This is a follow up to: commit b8e3a87a627b ("bpf: Add crosstask check to __bpf_get_stack").

This test ensures that the task iterator only gets a single user stack (for the current task).

Signed-off-by: Jordan Rome linux@jordanrome.com --- tools/testing/selftests/bpf/prog_tests/bpf_iter.c | 2 ++ tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c | 5 +++++ 2 files changed, 7 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c index 4e02093c2cbe..618af9dfae9b 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c @@ -332,6 +332,8 @@ static void test_task_stack(void) do_dummy_read(skel->progs.dump_task_stack); do_dummy_read(skel->progs.get_task_user_stacks);

+ ASSERT_EQ(skel->bss->num_user_stacks, 1, "num_user_stacks"); + bpf_iter_task_stack__destroy(skel); }

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c index f2b8167b72a8..442f4ca39fd7 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c @@ -35,6 +35,8 @@ int dump_task_stack(struct bpf_iter__task *ctx) return 0; }

+int num_user_stacks = 0; + SEC("iter/task") int get_task_user_stacks(struct bpf_iter__task *ctx) { @@ -51,6 +53,9 @@ int get_task_user_stacks(struct bpf_iter__task *ctx) if (res <= 0) return 0;

+ /* Only one task, the current one, should succeed */ + ++num_user_stacks; + buf_sz += res;

/* If the verifier doesn't refine bpf_get_task_stack res, and instead