bpfilter: check compiler capability in Kconfig

With the brand-new syntax extension of Kconfig, we can directly
check the compiler capability in the configuration phase.

If the cc-can-link.sh fails, the BPFILTER_UMH is automatically
hidden by the dependency.

I also deleted 'default n', which is no-op.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Makefile b/Makefile
index c913259..e1bd4c3 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -507,11 +507,6 @@ ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLA
   KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
 endif
 
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/cc-can-link.sh $(CC)), y)
-  CC_CAN_LINK := y
-  export CC_CAN_LINK
-endif
-
 # The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
 # Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
 # CC_VERSION_TEXT is referenced from Kconfig (so it needs export),

diff --git a/net/Makefile b/net/Makefile
index 13ec0d5..bdaf539 100644 (file)
--- a/net/Makefile
+++ b/net/Makefile
@@ -20,11 +20,7 @@ obj-$(CONFIG_TLS)            += tls/
 obj-$(CONFIG_XFRM)             += xfrm/
 obj-$(CONFIG_UNIX)             += unix/
 obj-$(CONFIG_NET)              += ipv6/
-ifneq ($(CC_CAN_LINK),y)
-$(warning CC cannot link executables. Skipping bpfilter.)
-else
 obj-$(CONFIG_BPFILTER)         += bpfilter/
-endif
 obj-$(CONFIG_PACKET)           += packet/
 obj-$(CONFIG_NET_KEY)          += key/
 obj-$(CONFIG_BRIDGE)           += bridge/

diff --git a/net/bpfilter/Kconfig b/net/bpfilter/Kconfig
index a948b07..76deb66 100644 (file)
--- a/net/bpfilter/Kconfig
+++ b/net/bpfilter/Kconfig
@@ -1,6 +1,5 @@
 menuconfig BPFILTER
        bool "BPF based packet filtering framework (BPFILTER)"
-       default n
        depends on NET && BPF && INET
        help
          This builds experimental bpfilter framework that is aiming to
@@ -9,6 +8,7 @@ menuconfig BPFILTER
 if BPFILTER
 config BPFILTER_UMH
        tristate "bpfilter kernel module with user mode helper"
+       depends on $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
        default m
        help
          This builds bpfilter kernel module with embedded user mode helper

diff --git a/scripts/cc-can-link.sh b/scripts/cc-can-link.sh
index 208eb28..6efcead 100755 (executable)
--- a/scripts/cc-can-link.sh
+++ b/scripts/cc-can-link.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
-cat << "END" | $@ -x c - -o /dev/null >/dev/null 2>&1 && echo "y"
+cat << "END" | $@ -x c - -o /dev/null >/dev/null 2>&1
 #include <stdio.h>
 int main(void)
 {