kbuild: re-implement Makefile.headersinst without recursion

Since commit fcc8487d ("uapi: export all headers under uapi
directories"), the headers in uapi directories are all exported by
default although exceptional cases are still allowed by the syntax
'no-export-headers'.

The traditional directory descending has been kept (in a somewhat
hacky way), but it is actually unneeded.

Get rid of it to simplify the code.

Also, handle files one by one instead of the previous per-directory
processing. This will emit much more log, but I like it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1194,13 +1194,13 @@ PHONY += headers
 headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
 	$(if $(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/Kbuild),, \
 	  $(error Headers not exportable for the $(SRCARCH) architecture))
-	$(Q)$(MAKE) $(hdr-inst)=include/uapi dst=include
-	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi dst=include
+	$(Q)$(MAKE) $(hdr-inst)=include/uapi
+	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
 
 PHONY += headers_check
 headers_check: headers
-	$(Q)$(MAKE) $(hdr-inst)=include/uapi dst=include HDRCHECK=1
-	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi dst=include HDRCHECK=1
+	$(Q)$(MAKE) $(hdr-inst)=include/uapi HDRCHECK=1
+	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi HDRCHECK=1
 
 ifdef CONFIG_HEADERS_INSTALL
 prepare: headers

include/uapi/linux/Kbuild → include/uapi/Kbuild

 # SPDX-License-Identifier: GPL-2.0
 ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/a.out.h),)
-no-export-headers += a.out.h
+no-export-headers += linux/a.out.h
 endif
 
 ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/kvm.h),)
-no-export-headers += kvm.h
+no-export-headers += linux/kvm.h
 endif
 
 ifeq ($(wildcard $(srctree)/arch/$(SRCARCH)/include/uapi/asm/kvm_para.h),)
 ifeq ($(wildcard $(objtree)/arch/$(SRCARCH)/include/generated/uapi/asm/kvm_para.h),)
-no-export-headers += kvm_para.h
+no-export-headers += linux/kvm_para.h
 endif
 endif

scripts/Makefile.headersinst

@@ -14,109 +14,87 @@ __headers:
 
 include scripts/Kbuild.include
 
-srcdir        := $(srctree)/$(obj)
+src := $(srctree)/$(obj)
+gen := $(objtree)/$(subst include/,include/generated/,$(obj))
+dst := usr/include
 
-# When make is run under a fakechroot environment, the function
-# $(wildcard $(srcdir)/*/.) doesn't only return directories, but also regular
-# files. So, we are using a combination of sort/dir/wildcard which works
-# with fakechroot.
-subdirs       := $(patsubst $(srcdir)/%/,%,\
-		 $(filter-out $(srcdir)/,\
-		 $(sort $(dir $(wildcard $(srcdir)/*/)))))
+-include $(src)/Kbuild
 
-# Recursion
-__headers: $(subdirs)
+src-subdirs := $(patsubst $(src)/%/,%,$(wildcard $(src)/*/))
+gen-subdirs := $(patsubst $(gen)/%/,%,$(wildcard $(gen)/*/))
+all-subdirs := $(sort $(src-subdirs) $(gen-subdirs))
 
-PHONY += $(subdirs)
-$(subdirs):
-	$(Q)$(MAKE) $(hdr-inst)=$(obj)/$@ dst=$(dst)/$@
+src-headers := $(if $(src-subdirs), $(shell cd $(src) && find $(src-subdirs) -name '*.h'))
+src-headers := $(filter-out $(no-export-headers), $(src-headers))
+gen-headers := $(if $(gen-subdirs), $(shell cd $(gen) && find $(gen-subdirs) -name '*.h'))
+gen-headers := $(filter-out $(no-export-headers), $(gen-headers))
 
-# Skip header install/check for include/uapi and arch/$(SRCARCH)/include/uapi.
-# We have only sub-directories there.
-skip-inst := $(if $(filter %/uapi,$(obj)),1)
+# If the same header is exported from source and generated directories,
+# the former takes precedence, but this should be warned.
+duplicated := $(filter $(gen-headers), $(src-headers))
+$(if $(duplicated), $(warning duplicated header export: $(duplicated)))
 
-ifeq ($(skip-inst),)
+gen-headers := $(filter-out $(duplicated), $(gen-headers))
 
-# Kbuild file is optional
-kbuild-file := $(srctree)/$(obj)/Kbuild
--include $(kbuild-file)
+# Add dst path prefix
+all-subdirs := $(addprefix $(dst)/, $(all-subdirs))
+src-headers := $(addprefix $(dst)/, $(src-headers))
+gen-headers := $(addprefix $(dst)/, $(gen-headers))
+all-headers := $(src-headers) $(gen-headers)
 
