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Commit 78e6913a authored by Dmitry Torokhov's avatar Dmitry Torokhov Committed by Amit Pundir
Browse files

cpufreq: interactive: fix policy locking 

cpufreq_interactive_speedchange_task() is running as a separate kernel
thread and is calling __cpufreq_driver_target(), which requires callers
to hold policy->rwsem for writing to prevent racing with other parts of
the kernel trying to adjust the frequency, for example kernel thermal
throttling. Let's change the code to take policy->rwsem and while at it
refactor the code a bit.

This was originally 2 changes reviewed at:
	https://chromium-review.googlesource.com/246273
	https://chromium-review.googlesource.com/256120



Change-Id: Icc2d97c6c1b929acd2ee32e8c81d81fd2af778ab
Signed-off-by: default avatarDmitry Torokhov <dtor@chromium.org>
Reviewed-by: default avatarDylan Reid <dgreid@chromium.org>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
Signed-off-by: default avatarDmitry Torokhov <dtor@google.com>
parent 12988635

drivers/cpufreq/cpufreq_interactive.c

+59 −38
Original line number Diff line number Diff line
@@ -489,6 +489,58 @@ static void cpufreq_interactive_idle_end(void) 
	up_read(&pcpu->enable_sem);

}



static void cpufreq_interactive_get_policy_info(struct cpufreq_policy *policy,

						unsigned int *pmax_freq,

						u64 *phvt, u64 *pfvt)

{

	struct cpufreq_interactive_cpuinfo *pcpu;

	unsigned int max_freq = 0;

	u64 hvt = ~0ULL, fvt = 0;

	unsigned int i;



	for_each_cpu(i, policy->cpus) {

		pcpu = &per_cpu(cpuinfo, i);



		fvt = max(fvt, pcpu->loc_floor_val_time);

		if (pcpu->target_freq > max_freq) {

			max_freq = pcpu->target_freq;

			hvt = pcpu->loc_hispeed_val_time;

		} else if (pcpu->target_freq == max_freq) {

			hvt = min(hvt, pcpu->loc_hispeed_val_time);

		}

	}



	*pmax_freq = max_freq;

	*phvt = hvt;

	*pfvt = fvt;

}



static void cpufreq_interactive_adjust_cpu(unsigned int cpu,

					   struct cpufreq_policy *policy)

{

	struct cpufreq_interactive_cpuinfo *pcpu;

	u64 hvt, fvt;

	unsigned int max_freq;

	int i;



	cpufreq_interactive_get_policy_info(policy, &max_freq, &hvt, &fvt);



	for_each_cpu(i, policy->cpus) {

		pcpu = &per_cpu(cpuinfo, i);

		pcpu->pol_floor_val_time = fvt;

	}



	if (max_freq != policy->cur) {

		__cpufreq_driver_target(policy, max_freq, CPUFREQ_RELATION_H);

		for_each_cpu(i, policy->cpus) {

			pcpu = &per_cpu(cpuinfo, i);

			pcpu->pol_hispeed_val_time = hvt;

		}

	}



	trace_cpufreq_interactive_setspeed(cpu, max_freq, policy->cur);

}



static int cpufreq_interactive_speedchange_task(void *data)

{

	unsigned int cpu;
@@ -517,49 +569,18 @@ static int cpufreq_interactive_speedchange_task(void *data) 
		spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);



		for_each_cpu(cpu, &tmp_mask) {

			unsigned int j;

			unsigned int max_freq = 0;

			struct cpufreq_interactive_cpuinfo *pjcpu;

			u64 hvt = ~0ULL, fvt = 0;



			pcpu = &per_cpu(cpuinfo, cpu);

			if (!down_read_trylock(&pcpu->enable_sem))

				continue;

			if (!pcpu->governor_enabled) {

				up_read(&pcpu->enable_sem);

				continue;

			}



			for_each_cpu(j, pcpu->policy->cpus) {

				pjcpu = &per_cpu(cpuinfo, j);

			down_write(&pcpu->policy->rwsem);



				fvt = max(fvt, pjcpu->loc_floor_val_time);

				if (pjcpu->target_freq > max_freq) {

					max_freq = pjcpu->target_freq;

					hvt = pjcpu->loc_hispeed_val_time;

				} else if (pjcpu->target_freq == max_freq) {

					hvt = min(hvt, pjcpu->loc_hispeed_val_time);

				}

			}

			for_each_cpu(j, pcpu->policy->cpus) {

				pjcpu = &per_cpu(cpuinfo, j);

				pjcpu->pol_floor_val_time = fvt;

			}



			if (max_freq != pcpu->policy->cur) {

				__cpufreq_driver_target(pcpu->policy,

							max_freq,

							CPUFREQ_RELATION_H);

				for_each_cpu(j, pcpu->policy->cpus) {

					pjcpu = &per_cpu(cpuinfo, j);

					pjcpu->pol_hispeed_val_time = hvt;

				}

			if (likely(down_read_trylock(&pcpu->enable_sem))) {

				if (likely(pcpu->governor_enabled))

					cpufreq_interactive_adjust_cpu(cpu,

							pcpu->policy);

				up_read(&pcpu->enable_sem);

			}

			trace_cpufreq_interactive_setspeed(cpu,

						     pcpu->target_freq,

						     pcpu->policy->cur);



			up_read(&pcpu->enable_sem);

			up_write(&pcpu->policy->rwsem);

		}

	}