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 33149C433F5 for ; Mon, 10 Oct 2022 08:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231522AbiJJI6q (ORCPT ); Mon, 10 Oct 2022 04:58:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231129AbiJJI6n (ORCPT ); Mon, 10 Oct 2022 04:58:43 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32AFE6715C; Mon, 10 Oct 2022 01:58:42 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MmCPf51DlzHv53; Mon, 10 Oct 2022 16:53:42 +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; Mon, 10 Oct 2022 16:58:39 +0800 Message-ID: Date: Mon, 10 Oct 2022 16:58:39 +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> <0242ccfe-53e5-5b9d-9fd9-73fa8bd0d7a4@huawei.com> <5f26a827-0220-da23-f2fb-08f35ee7412e@isovalent.com> From: wangyufen In-Reply-To: <5f26a827-0220-da23-f2fb-08f35ee7412e@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 2022/10/10 16:40, Quentin Monnet 写道: > Sat Oct 08 2022 06:16:42 GMT+0100 ~ wangyufen >> 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: > Yes, this is exactly what I meant > >> --- 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", > p_info("Program %s does not support autoattach, falling back to pinning" > >> -                              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. > Not sure the "program A" designation helps too much, I'd simply write this: > > "If a program does not support autoattach, bpftool falls back to regular > pinning for that program instead." > > Which should be enough for both the "load" and "loadall" behaviours? I > wouldn't mention the help message in the docs (the p_info() won't show > up in the JSON output for example). I got it. Thanks! > > Looks good otherwise, thanks!