kbuild: add phony targets to ./Kbuild

missing-syscalls and old-atomics are meant to be phony targets.
Adding them to always-y is odd. (always-y should generate something).

Add a new phony target 'prepare', which depends on all the other.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Kbuild

@@ -2,18 +2,18 @@
 #
 # Kbuild for top-level directory of the kernel
 
-#####
+# Prepare global headers and check sanity before descending into sub-directories
+# ---------------------------------------------------------------------------
+
 # Generate bounds.h
 
 bounds-file := include/generated/bounds.h
 
-always-y := $(bounds-file)
 targets := kernel/bounds.s
 
 $(bounds-file): kernel/bounds.s FORCE
 	$(call filechk,offsets,__LINUX_BOUNDS_H__)
 
-#####
 # Generate timeconst.h
 
 timeconst-file := include/generated/timeconst.h
@@ -23,12 +23,10 @@ filechk_gentimeconst = echo $(CONFIG_HZ) | bc -q $<
 $(timeconst-file): kernel/time/timeconst.bc FORCE
 	$(call filechk,gentimeconst)
 
-#####
 # Generate asm-offsets.h
 
 offsets-file := include/generated/asm-offsets.h
 
-always-y += $(offsets-file)
 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 
 arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file)
@@ -36,24 +34,26 @@ arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file)
 $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
 	$(call filechk,offsets,__ASM_OFFSETS_H__)
 
-#####
 # Check for missing system calls
 
-always-y += missing-syscalls
-
 quiet_cmd_syscalls = CALL    $<
       cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
 
-missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
+PHONY += missing-syscalls
+missing-syscalls: scripts/checksyscalls.sh $(offsets-file)
 	$(call cmd,syscalls)
 
-#####
 # Check atomic headers are up-to-date
 
-always-y += old-atomics
-
 quiet_cmd_atomics = CALL    $<
       cmd_atomics = $(CONFIG_SHELL) $<
 
-old-atomics: scripts/atomic/check-atomics.sh FORCE
+PHONY += old-atomics
+old-atomics: scripts/atomic/check-atomics.sh
 	$(call cmd,atomics)
+
+# A phony target that depends on all the preparation targets
+
+PHONY += prepare
+prepare: $(offsets-file) missing-syscalls old-atomics
+	@:

Makefile

@@ -1202,7 +1202,7 @@ archprepare: outputmakefile archheaders archscripts scripts include/config/kerne
 
 prepare0: archprepare
 	$(Q)$(MAKE) $(build)=scripts/mod
-	$(Q)$(MAKE) $(build)=.
+	$(Q)$(MAKE) $(build)=. prepare
 
 # All the preparing..
 prepare: prepare0