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, 46 insertions, 110 deletions

diff --git a/drivers/acpi/executer/exmutex.c b/drivers/acpi/executer/exmutex.c
index bf90f04..f1dd1b0 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 28aef3e..3b9736a 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;