selftests/bpf: Stress test attaching a BPF prog to another BPF prog

Add a test that invokes a BPF prog in a loop, while concurrently
attaching and detaching another BPF prog to and from it. This helps
identifying race conditions in bpf_arch_text_poke().

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250716194524.48109-3-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c
index 8100509e561b2ce2609243f29699b677de3eb5f1..0ffa01d54ce219c9e6cbe97eea0e2d3bb64d19d8 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c
@@ -149,3 +149,70 @@ close_prog:
        fentry_recursive_target__destroy(target_skel);
        fentry_recursive__destroy(tracing_skel);
 }
+
+static void *fentry_target_test_run(void *arg)
+{
+       for (;;) {
+               int prog_fd = __atomic_load_n((int *)arg, __ATOMIC_SEQ_CST);
+               LIBBPF_OPTS(bpf_test_run_opts, topts);
+               int err;
+
+               if (prog_fd == -1)
+                       break;
+               err = bpf_prog_test_run_opts(prog_fd, &topts);
+               if (!ASSERT_OK(err, "fentry_target test_run"))
+                       break;
+       }
+
+       return NULL;
+}
+
+void test_fentry_attach_stress(void)
+{
+       struct fentry_recursive_target *target_skel = NULL;
+       struct fentry_recursive *tracing_skel = NULL;
+       struct bpf_program *prog;
+       int err, i, tgt_prog_fd;
+       pthread_t thread;
+
+       target_skel = fentry_recursive_target__open_and_load();
+       if (!ASSERT_OK_PTR(target_skel,
+                          "fentry_recursive_target__open_and_load"))
+               goto close_prog;
+       tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
+       err = pthread_create(&thread, NULL,
+                            fentry_target_test_run, &tgt_prog_fd);
+       if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
+               goto close_prog;
+
+       for (i = 0; i < 1000; i++) {
+               tracing_skel = fentry_recursive__open();
+               if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
+                       goto stop_thread;
+
+               prog = tracing_skel->progs.recursive_attach;
+               err = bpf_program__set_attach_target(prog, tgt_prog_fd,
+                                                    "fentry_target");
+               if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
+                       goto stop_thread;
+
+               err = fentry_recursive__load(tracing_skel);
+               if (!ASSERT_OK(err, "fentry_recursive__load"))
+                       goto stop_thread;
+
+               err = fentry_recursive__attach(tracing_skel);
+               if (!ASSERT_OK(err, "fentry_recursive__attach"))
+                       goto stop_thread;
+
+               fentry_recursive__destroy(tracing_skel);
+               tracing_skel = NULL;
+       }
+
+stop_thread:
+       __atomic_store_n(&tgt_prog_fd, -1, __ATOMIC_SEQ_CST);
+       err = pthread_join(thread, NULL);
+       ASSERT_OK(err, "pthread_join");
+close_prog:
+       fentry_recursive__destroy(tracing_skel);
+       fentry_recursive_target__destroy(target_skel);
+}