On Tue, Jul 27, 2021 at 3:23 PM Stanislav Fomichev [off-list ref] 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).

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)

Cc: Martin KaFai Lau <redacted>
Cc: Yonghong Song <redacted>
Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Stanislav Fomichev <redacted>
---

Added Martin's ack and applied to bpf-next. Please carry over received
Acks between revisions.

It's also a good practice to separate selftest from the kernel (or
libbpf) changes, unless kernel change doesn't immediately break
selftest. Please consider doing that for the future.

I also just noticed that test_netcnt isn't part of test_progs. It
would be great to migrate it under the common test_progs
infrastructure. We've been steadily moving towards that, but there are
still a bunch of tests that are not run in CI.

 kernel/bpf/local_storage.c                    | 11 +++++-
 tools/testing/selftests/bpf/netcnt_common.h   | 38 ++++++++++++++-----
 .../testing/selftests/bpf/progs/netcnt_prog.c |  8 ++--
 tools/testing/selftests/bpf/test_netcnt.c     |  4 +-
 4 files changed, 45 insertions(+), 16 deletions(-)

[...]