Re: [PATCH bpf-next v2 6/9] bpf: iterators: install libbpf headers when building

API headers from libbpf should not be accessed directly from the
library's source directory. Instead, they should be exported with "make
install_headers". Let's make sure that bpf/preload/iterators/Makefile
installs the headers properly when building.

Signed-off-by: Quentin Monnet <redacted>
---
 kernel/bpf/preload/iterators/Makefile | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/bpf/preload/iterators/Makefile b/kernel/bpf/preload/iterators/Makefile
index 28fa8c1440f4..cf549dab3e20 100644
--- a/kernel/bpf/preload/iterators/Makefile
+++ b/kernel/bpf/preload/iterators/Makefile

@@ -6,9 +6,11 @@ LLVM_STRIP ?= llvm-strip
 DEFAULT_BPFTOOL := $(OUTPUT)/sbin/bpftool
 BPFTOOL ?= $(DEFAULT_BPFTOOL)
 LIBBPF_SRC := $(abspath ../../../../tools/lib/bpf)
-BPFOBJ := $(OUTPUT)/libbpf.a
-BPF_INCLUDE := $(OUTPUT)
-INCLUDES := -I$(OUTPUT) -I$(BPF_INCLUDE) -I$(abspath ../../../../tools/lib)        \
+LIBBPF_OUTPUT := $(abspath $(OUTPUT))/libbpf
+LIBBPF_DESTDIR := $(LIBBPF_OUTPUT)
+LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)/include
+BPFOBJ := $(LIBBPF_OUTPUT)/libbpf.a
+INCLUDES := -I$(OUTPUT) -I$(LIBBPF_INCLUDE)                                   \
        -I$(abspath ../../../../tools/include/uapi)
 CFLAGS := -g -Wall

@@ -44,13 +46,15 @@ $(OUTPUT)/iterators.bpf.o: iterators.bpf.c $(BPFOBJ) | $(OUTPUT)
                 -c $(filter %.c,$^) -o $@ &&                                 \
        $(LLVM_STRIP) -g $@

-$(OUTPUT):
+$(OUTPUT) $(LIBBPF_OUTPUT) $(LIBBPF_INCLUDE):
        $(call msg,MKDIR,$@)
-       $(Q)mkdir -p $(OUTPUT)
+       $(Q)mkdir -p $@

-$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)
+$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile)            \
+          | $(LIBBPF_OUTPUT) $(LIBBPF_INCLUDE)