selftests/bpf: Add test for unpinning htab with internal timer struct

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>
Link: https://lore.kernel.org/r/20251008102628.808045-3-kafai.wan@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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 (file)
index 0000000..16bd74b
--- /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 (file)
index 0000000..ae22793
--- /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");