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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 DB9A9C433E0 for ; Fri, 22 May 2020 01:15:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE57220825 for ; Fri, 22 May 2020 01:15:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kimnnaIX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726946AbgEVBP4 (ORCPT ); Thu, 21 May 2020 21:15:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbgEVBPz (ORCPT ); Thu, 21 May 2020 21:15:55 -0400 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAE10C061A0E; Thu, 21 May 2020 18:15:55 -0700 (PDT) Received: by mail-pl1-x644.google.com with SMTP id b12so3733259plz.13; Thu, 21 May 2020 18:15:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UBJGFTXSGo+UPp7XYn9ZrTErT7E+VTF6ZtZtvuINGag=; b=kimnnaIX9OjDVFuqUyxOzv92ZMZrrpfRGwrnZ71/9lSUbvHFc0tUnDaIE4Xcnck6Gw a5dLTYKXNoEGtVndQwEfCAC/gpmHFfuUKz1SwQw0dWGca+U9+m9o4SnD0yBOxUsKp+k3 gesva2dE1ERBr8v+iSkthDEbOuyys5IljmzK1/f9UHJD+Ym7SDVrr/JqjzgSJX76fhzP l1wPXrNlBmfrunzW0D/2gTMmTis/B6DQ+406LC5QJ4K1rmTEaXD81xOZ3rZrj6JJqFXm ZcbFnn/XG+AKDl/+vIP+BWhulijClFp1OcyCJqC6Ncu2WSYEYLj6hPTUnEBSXRkb0iO4 w2WQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UBJGFTXSGo+UPp7XYn9ZrTErT7E+VTF6ZtZtvuINGag=; b=hm28EkCY8B/wJJ8Tt2PSf+CK/8sotNiLZZ/ZhhF/0zcvn9wuZTEZgwN5muTM6jWUXE Umg4oa1kQOoXqAWoefp8VhV+4QUfM0IB6B2MJmibmG29l5B/2X5Bd+ouyPz1GXftJPAI gIMWV2zXAEHpu4p1LY/MAtD8VQFKOpNu+Ivme2AC4JGQBHAeoNEGZJaasUm460R1iy4J 1s9sAbA874BgPTRmfcdQfZjKw/zzazENyjONo1vGMi+/mpQv80dIvBydCyL60+AL0VR5 b19KfC5YqRVlpHR1c6zMpSf6w0lEhK1i7OpzjJHho1TRHNPFyAs10xbddqV7k/192I6O BhLw== X-Gm-Message-State: AOAM530x4zuKOtEW67BMce+N4yFvGRVjX9W1+31S7B7wmFDEGycWANMM MdfMSgP+i0ONUt4xeWAqnmI= X-Google-Smtp-Source: ABdhPJytgXo/c/FEVNde564dMSmkq6Xx7r4V0FNxEUQzKStCiv3Ww464gd10U+TKjvzym3kRwUo2VQ== X-Received: by 2002:a17:90a:21cf:: with SMTP id q73mr1504496pjc.230.1590110155328; Thu, 21 May 2020 18:15:55 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:400::5:e680]) by smtp.gmail.com with ESMTPSA id y75sm5448112pfb.212.2020.05.21.18.15.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2020 18:15:54 -0700 (PDT) Date: Thu, 21 May 2020 18:15:52 -0700 From: Alexei Starovoitov To: Andrii Nakryiko Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, ast@fb.com, daniel@iogearbox.net, andrii.nakryiko@gmail.com, kernel-team@fb.com, "Paul E . McKenney" , Jonathan Lemon Subject: Re: [PATCH v2 bpf-next 4/7] libbpf: add BPF ring buffer support Message-ID: <20200522011552.ak4dkxhqwg6j2koy@ast-mbp.dhcp.thefacebook.com> References: <20200517195727.279322-1-andriin@fb.com> <20200517195727.279322-5-andriin@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200517195727.279322-5-andriin@fb.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, May 17, 2020 at 12:57:24PM -0700, Andrii Nakryiko wrote: > + > +static inline int roundup_len(__u32 len) > +{ > + /* clear out top 2 bits */ > + len <<= 2; > + len >>= 2; what this is for? Overflow prevention? but kernel checked the size already? > + /* add length prefix */ > + len += BPF_RINGBUF_HDR_SZ; > + /* round up to 8 byte alignment */ > + return (len + 7) / 8 * 8; > +} > +