nswalk.c

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/******************************************************************************
 *
 * Module Name: nswalk - Functions for walking the ACPI namespace
 *
 *****************************************************************************/

/*
 * 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 "acnamesp.h"

#define _COMPONENT          ACPI_NAMESPACE
ACPI_MODULE_NAME("nswalk")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_get_next_node
 *
 * PARAMETERS:  parent_node         - Parent node whose children we are
 *                                    getting
 *              child_node          - Previous child that was found.
 *                                    The NEXT child will be returned
 *
 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
 *                                    none is found.
 *
 * DESCRIPTION: Return the next peer node within the namespace.  If Handle
 *              is valid, Scope is ignored.  Otherwise, the first node
 *              within Scope is returned.
 *
 ******************************************************************************/
struct acpi_namespace_node *acpi_ns_get_next_node(struct acpi_namespace_node
                          *parent_node,
                          struct acpi_namespace_node
                          *child_node)
{
    ACPI_FUNCTION_ENTRY();

    if (!child_node) {

        /* It's really the parent's _scope_ that we want */

        return parent_node->child;
    }

    /* Otherwise just return the next peer */

    return child_node->peer;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_get_next_node_typed
 *
 * PARAMETERS:  type                - Type of node to be searched for
 *              parent_node         - Parent node whose children we are
 *                                    getting
 *              child_node          - Previous child that was found.
 *                                    The NEXT child will be returned
 *
 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
 *                                    none is found.
 *
 * DESCRIPTION: Return the next peer node within the namespace.  If Handle
 *              is valid, Scope is ignored.  Otherwise, the first node
 *              within Scope is returned.
 *
 ******************************************************************************/

struct acpi_namespace_node *acpi_ns_get_next_node_typed(acpi_object_type type,
                            struct
                            acpi_namespace_node
                            *parent_node,
                            struct
                            acpi_namespace_node
                            *child_node)
{
    struct acpi_namespace_node *next_node = NULL;

    ACPI_FUNCTION_ENTRY();

    next_node = acpi_ns_get_next_node(parent_node, child_node);


    /* If any type is OK, we are done */

    if (type == ACPI_TYPE_ANY) {

        /* next_node is NULL if we are at the end-of-list */

        return (next_node);
    }

    /* Must search for the node -- but within this scope only */

    while (next_node) {

        /* If type matches, we are done */

        if (next_node->type == type) {
            return (next_node);
        }

        /* Otherwise, move on to the next peer node */

        next_node = next_node->peer;
    }

    /* Not found */

    return (NULL);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_walk_namespace
 *
 * PARAMETERS:  type                - acpi_object_type to search for
 *              start_node          - Handle in namespace where search begins
 *              max_depth           - Depth to which search is to reach
 *              flags               - Whether to unlock the NS before invoking
 *                                    the callback routine
 *              pre_order_visit     - Called during tree pre-order visit
 *                                    when an object of "Type" is found
 *              post_order_visit    - Called during tree post-order visit
 *                                    when an object of "Type" is found
 *              context             - Passed to user function(s) above
 *              return_value        - from the user_function if terminated
 *                                    early. Otherwise, returns NULL.
 * RETURNS:     Status
 *
 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 *              starting (and ending) at the node specified by start_handle.
 *              The callback function is called whenever a node that matches
 *              the type parameter is found. If the callback function returns
 *              a non-zero value, the search is terminated immediately and
 *              this value is returned to the caller.
 *
 *              The point of this procedure is to provide a generic namespace
 *              walk routine that can be called from multiple places to
 *              provide multiple services; the callback function(s) can be
 *              tailored to each task, whether it is a print function,
 *              a compare function, etc.
 *
 ******************************************************************************/

acpi_status
acpi_ns_walk_namespace(acpi_object_type type,
               acpi_handle start_node,
               u32 max_depth,
               u32 flags,
               acpi_walk_callback pre_order_visit,
               acpi_walk_callback post_order_visit,
               void *context, void **return_value)
{
    acpi_status status;
    acpi_status mutex_status;
    struct acpi_namespace_node *child_node;
    struct acpi_namespace_node *parent_node;
    acpi_object_type child_type;
    u32 level;
    u8 node_previously_visited = FALSE;

