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Wed, 24 Jun 2026 04:18:53 -0700 (PDT) From: Sun Jian To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, shuah@kernel.org, laoar.shao@gmail.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Sun Jian Subject: [PATCH bpf 2/2] selftests/bpf: Cover link info metadata on ENOSPC Date: Wed, 24 Jun 2026 19:18:37 +0800 Message-ID: <20260624111837.889209-2-sun.jian.kdev@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260624111837.889209-1-sun.jian.kdev@gmail.com> References: <20260624111837.889209-1-sun.jian.kdev@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a perf event tracepoint link info check with a one-byte tp_name buffer. The query is expected to return -ENOSPC because the nested name buffer is too small, but it should still report the top-level link type, perf event type, cookie, and real tp_name length. Before the fix, bpf_link_get_info_by_fd() returned -ENOSPC but did not copy the top-level bpf_link_info back to userspace, leaving info.type as zero. Signed-off-by: Sun Jian --- .../selftests/bpf/prog_tests/fill_link_info.c | 35 +++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c index f589eefbf9fb..95132c80b3b9 100644 --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c @@ -126,6 +126,37 @@ static int verify_perf_link_info(int fd, enum bpf_perf_event_type type, long add return err; } +static int verify_perf_tp_link_info_enospc(int fd) +{ + struct bpf_link_info info; + __u32 len = sizeof(info); + char buf[1] = {}; + int err; + + memset(&info, 0, sizeof(info)); + info.perf_event.tracepoint.tp_name = ptr_to_u64(buf); + info.perf_event.tracepoint.name_len = sizeof(buf); + + err = bpf_link_get_info_by_fd(fd, &info, &len); + if (!ASSERT_EQ(err, -ENOSPC, "get_link_info_enospc")) + return -1; + + if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "link_type_enospc")) + return -1; + if (!ASSERT_EQ(info.perf_event.type, BPF_PERF_EVENT_TRACEPOINT, "perf_type_enospc")) + return -1; + if (!ASSERT_EQ(info.perf_event.tracepoint.name_len, strlen(TP_NAME) + 1, + "tp_name_len_enospc")) + return -1; + if (!ASSERT_EQ(info.perf_event.tracepoint.cookie, PERF_EVENT_COOKIE, + "tp_cookie_enospc")) + return -1; + if (!ASSERT_EQ(buf[0], '\0', "short_tp_name_nul")) + return -1; + + return 0; +} + static void kprobe_fill_invalid_user_buffer(int fd) { struct bpf_link_info info; @@ -200,6 +231,10 @@ static void test_tp_fill_link_info(struct test_fill_link_info *skel) link_fd = bpf_link__fd(link); err = verify_perf_link_info(link_fd, BPF_PERF_EVENT_TRACEPOINT, 0, 0, 0); ASSERT_OK(err, "verify_perf_link_info"); + + err = verify_perf_tp_link_info_enospc(link_fd); + ASSERT_OK(err, "verify_perf_tp_link_info_enospc"); + bpf_link__destroy(link); } -- 2.43.0