When the CPU hotplug notification comes in via ACPI notify()
cpu_data of the core is not yet initialized (the core did never
get booted and set up).
This leads to errors in throttling and (if acpi_idle is used
as cpuidle driver) to not set up cpu idle subsystem.
-> Only bring up ACPI sysfs at that time
-> Initialize the rest (throttling, cpuidle,...) when a hotplugged
core is onlined the first time
Sidenote:
When starting on this, Xen patches were applied on the code base
I worked on. I later realized that changing:
static acpi_status acpi_processor_hotadd_init(acpi_handle handle, int *p_cpu);
to only passing the processor object:
static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr);
came from Xen patches, but is convenient to have for physical cpu hotplugging
and took that over.
Signed-off-by: Thomas Renninger <trenn@xxxxxxx>
CC: Len Brown <lenb@xxxxxxxxxx>
CC: linux-acpi@xxxxxxxxxxxxxxx
---
drivers/acpi/processor_driver.c | 75 +++++++++++++++++++++++++++++---------
include/acpi/processor.h | 1 +
2 files changed, 58 insertions(+), 18 deletions(-)
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 546951a..16f26b8 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -82,9 +82,9 @@ MODULE_LICENSE("GPL");
static int acpi_processor_add(struct acpi_device *device);
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(acpi_handle handle, int *p_cpu);
+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},
@@ -324,10 +324,8 @@ static int acpi_processor_get_info(struct acpi_device *device)
* they are physically not present.
*/
if (pr->id == -1) {
- if (ACPI_FAILURE
- (acpi_processor_hotadd_init(pr->handle, &pr->id))) {
+ if (ACPI_FAILURE(acpi_processor_hotadd_init(pr)))
return -ENODEV;
- }
}
/*
* On some boxes several processors use the same processor bus id.
@@ -425,10 +423,28 @@ 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_cst_has_changed(pr);
- acpi_processor_reevaluate_tstate(pr, action);
- acpi_processor_tstate_has_changed(pr);
+ /* CPU got 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);
+ }
+ } 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 */
@@ -442,7 +458,15 @@ 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;
@@ -548,6 +572,13 @@ 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;
+
result = acpi_processor_start(pr);
if (result)
goto err_remove_sysfs;
@@ -737,20 +768,28 @@ processor_walk_namespace_cb(acpi_handle handle,
return (AE_OK);
}
-static acpi_status acpi_processor_hotadd_init(acpi_handle handle, int *p_cpu)
+static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
{
-
- if (!is_processor_present(handle)) {
+ if (!is_processor_present(pr->handle))
return AE_ERROR;
- }
- if (acpi_map_lsapic(handle, p_cpu))
+ if (acpi_map_lsapic(pr->handle, &pr->id))
return AE_ERROR;
- if (arch_register_cpu(*p_cpu)) {
- acpi_unmap_lsapic(*p_cpu);
+ if (arch_register_cpu(pr->id)) {
+ acpi_unmap_lsapic(pr->id);
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;
}
@@ -765,7 +804,7 @@ static int acpi_processor_handle_eject(struct acpi_processor *pr)
return (0);
}
#else
-static acpi_status acpi_processor_hotadd_init(acpi_handle handle, int *p_cpu)
+static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
{
return AE_ERROR;
}
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 67055f1..2a2d3ab 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 {
--
1.7.6.1
--
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