bpf, tests: add a test for htab lookup + update traversal

Add a test case to track behaviour when traversing and updating the
htab map. We recently used such traversal, so it's quite useful to
keep it as an example in selftests.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 93314524de0d033ded2a00d71bbf500a0afbd60e..79601c81e169c22650ae545b6a5fefb8323655ee 100644 (file)
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -239,6 +239,54 @@ static void test_hashmap_percpu(int task, void *data)
        close(fd);
 }
 
+static void test_hashmap_walk(int task, void *data)
+{
+       int fd, i, max_entries = 100000;
+       long long key, value, next_key;
+       bool next_key_valid = true;
+
+       fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
+                           max_entries, map_flags);
+       if (fd < 0) {
+               printf("Failed to create hashmap '%s'!\n", strerror(errno));
+               exit(1);
+       }
+
+       for (i = 0; i < max_entries; i++) {
+               key = i; value = key;
+               assert(bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST) == 0);
+       }
+
+       for (i = 0; bpf_map_get_next_key(fd, !i ? NULL : &key,
+                                        &next_key) == 0; i++) {
+               key = next_key;
+               assert(bpf_map_lookup_elem(fd, &key, &value) == 0);
+       }
+
+       assert(i == max_entries);
+
+       assert(bpf_map_get_next_key(fd, NULL, &key) == 0);
+       for (i = 0; next_key_valid; i++) {
+               next_key_valid = bpf_map_get_next_key(fd, &key, &next_key) == 0;
+               assert(bpf_map_lookup_elem(fd, &key, &value) == 0);
+               value++;
+               assert(bpf_map_update_elem(fd, &key, &value, BPF_EXIST) == 0);
+               key = next_key;
+       }
+
+       assert(i == max_entries);
+
+       for (i = 0; bpf_map_get_next_key(fd, !i ? NULL : &key,
+                                        &next_key) == 0; i++) {
+               key = next_key;
+               assert(bpf_map_lookup_elem(fd, &key, &value) == 0);
+               assert(value - 1 == key);
+       }
+
+       assert(i == max_entries);
+       close(fd);
+}
+
 static void test_arraymap(int task, void *data)
 {
        int key, next_key, fd;
@@ -464,6 +512,7 @@ static void test_map_stress(void)
        run_parallel(100, test_hashmap, NULL);
        run_parallel(100, test_hashmap_percpu, NULL);
        run_parallel(100, test_hashmap_sizes, NULL);
+       run_parallel(100, test_hashmap_walk, NULL);
 
        run_parallel(100, test_arraymap, NULL);
        run_parallel(100, test_arraymap_percpu, NULL);
@@ -549,6 +598,7 @@ static void run_all_tests(void)
 {
        test_hashmap(0, NULL);
        test_hashmap_percpu(0, NULL);
+       test_hashmap_walk(0, NULL);
 
        test_arraymap(0, NULL);
        test_arraymap_percpu(0, NULL);