// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
*
* Module Name: exmutex - ASL Mutex Acquire/Release functions
*
* Copyright (C) 2000 - 2025, Intel Corp.
*
*****************************************************************************/
#include <acpi/acpi.h>
#include "accommon.h"
#include "acinterp.h"
#include "acevents.h"
#define _COMPONENT ACPI_EXECUTER
ACPI_MODULE_NAME(
"exmutex")
/* Local prototypes */
static void
acpi_ex_link_mutex(
union acpi_operand_object *obj_desc,
struct acpi_thread_state *thread);
/*******************************************************************************
*
* FUNCTION: acpi_ex_unlink_mutex
*
* PARAMETERS: obj_desc - The mutex to be unlinked
*
* RETURN: None
*
* DESCRIPTION: Remove a mutex from the "AcquiredMutex" list
*
******************************************************************************/
void acpi_ex_unlink_mutex(
union acpi_operand_object *obj_desc)
{
struct acpi_thread_state *thread = obj_desc->mutex.owner_thread;
if (!thread) {
return;
}
/* Doubly linked list */
if (obj_desc->mutex.next) {
(obj_desc->mutex.next)->mutex.prev = obj_desc->mutex.prev;
}
if (obj_desc->mutex.prev) {
(obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next;
/*
* Migrate the previous sync level associated with this mutex to
* the previous mutex on the list so that it may be preserved.
* This handles the case where several mutexes have been acquired
* at the same level, but are not released in opposite order.
*/
(obj_desc->mutex.prev)->mutex.original_sync_level =
obj_desc->mutex.original_sync_level;
}
else {
thread->acquired_mutex_list = obj_desc->mutex.next;
}
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_link_mutex
*
* PARAMETERS: obj_desc - The mutex to be linked
* thread - Current executing thread object
*
* RETURN: None
*
* DESCRIPTION: Add a mutex to the "AcquiredMutex" list for this walk
*
******************************************************************************/
static void
acpi_ex_link_mutex(
union acpi_operand_object *obj_desc,
struct acpi_thread_state *thread)
{
union acpi_operand_object *list_head;
list_head = thread->acquired_mutex_list;
/* This object will be the first object in the list */
obj_desc->mutex.prev = NULL;
obj_desc->mutex.next = list_head;
/* Update old first object to point back to this object */
if (list_head) {
list_head->mutex.prev = obj_desc;
}
/* Update list head */
thread->acquired_mutex_list = obj_desc;
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_acquire_mutex_object
*
* PARAMETERS: timeout - Timeout in milliseconds
* obj_desc - Mutex object
* thread_id - Current thread state
*
* RETURN: Status
*
* DESCRIPTION: Acquire an AML mutex, low-level interface. Provides a common
* path that supports multiple acquires by the same thread.
*
* MUTEX: Interpreter must be locked
*
* NOTE: This interface is called from three places:
* 1) From acpi_ex_acquire_mutex, via an AML Acquire() operator
* 2) From acpi_ex_acquire_global_lock when an AML Field access requires the
* global lock
* 3) From the external interface, acpi_acquire_global_lock
*
******************************************************************************/
acpi_status
acpi_ex_acquire_mutex_object(u16 timeout,
union acpi_operand_object *obj_desc,
acpi_thread_id thread_id)
{
acpi_status status;
ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex_object, obj_desc);
if (!obj_desc) {
return_ACPI_STATUS(AE_BAD_PARAMETER);
}
/* Support for multiple acquires by the owning thread */
if (obj_desc->mutex.thread_id == thread_id) {
/*
* 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. Special case for Global Lock */
if (obj_desc == acpi_gbl_global_lock_mutex) {
status = acpi_ev_acquire_global_lock(timeout);
}
else {
status =
acpi_ex_system_wait_mutex(obj_desc->mutex.os_mutex,
timeout);
}
if (ACPI_FAILURE(status)) {
/* Includes failure from a timeout on time_desc */
return_ACPI_STATUS(status);
}
/* Acquired the mutex: update mutex object */
obj_desc->mutex.thread_id = thread_id;
obj_desc->mutex.acquisition_depth = 1;
obj_desc->mutex.original_sync_level = 0;
obj_desc->mutex.owner_thread = NULL;
/* Used only for AML Acquire() */
return_ACPI_STATUS(AE_OK);
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_acquire_mutex
*
* PARAMETERS: time_desc - Timeout integer
* obj_desc - Mutex object
* walk_state - Current method execution state
*
* RETURN: Status
*
* DESCRIPTION: Acquire an AML mutex
*
******************************************************************************/
acpi_status
acpi_ex_acquire_mutex(
union acpi_operand_object *time_desc,
union acpi_operand_object *obj_desc,
struct acpi_walk_state *walk_state)
{
acpi_status status;
ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex, obj_desc);
if (!obj_desc) {
return_ACPI_STATUS(AE_BAD_PARAMETER);
}
/* Must have a valid thread state struct */
if (!walk_state->thread) {
ACPI_ERROR((AE_INFO,
"Cannot acquire Mutex [%4.4s], null thread info",
acpi_ut_get_node_name(obj_desc->mutex.node)));
return_ACPI_STATUS(AE_AML_INTERNAL);
}
/*
* Current sync level must be less than or equal to the sync level
* of the mutex. This mechanism provides some deadlock prevention.
