Documentation/bpf/map_hash.rst

16 purpose hash map storage. Both the key and the value can be structs,
19 The kernel is responsible for allocating and freeing key/value pairs, up
24 ``BPF_MAP_TYPE_PERCPU_HASH`` provides a separate value slot per
55    long bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags)
77 helper. This helper returns a pointer to the value associated with
106 value in the hash slot for a specific CPU. Returns value associated with
148 struct value.
159     struct value {
168             __type(value, struct value);
181             struct value *value = bpf_map_lookup_elem(&packet_stats, &key);
183             if (value) {
184                     __sync_fetch_and_add(&value->packets, 1);
185                     __sync_fetch_and_add(&value->bytes, bytes);
187                     struct value newval = { 1, bytes };
204             struct value value;
212                     bpf_map_lookup_elem(map_fd, &next_key, &value);
214                     // Use key and value here