3 files changed, 63 insertions, 0 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 85e48047d7b0..c8a0ca2af839 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -478,8 +478,13 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
         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);
         }
+        if (action == CPU_DEAD && pr) {
+                /* invalidate the flag.throttling after one CPU is offline */
+                acpi_processor_reevaluate_tstate(pr, action);
+        }
         return NOTIFY_OK;
 }
 
diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index ffc859c61393..4305d560b065 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -370,6 +370,58 @@ int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
 }
 
 /*
+ * This function is used to reevaluate whether the T-state is valid
+ * after one CPU is onlined/offlined.
+ * It is noted that it won't reevaluate the following properties for
+ * the T-state.
+ *      1. Control method.
+ *      2. the number of supported T-state
+ *      3. TSD domain
+ */
+void acpi_processor_reevaluate_tstate(struct acpi_processor *pr,
+                                        unsigned long action)
+{
+        int result = 0;
+
+        if (action == CPU_DEAD) {
+                /* When one CPU is offline, the T-state throttling
+                 * will be invalidated.
+                 */
+                pr->flags.throttling = 0;
+                return;
+        }
+        /* the following is to recheck whether the T-state is valid for
+         * the online CPU
+         */
+        if (!pr->throttling.state_count) {
+                /* If the number of T-state is invalid, it is
+                 * invalidated.
+                 */
+                pr->flags.throttling = 0;
+                return;
+        }
+        pr->flags.throttling = 1;
+
+        /* Disable throttling (if enabled).  We'll let subsequent
+         * policy (e.g.thermal) decide to lower performance if it
+         * so chooses, but for now we'll crank up the speed.
+         */
+
+        result = acpi_processor_get_throttling(pr);
+        if (result)
+                goto end;
+
+        if (pr->throttling.state) {
+                result = acpi_processor_set_throttling(pr, 0, false);
+                if (result)
+                        goto end;
+        }
+
+end:
+        if (result)
+                pr->flags.throttling = 0;
+}
+/*
  * _PTC - Processor Throttling Control (and status) register location
  */
 static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 1b62102fbb67..55192ac0cede 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -324,6 +324,12 @@ int acpi_processor_tstate_has_changed(struct acpi_processor *pr);
 int acpi_processor_get_throttling_info(struct acpi_processor *pr);
 extern int acpi_processor_set_throttling(struct acpi_processor *pr,
                                          int state, bool force);
+/*
+ * Reevaluate whether the T-state is invalid after one cpu is
+ * onlined/offlined. In such case the flags.throttling will be updated.
+ */
+extern void acpi_processor_reevaluate_tstate(struct acpi_processor *pr,
+                        unsigned long action);
 extern const struct file_operations acpi_processor_throttling_fops;
 extern void acpi_processor_throttling_init(void);
 /* in processor_idle.c */