Messages in this thread | | | Subject | Re: [Patch v4 3/6] cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support | From | Thara Gopinath <> | Date | Wed, 28 Jul 2021 18:19:05 -0400 |
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On 7/27/21 11:50 PM, Viresh Kumar wrote: > 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 :)
Ha! I was too lazy to write this down! So how about I make this a mutex and put mod_delayed_work() inside the lock. So it will be something like below
qcom_lmh_dcvs_notify() qcom_cpufreq_hw_lmh_exit()
mutex_lock() mutex_lock() if (data->cancel_throttle) { cancel_throttle = true mutex_unlock() mutex_unlock() return cancel_delayed_work_sync() } free_irq() enable_irq() / mod_delayed_work() mutex_unlock()
I will let you break it!
>
-- Warm Regards Thara (She/Her/Hers)
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