Changes in Makefile

9779193e871b144e34ec4a3e50109b3778a51a69 - selftests/bpf: Fix test_kmods KDIR to honor O= and distro kernels

Tue, 02 Jun 2026 15:02:51 +0200

selftests/bpf: Fix test_kmods KDIR to honor O= and distro kernelstest_kmods/Makefile always pointed KDIR at the kernel source tree root,ignoring O= and KBUILD_OUTPUT. On distro kernels where the source tree hasnot been built, the Makefile had no fallback and would failunconditionally.When O= or KBUILD_OUTPUT is set and points at a prepared kernel builddirectory (one containing Module.symvers), pass it through so kbuild canlocate the correct build infrastructure (scripts, Kconfig, etc.). Notethat the module artifacts themselves still land in the M= directory,which is test_kmods/; O= only controls where kbuild finds its buildinfrastructure. Fall back to /lib/modules/$(uname -r)/build when neitheran explicit valid build directory nor an in-tree Module.symvers ispresent.A selftests-only O= value (one that does not contain Module.symvers, e.g.a private output directory) is intentionally not treated as a kernelbuild directory. Without this guard, a user invoking"make -C tools/testing/selftests/bpf O=/tmp/out" would have test_kmodstry to use /tmp/out as the kernel build dir and fail.The parent bpf/Makefile resolves O= and KBUILD_OUTPUT to absolute pathsbefore invoking the test_kmods sub-make. Without this, $(abspath ...)inside test_kmods/Makefile would resolve relative paths against thesub-make's CWD (test_kmods/) rather than the user's invocation directory.When O= is passed to kbuild, also pass KBUILD_OUTPUT=$(KMOD_O_VALID)explicitly. The parent invocation lifts KBUILD_OUTPUT into MAKEFLAGS asa command-line variable, which would otherwise suppress kbuild's own"KBUILD_OUTPUT := $(O)" assignment and cause it to use the inheritedKBUILD_OUTPUT instead of the validated O=.Guard both all and clean against a missing KDIR so the step is silentlyskipped rather than fatal. Make the parent Makefile's cp conditional so itdoes not abort when modules were not built.Signed-off-by: Ricardo B. Marlière Link: https://lore.kernel.org/r/20260602-selftests-bpf_misconfig-v12-2-27f898b3ba26@suse.comSigned-off-by: Alexei Starovoitov List of files: /linux/tools/testing/selftests/bpf/test_kmods/Makefile

15cf39221e89ad413c3cc2cb8f15a2487db2ba2f - selftests/bpf: Add stress test for rqspinlock in NMI

Sat, 27 Sep 2025 22:53:04 +0200

selftests/bpf: Add stress test for rqspinlock in NMIIntroduce a kernel module that will exercise lock acquisition in the NMIpath, and bias toward creating contention such that NMI waiters end upbeing non-head waiters. Prior to the rqspinlock fix made in the commit0d80e7f951be ("rqspinlock: Choose trylock fallback for NMI waiters"), itwas possible for the queueing path of non-head waiters to get stuck inNMI, which this stress test reproduces fairly easily with just 3 CPUs.Both AA and ABBA flavors are supported, and it will serve as a test casefor future fixes that address this corner case. More information aboutthe problem in question is available in the commit cited above. When thefix is reverted, this stress test will lock up the system.To enable this test automatically through the test_progs infrastructure,add a load_module_params API to exercise both AA and ABBA cases whenrunning the test.Note that the test runs for at most 5 seconds, and becomes a noop afterthat, in order to allow the system to make forward progress. Inaddition, CPU 0 is always kept untouched by the created threads andNMIs. The test will automatically scale to the number of availableonline CPUs.Note that at least 3 CPUs are necessary to run this test, hence skip theselftest in case the environment has less than 3 CPUs available.Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250927205304.199760-1-memxor@gmail.comSigned-off-by: Alexei Starovoitov List of files: /linux/tools/testing/selftests/bpf/test_kmods/Makefile

d6212d82bf26f3cbd30b84df064080dd98051ae9 - selftests/bpf: Consolidate kernel modules into common directory

Wed, 04 Dec 2024 14:28:26 +0100

selftests/bpf: Consolidate kernel modules into common directoryThe selftests build four kernel modules which use copy-pasted Makefiletargets. This is a bit messy, and doesn't scale so well when we add moremodules, so let's consolidate these rules into a single rule generatedfor each module name, and move the module sources into a singledirectory.To avoid parallel builds of the different modules stepping on eachother's toes during the 'modpost' phase of the Kbuild 'make modules',the module files should really be a grouped target. However, make onlyadded explicit support for grouped targets in version 4.3, which isnewer than the minimum version supported by the kernel. However, makeimplicitly treats pattern matching rules with multiple targets as agrouped target, so we can work around this by turning the rule into apattern matching target. We do this by replacing '.ko' with '%ko' in thetargets with subst().Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Andrii Nakryiko Acked-by: Viktor Malik Link: https://lore.kernel.org/bpf/20241204-bpf-selftests-mod-compile-v5-1-b96231134a49@redhat.com List of files: /linux/tools/testing/selftests/bpf/test_kmods/Makefile