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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10F84C4332F for ; Sat, 8 Oct 2022 05:16:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229513AbiJHFQt (ORCPT ); Sat, 8 Oct 2022 01:16:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44784 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229469AbiJHFQr (ORCPT ); Sat, 8 Oct 2022 01:16:47 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B96DA58081; Fri, 7 Oct 2022 22:16:45 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mktcd171TzpVmS; Sat, 8 Oct 2022 13:13:37 +0800 (CST) Received: from [10.174.179.191] (10.174.179.191) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sat, 8 Oct 2022 13:16:42 +0800 Message-ID: <0242ccfe-53e5-5b9d-9fd9-73fa8bd0d7a4@huawei.com> Date: Sat, 8 Oct 2022 13:16:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [bpf-next v7 1/3] bpftool: Add auto_attach for bpf prog load|loadall To: Quentin Monnet , , , , , , , , , , , , , , , , , CC: , , , References: <1664277676-2228-1-git-send-email-wangyufen@huawei.com> <83307f48-bef0-bff8-e3b5-f8df7a592678@isovalent.com> From: wangyufen In-Reply-To: <83307f48-bef0-bff8-e3b5-f8df7a592678@isovalent.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.191] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/10/1 0:26, Quentin Monnet 写道: > Tue Sep 27 2022 12:21:14 GMT+0100 ~ Wang Yufen >> Add auto_attach optional to support one-step load-attach-pin_link. > Nit: Now "autoattach" instead of "auto_attach". Same in commit title. will change in v8, thanks. > >> For example, >> $ bpftool prog loadall test.o /sys/fs/bpf/test autoattach >> >> $ bpftool link >> 26: tracing name test1 tag f0da7d0058c00236 gpl >> loaded_at 2022-09-09T21:39:49+0800 uid 0 >> xlated 88B jited 55B memlock 4096B map_ids 3 >> btf_id 55 >> 28: kprobe name test3 tag 002ef1bef0723833 gpl >> loaded_at 2022-09-09T21:39:49+0800 uid 0 >> xlated 88B jited 56B memlock 4096B map_ids 3 >> btf_id 55 >> 57: tracepoint name oncpu tag 7aa55dfbdcb78941 gpl >> loaded_at 2022-09-09T21:41:32+0800 uid 0 >> xlated 456B jited 265B memlock 4096B map_ids 17,13,14,15 >> btf_id 82 >> >> $ bpftool link >> 1: tracing prog 26 >> prog_type tracing attach_type trace_fentry >> 3: perf_event prog 28 >> 10: perf_event prog 57 >> >> The autoattach optional can support tracepoints, k(ret)probes, >> u(ret)probes. >> >> Signed-off-by: Wei Yongjun >> Signed-off-by: Wang Yufen >> --- >> v6 -> v7: add info msg print and update doc for the skip program >> v5 -> v6: skip the programs not supporting auto-attach, >> and change optional name from "auto_attach" to "autoattach" >> v4 -> v5: some formatting nits of doc >> v3 -> v4: rename functions, update doc, bash and do_help() >> v2 -> v3: switch to extend prog load command instead of extend perf >> v2: https://patchwork.kernel.org/project/netdevbpf/patch/20220824033837.458197-1-weiyongjun1@huawei.com/ >> v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@huawei.com/ >> tools/bpf/bpftool/prog.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 79 insertions(+), 2 deletions(-) >> >> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c >> index c81362a..84eced8 100644 >> --- a/tools/bpf/bpftool/prog.c >> +++ b/tools/bpf/bpftool/prog.c >> @@ -1453,6 +1453,72 @@ static int do_run(int argc, char **argv) >> return ret; >> } >> >> +static int >> +auto_attach_program(struct bpf_program *prog, const char *path) >> +{ >> + struct bpf_link *link; >> + int err; >> + >> + link = bpf_program__attach(prog); >> + if (!link) >> + return -1; >> + >> + err = bpf_link__pin(link, path); >> + if (err) { >> + bpf_link__destroy(link); >> + return err; >> + } >> + return 0; >> +} >> + >> +static int pathname_concat(const char *path, const char *name, char *buf) >> +{ >> + int len; >> + >> + len = snprintf(buf, PATH_MAX, "%s/%s", path, name); >> + if (len < 0) >> + return -EINVAL; >> + if (len >= PATH_MAX) >> + return -ENAMETOOLONG; >> + >> + return 0; >> +} >> + >> +static int >> +auto_attach_programs(struct bpf_object *obj, const char *path) >> +{ >> + struct bpf_program *prog; >> + char buf[PATH_MAX]; >> + int err; >> + >> + bpf_object__for_each_program(prog, obj) { >> + err = pathname_concat(path, bpf_program__name(prog), buf); >> + if (err) >> + goto err_unpin_programs; >> + >> + err = auto_attach_program(prog, buf); >> + if (!err) >> + continue; >> + if (errno == EOPNOTSUPP) >> + p_info("Program %s does not support autoattach", >> + bpf_program__name(prog)); >> + else >> + goto err_unpin_programs > With this code, if auto-attach fails, then we skip this program and move > on to the next. That's an improvement, but in that case the program > won't remain loaded in the kernel after bpftool exits. My suggestion in > my previous message (sorry if it was not clear) was to fall back to > regular pinning in that case (bpf_obj_pin()), along with the p_info() > message, so we can have the program pinned but not attached and let the > user know. If regular pinning fails as well, then we should unpin all > and error out, for consistency with bpf_object__pin_programs(). > > And in that case, the (errno == EOPNOTSUPP) with fallback to regular > pinning could maybe be moved into auto_attach_program(), so that > auto-attaching single programs can use the fallback too? > > Thanks, > Quentin If I understand correctly, can we just check link? as following: --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -1460,9 +1460,10 @@ static int do_run(int argc, char **argv) int err; link = bpf_program__attach(prog); - if (!link) - return -1; - + if (!link) { + p_info("Program %s attach failed", bpf_program__name(prog)); + return bpf_obj_pin(bpf_program__fd(prog), path); + } err = bpf_link__pin(link, path); if (err) { bpf_link__destroy(link); @@ -1499,9 +1500,6 @@ static int pathname_concat(const char *path, const char *name, char *buf) err = auto_attach_program(prog, buf); if (!err) continue; - if (errno == EOPNOTSUPP) - p_info("Program %s does not support autoattach", - bpf_program__name(prog)); else goto err_unpin_programs; } and the doc is modified as follows: If the program does not support autoattach, will do regular pin along with an info message such as "Program %s attach failed". If the *OBJ* contains multiple programs and **loadall** is used, if the program A in these programs does not support autoattach, the program A will do regular pin along with an info message, and continue to autoattach the next program. Thanks, Wang