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utcache.c

/******************************************************************************
 *
 * Module Name: utcache - local cache allocation routines
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2007, R. Byron Moore
 * 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>

#define _COMPONENT          ACPI_UTILITIES
ACPI_MODULE_NAME("utcache")
#ifdef ACPI_USE_LOCAL_CACHE
/*******************************************************************************
 *
 * FUNCTION:    acpi_os_create_cache
 *
 * PARAMETERS:  cache_name      - Ascii name for the cache
 *              object_size     - Size of each cached object
 *              max_depth       - Maximum depth of the cache (in objects)
 *              return_cache    - Where the new cache object is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Create a cache object
 *
 ******************************************************************************/
acpi_status
acpi_os_create_cache(char *cache_name,
                 u16 object_size,
                 u16 max_depth, struct acpi_memory_list ** return_cache)
{
      struct acpi_memory_list *cache;

      ACPI_FUNCTION_ENTRY();

      if (!cache_name || !return_cache || (object_size < 16)) {
            return (AE_BAD_PARAMETER);
      }

      /* Create the cache object */

      cache = acpi_os_allocate(sizeof(struct acpi_memory_list));
      if (!cache) {
            return (AE_NO_MEMORY);
      }

      /* Populate the cache object and return it */

      ACPI_MEMSET(cache, 0, sizeof(struct acpi_memory_list));
      cache->link_offset = 8;
      cache->list_name = cache_name;
      cache->object_size = object_size;
      cache->max_depth = max_depth;

      *return_cache = cache;
      return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_os_purge_cache
 *
 * PARAMETERS:  Cache           - Handle to cache object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Free all objects within the requested cache.
 *
 ******************************************************************************/

acpi_status acpi_os_purge_cache(struct acpi_memory_list * cache)
{
      char *next;

      ACPI_FUNCTION_ENTRY();

      if (!cache) {
            return (AE_BAD_PARAMETER);
      }

      /* Walk the list of objects in this cache */

      while (cache->list_head) {

            /* Delete and unlink one cached state object */

            next = *(ACPI_CAST_INDIRECT_PTR(char,
                                    &(((char *)cache->
                                       list_head)[cache->
                                                link_offset])));
            ACPI_FREE(cache->list_head);

            cache->list_head = next;
            cache->current_depth--;
      }

      return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_os_delete_cache
 *
 * PARAMETERS:  Cache           - Handle to cache object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Free all objects within the requested cache and delete the
 *              cache object.
 *
 ******************************************************************************/

acpi_status acpi_os_delete_cache(struct acpi_memory_list * cache)
{
      acpi_status status;

      ACPI_FUNCTION_ENTRY();

      /* Purge all objects in the cache */

      status = acpi_os_purge_cache(cache);
      if (ACPI_FAILURE(status)) {
            return (status);
      }

      /* Now we can delete the cache object */

      ACPI_FREE(cache);
      return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_os_release_object
 *
 * PARAMETERS:  Cache       - Handle to cache object
 *              Object      - The object to be released
 *
 * RETURN:      None
 *
 * DESCRIPTION: Release an object to the specified cache.  If cache is full,
 *              the object is deleted.
 *
 ******************************************************************************/

acpi_status
acpi_os_release_object(struct acpi_memory_list * cache, void *object)
{
      acpi_status status;

      ACPI_FUNCTION_ENTRY();

      if (!cache || !object) {
            return (AE_BAD_PARAMETER);
      }

      /* If cache is full, just free this object */

      if (cache->current_depth >= cache->max_depth) {
            ACPI_FREE(object);
            ACPI_MEM_TRACKING(cache->total_freed++);
      }

      /* Otherwise put this object back into the cache */

      else {
            status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
            if (ACPI_FAILURE(status)) {
                  return (status);
            }

            /* Mark the object as cached */

            ACPI_MEMSET(object, 0xCA, cache->object_size);
            ACPI_SET_DESCRIPTOR_TYPE(object, ACPI_DESC_TYPE_CACHED);

            /* Put the object at the head of the cache list */

            *(ACPI_CAST_INDIRECT_PTR(char,
                               &(((char *)object)[cache->
                                              link_offset]))) =
                cache->list_head;
            cache->list_head = object;
            cache->current_depth++;

            (void)acpi_ut_release_mutex(ACPI_MTX_CACHES);
      }

      return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_os_acquire_object
 *
 * PARAMETERS:  Cache           - Handle to cache object
 *
 * RETURN:      the acquired object.  NULL on error
 *
 * DESCRIPTION: Get an object from the specified cache.  If cache is empty,
 *              the object is allocated.
 *
 ******************************************************************************/

void *acpi_os_acquire_object(struct acpi_memory_list *cache)
{
      acpi_status status;
      void *object;

      ACPI_FUNCTION_NAME(os_acquire_object);

      if (!cache) {
            return (NULL);
      }

      status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
      if (ACPI_FAILURE(status)) {
            return (NULL);
      }

      ACPI_MEM_TRACKING(cache->requests++);

      /* Check the cache first */

      if (cache->list_head) {

            /* There is an object available, use it */

            object = cache->list_head;
            cache->list_head = *(ACPI_CAST_INDIRECT_PTR(char,
                                              &(((char *)
                                                 object)[cache->
                                                       link_offset])));

            cache->current_depth--;

            ACPI_MEM_TRACKING(cache->hits++);
            ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
                          "Object %p from %s cache\n", object,
                          cache->list_name));

            status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
            if (ACPI_FAILURE(status)) {
                  return (NULL);
            }

            /* Clear (zero) the previously used Object */

            ACPI_MEMSET(object, 0, cache->object_size);
      } else {
            /* The cache is empty, create a new object */

            ACPI_MEM_TRACKING(cache->total_allocated++);

#ifdef ACPI_DBG_TRACK_ALLOCATIONS
            if ((cache->total_allocated - cache->total_freed) >
                cache->max_occupied) {
                  cache->max_occupied =
                      cache->total_allocated - cache->total_freed;
            }
#endif

            /* Avoid deadlock with ACPI_ALLOCATE_ZEROED */

            status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
            if (ACPI_FAILURE(status)) {
                  return (NULL);
            }

            object = ACPI_ALLOCATE_ZEROED(cache->object_size);
            if (!object) {
                  return (NULL);
            }
      }

      return (object);
}
#endif                        /* ACPI_USE_LOCAL_CACHE */

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