On 9/8/21 8:55 AM, Andrii Nakryiko wrote:
From: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare
the deprecation of two API functions. This macro marks functions as deprecated
when libbpf's version reaches the values passed as an argument.
As part of this change libbpf_version.h header is added with recorded major
(LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros.
They are now part of libbpf public API and can be relied upon by user code.
libbpf_version.h is installed system-wide along other libbpf public headers.
Due to this new build-time auto-generated header, in-kernel applications
relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to
include libbpf's output directory as part of a list of include search paths.
Better fix would be to use libbpf's make_install target to install public API
headers, but that clean up is left out as a future improvement. The build
changes were tested by building kernel (with KBUILD_OUTPUT and O= specified
explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No
problems were detected.
Note that because of the constraints of the C preprocessor we have to write
a few lines of macro magic for each version used to prepare deprecation (0.6
for now).
Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of
btf__get_from_id() and btf__load(), which are replaced by
btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively,
starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/278
Co-developed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
v1->v2:
- fix bpf_preload build by adding dependency for iterators/iterators.o on
libbpf.a generation (caught by BPF CI);
[...]
@@ -136,7 +140,7 @@ all: fixdep
all_cmd: $(CMD_TARGETS) check
-$(BPF_IN_SHARED): force $(BPF_HELPER_DEFS)
+$(BPF_IN_SHARED): force $(BPF_GENERATED)
@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \
(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
@@ -154,13 +158,19 @@ $(BPF_IN_SHARED): force $(BPF_HELPER_DEFS)
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true
$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(SHARED_OBJDIR) CFLAGS="$(CFLAGS) $(SHLIB_FLAGS)"
-$(BPF_IN_STATIC): force $(BPF_HELPER_DEFS)
+$(BPF_IN_STATIC): force $(BPF_GENERATED)
$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(STATIC_OBJDIR)
$(BPF_HELPER_DEFS): $(srctree)/tools/include/uapi/linux/bpf.h
$(QUIET_GEN)$(srctree)/scripts/bpf_doc.py --header \
--file $(srctree)/tools/include/uapi/linux/bpf.h > $(BPF_HELPER_DEFS)
+$(VERSION_HDR): force
+ $(QUIET_GEN)echo "/* This file was auto-generated. */" > $@
+ @echo "" >> $@
+ @echo "#define LIBBPF_MAJOR_VERSION $(LIBBPF_MAJOR_VERSION)" >> $@
+ @echo "#define LIBBPF_MINOR_VERSION $(LIBBPF_MINOR_VERSION)" >> $@
+
Looks like CI caught a different issue this time with v2 where it cannot find libbpf_version.h:
[...]
CC bench_count.o
GEN /home/runner/work/bpf/bpf/tools/testing/selftests/bpf/bpf-helpers.rst
In file included from /home/runner/work/bpf/bpf/tools/lib/bpf/bpf.h:31,
from /home/runner/work/bpf/bpf/tools/testing/selftests/bpf/bench.h:8,
from benchs/bench_count.c:3:
/home/runner/work/bpf/bpf/tools/lib/bpf/libbpf_common.h:13:10: fatal error: libbpf_version.h: No such file or directory
13 | #include "libbpf_version.h"
| ^~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:517: /home/runner/work/bpf/bpf/tools/testing/selftests/bpf/bench_count.o] Error 1
make: *** Waiting for unfinished jobs....
GEN /home/runner/work/bpf/bpf/tools/testing/selftests/bpf/bpf-syscall.rst
In file included from /home/runner/work/bpf/bpf/tools/lib/bpf/bpf.h:31,
from bench.h:8,
from bench.c:13:
/home/runner/work/bpf/bpf/tools/lib/bpf/libbpf_common.h:13:10: fatal error: libbpf_version.h: No such file or directory
13 | #include "libbpf_version.h"
| ^~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:162: /home/runner/work/bpf/bpf/tools/testing/selftests/bpf/bench.o] Error 1
Thanks,
Daniel
