[CPUFREQ] Fix handling for CPU hotplug

This patch adds proper logic to cpufreq driver in order to handle
CPU Hotplug.

When CPUs go on/offline, the affected CPUs data, cpufreq_policy->cpus,
is not updated properly. This causes sysfs directories and symlinks to
be in an incorrect state after few CPU on/offlines.

Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 49 insertions, 2 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index cb7d6e0db759..aed80e6aec6d 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -6,6 +6,8 @@
  *
  *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
  *      Added handling for CPU hotplug
+ *  Feb 2006 - Jacob Shin <jacob.shin@amd.com>
+ *      Fix handling for CPU hotplug -- affected CPUs
  *
  * 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
@@ -573,8 +575,12 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
         struct cpufreq_policy new_policy;
         struct cpufreq_policy *policy;
         struct freq_attr **drv_attr;
+        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;
@@ -587,8 +593,7 @@ 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)) {
-                dprintk("CPU already managed, adding link\n");
-                sysfs_create_link(&sys_dev->kobj, &policy->kobj, "cpufreq");
+                cpufreq_cpu_put(policy);
                 cpufreq_debug_enable_ratelimit();
                 return 0;
         }
@@ -623,6 +628,32 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
                 goto err_out;
         }
 
+#ifdef CONFIG_SMP
+        for_each_cpu_mask(j, policy->cpus) {
+                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);
+                if (unlikely(managed_policy)) {
+                        spin_lock_irqsave(&cpufreq_driver_lock, flags);
+                        managed_policy->cpus = policy->cpus;
+                        cpufreq_cpu_data[cpu] = managed_policy;
+                        spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+                        dprintk("CPU already managed, adding link\n");
+                        sysfs_create_link(&sys_dev->kobj,
+                                          &managed_policy->kobj, "cpufreq");
+
+                        cpufreq_debug_enable_ratelimit();
+                        mutex_unlock(&policy->lock);
+                        ret = 0;
+                        goto err_out_driver_exit; /* call driver->exit() */
+                }
+        }
+#endif
         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 
         /* prepare interface data */
@@ -650,6 +681,21 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
         for_each_cpu_mask(j, policy->cpus)
                 cpufreq_cpu_data[j] = policy;
         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+        /* symlink affected CPUs */
+        for_each_cpu_mask(j, policy->cpus) {
+                if (j == cpu)
+                        continue;
+                if (!cpu_online(j))
+                        continue;
+
+                dprintk("CPU already managed, adding link\n");
+                cpufreq_cpu_get(cpu);
+                cpu_sys_dev = get_cpu_sysdev(j);
+                sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
+                                  "cpufreq");
+        }
+
         policy->governor = NULL; /* to assure that the starting sequence is
                                   * run in cpufreq_set_policy */
         mutex_unlock(&policy->lock);
@@ -728,6 +774,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
          */
         if (unlikely(cpu != data->cpu)) {
                 dprintk("removing link\n");
+                cpu_clear(cpu, data->cpus);
                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
                 sysfs_remove_link(&sys_dev->kobj, "cpufreq");
                 cpufreq_cpu_put(data);