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Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
-rw-r--r--drivers/cpufreq/cpufreq.c34
1 files changed, 23 insertions, 11 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 43c24aa756f6..04548f7023af 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -952,9 +952,20 @@ static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
if (cpu == policy->cpu)
return;
+ /*
+ * Take direct locks as lock_policy_rwsem_write wouldn't work here.
+ * Also lock for last cpu is enough here as contention will happen only
+ * after policy->cpu is changed and after it is changed, other threads
+ * will try to acquire lock for new cpu. And policy is already updated
+ * by then.
+ */
+ down_write(&per_cpu(cpu_policy_rwsem, policy->cpu));
+
policy->last_cpu = policy->cpu;
policy->cpu = cpu;
+ up_write(&per_cpu(cpu_policy_rwsem, policy->last_cpu));
+
#ifdef CONFIG_CPU_FREQ_TABLE
cpufreq_frequency_table_update_policy_cpu(policy);
#endif
@@ -1125,7 +1136,7 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy,
int ret;
/* first sibling now owns the new sysfs dir */
- cpu_dev = get_cpu_device(cpumask_first(policy->cpus));
+ cpu_dev = get_cpu_device(cpumask_any_but(policy->cpus, old_cpu));
/* Don't touch sysfs files during light-weight tear-down */
if (frozen)
@@ -1189,12 +1200,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
policy->governor->name, CPUFREQ_NAME_LEN);
#endif
- WARN_ON(lock_policy_rwsem_write(cpu));
+ lock_policy_rwsem_read(cpu);
cpus = cpumask_weight(policy->cpus);
-
- if (cpus > 1)
- cpumask_clear_cpu(cpu, policy->cpus);
- unlock_policy_rwsem_write(cpu);
+ unlock_policy_rwsem_read(cpu);
if (cpu != policy->cpu) {
if (!frozen)
@@ -1203,9 +1211,7 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
new_cpu = cpufreq_nominate_new_policy_cpu(policy, cpu, frozen);
if (new_cpu >= 0) {
- WARN_ON(lock_policy_rwsem_write(cpu));
update_policy_cpu(policy, new_cpu);
- unlock_policy_rwsem_write(cpu);
if (!frozen) {
pr_debug("%s: policy Kobject moved to cpu: %d "
@@ -1237,9 +1243,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
return -EINVAL;
}
- lock_policy_rwsem_read(cpu);
+ WARN_ON(lock_policy_rwsem_write(cpu));
cpus = cpumask_weight(policy->cpus);
- unlock_policy_rwsem_read(cpu);
+
+ if (cpus > 1)
+ cpumask_clear_cpu(cpu, policy->cpus);
+ unlock_policy_rwsem_write(cpu);
/* If cpu is last user of policy, free policy */
if (cpus == 1) {
@@ -1451,6 +1460,9 @@ unsigned int cpufreq_get(unsigned int cpu)
{
unsigned int ret_freq = 0;
+ if (cpufreq_disabled() || !cpufreq_driver)
+ return -ENOENT;
+
if (!down_read_trylock(&cpufreq_rwsem))
return 0;
@@ -2095,7 +2107,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
write_lock_irqsave(&cpufreq_driver_lock, flags);
if (cpufreq_driver) {
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
- return -EBUSY;
+ return -EEXIST;
}
cpufreq_driver = driver_data;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);