[CPUFREQ] Rewrite lock in cpufreq to eliminate cpufreq/hotplug related issues
Yet another attempt to resolve cpufreq and hotplug locking issues. Patchset has 3 patches: * Rewrite the lock infrastructure of cpufreq using a per cpu rwsem. * Minor restructuring of work callback in ondemand driver. * Use the new cpufreq rwsem infrastructure in ondemand work. This patch: Convert policy->lock to rwsem and move it to per_cpu area. This rwsem will protect against both changing/accessing policy related parameters and CPU hot plug/unplug. [malattia@linux.it: fix oops in kref_put()] Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Mattia Dongili <malattia@linux.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Venkatesh Pallipadi
Dave Jones
Родитель
c120069779
Коммит
5a01f2e8f3
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@ -41,8 +41,67 @@ static struct cpufreq_driver *cpufreq_driver;
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static struct cpufreq_policy *cpufreq_cpu_data[NR_CPUS];
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static DEFINE_SPINLOCK(cpufreq_driver_lock);
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/*
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* cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
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* all cpufreq/hotplug/workqueue/etc related lock issues.
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*
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* The rules for this semaphore:
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* - Any routine that wants to read from the policy structure will
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* do a down_read on this semaphore.
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* - Any routine that will write to the policy structure and/or may take away
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* the policy altogether (eg. CPU hotplug), will hold this lock in write
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* mode before doing so.
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*
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* Additional rules:
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* - All holders of the lock should check to make sure that the CPU they
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* are concerned with are online after they get the lock.
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* - Governor routines that can be called in cpufreq hotplug path should not
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* take this sem as top level hotplug notifier handler takes this.
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*/
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static DEFINE_PER_CPU(int, policy_cpu);
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static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
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#define lock_policy_rwsem(mode, cpu) \
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int lock_policy_rwsem_##mode \
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(int cpu) \
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{ \
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int policy_cpu = per_cpu(policy_cpu, cpu); \
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BUG_ON(policy_cpu == -1); \
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down_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu)); \
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if (unlikely(!cpu_online(cpu))) { \
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up_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu)); \
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return -1; \
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} \
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\
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return 0; \
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}
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lock_policy_rwsem(read, cpu);
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EXPORT_SYMBOL_GPL(lock_policy_rwsem_read);
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lock_policy_rwsem(write, cpu);
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EXPORT_SYMBOL_GPL(lock_policy_rwsem_write);
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void unlock_policy_rwsem_read(int cpu)
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{
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int policy_cpu = per_cpu(policy_cpu, cpu);
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BUG_ON(policy_cpu == -1);
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up_read(&per_cpu(cpu_policy_rwsem, policy_cpu));
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}
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EXPORT_SYMBOL_GPL(unlock_policy_rwsem_read);
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void unlock_policy_rwsem_write(int cpu)
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{
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int policy_cpu = per_cpu(policy_cpu, cpu);
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BUG_ON(policy_cpu == -1);
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up_write(&per_cpu(cpu_policy_rwsem, policy_cpu));
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}
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EXPORT_SYMBOL_GPL(unlock_policy_rwsem_write);
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/* internal prototypes */
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static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
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static unsigned int __cpufreq_get(unsigned int cpu);
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static void handle_update(struct work_struct *work);
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/**
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@ -415,10 +474,8 @@ static ssize_t store_##file_name \
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if (ret != 1) \
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return -EINVAL; \
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\
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mutex_lock(&policy->lock); \
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ret = __cpufreq_set_policy(policy, &new_policy); \
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policy->user_policy.object = policy->object; \
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mutex_unlock(&policy->lock); \
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\
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return ret ? ret : count; \
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}
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@ -432,7 +489,7 @@ store_one(scaling_max_freq,max);
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static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy,
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char *buf)
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{
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unsigned int cur_freq = cpufreq_get(policy->cpu);
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unsigned int cur_freq = __cpufreq_get(policy->cpu);
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if (!cur_freq)
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return sprintf(buf, "<unknown>");
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return sprintf(buf, "%u\n", cur_freq);
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@ -479,12 +536,10 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
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/* Do not use cpufreq_set_policy here or the user_policy.max
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will be wrongly overridden */
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mutex_lock(&policy->lock);
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ret = __cpufreq_set_policy(policy, &new_policy);
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policy->user_policy.policy = policy->policy;
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policy->user_policy.governor = policy->governor;
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mutex_unlock(&policy->lock);
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if (ret)
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return ret;
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@ -589,11 +644,17 @@ static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf)
