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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/9/14 04:46, Andrii Nakryiko 写道: > On Fri, Sep 13, 2024 at 9:44 AM Tao Chen wrote: >> >> The commit "5902da6d8a52" set expected_attach_type again with >> filed of bpf_program after libpf_prepare_prog_load, which makes >> expected_attach_type = 0 no sense when kenrel not support the >> attach_type feature, so fix it. >> >> Fixes: 5902da6d8a52 ("libbpf: Add uprobe multi link support to bpf_program__attach_usdt") >> Suggested-by: Jiri Olsa >> Signed-off-by: Tao Chen >> --- >> tools/lib/bpf/libbpf.c | 6 ++---- >> 1 file changed, 2 insertions(+), 4 deletions(-) >> >> Change list: >> - v1 -> v2: >> - restore the original initialization way suggested by Jiri >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index 219facd0e66e..df2244397ba1 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -7353,7 +7353,7 @@ static int libbpf_prepare_prog_load(struct bpf_program *prog, >> >> /* special check for usdt to use uprobe_multi link */ >> if ((def & SEC_USDT) && kernel_supports(prog->obj, FEAT_UPROBE_MULTI_LINK)) >> - prog->expected_attach_type = BPF_TRACE_UPROBE_MULTI; >> + opts->expected_attach_type = BPF_TRACE_UPROBE_MULTI; >> > > Ok, took me a bit to understand what the issue is. But the above is > not quite correct, for the above case of setting > BPF_TRACE_UPROBE_MULTI we do want to record BPF_TRACE_UPROBE_MULTI in > prog->expected_attach_type, because user might want to query that > later. > > So I agree with the part of the fix below, but here I think we need > *both* update opts' and prog's expected_attach_type, so we will have: > > prog->expected_attach_type = BPF_TRACE_UPROBE_MULTI; > opts->expected_attach_type = BPF_TRACE_UPROBE_MULTI; > > pw-bot: cr > >> if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) { >> int btf_obj_fd = 0, btf_type_id = 0, err; >> @@ -7443,6 +7443,7 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog >> load_attr.attach_btf_id = prog->attach_btf_id; >> load_attr.kern_version = kern_version; >> load_attr.prog_ifindex = prog->prog_ifindex; >> + load_attr.expected_attach_type = prog->expected_attach_type; >> >> /* specify func_info/line_info only if kernel supports them */ >> if (obj->btf && btf__fd(obj->btf) >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) { >> @@ -7474,9 +7475,6 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog >> insns_cnt = prog->insns_cnt; >> } >> >> - /* allow prog_prepare_load_fn to change expected_attach_type */ >> - load_attr.expected_attach_type = prog->expected_attach_type; >> - >> if (obj->gen_loader) { >> bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name, >> license, insns, insns_cnt, &load_attr, >> -- >> 2.25.1 >> Hi, Andrii, thank you for your reply. I will send v3 as you suggested. -- Best Regards Dylane Chen