Re: [PATCH bpf-next] selftests/bpf: Tolerate libarena skeleton failures under BPF_STRICT_BUILD=0

[Eduard Zingerman <eddyz87@gmail.com>]

On Fri, 2026-09-11 at 23:16 +0900, HyeongJun An wrote:
> The Makefile documents BPF_STRICT_BUILD=0 as tolerating any BPF object,
> skeleton, test object or benchmark failure so that the remaining tests
> still build.  Every skeleton rule honours that through
> $(if $(PERMISSIVE),...), except the three that build the libarena
> skeletons.  Those invoke a sub-make with no guard, so a libarena failure
> is fatal even in permissive mode.
> 
> With a libarena source that fails to compile, BPF_STRICT_BUILD=0 stops at
> 
>   make: *** [libarena/libarena.skel.h] Error 2
> 
> while an ordinary program failing the same way prints SKIP-BPF and the
> build carries on.
> 
> Guard the three sub-makes the way the other skeleton rules are guarded.
> The build then prints SKIP-SKEL and continues, and test_progs,
> test_progs-no_alu32, test_progs-cpuv4 and bench all link.  Nothing
> downstream needs a change, because the missing skeleton drops out through
> the existing permissive paths and libarena.test.o is reported as
> SKIP-TEST.  The default BPF_STRICT_BUILD=1 still fails on the same input.
> 
> Fixes: a6850fa388f6 ("selftests/bpf: Add BPF_STRICT_BUILD toggle")
> Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
> Assisted-by: Claude:claude-opus-5
> ---

Why is this change necessary?
The whole PERMISSIVE thing is quite ugly and I regret not being
involved in it's review.

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