在 2024/9/14 04:46, Andrii Nakryiko 写道:
On Fri, Sep 13, 2024 at 9:44 AM Tao Chen <chen.dylane@xxxxxxxxx> 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 <jolsa@xxxxxxxxxx> Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx> --- 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: crif ((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
