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=-17.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 6FEFDC433EF for ; Thu, 9 Sep 2021 22:31:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 483D26105A for ; Thu, 9 Sep 2021 22:31:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237413AbhIIWdF (ORCPT ); Thu, 9 Sep 2021 18:33:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbhIIWdF (ORCPT ); Thu, 9 Sep 2021 18:33:05 -0400 Received: from mail-yb1-xb2e.google.com (mail-yb1-xb2e.google.com [IPv6:2607:f8b0:4864:20::b2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D7ADC061574 for ; Thu, 9 Sep 2021 15:31:55 -0700 (PDT) Received: by mail-yb1-xb2e.google.com with SMTP id z5so7100333ybj.2 for ; Thu, 09 Sep 2021 15:31:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=8AIUb9ODQ7DY9LJR6OGybHtKIU6ZG/v7rZ+XcGbDxDk=; b=GdPRE3sZKi0Bjj9cqxZG+pkFgmpN+hNI5hY4fMRZ7Xs++7mmNpqp7E0kF79kuLsyEJ xWE7dITm7RC60kk0ziqfyjv0b6PM4fpM0CDRwO1Vj2apy5t0QeVe+Ok4Y+WO5JVBGF7/ wA66Z9FgmYsUlO3XcXSPnT9WWY2wbDzFPYBJupXqYOuf6BlPexBrwoZilC0QXW4YcuLQ Ocee3XhuJAEgCL8Kk0eae9cwAdaNZrGSO3NKGo8cYhU0uRSrEWmb0ZjUcE0gdoEsSdeB RMGP9co+gV0SUvUHXPyPf2Xuc5AJVtodEEvDInB68uIFzqh/zM13eNeZ2D4fMuRCZzC7 9UKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=8AIUb9ODQ7DY9LJR6OGybHtKIU6ZG/v7rZ+XcGbDxDk=; b=RNPuZtgrV0u7ikpq4Do7XZe9Oj2Vzjs1CXZwG8XHTPjzDPcjgNth9ShcPPkI0xQo1T xd/OnTSqkWv1HDHtI/ZlgXbhimNY0XLkQBOUyZ0zgTBVQ1iFia09brSIGeJKUyg+u+rN hbSlm4FcNoMloQguboMC7XqVMZGRL6fBsMDWN2GxiTisc1qdY9cv1Uv6GbUoCMYxBIse OfDWBjKWTmBNTu0Rx1+Hl/eSV7I3247UcE7e2htt6z9svHfhS4TapT8VvLh+rrFE5tdn VBvgJaocK+pSCUzMXiaqLwNp+BH6tzcvTH32sz9TpVPiXT4apTeOc6Y7TZuQj6aORiak HDlA== X-Gm-Message-State: AOAM531vba2wUgSme/5TGFGKwu6yTqAMitpjB/5ObL7DDkaNQPLJz9js WlTEMQaHzE/F9Gj0xhwJhVKEWahQU39HkOIza+g= X-Google-Smtp-Source: ABdhPJz0TgHjM6wGx0qARkDhQdwfuzMX2uVm4aedSF/a/h/ENrY5rYRwjqdoaIi91ZMV0WYHXuPdHrmF/sQ4nhsBVcQ= X-Received: by 2002:a5b:702:: with SMTP id g2mr6803683ybq.307.1631226714345; Thu, 09 Sep 2021 15:31:54 -0700 (PDT) MIME-Version: 1.0 References: <20210908213226.1871016-1-andrii@kernel.org> <4287e56e-a91a-1f39-5dae-14ecabe537db@iogearbox.net> In-Reply-To: <4287e56e-a91a-1f39-5dae-14ecabe537db@iogearbox.net> From: Andrii Nakryiko Date: Thu, 9 Sep 2021 15:31:43 -0700 Message-ID: Subject: Re: [PATCH v3 bpf-next] libbpf: add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations To: Daniel Borkmann Cc: Andrii Nakryiko , bpf , Alexei Starovoitov , Quentin Monnet , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Sep 9, 2021 at 2:43 PM Daniel Borkmann wrote: > > On 9/9/21 8:08 PM, Andrii Nakryiko wrote: > > On Thu, Sep 9, 2021 at 9:37 AM Andrii Nakryiko > > wrote: > >> On Thu, Sep 9, 2021 at 5:58 AM Daniel Borkmann wrote: > >>> On 9/8/21 11:32 PM, Andrii Nakryiko wrote: > >>>> From: Quentin Monnet > >>>> > >>>> Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare > >>>> the deprecation of two API functions. This macro marks functions as deprecated > >>>> when libbpf's version reaches the values passed as an argument. > >>>> > >>>> As part of this change libbpf_version.h header is added with recorded major > >>>> (LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros. > >>>> They are now part of libbpf public API and can be relied upon by user