[RFC v2 PATCH bpf-next 4/4] selftests/bpf: test map percpu stats

Anton Protopopov
2023-06-22T09:57:22Z

Add a new map test, map_percpu_stats.c, which is checking the correctness of
map's percpu elements counters. For supported maps the test upserts a number
of elements, checks the correctness of the counters, then deletes all the
elements and checks again that the counters sum drops down to zero.

The following map types are tested:

* BPF_MAP_TYPE_HASH, BPF_F_NO_PREALLOC
* BPF_MAP_TYPE_PERCPU_HASH, BPF_F_NO_PREALLOC
* BPF_MAP_TYPE_HASH,
* BPF_MAP_TYPE_PERCPU_HASH,
* BPF_MAP_TYPE_LRU_HASH
* BPF_MAP_TYPE_LRU_PERCPU_HASH

Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
---
.../bpf/map_tests/map_percpu_stats.c | 336 ++++++++++++++++++
.../selftests/bpf/progs/map_percpu_stats.c | 24 ++
2 files changed, 360 insertions(+)
create mode 100644 tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
create mode 100644 tools/testing/selftests/bpf/progs/map_percpu_stats.c

diff --git a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
new file mode 100644
index 000000000000..015be10c5ef4
--- /dev/null
+++ b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Isovalent */
+
+#include <errno.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include <bpf_util.h>
+#include <test_maps.h>
+
+#include "map_percpu_stats.skel.h"
+
+#define MAX_ENTRIES 16384
+#define N_THREADS 37
+
+#define MAX_MAP_KEY_SIZE 4
+
+static void map_info(int map_fd, struct bpf_map_info *info)
+{
+ __u32 len = sizeof(*info);
+ int ret;
+
+ memset(info, 0, sizeof(*info));
+
+ ret = bpf_obj_get_info_by_fd(map_fd, info, &len);
+ CHECK(ret < 0, "bpf_obj_get_info_by_fd", "error: %s\n", strerror(errno));
+}
+
+static const char *map_type_to_s(__u32 type)
+{
+ switch (type) {
+ case BPF_MAP_TYPE_HASH:
+ return "HASH";
+ case BPF_MAP_TYPE_PERCPU_HASH:
+ return "PERCPU_HASH";
+ case BPF_MAP_TYPE_LRU_HASH:
+ return "LRU_HASH";
+ case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+ return "LRU_PERCPU_HASH";
+ default:
+ return "<define-me>";
+ }
+}
+
+/* Map i -> map-type-specific-key */
+static void *map_key(__u32 type, __u32 i)
+{
+ static __thread __u8 key[MAX_MAP_KEY_SIZE];
+
+ *(__u32 *)key = i;
+ return key;
+}
+
+static __u32 map_count_elements(__u32 type, int map_fd)
+{
+ void *key = map_key(type, -1);
+ int n = 0;
+
+ while (!bpf_map_get_next_key(map_fd, key, key))
+ n++;
+ return n;
+}
+
+static void delete_all_elements(__u32 type, int map_fd)
+{
+ void *key = map_key(type, -1);
+ void *keys;
+ int n = 0;
+ int ret;
+
+ keys = calloc(MAX_MAP_KEY_SIZE, MAX_ENTRIES);
+ CHECK(!keys, "calloc", "error: %s\n", strerror(errno));
+
+ for (; !bpf_map_get_next_key(map_fd, key, key); n++)
+ memcpy(keys + n*MAX_MAP_KEY_SIZE, key, MAX_MAP_KEY_SIZE);
+
+ while (--n >= 0) {
+ ret = bpf_map_delete_elem(map_fd, keys + n*MAX_MAP_KEY_SIZE);
+ CHECK(ret < 0, "bpf_map_delete_elem", "error: %s\n", strerror(errno));
+ }
+}
+
+static bool is_lru(__u32 map_type)
+{
+ return map_type == BPF_MAP_TYPE_LRU_HASH ||
+ map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
+}
+
+struct upsert_opts {
+ __u32 map_type;
+ int map_fd;
+ __u32 n;
+};
+
+static void *patch_map_thread(void *arg)
+{
+ struct upsert_opts *opts = arg;
+ void *key;
+ int val;
+ int ret;
+ int i;
+
+ for (i = 0; i < opts->n; i++) {
+ key = map_key(opts->map_type, i);
+ val = rand();
+ ret = bpf_map_update_elem(opts->map_fd, key, &val, 0);
