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 <drm/drmP.h> 32 #include <linux/mutex.h> 33 #include <linux/slab.h> 34 #include <linux/module.h> 35 #include <drm/drm_global.h> 36 37 struct drm_global_item { 38 struct lock 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 lockinit(&item->mutex, "drmgi", 0, LK_CANRECURSE); 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 /** 68 * drm_global_item_ref - Initialize and acquire reference to memory 69 * object 70 * @ref: Object for initialization 71 * 72 * This initializes a memory object, allocating memory and calling the 73 * .init() hook. Further calls will increase the reference count for 74 * that item. 75 * 76 * Returns: 77 * Zero on success, non-zero otherwise. 78 */ 79 int drm_global_item_ref(struct drm_global_reference *ref) 80 { 81 int ret = 0; 82 struct drm_global_item *item = &glob[ref->global_type]; 83 84 mutex_lock(&item->mutex); 85 if (item->refcount == 0) { 86 ref->object = kzalloc(ref->size, GFP_KERNEL); 87 if (unlikely(ref->object == NULL)) { 88 ret = -ENOMEM; 89 goto error_unlock; 90 } 91 ret = ref->init(ref); 92 if (unlikely(ret != 0)) 93 goto error_free; 94 95 item->object = ref->object; 96 } else { 97 ref->object = item->object; 98 } 99 100 ++item->refcount; 101 mutex_unlock(&item->mutex); 102 return 0; 103 104 error_free: 105 kfree(ref->object); 106 ref->object = NULL; 107 error_unlock: 108 mutex_unlock(&item->mutex); 109 return ret; 110 } 111 EXPORT_SYMBOL(drm_global_item_ref); 112 113 /** 114 * drm_global_item_unref - Drop reference to memory 115 * object 116 * @ref: Object being removed 117 * 118 * Drop a reference to the memory object and eventually call the 119 * release() hook. The allocated object should be dropped in the 120 * release() hook or before calling this function 121 * 122 */ 123 124 void drm_global_item_unref(struct drm_global_reference *ref) 125 { 126 struct drm_global_item *item = &glob[ref->global_type]; 127 128 mutex_lock(&item->mutex); 129 BUG_ON(item->refcount == 0); 130 BUG_ON(ref->object != item->object); 131 if (--item->refcount == 0) { 132 ref->release(ref); 133 item->object = NULL; 134 } 135 mutex_unlock(&item->mutex); 136 } 137 EXPORT_SYMBOL(drm_global_item_unref); 138 139