kbuild: introduce hostprogs-always-y and userprogs-always-y

To build host programs, you need to add the program names to 'hostprogs'
to use the necessary build rule, but it is not enough to build them
because there is no dependency.

There are two types of host programs: built as the prerequisite of
another (e.g. gen_crc32table in lib/Makefile), or always built when
Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile).

The latter is typical in Makefiles under scripts/, which contains host
programs globally used during the kernel build. To build them, you need
to add them to both 'hostprogs' and 'always-y'.

This commit adds hostprogs-always-y as a shorthand.

The same applies to user programs. net/bpfilter/Makefile builds
bpfilter_umh on demand, hence always-y is unneeded. In contrast,
programs under samples/ are added to both 'userprogs' and 'always-y'
so they are always built when Kbuild visits the Makefiles.

userprogs-always-y works as a shorthand.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

12 files changed, 12 insertions, 27 deletions

diff --git a/samples/auxdisplay/Makefile b/samples/auxdisplay/Makefile
index dbdf939af94a..19d5568938c3 100644
--- a/samples/auxdisplay/Makefile
+++ b/samples/auxdisplay/Makefile
@@ -1,3 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0
-userprogs := cfag12864b-example
-always-y := $(userprogs)
+userprogs-always-y += cfag12864b-example
diff --git a/samples/binderfs/Makefile b/samples/binderfs/Makefile
index 989e4badaee2..629e43b9b129 100644
--- a/samples/binderfs/Makefile
+++ b/samples/binderfs/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-userprogs := binderfs_example
-always-y := $(userprogs)
+userprogs-always-y += binderfs_example
 
 userccflags += -I usr/include
diff --git a/samples/connector/Makefile b/samples/connector/Makefile
index 50cb40e09a7b..d98a9e047c11 100644
--- a/samples/connector/Makefile
+++ b/samples/connector/Makefile
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_SAMPLE_CONNECTOR) += cn_test.o
 
-userprogs := ucon
-always-$(CONFIG_CC_CAN_LINK) := $(userprogs)
+userprogs-always-$(CONFIG_CC_CAN_LINK) += ucon
 
 userccflags += -I usr/include
diff --git a/samples/hidraw/Makefile b/samples/hidraw/Makefile
index d2c77ed60b39..594d989e5486 100644
--- a/samples/hidraw/Makefile
+++ b/samples/hidraw/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-userprogs := hid-example
-always-y := $(userprogs)
+userprogs-always-y += hid-example
 
 userccflags += -I usr/include
diff --git a/samples/mei/Makefile b/samples/mei/Makefile
index 329411f82369..c54b8a0ab04e 100644
--- a/samples/mei/Makefile
+++ b/samples/mei/Makefile
@@ -1,7 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 # Copyright (c) 2012-2019, Intel Corporation. All rights reserved.
-
-userprogs := mei-amt-version
-always-y := $(userprogs)
+userprogs-always-y += mei-amt-version
 
 userccflags += -I usr/include
diff --git a/samples/pidfd/Makefile b/samples/pidfd/Makefile
index 6e5b67e648c2..9754e2d81f70 100644
--- a/samples/pidfd/Makefile
+++ b/samples/pidfd/Makefile
@@ -1,6 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-
-usertprogs := pidfd-metadata
-always-y := $(userprogs)
+usertprogs-always-y += pidfd-metadata
 
 userccflags += -I usr/include
diff --git a/samples/seccomp/Makefile b/samples/seccomp/Makefile
index 75916c23e416..c85ae0ed8342 100644
--- a/samples/seccomp/Makefile
+++ b/samples/seccomp/Makefile
@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
-userprogs := bpf-fancy dropper bpf-direct user-trap
+userprogs-always-y += bpf-fancy dropper bpf-direct user-trap
 
 bpf-fancy-objs := bpf-fancy.o bpf-helper.o
 
 userccflags += -I usr/include
-
-always-y := $(userprogs)
diff --git a/samples/timers/Makefile b/samples/timers/Makefile
index 15c7ddbc8c51..e6836cdea4e2 100644
--- a/samples/timers/Makefile
+++ b/samples/timers/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-userprogs := hpet_example
-always-y := $(userprogs)
+userprogs-always-y += hpet_example
 
 userccflags += -I usr/include
diff --git a/samples/uhid/Makefile b/samples/uhid/Makefile
index 9e652fc34103..0aa424ec4899 100644
--- a/samples/uhid/Makefile
+++ b/samples/uhid/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-userprogs := uhid-example
-always-y := $(userprogs)
+userprogs-always-y += uhid-example
 
 userccflags += -I usr/include
diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
index 00b6824f9237..6377a678134a 100644
--- a/samples/vfs/Makefile
+++ b/samples/vfs/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-userprogs := test-fsmount test-statx
-always-y := $(userprogs)
+userprogs-always-y += test-fsmount test-statx
 
 userccflags += -I usr/include
diff --git a/samples/watch_queue/Makefile b/samples/watch_queue/Makefile
index 792b22f593cf..c0db3a6bc524 100644
--- a/samples/watch_queue/Makefile
+++ b/samples/watch_queue/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-userprogs := watch_test
-always-y := $(userprogs)
+userprogs-always-y += watch_test
 
 userccflags += -I usr/include
diff --git a/samples/watchdog/Makefile b/samples/watchdog/Makefile
index 17384cfb387e..ab39d23dc96b 100644
--- a/samples/watchdog/Makefile
+++ b/samples/watchdog/Makefile
@@ -1,3 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0
-userprogs := watchdog-simple
-always-y := $(userprogs)
+userprogs-always-y += watchdog-simple