Currently, some samples are using ioctl for enabling perf_event and
attaching BPF programs to this event. However, the bpf_program__attach
of libbpf(using bpf_link) is much more intuitive than the previous
method using ioctl.

bpf_program__attach_perf_event manages the enable of perf_event and
attach of BPF programs to it, so there's no neeed to do this
directly with ioctl.

In addition, bpf_link provides consistency in the use of API because it
allows disable (detach, destroy) for multiple events to be treated as
one bpf_link__destroy.

To refactor samples with using this libbpf API, the bpf_load in the
samples were removed and migrated to libbbpf. Because read_trace_pipe
is used in bpf_load, multiple samples cannot be migrated to libbpf,
this function was moved to trace_helpers.

Changes in v2:
 - check memory allocation is successful
 - clean up allocated memory on error

Changes in v3:
 - Improve pointer error check (IS_ERR())
 - change to calloc for easier destroy of bpf_link
 - remove perf_event fd list since bpf_link handles fd
 - use newer bpf_object__{open/load} API instead of bpf_prog_load
 - perf_event for _SC_NPROCESSORS_ONLN instead of _SC_NPROCESSORS_CONF
 - sample specific chagnes...

Changes in v4:
 - bpf_link *, bpf_object * set NULL on init & err for easier destroy
 - close bpf object with bpf_object__close()

Changes in v5:
 - on error, return error code with exit

Daniel T. Lee (2):
  samples: bpf: move read_trace_pipe to trace_helpers
  samples: bpf: refactor perf_event user program with libbpf bpf_link

 samples/bpf/Makefile                        |   8 +-
 samples/bpf/bpf_load.c                      |  20 ---
 samples/bpf/bpf_load.h                      |   1 -
 samples/bpf/sampleip_user.c                 |  98 +++++++++-----
 samples/bpf/trace_event_user.c              | 139 +++++++++++++-------
 samples/bpf/tracex1_user.c                  |   1 +
 samples/bpf/tracex5_user.c                  |   1 +
 tools/testing/selftests/bpf/trace_helpers.c |  23 ++++
 tools/testing/selftests/bpf/trace_helpers.h |   1 +
 9 files changed, 187 insertions(+), 105 deletions(-)

-- 
2.25.1