diff --git a/tools/testing/selftests/bpf/prog_tests/perf_branches.c b/tools/testing/selftests/bpf/prog_tests/perf_branches.c index bc24f83339d6..1d51ec5f171a 100644 --- a/tools/testing/selftests/bpf/prog_tests/perf_branches.c +++ b/tools/testing/selftests/bpf/prog_tests/perf_branches.c @@ -15,6 +15,10 @@ static void check_good_sample(struct test_perf_branches *skel) int pbe_size = sizeof(struct perf_branch_entry); int duration = 0; + if (CHECK(!skel->bss->run_cnt, "invalid run_cnt", + "checked sample validity before prog run")) + return; + if (CHECK(!skel->bss->valid, "output not valid", "no valid sample from prog")) return; @@ -45,6 +49,10 @@ static void check_bad_sample(struct test_perf_branches *skel) int written_stack = skel->bss->written_stack_out; int duration = 0; + if (CHECK(!skel->bss->run_cnt, "invalid run_cnt", + "checked sample validity before prog run")) + return; + if (CHECK(!skel->bss->valid, "output not valid", "no valid sample from prog")) return; @@ -83,8 +91,12 @@ static void test_perf_branches_common(int perf_fd, err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set); if (CHECK(err, "set_affinity", "cpu #0, err %d\n", err)) goto out_destroy; - /* spin the loop for a while (random high number) */ - for (i = 0; i < 1000000; ++i) + + /* Spin the loop for a while by using a high iteration count, and by + * checking whether the specific run count marker has been explicitly + * incremented at least once by the backing perf_event BPF program. + */ + for (i = 0; i < 100000000 && !*(volatile int *)&skel->bss->run_cnt; ++i) ++j; test_perf_branches__detach(skel); diff --git a/tools/testing/selftests/bpf/progs/test_perf_branches.c b/tools/testing/selftests/bpf/progs/test_perf_branches.c index a1ccc831c882..05ac9410cd68 100644 --- a/tools/testing/selftests/bpf/progs/test_perf_branches.c +++ b/tools/testing/selftests/bpf/progs/test_perf_branches.c @@ -8,6 +8,7 @@ #include int valid = 0; +int run_cnt = 0; int required_size_out = 0; int written_stack_out = 0; int written_global_out = 0; @@ -24,6 +25,8 @@ int perf_branches(void *ctx) __u64 entries[4 * 3] = {0}; int required_size, written_stack, written_global; + ++run_cnt; + /* write to stack */ written_stack = bpf_read_branch_records(ctx, entries, sizeof(entries), 0); /* ignore spurious events */