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(&fence->timer);
 53	dma_fence_free(&fence->base);
 54}
 55
 56static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
 57{
 58	snprintf(str, size, "%llu", fence->seqno);
 59}
 60
 61static 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
 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->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(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 */
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	struct dma_fence *fence;
134	int ret;
135
136	if (arg->flags & ~VGEM_FENCE_WRITE)
137		return -EINVAL;
138
139	if (arg->pad)
140		return -EINVAL;
141
142	obj = drm_gem_object_lookup(file, arg->handle);
143	if (!obj)
144		return -ENOENT;
145
146	fence = vgem_fence_create(vfile, arg->flags);
147	if (!fence) {
148		ret = -ENOMEM;
149		goto err;
150	}
151
152	/* Check for a conflicting fence */
153	resv = obj->resv;
154	if (!dma_resv_test_signaled_rcu(resv,
155						  arg->flags & VGEM_FENCE_WRITE)) {
156		ret = -EBUSY;
157		goto err_fence;
158	}
159
160	/* Expose the fence via the dma-buf */
161	ret = 0;
162	dma_resv_lock(resv, NULL);
163	if (arg->flags & VGEM_FENCE_WRITE)
164		dma_resv_add_excl_fence(resv, fence);
165	else if ((ret = dma_resv_reserve_shared(resv, 1)) == 0)
166		dma_resv_add_shared_fence(resv, fence);
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	}
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, 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
233int vgem_fence_open(struct vgem_file *vfile)
234{
235	mutex_init(&vfile->fence_mutex);
236	idr_init(&vfile->fence_idr);
237
238	return 0;
239}
240
241static 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
248void 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}