From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2703C2B9F4 for ; Mon, 28 Jun 2021 10:43:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A46E161954 for ; Mon, 28 Jun 2021 10:43:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232654AbhF1KqC (ORCPT ); Mon, 28 Jun 2021 06:46:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232486AbhF1Kp7 (ORCPT ); Mon, 28 Jun 2021 06:45:59 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 037D9C061574 for ; Mon, 28 Jun 2021 03:43:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=SeiXqnhgD0iOHnxE66GM539cLeCDyhLBnDh6JGXHg3E=; b=Rp/7fmNATfuIUxFiAeAl+/fs7j hVRhDMUhZnVqB2NjKK9HLcqEHhVn79GJGzaVCFrrrVfLWLLiVscfylRB0Ry540Sb4RdbIl6Meepnb caqDm6QL0hLaD0+xKtryvAD/fWwQOMr2C6Ktfgto7+M9DotCaJqKSdrS9WBBEOROgLpIrjU9GiJGJ L3Q2IaYchDwzzhVG5Dque+SO9kpw3cgnJ5Us078CkkO/Y0KC4R2oecl9Vk0IjNad5Qxs7avtbJq+l poXKxeTY1FNNJGgwPd+rOZbVuyowBpEanIRNOsxXN0FYC/edGtEqSRM4ixwKCredkgUg49kCoLqni 8e/hR30A==; Received: from [54.239.6.185] (helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lxojl-007fo7-3q; Mon, 28 Jun 2021 10:43:33 +0000 Message-ID: <3a47986a65825121e67ccf831d0b9938862a6e36.camel@infradead.org> Subject: Re: [PATCH v3 4/5] net: tun: fix tun_xdp_one() for IFF_TUN mode From: David Woodhouse To: Jason Wang , netdev@vger.kernel.org Cc: Eugenio =?ISO-8859-1?Q?P=E9rez?= , Willem de Bruijn Date: Mon, 28 Jun 2021 11:43:30 +0100 In-Reply-To: <8914d56f-8059-71df-ab51-9fbb9637e45a@redhat.com> References: <03ee62602dd7b7101f78e0802249a6e2e4c10b7f.camel@infradead.org> <20210624123005.1301761-1-dwmw2@infradead.org> <20210624123005.1301761-4-dwmw2@infradead.org> <32071ebb3f433b239394e243a6fc8a2bc6d36dcb.camel@infradead.org> <8914d56f-8059-71df-ab51-9fbb9637e45a@redhat.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-ul0VtqKlBIN4pCa1h24u" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --=-ul0VtqKlBIN4pCa1h24u Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2021-06-28 at 12:27 +0800, Jason Wang wrote: > > If we're going to continue to *not* check on the XDP path, we similarly > > need a proof that it can't be fragmented. And also a reason to bother > > with the "optimisation", of course. >=20 >=20 > For XDP path, we simply need to add a length check since the packet is= =20 > always a linear memory. Sure, but in that case skb_headlen is going to be enough to cover ETH_HLEN, and that's the very first thing that the standard inline version of pskb_may_pull() checks, without ever even having to make an out-of-line call. So there's just no reason ever for us *not* to keep it really simple, and use pskb_may_pull() in all cases. --=-ul0VtqKlBIN4pCa1h24u Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q cXuzkOpibq2YurVStHAiGqAOMGMXhcVGqPuGhcVcVzVUjsvEzAV9Po9K2rpZ52FE4rDkpDK1pBK+ 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