From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=195.10.208.42 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794495989; b=CT9xduHh4CbqfNMsnQeHWnpny0NH5QMo2f3KSY96BnQBQxVwPA2zdu7YhF3GtC0UHs6g OEhm0BwH1RwvA1IrTWvnpvjVjDVxQvmQUGh00/UTrfSYhzdOFn5zRPLkLdg7UrPyioBbP E7j1OyrNdHQt8Y3rkhr5H2fw/rpZQBLc2VPtbr0bMh8Dn7ZpDJJ29FUIum54Hhj0kN/bG ciwaQ0OjcgEcrqDWF8RpdW/EMupIj3cyWX7cyH2aIA5BObjHSHRB/voL+1obzQf6Fh7m2 tyA5X2qb1+hjNPDr9T9oEMV8TXqgJdlOiMgkSJhdjPJTFMIrbeDikH7VNBJjAqrbacQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794495989; h=DMARC-Filter:Received:DKIM-Signature:From:To:Cc:Subject:Date: Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-Rspamd-Queue-Id; bh=95BXVUjFXeYf/sH6PjXF/vGeySat62hqJ4TRbbkb8/c=; b=sdw5s7vVs4tyJqrh+HGSmQnEODuBRkqu2qZpvrSQD3lQedVnXb85Z2VEvLLh0Cvbf4h6 Phoa+ZvSvMdDUKjT230hytKuMIVJEKEdwvAS7WH7NHdwn4MfnE5lxTvyUEXdbxVd6eUSx P5nSLciBlmbEi9//FDS6yar+jiDJYgxuqtlWV2eQ+5xYgeeDEvKo5qg8yHRnDxf2853pf iYrm59YEOWPNHa/xvXBk3BFmEEDiD+mjqGOo665AzK6jXCinxoWDEL4gOs1Z2+8DkoYmD HkSusth1vKP23d/uCijnYfX/z55iAxY/lipDCw2guQFrnyri+AuaKU5QNj0sMKYvapQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=mandelbit.com; spf=pass smtp.mailfrom=mandelbit.com; dkim=pass header.d=mandelbit.com header.i=@mandelbit.com header.a=rsa-sha256 header.s=MBO0001 header.b=Fyuo3k8z; arc=none smtp.remote-ip=195.10.208.42 Received: from mout-b-112.mailbox.org (mout-b-112.mailbox.org [195.10.208.42]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5EA68606A335; Thu, 12 Nov 2026 15:06:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 5EA68606A335 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=mandelbit.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mandelbit.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=mandelbit.com header.i=@mandelbit.com header.a=rsa-sha256 header.s=MBO0001 header.b=Fyuo3k8z Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519MLKEM768 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-b-112.mailbox.org (Postfix) with ESMTPS id 4jQNy45Qbhz5vbs; Thu, 12 Nov 2026 16:06:20 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mandelbit.com; s=MBO0001; t=1794495980; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=95BXVUjFXeYf/sH6PjXF/vGeySat62hqJ4TRbbkb8/c=; b=Fyuo3k8zN40l0/XYRMvaRJKSoUOaimKbCF6FjxYfpz/SUKRA/AblMHr0w121zSKpv3b1A2 gUiM5CFgv1JcF88VU3ox3bcrRPJGf84hOFAsYtEOWUT+lljdONbg2iv9l/vrnwvwhpuMoR 7yWGZnTnGBPAqjelnXxyIzFk8FJirnFheywdR4/F6YAhVIzt/4ZKiNUHDOno9N8rFHnwnf 0NXn1qw4kl35yCNEjGACjC1HCUpnEDRye/mY1uTvEr3nc+DYiBAq+H091DdLPVO28QI1kx GhAhGXNaoO+Ebej/YjT+ZJWCxZPqg/MvhDCfg/iK67r9hXzkMzB6lo4CWZv/qw== Authentication-Results: outgoing_mbo_mout; dkim=none; spf=pass (outgoing_mbo_mout: domain of antonio@mandelbit.com designates 2001:67c:2050:b231:465::1 as permitted sender) smtp.mailfrom=antonio@mandelbit.com From: Antonio Quartulli To: willemdebruijn.kernel@gmail.com, jasowangio@gmail.com Cc: Antonio Quartulli , andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH net-next 3/3] tun: skip the virtio-net header parsing without IFF_VNET_HDR Date: Thu, 12 Nov 2026 16:06:05 +0100 Message-ID: <20261112150612.3866546-4-antonio@mandelbit.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261112150612.3866546-1-antonio@mandelbit.com> References: <20261112150612.3866546-1-antonio@mandelbit.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4jQNy45Qbhz5vbs Without IFF_VNET_HDR, tun_get_user() still passes an all-zero header to tun_vnet_hdr_tnl_to_skb(), which then only resets the MAC header. Do just that. -1.6% instructions per 1400-byte packet dropped at the raw table, -2.2% when written 64 per write() (emulated x86). Signed-off-by: Antonio Quartulli --- drivers/net/tun.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 395923651f31..38f9da1ab462 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1943,7 +1943,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, break; } - if (tun_vnet_hdr_tnl_to_skb(tun->flags, features, skb, &hdr)) { + if (!(tun->flags & IFF_VNET_HDR)) { + /* all a zeroed header would do */ + skb_reset_mac_header(skb); + } else if (tun_vnet_hdr_tnl_to_skb(tun->flags, features, skb, &hdr)) { atomic_long_inc(&tun->rx_frame_errors); err = -EINVAL; goto free_skb; -- 2.56.0