Re: [PATCH net 1/2] selftests: netfilter: use KHDR_INCLUDES in CFLAGS

Hi Ilya,

On 04/09/2026 18:41, Ilya Maximets wrote:

On 9/4/26 6:13 PM, Matthieu Baerts (NGI0) wrote:

quoted

KHDR_INCLUDES is typically used to include headers from the kernel
source directory instead of only relying on the ones from the host: they
can be missing or outdated.

The kselftest doc recommends assigning KHDR_INCLUDES to CFLAGS in a
target Makefile. lib.mk will set KHDR_INCLUDES to "-isystem
$(top_srcdir)/usr/include" if the user didn't set it, e.g. if the kernel
was built in a different build directory.

Other net targets have KHDR_INCLUDES added to their CFLAGS.

Fixes: 3f189349e52a ("selftests: netfilter: move to net subdir")

I think, this should point to a commit that added the first C test:

Fixes: a64d558d8cf9 ("selftests: netfilter: add nfqueue test case")

Good catch! I saw that CFLAGS was set before, but indeed, KHDR_INCLUDES
wasn't.

If we want to change the Fixes tag, we will also need to add:

Fixes: a52540522c95 ("selftests/landlock: Fix out-of-tree builds")

Which is when KHDR_INCLUDES got introduced. (Or it is enough with the
current Fixes tag, as long as it is included in the last stable version:
that's probably enough for CIs using kselftests from the last stable
version on older ones.)

@Net maintainers: please tell me if I need to change the Fixes tag in a v2.

quoted

Link: https://docs.kernel.org/dev-tools/kselftest.html#contributing-new-tests-details
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/netfilter/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/net/netfilter/Makefile b/tools/testing/selftests/net/netfilter/Makefile
index f88dd4ef8d26..df3c20c90f5d 100644
--- a/tools/testing/selftests/net/netfilter/Makefile
+++ b/tools/testing/selftests/net/netfilter/Makefile

@@ -2,6 +2,8 @@
 
 top_srcdir = ../../../../..
 
+CFLAGS += $(KHDR_INCLUDES)
+
 HOSTPKG_CONFIG := pkg-config
 MNL_CFLAGS := $(shell $(HOSTPKG_CONFIG) --cflags libmnl 2>/dev/null)
 MNL_LDLIBS := $(shell $(HOSTPKG_CONFIG) --libs libmnl 2>/dev/null || echo -lmnl)

This solves my problem with building netfilter tests locally with uAPI
modifications.  Beside the Fixes tag, LGTM.

Thank you for having checked!

Cheers,
Matt
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