1/*
2 * Copyright 2016 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software")
6 * to deal in the software without restriction, including without limitation
7 * on the rights to use, copy, modify, merge, publish, distribute, sub
8 * license, and/or sell copies of the Software, and to permit persons to whom
9 * them Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTIBILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER
19 * IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN
20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21 */
22
23#include <linux/dma-buf.h>
24#include <linux/dma-resv.h>
25
26#include <drm/drm_file.h>
27
28#include "vgem_drv.h"
29
30#define VGEM_FENCE_TIMEOUT (10*HZ)
31
32struct vgem_fence {
33 struct dma_fence base;
34 struct spinlock lock;
35 struct timer_list timer;
36};
37
38static const char *vgem_fence_get_driver_name(struct dma_fence *fence)
39{
40 return "vgem";
41}
42
43static const char *vgem_fence_get_timeline_name(struct dma_fence *fence)
44{
45 return "unbound";
46}
47
48static void vgem_fence_release(struct dma_fence *base)
49{
50 struct vgem_fence *fence = container_of(base, typeof(*fence), base);
51
52 del_timer_sync(timer: &fence->timer);
53 dma_fence_free(fence: &fence->base);
54}
55
56static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
57{
58 snprintf(buf: str, size, fmt: "%llu", fence->seqno);
59}
60
61static void vgem_fence_timeline_value_str(struct dma_fence *fence, char *str,
62 int size)
63{
64 snprintf(buf: str, size, fmt: "%llu",
65 dma_fence_is_signaled(fence) ? fence->seqno : 0);
66}
67
68static const struct dma_fence_ops vgem_fence_ops = {
69 .get_driver_name = vgem_fence_get_driver_name,
70 .get_timeline_name = vgem_fence_get_timeline_name,
71 .release = vgem_fence_release,
72
73 .fence_value_str = vgem_fence_value_str,
74 .timeline_value_str = vgem_fence_timeline_value_str,
75};
76
77static void vgem_fence_timeout(struct timer_list *t)
78{
79 struct vgem_fence *fence = from_timer(fence, t, timer);
80
81 dma_fence_signal(fence: &fence->base);
82}
83
84static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
85 unsigned int flags)
86{
87 struct vgem_fence *fence;
88
89 fence = kzalloc(size: sizeof(*fence), GFP_KERNEL);
90 if (!fence)
91 return NULL;
92
93 spin_lock_init(&fence->lock);
94 dma_fence_init(fence: &fence->base, ops: &vgem_fence_ops, lock: &fence->lock,
95 context: dma_fence_context_alloc(num: 1), seqno: 1);
96
97 timer_setup(&fence->timer, vgem_fence_timeout, 0);
98
99 /* We force the fence to expire within 10s to prevent driver hangs */
100 mod_timer(timer: &fence->timer, expires: jiffies + VGEM_FENCE_TIMEOUT);
101
102 return &fence->base;
103}
104
105/*
106 * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH):
107 *
108 * Create and attach a fence to the vGEM handle. This fence is then exposed
109 * via the dma-buf reservation object and visible to consumers of the exported
110 * dma-buf. If the flags contain VGEM_FENCE_WRITE, the fence indicates the
111 * vGEM buffer is being written to by the client and is exposed as an exclusive
112 * fence, otherwise the fence indicates the client is current reading from the
113 * buffer and all future writes should wait for the client to signal its
114 * completion. Note that if a conflicting fence is already on the dma-buf (i.e.
115 * an exclusive fence when adding a read, or any fence when adding a write),
116 * -EBUSY is reported. Serialisation between operations should be handled
117 * by waiting upon the dma-buf.
118 *
119 * This returns the handle for the new fence that must be signaled within 10
120 * seconds (or otherwise it will automatically expire). See
121 * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL).
122 *
123 * If the vGEM handle does not exist, vgem_fence_attach_ioctl returns -ENOENT.
