Merge branch 'linus' into sched/core

Merge reason: branch had an old upstream base (-rc1-ish), but also
              merge to avoid a conflict.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 96 insertions, 106 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 6e2ec0b18948..b90eda8b3440 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -761,6 +761,10 @@ static struct kobj_type ktype_cpufreq = {
  * cpufreq_add_dev - add a CPU device
  *
  * Adds the cpufreq interface for a CPU device.
+ *
+ * The Oracle says: try running cpufreq registration/unregistration concurrently
+ * with with cpu hotplugging and all hell will break loose. Tried to clean this
+ * mess up, but more thorough testing is needed. - Mathieu
  */
 static int cpufreq_add_dev(struct sys_device *sys_dev)
 {
@@ -772,9 +776,6 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
         struct sys_device *cpu_sys_dev;
         unsigned long flags;
         unsigned int j;
-#ifdef CONFIG_SMP
-        struct cpufreq_policy *managed_policy;
-#endif
 
         if (cpu_is_offline(cpu))
                 return 0;
@@ -804,15 +805,12 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
                 goto nomem_out;
         }
         if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL)) {
-                kfree(policy);
                 ret = -ENOMEM;
-                goto nomem_out;
+                goto err_free_policy;
         }
         if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL)) {
-                free_cpumask_var(policy->cpus);
-                kfree(policy);
                 ret = -ENOMEM;
-                goto nomem_out;
+                goto err_free_cpumask;
         }
 
         policy->cpu = cpu;
@@ -820,7 +818,8 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 
         /* Initially set CPU itself as the policy_cpu */
         per_cpu(policy_cpu, cpu) = cpu;
-        lock_policy_rwsem_write(cpu);
+        ret = (lock_policy_rwsem_write(cpu) < 0);
+        WARN_ON(ret);
 
         init_completion(&policy->kobj_unregister);
         INIT_WORK(&policy->update, handle_update);
@@ -833,7 +832,7 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
         ret = cpufreq_driver->init(policy);
         if (ret) {
                 dprintk("initialization failed\n");
-                goto err_out;
+                goto err_unlock_policy;
         }
         policy->user_policy.min = policy->min;
         policy->user_policy.max = policy->max;
@@ -852,21 +851,29 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 #endif
 
         for_each_cpu(j, policy->cpus) {
+                struct cpufreq_policy *managed_policy;
+
                 if (cpu == j)
                         continue;
 
                 /* Check for existing affected CPUs.
                  * They may not be aware of it due to CPU Hotplug.
                  */
-                managed_policy = cpufreq_cpu_get(j);            /* FIXME: Where is this released?  What about error paths? */
+                managed_policy = cpufreq_cpu_get(j);
                 if (unlikely(managed_policy)) {
 
                         /* Set proper policy_cpu */
                         unlock_policy_rwsem_write(cpu);
                         per_cpu(policy_cpu, cpu) = managed_policy->cpu;
 
-                        if (lock_policy_rwsem_write(cpu) < 0)
-                                goto err_out_driver_exit;
+                        if (lock_policy_rwsem_write(cpu) < 0) {
+                                /* Should not go through policy unlock path */
+                                if (cpufreq_driver->exit)
+                                        cpufreq_driver->exit(policy);
+                                ret = -EBUSY;
+                                cpufreq_cpu_put(managed_policy);
+                                goto err_free_cpumask;
+                        }
 
                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
                         cpumask_copy(managed_policy->cpus, policy->cpus);
@@ -877,12 +884,14 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
                         ret = sysfs_create_link(&sys_dev->kobj,
                                                 &managed_policy->kobj,
                                                 "cpufreq");
-                        if (ret)
-                                goto err_out_driver_exit;
-
-                        cpufreq_debug_enable_ratelimit();
-                        ret = 0;
-                        goto err_out_driver_exit; /* call driver->exit() */
+                        if (!ret)
+                                cpufreq_cpu_put(managed_policy);
+                        /*
+                         * Success. We only needed to be added to the mask.
+                         * Call driver->exit() because only the cpu parent of
+                         * the kobj needed to call init().
+                         */
+                        goto out_driver_exit; /* call driver->exit() */
                 }
         }
 #endif
@@ -892,25 +901,25 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
         ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq, &sys_dev->kobj,
                                    "cpufreq");
         if (ret)
-                goto err_out_driver_exit;
+                goto out_driver_exit;
 
