1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/bpf.h>
4 #include <bpf/bpf_helpers.h>
5
6 struct {
7 __uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
8 __type(key, struct bpf_cgroup_storage_key);
9 __type(value, __u64);
10 } cgroup_storage SEC(".maps");
11
12 SEC("cgroup_skb/egress")
13 int bpf_prog(struct __sk_buff *skb)
14 {
15 __u64 *counter;
16
17 counter = bpf_get_local_storage(&cgroup_storage, 0);
18 __sync_fetch_and_add(counter, 1);
19
20 /* Drop one out of every two packets */
21 return (*counter & 1);
22 }
23
24 char _license[] SEC("license") = "GPL";
25
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