[LTP] cpufreq.c: add new test for cpufreq sysfs interface validation

[linuxtestproject.agent@gmail.com]

Hi Piotr,

On Wed, 6 May 2026, Piotr Kubaj wrote:
> cpufreq.c: add new test for cpufreq sysfs interface validation

> +	tst_res(TDEBUG, "Checking whether scaling_available_governors contains \"performance\" and \"schedutil\" after switching /sys/devices/system/cpu/intel_pstate/status to \"passive\"");
> +	snprintf(path, sizeof(path), "/sys/devices/system/cpu/intel_pstate/status");
> +	SAFE_FILE_PRINTF(path, "passive");
> +
> +	for (int i = 0; i < nproc; i++) {
> +		...
> +		SAFE_FILE_PRINTF(path, "schedutil");
> +		...
> +	}
> +}

run() exits with intel_pstate/status still "passive" and each CPU's
scaling_governor still "schedutil". On the second iteration (-i 2) the
status check fires TFAIL immediately, and the governor branch hits
tst_brk(TBROK, "Unknown scaling_governor: schedutil").

Restore the status to "active" and the governors to previous_scaling_governor[i]
at the end of run() before it returns.

[...]

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