         /* set up files for this cpu device */
         drv_attr = cpufreq_driver->attr;
         while ((drv_attr) && (*drv_attr)) {
                 ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
                 if (ret)
-                        goto err_out_driver_exit;
+                        goto err_out_kobj_put;
                 drv_attr++;
         }
         if (cpufreq_driver->get) {
                 ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
                 if (ret)
-                        goto err_out_driver_exit;
+                        goto err_out_kobj_put;
         }
         if (cpufreq_driver->target) {
                 ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
                 if (ret)
-                        goto err_out_driver_exit;
+                        goto err_out_kobj_put;
         }
 
         spin_lock_irqsave(&cpufreq_driver_lock, flags);
@@ -922,18 +931,22 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 
         /* symlink affected CPUs */
         for_each_cpu(j, policy->cpus) {
+                struct cpufreq_policy *managed_policy;
+
                 if (j == cpu)
                         continue;
                 if (!cpu_online(j))
                         continue;
 
                 dprintk("CPU %u already managed, adding link\n", j);
-                cpufreq_cpu_get(cpu);
+                managed_policy = cpufreq_cpu_get(cpu);
                 cpu_sys_dev = get_cpu_sysdev(j);
                 ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
                                         "cpufreq");
-                if (ret)
+                if (ret) {
+                        cpufreq_cpu_put(managed_policy);
                         goto err_out_unregister;
+                }
         }
 
         policy->governor = NULL; /* to assure that the starting sequence is
@@ -965,17 +978,20 @@ err_out_unregister:
                 per_cpu(cpufreq_cpu_data, j) = NULL;
         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
+err_out_kobj_put:
         kobject_put(&policy->kobj);
         wait_for_completion(&policy->kobj_unregister);
 
-err_out_driver_exit:
+out_driver_exit:
         if (cpufreq_driver->exit)
                 cpufreq_driver->exit(policy);
 
-err_out:
+err_unlock_policy:
         unlock_policy_rwsem_write(cpu);
+err_free_cpumask:
+        free_cpumask_var(policy->cpus);
+err_free_policy:
         kfree(policy);
-
 nomem_out:
         module_put(cpufreq_driver->owner);
 module_out:
@@ -1070,8 +1086,6 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 #endif
 
-        unlock_policy_rwsem_write(cpu);
-
         if (cpufreq_driver->target)
                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 
@@ -1088,6 +1102,8 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
         if (cpufreq_driver->exit)
                 cpufreq_driver->exit(data);
 
+        unlock_policy_rwsem_write(cpu);
+
         free_cpumask_var(data->related_cpus);
         free_cpumask_var(data->cpus);
         kfree(data);
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 7fc58af748b4..57490502b21c 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -63,22 +63,20 @@ struct cpu_dbs_info_s {
         unsigned int down_skip;
         unsigned int requested_freq;
         int cpu;
-        unsigned int enable:1;
+        /*
+         * percpu mutex that serializes governor limit change with
+         * do_dbs_timer invocation. We do not want do_dbs_timer to run
+         * when user is changing the governor or limits.
+         */
+        struct mutex timer_mutex;
 };
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
 static unsigned int dbs_enable; /* number of CPUs using this policy */
 
 /*
- * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
- * lock and dbs_mutex. cpu_hotplug lock should always be held before
- * dbs_mutex. If any function that can potentially take cpu_hotplug lock
- * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
- * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
- * is recursive for the same process. -Venki
- * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it
- * would deadlock with cancel_delayed_work_sync(), which is needed for proper
- * raceless workqueue teardown.
+ * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
+ * different CPUs. It protects dbs_enable in governor start/stop.
  */
 static DEFINE_MUTEX(dbs_mutex);
 
@@ -143,9 +141,6 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 
         struct cpufreq_policy *policy;
 
-        if (!this_dbs_info->enable)
-                return 0;
-
         policy = this_dbs_info->cur_policy;
 
         /*
@@ -488,18 +483,12 @@ static void do_dbs_timer(struct work_struct *work)
 
         delay -= jiffies % delay;
 
