[PATCH bpf-next v4 0/4] bpf: add BPF_CGROUP_INET_SOCK_RELEASE hook

[Stanislav Fomichev <sdf@google.com>]

Sometimes it's handy to know when the socket gets freed.
In particular, we'd like to try to use a smarter allocation
of ports for bpf_bind and explore the possibility of
limiting the number of SOCK_DGRAM sockets the process can have.

There is already existing BPF_CGROUP_INET_SOCK_CREATE hook
that triggers upon socket creation; let's add new hook
(BPF_CGROUP_INET_SOCK_RELEASE) that triggers on socket release.

v4:
* initialize global BPF vars (Andrii Nakryiko)
* simplify error handling (Andrii Nakryiko)

v3:
* s/CHECK_FAIL/CHECK/ (Andrii Nakryiko)
* s/bpf_prog_attach/bpf_program__attach_cgroup/ (Andrii Nakryiko)
* fix &in_use in BPF program (Andrii Nakryiko)

v2:
* fix compile issue with CONFIG_CGROUP_BPF=n (kernel test robot)

Stanislav Fomichev (4):
  bpf: add BPF_CGROUP_INET_SOCK_RELEASE hook
  libbpf: add support for BPF_CGROUP_INET_SOCK_RELEASE
  bpftool: add support for BPF_CGROUP_INET_SOCK_RELEASE
  selftests/bpf: test BPF_CGROUP_INET_SOCK_RELEASE

 include/linux/bpf-cgroup.h                    |  4 +
 include/uapi/linux/bpf.h                      |  1 +
 kernel/bpf/syscall.c                          |  3 +
 net/core/filter.c                             |  1 +
 net/ipv4/af_inet.c                            |  3 +
 tools/bpf/bpftool/common.c                    |  1 +
 tools/include/uapi/linux/bpf.h                |  1 +
 tools/lib/bpf/libbpf.c                        |  4 +
 .../selftests/bpf/prog_tests/udp_limit.c      | 75 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/udp_limit.c | 42 +++++++++++
 10 files changed, 135 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/udp_limit.c
 create mode 100644 tools/testing/selftests/bpf/progs/udp_limit.c

-- 
2.27.0.212.ge8ba1cc988-goog