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, int result)
  57 {
  58         if (result)
  59                 dma_fence_set_error(&fence->finished, result);
  60         dma_fence_signal(&fence->finished);
  61 }
  62
  63 static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
  64 {
  65         return "drm_sched";
  66 }
  67
  68 static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
  69 {
  70         struct drm_sched_fence *fence = to_drm_sched_fence(f);
  71         return (const char *)fence->sched->name;
  72 }
  73
  74 static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
  75 {
  76         struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
  77         struct drm_sched_fence *fence = to_drm_sched_fence(f);
  78
  79         if (!WARN_ON_ONCE(!fence))
  80                 kmem_cache_free(sched_fence_slab, fence);
  81 }
  82
  83 /**
  84  * drm_sched_fence_free - free up an uninitialized fence
  85  *
  86  * @fence: fence to free
  87  *
  88  * Free up the fence memory. Should only be used if drm_sched_fence_init()
  89  * has not been called yet.
  90  */
  91 void drm_sched_fence_free(struct drm_sched_fence *fence)
  92 {
  93         /* This function should not be called if the fence has been initialized. */
  94         if (!WARN_ON_ONCE(fence->sched))
  95                 kmem_cache_free(sched_fence_slab, fence);
  96 }
  97
  98 /**
  99  * drm_sched_fence_release_scheduled - callback that fence can be freed
 100  *
 101  * @f: fence
 102  *
 103  * This function is called when the reference count becomes zero.
 104  * It just RCU schedules freeing up the fence.
 105  */
 106 static void drm_sched_fence_release_scheduled(struct dma_fence *f)
 107 {
 108         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 109
 110         dma_fence_put(fence->parent);
 111         call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
 112 }
 113
 114 /**
 115  * drm_sched_fence_release_finished - drop extra reference
 116  *
 117  * @f: fence
 118  *
 119  * Drop the extra reference from the scheduled fence to the base fence.
 120  */
 121 static void drm_sched_fence_release_finished(struct dma_fence *f)
 122 {
 123         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 124
 125         dma_fence_put(&fence->scheduled);
 126 }
 127
 128 static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
 129                                                   ktime_t deadline)
 130 {
 131         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 132         struct dma_fence *parent;
 133         unsigned long flags;
 134
 135         spin_lock_irqsave(&fence->lock, flags);
 136
 137         /* If we already have an earlier deadline, keep it: */
 138         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
 139             ktime_before(fence->deadline, deadline)) {
 140                 spin_unlock_irqrestore(&fence->lock, flags);
 141                 return;
 142         }
 143
 144         fence->deadline = deadline;
 145         set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
 146
 147         spin_unlock_irqrestore(&fence->lock, flags);
 148
 149         /*
 150          * smp_load_aquire() to ensure that if we are racing another
 151          * thread calling drm_sched_fence_set_parent(), that we see
 152          * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
 153          */
 154         parent = smp_load_acquire(&fence->parent);
 155         if (parent)
 156                 dma_fence_set_deadline(parent, deadline);
 157 }
 158
 159 static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
 160         .get_driver_name = drm_sched_fence_get_driver_name,
 161         .get_timeline_name = drm_sched_fence_get_timeline_name,
 162         .release = drm_sched_fence_release_scheduled,
 163 };
 164
 165 static const struct dma_fence_ops drm_sched_fence_ops_finished = {
 166         .get_driver_name = drm_sched_fence_get_driver_name,
 167         .get_timeline_name = drm_sched_fence_get_timeline_name,
 168         .release = drm_sched_fence_release_finished,
 169         .set_deadline = drm_sched_fence_set_deadline_finished,
 170 };
 171
 172 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
 173 {
 174         if (f->ops == &drm_sched_fence_ops_scheduled)
 175                 return container_of(f, struct drm_sched_fence, scheduled);
 176
 177         if (f->ops == &drm_sched_fence_ops_finished)
 178                 return container_of(f, struct drm_sched_fence, finished);
 179
 180         return NULL;
 181 }
 182 EXPORT_SYMBOL(to_drm_sched_fence);
 183
 184 void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
 185                                 struct dma_fence *fence)
 186 {
 187         /*
 188          * smp_store_release() to ensure another thread racing us
 189          * in drm_sched_fence_set_deadline_finished() sees the
 190          * fence's parent set before test_bit()
 191          */
 192         smp_store_release(&s_fence->parent, dma_fence_get(fence));
 193         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
 194                      &s_fence->finished.flags))
 195                 dma_fence_set_deadline(fence, s_fence->deadline);
 196 }
 197
 198 struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
 199                                               void *owner)
 200 {
 201         struct drm_sched_fence *fence = NULL;
 202
 203         fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
 204         if (fence == NULL)
 205                 return NULL;
 206
 207         fence->owner = owner;
 208         spin_lock_init(&fence->lock);
 209
 210         return fence;
 211 }
 212
 213 void drm_sched_fence_init(struct drm_sched_fence *fence,
 214                           struct drm_sched_entity *entity)
 215 {
 216         unsigned seq;
 217
 218         fence->sched = entity->rq->sched;
 219         seq = atomic_inc_return(&entity->fence_seq);
 220         dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
 221                        &fence->lock, entity->fence_context, seq);
 222         dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
 223                        &fence->lock, entity->fence_context + 1, seq);
 224 }
 225
 226 module_init(drm_sched_fence_slab_init);
 227 module_exit(drm_sched_fence_slab_fini);
 228
 229 MODULE_DESCRIPTION("DRM GPU scheduler");
 230 MODULE_LICENSE("GPL and additional rights");