From: Leon Hwang <leon.hwang@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Shuah Khan <shuah@kernel.org>, Leon Hwang <leon.hwang@linux.dev>,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH bpf-next v2] selftests/bpf: Avoid flaky resize value test for percpu data
Date: Tue, 18 Aug 2026 23:32:01 +0800 [thread overview]
Message-ID: <20260818153202.90714-1-leon.hwang@linux.dev> (raw)
The bpf_map__set_value_size() test for percpu data relies on the tail
'cpu_id' field in the ".percpu" map. The test would fail, when 'cpu_id' is
not the last field in the map.
To avoid the flaky test, factor out a subtest to use a dedicated
".percpu.arr" map that only has one field 'int arr[1]' to ensure that
bpf_map__set_value_size() won't fail on 4K page systems.
And, drop 'args' in test_percpu_data_on_cpus(), which isn't used in bpf
prog side.
And, enhance the test to cover 'set' and 'nums[6]'.
Fixes: 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu data")
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
v1 -> v2:
* Factor out a subtest to test bpf_map__set_value_size().
* Run the new subtest only on 4K page systems. (Sashiko)
* v1: https://lore.kernel.org/bpf/20260814173206.93082-5-leon.hwang@linux.dev/
---
.../bpf/prog_tests/global_data_init.c | 86 ++++++++++++++-----
.../bpf/progs/test_global_percpu_data.c | 10 ++-
2 files changed, 70 insertions(+), 26 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
index 5671c31085cd..2b69290bcc3e 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
@@ -68,12 +68,9 @@ static void test_percpu_data_on_cpus(struct bpf_map *map, int map_fd, int prog_f
{
struct test_global_percpu_data__percpu *data = NULL;
int i, err, key = 0, num_online, run = 0;
- __u64 args[2] = {0x1234ULL, 0x5678ULL};
size_t data_sz;
bool *online;
LIBBPF_OPTS(bpf_test_run_opts, topts,
- .ctx_in = args,
- .ctx_size_in = sizeof(args),
.flags = BPF_F_TEST_RUN_ON_CPU,
);
@@ -81,7 +78,7 @@ static void test_percpu_data_on_cpus(struct bpf_map *map, int map_fd, int prog_f
if (!ASSERT_OK(err, "parse_cpu_mask_file"))
return;
- data_sz = map ? bpf_map__value_size(map) : sizeof(*data);
+ data_sz = sizeof(*data);
data = calloc(1, data_sz);
if (!ASSERT_OK_PTR(data, "calloc percpu data"))
goto out;
@@ -109,7 +106,7 @@ static void test_percpu_data_on_cpus(struct bpf_map *map, int map_fd, int prog_f
break;
ASSERT_EQ(*runp, ++run, "run");
- ASSERT_EQ(data->cpu_id[0], i, "cpu_id");
+ ASSERT_EQ(data->cpu_id, i, "cpu_id");
ASSERT_EQ(data->data, 1, "data");
ASSERT_TRUE(data->set, "set");
ASSERT_EQ(data->nums[6], 0xc0de, "nums[6]");
@@ -127,7 +124,6 @@ static void test_global_percpu_data_init(void)
{
struct test_global_percpu_data__percpu init_value = {};
struct test_global_percpu_data__percpu *init_data;
- const __u32 desired_sz = sysconf(_SC_PAGE_SIZE);
struct test_global_percpu_data *skel = NULL;
size_t init_data_sz;
struct bpf_map *map;
@@ -163,9 +159,11 @@ static void test_global_percpu_data_init(void)
if (!ASSERT_EQ(bpf_map__type(map), BPF_MAP_TYPE_PERCPU_ARRAY, "bpf_map__type"))
goto out;
+ init_value.set = 1;
init_value.data = 2;
init_value.nums[6] = -1;
init_value.struct_data.i = 2;
+ init_value.struct_data.set = 1;
init_value.struct_data.nums[6] = -1;
err = bpf_map__set_initial_value(map, &init_value, sizeof(init_value));
if (!ASSERT_OK(err, "bpf_map__set_initial_value"))
@@ -177,35 +175,24 @@ static void test_global_percpu_data_init(void)
ASSERT_EQ(init_data->data, init_value.data, "init_value data");
ASSERT_EQ(init_data->set, init_value.set, "init_value set");
+ ASSERT_EQ(init_data->nums[6], init_value.nums[6], "init_value nums[6]");
ASSERT_EQ(init_data->struct_data.i, init_value.struct_data.i, "init_value struct_data.i");
+ ASSERT_EQ(init_data->struct_data.set, init_value.struct_data.set,
+ "init_value struct_data.set");
ASSERT_EQ(init_data->struct_data.nums[6], init_value.struct_data.nums[6],
"init_value struct_data.nums[6]");
ASSERT_EQ(init_data_sz, sizeof(init_value), "init_value size");
ASSERT_EQ((void *) init_data, (void *) skel->percpu, "skel->percpu eq init_data");
ASSERT_EQ(skel->percpu->data, init_value.data, "skel->percpu->data");
ASSERT_EQ(skel->percpu->set, init_value.set, "skel->percpu->set");
+ ASSERT_EQ(skel->percpu->nums[6], init_value.nums[6], "skel->percpu->nums[6]");
