cpufreq: Separate CPU device registration from CPU online

To separate the CPU online interface from the CPU device
registration, split cpufreq_online() out of cpufreq_add_dev()
and make cpufreq_cpu_callback() call the former, while
cpufreq_add_dev() itself will only be used as the CPU device
addition subsystem interface callback.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Suggested-by: Russell King <linux@arm.linux.org.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 47 insertions, 43 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 0618522d4863..0d46b557c016 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1191,36 +1191,15 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy, bool notify)
         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_online(unsigned int cpu)
 {
-        unsigned int j, cpu = dev->id;
-        int ret;
         struct cpufreq_policy *policy;
-        unsigned long flags;
         bool recover_policy;
+        unsigned long flags;
+        unsigned int j;
+        int ret;
 
-        pr_debug("adding CPU %u\n", cpu);
-
-        if (cpu_is_offline(cpu)) {
-                /*
-                 * Only possible if we are here from the subsys_interface add
-                 * callback.  A hotplug notifier will follow and we will handle
-                 * it as CPU online then.  For now, just create the sysfs link,
-                 * unless there is no policy or the link is already present.
-                 */
-                policy = per_cpu(cpufreq_cpu_data, cpu);
-                return policy && !cpumask_test_and_set_cpu(cpu, policy->real_cpus)
-                        ? add_cpu_dev_symlink(policy, cpu) : 0;
-        }
+        pr_debug("%s: bringing CPU%u online\n", __func__, cpu);
 
         /* Check if this CPU already has a policy to manage it */
         policy = per_cpu(cpufreq_cpu_data, cpu);
@@ -1377,6 +1356,35 @@ out_free_policy:
         return ret;
 }
 
+/**
+ * cpufreq_add_dev - the cpufreq interface for a CPU device.
+ * @dev: CPU device.
+ * @sif: Subsystem interface structure pointer (not used)
+ */
+static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
+{
+        unsigned cpu = dev->id;
+        int ret;
+
+        dev_dbg(dev, "%s: adding CPU%u\n", __func__, cpu);
+
+        if (cpu_online(cpu)) {
+                ret = cpufreq_online(cpu);
+        } else {
+                /*
+                 * A hotplug notifier will follow and we will handle it as CPU
+                 * online then.  For now, just create the sysfs link, unless
+                 * there is no policy or the link is already present.
+                 */
+                struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
+
+                ret = policy && !cpumask_test_and_set_cpu(cpu, policy->real_cpus)
+                        ? add_cpu_dev_symlink(policy, cpu) : 0;
+        }
+
+        return ret;
+}
+
 static void cpufreq_offline_prepare(unsigned int cpu)
 {
         struct cpufreq_policy *policy;
@@ -2340,27 +2348,23 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb,
                                         unsigned long action, void *hcpu)
 {
         unsigned int cpu = (unsigned long)hcpu;
-        struct device *dev;
 
-        dev = get_cpu_device(cpu);
-        if (dev) {
-                switch (action & ~CPU_TASKS_FROZEN) {
-                case CPU_ONLINE:
-                        cpufreq_add_dev(dev, NULL);
-                        break;
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_ONLINE:
+                cpufreq_online(cpu);
+                break;
 
-                case CPU_DOWN_PREPARE:
-                        cpufreq_offline_prepare(cpu);
-                        break;
+        case CPU_DOWN_PREPARE:
+                cpufreq_offline_prepare(cpu);
+                break;
 
-                case CPU_POST_DEAD:
-                        cpufreq_offline_finish(cpu);
-                        break;
+        case CPU_POST_DEAD:
+                cpufreq_offline_finish(cpu);
+                break;
 
-                case CPU_DOWN_FAILED:
-                        cpufreq_add_dev(dev, NULL);
-                        break;
-                }
+        case CPU_DOWN_FAILED:
+                cpufreq_online(cpu);
+                break;
         }
         return NOTIFY_OK;
 }