drivers/gpu/drm/scheduler/sched_fence.c

   1 /*
   2  * Copyright 2015 Advanced Micro Devices, Inc.
   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  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  */
  23
  24 #include <linux/kthread.h>
  25 #include <linux/module.h>
  26 #include <linux/sched.h>
  27 #include <linux/slab.h>
  28 #include <linux/wait.h>
  29
  30 #include <drm/gpu_scheduler.h>
  31
  32 static struct kmem_cache *sched_fence_slab;
  33
  34 static int __init drm_sched_fence_slab_init(void)
  35 {
  36         sched_fence_slab = kmem_cache_create(
  37                 "drm_sched_fence", sizeof(struct drm_sched_fence), 0,
  38                 SLAB_HWCACHE_ALIGN, NULL);
  39         if (!sched_fence_slab)
  40                 return -ENOMEM;
  41
  42         return 0;
  43 }
  44
  45 static void __exit drm_sched_fence_slab_fini(void)
  46 {
  47         rcu_barrier();
  48         kmem_cache_destroy(sched_fence_slab);
  49 }
  50
  51 void drm_sched_fence_scheduled(struct drm_sched_fence *fence)
  52 {
  53         dma_fence_signal(&fence->scheduled);
  54 }
  55
  56 void drm_sched_fence_finished(struct drm_sched_fence *fence)
  57 {
  58         dma_fence_signal(&fence->finished);
  59 }
  60
  61 static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
  62 {
  63         return "drm_sched";
  64 }
  65
  66 static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
  67 {
  68         struct drm_sched_fence *fence = to_drm_sched_fence(f);
  69         return (const char *)fence->sched->name;
  70 }
  71
  72 static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
  73 {
  74         struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
  75         struct drm_sched_fence *fence = to_drm_sched_fence(f);
  76
  77         if (!WARN_ON_ONCE(!fence))
  78                 kmem_cache_free(sched_fence_slab, fence);
  79 }
  80
  81 /**
  82  * drm_sched_fence_free - free up an uninitialized fence
  83  *
  84  * @fence: fence to free
  85  *
  86  * Free up the fence memory. Should only be used if drm_sched_fence_init()
  87  * has not been called yet.
  88  */
  89 void drm_sched_fence_free(struct drm_sched_fence *fence)
  90 {
  91         /* This function should not be called if the fence has been initialized. */
  92         if (!WARN_ON_ONCE(fence->sched))
  93                 kmem_cache_free(sched_fence_slab, fence);
  94 }
  95
  96 /**
  97  * drm_sched_fence_release_scheduled - callback that fence can be freed
  98  *
  99  * @f: fence
 100  *
 101  * This function is called when the reference count becomes zero.
 102  * It just RCU schedules freeing up the fence.
 103  */
 104 static void drm_sched_fence_release_scheduled(struct dma_fence *f)
 105 {
 106         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 107
 108         dma_fence_put(fence->parent);
 109         call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
 110 }
 111
 112 /**
 113  * drm_sched_fence_release_finished - drop extra reference
 114  *
 115  * @f: fence
 116  *
 117  * Drop the extra reference from the scheduled fence to the base fence.
 118  */
 119 static void drm_sched_fence_release_finished(struct dma_fence *f)
 120 {
 121         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 122
 123         dma_fence_put(&fence->scheduled);
 124 }
 125
 126 static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
 127                                                   ktime_t deadline)
 128 {
 129         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 130         struct dma_fence *parent;
 131         unsigned long flags;
 132
 133         spin_lock_irqsave(&fence->lock, flags);
 134
 135         /* If we already have an earlier deadline, keep it: */
 136         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
 137             ktime_before(fence->deadline, deadline)) {
 138                 spin_unlock_irqrestore(&fence->lock, flags);
 139                 return;
 140         }
 141
 142         fence->deadline = deadline;
 143         set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
 144
 145         spin_unlock_irqrestore(&fence->lock, flags);
 146
 147         /*
 148          * smp_load_aquire() to ensure that if we are racing another
 149          * thread calling drm_sched_fence_set_parent(), that we see
 150          * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
 151          */
 152         parent = smp_load_acquire(&fence->parent);
 153         if (parent)
 154                 dma_fence_set_deadline(parent, deadline);
 155 }
 156
 157 static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
 158         .get_driver_name = drm_sched_fence_get_driver_name,
 159         .get_timeline_name = drm_sched_fence_get_timeline_name,
 160         .release = drm_sched_fence_release_scheduled,
 161 };
 162
 163 static const struct dma_fence_ops drm_sched_fence_ops_finished = {
 164         .get_driver_name = drm_sched_fence_get_driver_name,
 165         .get_timeline_name = drm_sched_fence_get_timeline_name,
 166         .release = drm_sched_fence_release_finished,
 167         .set_deadline = drm_sched_fence_set_deadline_finished,
 168 };
 169
 170 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
 171 {
 172         if (f->ops == &drm_sched_fence_ops_scheduled)
 173                 return container_of(f, struct drm_sched_fence, scheduled);
 174
 175         if (f->ops == &drm_sched_fence_ops_finished)
 176                 return container_of(f, struct drm_sched_fence, finished);
 177
 178         return NULL;
 179 }
 180 EXPORT_SYMBOL(to_drm_sched_fence);
 181
 182 void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
 183                                 struct dma_fence *fence)
 184 {
 185         /*
 186          * smp_store_release() to ensure another thread racing us
 187          * in drm_sched_fence_set_deadline_finished() sees the
 188          * fence's parent set before test_bit()
 189          */
 190         smp_store_release(&s_fence->parent, dma_fence_get(fence));
 191         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
 192                      &s_fence->finished.flags))
 193                 dma_fence_set_deadline(fence, s_fence->deadline);
 194 }
 195
 196 struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
 197                                               void *owner)
 198 {
 199         struct drm_sched_fence *fence = NULL;
 200
 201         fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
 202         if (fence == NULL)
 203                 return NULL;
 204
 205         fence->owner = owner;
 206         spin_lock_init(&fence->lock);
 207
 208         return fence;
 209 }
 210
 211 void drm_sched_fence_init(struct drm_sched_fence *fence,
 212                           struct drm_sched_entity *entity)
 213 {
 214         unsigned seq;
 215
 216         fence->sched = entity->rq->sched;
 217         seq = atomic_inc_return(&entity->fence_seq);
 218         dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
 219                        &fence->lock, entity->fence_context, seq);
 220         dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
 221                        &fence->lock, entity->fence_context + 1, seq);
 222 }
 223
 224 module_init(drm_sched_fence_slab_init);
 225 module_exit(drm_sched_fence_slab_fini);
 226
 227 MODULE_DESCRIPTION("DRM GPU scheduler");
 228 MODULE_LICENSE("GPL and additional rights");