netdev - [PATCH net] net: don't touch dev->stats in BPF redirect paths

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Message-ID: <20260128161030.39870-1-kuba@kernel.org>
Date: Wed, 28 Jan 2026 08:10:30 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	Jakub Kicinski <kuba@...nel.org>,
	Gal Pressman <gal@...dia.com>,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	dsahern@...il.com,
	bpf@...r.kernel.org
Subject: [PATCH net] net: don't touch dev->stats in BPF redirect paths

Gal reports that BPF redirect increments dev->stats.tx_errors
on failure. This is not correct, most modern drivers completely
ignore dev->stats so these drops will be invisible to the user.
Core code should use the dedicated core stats which are folded
into device stats in dev_get_stats().

Reported-by: Gal Pressman <gal@...dia.com>
Link: https://lore.kernel.org/c5df3b60-246a-4030-9c9a-0a35cd1ca924@nvidia.com
Fixes: b4ab31414970 ("bpf: Add redirect_neigh helper as redirect drop-in")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: ast@...nel.org
CC: daniel@...earbox.net
CC: andrii@...nel.org
CC: martin.lau@...ux.dev
CC: eddyz87@...il.com
CC: song@...nel.org
CC: yonghong.song@...ux.dev
CC: john.fastabend@...il.com
CC: kpsingh@...nel.org
CC: sdf@...ichev.me
CC: haoluo@...gle.com
CC: jolsa@...nel.org
CC: dsahern@...il.com
CC: bpf@...r.kernel.org
---
 net/core/filter.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 616e0520a0bb..2c21735798a5 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2289,12 +2289,12 @@ static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev,
 
 	err = bpf_out_neigh_v6(net, skb, dev, nh);
 	if (unlikely(net_xmit_eval(err)))
-		DEV_STATS_INC(dev, tx_errors);
+		dev_core_stats_tx_dropped_inc(dev);
 	else
 		ret = NET_XMIT_SUCCESS;
 	goto out_xmit;
 out_drop:
-	DEV_STATS_INC(dev, tx_errors);
+	dev_core_stats_tx_dropped_inc(dev);
 	kfree_skb(skb);
 out_xmit:
 	return ret;
@@ -2396,12 +2396,12 @@ static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev,
 
 	err = bpf_out_neigh_v4(net, skb, dev, nh);
 	if (unlikely(net_xmit_eval(err)))
-		DEV_STATS_INC(dev, tx_errors);
+		dev_core_stats_tx_dropped_inc(dev);
 	else
 		ret = NET_XMIT_SUCCESS;
 	goto out_xmit;
 out_drop:
-	DEV_STATS_INC(dev, tx_errors);
+	dev_core_stats_tx_dropped_inc(dev);
 	kfree_skb(skb);
 out_xmit:
 	return ret;
-- 
2.52.0