cpufreq: Fix serialization of frequency transitions (266c13d7) · Commits · 戴 / test

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@linaro.org> Signed-off-by:

Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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,

include/linux/cpufreq.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

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