exmutex.c

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/******************************************************************************
 *
 * Module Name: exmutex - ASL Mutex Acquire/Release functions
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#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);
    }

    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);
    }

    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 (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)
{
    acpi_status status = AE_OK;
    u8 previous_sync_level;
    struct acpi_thread_state *owner_thread;

    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. */
    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;

    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;
    }

    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_ENTRY();

    /* Traverse the list of owned mutexes, releasing each one */

    while (next) {
        obj_desc = next;
        next = obj_desc->mutex.next;

        obj_desc->mutex.prev = NULL;
        obj_desc->mutex.next = NULL;
        obj_desc->mutex.acquisition_depth = 0;

        /* 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);
        }

        /* Mark mutex unowned */

        obj_desc->mutex.owner_thread = NULL;
        obj_desc->mutex.thread_id = 0;

        /* Update Thread sync_level (Last mutex is the important one) */

        thread->current_sync_level =
            obj_desc->mutex.original_sync_level;
    }
}