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policy = cpufreq_cpu_get(policy->cpu);
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if (!policy)
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return -EINVAL;
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if (lock_policy_rwsem_read(policy->cpu) < 0)
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return -EINVAL;
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if (fattr->show)
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ret = fattr->show(policy, buf);
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else
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ret = -EIO;
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unlock_policy_rwsem_read(policy->cpu);
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cpufreq_cpu_put(policy);
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return ret;
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}
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@ -607,11 +668,17 @@ static ssize_t store(struct kobject * kobj, struct attribute * attr,
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policy = cpufreq_cpu_get(policy->cpu);
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if (!policy)
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return -EINVAL;
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if (lock_policy_rwsem_write(policy->cpu) < 0)
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return -EINVAL;
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if (fattr->store)
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ret = fattr->store(policy, buf, count);
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else
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ret = -EIO;
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unlock_policy_rwsem_write(policy->cpu);
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cpufreq_cpu_put(policy);
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return ret;
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}
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@ -685,8 +752,10 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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policy->cpu = cpu;
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policy->cpus = cpumask_of_cpu(cpu);
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mutex_init(&policy->lock);
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mutex_lock(&policy->lock);
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/* Initially set CPU itself as the policy_cpu */
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per_cpu(policy_cpu, cpu) = cpu;
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lock_policy_rwsem_write(cpu);
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init_completion(&policy->kobj_unregister);
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INIT_WORK(&policy->update, handle_update);
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@ -696,7 +765,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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ret = cpufreq_driver->init(policy);
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if (ret) {
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dprintk("initialization failed\n");
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(cpu);
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goto err_out;
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}
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@ -710,6 +779,14 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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*/
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managed_policy = cpufreq_cpu_get(j);
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if (unlikely(managed_policy)) {
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/* Set proper policy_cpu */
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unlock_policy_rwsem_write(cpu);
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per_cpu(policy_cpu, cpu) = managed_policy->cpu;
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if (lock_policy_rwsem_write(cpu) < 0)
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goto err_out_driver_exit;
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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managed_policy->cpus = policy->cpus;
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cpufreq_cpu_data[cpu] = managed_policy;
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@ -720,13 +797,13 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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&managed_policy->kobj,
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"cpufreq");
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if (ret) {
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(cpu);
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goto err_out_driver_exit;
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}
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cpufreq_debug_enable_ratelimit();
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mutex_unlock(&policy->lock);
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ret = 0;
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unlock_policy_rwsem_write(cpu);
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goto err_out_driver_exit; /* call driver->exit() */
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}
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}
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@ -740,7 +817,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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ret = kobject_register(&policy->kobj);
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if (ret) {
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(cpu);
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goto err_out_driver_exit;
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}
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/* set up files for this cpu device */
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@ -755,8 +832,10 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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for_each_cpu_mask(j, policy->cpus)
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for_each_cpu_mask(j, policy->cpus) {
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cpufreq_cpu_data[j] = policy;
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per_cpu(policy_cpu, j) = policy->cpu;
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}
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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/* symlink affected CPUs */
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@ -772,14 +851,14 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
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ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
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"cpufreq");
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if (ret) {
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(cpu);
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goto err_out_unregister;
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}
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}
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policy->governor = NULL; /* to assure that the starting sequence is
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* run in cpufreq_set_policy */
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(cpu);
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/* set default policy */
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ret = cpufreq_set_policy(&new_policy);
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@ -820,11 +899,13 @@ module_out:
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/**
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* cpufreq_remove_dev - remove a CPU device
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* __cpufreq_remove_dev - remove a CPU device
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*
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* Removes the cpufreq interface for a CPU device.
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* Caller should already have policy_rwsem in write mode for this CPU.
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* This routine frees the rwsem before returning.
