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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 5E692C4CECE for ; Sat, 12 Oct 2019 16:57:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AD492190F for ; Sat, 12 Oct 2019 16:57:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pO9lZhHT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729497AbfJLQ5E (ORCPT ); Sat, 12 Oct 2019 12:57:04 -0400 Received: from mail-lf1-f67.google.com ([209.85.167.67]:40488 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727884AbfJLQzE (ORCPT ); Sat, 12 Oct 2019 12:55:04 -0400 Received: by mail-lf1-f67.google.com with SMTP id d17so9100574lfa.7; Sat, 12 Oct 2019 09:55:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vDizdu9ZTbUiBuM21uWD34hEvaAlCgMSnuRFZcYt/XY=; b=pO9lZhHTzapFnKp1A1SeeDMdu5u74rTS1jKEzLWhdZWIBvCqZ5VkC7bfHAjqO4p9IL /Q/jJQ4URnIkx4i2dJix7O9EwR65uLxLwBI2S+LgQ5vzoCq2UqyHbidijxOFXtUq90fo svPrgAsWMbFjhjm5FCVnqMViC72WjMFhnO2RyfjWe194+gSBPNclNX5eah/OnwzooGRi HlqxYi7VTuWk90ABAxjmppgitjviM3ZGDU1XFEpCplO0+mZ9p3pCOQjNJSXt9T1SVEqK +yoVM6fxjw7VDkf0DhF8/bdW5JH28R13veKHZOWY7O1o8A9vLbaG+ATYUVaAlBoI5JV1 P61Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vDizdu9ZTbUiBuM21uWD34hEvaAlCgMSnuRFZcYt/XY=; b=Y8oIlf5zykbLhmKJVfkA6pwJVwYp6vgJ9CwwsDvpaJibfZfIo97m+WthXdoVnt4Eyc Ez/ZUahb6lyxJQh4R2CLNrZlmlnJvE+JL3zkebI3hsmGQTkPnEDP5WTbHSG6ZEn/gl9r zu2wR9QEic/7yuOwerLwybWqRU5Lyw3RHavy/aLPNPmWwmsCQljJ9qwLbPsbDRoeRta5 +W4+SWlVXbtmzjiOQanOrjJCJ2QvHIN9qL7eJZ8zlG6R9jjWBZZX64ZO6s7xxm9OHhni 36AKDexX2hVQG0zKUjd1mBAS9qhtGCTHLgn6PTB0YUXOyqXg+oClJmVBk0hw1cu+cc+Y HdGg== X-Gm-Message-State: APjAAAWx5pNDJ+2GW25YJhLCliP2s65CxpsTjqufW128tajmeEhTiNTo DLZNgkFB2KIAIZ2Pa9JHGSS+lhn4MToa5SVZc54= X-Google-Smtp-Source: APXvYqz1YrbXUhmqbBUp2gf/ItCVN5nB4DPteK5Mfohp/t0wE7TqKOkPrdGGItfBLszOa+G9Z37EtaAM0p5+5/0eyLk= X-Received: by 2002:ac2:597b:: with SMTP id h27mr11986416lfp.100.1570899301833; Sat, 12 Oct 2019 09:55:01 -0700 (PDT) MIME-Version: 1.0 References: <1570530208-17720-1-git-send-email-magnus.karlsson@intel.com> <5d9ce369d6e5_17cc2aba94c845b415@john-XPS-13-9370.notmuch> <5da0ed0b2a26d_70f72aad5dc6a5b8db@john-XPS-13-9370.notmuch> In-Reply-To: <5da0ed0b2a26d_70f72aad5dc6a5b8db@john-XPS-13-9370.notmuch> From: Alexei Starovoitov Date: Sat, 12 Oct 2019 09:54:50 -0700 Message-ID: Subject: Re: [PATCH bpf] libbpf: fix compatibility for kernels without need_wakeup To: John Fastabend Cc: Magnus Karlsson , Magnus Karlsson , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Alexei Starovoitov , Daniel Borkmann , Network Development , Jonathan Lemon , bpf Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Oct 11, 2019 at 1:58 PM John Fastabend wrote: > > Magnus Karlsson wrote: > > On Tue, Oct 8, 2019 at 9:29 PM John Fastabend wrote: > > > > > > Magnus Karlsson wrote: > > > > When the need_wakeup flag was added to AF_XDP, the format of the > > > > XDP_MMAP_OFFSETS getsockopt was extended. Code was added to the kernel > > > > to take care of compatibility issues arrising from running > > > > applications using any of the two formats. However, libbpf was not > > > > extended to take care of the case when the application/libbpf uses the > > > > new format but the kernel only supports the old format. This patch > > > > adds support in libbpf for parsing the old format, before the > > > > need_wakeup flag was added, and emulating a set of static need_wakeup > > > > flags that will always work for the application. > > > > > > > > Fixes: a4500432c2587cb2a ("libbpf: add support for need_wakeup flag in AF_XDP part") > > > > Reported-by: Eloy Degen > > > > Signed-off-by: Magnus Karlsson > > > > --- > > > > tools/lib/bpf/xsk.c | 109 +++++++++++++++++++++++++++++++++++++--------------- > > > > 1 file changed, 78 insertions(+), 31 deletions(-) > > > > > > > > diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c > > > > index a902838..46f9687 100644 > > > > --- a/tools/lib/bpf/xsk.c > > > > +++ b/tools/lib/bpf/xsk.c > > > > @@ -44,6 +44,25 @@ > > > > #define PF_XDP AF_XDP > > > > #endif > > > > > > > > +#define is_mmap_offsets_v1(optlen) \ > > > > + ((optlen) == sizeof(struct xdp_mmap_offsets_v1)) > > > > + > > > > +#define get_prod_off(ring) \ > > > > + (is_mmap_offsets_v1(optlen) ? \ > > > > + ((struct xdp_mmap_offsets_v1 *)&off)->ring.producer : \ > > > > + off.ring.producer) > > > > +#define get_cons_off(ring) \ > > > > + (is_mmap_offsets_v1(optlen) ? \ > > > > + ((struct xdp_mmap_offsets_v1 *)&off)->ring.consumer : \ > > > > + off.ring.consumer) > > > > +#define get_desc_off(ring) \ > > > > + (is_mmap_offsets_v1(optlen) ? \ > > > > + ((struct xdp_mmap_offsets_v1 *)&off)->ring.desc : off.ring.desc) > > > > +#define get_flags_off(ring) \ > > > > + (is_mmap_offsets_v1(optlen) ? \ > > > > + ((struct xdp_mmap_offsets_v1 *)&off)->ring.consumer + sizeof(u32) : \ > > > > + off.ring.flags) > > > > + > > > > > > It seems the only thing added was flags right? If so seems we > > > only need the last one there, get_flags_off(). I think it would > > > be a bit cleaner to just use the macros where its actually > > > needed IMO. > > > > The flag is indeed added to the end of struct xdp_ring_offsets, but > > this struct is replicated four times in the struct xdp_mmap_offsets, > > so the added flags are present four time there at different offsets. > > This means that 3 out of the 4 prod, cons and desc variables are > > located at different offsets from the original. Do not know how I can > > get rid of these macros in this case. But it might just be me not > > seeing it, of course :-). > > Not sure I like it but not seeing a cleaner solution that doesn't cause > larger changes so... > > Acked-by: John Fastabend Frankly above hack looks awful. What is _v1 ?! Is it going to be _v2? What was _v0? I also don't see how this is a fix. imo bpf-next is more appropriate and if "large changes" are necessary then go ahead and do them. We're not doing fixes-branches in libbpf. The library always moves forward and compatible with all older kernels.