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authorVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>2007-02-06 00:12:45 (GMT)
committerDave Jones <davej@redhat.com>2007-02-11 01:01:48 (GMT)
commit56463b78cdca8e9ff8cc1759bca0c0777a061d6b (patch)
tree435e98e919e96da931b1874eae6c888b734dea6d /drivers/cpufreq
parent529af7a14f04f92213bac371931a2b2b060c63fa (diff)
downloadlinux-56463b78cdca8e9ff8cc1759bca0c0777a061d6b.tar.xz
[CPUFREQ] ondemand governor use new cpufreq rwsem locking in work callback
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>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq_ondemand.c34
1 files changed, 16 insertions, 18 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index a480834..bcf8bb8 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -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);
+