6 files changed, 131 insertions, 190 deletions

diff --git a/drivers/acpi/events/evmisc.c b/drivers/acpi/events/evmisc.c
index bf63edc6608d..f82b81cc1838 100644
--- a/drivers/acpi/events/evmisc.c
+++ b/drivers/acpi/events/evmisc.c
@@ -298,19 +298,13 @@ static void ACPI_SYSTEM_XFACE acpi_ev_global_lock_thread(void *context)
 {
         acpi_status status;
 
-        /* Signal threads that are waiting for the lock */
+        /* Signal the thread that is waiting for the lock */
 
-        if (acpi_gbl_global_lock_thread_count) {
+        /* Send a unit to the semaphore */
 
-                /* Send sufficient units to the semaphore */
-
-                status =
-                    acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore,
-                                             acpi_gbl_global_lock_thread_count);
-                if (ACPI_FAILURE(status)) {
-                        ACPI_ERROR((AE_INFO,
-                                    "Could not signal Global Lock semaphore"));
-                }
+        status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
+        if (ACPI_FAILURE(status)) {
+                ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
         }
 }
 
@@ -333,7 +327,8 @@ static u32 acpi_ev_global_lock_handler(void *context)
         u8 acquired = FALSE;
 
         /*
-         * Attempt to get the lock
+         * Attempt to get the lock.
+         *
          * If we don't get it now, it will be marked pending and we will
          * take another interrupt when it becomes free.
          */
@@ -341,6 +336,7 @@ static u32 acpi_ev_global_lock_handler(void *context)
         if (acquired) {
 
                 /* Got the lock, now wake all threads waiting for it */
+
                 acpi_gbl_global_lock_acquired = TRUE;
                 acpi_ev_global_lock_thread(context);
         }
@@ -399,6 +395,16 @@ acpi_status acpi_ev_init_global_lock_handler(void)
  *
  * DESCRIPTION: Attempt to gain ownership of the Global Lock.
  *
+ * MUTEX:       Interpreter must be locked
+ *
+ * Note: The original implementation allowed multiple threads to "acquire" the
+ * Global Lock, and the OS would hold the lock until the last thread had
+ * released it. However, this could potentially starve the BIOS out of the
+ * lock, especially in the case where there is a tight handshake between the
+ * Embedded Controller driver and the BIOS. Therefore, this implementation
+ * allows only one thread to acquire the HW Global Lock at a time, and makes
+ * the global lock appear as a standard mutex on the OS side.
+ *
  *****************************************************************************/
 
 acpi_status acpi_ev_acquire_global_lock(u16 timeout)
@@ -408,27 +414,25 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout)
 
         ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
 
-#ifndef ACPI_APPLICATION
-        /* Make sure that we actually have a global lock */
-
-        if (!acpi_gbl_global_lock_present) {
-                return_ACPI_STATUS(AE_NO_GLOBAL_LOCK);
+        /*
+         * Only one thread can acquire the GL at a time, the global_lock_mutex
+         * enforces this. This interface releases the interpreter if we must wait.
+         */
+        status = acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex, timeout);
+        if (ACPI_FAILURE(status)) {
+                return_ACPI_STATUS(status);
         }
-#endif
-
-        /* One more thread wants the global lock */
-
-        acpi_gbl_global_lock_thread_count++;
 
         /*
-         * If we (OS side vs. BIOS side) have the hardware lock already,
-         * we are done
+         * Make sure that a global lock actually exists. If not, just treat
+         * the lock as a standard mutex.
          */
-        if (acpi_gbl_global_lock_acquired) {
+        if (!acpi_gbl_global_lock_present) {
+                acpi_gbl_global_lock_acquired = TRUE;
                 return_ACPI_STATUS(AE_OK);
         }
 
-        /* We must acquire the actual hardware lock */
+        /* Attempt to acquire the actual hardware lock */
 
         ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock, acquired);
         if (acquired) {
@@ -436,25 +440,24 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout)
                 /* We got the lock */
 
