kbuild: check module name conflict for external modules as well

If there are multiple modules with the same name in the same external
module tree, there is ambiguity about which one will be loaded, and
very likely something odd is happening.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Makefile

@@ -1459,10 +1459,6 @@ endif
 PHONY += modules
 modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare
 
-PHONY += modules_check
-modules_check: modules.order
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
-
 cmd_modules_order = $(AWK) '!x[$$0]++' $(real-prereqs) > $@
 
 modules.order: $(subdir-modorder) FORCE
@@ -1775,9 +1771,13 @@ PHONY += modules modules_install
 
 ifdef CONFIG_MODULES
 
-modules: $(MODORDER)
+modules: modules_check
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
+PHONY += modules_check
+modules_check: $(MODORDER)
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules-check.sh $<
+
 quiet_cmd_depmod = DEPMOD  $(MODLIB)
       cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
                    $(KERNELRELEASE)

scripts/modules-check.sh

@@ -13,10 +13,10 @@ exit_code=0
 # Check uniqueness of module names
 check_same_name_modules()
 {
-	for m in $(sed 's:.*/::' $1 | sort | uniq -d)
+	for m in $(sed 's:.*/::' "$1" | sort | uniq -d)
 	do
 		echo "error: the following would cause module name conflict:" >&2
-		sed -n "/\/$m/s:^:  :p" modules.order >&2
+		sed -n "/\/$m/s:^:  :p" "$1" >&2
 		exit_code=1
 	done
 }