drivers/gpu/drm/vgem/vgem_fence.c

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