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 bool vgem_fence_signaled(struct dma_fence *fence)
  47 {
  48         return false;
  49 }
  50
  51 static bool vgem_fence_enable_signaling(struct dma_fence *fence)
  52 {
  53         return true;
  54 }
  55
  56 static 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
  64 static void vgem_fence_value_str(struct dma_fence *fence, char *str, int size)
  65 {
  66         snprintf(str, size, "%u", fence->seqno);
  67 }
  68
  69 static 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
  76 static 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
  88 static void vgem_fence_timeout(unsigned long data)
  89 {
  90         struct vgem_fence *fence = (struct vgem_fence *)data;
  91
  92         dma_fence_signal(&fence->base);
  93 }
  94
  95 static 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         setup_timer(&fence->timer, vgem_fence_timeout, (unsigned long)fence);
 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
 116 static 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  */
 152 int 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         ww_mutex_lock(&resv->lock, 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         ww_mutex_unlock(&resv->lock);
 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         }
 210 err_fence:
 211         if (ret) {
 212                 dma_fence_signal(fence);
 213                 dma_fence_put(fence);
 214         }
 215 err:
 216         drm_gem_object_unreference_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  */
 236 int 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
 264 int 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
 272 static 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
 279 void 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 }