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  1. /**************************************************************************
  2.  *
  3.  * Copyright 2008-2009 VMware, Inc., Palo Alto, CA., USA
  4.  * All Rights Reserved.
  5.  *
  6.  * Permission is hereby granted, free of charge, to any person obtaining a
  7.  * copy of this software and associated documentation files (the
  8.  * "Software"), to deal in the Software without restriction, including
  9.  * without limitation the rights to use, copy, modify, merge, publish,
  10.  * distribute, sub license, and/or sell copies of the Software, and to
  11.  * permit persons to whom the Software is furnished to do so, subject to
  12.  * the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice (including the
  15.  * next paragraph) shall be included in all copies or substantial portions
  16.  * of the Software.
  17.  *
  18.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20.  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21.  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22.  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23.  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24.  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25.  *
  26.  **************************************************************************/
  27. /*
  28.  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  29.  */
  30.  
  31. #include <linux/mutex.h>
  32. #include <linux/slab.h>
  33. #include <linux/module.h>
  34. #include <linux/bug.h>
  35. #include <drm/drm_global.h>
  36.  
  37. struct drm_global_item {
  38.         struct mutex mutex;
  39.         void *object;
  40.         int refcount;
  41. };
  42.  
  43. static struct drm_global_item glob[DRM_GLOBAL_NUM];
  44.  
  45. void drm_global_init(void)
  46. {
  47.         int i;
  48.  
  49.         for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
  50.                 struct drm_global_item *item = &glob[i];
  51.                 mutex_init(&item->mutex);
  52.                 item->object = NULL;
  53.                 item->refcount = 0;
  54.         }
  55. }
  56.  
  57. void drm_global_release(void)
  58. {
  59.         int i;
  60.         for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
  61.                 struct drm_global_item *item = &glob[i];
  62.                 BUG_ON(item->object != NULL);
  63.                 BUG_ON(item->refcount != 0);
  64.         }
  65. }
  66.  
  67. int drm_global_item_ref(struct drm_global_reference *ref)
  68. {
  69.         int ret;
  70.         struct drm_global_item *item = &glob[ref->global_type];
  71.         void *object;
  72.  
  73.         mutex_lock(&item->mutex);
  74.         if (item->refcount == 0) {
  75.                 item->object = kzalloc(ref->size, GFP_KERNEL);
  76.                 if (unlikely(item->object == NULL)) {
  77.                         ret = -ENOMEM;
  78.                         goto out_err;
  79.                 }
  80.  
  81.                 ref->object = item->object;
  82.                 ret = ref->init(ref);
  83.                 if (unlikely(ret != 0))
  84.                         goto out_err;
  85.  
  86.         }
  87.         ++item->refcount;
  88.         ref->object = item->object;
  89.         object = item->object;
  90.         mutex_unlock(&item->mutex);
  91.         return 0;
  92. out_err:
  93.         mutex_unlock(&item->mutex);
  94.         item->object = NULL;
  95.         return ret;
  96. }
  97. EXPORT_SYMBOL(drm_global_item_ref);
  98.  
  99. void drm_global_item_unref(struct drm_global_reference *ref)
  100. {
  101.         struct drm_global_item *item = &glob[ref->global_type];
  102.  
  103.         mutex_lock(&item->mutex);
  104.         BUG_ON(item->refcount == 0);
  105.         BUG_ON(ref->object != item->object);
  106.         if (--item->refcount == 0) {
  107.                 ref->release(ref);
  108.                 item->object = NULL;
  109.         }
  110.         mutex_unlock(&item->mutex);
  111. }
  112. EXPORT_SYMBOL(drm_global_item_unref);
  113.  
  114.