[PATCH v2 bpf-next 0/5] libbpf: error reporting changes for v1.0

[Andrii Nakryiko <andrii@kernel.org>]

Implement error reporting changes discussed in "Libbpf: the road to v1.0"
([0]) document.

Libbpf gets a new API, libbpf_set_strict_mode() which accepts a set of flags
that turn on a set of libbpf 1.0 changes, that might be potentially breaking.
It's possible to opt-in into all current and future 1.0 features by specifying
LIBBPF_STRICT_ALL flag.

When some of the 1.0 "features" are requested, libbpf APIs might behave
differently. In this patch set a first set of changes are implemented, all
related to the way libbpf returns errors. See individual patches for details.

Patch #1 adds a no-op libbpf_set_strict_mode() functionality to enable
updating selftests.

Patch #2 gets rid of all the bad code patterns that will break in libbpf 1.0
(exact -1 comparison for low-level APIs, direct IS_ERR() macro usage to check
pointer-returning APIs for error, etc). These changes make selftest work in
both legacy and 1.0 libbpf modes. Selftests also opt-in into 100% libbpf 1.0
mode to automatically gain all the subsequent changes, which will come in
follow up patches.

Patch #3 streamlines error reporting for low-level APIs wrapping bpf() syscall.

Patch #4 streamlines errors for all the rest APIs.

Patch #5 ensures that BPF skeletons propagate errors properly as well, as
currently on error some APIs will return NULL with no way of checking exact
error code.

  [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY

v1->v2:
  - move libbpf_set_strict_mode() implementation to patch #1, where it belongs
    (Alexei);
  - add acks, slight rewording of commit messages.

Andrii Nakryiko (5):
  libbpf: add libbpf_set_strict_mode() API to turn on libbpf 1.0
    behaviors
  selftests/bpf: turn on libbpf 1.0 mode and fix all IS_ERR checks
  libbpf: streamline error reporting for low-level APIs
  libbpf: streamline error reporting for high-level APIs
  bpftool: set errno on skeleton failures and propagate errors

