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Message-ID: <fbb13238-d0e2-7b0f-8b7b-e4fb211bcaaf@huawei.com>
Date: Fri, 14 Oct 2022 10:24:39 +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 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?
>
>> +{
>> + 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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