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*/
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static int cpufreq_remove_dev (struct sys_device * sys_dev)
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static int __cpufreq_remove_dev (struct sys_device * sys_dev)
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{
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unsigned int cpu = sys_dev->id;
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unsigned long flags;
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@ -843,6 +924,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
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if (!data) {
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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cpufreq_debug_enable_ratelimit();
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unlock_policy_rwsem_write(cpu);
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return -EINVAL;
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}
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cpufreq_cpu_data[cpu] = NULL;
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@ -859,6 +941,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
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sysfs_remove_link(&sys_dev->kobj, "cpufreq");
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cpufreq_cpu_put(data);
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cpufreq_debug_enable_ratelimit();
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unlock_policy_rwsem_write(cpu);
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return 0;
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}
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#endif
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@ -867,6 +950,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
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if (!kobject_get(&data->kobj)) {
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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cpufreq_debug_enable_ratelimit();
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unlock_policy_rwsem_write(cpu);
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return -EFAULT;
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}
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@ -900,10 +984,10 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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#endif
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mutex_lock(&data->lock);
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if (cpufreq_driver->target)
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__cpufreq_governor(data, CPUFREQ_GOV_STOP);
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mutex_unlock(&data->lock);
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unlock_policy_rwsem_write(cpu);
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kobject_unregister(&data->kobj);
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@ -927,6 +1011,18 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
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}
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static int cpufreq_remove_dev (struct sys_device * sys_dev)
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{
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unsigned int cpu = sys_dev->id;
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int retval;
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if (unlikely(lock_policy_rwsem_write(cpu)))
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BUG();
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retval = __cpufreq_remove_dev(sys_dev);
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return retval;
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}
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static void handle_update(struct work_struct *work)
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{
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struct cpufreq_policy *policy =
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@ -974,9 +1070,12 @@ unsigned int cpufreq_quick_get(unsigned int cpu)
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unsigned int ret_freq = 0;
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if (policy) {
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mutex_lock(&policy->lock);
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if (unlikely(lock_policy_rwsem_read(cpu)))
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return ret_freq;
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ret_freq = policy->cur;
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_read(cpu);
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cpufreq_cpu_put(policy);
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}
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@ -985,24 +1084,13 @@ unsigned int cpufreq_quick_get(unsigned int cpu)
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EXPORT_SYMBOL(cpufreq_quick_get);
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/**
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* cpufreq_get - get the current CPU frequency (in kHz)
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* @cpu: CPU number
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*
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* Get the CPU current (static) CPU frequency
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*/
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unsigned int cpufreq_get(unsigned int cpu)
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static unsigned int __cpufreq_get(unsigned int cpu)
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{
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struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
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struct cpufreq_policy *policy = cpufreq_cpu_data[cpu];
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unsigned int ret_freq = 0;
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if (!policy)
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return 0;
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if (!cpufreq_driver->get)
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goto out;
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mutex_lock(&policy->lock);
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return (ret_freq);
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ret_freq = cpufreq_driver->get(cpu);
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@ -1016,11 +1104,33 @@ unsigned int cpufreq_get(unsigned int cpu)
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}
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}
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mutex_unlock(&policy->lock);
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return (ret_freq);
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}
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out:
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/**
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* cpufreq_get - get the current CPU frequency (in kHz)
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* @cpu: CPU number
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*
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* Get the CPU current (static) CPU frequency
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*/
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unsigned int cpufreq_get(unsigned int cpu)
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{
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unsigned int ret_freq = 0;
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struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
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if (!policy)
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goto out;
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if (unlikely(lock_policy_rwsem_read(cpu)))
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goto out_policy;
