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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5E12C433F5 for ; Wed, 29 Sep 2021 20:39:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D0326124C for ; Wed, 29 Sep 2021 20:39:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346756AbhI2Ukx (ORCPT ); Wed, 29 Sep 2021 16:40:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:39757 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346768AbhI2Ukw (ORCPT ); Wed, 29 Sep 2021 16:40:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632947950; 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: in-reply-to:in-reply-to:references:references; bh=1q2iWY5x6NtiyghS9gn8oPV2bKVir0LZN4nVYY52WSw=; b=gy8wXvUMs4i15vIKh9J3iYNg2uFLJUK9PUFGEC0Ypi3ddDVWk9ODvtDUk5pBde7jutGjZZ zNe8NuqswUZpOtZQWkJrHa7lVfDbirH4mycwu5sjF4m+loe4dvX7pX535GQvLt0WuuB9QQ W1shG2KBGndTTr27AOVaS1l9LSYZO74= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-328-J_ZLJyyQNBWj8H3uXcOodg-1; Wed, 29 Sep 2021 16:39:08 -0400 X-MC-Unique: J_ZLJyyQNBWj8H3uXcOodg-1 Received: by mail-ed1-f70.google.com with SMTP id u17-20020a50d511000000b003daa3828c13so3761496edi.12 for ; Wed, 29 Sep 2021 13:39:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=1q2iWY5x6NtiyghS9gn8oPV2bKVir0LZN4nVYY52WSw=; b=U5z3EkKGPeD/Ch2/PPGUZhes5GH0g3JMTJE48XVD0LFfEqFuE5jsdjqJm8hBEsE6YN A5GmXw4tlQXamyVRXGy7T1LpllEQDR4+iGZOCdoDNaZ51lLx4KP2HVrKxTTbpEWoVD0E BBzJD62X+wWP6ZDp0WUQpyt9mCofQCzj3FQ+dSYdhNnKF6rbKQkfKOX+A358blccg2oL LG2kXeHBZ+dRsHS/pP7MRGuik7o7AfMNK1RvUG8FcB+1ht+QZvePM0laDLXN4/gx1aAF DvSTwtoBmDpivsb+3jxmESAYSPw0PuvqXCgqbD+N3JmculkG+hTXaA++1E1Y1Wz7WeVz qysw== X-Gm-Message-State: AOAM532poUBznUAJNAJGSg/Y1b/6kHExNoxV3fyqdIvGV2nWrxn9SDyD STa7bkVXSiC1X5R19riiwT/JjVmTkTa8XqF4Yz5Q/URtCaz/CNIIbKsECc/4D8+eSmtKkgCAWfb b1ThdEPpeCHiG X-Received: by 2002:a05:6402:847:: with SMTP id b7mr2454878edz.242.1632947946873; Wed, 29 Sep 2021 13:39:06 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwfFNcYoblnlae3U4yRwj0z0K5t3IzH+wSxByDMfEUiBPCc7QN8JJkD0RlKmLnCKsCQnU47yQ== X-Received: by 2002:a05:6402:847:: with SMTP id b7mr2454830edz.242.1632947946525; Wed, 29 Sep 2021 13:39:06 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id v13sm504982edr.0.2021.09.29.13.39.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Sep 2021 13:39:05 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id E2F4718034F; Wed, 29 Sep 2021 22:39:03 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Jakub Kicinski , Alexei Starovoitov Cc: Lorenz Bauer , Lorenzo Bianconi , bpf , Networking , Lorenzo Bianconi , "David S . Miller" , Alexei Starovoitov , Daniel Borkmann , shayagr@amazon.com, John Fastabend , David Ahern , Jesper Dangaard Brouer , Eelco Chaudron , Jason Wang , Alexander Duyck , Saeed Mahameed , Maciej Fijalkowski , "Karlsson, Magnus" , tirthendu.sarkar@intel.com Subject: Re: [PATCH v14 bpf-next 00/18] mvneta: introduce XDP multi-buffer support In-Reply-To: <20210929122229.1d0c4960@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> References: <20210916095539.4696ae27@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <87v92jinv7.fsf@toke.dk> <20210929122229.1d0c4960@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 29 Sep 2021 22:39:03 +0200 Message-ID: <87mtnvi0bc.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Jakub Kicinski writes: > On Wed, 29 Sep 2021 11:54:46 -0700 Alexei Starovoitov wrote: >> I'm missing something. Why do we need a separate flush() helper? >> Can't we do: >> char buf[64], *p; >> p = xdp_mb_pointer(ctx, flags, off, len, buf); >> read/write p[] >> if (p == buf) >> xdp_store_bytes(ctx, off, buf, len, flags); > > Sure we can. That's what I meant by "leave the checking to the program". > It's bike shedding at this point. Yeah, let's discuss the details once we have a patch :) -Toke