From: "shin, jacob" <jacob.shin@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxx>
Cc: davej@xxxxxxxxxx
---
---
drivers/cpufreq/cpufreq.c | 51 ++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 49 insertions(+), 2 deletions(-)
Index: linux/drivers/cpufreq/cpufreq.c
===================================================================
--- linux.orig/drivers/cpufreq/cpufreq.c
+++ linux/drivers/cpufreq/cpufreq.c
@@ -6,6 +6,8 @@
*
* Oct 2005 - Ashok Raj <ashok.raj@xxxxxxxxx>
* Added handling for CPU hotplug
+ * Feb 2006 - Jacob Shin <jacob.shin@xxxxxxx>
+ * 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_d
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_d
* 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_d
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_d
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 sy
*/
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);
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