ACPI processor hotplug: Delay acpi_processor_start() call for hotplugged cores

Delay the setting up of features (cpuidle, throttling by calling
acpi_processor_start()) to the time when the hotplugged
core got onlined the first time and got fully
initialized.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

3 files changed, 67 insertions, 8 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index bec55937cf1..2b805d7ef31 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -84,7 +84,7 @@ static int acpi_processor_remove(struct acpi_device *device, int type);
 static void acpi_processor_notify(struct acpi_device *device, u32 event);
 static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr);
 static int acpi_processor_handle_eject(struct acpi_processor *pr);
-
+static int acpi_processor_start(struct acpi_processor *pr);
 
 static const struct acpi_device_id processor_device_ids[] = {
         {ACPI_PROCESSOR_OBJECT_HID, 0},
@@ -423,10 +423,29 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
         struct acpi_processor *pr = per_cpu(processors, cpu);
 
         if (action == CPU_ONLINE && pr) {
-                acpi_processor_ppc_has_changed(pr, 0);
-                acpi_processor_hotplug(pr);
-                acpi_processor_reevaluate_tstate(pr, action);
-                acpi_processor_tstate_has_changed(pr);
+                /* CPU got physically hotplugged and onlined the first time:
+                 * Initialize missing things
+                 */
+                if (pr->flags.need_hotplug_init) {
+                        struct cpuidle_driver *idle_driver =
+                                cpuidle_get_driver();
+
+                        printk(KERN_INFO "Will online and init hotplugged "
+                               "CPU: %d\n", pr->id);
+                        WARN(acpi_processor_start(pr), "Failed to start CPU:"
+                                " %d\n", pr->id);
+                        pr->flags.need_hotplug_init = 0;
+                        if (idle_driver && !strcmp(idle_driver->name,
+                                                   "intel_idle")) {
+                                intel_idle_cpu_init(pr->id);
+                        }
+                /* Normal CPU soft online event */
+                } else {
+                        acpi_processor_ppc_has_changed(pr, 0);
+                        acpi_processor_cst_has_changed(pr);
+                        acpi_processor_reevaluate_tstate(pr, action);
+                        acpi_processor_tstate_has_changed(pr);
+                }
         }
         if (action == CPU_DEAD && pr) {
                 /* invalidate the flag.throttling after one CPU is offline */
@@ -440,7 +459,15 @@ static struct notifier_block acpi_cpu_notifier =
             .notifier_call = acpi_cpu_soft_notify,
 };
 
-static int __cpuinit acpi_processor_start(struct acpi_processor *pr)
+/*
+ * acpi_processor_start() is called by the cpu_hotplug_notifier func:
+ * acpi_cpu_soft_notify(). Getting it __cpuinit{data} is difficult, the
+ * root cause seem to be that acpi_processor_uninstall_hotplug_notify()
+ * is in the module_exit (__exit) func. Allowing acpi_processor_start()
+ * to not be in __cpuinit section, but being called from __cpuinit funcs
+ * via __ref looks like the right thing to do here.
+ */
+static __ref int acpi_processor_start(struct acpi_processor *pr)
 {
         struct acpi_device *device = per_cpu(processor_device_array, pr->id);
         int result = 0;
@@ -491,7 +518,12 @@ err_power_exit:
         return result;
 }
 
-
+/*
+ * Do not put anything in here which needs the core to be online.
+ * For example MSR access or setting up things which check for cpuinfo_x86
+ * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc.
+ * Such things have to be put in and set up above in acpi_processor_start()
+ */
 static int __cpuinit acpi_processor_add(struct acpi_device *device)
 {
         struct acpi_processor *pr = NULL;
@@ -546,6 +578,21 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
                 result = -EFAULT;
                 goto err_free_cpumask;
         }
+
+        /*
+         * Do not start hotplugged CPUs now, but when they
+         * are onlined the first time
+         */
+        if (pr->flags.need_hotplug_init)
+                return 0;
+
+        /*
+         * Do not start hotplugged CPUs now, but when they
+         * are onlined the first time
+         */
+        if (pr->flags.need_hotplug_init)
+                return 0;
+
         result = acpi_processor_start(pr);
         if (result)
                 goto err_remove_sysfs;
@@ -751,6 +798,17 @@ static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
                 return AE_ERROR;
         }
 
+        /* CPU got hot-plugged, but cpu_data is not initialized yet
+         * Set flag to delay cpu_idle/throttling initialization
+         * in:
+         * acpi_processor_add()
+         *   acpi_processor_get_info()
+         * and do it when the CPU gets online the first time
+         * TBD: Cleanup above functions and try to do this more elegant.
+         */
+        printk(KERN_INFO "CPU %d got hotplugged\n", pr->id);
+        pr->flags.need_hotplug_init = 1;
+
         return AE_OK;
 }
 
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 20bce51c2e8..54ab97bae04 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -527,7 +527,7 @@ int intel_idle_cpu_init(int cpu)
 
         return 0;
 }
-
+EXPORT_SYMBOL_GPL(intel_idle_cpu_init);
 
 static int __init intel_idle_init(void)
 {
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 610f6fb1bbc..8cf7e98a2c7 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -195,6 +195,7 @@ struct acpi_processor_flags {
         u8 has_cst:1;
         u8 power_setup_done:1;
         u8 bm_rld_set:1;
+        u8 need_hotplug_init:1;
 };
 
 struct acpi_processor {