The patch titled
ondemand governor use new cpufreq rwsem locking in work callback
has been removed from the -mm tree. Its filename was
ondemand-governor-use-new-cpufreq-rwsem-locking-in-work-callback.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: ondemand governor use new cpufreq rwsem locking in work callback
From: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Gautham R Shenoy <ego@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/cpufreq_ondemand.c | 34 ++++++++++++---------------
1 file changed, 16 insertions(+), 18 deletions(-)
diff -puN drivers/cpufreq/cpufreq_ondemand.c~ondemand-governor-use-new-cpufreq-rwsem-locking-in-work-callback drivers/cpufreq/cpufreq_ondemand.c
--- a/drivers/cpufreq/cpufreq_ondemand.c~ondemand-governor-use-new-cpufreq-rwsem-locking-in-work-callback
+++ a/drivers/cpufreq/cpufreq_ondemand.c
@@ -437,8 +437,14 @@ static void do_dbs_timer(struct work_str
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_str
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
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
{
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 c
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 c
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 c
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_g
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);
+
_
Patches currently in -mm which might be from venkatesh.pallipadi@xxxxxxxxx are
git-cpufreq.patch
workqueue-fix-freezeable-workqueues-implementation.patch
workqueue-fix-flush_workqueue-vs-cpu_dead-race.patch
workqueue-dont-clear-cwq-thread-until-it-exits.patch
workqueue-dont-migrate-pending-works-from-the-dead-cpu.patch
-
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