int csky_pmu_event_set_period()

in kernel/perf_event.c [878:917]

• 28 lines of code
• 5 McCabe index (conditional complexity)

int  csky_pmu_event_set_period(struct perf_event *event)
{
	struct hw_perf_event *hwc = &event->hw;
	s64 left = local64_read(&hwc->period_left);
	s64 period = hwc->sample_period;
	int ret = 0;

	if (unlikely(left <= -period)) {
		left = period;
		local64_set(&hwc->period_left, left);
		hwc->last_period = period;
		ret = 1;
	}

	if (unlikely(left <= 0)) {
		left += period;
		local64_set(&hwc->period_left, left);
		hwc->last_period = period;
		ret = 1;
	}

	if (left > (s64)csky_pmu.max_period)
		left = csky_pmu.max_period;

	/*
	 * The hw event starts counting from this event offset,
	 * mark it to be able to extract future "deltas":
	 */
	local64_set(&hwc->prev_count, (u64)(-left));

	if (hw_raw_write_mapping[hwc->idx] != NULL)
		hw_raw_write_mapping[hwc->idx]((u64)(-left) &
						csky_pmu.max_period);

	cpwcr(HPOFSR, ~BIT(hwc->idx) & cprcr(HPOFSR));

	perf_event_update_userpage(event);

	return ret;
}