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

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Message-ID: <9dfdd7ce-ad1c-4845-95ee-d8ac5b5802e7@nvidia.com>
Date: Thu, 29 Jan 2026 09:45:10 +0200
From: Gal Pressman <gal@...dia.com>
To: Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net
Cc: netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
 andrew+netdev@...n.ch, horms@...nel.org, 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: Re: [PATCH net] net: don't touch dev->stats in BPF redirect paths

On 28/01/2026 18:10, Jakub Kicinski wrote:
> 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>

Aha, this kinda makes my mlx5 fix redundant.
I'm debating whether I should send a revert?

> 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);

The commit message didn't mention anything about changing tx_errors to
tx_dropped.