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Date: Fri, 12 Jul 2013 03:46:59 +0530
From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To: rjw@...k.pl, viresh.kumar@...aro.org, toralf.foerster@....de,
robert.jarzmik@...el.com, durgadoss.r@...el.com,
tianyu.lan@...el.com, lantianyu1986@...il.com,
dirk.brandewie@...il.com
Cc: stern@...land.harvard.edu,
"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/8] cpufreq: Introduce a flag ('frozen') to separate full vs
temporary init/teardown
During suspend/resume we would like to do a light-weight init/teardown of
CPUs in the cpufreq subsystem and preserve certain things such as sysfs files
etc across suspend/resume transitions. Add a flag called 'frozen' to help
distinguish the full init/teardown sequence from the light-weight one.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---
drivers/cpufreq/cpufreq.c | 66 ++++++++++++++++++++++++++++-----------------
1 file changed, 41 insertions(+), 25 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index efdb607..1128753 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -902,7 +902,7 @@ static void cpufreq_init_policy(struct cpufreq_policy *policy)
#ifdef CONFIG_HOTPLUG_CPU
static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
- struct device *dev)
+ struct device *dev, bool frozen)
{
struct cpufreq_policy *policy;
int ret = 0, has_target = !!cpufreq_driver->target;
@@ -930,13 +930,15 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
__cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
}
+ /* Don't touch sysfs links during light-weight init */
+ if (frozen)
+ return 0;
+
ret = sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
- if (ret) {
+ if (ret)
cpufreq_cpu_put(policy);
- return ret;
- }
- return 0;
+ return ret;
}
#endif
@@ -971,16 +973,8 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
kfree(policy);
}
-/**
- * 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 device *dev, struct subsys_interface *sif)
+static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
+ bool frozen)
{
unsigned int j, cpu = dev->id;
int ret = -ENOMEM;
@@ -1012,7 +1006,8 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
if (cp && cpumask_test_cpu(cpu, cp->related_cpus)) {
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
- return cpufreq_add_policy_cpu(cpu, sibling, dev);
+ return cpufreq_add_policy_cpu(cpu, sibling, dev,
+ frozen);
}
}
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -1078,9 +1073,11 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
}
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
- ret = cpufreq_add_dev_interface(cpu, policy, dev);
- if (ret)
- goto err_out_unregister;
+ if (!frozen) {
+ ret = cpufreq_add_dev_interface(cpu, policy, dev);
+ if (ret)
+ goto err_out_unregister;
+ }
cpufreq_init_policy(policy);
@@ -1111,6 +1108,20 @@ module_out:
return ret;
}
+/**
+ * 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 device *dev, struct subsys_interface *sif)
+{
+ return __cpufreq_add_dev(dev, sif, false);
+}
+
static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
{
int j;
@@ -1129,7 +1140,7 @@ static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
}
static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *data,
- unsigned int old_cpu)
+ unsigned int old_cpu, bool frozen)
{
struct device *cpu_dev;
unsigned long flags;
@@ -1137,6 +1148,11 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *data,
/* first sibling now owns the new sysfs dir */
cpu_dev = get_cpu_device(cpumask_first(data->cpus));
+
+ /* Don't touch sysfs files during light-weight tear-down */
+ if (frozen)
+ return cpu_dev->id;
+
sysfs_remove_link(&cpu_dev->kobj, "cpufreq");
ret = kobject_move(&data->kobj, &cpu_dev->kobj);
if (ret) {
@@ -1168,7 +1184,7 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *data,
* This routine frees the rwsem before returning.
*/
static int __cpufreq_remove_dev(struct device *dev,
- struct subsys_interface *sif)
+ struct subsys_interface *sif, bool frozen)
{
unsigned int cpu = dev->id, cpus, new_cpu;
unsigned long flags;
@@ -1206,11 +1222,11 @@ static int __cpufreq_remove_dev(struct device *dev,
cpumask_clear_cpu(cpu, data->cpus);
unlock_policy_rwsem_write(cpu);
- if (cpu != data->cpu) {
+ if (cpu != data->cpu && !frozen) {
sysfs_remove_link(&dev->kobj, "cpufreq");
} else if (cpus > 1) {
- new_cpu = cpufreq_nominate_new_policy_cpu(data, cpu);
+ new_cpu = cpufreq_nominate_new_policy_cpu(data, cpu, frozen);
if (new_cpu >= 0) {
WARN_ON(lock_policy_rwsem_write(cpu));
update_policy_cpu(data, new_cpu);
@@ -1264,7 +1280,7 @@ static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
if (cpu_is_offline(cpu))
return 0;
- retval = __cpufreq_remove_dev(dev, sif);
+ retval = __cpufreq_remove_dev(dev, sif, false);
return retval;
}
@@ -1990,7 +2006,7 @@ static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
- __cpufreq_remove_dev(dev, NULL);
+ __cpufreq_remove_dev(dev, NULL, false);
break;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
--
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