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Date: Fri, 14 Oct 2022 14:38:54 +0800
From: wangyufen <wangyufen@...wei.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
CC: <quentin@...valent.com>, <ast@...nel.org>, <daniel@...earbox.net>,
<andrii@...nel.org>, <martin.lau@...ux.dev>, <song@...nel.org>,
<yhs@...com>, <john.fastabend@...il.com>, <kpsingh@...nel.org>,
<sdf@...gle.com>, <haoluo@...gle.com>, <jolsa@...nel.org>,
<davem@...emloft.net>, <kuba@...nel.org>, <hawk@...nel.org>,
<nathan@...nel.org>, <ndesaulniers@...gle.com>, <trix@...hat.com>,
<bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
<llvm@...ts.linux.dev>
Subject: Re: [bpf-next v8 1/3] bpftool: Add autoattach for bpf prog
load|loadall
在 2022/10/14 11:43, Andrii Nakryiko 写道:
> On Thu, Oct 13, 2022 at 7:24 PM wangyufen <wangyufen@...wei.com> wrote:
>>
>> 在 2022/10/14 3:47, Andrii Nakryiko 写道:
>>> On Mon, Oct 10, 2022 at 3:40 AM Wang Yufen <wangyufen@...wei.com> wrote:
>>>> Add autoattach optional to support one-step load-attach-pin_link.
>>>>
>>>> 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 <weiyongjun1@...wei.com>
>>>> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
>>>> ---
>>>> tools/bpf/bpftool/prog.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++--
>>>> 1 file changed, 76 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
>>>> index c81362a..8f3afce 100644
>>>> --- a/tools/bpf/bpftool/prog.c
>>>> +++ b/tools/bpf/bpftool/prog.c
>>>> @@ -1453,6 +1453,69 @@ 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) {
>>>> + p_info("Program %s does not support autoattach, falling back to pinning",
>>>> + 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);
>>>> + return err;
>>>> + }
>>> leaking link here, destroy it unconditionally. If pinning succeeded,
>>> you don't need to hold link's FD open anymore.
>> I got it, will change. Thanks！
>>
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int pathname_concat(const char *path, const char *name, char *buf)
>>> why you didn't do the same as in libbpf? Pass buffer size explicitly
>>> instead of assuming PATH_MAX
>> The pathname_concat function is invoked only in one place and is not a
>> general function here. So, not modified. Or, can I change the "pathname_concat"
>> of libbpf to "LIBBPF_API int libbpf_pathname_concat" and use the
>> libbpf_pathname_concat directly?
> no need to reuse libbpf's helper, but I do think it's cleaner to
> specify not just buffer pointer, but also it's size, just like you do
> with any other string buffer API (like snprintf)
OK, will change in v9 too. Thanks！
>
>>
>>>> +{
>>>> + 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)
>>>> + goto err_unpin_programs;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_unpin_programs:
>>>> + while ((prog = bpf_object__prev_program(obj, prog))) {
>>>> + if (pathname_concat(path, bpf_program__name(prog), buf))
>>>> + continue;
>>>> +
>>>> + bpf_program__unpin(prog, buf);
>>>> + }
>>>> +
>>>> + return err;
>>>> +}
>>>> +
>>>> static int load_with_options(int argc, char **argv, bool first_prog_only)
>>>> {
>>>> enum bpf_prog_type common_prog_type = BPF_PROG_TYPE_UNSPEC;
>>>> @@ -1464,6 +1527,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>>>> struct bpf_program *prog = NULL, *pos;
>>>> unsigned int old_map_fds = 0;
>>>> const char *pinmaps = NULL;
>>>> + bool auto_attach = false;
>>>> struct bpf_object *obj;
>>>> struct bpf_map *map;
>>>> const char *pinfile;
>>>> @@ -1583,6 +1647,9 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>>>> goto err_free_reuse_maps;
>>>>
>>>> pinmaps = GET_ARG();
>>>> + } else if (is_prefix(*argv, "autoattach")) {
>>>> + auto_attach = true;
>>>> + NEXT_ARG();
>>>> } else {
>>>> p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",
>>>> *argv);
>>>> @@ -1692,14 +1759,20 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>>>> goto err_close_obj;
>>>> }
>>>>
>>>> - err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
>>>> + if (auto_attach)
>>>> + err = auto_attach_program(prog, pinfile);
>>>> + else
>>>> + err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
>>>> if (err) {
>>>> p_err("failed to pin program %s",
>>>> bpf_program__section_name(prog));
>>>> goto err_close_obj;
>>>> }
>>>> } else {
>>>> - err = bpf_object__pin_programs(obj, pinfile);
>>>> + if (auto_attach)
>>>> + err = auto_attach_programs(obj, pinfile);
>>>> + else
>>>> + err = bpf_object__pin_programs(obj, pinfile);
>>>> if (err) {
>>>> p_err("failed to pin all programs");
>>>> goto err_close_obj;
>>>> @@ -2338,6 +2411,7 @@ static int do_help(int argc, char **argv)
>>>> " [type TYPE] [dev NAME] \\\n"
>>>> " [map { idx IDX | name NAME } MAP]\\\n"
>>>> " [pinmaps MAP_DIR]\n"
>>>> + " [autoattach]\n"
>>>> " %1$s %2$s attach PROG ATTACH_TYPE [MAP]\n"
>>>> " %1$s %2$s detach PROG ATTACH_TYPE [MAP]\n"
>>>> " %1$s %2$s run PROG \\\n"
>>>> --
>>>> 1.8.3.1
>>>>
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