On Thu, Jul 22, 2021 at 05:27:47PM -0700, Stanislav Fomichev wrote:
> 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).
>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> ---
> kernel/bpf/local_storage.c | 12 +++++-
> tools/testing/selftests/bpf/netcnt_common.h | 38 +++++++++++++++----
> .../testing/selftests/bpf/progs/netcnt_prog.c | 29 +++++++-------
> tools/testing/selftests/bpf/test_netcnt.c | 25 +++++++-----
> 4 files changed, 73 insertions(+), 31 deletions(-)
>
> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> index 7ed2a14dc0de..a276da74c20a 100644
> --- a/kernel/bpf/local_storage.c
> +++ b/kernel/bpf/local_storage.c
> @@ -1,6 +1,7 @@
> //SPDX-License-Identifier: GPL-2.0
> #include <linux/bpf-cgroup.h>
> #include <linux/bpf.h>
> +#include <linux/bpf_local_storage.h>
> #include <linux/btf.h>
> #include <linux/bug.h>
> #include <linux/filter.h>
> @@ -284,8 +285,17 @@ static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
> static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
> {
> int numa_node = bpf_map_attr_numa_node(attr);
> + __u32 max_value_size = PCPU_MIN_UNIT_SIZE;
> struct bpf_cgroup_storage_map *map;
>
> + /* percpu is bound by PCPU_MIN_UNIT_SIZE, non-percu
> + * is the same as other local storages.
> + */
> + if (attr->map_type == BPF_MAP_TYPE_CGROUP_STORAGE)
> + max_value_size = BPF_LOCAL_STORAGE_MAX_VALUE_SIZE;
> +
> + BUILD_BUG_ON(PCPU_MIN_UNIT_SIZE > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE);
If PCPU_MIN_UNIT_SIZE did become larger, I assume it would be bounded by
BPF_LOCAL_STORAGE_MAX_VALUE_SIZE again?
Instead of BUILD_BUG_ON, how about a min_t here:
if (attr->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
max_value_size = min_t(__u32,
BPF_LOCAL_STORAGE_MAX_VALUE_SIZE,
PCPU_MIN_UNIT_SIZE);
