1 files changed, 67 insertions, 18 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 109d62ccf651..6c6121b85a54 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -4,6 +4,9 @@
  *  Copyright (C) 2001 Russell King
  *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
  *
+ *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
+ *                      Added handling for CPU hotplug
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -36,13 +39,6 @@ static struct cpufreq_policy	*cpufreq_cpu_data[NR_CPUS];
 static DEFINE_SPINLOCK(cpufreq_driver_lock);
 
 
-/* we keep a copy of all ->add'ed CPU's struct sys_device here;
- * as it is only accessed in ->add and ->remove, no lock or reference
- * count is necessary.
- */
-static struct sys_device        *cpu_sys_devices[NR_CPUS];
-
-
 /* internal prototypes */
 static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
 static void handle_update(void *data);
@@ -574,6 +570,9 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
         unsigned long flags;
         unsigned int j;
 
+        if (cpu_is_offline(cpu))
+                return 0;
+
         cpufreq_debug_disable_ratelimit();
         dprintk("adding CPU %u\n", cpu);
 
@@ -582,7 +581,6 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
          * CPU because it is in the same boat. */
         policy = cpufreq_cpu_get(cpu);
         if (unlikely(policy)) {
-                cpu_sys_devices[cpu] = sys_dev;
                 dprintk("CPU already managed, adding link\n");
                 sysfs_create_link(&sys_dev->kobj, &policy->kobj, "cpufreq");
                 cpufreq_debug_enable_ratelimit();
@@ -657,7 +655,6 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
         }
 
         module_put(cpufreq_driver->owner);
-        cpu_sys_devices[cpu] = sys_dev;
         dprintk("initialization complete\n");
         cpufreq_debug_enable_ratelimit();
         
@@ -682,7 +679,7 @@ err_out:
 
 nomem_out:
         module_put(cpufreq_driver->owner);
- module_out:
+module_out:
         cpufreq_debug_enable_ratelimit();
         return ret;
 }
@@ -698,6 +695,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
         unsigned int cpu = sys_dev->id;
         unsigned long flags;
         struct cpufreq_policy *data;
+        struct sys_device *cpu_sys_dev;
 #ifdef CONFIG_SMP
         unsigned int j;
 #endif
@@ -710,7 +708,6 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
 
         if (!data) {
                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
-                cpu_sys_devices[cpu] = NULL;
                 cpufreq_debug_enable_ratelimit();
                 return -EINVAL;
         }
@@ -725,14 +722,12 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
                 dprintk("removing link\n");
                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
                 sysfs_remove_link(&sys_dev->kobj, "cpufreq");
-                cpu_sys_devices[cpu] = NULL;
                 cpufreq_cpu_put(data);
                 cpufreq_debug_enable_ratelimit();
                 return 0;
         }
 #endif
 
-        cpu_sys_devices[cpu] = NULL;
 
         if (!kobject_get(&data->kobj)) {
                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -761,7 +756,8 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
                         if (j == cpu)
                                 continue;
                         dprintk("removing link for cpu %u\n", j);
-                        sysfs_remove_link(&cpu_sys_devices[j]->kobj, "cpufreq");
+                        cpu_sys_dev = get_cpu_sysdev(j);
+                        sysfs_remove_link(&cpu_sys_dev->kobj, "cpufreq");
                         cpufreq_cpu_put(data);
                 }
         }
@@ -772,7 +768,6 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
         down(&data->lock);
         if (cpufreq_driver->target)
                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
-        cpufreq_driver->target = NULL;
         up(&data->lock);
 
         kobject_unregister(&data->kobj);
@@ -1119,17 +1114,30 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
                             unsigned int relation)
 {
         int retval = -EINVAL;
-        lock_cpu_hotplug();
+
+        /*
+         * Converted the lock_cpu_hotplug to preempt_disable()
+         * and preempt_enable(). This is a bit kludgy and relies on how cpu
+         * hotplug works. All we need is a guarantee that cpu hotplug won't make
+         * progress on any cpu. Once we do preempt_disable(), this would ensure
+         * that hotplug threads don't get onto this cpu, thereby delaying
+         * the cpu remove process.
+         *
+         * We removed the lock_cpu_hotplug since we need to call this function
+         * via cpu hotplug callbacks, which result in locking the cpu hotplug
+         * thread itself. Agree this is not very clean, cpufreq community
+         * could improve this if required. - Ashok Raj <ashok.raj@intel.com>
+         */
+        preempt_disable();
         dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
                 target_freq, relation);
         if (cpu_online(policy->cpu) && cpufreq_driver->target)
                 retval = cpufreq_driver->target(policy, target_freq, relation);
-        unlock_cpu_hotplug();
+        preempt_enable();
         return retval;
 }
 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
 
-
 int cpufreq_driver_target(struct cpufreq_policy *policy,
                           unsigned int target_freq,
                           unsigned int relation)
@@ -1416,6 +1424,45 @@ int cpufreq_update_policy(unsigned int cpu)
 }
 EXPORT_SYMBOL(cpufreq_update_policy);
 
+static int __cpuinit 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;
+
+        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.
+                         */
+                        policy = cpufreq_cpu_data[cpu];
+                        if (policy) {
+                                cpufreq_driver_target(policy, policy->min,
+                                                CPUFREQ_RELATION_H);
+                        }
+                        break;
+                case CPU_DEAD:
+                        cpufreq_remove_dev(sys_dev);
+                        break;
+                }
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block cpufreq_cpu_notifier =
+{
+    .notifier_call = cpufreq_cpu_callback,
+};
 
 /*********************************************************************
  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
@@ -1476,6 +1523,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
         }
 
         if (!ret) {
+                register_cpu_notifier(&cpufreq_cpu_notifier);
                 dprintk("driver %s up and running\n", driver_data->name);
                 cpufreq_debug_enable_ratelimit();
         }
@@ -1507,6 +1555,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
         dprintk("unregistering driver %s\n", driver->name);
 
         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
+        unregister_cpu_notifier(&cpufreq_cpu_notifier);
 
         spin_lock_irqsave(&cpufreq_driver_lock, flags);
         cpufreq_driver = NULL;