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/reservation.h>
 25
 26#include "vgem_drv.h"
 27
 28#define VGEM_FENCE_TIMEOUT (10*HZ)
 29
 30struct vgem_fence {
 31	struct dma_fence base;
 32	struct spinlock lock;
 33	struct timer_list timer;
 34};
 35
 36static const char *vgem_fence_get_driver_name(struct dma_fence *fence)
 37{
 38	return "vgem";
 39}
 40
 41static const char *vgem_fence_get_timeline_name(struct dma_fence *fence)
 42{
 43	return "unbound";
 44}
 45
 46static bool vgem_fence_signaled(struct dma_fence *fence)
 47{
 48	return false;
 49}
 50
 51static bool vgem_fence_enable_signaling(struct dma_fence *fence)
 52{
 53	return true;
 54}
 55
 56static void vgem_fence_release(struct dma_fence *base)
 57{
 58	struct vgem_fence *fence = container_of(base, typeof(*fence), base);
 59
 60	del_timer_sync(&fence->timer);
 61	dma_fence_free(&fence->base);
 62}
 63
 64static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
 65{
 66	snprintf(str, size, "%u", fence->seqno);
 67}
 68
 69static void vgem_fence_timeline_value_str(struct dma_fence *fence, char *str,
 70					  int size)
 71{
 72	snprintf(str, size, "%u",
 73		 dma_fence_is_signaled(fence) ? fence->seqno : 0);
 74}
 75
 76static const struct dma_fence_ops vgem_fence_ops = {
 77	.get_driver_name = vgem_fence_get_driver_name,
 78	.get_timeline_name = vgem_fence_get_timeline_name,
 79	.enable_signaling = vgem_fence_enable_signaling,
 80	.signaled = vgem_fence_signaled,
 81	.wait = dma_fence_default_wait,
 82	.release = vgem_fence_release,
 83
 84	.fence_value_str = vgem_fence_value_str,
 85	.timeline_value_str = vgem_fence_timeline_value_str,
 86};
 87
 88static void vgem_fence_timeout(struct timer_list *t)
 89{
 90	struct vgem_fence *fence = from_timer(fence, t, timer);
 91
 92	dma_fence_signal(&fence->base);
 93}
 94
 95static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
 96					   unsigned int flags)
 97{
 98	struct vgem_fence *fence;
 99
100	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
101	if (!fence)
102		return NULL;
103
104	spin_lock_init(&fence->lock);
105	dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
106		       dma_fence_context_alloc(1), 1);
107
108	timer_setup(&fence->timer, vgem_fence_timeout, 0);
109
110	/* We force the fence to expire within 10s to prevent driver hangs */
111	mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
112
113	return &fence->base;
114}
115
116static int attach_dmabuf(struct drm_device *dev,
117			 struct drm_gem_object *obj)
118{
119	struct dma_buf *dmabuf;
120
121	if (obj->dma_buf)
122		return 0;
123
124	dmabuf = dev->driver->gem_prime_export(dev, obj, 0);
125	if (IS_ERR(dmabuf))
126		return PTR_ERR(dmabuf);
127
128	obj->dma_buf = dmabuf;
129	return 0;
130}
131
132/*
133 * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH):
134 *
135 * Create and attach a fence to the vGEM handle. This fence is then exposed
136 * via the dma-buf reservation object and visible to consumers of the exported
137 * dma-buf. If the flags contain VGEM_FENCE_WRITE, the fence indicates the
138 * vGEM buffer is being written to by the client and is exposed as an exclusive
139 * fence, otherwise the fence indicates the client is current reading from the
140 * buffer and all future writes should wait for the client to signal its
141 * completion. Note that if a conflicting fence is already on the dma-buf (i.e.
142 * an exclusive fence when adding a read, or any fence when adding a write),
143 * -EBUSY is reported. Serialisation between operations should be handled
144 * by waiting upon the dma-buf.
145 *
146 * This returns the handle for the new fence that must be signaled within 10
147 * seconds (or otherwise it will automatically expire). See
148 * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL).
149 *
150 * If the vGEM handle does not exist, vgem_fence_attach_ioctl returns -ENOENT.
