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Commit 2cd7cbdf authored by Linus Torvalds's avatar Linus Torvalds
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[cpufreq] ondemand: make shutdown sequence more robust 



Shutting down the ondemand policy was fraught with potential
problems, causing issues for SMP suspend (which wants to hot-
unplug) all but the last CPU.

This should fix at least the worst problems (divide-by-zero
and infinite wait for the workqueue to shut down).

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 12157a8d

drivers/cpufreq/cpufreq_ondemand.c

+10 −6
Original line number Original line Diff line number Diff line
@@ -239,6 +239,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) 
	total_ticks = (unsigned int) cputime64_sub(cur_jiffies,

	total_ticks = (unsigned int) cputime64_sub(cur_jiffies,

			this_dbs_info->prev_cpu_wall);

			this_dbs_info->prev_cpu_wall);

	this_dbs_info->prev_cpu_wall = cur_jiffies;

	this_dbs_info->prev_cpu_wall = cur_jiffies;

	if (!total_ticks)

		return;

	/*

	/*

	 * Every sampling_rate, we check, if current idle time is less

	 * Every sampling_rate, we check, if current idle time is less

	 * than 20% (default), then we try to increase frequency

	 * than 20% (default), then we try to increase frequency
@@ -304,6 +306,9 @@ static void do_dbs_timer(void *data) 
	unsigned int cpu = smp_processor_id();

	unsigned int cpu = smp_processor_id();

	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);

	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);





	if (!dbs_info->enable)

		return;



	dbs_check_cpu(dbs_info);

	dbs_check_cpu(dbs_info);

	queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,

	queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,

			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));

			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
@@ -319,11 +324,11 @@ static inline void dbs_timer_init(unsigned int cpu) 
	return;

	return;

}

}





static inline void dbs_timer_exit(unsigned int cpu)

static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)

{

{

	struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);

	dbs_info->enable = 0;



	cancel_delayed_work(&dbs_info->work);

	cancel_rearming_delayed_workqueue(kondemand_wq, &dbs_info->work);

	flush_workqueue(kondemand_wq);

}

}





static int cpufreq_governor_dbs(struct cpufreq_policy *policy,

static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
@@ -396,8 +401,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 




	case CPUFREQ_GOV_STOP:

	case CPUFREQ_GOV_STOP:

		mutex_lock(&dbs_mutex);

		mutex_lock(&dbs_mutex);

		dbs_timer_exit(policy->cpu);

		dbs_timer_exit(this_dbs_info);

		this_dbs_info->enable = 0;

		sysfs_remove_group(&policy->kobj, &dbs_attr_group);

		sysfs_remove_group(&policy->kobj, &dbs_attr_group);

		dbs_enable--;

		dbs_enable--;

		if (dbs_enable == 0)

		if (dbs_enable == 0)