kbuild: unexport abs_srctree and abs_objtree

Commit 25b146c5b8 ("kbuild: allow Kbuild to start from any directory")
exported abs_srctree and abs_objtree to avoid recomputation after the
sub-make. However, this approach turned out to be fragile.

Commit 5fa94ceb79 ("kbuild: set correct abs_srctree and abs_objtree
for package builds") moved them above "ifneq ($(sub_make_done),1)",
eliminating the need for exporting them.

These are only needed in the top Makefile. If an absolute path is
required in sub-directories, you can use $(abspath ) or $(realpath )
as needed.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Makefile

@@ -39,8 +39,8 @@ __all:
 # prepare rule.
 
 this-makefile := $(lastword $(MAKEFILE_LIST))
-export abs_srctree := $(realpath $(dir $(this-makefile)))
-export abs_objtree := $(CURDIR)
+abs_srctree := $(realpath $(dir $(this-makefile)))
+abs_objtree := $(CURDIR)
 
 ifneq ($(sub_make_done),1)
 

rust/Makefile

@@ -100,7 +100,7 @@ rustdoc: rustdoc-core rustdoc-macros rustdoc-compiler_builtins \
 		-e 's:rust-logo-[0-9a-f]+\.svg:logo.svg:g' \
 		-e 's:favicon-[0-9a-f]+\.svg:logo.svg:g' \
 		-e 's:<link rel="alternate icon" type="image/png" href="[/.]+/static\.files/favicon-(16x16|32x32)-[0-9a-f]+\.png">::g' \
-		-e 's:<a href="srctree/([^"]+)">:<a href="$(abs_srctree)/\1">:g'
+		-e 's:<a href="srctree/([^"]+)">:<a href="$(realpath $(srctree))/\1">:g'
 	$(Q)for f in $(rustdoc_output)/static.files/rustdoc-*.css; do \
 		echo ".logo-container > img { object-fit: contain; }" >> $$f; done
 
@@ -413,7 +413,7 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 rust-analyzer:
 	$(Q)$(srctree)/scripts/generate_rust_analyzer.py \
 		--cfgs='core=$(core-cfgs)' --cfgs='alloc=$(alloc-cfgs)' \
-		$(abs_srctree) $(abs_objtree) \
+		$(realpath $(srctree)) $(realpath $(objtree)) \
 		$(RUST_LIB_SRC) $(KBUILD_EXTMOD) > \
 		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/rust-project.json
 

scripts/Makefile.package

@@ -135,7 +135,7 @@ snap-pkg:
 	mkdir $(objtree)/snap
 	$(MAKE) clean
 	sed "s@KERNELRELEASE@$(KERNELRELEASE)@; \
-		s@SRCTREE@$(abs_srctree)@" \
+		s@SRCTREE@$(realpath $(srctree))@" \
 		$(srctree)/scripts/package/snapcraft.template > \
 		$(objtree)/snap/snapcraft.yaml
 	cd $(objtree)/snap && \

tools/lib/bpf/Makefile

@@ -2,7 +2,7 @@
 # Most of this file is copied from tools/lib/traceevent/Makefile
 
 RM ?= rm
-srctree = $(abs_srctree)
+srctree := $(realpath $(srctree))
 
 VERSION_SCRIPT := libbpf.map
 LIBBPF_VERSION := $(shell \