[LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent@gmail.com]

Hi Piotr,

On Mon, 4 May 2026 12:17:36 +0200, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test
>
> Verify for all online logical CPUs that their highest performance value are
> the same for HWP Capability MSR 0x771 and CPPC sysfs file.

The body describes what the test does but not why it is needed. Please
add at least one sentence explaining the motivation — e.g. a known
inconsistency, a kernel regression, or a new interface being validated.

[...]

> +		snprintf(path, sizeof(path), "/dev/cpu/%d/msr", i);
> +		int fd = SAFE_OPEN(path, O_RDONLY);
> +
> +		SAFE_PREAD(1, fd, &msr_highest_perf, sizeof(msr_highest_perf), MSR_HWP_CAPABILITIES);
> +		SAFE_CLOSE(fd);

If SAFE_PREAD aborts via tst_brk(), cleanup() is called but fd is never
closed because it is a loop-local variable with no cleanup handler.
Promote fd to a static (initialized to -1) and add a cleanup() that
guards with `if (fd != -1) SAFE_CLOSE(fd);`.

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