[igt-dev] [PATCH i-g-t 2/2] tests/perf: add test for disabled preemption stream

[Antonio Argenziano]

On 05/06/18 09:25, Lionel Landwerlin wrote:
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---

> +

Maybe a comment on what busy loop is trying to do would help the lazy 
reader :).

> +static uint32_t
> +busy_loop(uint32_t context, uint32_t duration_ns)
> +{
> +	struct drm_i915_gem_execbuffer2 execbuf;
> +	struct drm_i915_gem_exec_object2 obj[4];

> +
> +	for (i = 1 /* skip data_handle */; i < ARRAY_SIZE(obj); i++)
> +		gem_close(drm_fd, obj[i].handle);
> +
> +	return data_handle;
> +}
> +

> +
> +/*
> + * Verify that holding preemption is not available for normal users
> + * unless they perf_stream_paranoid is off.
> + */
> +static void
> +test_unprivileged_single_ctx_counters_disabled_preemption(void)
> +{
> +	igt_fork(child, 1) {
> +		write_u64_file("/proc/sys/dev/i915/perf_stream_paranoid", 1);
> +
> +		igt_drop_root();
> +
> +		igt_assert(!has_i915_perf_disable_preemption_support(drm_fd));

Shouldn't this assert the return code from the IOCTL is -EPERM?

> +	}
> +
> +	igt_waitchildren();
> +
> +	igt_fork(child, 1) {
> +		write_u64_file("/proc/sys/dev/i915/perf_stream_paranoid", 0);
> +
> +		igt_drop_root();
> +
> +		igt_assert(has_i915_perf_disable_preemption_support(drm_fd));
> +	}
> +
> +	igt_waitchildren();

I think this could be split into two sub-tests. Do you plan to add more 
API tests?

Thanks,
Antonio

> +}
> +