+ CHECK(ret < 0, "bpf_map_update_elem", "error: %s\n", strerror(errno));
+ }
+ return NULL;
+}
+
+static void upsert_elements(struct upsert_opts *opts)
+{
+ pthread_t threads[N_THREADS];
+ int ret;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(threads); i++) {
+ ret = pthread_create(&i[threads], NULL, patch_map_thread, opts);
+ CHECK(ret != 0, "pthread_create", "error: %s\n", strerror(ret));
+ }
+
+ for (i = 0; i < ARRAY_SIZE(threads); i++) {
+ ret = pthread_join(i[threads], NULL);
+ CHECK(ret != 0, "pthread_join", "error: %s\n", strerror(ret));
+ }
+}
+
+static __u32 read_cur_elements(int iter_fd)
+{
+ char buf[64];
+ ssize_t n;
+ __u32 ret;
+
+ n = read(iter_fd, buf, sizeof(buf)-1);
+ CHECK(n <= 0, "read", "error: %s\n", strerror(errno));
+ buf[n] = '\0';
+
+ errno = 0;
+ ret = (__u32)strtol(buf, NULL, 10);
+ CHECK(errno != 0, "strtol", "error: %s\n", strerror(errno));
+
+ return ret;
+}
+
+static __u32 get_cur_elements(int map_id)
+{
+ LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+ union bpf_iter_link_info linfo;
+ struct map_percpu_stats *skel;
+ struct bpf_link *link;
+ int iter_fd;
+ int ret;
+
+ opts.link_info = &linfo;
+ opts.link_info_len = sizeof(linfo);
+
+ skel = map_percpu_stats__open();
+ CHECK(skel == NULL, "map_percpu_stats__open", "error: %s", strerror(errno));
+
+ skel->bss->target_id = map_id;
+
+ ret = map_percpu_stats__load(skel);
+ CHECK(ret != 0, "map_percpu_stats__load", "error: %s", strerror(errno));
+
+ link = bpf_program__attach_iter(skel->progs.dump_bpf_map, &opts);
+ CHECK(!link, "bpf_program__attach_iter", "error: %s\n", strerror(errno));
+
+ iter_fd = bpf_iter_create(bpf_link__fd(link));
+ CHECK(iter_fd < 0, "bpf_iter_create", "error: %s\n", strerror(errno));
+
+ return read_cur_elements(iter_fd);
+}
+
+static void __test(int map_fd)
+{
+ __u32 n = MAX_ENTRIES - 1000;
+ __u32 real_current_elements;
+ __u32 iter_current_elements;
+ struct upsert_opts opts = {
+ .map_fd = map_fd,
+ .n = n,
+ };
+ struct bpf_map_info info;
+
+ map_info(map_fd, &info);
+ opts.map_type = info.type;
+
+ /*
+ * Upsert keys [0, n) under some competition: with random values from
+ * N_THREADS threads
+ */
+ upsert_elements(&opts);
+
+ /*
+ * The sum of percpu elements counters for all hashtable-based maps
+ * should be equal to the number of elements present in the map. For
+ * non-lru maps this number should be the number n of upserted
+ * elements. For lru maps some elements might have been evicted. Check
+ * that all numbers make sense
+ */
+ map_info(map_fd, &info);
+ real_current_elements = map_count_elements(info.type, map_fd);
+ if (!is_lru(info.type))
+ CHECK(n != real_current_elements, "map_count_elements",
+ "real_current_elements(%u) != expected(%u)\n", real_current_elements, n);
+
+ iter_current_elements = get_cur_elements(info.id);
+ CHECK(iter_current_elements != real_current_elements, "get_cur_elements",
+ "iter_current_elements=%u, expected %u (map_type=%s,map_flags=%08x)\n",
+ iter_current_elements, real_current_elements, map_type_to_s(info.type), info.map_flags);
+
+ /*
+ * Cleanup the map and check that all elements are actually gone and
+ * that the sum of percpu elements counters is back to 0 as well
+ */
+ delete_all_elements(info.type, map_fd);
+ map_info(map_fd, &info);
+ real_current_elements = map_count_elements(info.type, map_fd);
+ CHECK(real_current_elements, "map_count_elements",
+ "expected real_current_elements=0, got %u", real_current_elements);
+
