On Tuesday, July 02, 2013 04:36:28 PM Viresh Kumar wrote:
> Commit 7c30ed ("cpufreq: make sure frequency transitions are serialized")
> interacts poorly with systems that have a single core freqency for all
> cores. On such systems we have a single policy for all cores with
> several CPUs. When we do a frequency transition the governor calls the
> pre and post change notifiers which causes cpufreq_notify_transition()
> per CPU. Since the policy is the same for all of them all CPUs after
> the first and the warnings added are generated by checking a per-policy
> flag the warnings will be triggered for all cores after the first.
>
> Fix this by allowing notifier to be called for n times. Where n is the number of
> cpus in policy->cpus.
>
> Reported-and-Tested-by: Mark Brown <broonie@xxxxxxxxxx>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> Hi Rafael,
>
> This is a fix for 3.11.
Queued up for 3.11.
Thanks,
Rafael
> drivers/cpufreq/cpufreq.c | 7 ++++---
> include/linux/cpufreq.h | 2 +-
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index b557503..b7bda8d 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -312,11 +312,12 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
> switch (state) {
>
> case CPUFREQ_PRECHANGE:
> - if (WARN(policy->transition_ongoing,
> + if (WARN(policy->transition_ongoing ==
> + cpumask_weight(policy->cpus),
> "In middle of another frequency transition\n"))
> return;
>
> - policy->transition_ongoing = true;
> + policy->transition_ongoing++;
>
> /* detect if the driver reported a value as "old frequency"
> * which is not equal to what the cpufreq core thinks is
> @@ -341,7 +342,7 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
> "No frequency transition in progress\n"))
> return;
>
> - policy->transition_ongoing = false;
> + policy->transition_ongoing--;
>
> adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
> pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new,
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 4d7390b..90d5a15 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -119,7 +119,7 @@ struct cpufreq_policy {
>
> struct kobject kobj;
> struct completion kobj_unregister;
> - bool transition_ongoing; /* Tracks transition status */
> + int transition_ongoing; /* Tracks transition status */
> };
>
> #define CPUFREQ_ADJUST (0)
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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