124 */
125int vgem_fence_attach_ioctl(struct drm_device *dev,
126 void *data,
127 struct drm_file *file)
128{
129 struct drm_vgem_fence_attach *arg = data;
130 struct vgem_file *vfile = file->driver_priv;
131 struct dma_resv *resv;
132 struct drm_gem_object *obj;
133 enum dma_resv_usage usage;
134 struct dma_fence *fence;
135 int ret;
136
137 if (arg->flags & ~VGEM_FENCE_WRITE)
138 return -EINVAL;
139
140 if (arg->pad)
141 return -EINVAL;
142
143 obj = drm_gem_object_lookup(filp: file, handle: arg->handle);
144 if (!obj)
145 return -ENOENT;
146
147 fence = vgem_fence_create(vfile, flags: arg->flags);
148 if (!fence) {
149 ret = -ENOMEM;
150 goto err;
151 }
152
153 /* Check for a conflicting fence */
154 resv = obj->resv;
155 usage = dma_resv_usage_rw(write: arg->flags & VGEM_FENCE_WRITE);
156 if (!dma_resv_test_signaled(obj: resv, usage)) {
157 ret = -EBUSY;
158 goto err_fence;
159 }
160
161 /* Expose the fence via the dma-buf */
162 dma_resv_lock(obj: resv, NULL);
163 ret = dma_resv_reserve_fences(obj: resv, num_fences: 1);
164 if (!ret)
165 dma_resv_add_fence(obj: resv, fence, usage: arg->flags & VGEM_FENCE_WRITE ?
166 DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
167 dma_resv_unlock(obj: resv);
168
169 /* Record the fence in our idr for later signaling */
170 if (ret == 0) {
171 mutex_lock(&vfile->fence_mutex);
172 ret = idr_alloc(&vfile->fence_idr, ptr: fence, start: 1, end: 0, GFP_KERNEL);
173 mutex_unlock(lock: &vfile->fence_mutex);
174 if (ret > 0) {
175 arg->out_fence = ret;
176 ret = 0;
177 }
178 }
179err_fence:
180 if (ret) {
181 dma_fence_signal(fence);
182 dma_fence_put(fence);
183 }
184err:
185 drm_gem_object_put(obj);
186 return ret;
187}
188
189/*
190 * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL):
191 *
192 * Signal and consume a fence ealier attached to a vGEM handle using
193 * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH).
194 *
195 * All fences must be signaled within 10s of attachment or otherwise they
196 * will automatically expire (and a vgem_fence_signal_ioctl returns -ETIMEDOUT).
197 *
198 * Signaling a fence indicates to all consumers of the dma-buf that the
199 * client has completed the operation associated with the fence, and that the
200 * buffer is then ready for consumption.
201 *
202 * If the fence does not exist (or has already been signaled by the client),
203 * vgem_fence_signal_ioctl returns -ENOENT.
204 */
205int vgem_fence_signal_ioctl(struct drm_device *dev,
206 void *data,
207 struct drm_file *file)
208{
209 struct vgem_file *vfile = file->driver_priv;
210 struct drm_vgem_fence_signal *arg = data;
211 struct dma_fence *fence;
212 int ret = 0;
213
214 if (arg->flags)
215 return -EINVAL;
216
217 mutex_lock(&vfile->fence_mutex);
218 fence = idr_replace(&vfile->fence_idr, NULL, id: arg->fence);
219 mutex_unlock(lock: &vfile->fence_mutex);
220 if (!fence)
221 return -ENOENT;
222 if (IS_ERR(ptr: fence))
223 return PTR_ERR(ptr: fence);
224
225 if (dma_fence_is_signaled(fence))
226 ret = -ETIMEDOUT;
227
228 dma_fence_signal(fence);
229 dma_fence_put(fence);
230 return ret;
231}
232
233int vgem_fence_open(struct vgem_file *vfile)
234{
235 mutex_init(&vfile->fence_mutex);
236 idr_init_base(idr: &vfile->fence_idr, base: 1);
237
238 return 0;
239}
240
241static int __vgem_fence_idr_fini(int id, void *p, void *data)
242{
243 dma_fence_signal(fence: p);
244 dma_fence_put(fence: p);
245 return 0;
246}
247
248void vgem_fence_close(struct vgem_file *vfile)
249{
250 idr_for_each(&vfile->fence_idr, fn: __vgem_fence_idr_fini, data: vfile);
251 idr_destroy(&vfile->fence_idr);
252 mutex_destroy(lock: &vfile->fence_mutex);
253}
254

source code of linux/drivers/gpu/drm/vgem/vgem_fence.c