ACPI: Check the returned value of set_cpus_allowed_ptr before T-state operation

Now before it executes the T-state operation on one CPU, it will try to
migrate to the target CPU. Especially this is required on the system that
uses the MSR_IA32_THERMAL_CONTROL register to switch T-state.
But unfortunately it doesn't check whether the migration is successful or not.
In such case we will get/set the incorrect T-state on the offline CPU as
it fails in the migration to the offline CPU.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 21 insertions, 3 deletions

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index ff3632717c51..ffc859c61393 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -876,7 +876,11 @@ static int acpi_processor_get_throttling(struct acpi_processor *pr)
          */
         cpumask_copy(saved_mask, &current->cpus_allowed);
         /* FIXME: use work_on_cpu() */
-        set_cpus_allowed_ptr(current, cpumask_of(pr->id));
+        if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
+                /* Can't migrate to the target pr->id CPU. Exit */
+                free_cpumask_var(saved_mask);
+                return -ENODEV;
+        }
         ret = pr->throttling.acpi_processor_get_throttling(pr);
         /* restore the previous state */
         set_cpus_allowed_ptr(current, saved_mask);
@@ -1051,6 +1055,14 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
                 return -ENOMEM;
         }
 
+        if (cpu_is_offline(pr->id)) {
+                /*
+                 * the cpu pointed by pr->id is offline. Unnecessary to change
+                 * the throttling state any more.
+                 */
+                return -ENODEV;
+        }
+
         cpumask_copy(saved_mask, &current->cpus_allowed);
         t_state.target_state = state;
         p_throttling = &(pr->throttling);
@@ -1074,7 +1086,11 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
          */
         if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
                 /* FIXME: use work_on_cpu() */
-                set_cpus_allowed_ptr(current, cpumask_of(pr->id));
+                if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
+                        /* Can't migrate to the pr->id CPU. Exit */
+                        ret = -ENODEV;
+                        goto exit;
+                }
                 ret = p_throttling->acpi_processor_set_throttling(pr,
                                                 t_state.target_state, force);
         } else {
@@ -1106,7 +1122,8 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
                         }
                         t_state.cpu = i;
                         /* FIXME: use work_on_cpu() */
-                        set_cpus_allowed_ptr(current, cpumask_of(i));
+                        if (set_cpus_allowed_ptr(current, cpumask_of(i)))
+                                continue;
                         ret = match_pr->throttling.
                                 acpi_processor_set_throttling(
                                 match_pr, t_state.target_state, force);
@@ -1126,6 +1143,7 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
         /* restore the previous state */
         /* FIXME: use work_on_cpu() */
         set_cpus_allowed_ptr(current, saved_mask);
+exit:
         free_cpumask_var(online_throttling_cpus);
         free_cpumask_var(saved_mask);
         return ret;