diff options
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r-- | drivers/cpufreq/cpufreq.c | 110 |
1 files changed, 31 insertions, 79 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 87ed83a..6c9cbb9 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -53,47 +53,6 @@ static inline bool has_target(void) } /* - * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure - * all cpufreq/hotplug/workqueue/etc related lock issues. - * - * The rules for this semaphore: - * - Any routine that wants to read from the policy structure will - * do a down_read on this semaphore. - * - Any routine that will write to the policy structure and/or may take away - * the policy altogether (eg. CPU hotplug), will hold this lock in write - * mode before doing so. - * - * Additional rules: - * - Governor routines that can be called in cpufreq hotplug path should not - * take this sem as top level hotplug notifier handler takes this. - * - Lock should not be held across - * __cpufreq_governor(data, CPUFREQ_GOV_STOP); - */ -static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem); - -#define lock_policy_rwsem(mode, cpu) \ -static void lock_policy_rwsem_##mode(int cpu) \ -{ \ - struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu); \ - BUG_ON(!policy); \ - down_##mode(&per_cpu(cpu_policy_rwsem, policy->cpu)); \ -} - -lock_policy_rwsem(read, cpu); -lock_policy_rwsem(write, cpu); - -#define unlock_policy_rwsem(mode, cpu) \ -static void unlock_policy_rwsem_##mode(int cpu) \ -{ \ - struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu); \ - BUG_ON(!policy); \ - up_##mode(&per_cpu(cpu_policy_rwsem, policy->cpu)); \ -} - -unlock_policy_rwsem(read, cpu); -unlock_policy_rwsem(write, cpu); - -/* * rwsem to guarantee that cpufreq driver module doesn't unload during critical * sections */ @@ -688,14 +647,14 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf) if (!down_read_trylock(&cpufreq_rwsem)) return -EINVAL; - lock_policy_rwsem_read(policy->cpu); + down_read(&policy->rwsem); if (fattr->show) ret = fattr->show(policy, buf); else ret = -EIO; - unlock_policy_rwsem_read(policy->cpu); + up_read(&policy->rwsem); up_read(&cpufreq_rwsem); return ret; @@ -716,14 +675,14 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, if (!down_read_trylock(&cpufreq_rwsem)) goto unlock; - lock_policy_rwsem_write(policy->cpu); + down_write(&policy->rwsem); if (fattr->store) ret = fattr->store(policy, buf, count); else ret = -EIO; - unlock_policy_rwsem_write(policy->cpu); + up_write(&policy->rwsem); up_read(&cpufreq_rwsem); unlock: @@ -900,7 +859,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, } } - lock_policy_rwsem_write(policy->cpu); + down_write(&policy->rwsem); write_lock_irqsave(&cpufreq_driver_lock, flags); @@ -908,7 +867,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, per_cpu(cpufreq_cpu_data, cpu) = policy; write_unlock_irqrestore(&cpufreq_driver_lock, flags); - unlock_policy_rwsem_write(policy->cpu); + up_write(&policy->rwsem); if (has_target()) { if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) || @@ -955,6 +914,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void) goto err_free_cpumask; INIT_LIST_HEAD(&policy->policy_list); + init_rwsem(&policy->rwsem); + return policy; err_free_cpumask: @@ -977,19 +938,12 @@ static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu) if (WARN_ON(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)); + down_write(&policy->rwsem); policy->last_cpu = policy->cpu; policy->cpu = cpu; - up_write(&per_cpu(cpu_policy_rwsem, policy->last_cpu)); + up_write(&policy->rwsem); cpufreq_frequency_table_update_policy_cpu(policy); blocking_notifier_call_chain(&cpufreq_policy_notifier_list, @@ -1181,9 +1135,9 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy, if (ret) { pr_err("%s: Failed to move kobj: %d", __func__, ret); - lock_policy_rwsem_write(old_cpu); + down_write(&policy->rwsem); cpumask_set_cpu(old_cpu, policy->cpus); - unlock_policy_rwsem_write(old_cpu); + up_write(&policy->rwsem); ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj, "cpufreq"); @@ -1234,9 +1188,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, policy->governor->name, CPUFREQ_NAME_LEN); #endif - lock_policy_rwsem_read(cpu); + down_read(&policy->rwsem); cpus = cpumask_weight(policy->cpus); - unlock_policy_rwsem_read(cpu); + up_read(&policy->rwsem); if (cpu != policy->cpu) { if (!frozen) @@ -1276,12 +1230,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev, return -EINVAL; } - lock_policy_rwsem_write(cpu); + down_write(&policy->rwsem); cpus = cpumask_weight(policy->cpus); if (cpus > 1) cpumask_clear_cpu(cpu, policy->cpus); - unlock_policy_rwsem_write(cpu); + up_write(&policy->rwsem); /* If cpu is last user of policy, free policy */ if (cpus == 1) { @@ -1296,10 +1250,10 @@ static int __cpufreq_remove_dev_finish(struct device *dev, } if (!frozen) { - lock_policy_rwsem_read(cpu); + down_read(&policy->rwsem); kobj = &policy->kobj; cmp = &policy->kobj_unregister; - unlock_policy_rwsem_read(cpu); + up_read(&policy->rwsem); kobject_put(kobj); /* @@ -1479,19 +1433,22 @@ static unsigned int __cpufreq_get(unsigned int cpu) */ unsigned int cpufreq_get(unsigned int cpu) { + struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu); unsigned int ret_freq = 0; if (cpufreq_disabled() || !cpufreq_driver) return -ENOENT; + BUG_ON(!policy); + if (!down_read_trylock(&cpufreq_rwsem)) return 0; - lock_policy_rwsem_read(cpu); + down_read(&policy->rwsem); ret_freq = __cpufreq_get(cpu); - unlock_policy_rwsem_read(cpu); + up_read(&policy->rwsem); up_read(&cpufreq_rwsem); return ret_freq; @@ -1744,11 +1701,11 @@ int cpufreq_driver_target(struct cpufreq_policy *policy, { int ret = -EINVAL; - lock_policy_rwsem_write(policy->cpu); + down_write(&policy->rwsem); ret = __cpufreq_driver_target(policy, target_freq, relation); - unlock_policy_rwsem_write(policy->cpu); + up_write(&policy->rwsem); return ret; } @@ -1979,10 +1936,10 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, /* end old governor */ if (policy->governor) { __cpufreq_governor(policy, CPUFREQ_GOV_STOP); - unlock_policy_rwsem_write(new_policy->cpu); + up_write(&policy->rwsem); __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); - lock_policy_rwsem_write(new_policy->cpu); + down_write(&policy->rwsem); } /* start new governor */ @@ -1991,10 +1948,10 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, if (!__cpufreq_governor(policy, CPUFREQ_GOV_START)) { failed = 0; } else { - unlock_policy_rwsem_write(new_policy->cpu); + up_write(&policy->rwsem); __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); - lock_policy_rwsem_write(new_policy->cpu); + down_write(&policy->rwsem); } } @@ -2040,7 +1997,7 @@ int cpufreq_update_policy(unsigned int cpu) goto no_policy; } - lock_policy_rwsem_write(cpu); + down_write(&policy->rwsem); pr_debug("updating policy for CPU %u\n", cpu); memcpy(&new_policy, policy, sizeof(*policy)); @@ -2067,7 +2024,7 @@ int cpufreq_update_policy(unsigned int cpu) ret = cpufreq_set_policy(policy, &new_policy); - unlock_policy_rwsem_write(cpu); + up_write(&policy->rwsem); cpufreq_cpu_put(policy); no_policy: @@ -2225,14 +2182,9 @@ EXPORT_SYMBOL_GPL(cpufreq_unregister_driver); static int __init cpufreq_core_init(void) { - int cpu; - if (cpufreq_disabled()) return -ENODEV; - for_each_possible_cpu(cpu) - init_rwsem(&per_cpu(cpu_policy_rwsem, cpu)); - cpufreq_global_kobject = kobject_create(); BUG_ON(!cpufreq_global_kobject); register_syscore_ops(&cpufreq_syscore_ops); |