This patch adds a selftest for the `bpf_task_get_cgroup_id` kfunc. The test focuses on the use case of obtaining the cgroup ID of the previous task in a `sched_switch` tracepoint.
The selftest involves creating a test cgroup, attaching a BPF program that utilizes the `bpf_task_get_cgroup_id` during a `sched_switch` tracepoint, and validating that the obtained cgroup ID for the previous task matches the expected cgroup ID.
task_get_cgroup_id:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Jose Fernandez josef@netflix.com Reviewed-by: Tycho Andersen tycho@tycho.pizza --- .../bpf/prog_tests/task_get_cgroup_id.c | 58 +++++++++++++++++++ .../bpf/progs/test_task_get_cgroup_id.c | 30 ++++++++++ 2 files changed, 88 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_get_cgroup_id.c create mode 100644 tools/testing/selftests/bpf/progs/test_task_get_cgroup_id.c
diff --git a/tools/testing/selftests/bpf/prog_tests/task_get_cgroup_id.c b/tools/testing/selftests/bpf/prog_tests/task_get_cgroup_id.c new file mode 100644 index 000000000000..b8c4551195d3 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/task_get_cgroup_id.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright 2024 Netflix, Inc. + +#include <test_progs.h> +#include <cgroup_helpers.h> +#include "test_task_get_cgroup_id.skel.h" +#include <unistd.h> + +#define TEST_CGROUP "/test-task-get-cgroup-id/" + +void test_task_get_cgroup_id(void) +{ + struct test_task_get_cgroup_id *skel; + int err, fd; + pid_t pid; + __u64 cgroup_id, expected_cgroup_id; + const struct timespec req = { + .tv_sec = 1, + .tv_nsec = 0, + }; + + fd = test__join_cgroup(TEST_CGROUP); + if (!ASSERT_OK(fd < 0, "test_join_cgroup_TEST_CGROUP")) + return; + + skel = test_task_get_cgroup_id__open(); + if (!ASSERT_OK_PTR(skel, "test_task_get_cgroup_id__open")) + goto cleanup; + + err = test_task_get_cgroup_id__load(skel); + if (!ASSERT_OK(err, "test_task_get_cgroup_id__load")) + goto cleanup; + + err = test_task_get_cgroup_id__attach(skel); + if (!ASSERT_OK(err, "test_task_get_cgroup_id__attach")) + goto cleanup; + + pid = getpid(); + expected_cgroup_id = get_cgroup_id(TEST_CGROUP); + if (!ASSERT_GT(expected_cgroup_id, 0, "get_cgroup_id")) + goto cleanup; + + /* Trigger nanosleep to enter the sched_switch tracepoint */ + /* The previous task should be this process */ + syscall(__NR_nanosleep, &req, NULL); + + err = bpf_map_lookup_elem(bpf_map__fd(skel->maps.pid_to_cgid_map), &pid, + &cgroup_id); + + if (!ASSERT_OK(err, "bpf_map_lookup_elem")) + goto cleanup; + + ASSERT_EQ(cgroup_id, expected_cgroup_id, "cgroup_id"); + +cleanup: + test_task_get_cgroup_id__destroy(skel); + close(fd); +} diff --git a/tools/testing/selftests/bpf/progs/test_task_get_cgroup_id.c b/tools/testing/selftests/bpf/progs/test_task_get_cgroup_id.c new file mode 100644 index 000000000000..7e6bc008970f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_task_get_cgroup_id.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright 2024 Netflix, Inc. + +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +u64 bpf_task_get_cgroup_id(struct task_struct *task) __ksym; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 4096); + __type(key, __u32); + __type(value, __u64); +} pid_to_cgid_map SEC(".maps"); + +SEC("tp_btf/sched_switch") +int BPF_PROG(sched_switch, bool preempt, struct task_struct *prev, + struct task_struct *next) +{ + u32 pid = prev->pid; + u64 cgroup_id; + + cgroup_id = bpf_task_get_cgroup_id(prev); + bpf_map_update_elem(&pid_to_cgid_map, &pid, &cgroup_id, BPF_ANY); + + return 0; +} + +char _license[] SEC("license") = "GPL";