ASSERT_EQ(skel->percpu->struct_data.i, init_value.struct_data.i,
"skel->percpu->struct_data.i");
+ ASSERT_EQ(skel->percpu->struct_data.set, init_value.struct_data.set,
+ "skel->percpu->struct_data.set");
ASSERT_EQ(skel->percpu->struct_data.nums[6], init_value.struct_data.nums[6],
"skel->percpu->struct_data.nums[6]");
- ASSERT_GT(desired_sz, sizeof(init_value), "desired_sz");
- err = bpf_map__set_value_size(map, desired_sz);
- if (!ASSERT_OK(err, "bpf_map__set_value_size"))
- goto out;
- if (!ASSERT_EQ(bpf_map__value_size(map), desired_sz, "percpu value size"))
- goto out;
- if (!ASSERT_NEQ(bpf_map__btf_value_type_id(map), 0, "percpu BTF value type"))
- goto out;
-
- init_data = bpf_map__initial_value(map, &init_data_sz);
- if (!ASSERT_OK_PTR(init_data, "resized bpf_map__initial_value"))
- goto out;
- if (!ASSERT_EQ(init_data_sz, desired_sz, "resized initial value size"))
- goto out;
- if (!ASSERT_EQ(init_data->data, init_value.data, "resized initial value data"))
- goto out;
-
err = test_global_percpu_data__load(skel);
if (!ASSERT_OK(err, "test_global_percpu_data__load"))
goto out;
@@ -236,6 +223,57 @@ static void test_global_percpu_data_lskel(void)
test_global_percpu_data_lskel__destroy(lskel);
}
+#define PAGE_SIZE 4096
+
+static void test_global_percpu_data_map_resize(void)
+{
+ const __u32 desired_sz = sysconf(_SC_PAGE_SIZE) * 2;
+ struct test_global_percpu_data *skel;
+ const int arr_value = -1;
+ struct bpf_map *map;
+ int err, prog_fd;
+ size_t data_sz;
+
+ if (sysconf(_SC_PAGE_SIZE) != PAGE_SIZE) {
+ test__skip();
+ return;
+ }
+
+ skel = test_global_percpu_data__open();
+ if (!ASSERT_OK_PTR(skel, "test_global_percpu_data__open"))
+ return;
+
+ map = skel->maps.percpu_arr;
+ skel->percpu_arr->arr[0] = arr_value;
+ err = bpf_map__set_value_size(map, desired_sz);
+ if (!ASSERT_OK(err, "bpf_map__set_value_size"))
+ goto out;
+ if (!ASSERT_EQ(bpf_map__value_size(map), desired_sz, "bpf_map__value_size"))
+ goto out;
+ if (!ASSERT_NEQ(bpf_map__btf_value_type_id(map), 0, "bpf_map__btf_value_type_id"))
+ goto out;
+
+ skel->percpu_arr = bpf_map__initial_value(map, &data_sz);
+ if (!ASSERT_EQ(data_sz, desired_sz, "data_sz"))
+ goto out;
+ if (!ASSERT_OK_PTR(skel->percpu_arr, "skel->percpu_arr"))
+ goto out;
+ if (!ASSERT_EQ(skel->percpu_arr->arr[0], arr_value, "arr[0]"))
+ goto out;
+
+ err = test_global_percpu_data__load(skel);
+ if (!ASSERT_OK(err, "test_global_percpu_data__load"))
+ goto out;
+
+ map = skel->maps.percpu;
+ prog_fd = bpf_program__fd(skel->progs.update_percpu_data);
+ test_percpu_data_on_cpus(map, bpf_map__fd(map), prog_fd, &skel->bss->run);
+ ASSERT_EQ(skel->bss->arr_sum, arr_value * skel->bss->run, "arr_sum");
+
+out:
+ test_global_percpu_data__destroy(skel);
+}
+
static int create_rdonly_percpu_array(void)
{
LIBBPF_OPTS(bpf_map_create_opts, map_opts,
@@ -388,6 +426,8 @@ void test_global_percpu_data(void)
test_global_percpu_data_init();
if (test__start_subtest("lskel"))
test_global_percpu_data_lskel();
+ if (test__start_subtest("map_resize"))
+ test_global_percpu_data_map_resize();
if (test__start_subtest("rdonly_direct_read"))
test_global_percpu_data_rdonly_direct_read();
if (test__start_subtest("rdonly_direct_write"))
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
index 5dc21b3b4cb5..2765cd46e9af 100644
--- a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
@@ -8,9 +8,12 @@ int loong SEC(".percpu.looooooooong");
int data3 SEC(".data.percpu");
int data2 SEC(".percpu.data");
+/* Used for testing bpf_map__set_value_size(). */
+int arr[1] SEC(".percpu.arr");
+int arr_sum;
+
int run;
-/* cpu_id as array to verify map value resizing. */
-int cpu_id[1] SEC(".percpu");
+int cpu_id SEC(".percpu");
int data SEC(".percpu") = -1;
int nums[7] SEC(".percpu");
bool set SEC(".percpu") = false;
@@ -34,7 +37,8 @@ int update_percpu_data(void *ctx)
data = 1;
run++;
set = true;
- cpu_id[0] = bpf_get_smp_processor_id();
+ cpu_id = bpf_get_smp_processor_id();
+ arr_sum += arr[0];
return 0;
}
--
2.55.0
next reply other threads:[~2026-08-18 15:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-18 15:32 Leon Hwang [this message]
2026-08-18 16:15 ` [PATCH bpf-next v2] selftests/bpf: Avoid flaky resize value test for percpu data bot+bpf-ci
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