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 AD2AEC432BE for ; Fri, 23 Jul 2021 15:55:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 988D460E0C for ; Fri, 23 Jul 2021 15:55:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235807AbhGWPO0 (ORCPT ); Fri, 23 Jul 2021 11:14:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235796AbhGWPON (ORCPT ); Fri, 23 Jul 2021 11:14:13 -0400 Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAAD0C061575; Fri, 23 Jul 2021 08:54:44 -0700 (PDT) Received: by mail-yb1-xb2f.google.com with SMTP id k65so2960654yba.13; Fri, 23 Jul 2021 08:54:44 -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=ju/B2HenKORYoXITNR9EZG98UjeDf3i93fjAOU3sJWI=; b=D52BfguKCAbmlldWH8RLszuxDym1CVOSEo2xYr+Rm3gcCg2OOdbw4XowjhRSrZJRoa /chtuzLyfzrYtVutb2d6/H9GcpFHjKhjPitfKzzY0hjWx1gs6SfMDs0SkErkWydYO0MX so4L0JdI3vt9GQRZuxXwBFX2Ji8btsq+85yPXt5oppYCsINSPS1TQlTDnyUz3VEUp/y1 JxXyCmURX1JodWrpVp8pHOsi7edE9yp+HwKKTiQgEBORak/S8WD+4ij0OBkm58vqr7Oo xZGL5Fm1D1cTSAfjemu7YV5K2rnw0fAWtKgOxDHSGN1HNmw/eD8i9i+VCE5ROzqGdGGY yJ5Q== 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=ju/B2HenKORYoXITNR9EZG98UjeDf3i93fjAOU3sJWI=; b=eVq6TLzC4UM9t4BoFXlwB9zMLwslUvAleI4XNwJHL+5DE0xCMaLzRcHFFStqN1yNNo ArxvY8eH5Y46T/14AbRqBvqE8MEHhRCcEFnWBWJxaY/2MFc4PPuWIhs6caH2BuTKjYfD ksuDE7eHwu2yyIZWe28O72XYR2wcA5lG2TR/oWKOO0ooNjnjgYwm/Zb6/dBYLhCHVWb6 f1+azi7dBnGT6SQn42IX1AiG27EZ+tTuZDlmsvSgNLsUBxPgP/k0EfVF78jxPgpVdmas tzQnwl/1beSYhLgtmRbuW01t39axQUwf+EyjUA3gkRH8rwC2VTQQBGiJ5D0lfm8jYgKf 1LQA== X-Gm-Message-State: AOAM531gkmNjYqp7oEsYmYpVw6srV81jiM3L6FRBXgJv7iu4L+utov9+ FwUnQGMwTk8WO5be8ia/4D83LO6keMQ6yvm5u4k= X-Google-Smtp-Source: ABdhPJx2dgVzeViGJbQUaH5bDCjEqywhytUdNHAGSdhFL2483rx8zKidXpkrqP1caW8z6OxKXarqkUaQPFxlEtC9hkI= X-Received: by 2002:a25:b203:: with SMTP id i3mr7229599ybj.260.1627055683949; Fri, 23 Jul 2021 08:54:43 -0700 (PDT) MIME-Version: 1.0 References: <20210721153808.6902-1-quentin@isovalent.com> <20210721153808.6902-3-quentin@isovalent.com> <88d3cd19-5985-ad73-5f23-4f6f7d1b1be2@isovalent.com> In-Reply-To: <88d3cd19-5985-ad73-5f23-4f6f7d1b1be2@isovalent.com> From: Andrii Nakryiko Date: Fri, 23 Jul 2021 08:54:32 -0700 Message-ID: Subject: Re: [PATCH bpf-next v2 2/5] libbpf: rename btf__get_from_id() as btf__load_from_kernel_by_id() To: Quentin Monnet Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf , John Fastabend Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jul 23, 2021 at 2:31 AM Quentin Monnet wrote: > > 2021-07-22 17:39 UTC-0700 ~ Andrii Nakryiko > > On Wed, Jul 21, 2021 at 8:38 AM Quentin Monnet wrote: > >> > >> Rename function btf__get_from_id() as btf__load_from_kernel_by_id() to > >> better indicate what the function does. Change the new function so that, > >> instead of requiring a pointer to the pointer to update and returning > >> with an error code, it takes a single argument (the id of the BTF > >> object) and returns the corresponding pointer. This is more in line with > >> the existing constructors. > >> > >> The other tools calling the deprecated btf__get_from_id() function will > >> be updated in a future commit. > >> > >> References: > >> > >> - https://github.com/libbpf/libbpf/issues/278 > >> - https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis > >> > >> v2: > >> - Instead of a simple renaming, change the new function to make it > >> return the pointer to the btf struct. > >> - API v0.5.0 instead of v0.6.0. > > > > We generally keep such version changes to cover letters. It keeps each > > individual commit clean and collects full history in the cover letter > > which becomes a body of merge commit when the whole patch set is > > applied. For next revision please consolidate the history in the cover > > letter. Thanks! > > OK will do. > I've seen other folks detailing the changes on individual patches, and > done so in the past, although it's true the current trend is to have it > in the cover letter (and I understand the motivation). > > > > >> > >> Signed-off-by: Quentin Monnet > >> Acked-by: John