151 */
152int vgem_fence_attach_ioctl(struct drm_device *dev,
153			    void *data,
154			    struct drm_file *file)
155{
156	struct drm_vgem_fence_attach *arg = data;
157	struct vgem_file *vfile = file->driver_priv;
158	struct reservation_object *resv;
159	struct drm_gem_object *obj;
160	struct dma_fence *fence;
161	int ret;
162
163	if (arg->flags & ~VGEM_FENCE_WRITE)
164		return -EINVAL;
165
166	if (arg->pad)
167		return -EINVAL;
168
169	obj = drm_gem_object_lookup(file, arg->handle);
170	if (!obj)
171		return -ENOENT;
172
173	ret = attach_dmabuf(dev, obj);
174	if (ret)
175		goto err;
176
177	fence = vgem_fence_create(vfile, arg->flags);
178	if (!fence) {
179		ret = -ENOMEM;
180		goto err;
181	}
182
183	/* Check for a conflicting fence */
184	resv = obj->dma_buf->resv;
185	if (!reservation_object_test_signaled_rcu(resv,
186						  arg->flags & VGEM_FENCE_WRITE)) {
187		ret = -EBUSY;
188		goto err_fence;
189	}
190
191	/* Expose the fence via the dma-buf */
192	ret = 0;
193	reservation_object_lock(resv, NULL);
194	if (arg->flags & VGEM_FENCE_WRITE)
195		reservation_object_add_excl_fence(resv, fence);
196	else if ((ret = reservation_object_reserve_shared(resv)) == 0)
197		reservation_object_add_shared_fence(resv, fence);
198	reservation_object_unlock(resv);
199
200	/* Record the fence in our idr for later signaling */
201	if (ret == 0) {
202		mutex_lock(&vfile->fence_mutex);
203		ret = idr_alloc(&vfile->fence_idr, fence, 1, 0, GFP_KERNEL);
204		mutex_unlock(&vfile->fence_mutex);
205		if (ret > 0) {
206			arg->out_fence = ret;
207			ret = 0;
208		}
209	}
210err_fence:
211	if (ret) {
212		dma_fence_signal(fence);
213		dma_fence_put(fence);
214	}
215err:
216	drm_gem_object_put_unlocked(obj);
217	return ret;
218}
219
220/*
221 * vgem_fence_signal_ioctl (DRM_IOCTL_VGEM_FENCE_SIGNAL):
222 *
223 * Signal and consume a fence ealier attached to a vGEM handle using
224 * vgem_fence_attach_ioctl (DRM_IOCTL_VGEM_FENCE_ATTACH).
225 *
226 * All fences must be signaled within 10s of attachment or otherwise they
227 * will automatically expire (and a vgem_fence_signal_ioctl returns -ETIMEDOUT).
228 *
229 * Signaling a fence indicates to all consumers of the dma-buf that the
230 * client has completed the operation associated with the fence, and that the
231 * buffer is then ready for consumption.
232 *
233 * If the fence does not exist (or has already been signaled by the client),
234 * vgem_fence_signal_ioctl returns -ENOENT.
235 */
236int vgem_fence_signal_ioctl(struct drm_device *dev,
237			    void *data,
238			    struct drm_file *file)
239{
240	struct vgem_file *vfile = file->driver_priv;
241	struct drm_vgem_fence_signal *arg = data;
242	struct dma_fence *fence;
243	int ret = 0;
244
245	if (arg->flags)
246		return -EINVAL;
247
248	mutex_lock(&vfile->fence_mutex);
249	fence = idr_replace(&vfile->fence_idr, NULL, arg->fence);
250	mutex_unlock(&vfile->fence_mutex);
251	if (!fence)
252		return -ENOENT;
253	if (IS_ERR(fence))
254		return PTR_ERR(fence);
255
256	if (dma_fence_is_signaled(fence))
257		ret = -ETIMEDOUT;
258
259	dma_fence_signal(fence);
260	dma_fence_put(fence);
261	return ret;
262}
263
264int vgem_fence_open(struct vgem_file *vfile)
265{
266	mutex_init(&vfile->fence_mutex);
267	idr_init(&vfile->fence_idr);
268
269	return 0;
270}
271
272static int __vgem_fence_idr_fini(int id, void *p, void *data)
273{
274	dma_fence_signal(p);
275	dma_fence_put(p);
276	return 0;
277}
278
279void vgem_fence_close(struct vgem_file *vfile)
280{
281	idr_for_each(&vfile->fence_idr, __vgem_fence_idr_fini, vfile);
282	idr_destroy(&vfile->fence_idr);
283}