From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 80B2D1C5D5E; Thu, 29 Jan 2026 23:54:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769730888; cv=none; b=n9yK959KjseQ9O7SuXMDdREuwuSGP4TF5KzNTXPC8HsmdHtXUIDyoZsVKm1wN6wChftVaV68hHk0QGlczlG44MZbSNJ/s4fTJI67tNjIcTHmJLbM1tKAU0cb42ApfDMfwOzgzhFQHuDy5PnI/Hya1arZNmQ7r11jZp0MkOenuuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769730888; c=relaxed/simple; bh=IH4KZ4/IHTiqZnYNO5l+RgXhtcuGPAcrBHmuecttj9I=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=HJALB/9VAKxS4MJXc6WRi+K8v45Yqb3eS5LJD0k2roGbIxk94DnYipODee8IWJKme/a1XLaDf6svOA4Umuj03A8ocqqXhUqFDOiOi7wtulcdwaxChphXr7CrnOCFy/DZ5gpHFwx7UHQqTYKiAkyXeYSbk2y6rJPNefJacCxGyjk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RbIRht2z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RbIRht2z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 073B7C4CEF7; Thu, 29 Jan 2026 23:54:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769730888; bh=IH4KZ4/IHTiqZnYNO5l+RgXhtcuGPAcrBHmuecttj9I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RbIRht2zOmglKM95qYpF5gN9+0Ch5YImdhKoD6XuuPr3QAq+LhTlWc46pnSWkw0r9 goC3XYpamMTukJIOPDD68xx7nh8jekRTT44JmxDuDOoTZjo5TI8pRiC7jNZu6N58wy B/m0igaFhNGYmUZgAhjMQjB77nhxVdWOj/TW0XRbgGfGEwHiAOf8mwBaw7K46svLJf zIAA/jVj6Vev4leoHVZrIAzaiDq+Ht1lntkGhUlfUCmNIiarnZuaFJWVpMJ5FsJH67 ux5ZB4Sok1htI1umkqRnsnp88nWjgYyjdmbAjvYHnDgV3aeNZNPwlLimBKksVdXXCK /UxsIKSOIae8w== Date: Thu, 29 Jan 2026 15:54:46 -0800 From: Jakub Kicinski To: Gal Pressman Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, dsahern@gmail.com, bpf@vger.kernel.org Subject: Re: [PATCH net] net: don't touch dev->stats in BPF redirect paths Message-ID: <20260129155446.4ad21f1e@kernel.org> In-Reply-To: <9dfdd7ce-ad1c-4845-95ee-d8ac5b5802e7@nvidia.com> References: <20260128161030.39870-1-kuba@kernel.org> <9dfdd7ce-ad1c-4845-95ee-d8ac5b5802e7@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 29 Jan 2026 09:45:10 +0200 Gal Pressman wrote: > 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 > > 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 > > Aha, this kinda makes my mlx5 fix redundant. > I'm debating whether I should send a revert? Up to you, it doesn't hurt. I guess the main reason to revert would be to catch similar bugs in the future, given the popularity of mlx5, but up to you if you want to be exposed to such bugs :) > > 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. Fair, let me respin with a note.