[PATCH v2 1/2] kbuild: get rid of duplication in the first line of *.mod files

[Masahiro Yamada <masahiroy@kernel.org>]

The first line of *.mod lists the object files that consist of the
module. This may contain duplication if the same object is added
multiple times, like this:

  obj-m := foo.o
  foo-$(CONFIG_FOO1_X) += foo1.o
  foo-$(CONFIG_FOO1_Y) += foo1.o
  foo-$(CONFIG_FOO2_X) += foo2.o
  foo-$(CONFIG_FOO2_Y) += foo2.o

This is probably not a big deal. As far as I know, the only small
problem is scripts/mod/sumversion.c parses the same file over again.
This can be avoided by adding $(sort ...). It has a side-effect that
sorts the objects alphabetically, but it is not a big deal, either.

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

Changes in v2:
  - new patch

 scripts/Makefile.build | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index b734ac8a654e..d8445b696d5b 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -265,8 +265,10 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 
+multi-m-prereqs = $(sort $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)))
+
 cmd_mod = { \
-	echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
+	echo $(if $(multi-m-prereqs), $(multi-m-prereqs), $(@:.mod=.o)); \
 	$(cmd_undef_syms); \
 	} > $@
 
-- 
2.17.1