    ACPI_FUNCTION_TRACE(ns_walk_namespace);

    /* Special case for the namespace Root Node */

    if (start_node == ACPI_ROOT_OBJECT) {
        start_node = acpi_gbl_root_node;
    }

    /* Null child means "get first node" */

    parent_node = start_node;
    child_node = acpi_ns_get_next_node(parent_node, NULL);
    child_type = ACPI_TYPE_ANY;
    level = 1;

    /*
     * Traverse the tree of nodes until we bubble back up to where we
     * started. When Level is zero, the loop is done because we have
     * bubbled up to (and passed) the original parent handle (start_entry)
     */
    while (level > 0 && child_node) {
        status = AE_OK;

        /* Found next child, get the type if we are not searching for ANY */

        if (type != ACPI_TYPE_ANY) {
            child_type = child_node->type;
        }

        /*
         * Ignore all temporary namespace nodes (created during control
         * method execution) unless told otherwise. These temporary nodes
         * can cause a race condition because they can be deleted during
         * the execution of the user function (if the namespace is
         * unlocked before invocation of the user function.) Only the
         * debugger namespace dump will examine the temporary nodes.
         */
        if ((child_node->flags & ANOBJ_TEMPORARY) &&
            !(flags & ACPI_NS_WALK_TEMP_NODES)) {
            status = AE_CTRL_DEPTH;
        }

        /* Type must match requested type */

        else if (child_type == type) {
            /*
             * Found a matching node, invoke the user callback function.
             * Unlock the namespace if flag is set.
             */
            if (flags & ACPI_NS_WALK_UNLOCK) {
                mutex_status =
                    acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
                if (ACPI_FAILURE(mutex_status)) {
                    return_ACPI_STATUS(mutex_status);
                }
            }

            /*
             * Invoke the user function, either pre-order or post-order
             * or both.
             */
            if (!node_previously_visited) {
                if (pre_order_visit) {
                    status =
                        pre_order_visit(child_node, level,
                                context,
                                return_value);
                }
            } else {
                if (post_order_visit) {
                    status =
                        post_order_visit(child_node, level,
                                 context,
                                 return_value);
                }
            }

            if (flags & ACPI_NS_WALK_UNLOCK) {
                mutex_status =
                    acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
                if (ACPI_FAILURE(mutex_status)) {
                    return_ACPI_STATUS(mutex_status);
                }
            }

            switch (status) {
            case AE_OK:
            case AE_CTRL_DEPTH:

                /* Just keep going */
                break;

            case AE_CTRL_TERMINATE:

                /* Exit now, with OK status */

                return_ACPI_STATUS(AE_OK);

            default:

                /* All others are valid exceptions */

                return_ACPI_STATUS(status);
            }
        }

        /*
         * Depth first search: Attempt to go down another level in the
         * namespace if we are allowed to.  Don't go any further if we have
         * reached the caller specified maximum depth or if the user
         * function has specified that the maximum depth has been reached.
         */
        if (!node_previously_visited &&
            (level < max_depth) && (status != AE_CTRL_DEPTH)) {
            if (child_node->child) {

                /* There is at least one child of this node, visit it */

                level++;
                parent_node = child_node;
                child_node =
                    acpi_ns_get_next_node(parent_node, NULL);
                continue;
            }
        }

        /* No more children, re-visit this node */

        if (!node_previously_visited) {
            node_previously_visited = TRUE;
            continue;
        }

        /* No more children, visit peers */

        child_node = acpi_ns_get_next_node(parent_node, child_node);
        if (child_node) {
            node_previously_visited = FALSE;
        }

        /* No peers, re-visit parent */

        else {
            /*
             * No more children of this node (acpi_ns_get_next_node failed), go
             * back upwards in the namespace tree to the node's parent.
             */
            level--;
            child_node = parent_node;
            parent_node = parent_node->parent;

            node_previously_visited = TRUE;
        }
    }

    /* Complete walk, not terminated by user function */

    return_ACPI_STATUS(AE_OK);
}