*/
if (walk_state->thread->current_sync_level > obj_desc->mutex.sync_level) {
ACPI_ERROR((AE_INFO,
"Cannot acquire Mutex [%4.4s], "
"current SyncLevel is too large (%u)",
acpi_ut_get_node_name(obj_desc->mutex.node),
walk_state->thread->current_sync_level));
return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
}
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Acquiring: Mutex SyncLevel %u, Thread SyncLevel %u, "
"Depth %u TID %p\n",
obj_desc->mutex.sync_level,
walk_state->thread->current_sync_level,
obj_desc->mutex.acquisition_depth,
walk_state->thread));
status = acpi_ex_acquire_mutex_object((u16)time_desc->integer.value,
obj_desc,
walk_state->thread->thread_id);
if (ACPI_SUCCESS(status) && obj_desc->mutex.acquisition_depth == 1) {
/* Save Thread object, original/current sync levels */
obj_desc->mutex.owner_thread = walk_state->thread;
obj_desc->mutex.original_sync_level =
walk_state->thread->current_sync_level;
walk_state->thread->current_sync_level =
obj_desc->mutex.sync_level;
/* Link the mutex to the current thread for force-unlock at method exit */
acpi_ex_link_mutex(obj_desc, walk_state->thread);
}
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Acquired: Mutex SyncLevel %u, Thread SyncLevel %u, Depth %u\n",
obj_desc->mutex.sync_level,
walk_state->thread->current_sync_level,
obj_desc->mutex.acquisition_depth));
return_ACPI_STATUS(status);
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_release_mutex_object
*
* PARAMETERS: obj_desc - The object descriptor for this op
*
* RETURN: Status
*
* DESCRIPTION: Release a previously acquired Mutex, low level interface.
* Provides a common path that supports multiple releases (after
* previous multiple acquires) by the same thread.
*
* MUTEX: Interpreter must be locked
*
* NOTE: This interface is called from three places:
* 1) From acpi_ex_release_mutex, via an AML Acquire() operator
* 2) From acpi_ex_release_global_lock when an AML Field access requires the
* global lock
* 3) From the external interface, acpi_release_global_lock
*
******************************************************************************/
acpi_status acpi_ex_release_mutex_object(
union acpi_operand_object *obj_desc)
{
acpi_status status = AE_OK;
ACPI_FUNCTION_TRACE(ex_release_mutex_object);
if (obj_desc->mutex.acquisition_depth == 0) {
return_ACPI_STATUS(AE_NOT_ACQUIRED);
}
/* Match multiple Acquires with multiple Releases */
obj_desc->mutex.acquisition_depth--;
if (obj_desc->mutex.acquisition_depth != 0) {
/* Just decrement the depth and return */
return_ACPI_STATUS(AE_OK);
}
if (obj_desc->mutex.owner_thread) {
/* Unlink the mutex from the owner's list */
acpi_ex_unlink_mutex(obj_desc);
obj_desc->mutex.owner_thread = NULL;
}
/* Release the mutex, special case for Global Lock */
if (obj_desc == acpi_gbl_global_lock_mutex) {
status = acpi_ev_release_global_lock();
}
else {
acpi_os_release_mutex(obj_desc->mutex.os_mutex);
}
/* Clear mutex info */
obj_desc->mutex.thread_id = 0;
return_ACPI_STATUS(status);
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_release_mutex
*
* PARAMETERS: obj_desc - The object descriptor for this op
* walk_state - Current method execution state
*
* RETURN: Status
*
* DESCRIPTION: Release a previously acquired Mutex.
*
******************************************************************************/
acpi_status
acpi_ex_release_mutex(
union acpi_operand_object *obj_desc,
struct acpi_walk_state *walk_state)
{
u8 previous_sync_level;
struct acpi_thread_state *owner_thread;
acpi_status status = AE_OK;
ACPI_FUNCTION_TRACE(ex_release_mutex);
if (!obj_desc) {
return_ACPI_STATUS(AE_BAD_PARAMETER);
}
owner_thread = obj_desc->mutex.owner_thread;
/* The mutex must have been previously acquired in order to release it */
if (!owner_thread) {
ACPI_ERROR((AE_INFO,
"Cannot release Mutex [%4.4s], not acquired",
acpi_ut_get_node_name(obj_desc->mutex.node)));
return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED);
}
/* Must have a valid thread ID */
if (!walk_state->thread) {
ACPI_ERROR((AE_INFO,
"Cannot release Mutex [%4.4s], null thread info",
acpi_ut_get_node_name(obj_desc->mutex.node)));
return_ACPI_STATUS(AE_AML_INTERNAL);
}
/*
* The Mutex is owned, but this thread must be the owner.
