[PATCH 4.9 21/31] kbuild: Fix include path in scripts/Makefile.modpost

[Greg Kroah-Hartman]

From: Jing Leng <jleng@xxxxxxxxxxxxx>

commit 23a0cb8e3225122496bfa79172005c587c2d64bf upstream.

When building an external module, if users don't need to separate the
compilation output and source code, they run the following command:
"make -C $(LINUX_SRC_DIR) M=$(PWD)". At this point, "$(KBUILD_EXTMOD)"
and "$(src)" are the same.

If they need to separate them, they run "make -C $(KERNEL_SRC_DIR)
O=$(KERNEL_OUT_DIR) M=$(OUT_DIR) src=$(PWD)". Before running the
command, they need to copy "Kbuild" or "Makefile" to "$(OUT_DIR)" to
prevent compilation failure.

So the kernel should change the included path to avoid the copy operation.

Signed-off-by: Jing Leng <jleng@xxxxxxxxxxxxx>
[masahiro: I do not think "M=$(OUT_DIR) src=$(PWD)" is the official way,
but this patch is a nice clean up anyway.]
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
[nsc: updated context for v4.19]
Signed-off-by: Nicolas Schier <n.schier@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 scripts/Makefile.modpost |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -50,8 +50,7 @@ obj := $(KBUILD_EXTMOD)
 src := $(obj)
 
 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
-include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
-             $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
+include $(if $(wildcard $(src)/Kbuild), $(src)/Kbuild, $(src)/Makefile)
 endif
 
 include scripts/Makefile.lib