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[CPUFREQ] ondemand governor use new cpufreq rwsem locking in work callback

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Eliminate flush_workqueue in cpufreq_governor(STOP) callpath. Using flush
there has a deadlock potential as in

http://uwsg.iu.edu/hypermail/linux/kernel/0611.3/1223.html

Also, cleanup the locking issues with do_dbs_timer delayed_work callback.  As
it changes the CPU frequency using __cpufreq_target, it needs to have
policy_rwsem in write mode, which also protects it from hot plug.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Venkatesh Pallipadi 2007-02-05 16:12:45 -08:00 committed by Dave Jones
parent 529af7a14f
commit 56463b78cd
1 changed files with 16 additions and 18 deletions
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34
drivers/cpufreq/cpufreq_ondemand.c
View file

@ -437,8 +437,14 @@ static void do_dbs_timer(struct work_struct *work)
delay -= jiffies % delay;
if (!dbs_info->enable)
if (lock_policy_rwsem_write(cpu) < 0)
return;
if (!dbs_info->enable) {
unlock_policy_rwsem_write(cpu);
return;
}
/* Common NORMAL_SAMPLE setup */
dbs_info->sample_type = DBS_NORMAL_SAMPLE;
if (!dbs_tuners_ins.powersave_bias ||
@ -455,6 +461,7 @@ static void do_dbs_timer(struct work_struct *work)
CPUFREQ_RELATION_H);
}
queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
unlock_policy_rwsem_write(cpu);
}
static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
@ -463,6 +470,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
delay -= jiffies % delay;
dbs_info->enable = 1;
ondemand_powersave_bias_init();
dbs_info->sample_type = DBS_NORMAL_SAMPLE;
INIT_DELAYED_WORK_NAR(&dbs_info->work, do_dbs_timer);
@ -474,7 +482,6 @@ static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
{
dbs_info->enable = 0;
cancel_delayed_work(&dbs_info->work);
flush_workqueue(kondemand_wq);
}
static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
@ -503,21 +510,9 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
mutex_lock(&dbs_mutex);
dbs_enable++;
if (dbs_enable == 1) {
kondemand_wq = create_workqueue("kondemand");
if (!kondemand_wq) {
printk(KERN_ERR
"Creation of kondemand failed\n");
dbs_enable--;
mutex_unlock(&dbs_mutex);
return -ENOSPC;
}
}
rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
if (rc) {
if (dbs_enable == 1)
destroy_workqueue(kondemand_wq);
dbs_enable--;
mutex_unlock(&dbs_mutex);
return rc;
@ -532,7 +527,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
j_dbs_info->prev_cpu_wall = get_jiffies_64();
}
this_dbs_info->cpu = cpu;
this_dbs_info->enable = 1;
/*
* Start the timerschedule work, when this governor
* is used for first time
@ -562,9 +556,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
dbs_timer_exit(this_dbs_info);
sysfs_remove_group(&policy->kobj, &dbs_attr_group);
dbs_enable--;
if (dbs_enable == 0)
destroy_workqueue(kondemand_wq);
mutex_unlock(&dbs_mutex);
break;
@ -593,12 +584,18 @@ static struct cpufreq_governor cpufreq_gov_dbs = {
static int __init cpufreq_gov_dbs_init(void)
{
kondemand_wq = create_workqueue("kondemand");
if (!kondemand_wq) {
printk(KERN_ERR "Creation of kondemand failed\n");
return -EFAULT;
}
return cpufreq_register_governor(&cpufreq_gov_dbs);
}
static void __exit cpufreq_gov_dbs_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_dbs);
destroy_workqueue(kondemand_wq);
}
@ -610,3 +607,4 @@ MODULE_LICENSE("GPL");
module_init(cpufreq_gov_dbs_init);
module_exit(cpufreq_gov_dbs_exit);