Re: [PATCH bpf-next v4 09/10] selftests: Remove tools/lib/bpf from include path

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Fri, Jan 17, 2020 at 5:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> From: Toke Høiland-Jørgensen <toke@redhat.com>
>
> To make sure no new files are introduced that doesn't include the bpf/
> prefix in its #include, remove tools/lib/bpf from the include path
> entirely.
>
> Instead, we introduce a new header files directory under the scratch tools/
> dir, and add a rule to run the 'install_headers' rule from libbpf to have a
> full set of consistent libbpf headers in $(OUTPUT)/tools/include/bpf, and
> then use $(OUTPUT)/tools/include as the include path for selftests.
>
> For consistency we also make sure we put all the scratch build files from
> other bpftool and libbpf into tools/build/, so everything stays within
> selftests/.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
>  tools/testing/selftests/bpf/.gitignore |    2 +
>  tools/testing/selftests/bpf/Makefile   |   49 +++++++++++++++++++++-----------
>  2 files changed, 33 insertions(+), 18 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index 1d14e3ab70be..8c9eac626996 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -39,4 +39,4 @@ test_cpp
>  /no_alu32
>  /bpf_gcc
>  /tools
> -bpf_helper_defs.h

can you please also drop libbpf.pc and libbpf.so.* rules from .gitignore?

> +
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 858d4e3369ad..ac0292a82fdc 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -20,8 +20,8 @@ CLANG         ?= clang
>  LLC            ?= llc
>  LLVM_OBJCOPY   ?= llvm-objcopy
>  BPF_GCC                ?= $(shell command -v bpf-gcc;)
> -CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(CURDIR) -I$(APIDIR) -I$(LIBDIR)  \
> -         -I$(BPFDIR) -I$(GENDIR) -I$(TOOLSINCDIR)                      \
> +CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(CURDIR) -I$(APIDIR)              \

extra space here

> +         -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) -I$(TOOLSINCDIR)     \
>           -Dbpf_prog_load=bpf_prog_test_load                            \
>           -Dbpf_load_program=bpf_test_load_program
>  LDLIBS += -lcap -lelf -lz -lrt -lpthread
> @@ -97,11 +97,15 @@ OVERRIDE_TARGETS := 1
>  override define CLEAN
>         $(call msg,CLEAN)
>         $(RM) -r $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) $(EXTRA_CLEAN)
> -       $(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/ clean
>  endef
>
>  include ../lib.mk
>
> +SCRATCH_DIR := $(OUTPUT)/tools
> +BUILD_DIR := $(SCRATCH_DIR)/build
> +INCLUDE_DIR := $(SCRATCH_DIR)/include
> +INCLUDE_BPF := $(INCLUDE_DIR)/bpf
> +
>  # Define simple and short `make test_progs`, `make test_sysctl`, etc targets
>  # to build individual tests.
>  # NOTE: Semicolon at the end is critical to override lib.mk's default static
> @@ -120,7 +124,7 @@ $(OUTPUT)/urandom_read: urandom_read.c
>         $(call msg,BINARY,,$@)
>         $(CC) -o $@ $< -Wl,--build-id
>
> -$(OUTPUT)/test_stub.o: test_stub.c
> +$(OUTPUT)/test_stub.o: test_stub.c $(INCLUDE_BPF)
>         $(call msg,CC,,$@)
>         $(CC) -c $(CFLAGS) -o $@ $<
>
> @@ -133,7 +137,7 @@ $(OUTPUT)/runqslower: force
>         $(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower     \
>                     OUTPUT=$(OUTPUT)/tools/ VMLINUX_BTF=$(VMLINUX_BTF)
>
> -BPFOBJ := $(OUTPUT)/libbpf.a
> +BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a
>
>  $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/test_stub.o $(BPFOBJ)
>
> @@ -159,17 +163,28 @@ force:
>  DEFAULT_BPFTOOL := $(OUTPUT)/tools/sbin/bpftool
>  BPFTOOL ?= $(DEFAULT_BPFTOOL)
>
> -$(DEFAULT_BPFTOOL): force
> -       $(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)                       \
> +$(BUILD_DIR)/libbpf $(BUILD_DIR)/bpftool $(INCLUDE_DIR):
> +       $(call msg,MKDIR,,$@)
> +       mkdir -p $@
> +
> +$(DEFAULT_BPFTOOL): force | $(BUILD_DIR)/bpftool
> +       $(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)         \

