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SubjectRe: [Patch v4 3/6] cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support
On 27-07-21, 11:25, Thara Gopinath wrote:
> +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
> +{

> + /* In the unlikely case cpufreq is de-registered do not enable polling or h/w interrupt */
> +
> + spin_lock(&data->throttle_lock);
> + if (data->cancel_throttle) {
> + spin_unlock(&data->throttle_lock);
> + return;
> + }
> + spin_unlock(&data->throttle_lock);
> +
> + /*
> + * If h/w throttled frequency is higher than what cpufreq has requested for, stop
> + * polling and switch back to interrupt mechanism
> + */
> +
> + if (throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(policy->cpus)))
> + /* Clear the existing interrupts and enable it back */
> + enable_irq(data->throttle_irq);
> + else
> + mod_delayed_work(system_highpri_wq, &data->throttle_work,
> + msecs_to_jiffies(10));
> +}

> +static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
> +{
> + if (data->throttle_irq <= 0)
> + return;
> +
> + spin_lock(&data->throttle_lock);
> + data->cancel_throttle = true;
> + spin_unlock(&data->throttle_lock);
> + cancel_delayed_work_sync(&data->throttle_work);
> + free_irq(data->throttle_irq, data);
> +}

Lets see if we can still make it break :)

CPU0 CPU1

qcom_lmh_dcvs_notify() qcom_cpufreq_hw_lmh_exit()

spin_unlock()
spin_lock(),
cancel_throttle = true
spin_unlock()

cancel_delayed_work_sync()
mod_delayed_work()
free_irq()
kfree(data)
qcom_lmh_dcvs_poll()
Uses data.


Sorry, locking is fun :)

--
viresh

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