From ac9f9a916691495666ab6e990ec061620fdb770d Mon Sep 17 00:00:00 2001
From: Elliot Berman <eberman@codeaurora.org>
Date: Tue, 19 Jan 2021 17:48:07 -0800
Subject: [PATCH] Kbuild: Support nested composite objects

Kbuild composite object only supports one level of composite objects.
That is, a composite object may only be composed of real compilable
objects. A composite object may not itself be composed of other
composite objects.

As a simple example, the following Kbuild description is not supported:

bar-a-y := a/bar0.o a/bar1.o
bar-b-y := b/bar2.o b/bar3.o

foo-objs := bar-a.o bar-b.o

obj-m += foo.o

Add such support by recursively searching for composite objects and
listing them in $(multi-used-*) and $(real-obj-*).

Change-Id: I59df994237e27bf54d11034ff871442938050313
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Jeff Johnson <jjohnson@codeaurora.org>
---
 Makefile             | 4 ++++
 scripts/Makefile.lib | 7 +++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 0fb38663ccde..af6024e31374 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,10 @@ SUBLEVEL = 61
 EXTRAVERSION =
 NAME = Kleptomaniac Octopus
 
+# indicate that change "Kbuild: Support nested composite objects" is
+# present in the kernel so that out-of-tree modules can act upon it
+export KERNEL_SUPPORTS_NESTED_COMPOSITES := y
+
 # *DOCUMENTATION*
 # To see a list of typical targets execute "make help"
 # More info can be located in ./README
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index ecf084bf1a95..b0c8d7a962e5 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -44,7 +44,8 @@ subdir-ym	:= $(sort $(subdir-y) $(subdir-m))
 # Expand $(foo-objs) $(foo-y) by calling $(call suffix-search,foo.o,-objs -y)
 suffix-search = $(foreach s,$(2),$($(1:.o=$s)))
 # If $(foo-objs), $(foo-y), $(foo-m), or $(foo-) exists, foo.o is a composite object
-multi-search = $(sort $(foreach m,$(1), $(if $(strip $(call suffix-search,$(m),$(2) -)), $(m))))
+multi-search = $(sort $(foreach m,$(1),$(if $(strip $(call suffix-search,$(m),$(2) -)),\
+	$(m) $(call multi-search,$(filter-out $(m),$(call suffix-search,$(m),$(2))),$(2)))))
 multi-used-y := $(call multi-search,$(obj-y),-objs -y)
 multi-used-m := $(call multi-search,$(obj-m),-objs -y -m)
 multi-used   := $(multi-used-y) $(multi-used-m)
@@ -55,7 +56,9 @@ subdir-obj-y := $(filter %/built-in.a, $(obj-y))
 
 # Replace multi-part objects by their individual parts,
 # including built-in.a from subdirectories
-real-search = $(foreach m,$(1), $(if $(strip $(call suffix-search,$(m),$(2) -)),$(call suffix-search,$(m),$(2)),$(m)))
+real-search = $(foreach m,$(1), $(if $(strip $(call suffix-search,$(m),$(2) -)), \
+	$(filter $(m),$(call suffix-search,$(m),$(2))) $(call real-search,$(filter-out $(m),$(call suffix-search,$(m),$(2))),$(2)),\
+	$(m)))
 real-obj-y := $(call real-search, $(obj-y),-objs -y)
 real-obj-m := $(call real-search, $(obj-m),-objs -y -m)