slash alignment


> +                   OUTPUT=$(BUILD_DIR)/bpftool/                        \
>                     prefix= DESTDIR=$(OUTPUT)/tools/ install
>
> -$(BPFOBJ): force
> -       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(OUTPUT)/
> +$(BPFOBJ): force | $(BUILD_DIR)/libbpf
> +       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) \
> +               OUTPUT=$(BUILD_DIR)/libbpf/
> +
> +$(INCLUDE_BPF): $(BPFOBJ) | $(INCLUDE_DIR)
> +       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) install_headers \
> +               OUTPUT=$(BUILD_DIR)/libbpf/ DESTDIR=$(SCRATCH_DIR) prefix=
> +
> +BPF_HELPERS := $(or $(wildcard $(INCLUDE_BPF)/bpf_*.h),$(INCLUDE_BPF))
> +ifneq ($(BPF_HELPERS),$(INCLUDE_BPF))
> +$(BPF_HELPERS): $(INCLUDE_BPF)
> +endif
>
> -BPF_HELPERS := $(OUTPUT)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)
> -$(OUTPUT)/bpf_helper_defs.h: $(BPFOBJ)
> -       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                            \
> -                   OUTPUT=$(OUTPUT)/ $(OUTPUT)/bpf_helper_defs.h
>

I really-really didn't like this alternating dependency on directory
or a set of file, depending on current state of those temporary
directories. Then also this ugly check to avoid circular dependency.
All that seemed wrong. So I played a bit with how to achieve the same
differently, and here's what I came up with, which I like a bit
better. What do you think?

$(BPFOBJ): $(wildcard $(BPFDIR)/*.c $(BPFDIR)/*.h $(BPFDIR)/Makefile)          \
           ../../../include/uapi/linux/bpf.h                                   \
           | $(INCLUDE_DIR) $(BUILD_DIR)/libbpf
        $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
                    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers

So, essentially, just make sure that we install local copies of
headers whenever libbpf.a needs to be re-built.
../../../include/uapi/linux/bpf.h ensures we don't miss uapi header
changes as well. Now anything that uses libbpf headers will need to
depend on $(BPFOBJ) and will automatically get up-to-date local copies
of headers.

This seems much simpler. Please give it a try, thanks!

>  # Get Clang's default includes on this system, as opposed to those seen by
>  # '-target bpf'. This fixes "missing" files on some architectures/distros,
> @@ -189,8 +204,8 @@ MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
>
>  CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
>  BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN)                  \
> -            -I$(OUTPUT) -I$(CURDIR) -I$(CURDIR)/include/uapi           \
> -            -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) -I$(abspath $(OUTPUT)/../usr/include)
> +            -I$(INCLUDE_DIR) -I$(CURDIR) -I$(CURDIR)/include/uapi      \
> +            -I$(APIDIR) -I$(abspath $(OUTPUT)/../usr/include)
>
>  CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
>                -Wno-compare-distinct-pointer-types
> @@ -392,7 +407,7 @@ $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
>         $(call msg,CXX,,$@)
>         $(CXX) $(CFLAGS) $^ $(LDLIBS) -o $@
>
> -EXTRA_CLEAN := $(TEST_CUSTOM_PROGS)                                    \
> +EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR)                     \
>         prog_tests/tests.h map_tests/tests.h verifier/tests.h           \
>         feature                                                         \
> -       $(addprefix $(OUTPUT)/,*.o *.skel.h no_alu32 bpf_gcc tools)
> +       $(addprefix $(OUTPUT)/,*.o *.skel.h no_alu32 bpf_gcc)
>