kbuild: do not redirect the first prerequisite for filechk

Currently, filechk unconditionally opens the first prerequisite and
redirects it as the stdin of a filechk_* rule.  Hence, every target
using $(call filechk,...) must list something as the first prerequisite
even if it is unneeded.

'< $<' is actually unneeded in most cases.  Each rule can explicitly
adds it if necessary.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1117,7 +1117,7 @@ define filechk_version.h
 	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
 endef
 
-$(version_h): $(srctree)/Makefile FORCE
+$(version_h): FORCE
 	$(call filechk,version.h)
 	$(Q)rm -f $(old_version_h)
 

arch/s390/kernel/syscalls/Makefile

@@ -25,15 +25,15 @@ _dummy := $(shell [ -d '$(uapi)' ] || mkdir -p '$(uapi)') \
 	  $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
 
 define filechk_syshdr
-	$(CONFIG_SHELL) '$(systbl)' -H -a $(syshdr_abi_$(basetarget)) -f "$2"
+	$(CONFIG_SHELL) '$(systbl)' -H -a $(syshdr_abi_$(basetarget)) -f "$2" < $<
 endef
 
 define filechk_sysnr
-	$(CONFIG_SHELL) '$(systbl)' -N -a $(sysnr_abi_$(basetarget))
+	$(CONFIG_SHELL) '$(systbl)' -N -a $(sysnr_abi_$(basetarget)) < $<
 endef
 
 define filechk_syscalls
-	$(CONFIG_SHELL) '$(systbl)' -S
+	$(CONFIG_SHELL) '$(systbl)' -S < $<
 endef
 
 syshdr_abi_unistd_32 := common,32

arch/um/Makefile

@@ -169,7 +169,7 @@ define filechk_gen-asm-offsets
          echo " *"; \
          echo " */"; \
          echo ""; \
-         sed -ne "/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"; \
+         sed -ne "/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}" < $<; \
          echo ""; )
 endef
 

scripts/Kbuild.include

@@ -56,7 +56,7 @@ kecho := $($(quiet)kecho)
 define filechk
 	$(Q)set -e;				\
 	mkdir -p $(dir $@);			\
-	$(filechk_$(1)) < $< > $@.tmp;		\
+	$(filechk_$(1)) > $@.tmp;		\
 	if [ -r $@ ] && cmp -s $@ $@.tmp; then	\
 		rm -f $@.tmp;			\
 	else					\

scripts/Makefile.lib

@@ -415,7 +415,7 @@ define filechk_offsets
 	 echo " * This file was generated by Kbuild"; \
 	 echo " */"; \
 	 echo ""; \
-	 sed -ne $(sed-offsets); \
+	 sed -ne $(sed-offsets) < $<; \
 	 echo ""; \
 	 echo "#endif" )
 endef