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AJvYcCUlCO++LV5w4qZzhv2dV3o1oVQIJCQLia7WLSZmNxP2IfCu5d5Pn62Zd/bfhAQQ59hxPHg=@vger.kernel.org, AJvYcCVyEmBgFkwdj2K9TUiFPyq57R9eGYp/43b10EAiolaP/pww8MUNKRHtgrEaT8o69GRW1v5Gbw1v1E1QI8Mp@vger.kernel.org X-Gm-Message-State: AOJu0YxxF4yrdMh5XIrclgS1vAzevPMvkbU9DgZoUX28G4C6/ekBDJOG 8Jx8b0Fp2lWl6nmosW/4EsY3tPpMrsaj3K82UcJmhJgX1E9Pf8iO X-Google-Smtp-Source: AGHT+IGiszi5u/D2JmGS2Ec+IKq8GqyWeaf3SUz5xBSUd1WMfC8UDHQC75fRy58VHrpkoUvgUKelHA== X-Received: by 2002:a17:903:986:b0:1fb:6294:2e35 with SMTP id d9443c01a7336-2076e4854f3mr94126525ad.50.1726240467968; Fri, 13 Sep 2024 08:14:27 -0700 (PDT) Received: from [192.168.50.122] ([117.147.91.189]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2076af25683sm29343895ad.17.2024.09.13.08.14.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Sep 2024 08:14:27 -0700 (PDT) Message-ID: <0e26d4c9-3e14-4bf9-85d3-86131e6a07f8@gmail.com> Date: Fri, 13 Sep 2024 23:14:17 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next] libbpf: Fix expected_attach_type set when kernel not support To: Jiri Olsa Cc: Andrii Nakryiko , Eduard Zingerman , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240913121627.153898-1-chen.dylane@gmail.com> From: Tao Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/9/13 21:48, Jiri Olsa 写道: > On Fri, Sep 13, 2024 at 08:16:27PM +0800, 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") >> Signed-off-by: Tao Chen >> --- >> tools/lib/bpf/libbpf.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index 219facd0e66e..9035edf763a3 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -7343,7 +7343,7 @@ static int libbpf_prepare_prog_load(struct bpf_program *prog, >> >> /* old kernels might not support specifying expected_attach_type */ >> if ((def & SEC_EXP_ATTACH_OPT) && !kernel_supports(prog->obj, FEAT_EXP_ATTACH_TYPE)) >> - opts->expected_attach_type = 0; >> + prog->expected_attach_type = 0; >> >> if (def & SEC_SLEEPABLE) >> opts->prog_flags |= BPF_F_SLEEPABLE; >> -- >> 2.25.1 >> > > good catch! thanks > > I can't remember why it was needed, perhaps we should go back to where it > was before? > > I'm guessing prog->expected_attach_type might not get updated properly and > that might cause issues, not sure > > thanks, > jirka > > > --- > 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; > > 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, Hi, Jiri, thank you for your reply. It looks better your way, i will send it in v2. -- Best Regards Dylane Chen