From 56463b78cdca8e9ff8cc1759bca0c0777a061d6b Mon Sep 17 00:00:00 2001 From: Venkatesh Pallipadi Date: Mon, 5 Feb 2007 16:12:45 -0800 Subject: [PATCH] [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 Cc: Gautham R Shenoy Signed-off-by: Andrew Morton Signed-off-by: Dave Jones --- drivers/cpufreq/cpufreq_ondemand.c | 34 ++++++++++++++---------------- 1 file changed, 16 insertions(+), 18 deletions(-) diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index a480834c9627..bcf8bb877a8b 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); + -- 2.39.5