+ iter_current_elements = get_cur_elements(info.id);
+ CHECK(iter_current_elements != 0, "get_cur_elements",
+ "iter_current_elements=%u, expected 0 (map_type=%s,map_flags=%08x)\n",
+ iter_current_elements, map_type_to_s(info.type), info.map_flags);
+
+ close(map_fd);
+}
+
+static int map_create_opts(__u32 type, const char *name,
+ struct bpf_map_create_opts *map_opts,
+ __u32 key_size, __u32 val_size)
+{
+ int map_fd;
+
+ map_fd = bpf_map_create(type, name, key_size, val_size, MAX_ENTRIES, map_opts);
+ CHECK(map_fd < 0, "bpf_map_create()", "error:%s (name=%s)\n",
+ strerror(errno), name);
+
+ return map_fd;
+}
+
+static int map_create(__u32 type, const char *name, struct bpf_map_create_opts *map_opts)
+{
+ return map_create_opts(type, name, map_opts, sizeof(int), sizeof(int));
+}
+
+static int create_hash(void)
+{
+ struct bpf_map_create_opts map_opts = {
+ .sz = sizeof(map_opts),
+ .map_flags = BPF_F_NO_PREALLOC,
+ };
+
+ return map_create(BPF_MAP_TYPE_HASH, "hash", &map_opts);
+}
+
+static int create_percpu_hash(void)
+{
+ struct bpf_map_create_opts map_opts = {
+ .sz = sizeof(map_opts),
+ .map_flags = BPF_F_NO_PREALLOC,
+ };
+
+ return map_create(BPF_MAP_TYPE_PERCPU_HASH, "percpu_hash", &map_opts);
+}
+
+static int create_hash_prealloc(void)
+{
+ return map_create(BPF_MAP_TYPE_HASH, "hash", NULL);
+}
+
+static int create_percpu_hash_prealloc(void)
+{
+ return map_create(BPF_MAP_TYPE_PERCPU_HASH, "percpu_hash_prealloc", NULL);
+}
+
+static int create_lru_hash(void)
+{
+ return map_create(BPF_MAP_TYPE_LRU_HASH, "lru_hash", NULL);
+}
+
+static int create_percpu_lru_hash(void)
+{
+ return map_create(BPF_MAP_TYPE_LRU_PERCPU_HASH, "lru_hash_percpu", NULL);
+}
+
+static void map_percpu_stats_hash(void)
+{
+ __test(create_hash());
+ printf("test_%s:PASS\n", __func__);
+}
+
+static void map_percpu_stats_percpu_hash(void)
+{
+ __test(create_percpu_hash());
+ printf("test_%s:PASS\n", __func__);
+}
+
+static void map_percpu_stats_hash_prealloc(void)
+{
+ __test(create_hash_prealloc());
+ printf("test_%s:PASS\n", __func__);
+}
+
+static void map_percpu_stats_percpu_hash_prealloc(void)
+{
+ __test(create_percpu_hash_prealloc());
+ printf("test_%s:PASS\n", __func__);
+}
+
+static void map_percpu_stats_lru_hash(void)
+{
+ __test(create_lru_hash());
+ printf("test_%s:PASS\n", __func__);
+}
+
+static void map_percpu_stats_percpu_lru_hash(void)
+{
+ __test(create_percpu_lru_hash());
+ printf("test_%s:PASS\n", __func__);
+}
+
+void test_map_percpu_stats(void)
+{
+ map_percpu_stats_hash();
+ map_percpu_stats_percpu_hash();
+ map_percpu_stats_hash_prealloc();
+ map_percpu_stats_percpu_hash_prealloc();
+ map_percpu_stats_lru_hash();
+ map_percpu_stats_percpu_lru_hash();
+}
diff --git a/tools/testing/selftests/bpf/progs/map_percpu_stats.c b/tools/testing/selftests/bpf/progs/map_percpu_stats.c
new file mode 100644
index 000000000000..eeb486ef724f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/map_percpu_stats.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Isovalent */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+__u32 target_id;
+
+__s64 bpf_map_sum_elements_counter(struct bpf_map *map) __ksym;
+
+SEC("iter/bpf_map")
+int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
+{
+ struct seq_file *seq = ctx->meta->seq;
+ struct bpf_map *map = ctx->map;
+
+ if (map && map->id == target_id)
+ BPF_SEQ_PRINTF(seq, "%lld", bpf_map_sum_elements_counter(map));
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.34.1