Colin Cross <ccross@xxxxxxxxxxx> writes:
> +/**
> + * cpuidle_coupled_cpu_set_alive - adjust alive_count during hotplug transitions
> + * @cpu: target cpu number
> + * @alive: whether the target cpu is going up or down
> + *
> + * Run on the cpu that is bringing up the target cpu, before the target cpu
> + * has been booted, or after the target cpu is completely dead.
> + */
> +static void cpuidle_coupled_cpu_set_alive(int cpu, bool alive)
> +{
> + struct cpuidle_device *dev;
> + struct cpuidle_coupled *coupled;
> +
> + mutex_lock(&cpuidle_lock);
> +
> + dev = per_cpu(cpuidle_devices, cpu);
> + if (!dev->coupled)
> + goto out;
> +
> + coupled = dev->coupled;
> +
> + /*
> + * waiting_count must be at least 1 less than alive_count, because
> + * this cpu is not waiting. Spin until all cpus have noticed this cpu
> + * is not idle and exited the ready loop before changing alive_count.
> + */
> + while (atomic_read(&coupled->ready_count))
> + cpu_relax();
> +
> + smp_mb__before_atomic_inc();
> + atomic_inc(&coupled->alive_count);
This doesn't look quite right. alive_count is incrmented whether the
CPU is going up or down?
Maybe I misunderstood something, but I don't see anywhere where
alive_count is decrmemented after a CPU is removed.
Kevin
> + smp_mb__after_atomic_inc();
> +
> + if (alive)
> + coupled->requested_state[dev->cpu] = CPUIDLE_COUPLED_NOT_IDLE;
> + else
> + coupled->requested_state[dev->cpu] = CPUIDLE_COUPLED_DEAD;
> +
> +out:
> + mutex_unlock(&cpuidle_lock);
> +}
> +
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