-        if (lock_policy_rwsem_write(cpu) < 0)
-                return;
-
-        if (!dbs_info->enable) {
-                unlock_policy_rwsem_write(cpu);
-                return;
-        }
+        mutex_lock(&dbs_info->timer_mutex);
 
         dbs_check_cpu(dbs_info);
 
         queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay);
-        unlock_policy_rwsem_write(cpu);
+        mutex_unlock(&dbs_info->timer_mutex);
 }
 
 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
@@ -508,7 +497,6 @@ 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;
         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
         queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,
                                 delay);
@@ -516,7 +504,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
-        dbs_info->enable = 0;
         cancel_delayed_work_sync(&dbs_info->work);
 }
 
@@ -535,9 +522,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                 if ((!cpu_online(cpu)) || (!policy->cur))
                         return -EINVAL;
 
-                if (this_dbs_info->enable) /* Already enabled */
-                        break;
-
                 mutex_lock(&dbs_mutex);
 
                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
@@ -561,6 +545,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                 this_dbs_info->down_skip = 0;
                 this_dbs_info->requested_freq = policy->cur;
 
+                mutex_init(&this_dbs_info->timer_mutex);
                 dbs_enable++;
                 /*
                  * Start the timerschedule work, when this governor
@@ -590,17 +575,19 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                                         &dbs_cpufreq_notifier_block,
                                         CPUFREQ_TRANSITION_NOTIFIER);
                 }
-                dbs_timer_init(this_dbs_info);
-
                 mutex_unlock(&dbs_mutex);
 
+                dbs_timer_init(this_dbs_info);
+
                 break;
 
         case CPUFREQ_GOV_STOP:
-                mutex_lock(&dbs_mutex);
                 dbs_timer_exit(this_dbs_info);
+
+                mutex_lock(&dbs_mutex);
                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
                 dbs_enable--;
+                mutex_destroy(&this_dbs_info->timer_mutex);
 
                 /*
                  * Stop the timerschedule work, when this governor
@@ -616,7 +603,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                 break;
 
         case CPUFREQ_GOV_LIMITS:
-                mutex_lock(&dbs_mutex);
+                mutex_lock(&this_dbs_info->timer_mutex);
                 if (policy->max < this_dbs_info->cur_policy->cur)
                         __cpufreq_driver_target(
                                         this_dbs_info->cur_policy,
@@ -625,7 +612,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         __cpufreq_driver_target(
                                         this_dbs_info->cur_policy,
                                         policy->min, CPUFREQ_RELATION_L);
-                mutex_unlock(&dbs_mutex);
+                mutex_unlock(&this_dbs_info->timer_mutex);
 
                 break;
         }
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 1911d1729353..d6ba14276bb1 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -70,23 +70,21 @@ struct cpu_dbs_info_s {
         unsigned int freq_lo_jiffies;
         unsigned int freq_hi_jiffies;
         int cpu;
-        unsigned int enable:1,
-                sample_type:1;
+        unsigned int sample_type:1;
+        /*
+         * percpu mutex that serializes governor limit change with
+         * do_dbs_timer invocation. We do not want do_dbs_timer to run
+         * when user is changing the governor or limits.
+         */
+        struct mutex timer_mutex;
 };
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
 static unsigned int dbs_enable; /* number of CPUs using this policy */
 
 /*
- * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
- * lock and dbs_mutex. cpu_hotplug lock should always be held before
- * dbs_mutex. If any function that can potentially take cpu_hotplug lock
- * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
- * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
- * is recursive for the same process. -Venki
- * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it
- * would deadlock with cancel_delayed_work_sync(), which is needed for proper
- * raceless workqueue teardown.
+ * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
+ * different CPUs. It protects dbs_enable in governor start/stop.
  */
 static DEFINE_MUTEX(dbs_mutex);
 
@@ -192,13 +190,18 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
         return freq_hi;
 }
 
+static void ondemand_powersave_bias_init_cpu(int cpu)
+{
+        struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
+        dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
+        dbs_info->freq_lo = 0;
+}
+
 static void ondemand_powersave_bias_init(void)
 {
         int i;
         for_each_online_cpu(i) {
-                struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
-                dbs_info->freq_table = cpufreq_frequency_get_table(i);
-                dbs_info->freq_lo = 0;
+                ondemand_powersave_bias_init_cpu(i);
         }
 }
 