 tools/bpf/bpftool/gen.c                       |  27 +-
 tools/lib/bpf/Makefile                        |   1 +
 tools/lib/bpf/bpf.c                           | 168 ++++--
 tools/lib/bpf/bpf_prog_linfo.c                |  18 +-
 tools/lib/bpf/btf.c                           | 302 +++++-----
 tools/lib/bpf/btf_dump.c                      |  14 +-
 tools/lib/bpf/libbpf.c                        | 519 ++++++++++--------
 tools/lib/bpf/libbpf.h                        |   1 +
 tools/lib/bpf/libbpf.map                      |   5 +
 tools/lib/bpf/libbpf_errno.c                  |   7 +-
 tools/lib/bpf/libbpf_internal.h               |  53 ++
 tools/lib/bpf/libbpf_legacy.h                 |  59 ++
 tools/lib/bpf/linker.c                        |  22 +-
 tools/lib/bpf/netlink.c                       |  81 +--
 tools/lib/bpf/ringbuf.c                       |  26 +-
 tools/testing/selftests/bpf/bench.c           |   1 +
 .../selftests/bpf/benchs/bench_rename.c       |   2 +-
 .../selftests/bpf/benchs/bench_ringbufs.c     |   6 +-
 .../selftests/bpf/benchs/bench_trigger.c      |   2 +-
 .../selftests/bpf/prog_tests/attach_probe.c   |  12 +-
 .../selftests/bpf/prog_tests/bpf_iter.c       |  31 +-
 .../selftests/bpf/prog_tests/bpf_tcp_ca.c     |   8 +-
 tools/testing/selftests/bpf/prog_tests/btf.c  |  93 ++--
 .../selftests/bpf/prog_tests/btf_dump.c       |   8 +-
 .../selftests/bpf/prog_tests/btf_write.c      |   4 +-
 .../bpf/prog_tests/cg_storage_multi.c         |  84 +--
 .../bpf/prog_tests/cgroup_attach_multi.c      |   2 +-
 .../selftests/bpf/prog_tests/cgroup_link.c    |  14 +-
 .../bpf/prog_tests/cgroup_skb_sk_lookup.c     |   2 +-
 .../selftests/bpf/prog_tests/check_mtu.c      |   2 +-
 .../selftests/bpf/prog_tests/core_reloc.c     |  15 +-
 .../selftests/bpf/prog_tests/fexit_bpf2bpf.c  |  25 +-
 .../selftests/bpf/prog_tests/flow_dissector.c |   2 +-
 .../bpf/prog_tests/flow_dissector_reattach.c  |  10 +-
 .../bpf/prog_tests/get_stack_raw_tp.c         |  10 +-
 .../prog_tests/get_stackid_cannot_attach.c    |   9 +-
 .../selftests/bpf/prog_tests/hashmap.c        |   9 +-
 .../selftests/bpf/prog_tests/kfree_skb.c      |  19 +-
 .../selftests/bpf/prog_tests/ksyms_btf.c      |   3 +-
 .../selftests/bpf/prog_tests/link_pinning.c   |   7 +-
 .../selftests/bpf/prog_tests/obj_name.c       |   8 +-
 .../selftests/bpf/prog_tests/perf_branches.c  |   4 +-
 .../selftests/bpf/prog_tests/perf_buffer.c    |   2 +-
 .../bpf/prog_tests/perf_event_stackmap.c      |   3 +-
 .../selftests/bpf/prog_tests/probe_user.c     |   7 +-
 .../selftests/bpf/prog_tests/prog_run_xattr.c |   4 +-
 .../bpf/prog_tests/raw_tp_test_run.c          |   4 +-
 .../selftests/bpf/prog_tests/rdonly_maps.c    |   7 +-
 .../bpf/prog_tests/reference_tracking.c       |   2 +-
 .../selftests/bpf/prog_tests/resolve_btfids.c |   2 +-
 .../selftests/bpf/prog_tests/ringbuf_multi.c  |   2 +-
 .../bpf/prog_tests/select_reuseport.c         |  53 +-
 .../selftests/bpf/prog_tests/send_signal.c    |   3 +-
 .../selftests/bpf/prog_tests/sk_lookup.c      |   2 +-
 .../selftests/bpf/prog_tests/sock_fields.c    |  14 +-
 .../selftests/bpf/prog_tests/sockmap_basic.c  |   8 +-
 .../selftests/bpf/prog_tests/sockmap_ktls.c   |   2 +-
 .../selftests/bpf/prog_tests/sockmap_listen.c |  10 +-
 .../bpf/prog_tests/stacktrace_build_id_nmi.c  |   3 +-
 .../selftests/bpf/prog_tests/stacktrace_map.c |   2 +-
 .../bpf/prog_tests/stacktrace_map_raw_tp.c    |   5 +-
 .../bpf/prog_tests/tcp_hdr_options.c          |  15 +-
 .../selftests/bpf/prog_tests/test_overhead.c  |  12 +-
 .../bpf/prog_tests/trampoline_count.c         |  14 +-
 .../selftests/bpf/prog_tests/udp_limit.c      |   7 +-
 .../selftests/bpf/prog_tests/xdp_bpf2bpf.c    |   2 +-
 .../selftests/bpf/prog_tests/xdp_link.c       |   8 +-
 tools/testing/selftests/bpf/test_maps.c       | 168 +++---
 tools/testing/selftests/bpf/test_progs.c      |   3 +
 tools/testing/selftests/bpf/test_progs.h      |   9 +-
 .../selftests/bpf/test_tcpnotify_user.c       |   7 +-
 71 files changed, 1123 insertions(+), 952 deletions(-)
 create mode 100644 tools/lib/bpf/libbpf_legacy.h

-- 
2.30.2