Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

[cascardo/linux.git] / drivers / cpufreq / cpufreq.c

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 43c24aa..04548f7 100644 (file)
--- 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);