static int alpha_pmu_add()

in kernel/perf_event.c [433:477]

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

static int alpha_pmu_add(struct perf_event *event, int flags)
{
	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
	struct hw_perf_event *hwc = &event->hw;
	int n0;
	int ret;
	unsigned long irq_flags;

	/*
	 * The Sparc code has the IRQ disable first followed by the perf
	 * disable, however this can lead to an overflowed counter with the
	 * PMI disabled on rare occasions.  The alpha_perf_event_update()
	 * routine should detect this situation by noting a negative delta,
	 * nevertheless we disable the PMCs first to enable a potential
	 * final PMI to occur before we disable interrupts.
	 */
	perf_pmu_disable(event->pmu);
	local_irq_save(irq_flags);

	/* Default to error to be returned */
	ret = -EAGAIN;

	/* Insert event on to PMU and if successful modify ret to valid return */
	n0 = cpuc->n_events;
	if (n0 < alpha_pmu->num_pmcs) {
		cpuc->event[n0] = event;
		cpuc->evtype[n0] = event->hw.event_base;
		cpuc->current_idx[n0] = PMC_NO_INDEX;

		if (!alpha_check_constraints(cpuc->event, cpuc->evtype, n0+1)) {
			cpuc->n_events++;
			cpuc->n_added++;
			ret = 0;
		}
	}

	hwc->state = PERF_HES_UPTODATE;
	if (!(flags & PERF_EF_START))
		hwc->state |= PERF_HES_STOPPED;

	local_irq_restore(irq_flags);
	perf_pmu_enable(event->pmu);

	return ret;
}