On Thu, Jul 29, 2021 at 9:20 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote: > > As part of the effort to move towards a v1.0 for libbpf [0], this set > improves some confusing function names related to BTF loading from and to > the kernel: > > - btf__load() becomes btf__load_into_kernel(). > - btf__get_from_id becomes btf__load_from_kernel_by_id(). > - A new version btf__load_from_kernel_by_id_split() extends the former to > add support for split BTF. > > The old functions are marked for deprecation for the next minor version > (0.6) of libbpf. > > The last patch is a trivial change to bpftool to add support for dumping > split BTF objects by referencing them by their id (and not only by their > BTF path). > > [0] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis > > v3: > - Use libbpf_err_ptr() in btf__load_from_kernel_by_id(), ERR_PTR() in > bpftool's get_map_kv_btf(). > - Move the definition of btf__load_from_kernel_by_id() closer to the > btf__parse() group in btf.h (move the legacy function with it). > - Fix a bug on the return value in libbpf_find_prog_btf_id(), as a new > patch. > - Move the btf__free() fixes to their own patch. > - Add "Fixes:" tags to relevant patches. > - Re-introduce deprecation (removed in v2) for the legacy functions, as a > new macro LIBBPF_DEPRECATED_SINCE(major, minor, message). > > v2: > - Remove deprecation marking of legacy functions (patch 4/6 from v1). > - Make btf__load_from_kernel_by_id{,_split}() return the btf struct, adjust > surrounding code and call btf__free() when missing. > - Add new functions to v0.5.0 API (and not v0.6.0). > > Quentin Monnet (8): > libbpf: return non-null error on failures in libbpf_find_prog_btf_id() > libbpf: rename btf__load() as btf__load_into_kernel() > libbpf: rename btf__get_from_id() as btf__load_from_kernel_by_id() > tools: free BTF objects at various locations > tools: replace btf__get_from_id() with btf__load_from_kernel_by_id() > libbpf: prepare deprecation of btf__get_from_id(), btf__load() > libbpf: add split BTF support for btf__load_from_kernel_by_id() > tools: bpftool: support dumping split BTF by id > > tools/bpf/bpftool/btf.c | 8 ++--- > tools/bpf/bpftool/btf_dumper.c | 6 ++-- > tools/bpf/bpftool/map.c | 14 ++++----- > tools/bpf/bpftool/prog.c | 29 +++++++++++------ > tools/lib/bpf/Makefile | 3 ++ > tools/lib/bpf/btf.c | 33 ++++++++++++++------ > tools/lib/bpf/btf.h | 7 ++++- > tools/lib/bpf/libbpf.c | 11 ++++--- > tools/lib/bpf/libbpf.map | 3 ++ > tools/lib/bpf/libbpf_common.h | 19 +++++++++++ > tools/perf/util/bpf-event.c | 11 ++++--- > tools/perf/util/bpf_counter.c | 12 +++++-- > tools/testing/selftests/bpf/prog_tests/btf.c | 4 ++- > 13 files changed, 113 insertions(+), 47 deletions(-) > > -- > 2.30.2 > I dropped patch #7 with deprecations and LIBBPF_DEPRECATED_SINCE and applied to bpf-next. Current LIBBPF_DEPRECATED_SINCE approach doesn't work (and you should have caught this when you built selftests/bpf, what happened there?). bpftool build generates warnings like this: In file included from /data/users/andriin/linux/tools/lib/bpf/libbpf.h:20, from xlated_dumper.c:10: /data/users/andriin/linux/tools/lib/bpf/libbpf_common.h:22:23: warning: "LIBBPF_MAJOR_VERSION" is not defined, evaluates to 0 [-Wundef] __LIBBPF_GET_VERSION(LIBBPF_MAJOR_VERSION, LIBBPF_MINOR_VERSION) ^~~~~~~~~~~~~~~~~~~~ And it makes total sense. LIBBPF_DEPRECATED_SINCE() assumes LIBBPF_MAJOR_VERSION/LIBBPF_MINOR_VERSION is defined at compilation time of the *application that is using libbpf*, not just libbpf's compilation time. And that's clearly a bogus assumption which we can't and shouldn't make. The right approach will be to define LIBBPF_MAJOR_VERSION/LIBBPF_MINOR_VERSION in some sort of auto-generated header, included from libbpf_common.h and installed as part of libbpf package. Anyways, I've removed all the LIBBPF_DEPRECATED_SINCE stuff and applied all the rest, as it looks good and is a useful addition. We should work some more on deprecation helpers, though.