                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
-                                  "Acquired the HW Global Lock\n"));
+                                  "Acquired hardware Global Lock\n"));
 
                 acpi_gbl_global_lock_acquired = TRUE;
                 return_ACPI_STATUS(AE_OK);
         }
 
         /*
-         * Did not get the lock.  The pending bit was set above, and we must now
+         * Did not get the lock. The pending bit was set above, and we must now
          * wait until we get the global lock released interrupt.
          */
-        ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Waiting for the HW Global Lock\n"));
+        ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Waiting for hardware Global Lock\n"));
 
         /*
-         * Acquire the global lock semaphore first.
-         * Since this wait will block, we must release the interpreter
+         * Wait for handshake with the global lock interrupt handler.
+         * This interface releases the interpreter if we must wait.
          */
-        status =
-            acpi_ex_system_wait_semaphore(acpi_gbl_global_lock_semaphore,
-                                          timeout);
+        status = acpi_ex_system_wait_semaphore(acpi_gbl_global_lock_semaphore,
+                                               ACPI_WAIT_FOREVER);
         return_ACPI_STATUS(status);
 }
 
@@ -477,38 +480,40 @@ acpi_status acpi_ev_release_global_lock(void)
 
         ACPI_FUNCTION_TRACE(ev_release_global_lock);
 
-        if (!acpi_gbl_global_lock_thread_count) {
+        /* Lock must be acquired */
+
+        if (!acpi_gbl_global_lock_acquired) {
                 ACPI_WARNING((AE_INFO,
-                              "Cannot release HW Global Lock, it has not been acquired"));
+                              "Cannot release the ACPI Global Lock, it has not been acquired"));
                 return_ACPI_STATUS(AE_NOT_ACQUIRED);
         }
 
-        /* One fewer thread has the global lock */
+        if (acpi_gbl_global_lock_present) {
 
-        acpi_gbl_global_lock_thread_count--;
-        if (acpi_gbl_global_lock_thread_count) {
+                /* Allow any thread to release the lock */
 
-                /* There are still some threads holding the lock, cannot release */
+                ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock,
+                                         pending);
 
-                return_ACPI_STATUS(AE_OK);
+                /*
+                 * If the pending bit was set, we must write GBL_RLS to the control
+                 * register
+                 */
+                if (pending) {
+                        status =
+                            acpi_set_register(ACPI_BITREG_GLOBAL_LOCK_RELEASE,
+                                              1, ACPI_MTX_LOCK);
+                }
+
+                ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
+                                  "Released hardware Global Lock\n"));
         }
 
-        /*
-         * No more threads holding lock, we can do the actual hardware
-         * release
-         */
-        ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock, pending);
         acpi_gbl_global_lock_acquired = FALSE;
 
-        /*
-         * If the pending bit was set, we must write GBL_RLS to the control
-         * register
-         */
-        if (pending) {
-                status = acpi_set_register(ACPI_BITREG_GLOBAL_LOCK_RELEASE,
-                                           1, ACPI_MTX_LOCK);
-        }
+        /* Release the local GL mutex */
 
+        acpi_os_release_mutex(acpi_gbl_global_lock_mutex);
         return_ACPI_STATUS(status);
 }
 
diff --git a/drivers/acpi/executer/exmutex.c b/drivers/acpi/executer/exmutex.c
index bf90f04f2c60..f1dd1b07d482 100644
--- a/drivers/acpi/executer/exmutex.c
+++ b/drivers/acpi/executer/exmutex.c
@@ -44,6 +44,7 @@
 
 #include <acpi/acpi.h>
 #include <acpi/acinterp.h>
+#include <acpi/acevents.h>
 
 #define _COMPONENT          ACPI_EXECUTER
 ACPI_MODULE_NAME("exmutex")
@@ -150,7 +151,7 @@ acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
                 return_ACPI_STATUS(AE_BAD_PARAMETER);
         }
 