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ret_freq = __cpufreq_get(cpu);
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unlock_policy_rwsem_read(cpu);
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out_policy:
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cpufreq_cpu_put(policy);
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out:
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return (ret_freq);
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}
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EXPORT_SYMBOL(cpufreq_get);
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@ -1297,18 +1407,19 @@ int cpufreq_driver_target(struct cpufreq_policy *policy,
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if (!policy)
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return -EINVAL;
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mutex_lock(&policy->lock);
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if (unlikely(lock_policy_rwsem_write(policy->cpu)))
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return -EINVAL;
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ret = __cpufreq_driver_target(policy, target_freq, relation);
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mutex_unlock(&policy->lock);
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unlock_policy_rwsem_write(policy->cpu);
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cpufreq_cpu_put(policy);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpufreq_driver_target);
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int cpufreq_driver_getavg(struct cpufreq_policy *policy)
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int __cpufreq_driver_getavg(struct cpufreq_policy *policy)
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{
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int ret = 0;
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@ -1316,17 +1427,13 @@ int cpufreq_driver_getavg(struct cpufreq_policy *policy)
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if (!policy)
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return -EINVAL;
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mutex_lock(&policy->lock);
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if (cpu_online(policy->cpu) && cpufreq_driver->getavg)
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ret = cpufreq_driver->getavg(policy->cpu);
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mutex_unlock(&policy->lock);
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cpufreq_cpu_put(policy);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpufreq_driver_getavg);
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EXPORT_SYMBOL_GPL(__cpufreq_driver_getavg);
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/*
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* when "event" is CPUFREQ_GOV_LIMITS
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@ -1410,9 +1517,7 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
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if (!cpu_policy)
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return -EINVAL;
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mutex_lock(&cpu_policy->lock);
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memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
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mutex_unlock(&cpu_policy->lock);
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cpufreq_cpu_put(cpu_policy);
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return 0;
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@ -1528,8 +1633,9 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
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if (!data)
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return -EINVAL;
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/* lock this CPU */
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mutex_lock(&data->lock);
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if (unlikely(lock_policy_rwsem_write(policy->cpu)))
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return -EINVAL;
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ret = __cpufreq_set_policy(data, policy);
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data->user_policy.min = data->min;
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@ -1537,7 +1643,7 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
|
|||
data->user_policy.policy = data->policy;
|
||||
data->user_policy.governor = data->governor;
|
||||
|
||||
mutex_unlock(&data->lock);
|
||||
unlock_policy_rwsem_write(policy->cpu);
|
||||
|
||||
cpufreq_cpu_put(data);
|
||||
|
||||
|
|
@ -1562,7 +1668,8 @@ int cpufreq_update_policy(unsigned int cpu)
|
|||
if (!data)
|
||||
return -ENODEV;
|
||||
|
||||
mutex_lock(&data->lock);
|
||||
if (unlikely(lock_policy_rwsem_write(cpu)))
|
||||
return -EINVAL;
|
||||
|
||||
dprintk("updating policy for CPU %u\n", cpu);
|
||||
memcpy(&policy, data, sizeof(struct cpufreq_policy));
|
||||
|
|
@ -1587,7 +1694,8 @@ int cpufreq_update_policy(unsigned int cpu)
|
|||
|
||||
ret = __cpufreq_set_policy(data, &policy);
|
||||
|
||||
mutex_unlock(&data->lock);
|
||||
unlock_policy_rwsem_write(cpu);
|
||||
|
||||
cpufreq_cpu_put(data);
|
||||
return ret;
|
||||
}
|
||||
|
|
@ -1597,31 +1705,28 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb,
|
|||
unsigned long action, void *hcpu)
|
||||
{
|
||||
unsigned int cpu = (unsigned long)hcpu;
|
||||
struct cpufreq_policy *policy;
|
||||
struct sys_device *sys_dev;
|
||||
struct cpufreq_policy *policy;
|
||||
|
||||
sys_dev = get_cpu_sysdev(cpu);
|
||||
|
||||
if (sys_dev) {
|
||||
switch (action) {
|
||||
case CPU_ONLINE:
|
||||
cpufreq_add_dev(sys_dev);
|
||||
break;
|
||||
case CPU_DOWN_PREPARE:
|
||||
/*
|
||||
* We attempt to put this cpu in lowest frequency
|
||||
* possible before going down. This will permit
|
||||
* hardware-managed P-State to switch other related
|
||||
* threads to min or higher speeds if possible.
|
||||
*/
|
||||
if (unlikely(lock_policy_rwsem_write(cpu)))
|
||||
BUG();
|
||||
|
||||
policy = cpufreq_cpu_data[cpu];
|
||||
if (policy) {
|
||||
cpufreq_driver_target(policy, policy->min,
|
||||
__cpufreq_driver_target(policy, policy->min,
|
||||
CPUFREQ_RELATION_H);
|
||||
}
|
||||
__cpufreq_remove_dev(sys_dev);
|
||||
break;
|
||||
case CPU_DEAD:
|
||||
cpufreq_remove_dev(sys_dev);
|
||||
case CPU_DOWN_FAILED:
|
||||
cpufreq_add_dev(sys_dev);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
|
@ -1735,3 +1840,16 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
|
|||
return 0;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
|
||||
|
||||
static int __init cpufreq_core_init(void)
|
||||
{
|
||||
int cpu;
|
||||
|
||||
for_each_possible_cpu(cpu) {
|
||||
per_cpu(policy_cpu, cpu) = -1;
|
||||
init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
core_initcall(cpufreq_core_init);
|
||||
|
|
|
|||
|
|
@ -84,9 +84,6 @@ struct cpufreq_policy {
|
|||
unsigned int policy; /* see above */
|
||||
struct cpufreq_governor *governor; /* see below */
|
||||
|
||||
struct mutex lock; /* CPU ->setpolicy or ->target may
|
||||
only be called once a time */
|
||||
|
||||
struct work_struct update; /* if update_policy() needs to be
|
||||
* called, but you're in IRQ context */
|
||||
|
||||
|
|
@ -172,11 +169,16 @@ extern int __cpufreq_driver_target(struct cpufreq_policy *policy,
|
|||
unsigned int relation);
|
||||
|
||||
|
||||
extern int cpufreq_driver_getavg(struct cpufreq_policy *policy);
|
||||
extern int __cpufreq_driver_getavg(struct cpufreq_policy *policy);
|
||||
|
||||
int cpufreq_register_governor(struct cpufreq_governor *governor);
|
||||
void cpufreq_unregister_governor(struct cpufreq_governor *governor);
|
||||
|
||||
int lock_policy_rwsem_read(int cpu);
|
||||
int lock_policy_rwsem_write(int cpu);
|
||||
void unlock_policy_rwsem_read(int cpu);
|
||||
void unlock_policy_rwsem_write(int cpu);
|
||||
|
||||
|
||||
/*********************************************************************
|
||||
* CPUFREQ DRIVER INTERFACE *
|
||||
|
|
|
|||
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