[PATCH v2] kbuild: deb-pkg: remove the fakeroot builds support

[Masahiro Yamada <masahiroy@kernel.org>]

In 2017, the dpkg suite introduced the rootless builds support with the
following commits:

  - 2436807c87b0 ("dpkg-deb: Add support for rootless builds")
  - fca1bfe84068 ("dpkg-buildpackage: Add support for rootless builds")

This feature is available in the default dpkg on Debian 10 and Ubuntu
20.04.

Remove the old method.

Additionally, export DEB_RULES_REQUIRES_ROOT=no in case debian/rules is
invoked without dpkg-buildpackage. This change aligns with the Debian
kernel commit 65206e29f378 ("Allow to run d/rules.real without root").
While the upstream kernel currently does not run dh_testroot, it may
be useful in the future.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
  - add DEB_RULES_REQUIRES_ROOT=no to debian/rules

 scripts/Makefile.package     | 4 +---
 scripts/package/builddeb     | 8 +-------
 scripts/package/debian/rules | 2 ++
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 0c3adc48dfe8..a81dfb1f5181 100644
--- a/scripts/Makefile.package
+++ b/scripts/Makefile.package
@@ -109,8 +109,6 @@ debian-orig: linux.tar$(debian-orig-suffix) debian
 		cp $< ../$(orig-name); \
 	fi
 
-KBUILD_PKG_ROOTCMD ?= 'fakeroot -u'
-
 PHONY += deb-pkg srcdeb-pkg bindeb-pkg
 
 deb-pkg:    private build-type := source,binary
@@ -125,7 +123,7 @@ deb-pkg srcdeb-pkg bindeb-pkg:
 	$(if $(findstring source, $(build-type)), \
 		--unsigned-source --compression=$(KDEB_SOURCE_COMPRESS)) \
 	$(if $(findstring binary, $(build-type)), \
-		-R'$(MAKE) -f debian/rules' -j1 -r$(KBUILD_PKG_ROOTCMD) -a$$(cat debian/arch), \
+		-R'$(MAKE) -f debian/rules' -j1 -a$$(cat debian/arch), \
 		--no-check-builddeps) \
 	$(DPKG_FLAGS))
 
diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index d7dd0d04c70c..2fe51e6919da 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -36,19 +36,13 @@ create_package() {
 	sh -c "cd '$pdir'; find . -type f ! -path './DEBIAN/*' -printf '%P\0' \
 		| xargs -r0 md5sum > DEBIAN/md5sums"
 
-	# Fix ownership and permissions
-	if [ "$DEB_RULES_REQUIRES_ROOT" = "no" ]; then
-		dpkg_deb_opts="--root-owner-group"
-	else
-		chown -R root:root "$pdir"
-	fi
 	# a+rX in case we are in a restrictive umask environment like 0077
 	# ug-s in case we build in a setuid/setgid directory
 	chmod -R go-w,a+rX,ug-s "$pdir"
 
 	# Create the package
 	dpkg-gencontrol -p$pname -P"$pdir"
-	dpkg-deb $dpkg_deb_opts ${KDEB_COMPRESS:+-Z$KDEB_COMPRESS} --build "$pdir" ..
+	dpkg-deb --root-owner-group ${KDEB_COMPRESS:+-Z$KDEB_COMPRESS} --build "$pdir" ..
 }
 
 install_linux_image () {
diff --git a/scripts/package/debian/rules b/scripts/package/debian/rules
index 3dafa9496c63..f23d97087948 100755
--- a/scripts/package/debian/rules
+++ b/scripts/package/debian/rules
@@ -5,6 +5,8 @@ include debian/rules.vars
 
 srctree ?= .
 
+export DEB_RULES_REQUIRES_ROOT := no
+
 ifneq (,$(filter-out parallel=1,$(filter parallel=%,$(DEB_BUILD_OPTIONS))))
     NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
     MAKEFLAGS += -j$(NUMJOBS)
-- 
2.40.1