-        /* Sanity check -- we must have a valid thread ID */
+        /* Sanity check: we must have a valid thread ID */
 
         if (!walk_state->thread) {
                 ACPI_ERROR((AE_INFO,
@@ -174,24 +175,28 @@ acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
         /* Support for multiple acquires by the owning thread */
 
         if (obj_desc->mutex.owner_thread) {
-
-                /* Special case for Global Lock, allow all threads */
-
-                if ((obj_desc->mutex.owner_thread->thread_id ==
-                     walk_state->thread->thread_id) ||
-                    (obj_desc->mutex.os_mutex == ACPI_GLOBAL_LOCK)) {
+                if (obj_desc->mutex.owner_thread->thread_id ==
+                    walk_state->thread->thread_id) {
                         /*
-                         * The mutex is already owned by this thread,
-                         * just increment the acquisition depth
+                         * The mutex is already owned by this thread, just increment the
+                         * acquisition depth
                          */
                         obj_desc->mutex.acquisition_depth++;
                         return_ACPI_STATUS(AE_OK);
                 }
         }
 
-        /* Acquire the mutex, wait if necessary */
+        /* Acquire the mutex, wait if necessary. Special case for Global Lock */
+
+        if (obj_desc->mutex.os_mutex == acpi_gbl_global_lock_mutex) {
+                status =
+                    acpi_ev_acquire_global_lock((u16) time_desc->integer.value);
+        } else {
+                status = acpi_ex_system_wait_mutex(obj_desc->mutex.os_mutex,
+                                                   (u16) time_desc->integer.
+                                                   value);
+        }
 
-        status = acpi_ex_system_acquire_mutex(time_desc, obj_desc);
         if (ACPI_FAILURE(status)) {
 
                 /* Includes failure from a timeout on time_desc */
@@ -211,7 +216,6 @@ acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
         /* Link the mutex to the current thread for force-unlock at method exit */
 
         acpi_ex_link_mutex(obj_desc, walk_state->thread);
-
         return_ACPI_STATUS(AE_OK);
 }
 
@@ -232,7 +236,7 @@ acpi_status
 acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                       struct acpi_walk_state *walk_state)
 {
-        acpi_status status;
+        acpi_status status = AE_OK;
 
         ACPI_FUNCTION_TRACE(ex_release_mutex);
 
@@ -249,7 +253,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                 return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED);
         }
 
-        /* Sanity check -- we must have a valid thread ID */
+        /* Sanity check: we must have a valid thread ID */
 
         if (!walk_state->thread) {
                 ACPI_ERROR((AE_INFO,
@@ -264,7 +268,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
          */
         if ((obj_desc->mutex.owner_thread->thread_id !=
              walk_state->thread->thread_id)
-            && (obj_desc->mutex.os_mutex != ACPI_GLOBAL_LOCK)) {
+            && (obj_desc->mutex.os_mutex != acpi_gbl_global_lock_mutex)) {
                 ACPI_ERROR((AE_INFO,
                             "Thread %lX cannot release Mutex [%4.4s] acquired by thread %lX",
                             (unsigned long)walk_state->thread->thread_id,
@@ -274,8 +278,8 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
         }
 
         /*
-         * The sync level of the mutex must be less than or
-         * equal to the current sync level
+         * The sync level of the mutex must be less than or equal to the current
+         * sync level
          */
         if (obj_desc->mutex.sync_level > walk_state->thread->current_sync_level) {
                 ACPI_ERROR((AE_INFO,
@@ -298,11 +302,15 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
 
         acpi_ex_unlink_mutex(obj_desc);
 
-        /* Release the mutex */
+        /* Release the mutex, special case for Global Lock */
 
-        status = acpi_ex_system_release_mutex(obj_desc);
+        if (obj_desc->mutex.os_mutex == acpi_gbl_global_lock_mutex) {
+                status = acpi_ev_release_global_lock();
+        } else {
+                acpi_os_release_mutex(obj_desc->mutex.os_mutex);
+        }
 
