On Monday, June 24, 2013 06:38:17 PM Viresh Kumar wrote:
> On 24 June 2013 17:13, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> > On Wednesday, June 19, 2013 02:23:07 PM Viresh Kumar wrote:
> >> case CPUFREQ_POSTCHANGE:
> >> + WARN_ON(!transition_ongoing--);
> >
> > Shouldn't we try to avoid going into the negative range here?
>
> What about this patch? Find it attached to apply.
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 2d53f47..6624694 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -107,6 +107,9 @@ static void handle_update(struct work_struct *work);
> static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
> static struct srcu_notifier_head cpufreq_transition_notifier_list;
>
> +/* Tracks status of transition */
> +static int transition_ongoing;
> +
> static bool init_cpufreq_transition_notifier_list_called;
> static int __init init_cpufreq_transition_notifier_list(void)
> {
> @@ -264,6 +267,13 @@ void __cpufreq_notify_transition(struct
> cpufreq_policy *policy,
> switch (state) {
>
> case CPUFREQ_PRECHANGE:
> + if (transition_ongoing) {
> + WARN(1, "In middle of another frequency transition\n");
> + return;
> + }
You can do
if (WARN(transition_ongoing, "<text>"))
return;
and below analogously.
> +
> + transition_ongoing++;
> +
> /* detect if the driver reported a value as "old frequency"
> * which is not equal to what the cpufreq core thinks is
> * "old frequency".
> @@ -283,6 +293,13 @@ void __cpufreq_notify_transition(struct
> cpufreq_policy *policy,
> break;
>
> case CPUFREQ_POSTCHANGE:
> + if (!transition_ongoing) {
> + WARN(1, "No frequency transition in progress\n");
> + return;
> + }
> +
> + transition_ongoing--;
> +
> adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
> pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new,
> (unsigned long)freqs->cpu);
> @@ -1458,6 +1475,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
>
> if (cpufreq_disabled())
> return -ENODEV;
> + if (transition_ongoing)
> + return -EBUSY;
>
> /* Make sure that target_freq is within supported range */
> if (target_freq > policy->max)
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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