bpf: Increase supported cgroup storage value size

Current max cgroup storage value size is 4k (PAGE_SIZE). The other local
storages accept up to 64k (BPF_LOCAL_STORAGE_MAX_VALUE_SIZE). Let's align
max cgroup value size with the other storages.

For percpu, the max is 32k (PCPU_MIN_UNIT_SIZE) because percpu
allocator is not happy about larger values.

netcnt test is extended to exercise those maximum values
(non-percpu max size is close to, but not real max).

v4:
* remove inner union (Andrii Nakryiko)
* keep net_cnt on the stack (Andrii Nakryiko)

v3:
* refine SIZEOF_BPF_LOCAL_STORAGE_ELEM comment (Yonghong Song)
* anonymous struct in percpu_net_cnt & net_cnt (Yonghong Song)
* reorder free (Yonghong Song)

v2:
* cap max_value_size instead of BUILD_BUG_ON (Martin KaFai Lau)

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210727222335.4029096-1-sdf@google.com

1 files changed, 4 insertions, 4 deletions

diff --git a/tools/testing/selftests/bpf/progs/netcnt_prog.c b/tools/testing/selftests/bpf/progs/netcnt_prog.c
index d071adf178bd..43649bce4c54 100644
--- a/tools/testing/selftests/bpf/progs/netcnt_prog.c
+++ b/tools/testing/selftests/bpf/progs/netcnt_prog.c
@@ -13,21 +13,21 @@
 struct {
 	__uint(type, BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
 	__type(key, struct bpf_cgroup_storage_key);
-	__type(value, struct percpu_net_cnt);
+	__type(value, union percpu_net_cnt);
 } percpu_netcnt SEC(".maps");
 
 struct {
 	__uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
 	__type(key, struct bpf_cgroup_storage_key);
-	__type(value, struct net_cnt);
+	__type(value, union net_cnt);
 } netcnt SEC(".maps");
 
 SEC("cgroup/skb")
 int bpf_nextcnt(struct __sk_buff *skb)
 {
-	struct percpu_net_cnt *percpu_cnt;
+	union percpu_net_cnt *percpu_cnt;
 	char fmt[] = "%d %llu %llu\n";
-	struct net_cnt *cnt;
+	union net_cnt *cnt;
 	__u64 ts, dt;
 	int ret;