Fastabend > >> --- > >> tools/lib/bpf/btf.c | 25 +++++++++++++++++-------- > >> tools/lib/bpf/btf.h | 1 + > >> tools/lib/bpf/libbpf.c | 5 +++-- > >> tools/lib/bpf/libbpf.map | 1 + > >> 4 files changed, 22 insertions(+), 10 deletions(-) > >> > >> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > >> index 7e0de560490e..6654bdee7ad7 100644 > >> --- a/tools/lib/bpf/btf.c > >> +++ b/tools/lib/bpf/btf.c > >> @@ -1383,21 +1383,30 @@ struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf) > >> return btf; > >> } > >> > >> +struct btf *btf__load_from_kernel_by_id(__u32 id) > >> +{ > >> + struct btf *btf; > >> + int btf_fd; > >> + > >> + btf_fd = bpf_btf_get_fd_by_id(id); > >> + if (btf_fd < 0) > >> + return ERR_PTR(-errno); > > > > please use libbpf_err_ptr() for consistency, see > > bpf_object__open_mem() for an example > > I can do that, but I'll need to uncouple btf__get_from_id() from the new > function. If it calls btf__load_from_kernel_by_id() and > LIBBPF_STRICT_CLEAN_PTRS is set, it would change its return value. No it won't, if libbpf_get_error() is used right after the API call. With CLEAN_PTRS the result pointer is NULL but actual error is passed through errno. libbpf_get_error() knows about this and extracts error from errno if passed NULL pointer. With returning ERR_PTR(-errno) from btf__load_from_kernel_by_id() you are breaking CLEAN_PTRS guarantees. > > > > >> + > >> + btf = btf_get_from_fd(btf_fd, NULL); > >> + close(btf_fd); > >> + > >> + return libbpf_ptr(btf); > >> +} > >> + > >> int btf__get_from_id(__u32 id, struct btf **btf) > >> { > >> struct btf *res; > >> - int err, btf_fd; > >> + int err; > >> > >> *btf = NULL; > >> - btf_fd = bpf_btf_get_fd_by_id(id); > >> - if (btf_fd < 0) > >> - return libbpf_err(-errno); > >> - > >> - res = btf_get_from_fd(btf_fd, NULL); > >> + res = btf__load_from_kernel_by_id(id); > >> err = libbpf_get_error(res); > >> > >> - close(btf_fd); > >> - > >> if (err) > >> return libbpf_err(err); > >> > >> diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h > >> index fd8a21d936ef..3db9446bc133 100644 > >> --- a/tools/lib/bpf/btf.h > >> +++ b/tools/lib/bpf/btf.h > >> @@ -68,6 +68,7 @@ LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size); > >> LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset); > >> LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset); > >> LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); > >> +LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id); > > > > let's move this definition to after btf__parse() to keep all > > "constructors" together (we can move btf__get_from_id() there for > > completeness as well, I suppose). > > I thought about that but wasn't sure, OK will do. Ok, thanks. > > > > >> LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, > >> __u32 expected_key_size, > >> __u32 expected_value_size, > >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > >> index 242e97892043..eff005b1eba1 100644 > >> --- a/tools/lib/bpf/libbpf.c > >> +++ b/tools/lib/bpf/libbpf.c > >> @@ -9576,8 +9576,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) > >> { > >> struct bpf_prog_info_linear *info_linear; > >> struct bpf_prog_info *info; > >> - struct btf *btf = NULL; > >> int err = -EINVAL; > >> + struct btf *btf; > >> > >> info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0); > >> err = libbpf_get_error(info_linear); > >> @@ -9591,7 +9591,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) > >> pr_warn("The target program doesn't have BTF\n"); > >> goto out; > >> } > >> - if (btf__get_from_id(info->btf_id, &btf)) { > >> + btf = btf__load_from_kernel_by_id(info->btf_id); > >> + if (libbpf_get_error(btf)) { > > > > there seems to be a bug in existing code and you are keeping it. On > > error err will be 0. Let's fix it. Same for above if (!info->btf_id), > > please fix that as well while you are at it. > > Oh right, I saw that err was initialised at -EINVAL and did not notice > it was changed for the info_linear. I'll address it. cool, thanks