* Special case for Global Lock, any thread can release
*/
if ((owner_thread->thread_id != walk_state->thread->thread_id) &&
(obj_desc != acpi_gbl_global_lock_mutex)) {
ACPI_ERROR((AE_INFO,
"Thread %u cannot release Mutex [%4.4s] acquired by thread %u",
(u32)walk_state->thread->thread_id,
acpi_ut_get_node_name(obj_desc->mutex.node),
(u32)owner_thread->thread_id));
return_ACPI_STATUS(AE_AML_NOT_OWNER);
}
/*
* The sync level of the mutex must be equal to the current sync level. In
* other words, the current level means that at least one mutex at that
* level is currently being held. Attempting to release a mutex of a
* different level can only mean that the mutex ordering rule is being
* violated. This behavior is clarified in ACPI 4.0 specification.
*/
if (obj_desc->mutex.sync_level != owner_thread->current_sync_level) {
ACPI_ERROR((AE_INFO,
"Cannot release Mutex [%4.4s], SyncLevel mismatch: "
"mutex %u current %u",
acpi_ut_get_node_name(obj_desc->mutex.node),
obj_desc->mutex.sync_level,
walk_state->thread->current_sync_level));
return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
}
/*
* Get the previous sync_level from the head of the acquired mutex list.
* This handles the case where several mutexes at the same level have been
* acquired, but are not released in reverse order.
*/
previous_sync_level =
owner_thread->acquired_mutex_list->mutex.original_sync_level;
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Releasing: Object SyncLevel %u, Thread SyncLevel %u, "
"Prev SyncLevel %u, Depth %u TID %p\n",
obj_desc->mutex.sync_level,
walk_state->thread->current_sync_level,
previous_sync_level,
obj_desc->mutex.acquisition_depth,
walk_state->thread));
status = acpi_ex_release_mutex_object(obj_desc);
if (ACPI_FAILURE(status)) {
return_ACPI_STATUS(status);
}
if (obj_desc->mutex.acquisition_depth == 0) {
/* Restore the previous sync_level */
owner_thread->current_sync_level = previous_sync_level;
}
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Released: Object SyncLevel %u, Thread SyncLevel, %u, "
"Prev SyncLevel %u, Depth %u\n",
obj_desc->mutex.sync_level,
walk_state->thread->current_sync_level,
previous_sync_level,
obj_desc->mutex.acquisition_depth));
return_ACPI_STATUS(status);
}
/*******************************************************************************
*
* FUNCTION: acpi_ex_release_all_mutexes
*
* PARAMETERS: thread - Current executing thread object
*
* RETURN: Status
*
* DESCRIPTION: Release all mutexes held by this thread
*
* NOTE: This function is called as the thread is exiting the interpreter.
* Mutexes are not released when an individual control method is exited, but
* only when the parent thread actually exits the interpreter. This allows one
* method to acquire a mutex, and a different method to release it, as long as
* this is performed underneath a single parent control method.
*
******************************************************************************/
void acpi_ex_release_all_mutexes(
struct acpi_thread_state *thread)
{
union acpi_operand_object *next = thread->acquired_mutex_list;
union acpi_operand_object *obj_desc;
ACPI_FUNCTION_TRACE(ex_release_all_mutexes);
/* Traverse the list of owned mutexes, releasing each one */
while (next) {
obj_desc = next;
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
"Mutex [%4.4s] force-release, SyncLevel %u Depth %u\n",
obj_desc->mutex.node->name.ascii,
obj_desc->mutex.sync_level,
obj_desc->mutex.acquisition_depth));
/* Release the mutex, special case for Global Lock */
if (obj_desc == acpi_gbl_global_lock_mutex) {
/* Ignore errors */
(
void)acpi_ev_release_global_lock();
}
else {
acpi_os_release_mutex(obj_desc->mutex.os_mutex);
}
/* Update Thread sync_level (Last mutex is the important one) */
thread->current_sync_level =
obj_desc->mutex.original_sync_level;
/* Mark mutex unowned */
next = obj_desc->mutex.next;
obj_desc->mutex.prev = NULL;
obj_desc->mutex.next = NULL;
obj_desc->mutex.acquisition_depth = 0;
obj_desc->mutex.owner_thread = NULL;
obj_desc->mutex.thread_id = 0;
}
return_VOID;
}
