[PATCH bpf v3 2/2] selftests/bpf: Add test for unpinning htab with internal timer struct

KaFai Wan
2025-10-08T10:26:57Z

Add test to verify that unpinning hash tables containing internal timer
structures does not trigger context warnings.

Each subtest (timer_prealloc and timer_no_prealloc) can trigger the
context warning when unpinning, but the warning cannot be triggered
twice within a short time interval (a HZ), which is expected behavior.

Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
---
.../selftests/bpf/prog_tests/pinning_htab.c | 36 +++++++++++++++++++
.../selftests/bpf/progs/test_pinning_htab.c | 25 +++++++++++++
2 files changed, 61 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/pinning_htab.c
create mode 100644 tools/testing/selftests/bpf/progs/test_pinning_htab.c

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning_htab.c b/tools/testing/selftests/bpf/prog_tests/pinning_htab.c
new file mode 100644
index 000000000000..16bd74be3dbe
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/pinning_htab.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "test_pinning_htab.skel.h"
+
+static void unpin_map(const char *map_name, const char *pin_path)
+{
+ struct test_pinning_htab *skel;
+ struct bpf_map *map;
+ int err;
+
+ skel = test_pinning_htab__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
+ return;
+
+ map = bpf_object__find_map_by_name(skel->obj, map_name);
+ if (!ASSERT_OK_PTR(map, "bpf_object__find_map_by_name"))
+ goto out;
+
+ err = bpf_map__pin(map, pin_path);
+ if (!ASSERT_OK(err, "bpf_map__pin"))
+ goto out;
+
+ err = bpf_map__unpin(map, pin_path);
+ ASSERT_OK(err, "bpf_map__unpin");
+out:
+ test_pinning_htab__destroy(skel);
+}
+
+void test_pinning_htab(void)
+{
+ if (test__start_subtest("timer_prealloc"))
+ unpin_map("timer_prealloc", "/sys/fs/bpf/timer_prealloc");
+ if (test__start_subtest("timer_no_prealloc"))
+ unpin_map("timer_no_prealloc", "/sys/fs/bpf/timer_no_prealloc");
+}
diff --git a/tools/testing/selftests/bpf/progs/test_pinning_htab.c b/tools/testing/selftests/bpf/progs/test_pinning_htab.c
new file mode 100644
index 000000000000..ae227930c73c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_pinning_htab.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct timer_val {
+ struct bpf_timer timer;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, __u32);
+ __type(value, struct timer_val);
+ __uint(max_entries, 1);
+} timer_prealloc SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, __u32);
+ __type(value, struct timer_val);
+ __uint(max_entries, 1);
+ __uint(map_flags, BPF_F_NO_PREALLOC);
+} timer_no_prealloc SEC(".maps");
--
2.43.0