linux-kernel - Re: [PATCH bpf-next v2 8/9] selftests/bpf: Add selftests for load-acquire and store-release instructions

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Message-ID: <1d2d919ae6848e2cf80b81ffe5f94fd31b8ea6ae.camel@gmail.com>
Date: Tue, 11 Feb 2025 12:15:25 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Peilin Ye <yepeilin@...gle.com>
Cc: bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, bpf@...f.org,
  Xu Kuohai <xukuohai@...weicloud.com>, David Vernet <void@...ifault.com>,
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Subject: Re: [PATCH bpf-next v2 8/9] selftests/bpf: Add selftests for
 load-acquire and store-release instructions

On Tue, 2025-02-11 at 19:09 +0000, Peilin Ye wrote:

[...]

> > Nit: why is dummy_test() necessary?
> 
> It's just to make it clear when these tests are (effectively) skipped.
> Otherwise, e.g. -cpuv4 runner with LLVM-18 on x86-64 would give:
> 
>   #518     verifier_load_acquire:OK
> 
> With dummy_test(), we would see:
> 
> (FWIW, for v3 I'm planning to change __description() to the following,
> since new tests no longer depend on __BPF_FEATURE_LOAD_ACQ_STORE_REL.)
> 
>   #518/1   verifier_load_acquire/Clang version < 18, or JIT does not support load-acquire; use a dummy test:OK
>   #518     verifier_load_acquire:OK
> 
> Commit 147c8f4470ee ("selftests/bpf: Add unit tests for new
> sign-extension load insns") did similar thing in verifier_ldsx.c.

I see, thank you for explaining.
We do have a concept of skipped tests in the test-suite,
but it is implemented by calling test__skip() from the prog_tests/<smth>.c.
This would translate as something like below in prog_tests/verifier.c:

	void test_verifier_store_release(void) {
	#if defined(ENABLE_ATOMICS_TESTS) && defined(__TARGET_ARCH_arm64)
		RUN(verifier_store_release);
	#else
		test__skip()
	#endif
	}

The number of tests skipped is printed after tests execution.
Up to you if you'd like to change it like that or not.