-        /* Update the mutex and walk state, restore sync_level before acquire */
+        /* Update the mutex and restore sync_level */
 
         obj_desc->mutex.owner_thread = NULL;
         walk_state->thread->current_sync_level =
@@ -326,34 +334,38 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
 void acpi_ex_release_all_mutexes(struct acpi_thread_state *thread)
 {
         union acpi_operand_object *next = thread->acquired_mutex_list;
-        union acpi_operand_object *this;
-        acpi_status status;
+        union acpi_operand_object *obj_desc;
 
         ACPI_FUNCTION_ENTRY();
 
         /* Traverse the list of owned mutexes, releasing each one */
 
         while (next) {
-                this = next;
-                next = this->mutex.next;
+                obj_desc = next;
+                next = obj_desc->mutex.next;
+
+                obj_desc->mutex.prev = NULL;
+                obj_desc->mutex.next = NULL;
+                obj_desc->mutex.acquisition_depth = 1;
+
+                /* Release the mutex, special case for Global Lock */
 
-                this->mutex.acquisition_depth = 1;
-                this->mutex.prev = NULL;
-                this->mutex.next = NULL;
+                if (obj_desc->mutex.os_mutex == acpi_gbl_global_lock_mutex) {
 
-                /* Release the mutex */
+                        /* Ignore errors */
 
-                status = acpi_ex_system_release_mutex(this);
-                if (ACPI_FAILURE(status)) {
-                        continue;
+                        (void)acpi_ev_release_global_lock();
+                } else {
+                        acpi_os_release_mutex(obj_desc->mutex.os_mutex);
                 }
 
                 /* Mark mutex unowned */
 
-                this->mutex.owner_thread = NULL;
+                obj_desc->mutex.owner_thread = NULL;
 
                 /* Update Thread sync_level (Last mutex is the important one) */
 
-                thread->current_sync_level = this->mutex.original_sync_level;
+                thread->current_sync_level =
+                    obj_desc->mutex.original_sync_level;
         }
 }
diff --git a/drivers/acpi/executer/exsystem.c b/drivers/acpi/executer/exsystem.c
index 28aef3e69ecc..3b9736a3e1b7 100644
--- a/drivers/acpi/executer/exsystem.c
+++ b/drivers/acpi/executer/exsystem.c
@@ -227,82 +227,6 @@ acpi_status acpi_ex_system_do_suspend(acpi_integer how_long)
 
 /*******************************************************************************
  *
- * FUNCTION:    acpi_ex_system_acquire_mutex
- *
- * PARAMETERS:  time_desc       - Maximum time to wait for the mutex
- *              obj_desc        - The object descriptor for this op
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Provides an access point to perform synchronization operations
- *              within the AML.  This function will cause a lock to be generated
- *              for the Mutex pointed to by obj_desc.
- *
- ******************************************************************************/
-
-acpi_status
-acpi_ex_system_acquire_mutex(union acpi_operand_object * time_desc,
-                             union acpi_operand_object * obj_desc)
-{
-        acpi_status status = AE_OK;
-
-        ACPI_FUNCTION_TRACE_PTR(ex_system_acquire_mutex, obj_desc);
-
-        if (!obj_desc) {
-                return_ACPI_STATUS(AE_BAD_PARAMETER);
-        }
-
-        /* Support for the _GL_ Mutex object -- go get the global lock */
-
-        if (obj_desc->mutex.os_mutex == ACPI_GLOBAL_LOCK) {
-                status =
-                    acpi_ev_acquire_global_lock((u16) time_desc->integer.value);
-                return_ACPI_STATUS(status);
-        }
-
-        status = acpi_ex_system_wait_mutex(obj_desc->mutex.os_mutex,
-                                           (u16) time_desc->integer.value);
-        return_ACPI_STATUS(status);
-}
-
-/*******************************************************************************
- *
- * FUNCTION:    acpi_ex_system_release_mutex
- *
- * PARAMETERS:  obj_desc        - The object descriptor for this op
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Provides an access point to perform synchronization operations
- *              within the AML.  This operation is a request to release a
- *              previously acquired Mutex.  If the Mutex variable is set then
- *              it will be decremented.
- *
- ******************************************************************************/
-
-acpi_status acpi_ex_system_release_mutex(union acpi_operand_object *obj_desc)
-{
-        acpi_status status = AE_OK;
-
-        ACPI_FUNCTION_TRACE(ex_system_release_mutex);
-
-        if (!obj_desc) {
-                return_ACPI_STATUS(AE_BAD_PARAMETER);
-        }
-
-        /* Support for the _GL_ Mutex object -- release the global lock */
-
-        if (obj_desc->mutex.os_mutex == ACPI_GLOBAL_LOCK) {
-                status = acpi_ev_release_global_lock();
-                return_ACPI_STATUS(status);
-        }
-
-        acpi_os_release_mutex(obj_desc->mutex.os_mutex);
-        return_ACPI_STATUS(AE_OK);
-}
-
-/*******************************************************************************
- *
  * FUNCTION:    acpi_ex_system_signal_event
  *
  * PARAMETERS:  obj_desc        - The object descriptor for this op
@@ -314,7 +238,7 @@ acpi_status acpi_ex_system_release_mutex(union acpi_operand_object *obj_desc)
  *
  ******************************************************************************/
 
