1 files changed, 18 insertions, 10 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index bc6d5866ef98..69ec73b0239d 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -195,6 +195,7 @@ struct acpi_thermal {
         struct acpi_thermal_trips trips;
         struct acpi_handle_list devices;
         struct timer_list timer;
+        struct mutex lock;
 };
 
 static const struct file_operations acpi_thermal_state_fops = {
@@ -711,6 +712,7 @@ static void acpi_thermal_check(void *data)
         int result = 0;
         struct acpi_thermal *tz = data;
         unsigned long sleep_time = 0;
+        unsigned long timeout_jiffies = 0;
         int i = 0;
         struct acpi_thermal_state state;
 
@@ -720,11 +722,15 @@ static void acpi_thermal_check(void *data)
                 return;
         }
 
+        /* Check if someone else is already running */
+        if (!mutex_trylock(&tz->lock))
+                return;
+
         state = tz->state;
 
         result = acpi_thermal_get_temperature(tz);
         if (result)
-                return;
+                goto unlock;
 
         memset(&tz->state, 0, sizeof(tz->state));
 
@@ -787,10 +793,13 @@ static void acpi_thermal_check(void *data)
          * a thermal event occurs).  Note that _TSP and _TZD values are
          * given in 1/10th seconds (we must covert to milliseconds).
          */
-        if (tz->state.passive)
+        if (tz->state.passive) {
                 sleep_time = tz->trips.passive.tsp * 100;
-        else if (tz->polling_frequency > 0)
+                timeout_jiffies =  jiffies + (HZ * sleep_time) / 1000;
+        } else if (tz->polling_frequency > 0) {
                 sleep_time = tz->polling_frequency * 100;
+                timeout_jiffies =  round_jiffies(jiffies + (HZ * sleep_time) / 1000);
+        }
 
         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "%s: temperature[%lu] sleep[%lu]\n",
                           tz->name, tz->temperature, sleep_time));
@@ -804,17 +813,16 @@ static void acpi_thermal_check(void *data)
                         del_timer(&(tz->timer));
         } else {
                 if (timer_pending(&(tz->timer)))
-                        mod_timer(&(tz->timer),
-                                        jiffies + (HZ * sleep_time) / 1000);
+                        mod_timer(&(tz->timer), timeout_jiffies);
                 else {
                         tz->timer.data = (unsigned long)tz;
                         tz->timer.function = acpi_thermal_run;
-                        tz->timer.expires = jiffies + (HZ * sleep_time) / 1000;
+                        tz->timer.expires = timeout_jiffies;
                         add_timer(&(tz->timer));
                 }
         }
-
-        return;
+      unlock:
+        mutex_unlock(&tz->lock);
 }
 
 /* --------------------------------------------------------------------------
@@ -1251,7 +1259,7 @@ static int acpi_thermal_add(struct acpi_device *device)
         strcpy(acpi_device_name(device), ACPI_THERMAL_DEVICE_NAME);
         strcpy(acpi_device_class(device), ACPI_THERMAL_CLASS);
         acpi_driver_data(device) = tz;
-
+        mutex_init(&tz->lock);
         result = acpi_thermal_get_info(tz);
         if (result)
                 goto end;
@@ -1321,7 +1329,7 @@ static int acpi_thermal_remove(struct acpi_device *device, int type)
         }
 
         acpi_thermal_remove_fs(device);
-
+        mutex_destroy(&tz->lock);
         kfree(tz);
         return 0;
 }