code. > >>>> libbpf_version.h is installed system-wide along other libbpf public headers. > >>>> > >>>> Due to this new build-time auto-generated header, in-kernel applications > >>>> relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to > >>>> include libbpf's output directory as part of a list of include search paths. > >>>> Better fix would be to use libbpf's make_install target to install public API > >>>> headers, but that clean up is left out as a future improvement. The build > >>>> changes were tested by building kernel (with KBUILD_OUTPUT and O= specified > >>>> explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No > >>>> problems were detected. > >>>> > >>>> Note that because of the constraints of the C preprocessor we have to write > >>>> a few lines of macro magic for each version used to prepare deprecation (0.6 > >>>> for now). > >>>> > >>>> Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of > >>>> btf__get_from_id() and btf__load(), which are replaced by > >>>> btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively, > >>>> starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]). > >>>> > >>>> [0] Closes: https://github.com/libbpf/libbpf/issues/278 > >>>> > >>>> Co-developed-by: Quentin Monnet > >>>> Signed-off-by: Quentin Monnet > >>>> Signed-off-by: Andrii Nakryiko > >>>> --- > >>>> v2->v3: > >>>> - adding `sleep 10` revealed two more missing dependencies in resolve_btfids > >>>> and selftest/bpf's bench, which were fixed (BPF CI); > >>>> v1->v2: > >>>> - fix bpf_preload build by adding dependency for iterators/iterators.o on > >>>> libbpf.a generation (caught by BPF CI); > >>>> > >>>> kernel/bpf/preload/Makefile | 7 +++++-- > >>>> tools/bpf/bpftool/Makefile | 4 ++++ > >>>> tools/bpf/resolve_btfids/Makefile | 6 ++++-- > >>>> tools/lib/bpf/Makefile | 24 +++++++++++++++++------- > >>>> tools/lib/bpf/btf.h | 2 ++ > >>>> tools/lib/bpf/libbpf_common.h | 19 +++++++++++++++++++ > >>>> tools/testing/selftests/bpf/Makefile | 4 ++-- > >>>> 7 files changed, 53 insertions(+), 13 deletions(-) > >>>> > >>>> diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile > >>>> index 1951332dd15f..ac29d4e9a384 100644 > >>>> --- a/kernel/bpf/preload/Makefile > >>>> +++ b/kernel/bpf/preload/Makefile > >>>> @@ -10,12 +10,15 @@ LIBBPF_OUT = $(abspath $(obj)) > >>>> $(LIBBPF_A): > >>>> $(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a > >>>> > >>>> -userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ > >>>> +userccflags += -I$(LIBBPF_OUT) -I $(srctree)/tools/include/ \ > >>>> + -I $(srctree)/tools/include/uapi \ > >>>> -I $(srctree)/tools/lib/ -Wno-unused-result > >>>> > >>>> userprogs := bpf_preload_umd > >>>> > >>>> -clean-files := $(userprogs) bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/ > >>>> +clean-files := $(userprogs) libbpf_version.h bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/ > >>>> + > >>>> +$(obj)/iterators/iterators.o: $(LIBBPF_A) > >>>> > >>>> bpf_preload_umd-objs := iterators/iterators.o > >>>> bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz > >>> > >>> One small issue I ran into by accident while testing: > >>> > >>> [root@linux bpf-next]# make -j8 kernel/bpf/ > >>> SYNC include/config/auto.conf.cmd > >>> DESCEND objtool > >>> CALL