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 
32 struct vgem_fence {
33 	struct dma_fence base;
34 	struct spinlock lock;
35 	struct timer_list timer;
36 };
37 
vgem_fence_get_driver_name(struct dma_fence * fence)38 static const char *vgem_fence_get_driver_name(struct dma_fence *fence)
39 {
40 	return "vgem";
41 }
42 
vgem_fence_get_timeline_name(struct dma_fence * fence)43 static const char *vgem_fence_get_timeline_name(struct dma_fence *fence)
44 {
45 	return "unbound";
46 }
47 
vgem_fence_release(struct dma_fence * base)48 static 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(&fence->timer);
53 	dma_fence_free(&fence->base);
54 }
55 
vgem_fence_value_str(struct dma_fence * fence,char * str,int size)56 static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
57 {
58 	snprintf(str, size, "%llu", fence->seqno);
59 }
60 
vgem_fence_timeline_value_str(struct dma_fence * fence,char * str,int size)61 static void vgem_fence_timeline_value_str(struct dma_fence *fence, char *str,
62 					  int size)
63 {
64 	snprintf(str, size, "%llu",
65 		 dma_fence_is_signaled(fence) ? fence->seqno : 0);
66 }
67 
68 static 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 
vgem_fence_timeout(struct timer_list * t)77 static 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->base);
82 }
83 
vgem_fence_create(struct vgem_file * vfile,unsigned int flags)84 static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
85 					   unsigned int flags)
86 {
87 	struct vgem_fence *fence;
88 
89 	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
90 	if (!fence)
91 		return NULL;
92 
93 	spin_lock_init(&fence->lock);
94 	dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
95 		       dma_fence_context_alloc(1), 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(&fence->timer, 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  */
vgem_fence_attach_ioctl(struct drm_device * dev,void * data,struct drm_file * file)125 int 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(file, arg->handle);
144 	if (!obj)
145 		return -ENOENT;
146 
147 	fence = vgem_fence_create(vfile, 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(arg->flags & VGEM_FENCE_WRITE);
156 	if (!dma_resv_test_signaled(resv, usage)) {
157 		ret = -EBUSY;
158 		goto err_fence;
159 	}
160 
161 	/* Expose the fence via the dma-buf */
162 	dma_resv_lock(resv, NULL);
163 	ret = dma_resv_reserve_fences(resv, 1);
164 	if (!ret)
165 		dma_resv_add_fence(resv, fence, arg->flags & VGEM_FENCE_WRITE ?
166 				   DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
167 	dma_resv_unlock(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, fence, 1, 0, GFP_KERNEL);
173 		mutex_unlock(&vfile->fence_mutex);
174 		if (ret > 0) {
175 			arg->out_fence = ret;
176 			ret = 0;
177 		}
178 	}
179 err_fence:
180 	if (ret) {
181 		dma_fence_signal(fence);
182 		dma_fence_put(fence);
183 	}
184 err:
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  */
vgem_fence_signal_ioctl(struct drm_device * dev,void * data,struct drm_file * file)205 int 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, arg->fence);
219 	mutex_unlock(&vfile->fence_mutex);
220 	if (!fence)
221 		return -ENOENT;
222 	if (IS_ERR(fence))
223 		return PTR_ERR(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 
vgem_fence_open(struct vgem_file * vfile)233 int vgem_fence_open(struct vgem_file *vfile)
234 {
235 	mutex_init(&vfile->fence_mutex);
236 	idr_init_base(&vfile->fence_idr, 1);
237 
238 	return 0;
239 }
240 
__vgem_fence_idr_fini(int id,void * p,void * data)241 static int __vgem_fence_idr_fini(int id, void *p, void *data)
242 {
243 	dma_fence_signal(p);
244 	dma_fence_put(p);
245 	return 0;
246 }
247 
vgem_fence_close(struct vgem_file * vfile)248 void vgem_fence_close(struct vgem_file *vfile)
249 {
250 	idr_for_each(&vfile->fence_idr, __vgem_fence_idr_fini, vfile);
251 	idr_destroy(&vfile->fence_idr);
252 }
253