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SubjectRe: [bpf-next v6 1/3] bpftool: Add auto_attach for bpf prog load|loadall
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在 2022/9/26 18:46, Quentin Monnet 写道:
> Sat Sep 24 2022 11:13:48 GMT+0100 (British Summer Time) ~ Wang Yufen
> <wangyufen@huawei.com>
>> Add auto_attach 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@huawei.com>
>> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
>> ---
>> 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 | 76 ++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 74 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
>> index c81362a001ba..b1cbd06dee19 100644
>> --- a/tools/bpf/bpftool/prog.c
>> +++ b/tools/bpf/bpftool/prog.c
>> @@ -1453,6 +1453,67 @@ get_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
>> 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 && errno != EOPNOTSUPP)
>> + goto err_unpin_programs;
> If I read the above correctly, we skip entirely programs that couldn't
> be auto-attached. I'm not sure what Andrii had in mind exactly, but it
> would make sense to me to fallback to regular program pinning if the
> program couldn't be attached/linked, so we still keep it loaded in the
> kernel after bpftool exits. Probably with a p_info() message to let
> users know?

Thanks for your comment.
I agree with you.
add in v7.

>
>> + }
>> +
>> + 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;
>> +}

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