Root/drivers/gpu/drm/drm_global.c

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 "drm_global.h"
35
36struct drm_global_item {
37    struct mutex mutex;
38    void *object;
39    int refcount;
40};
41
42static struct drm_global_item glob[DRM_GLOBAL_NUM];
43
44void drm_global_init(void)
45{
46    int i;
47
48    for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
49        struct drm_global_item *item = &glob[i];
50        mutex_init(&item->mutex);
51        item->object = NULL;
52        item->refcount = 0;
53    }
54}
55
56void drm_global_release(void)
57{
58    int i;
59    for (i = 0; i < DRM_GLOBAL_NUM; ++i) {
60        struct drm_global_item *item = &glob[i];
61        BUG_ON(item->object != NULL);
62        BUG_ON(item->refcount != 0);
63    }
64}
65
66int drm_global_item_ref(struct drm_global_reference *ref)
67{
68    int ret;
69    struct drm_global_item *item = &glob[ref->global_type];
70    void *object;
71
72    mutex_lock(&item->mutex);
73    if (item->refcount == 0) {
74        item->object = kzalloc(ref->size, GFP_KERNEL);
75        if (unlikely(item->object == NULL)) {
76            ret = -ENOMEM;
77            goto out_err;
78        }
79
80        ref->object = item->object;
81        ret = ref->init(ref);
82        if (unlikely(ret != 0))
83            goto out_err;
84
85    }
86    ++item->refcount;
87    ref->object = item->object;
88    object = item->object;
89    mutex_unlock(&item->mutex);
90    return 0;
91out_err:
92    mutex_unlock(&item->mutex);
93    item->object = NULL;
94    return ret;
95}
96EXPORT_SYMBOL(drm_global_item_ref);
97
98void drm_global_item_unref(struct drm_global_reference *ref)
99{
100    struct drm_global_item *item = &glob[ref->global_type];
101
102    mutex_lock(&item->mutex);
103    BUG_ON(item->refcount == 0);
104    BUG_ON(ref->object != item->object);
105    if (--item->refcount == 0) {
106        ref->release(ref);
107        item->object = NULL;
108    }
109    mutex_unlock(&item->mutex);
110}
111EXPORT_SYMBOL(drm_global_item_unref);
112
113

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