[PATCH bpf-next 0/2] bpftool: Consume ring buffer maps with event_pipe

[Tianyi Chen <hi@tychen.cc>]

This series extends map event_pipe to BPF ring buffer maps through
libbpf's ring buffer manager. Records contain a size and raw bytes in
plain or JSON output. CPU/index selectors remain perf-array specific.
The documentation explains the shared, destructive consumer position.

The existing perf event array path is retained. Signal handlers only set
a stop flag; messages and JSON closure happen in the main path. Poll
and output errors return failure instead of silently ending a stream.

Related request:
https://github.com/libbpf/bpftool/issues/54

The series is based on bpf-next and is independent of the flags and
batch-dump series sent alongside it.

Validation:
- Full bpftool and focused BPF selftests builds with LLVM 20, plus
  bpftool-map man page generation and Bash completion syntax checks.
- All 12 bpftool_ringbuf subtests passed in an x86-64 KVM guest running
  Linux 7.3.0-rc1, against a bpftool built with only this series.
- The perf event array regression also passed against unmodified bpftool.
- Injecting EIO into epoll_wait returned failure with an errno diagnostic
  on stderr and a complete empty JSON array on stdout.

Only focused tests were run; this does not claim a full BPF selftest
suite run. Strict checkpatch has no errors or checks. Remaining warnings
are the userspace volatile sig_atomic_t signal flag, readable multiline
expected-output strings, and files covered by existing MAINTAINERS
patterns.


Integration check: these three independent series also applied and built
together with my previously posted recursive map-dump v2 series. The
combined 64 subtests passed with no skips or failures in the same guest.

Tianyi Chen (2):
  bpftool: Read ring buffer maps with event_pipe
  selftests/bpf: Cover bpftool ring buffer event_pipe

 .../bpf/bpftool/Documentation/bpftool-map.rst |  15 +-
 tools/bpf/bpftool/bash-completion/bpftool     |   4 +-
 tools/bpf/bpftool/map_perf_ring.c             |  87 +++-
 .../bpf/prog_tests/bpftool_ringbuf.c          | 381 ++++++++++++++++++
 .../selftests/bpf/progs/bpftool_ringbuf.c     |  47 +++
 5 files changed, 510 insertions(+), 24 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpftool_ringbuf.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpftool_ringbuf.c

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2.55.0