bpf: extend cgroup bpf core to allow multiple cgroup storage types

In order to introduce per-cpu cgroup storage, let's generalize
bpf cgroup core to support multiple cgroup storage types.
Potentially, per-node cgroup storage can be added later.

This commit is mostly a formal change that replaces
cgroup_storage pointer with a array of cgroup_storage pointers.
It doesn't actually introduce a new storage type,
it will be done later.

Each bpf program is now able to have one cgroup storage of each type.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1991466b8327..9070b2ace6aa 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -194,16 +194,18 @@ const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {
         .ret_type       = RET_INTEGER,
 };
 
-DECLARE_PER_CPU(void*, bpf_cgroup_storage);
+#ifdef CONFIG_CGROUP_BPF
+DECLARE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
 {
-        /* map and flags arguments are not used now,
-         * but provide an ability to extend the API
-         * for other types of local storages.
-         * verifier checks that their values are correct.
+        /* flags argument is not used now,
+         * but provides an ability to extend the API.
+         * verifier checks that its value is correct.
          */
-        return (unsigned long) this_cpu_read(bpf_cgroup_storage);
+        enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
+
+        return (unsigned long) this_cpu_read(bpf_cgroup_storage[stype]);
 }
 
 const struct bpf_func_proto bpf_get_local_storage_proto = {
@@ -214,3 +216,4 @@ const struct bpf_func_proto bpf_get_local_storage_proto = {
         .arg2_type      = ARG_ANYTHING,
 };
 #endif
+#endif