-acpi_status acpi_ex_system_signal_event(union acpi_operand_object *obj_desc)
+acpi_status acpi_ex_system_signal_event(union acpi_operand_object * obj_desc)
 {
         acpi_status status = AE_OK;
 
diff --git a/drivers/acpi/namespace/nsaccess.c b/drivers/acpi/namespace/nsaccess.c
index c1c6c236df9a..b2ef6730be81 100644
--- a/drivers/acpi/namespace/nsaccess.c
+++ b/drivers/acpi/namespace/nsaccess.c
@@ -195,31 +195,27 @@ acpi_status acpi_ns_root_initialize(void)
                                 obj_desc->mutex.sync_level =
                                     (u8) (ACPI_TO_INTEGER(val) - 1);
 
-                                if (ACPI_STRCMP(init_val->name, "_GL_") == 0) {
-
-                                        /* Create a counting semaphore for the global lock */
+                                /* Create a mutex */
+
+                                status =
+                                    acpi_os_create_mutex(&obj_desc->mutex.
+                                                         os_mutex);
+                                if (ACPI_FAILURE(status)) {
+                                        acpi_ut_remove_reference(obj_desc);
+                                        goto unlock_and_exit;
+                                }
 
-                                        status =
-                                            acpi_os_create_semaphore
-                                            (ACPI_NO_UNIT_LIMIT, 1,
-                                             &acpi_gbl_global_lock_semaphore);
-                                        if (ACPI_FAILURE(status)) {
-                                                acpi_ut_remove_reference
-                                                    (obj_desc);
-                                                goto unlock_and_exit;
-                                        }
+                                /* Special case for ACPI Global Lock */
 
-                                        /* Mark this mutex as very special */
+                                if (ACPI_STRCMP(init_val->name, "_GL_") == 0) {
+                                        acpi_gbl_global_lock_mutex =
+                                            obj_desc->mutex.os_mutex;
 
-                                        obj_desc->mutex.os_mutex =
-                                            ACPI_GLOBAL_LOCK;
-                                } else {
-                                        /* Create a mutex */
+                                        /* Create additional counting semaphore for global lock */
 
                                         status =
-                                            acpi_os_create_mutex(&obj_desc->
-                                                                 mutex.
-                                                                 os_mutex);
+                                            acpi_os_create_semaphore(1, 1,
+                                                                     &acpi_gbl_global_lock_semaphore);
                                         if (ACPI_FAILURE(status)) {
                                                 acpi_ut_remove_reference
                                                     (obj_desc);
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 */