-installdir    := usr/$(dst)
-gendir        := $(objtree)/$(subst include/,include/generated/,$(obj))
-header-files  := $(notdir $(wildcard $(srcdir)/*.h))
-header-files  := $(filter-out $(no-export-headers), $(header-files))
-genhdr-files  := $(notdir $(wildcard $(gendir)/*.h))
-genhdr-files  := $(filter-out $(header-files), $(genhdr-files))
+# Work out what needs to be removed
+old-subdirs := $(wildcard $(all-subdirs))
+old-headers := $(if $(old-subdirs),$(shell find $(old-subdirs) -name '*.h'))
+unwanted    := $(filter-out $(all-headers), $(old-headers))
 
-# files used to track state of install/check
-install-file  := $(installdir)/.install
-check-file    := $(installdir)/.check
+# Create directories
+existing-dirs := $(sort $(dir $(old-headers)))
+wanted-dirs   := $(sort $(dir $(all-headers)))
+new-dirs      := $(filter-out $(existing-dirs), $(wanted-dirs))
+$(if $(new-dirs), $(shell mkdir -p $(new-dirs)))
 
-# all headers files for this dir
-all-files     := $(header-files) $(genhdr-files)
-output-files  := $(addprefix $(installdir)/, $(all-files))
+# Rules
 
-# Work out what needs to be removed
-oldheaders    := $(patsubst $(installdir)/%,%,$(wildcard $(installdir)/*.h))
-unwanted      := $(filter-out $(all-files),$(oldheaders))
+ifndef HDRCHECK
 
-# Prefix unwanted with full paths to objtree
-unwanted-file := $(addprefix $(installdir)/, $(unwanted))
+quiet_cmd_install = HDRINST $@
+      cmd_install = $(CONFIG_SHELL) $(srctree)/scripts/headers_install.sh $(@D) $(<D) $(@F)
 
-printdir = $(patsubst %/,%,$(dir $@))
+$(src-headers): $(dst)/%.h: $(src)/%.h $(srctree)/scripts/headers_install.sh FORCE
+	$(call if_changed,install)
 
-quiet_cmd_install = INSTALL $(printdir) ($(words $(all-files))\
-                            file$(if $(word 2, $(all-files)),s))
-      cmd_install = \
-        $(CONFIG_SHELL) $< $(installdir) $(srcdir) $(header-files); \
-        $(CONFIG_SHELL) $< $(installdir) $(gendir) $(genhdr-files); \
-        touch $@
+$(gen-headers): $(dst)/%.h: $(gen)/%.h $(srctree)/scripts/headers_install.sh FORCE
+	$(call if_changed,install)
 
 quiet_cmd_remove = REMOVE  $(unwanted)
-      cmd_remove = rm -f $(unwanted-file)
-
-quiet_cmd_check = CHECK   $(printdir) ($(words $(all-files)) files)
-# Headers list can be pretty long, xargs helps to avoid
-# the "Argument list too long" error.
-      cmd_check = for f in $(all-files); do                          \
-                  echo "$(installdir)/$${f}"; done                      \
-                  | xargs                                            \
-                  $(PERL) $< usr/include $(SRCARCH); \
-	          touch $@
+      cmd_remove = rm -f $(unwanted)
 
-ifndef HDRCHECK
-# Rules for installing headers
-__headers: $(install-file)
+__headers: $(all-headers)
+ifneq ($(unwanted),)
+	$(call cmd,remove)
+endif
 	@:
 
-targets += $(install-file)
-$(install-file): scripts/headers_install.sh \
-		 $(addprefix $(srcdir)/,$(header-files)) \
-		 $(addprefix $(gendir)/,$(genhdr-files)) FORCE
-	$(if $(unwanted),$(call cmd,remove),)
-	$(if $(wildcard $(dir $@)),,$(shell mkdir -p $(dir $@)))
-	$(call if_changed,install)
+existing-headers := $(filter $(old-headers), $(all-headers))
+
+-include $(foreach f,$(existing-headers),$(dir $(f)).$(notdir $(f)).cmd)
 
 else
-__headers: $(check-file)
-	@:
 
-targets += $(check-file)
-$(check-file): scripts/headers_check.pl $(output-files) FORCE
-	$(call if_changed,check)
+quiet_cmd_check = HDRCHK  $<
+      cmd_check = $(PERL) $(srctree)/scripts/headers_check.pl $(dst) $(SRCARCH) $<; touch $@
 
-endif
+check-files := $(addsuffix .chk, $(all-headers))
 
-cmd_files := $(wildcard \
-             $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
+$(check-files): $(dst)/%.chk : $(dst)/% $(srctree)/scripts/headers_check.pl
+	$(call cmd,check)
 
-ifneq ($(cmd_files),)
-	include $(cmd_files)
-endif
+__headers: $(check-files)
+	@:
 
-endif # skip-inst
+endif
 
 PHONY += FORCE
-FORCE: ;
+FORCE:
 
 .PHONY: $(PHONY)