ACPI: Thermal: Drop concurrent thermal checks

Fix for #3686, where get_temperature() may cause thermal notify, which
causes one more get_temperature().

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 15d5fdc66a9..69ec73b0239 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 = {
@@ -721,11 +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));
 
@@ -816,8 +821,8 @@ static void acpi_thermal_check(void *data)
                         add_timer(&(tz->timer));
                 }
         }
-
-        return;
+      unlock:
+        mutex_unlock(&tz->lock);
 }
 
 /* --------------------------------------------------------------------------
@@ -1254,7 +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;
@@ -1324,7 +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;
 }