kbuild: simplify scripts/headers_install.sh

Now that headers_install.sh is invoked per file, remove the for-loop
in the shell script.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/Makefile.headersinst

@@ -58,7 +58,7 @@ $(if $(new-dirs), $(shell mkdir -p $(new-dirs)))
 ifndef HDRCHECK
 
 quiet_cmd_install = HDRINST $@
-      cmd_install = $(CONFIG_SHELL) $(srctree)/scripts/headers_install.sh $(@D) $(<D) $(@F)
+      cmd_install = $(CONFIG_SHELL) $(srctree)/scripts/headers_install.sh $< $@
 
 $(src-headers): $(dst)/%.h: $(src)/%.h $(srctree)/scripts/headers_install.sh FORCE
 	$(call if_changed,install)

scripts/headers_install.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
-if [ $# -lt 2 ]
+if [ $# -ne 2 ]
 then
-	echo "Usage: headers_install.sh OUTDIR SRCDIR [FILES...]"
+	echo "Usage: headers_install.sh INFILE OUTFILE"
 	echo
 	echo "Prepares kernel header files for use by user space, by removing"
 	echo "all compiler.h definitions and #includes, removing any"
 	echo "#ifdef __KERNEL__ sections, and putting __underscores__ around"
 	echo "asm/inline/volatile keywords."
 	echo
-	echo "OUTDIR: directory to write each userspace header FILE to."
-	echo "SRCDIR: source directory where files are picked."
-	echo "FILES:  list of header files to operate on."
+	echo "INFILE: header file to operate on"
+	echo "OUTFILE: output file which the processed header is writen to"
 
 	exit 1
 fi
 
 # Grab arguments
+INFILE=$1
+OUTFILE=$2
+TMPFILE=$OUTFILE.tmp
 
-OUTDIR="$1"
-shift
-SRCDIR="$1"
-shift
+trap 'rm -f $OUTFILE $TMPFILE' EXIT
 
-# Iterate through files listed on command line
+sed -E -e '
+	s/([[:space:](])(__user|__force|__iomem)[[:space:]]/\1/g
+	s/__attribute_const__([[:space:]]|$)/\1/g
+	s@^#include <linux/compiler(|_types).h>@@
+	s/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g
+	s/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g
+	s@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @
+' $INFILE > $TMPFILE || exit 1
 
-FILE=
-trap 'rm -f "$OUTDIR/$FILE" "$OUTDIR/$FILE.sed"' EXIT
-for i in "$@"
-do
-	FILE="$(basename "$i")"
-	sed -E \
-		-e 's/([[:space:](])(__user|__force|__iomem)[[:space:]]/\1/g' \
-		-e 's/__attribute_const__([[:space:]]|$)/\1/g' \
-		-e 's@^#include <linux/compiler(|_types).h>@@' \
-		-e 's/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g' \
-		-e 's/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g' \
-		-e 's@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @' \
-		"$SRCDIR/$i" > "$OUTDIR/$FILE.sed" || exit 1
-	scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ "$OUTDIR/$FILE.sed" \
-		> "$OUTDIR/$FILE"
-	[ $? -gt 1 ] && exit 1
-	rm -f "$OUTDIR/$FILE.sed"
-done
+scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ $TMPFILE > $OUTFILE
+[ $? -gt 1 ] && exit 1
+
+rm -f $TMPFILE
 trap - EXIT