scripts/atomic/check-atomics.sh > >>> CALL scripts/checksyscalls.sh > >>> CC kernel/bpf/syscall.o > >>> AR kernel/bpf/preload/built-in.a > >>> CC [M] kernel/bpf/preload/bpf_preload_kern.o > >>> CC [U] kernel/bpf/preload/iterators/iterators.o > >>> In file included from ./tools/lib/bpf/libbpf.h:20, > >>> from kernel/bpf/preload/iterators/iterators.c:10: > >>> ./tools/lib/bpf/libbpf_common.h:13:10: fatal error: libbpf_version.h: No such file or directory > >>> 13 | #include "libbpf_version.h" > >>> | ^~~~~~~~~~~~~~~~~~ > >>> compilation terminated. > >>> make[3]: *** [scripts/Makefile.userprogs:43: kernel/bpf/preload/iterators/iterators.o] Error 1 > >>> make[3]: *** Waiting for unfinished jobs.... > >>> make[2]: *** [scripts/Makefile.build:540: kernel/bpf/preload] Error 2 > >>> make[2]: *** Waiting for unfinished jobs.... > >>> make[1]: *** [scripts/Makefile.build:540: kernel/bpf] Error 2 > >>> make: *** [Makefile:1872: kernel] Error 2 > >>> > >>> For me it was the case where tools/lib/bpf/ was already built _before_ this patch > >>> was applied, then I applied it, and just ran make -j8 kernel/bpf/ where the above > >>> can then be reproduced. I'd assume that as-is, this would affect many folks on update. > >> > >> We had a similar issue even before these changes with resolve_btfids > >> build, because Kbuild doesn't record dependency on libbpf build > >> properly. I'll see how hard it is to record that in a non-intrusive > >> way for both resolve_btfids and preload/iterators, because doing `make > >> resolve_btfids_clean` or, worse, `make clean` isn't great. > > > > Hm... I can't repro this. Both preload/iterators and resolve_btfids > > have $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) > > dependency which will trigger libbpf rebuild if any of libbpf source > > files changes. I added `sleep 1000` and everything under kernel/bpf is > > blocked on this until libbpf build completes. For full kernel build it > > also shouldn't happen because we build resolve_btfids first before > > proceeding to building other files and resolve_btfids should trigger > > libbpf build. > > > > I assume `make clean kernel/bpf` fixed the issue for you in that case? > > No, fixing on that node was done via re-building libbpf via tools/lib/bpf/. > > > Also, how did you build tools/lib/bpf before running `make -j8 kernel/bpf`? > > Basically just i) cd tools/lib/bpf, ii) make clean, iii) make, then applying > the patch, and then running make -j8 kernel/bpf. I just tried on a different > build node with newer user space, and there it indeed triggers a rebuild of > libbpf. On my laptop where I was running into this it didn't. I would suspect > a potential diff in make's behavior (not seen in GNU Make 4.3, seen in GNU > Make 4.2.1, fwiw). Anyway, for this niche case, manual rebuild of tools/lib/bpf > does it ... given it's neither seen in your case nor on newer uspace, I took > it in, lets see how it goes. Thanks! Yeah, thanks! Please let me know if you do run into this again somewhere, though. > > > Honestly, hard to tell how this happens without being able to repro > > this. So far everything seems to be working for me. I've tried with > > and without the KBUILD_OUTPUT envvar set. I also tried O=. > > > >>> > >>> Thanks, > >>> Daniel >