kbuild: use $(src) instead of $(srctree)/$(src) for source directory

Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:

    src := $(obj)

When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.

This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.

To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.

Going forward, the variables used in Makefiles will have the following
meanings:

  $(obj)     - directory in the object tree
  $(src)     - directory in the source tree  (changed by this commit)
  $(objtree) - the top of the kernel object tree
  $(srctree) - the top of the kernel source tree

Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/Makefile b/lib/Makefile
index ffc6b2341b45..27baa6e6daa8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -352,7 +352,7 @@ $(obj)/oid_registry_data.c: $(srctree)/include/linux/oid_registry.h \
 	$(call cmd,build_OID_registry)
 
 quiet_cmd_build_OID_registry = GEN     $@
-      cmd_build_OID_registry = perl $(srctree)/$(src)/build_OID_registry $< $@
+      cmd_build_OID_registry = perl $(src)/build_OID_registry $< $@
 
 clean-files	+= oid_registry_data.c
 
@@ -412,8 +412,8 @@ obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 obj-$(CONFIG_FIRMWARE_TABLE) += fw_table.o
 
 # FORTIFY_SOURCE compile-time behavior tests
-TEST_FORTIFY_SRCS = $(wildcard $(srctree)/$(src)/test_fortify/*-*.c)
-TEST_FORTIFY_LOGS = $(patsubst $(srctree)/$(src)/%.c, %.log, $(TEST_FORTIFY_SRCS))
+TEST_FORTIFY_SRCS = $(wildcard $(src)/test_fortify/*-*.c)
+TEST_FORTIFY_LOGS = $(patsubst $(src)/%.c, %.log, $(TEST_FORTIFY_SRCS))
 TEST_FORTIFY_LOG = test_fortify.log
 
 quiet_cmd_test_fortify = TEST    $@