ACPI / cpuidle: fix max idle state handling with hotplug CPU support

acpi_processor_hotplug() calls acpi_processor_setup_cpuidle_cx()
without calling acpi_processor_setup_cpuidle_states() first so it
is possible that dev->state_count becomes different from
drv->state_count (in case of SMP system with unsupported C2/C3
states + enabled CPU hotplug and num_online_cpus() becoming > 1).

The driver code assumes that cpuidle core will handle such cases
but currently this is untrue (dev->state_count is used only for
handling cpuidle state sysfs entries and drv->state_count is used
for all other cases) and will not be fixed in the future as
dev->state_count is planned to be removed.

Fix the issue by checking for the max supported idle state in
C2/C3 state's ->enter handler (acpi_idle_enter_simple() for C2/C3
and acpi_idle_enter_bm() for C3 + bm_check flag set) and setting
the C1 state (instead of higher states) when needed.

Also remove no longer needed max idle state checks from
acpi_processor_setup_cpuidle_[states,cx]().

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 644516d9bde6..45e3b81d6c29 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -785,6 +785,13 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
         if (unlikely(!pr))
                 return -EINVAL;
 
+#ifdef CONFIG_HOTPLUG_CPU
+        if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
+            !pr->flags.has_cst &&
+            !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
+                return acpi_idle_enter_c1(dev, drv, CPUIDLE_DRIVER_STATE_START);
+#endif
+
         if (cx->entry_method == ACPI_CSTATE_FFH) {
                 if (current_set_polling_and_test())
                         return -EINVAL;
@@ -831,6 +838,13 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
         if (unlikely(!pr))
                 return -EINVAL;
 
+#ifdef CONFIG_HOTPLUG_CPU
+        if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
+            !pr->flags.has_cst &&
+            !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
+                return acpi_idle_enter_c1(dev, drv, CPUIDLE_DRIVER_STATE_START);
+#endif
+
         if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
                 if (drv->safe_state_index >= 0) {
                         return drv->states[drv->safe_state_index].enter(dev,
@@ -932,12 +946,6 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
                 if (!cx->valid)
                         continue;
 
-#ifdef CONFIG_HOTPLUG_CPU
-                if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
-                    !pr->flags.has_cst &&
-                    !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
-                        continue;
-#endif
                 per_cpu(acpi_cstate[count], dev->cpu) = cx;
 
                 count++;
@@ -987,13 +995,6 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
                 if (!cx->valid)
                         continue;
 
-#ifdef CONFIG_HOTPLUG_CPU
-                if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
-                    !pr->flags.has_cst &&
-                    !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
-                        continue;
-#endif
-
                 state = &drv->states[count];
                 snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
                 strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);