ACPICA: Delete recursive feature of ACPI Global Lock

Completed a new design and implementation for
the ACPI Global Lock support. On the OS side, the global
lock is now treated as a standard AML mutex. Previously,
multiple OS threads could acquire the global lock
simultaneously, but this could cause the BIOS to be starved
by the lock in cases such as the Embedded Controller driver,
where there is a tight coupling between the OS and the BIOS.

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 10 insertions, 6 deletions

diff --git a/drivers/acpi/utilities/utdelete.c b/drivers/acpi/utilities/utdelete.c
index 9d3f1149ba21..af8e65f17fb7 100644
--- a/drivers/acpi/utilities/utdelete.c
+++ b/drivers/acpi/utilities/utdelete.c
@@ -158,16 +158,20 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
                                   "***** Mutex %p, OS Mutex %p\n",
                                   object, object->mutex.os_mutex));
 
-                if (object->mutex.os_mutex != ACPI_GLOBAL_LOCK) {
-                        acpi_ex_unlink_mutex(object);
-                        acpi_os_delete_mutex(object->mutex.os_mutex);
-                } else {
-                        /* Global Lock "mutex" is actually a counting semaphore */
+                if (object->mutex.os_mutex == acpi_gbl_global_lock_mutex) {
+
+                        /* Global Lock has extra semaphore */
 
                         (void)
                             acpi_os_delete_semaphore
                             (acpi_gbl_global_lock_semaphore);
                         acpi_gbl_global_lock_semaphore = NULL;
+
+                        acpi_os_delete_mutex(object->mutex.os_mutex);
+                        acpi_gbl_global_lock_mutex = NULL;
+                } else {
+                        acpi_ex_unlink_mutex(object);
+                        acpi_os_delete_mutex(object->mutex.os_mutex);
                 }
                 break;
 
diff --git a/drivers/acpi/utilities/utglobal.c b/drivers/acpi/utilities/utglobal.c
index 014030af8b50..103845213e22 100644
--- a/drivers/acpi/utilities/utglobal.c
+++ b/drivers/acpi/utilities/utglobal.c
@@ -795,8 +795,8 @@ void acpi_ut_init_globals(void)
         /* Global Lock support */
 
         acpi_gbl_global_lock_semaphore = NULL;
+        acpi_gbl_global_lock_mutex = NULL;
         acpi_gbl_global_lock_acquired = FALSE;
-        acpi_gbl_global_lock_thread_count = 0;
         acpi_gbl_global_lock_handle = 0;
 
         /* Miscellaneous variables */