From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 920D34749DD for ; Wed, 7 Oct 2026 10:20:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791368428; cv=none; b=W6s/Ez3+5+q8+liqESdirdWKhUoMZN9ISwl+2cOVmg8iDPNZQahdDO6yGuf/86LAVVQdV/xvAGnR39ZfrCYkKdH92vzvqHzuG1OqqYkmGVNWrygbBMspJvX/yv8Yf1JhlcpC9ecIOKQJbdysyJ+5esI924Fhtj2dTZ62EXMKgWw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791368428; c=relaxed/simple; bh=rFAvUO4Y/vcYHM1X2jKNJMuKbU0DG4p6en3YHWz9DUE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=S7c9gH2kBjrR7IEUQ+6uHDXgPXKatwXuF/0mRM06Gcm5bjygFSZZdaLrxneF2O7RzfgJJa0+pjBwq6p2lq04g2khMCKwz54w1sSslud3r/G7lOlQNpITNVfQpdFPEBt7BozqYTt9Hrz2+xOIsQyY4G+SxBYa4/g/0x7y8VFOZkg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=h8giNJUB; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=Jy9wEEPh; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="h8giNJUB"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="Jy9wEEPh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1791368419; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rFAvUO4Y/vcYHM1X2jKNJMuKbU0DG4p6en3YHWz9DUE=; b=h8giNJUBhVEGNxmVHQEdH54c/XlTcssKwhioOE5d/U1cAyDY4GxPGceWzDr8Ky+3iYD0/5 MOYJspt8dxLVLdZVq78zvm5eCLD9+pqIbfpO826e6jp84ckILBYAbEsBbq1xNORsFUP+Xh QehnUMnGMevch55qTkF86cWZzl+ga7A= Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-607-pJ3JXMq3OsalSzKQlgAJoA-1; Wed, 07 Oct 2026 06:20:18 -0400 X-MC-Unique: pJ3JXMq3OsalSzKQlgAJoA-1 X-Mimecast-MFC-AGG-ID: pJ3JXMq3OsalSzKQlgAJoA_1791368417 Received: by mail-ej1-f70.google.com with SMTP id a640c23a62f3a-c2939083cefso460770766b.1 for ; Wed, 07 Oct 2026 03:20:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1791368417; x=1791973217; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:message-id:date :references:in-reply-to:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=rFAvUO4Y/vcYHM1X2jKNJMuKbU0DG4p6en3YHWz9DUE=; b=Jy9wEEPhwMeUmcZ30M+B2K96pMC9WI6L7uHAEjEAwj0swcHEWs7CK7QdKicyqVvdB4 2V/dF5LfbrEDP1nAOdQOLQxAaAHd9b9G3DzSa8FzjxpGVM59No+cHmbfvYSAkZoFh69k XzTe8K6y6fns9egJyTOUn+9FSDUfgVWWymeF6tXJIZi5VhWfSPYvunB1GJux7+1wGgKS QccKXwWqreY+4ulNQkzj1GR8DeuGHsAde4VYJ5h4FOsDh1kpgKWlE0z6LYyX/nLh3Y8r FIz9+4v7jZVDZrFisTLZs0fw8nfxE6v1qK7qRZb5HVSqQhWi1pnxv3kFCacAOsAg4A5D mTsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791368417; x=1791973217; h=content-transfer-encoding:content-type:mime-version:message-id:date :references:in-reply-to:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=rFAvUO4Y/vcYHM1X2jKNJMuKbU0DG4p6en3YHWz9DUE=; b=dkNR9Zf71BA4LbQN05ZJeZ2Qs9KcxTp4mBg6TBykr6/xNNUQasBNlvbCF8Ml43O8AQ 1g+skHahqTacJ50FysNUfCyAMqHjXpOAZxAan2t3GBQ7khBjGi4lBJA2eYOy9mS6w2TC gU7H1l+PlZd8Wv7E+XCgE/9/Q8gzrvZItjK8sA06jrCXk76/CN7yGgeCSXh6XVwV1WOp 0hP+6C4AM16OZ2O1MENpKsS7mzQQX1b4MFw1xSf30aR5f6QXTgjqvc0RWTsriWSsQVD9 F8Yn9G3D29RLSwmWTCJj8MvP77GwbbaLYM9KM/JjmaWetd743VxS5/39hTNFf5lcNEEO tYvg== X-Forwarded-Encrypted: i=1; AKwUvBy+1/xjxQD2rx5qjxSt1LWjdfOORghSG2WEKsfbM5EV5BI8JpgoS5bGBNP3n2NsPvOJ5HyAK2A=@vger.kernel.org X-Gm-Message-State: AFuF++lQGHcC0KTkp+TwoCt6Y1bp6LwcYLMG0wMEeIjkW7pduS2mkFmd lLdap1ViRWr4IHle3BbQKHUcLdAuvWLFfhQ5gFsvyyRulc8aTlTeJHvlQII9nH5dJ19/6K7u9c/ nl72Xg+AhNVNAaoH0Vk3VvcmFOSeewAi/hyHkmlxAHyofA5Gs6kMr6YPrpw== X-Gm-Gg: AYBFou0VDeXo5voKjHyJ5s5PK6K8CxVcZaoHWDq4EmIMaHOA2pxV9GRpSo600gSXxM9 KkHKfFtBXqjHEBcI7CIdbFDb4mGWgQTWMPrTDt2dBEgjHb/XF4TIiTtB6rJ2/xfd5oSz4RgAOvL s1iw/Zf5meovU3+Q0Q8n1XUTGun5lZ6L6/z1Up29zlKmP2NFMLwo8gfKLwC5rRl996Iq53LMp6M Mk7z4o0Og7YkcOj84865EzFwe76foNkUgfCmsYvbdHPY675FFGMDFU9Tso0Rn6Yeqzh8qvpWuyV 7nHC1RscajHPngov1Ytbs+YC04Q2JOajLMaQr1jQW6hODIhpm9f1p3cNFZ1ZjrMDBghKx1JGqRi F7398hJHABXE+eIMwuzdDAlG4 X-Received: by 2002:a17:906:f592:b0:c29:d31f:7d6a with SMTP id a640c23a62f3a-c317bf67d52mr155718366b.35.1791368416958; Wed, 07 Oct 2026 03:20:16 -0700 (PDT) X-Received: by 2002:a17:906:f592:b0:c29:d31f:7d6a with SMTP id a640c23a62f3a-c317bf67d52mr155715166b.35.1791368416617; Wed, 07 Oct 2026 03:20:16 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c317c32af4fsm81250166b.63.2026.10.07.03.20.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2026 03:20:15 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id D29F7A4CB6C; Wed, 07 Oct 2026 12:20:13 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Tianyi Gao , netdev@vger.kernel.org Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, lorenzo@kernel.org, horms@kernel.org, bpf@vger.kernel.org, shuah@kernel.org, hawk@kernel.org, kernel-team@cloudflare.com, ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, sdf@fomichev.me, linux-kselftest@vger.kernel.org, Tianyi Gao Subject: Re: [PATCH net 1/2] veth: fix peer NETDEV_XDP_ACT_NDO_XMIT after GRO is toggled while down In-Reply-To: <20261006173241.65945-2-tianyi@cloudflare.com> References: <20261006173241.65945-1-tianyi@cloudflare.com> <20261006173241.65945-2-tianyi@cloudflare.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 07 Oct 2026 12:20:13 +0200 Message-ID: <87cxtlu80y.fsf@toke.dk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Tianyi Gao writes: > A veth device advertises NETDEV_XDP_ACT_NDO_XMIT only if its peer has an > XDP program attached or GRO enabled, that is, only if the peer will have > NAPI to receive the frames. > > veth_set_features() updates the peer's flag when GRO is toggled, but > returns early if the device is down, and veth_open() only refreshes the > flags of the device being opened. Toggling GRO while the device is down > therefore leaves the peer's flag stale after the device comes up. > > If GRO was enabled while down, the device comes up with NAPI but the > peer does not advertise NDO_XMIT, and devmap rejects redirects to the > peer with -EOPNOTSUPP. If GRO was disabled while down, the device comes > up without NAPI but the peer still advertises NDO_XMIT, so redirects are > accepted and then dropped in veth_xdp_xmit() with -ENXIO. > > Commit 7a6102aa6df0 ("veth: Update XDP feature set when bringing up > device") made veth_open() refresh the device's own flags. Refresh the > peer's flags there too. The peer's flag depends on this device's XDP > program and GRO setting, not on whether the peer is up, so it is > correct to set it even if the peer is down. > > Fixes: 8267fc71abb2 ("veth: take into account peer device for NETDEV_XDP_= ACT_NDO_XMIT xdp_features flag") > Signed-off-by: Tianyi Gao Reviewed-by: Toke H=C3=B8iland-J=C3=B8rgensen