Tests run in VM might be slow, so that children may exit before bpf
programs are loaded. SCX_GE(skel->bss->init_task_cnt, num_pre_forks)
would fail in this case.
For tests working in any env, use signals to control the lifetime of
children beyond bpf prog loading deterministically to get expected
results.
Signed-off-by: Ze Gao <zegao@xxxxxxxxxxx>
---
.../selftests/sched_ext/init_enable_count.c | 27 ++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/sched_ext/init_enable_count.c b/tools/testing/selftests/sched_ext/init_enable_count.c
index 97d45f1e5597..3b2c8ab8464f 100644
--- a/tools/testing/selftests/sched_ext/init_enable_count.c
+++ b/tools/testing/selftests/sched_ext/init_enable_count.c
@@ -31,6 +31,11 @@ open_load_prog(bool global)
return skel;
}
+/* Signal handler for children */
+void sigusr1_handler(int sig)
+{
+}
+
static enum scx_test_status run_test(bool global)
{
struct init_enable_count *skel;
@@ -39,9 +44,15 @@ static enum scx_test_status run_test(bool global)
int ret, i, status;
struct sched_param param = {};
pid_t pids[num_pre_forks];
+ sigset_t blocked_set;
skel = open_load_prog(global);
+ /* Block SIGUSR1 in parent, children will inherit this*/
+ sigemptyset(&blocked_set);
+ sigaddset(&blocked_set, SIGUSR1);
+ sigprocmask(SIG_BLOCK, &blocked_set, NULL);
+
/*
* Fork a bunch of children before we attach the scheduler so that we
* ensure (at least in practical terms) that there are more tasks that
@@ -52,7 +63,13 @@ static enum scx_test_status run_test(bool global)
pids[i] = fork();
SCX_FAIL_IF(pids[i] < 0, "Failed to fork child");
if (pids[i] == 0) {
- sleep(1);
+ signal(SIGUSR1, sigusr1_handler);
+ sigprocmask(SIG_UNBLOCK, &blocked_set, NULL);
+ /*
+ * Wait indefinitely for signal, will be interrupted
+ * by signal handler.
+ */
+ pause();
exit(0);
}
}
@@ -60,6 +77,13 @@ static enum scx_test_status run_test(bool global)
link = bpf_map__attach_struct_ops(skel->maps.init_enable_count_ops);
SCX_FAIL_IF(!link, "Failed to attach struct_ops");
+ /* Give children time to set up handlers */
+ sleep(1);
+
+ /* Send SIGUSR1 to all children */
+ for (int i = 0; i < num_pre_forks; i++)
+ kill(pids[i], SIGUSR1);
+
for (i = 0; i < num_pre_forks; i++) {
SCX_FAIL_IF(waitpid(pids[i], &status, 0) != pids[i],
"Failed to wait for pre-forked child\n");
@@ -69,6 +93,7 @@ static enum scx_test_status run_test(bool global)
}
bpf_link__destroy(link);
+ SCX_EQ(skel->bss->init_task_cnt, skel->bss->exit_task_cnt);
SCX_GE(skel->bss->init_task_cnt, num_pre_forks);
SCX_GE(skel->bss->exit_task_cnt, num_pre_forks);
--
2.41.1