@@ -240,12 +243,10 @@ static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
         unsigned int input;
         int ret;
         ret = sscanf(buf, "%u", &input);
+        if (ret != 1)
+                return -EINVAL;
 
         mutex_lock(&dbs_mutex);
-        if (ret != 1) {
-                mutex_unlock(&dbs_mutex);
-                return -EINVAL;
-        }
         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
         mutex_unlock(&dbs_mutex);
 
@@ -259,13 +260,12 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
         int ret;
         ret = sscanf(buf, "%u", &input);
 
-        mutex_lock(&dbs_mutex);
         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
                         input < MIN_FREQUENCY_UP_THRESHOLD) {
-                mutex_unlock(&dbs_mutex);
                 return -EINVAL;
         }
 
+        mutex_lock(&dbs_mutex);
         dbs_tuners_ins.up_threshold = input;
         mutex_unlock(&dbs_mutex);
 
@@ -363,9 +363,6 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
         struct cpufreq_policy *policy;
         unsigned int j;
 
-        if (!this_dbs_info->enable)
-                return;
-
         this_dbs_info->freq_lo = 0;
         policy = this_dbs_info->cur_policy;
 
@@ -493,14 +490,7 @@ static void do_dbs_timer(struct work_struct *work)
         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 
         delay -= jiffies % delay;
-
-        if (lock_policy_rwsem_write(cpu) < 0)
-                return;
-
-        if (!dbs_info->enable) {
-                unlock_policy_rwsem_write(cpu);
-                return;
-        }
+        mutex_lock(&dbs_info->timer_mutex);
 
         /* Common NORMAL_SAMPLE setup */
         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
@@ -517,7 +507,7 @@ static void do_dbs_timer(struct work_struct *work)
                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
         }
         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
-        unlock_policy_rwsem_write(cpu);
+        mutex_unlock(&dbs_info->timer_mutex);
 }
 
 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
@@ -526,8 +516,6 @@ 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_DEFERRABLE(&dbs_info->work, do_dbs_timer);
         queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
@@ -536,7 +524,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
-        dbs_info->enable = 0;
         cancel_delayed_work_sync(&dbs_info->work);
 }
 
@@ -555,19 +542,15 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                 if ((!cpu_online(cpu)) || (!policy->cur))
                         return -EINVAL;
 
-                if (this_dbs_info->enable) /* Already enabled */
-                        break;
-
                 mutex_lock(&dbs_mutex);
-                dbs_enable++;
 
                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
                 if (rc) {
-                        dbs_enable--;
                         mutex_unlock(&dbs_mutex);
                         return rc;
                 }
 
+                dbs_enable++;
                 for_each_cpu(j, policy->cpus) {
                         struct cpu_dbs_info_s *j_dbs_info;
                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
@@ -581,6 +564,8 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         }
                 }
                 this_dbs_info->cpu = cpu;
+                ondemand_powersave_bias_init_cpu(cpu);
+                mutex_init(&this_dbs_info->timer_mutex);
                 /*
                  * Start the timerschedule work, when this governor
                  * is used for first time
@@ -598,29 +583,31 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                                 max(min_sampling_rate,
                                     latency * LATENCY_MULTIPLIER);
                 }
-                dbs_timer_init(this_dbs_info);
-
                 mutex_unlock(&dbs_mutex);
+
+                dbs_timer_init(this_dbs_info);
                 break;
 
         case CPUFREQ_GOV_STOP:
-                mutex_lock(&dbs_mutex);
                 dbs_timer_exit(this_dbs_info);
+
+                mutex_lock(&dbs_mutex);
                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
+                mutex_destroy(&this_dbs_info->timer_mutex);
                 dbs_enable--;
                 mutex_unlock(&dbs_mutex);
 
                 break;
 
         case CPUFREQ_GOV_LIMITS:
-                mutex_lock(&dbs_mutex);
+                mutex_lock(&this_dbs_info->timer_mutex);
                 if (policy->max < this_dbs_info->cur_policy->cur)
                         __cpufreq_driver_target(this_dbs_info->cur_policy,
                                 policy->max, CPUFREQ_RELATION_H);
                 else if (policy->min > this_dbs_info->cur_policy->cur)
                         __cpufreq_driver_target(this_dbs_info->cur_policy,
                                 policy->min, CPUFREQ_RELATION_L);
-                mutex_unlock(&dbs_mutex);
+                mutex_unlock(&this_dbs_info->timer_mutex);
                 break;
         }
         return 0;