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>

4 files changed, 4 insertions, 4 deletions

diff --git a/drivers/net/ethernet/aquantia/atlantic/Makefile b/drivers/net/ethernet/aquantia/atlantic/Makefile
index 8ebcc68e807f..f6a96931c89a 100644
--- a/drivers/net/ethernet/aquantia/atlantic/Makefile
+++ b/drivers/net/ethernet/aquantia/atlantic/Makefile
@@ -8,7 +8,7 @@
 
 obj-$(CONFIG_AQTION) += atlantic.o
 
-ccflags-y += -I$(srctree)/$(src)
+ccflags-y += -I$(src)
 
 atlantic-objs := aq_main.o \
 	aq_nic.o \
diff --git a/drivers/net/ethernet/chelsio/libcxgb/Makefile b/drivers/net/ethernet/chelsio/libcxgb/Makefile
index aa79264e72ba..fbedc31674b3 100644
--- a/drivers/net/ethernet/chelsio/libcxgb/Makefile
+++ b/drivers/net/ethernet/chelsio/libcxgb/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
-ccflags-y := -I $(srctree)/$(src)/../cxgb4
+ccflags-y := -I $(src)/../cxgb4
 
 obj-$(CONFIG_CHELSIO_LIB) += libcxgb.o
 
diff --git a/drivers/net/ethernet/fungible/funeth/Makefile b/drivers/net/ethernet/fungible/funeth/Makefile
index 646d69595b4f..d51e4c2b4a1a 100644
--- a/drivers/net/ethernet/fungible/funeth/Makefile
+++ b/drivers/net/ethernet/fungible/funeth/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
 
-ccflags-y += -I$(srctree)/$(src)/../funcore -I$(srctree)/$(src)
+ccflags-y += -I$(src)/../funcore -I$(src)
 
 obj-$(CONFIG_FUN_ETH) += funeth.o
 
diff --git a/drivers/net/ethernet/hisilicon/hns3/Makefile b/drivers/net/ethernet/hisilicon/hns3/Makefile
index e214bfaece1f..8e9293e57bfd 100644
--- a/drivers/net/ethernet/hisilicon/hns3/Makefile
+++ b/drivers/net/ethernet/hisilicon/hns3/Makefile
@@ -3,7 +3,7 @@
 # Makefile for the HISILICON network device drivers.
 #
 
-ccflags-y += -I$(srctree)/$(src)
+ccflags-y += -I$(src)
 ccflags-y += -I$(srctree)/drivers/net/ethernet/hisilicon/hns3/hns3pf
 ccflags-y += -I$(srctree)/drivers/net/ethernet/hisilicon/hns3/hns3vf
 ccflags-y += -I$(srctree)/drivers/net/ethernet/hisilicon/hns3/hns3_common