlen(sch)); return qdisc_enqueue_tail(skb, sch); } out: - q->stats.dropped++; + WRITE_ONCE(q->stats.dropped, q->stats.dropped + 1); q->vars.accu_prob = 0; return qdisc_drop(skb, sch, to_free); } @@ -263,11 +263,11 @@ void pie_process_dequeue(struct sk_buff *skb, struct pie_params *params, count = count / dtime; if (vars->avg_dq_rate == 0) - vars->avg_dq_rate = count; + WRITE_ONCE(vars->avg_dq_rate, count); else - vars->avg_dq_rate = + WRITE_ONCE(vars->avg_dq_rate, (vars->avg_dq_rate - - (vars->avg_dq_rate >> 3)) + (count >> 3); + (vars->avg_dq_rate >> 3)) + (count >> 3)); /* If the queue has receded below the threshold, we hold * on to the last drain rate calculated, else we reset @@ -377,7 +377,7 @@ void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars, if (delta > 0) { /* prevent overflow */ if (vars->prob < oldprob) { - vars->prob = MAX_PROB; + WRITE_ONCE(vars->prob, MAX_PROB); /* Prevent normalization error. If probability is at * maximum value already, we normalize it here, and * skip the check to do a non-linear drop in the next @@ -388,7 +388,7 @@ void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars, } else { /* prevent underflow */ if (vars->prob > oldprob) - vars->prob = 0; + WRITE_ONCE(vars->prob, 0); } /* Non-linear drop in probability: Reduce drop probability quickly if @@ -399,7 +399,7 @@ void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars, /* Reduce drop probability to 98.4% */ vars->prob -= vars->prob / 64; - vars->qdelay = qdelay; + WRITE_ONCE(vars->qdelay, qdelay); vars->backlog_old = backlog; /* We restart the measurement cycle if the following conditions are met @@ -494,21 +494,21 @@ static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d) struct pie_sched_data *q = qdisc_priv(sch); struct tc_pie_xstats st = { .prob = q->vars.prob << BITS_PER_BYTE, - .delay = ((u32)PSCHED_TICKS2NS(q->vars.qdelay)) / + .delay = ((u32)PSCHED_TICKS2NS(READ_ONCE(q->vars.qdelay))) / NSEC_PER_USEC, - .packets_in = q->stats.packets_in, - .overlimit = q->stats.overlimit, - .maxq = q->stats.maxq, - .dropped = q->stats.dropped, - .ecn_mark = q->stats.ecn_mark, + .packets_in = READ_ONCE(q->stats.packets_in), + .overlimit = READ_ONCE(q->stats.overlimit), + .maxq = READ_ONCE(q->stats.maxq), + .dropped = READ_ONCE(q->stats.dropped), + .ecn_mark = READ_ONCE(q->stats.ecn_mark), }; /* avg_dq_rate is only valid if dq_rate_estimator is enabled */ st.dq_rate_estimating = q->params.dq_rate_estimator; /* unscale and return dq_rate in bytes per sec */ - if (q->params.dq_rate_estimator) - st.avg_dq_rate = q->vars.avg_dq_rate * + if (st.dq_rate_estimating) + st.avg_dq_rate = READ_ONCE(q->vars.avg_dq_rate) * (PSCHED_TICKS_PER_SEC) >> PIE_SCALE; return gnet_stats_copy_app(d, &st, sizeof(st)); -- 2.53.0