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(drm_sched_fence, SLAB_HWCACHE_ALIGN);
  37         if (!sched_fence_slab)
  38                 return -ENOMEM;
  39
  40         return 0;
  41 }
  42
  43 static void __exit drm_sched_fence_slab_fini(void)
  44 {
  45         rcu_barrier();
  46         kmem_cache_destroy(sched_fence_slab);
  47 }
  48
  49 static void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
  50                                        struct dma_fence *fence)
  51 {
  52         /*
  53          * smp_store_release() to ensure another thread racing us
  54          * in drm_sched_fence_set_deadline_finished() sees the
  55          * fence's parent set before test_bit()
  56          */
  57         smp_store_release(&s_fence->parent, dma_fence_get(fence));
  58         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
  59                      &s_fence->finished.flags))
  60                 dma_fence_set_deadline(fence, s_fence->deadline);
  61 }
  62
  63 void drm_sched_fence_scheduled(struct drm_sched_fence *fence,
  64                                struct dma_fence *parent)
  65 {
  66         /* Set the parent before signaling the scheduled fence, such that,
  67          * any waiter expecting the parent to be filled after the job has
  68          * been scheduled (which is the case for drivers delegating waits
  69          * to some firmware) doesn't have to busy wait for parent to show
  70          * up.
  71          */
  72         if (!IS_ERR_OR_NULL(parent))
  73                 drm_sched_fence_set_parent(fence, parent);
  74
  75         dma_fence_signal(&fence->scheduled);
  76 }
  77
  78 void drm_sched_fence_finished(struct drm_sched_fence *fence, int result)
  79 {
  80         if (result)
  81                 dma_fence_set_error(&fence->finished, result);
  82         dma_fence_signal(&fence->finished);
  83 }
  84
  85 static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
  86 {
  87         return "drm_sched";
  88 }
  89
  90 static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
  91 {
  92         struct drm_sched_fence *fence = to_drm_sched_fence(f);
  93         return (const char *)fence->sched->name;
  94 }
  95
  96 static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
  97 {
  98         struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
  99         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 100
 101         if (!WARN_ON_ONCE(!fence))
 102                 kmem_cache_free(sched_fence_slab, fence);
 103 }
 104
 105 /**
 106  * drm_sched_fence_free - free up an uninitialized fence
 107  *
 108  * @fence: fence to free
 109  *
 110  * Free up the fence memory. Should only be used if drm_sched_fence_init()
 111  * has not been called yet.
 112  */
 113 void drm_sched_fence_free(struct drm_sched_fence *fence)
 114 {
 115         /* This function should not be called if the fence has been initialized. */
 116         if (!WARN_ON_ONCE(fence->sched))
 117                 kmem_cache_free(sched_fence_slab, fence);
 118 }
 119
 120 /**
 121  * drm_sched_fence_release_scheduled - callback that fence can be freed
 122  *
 123  * @f: fence
 124  *
 125  * This function is called when the reference count becomes zero.
 126  * It just RCU schedules freeing up the fence.
 127  */
 128 static void drm_sched_fence_release_scheduled(struct dma_fence *f)
 129 {
 130         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 131
 132         dma_fence_put(fence->parent);
 133         call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
 134 }
 135
 136 /**
 137  * drm_sched_fence_release_finished - drop extra reference
 138  *
 139  * @f: fence
 140  *
 141  * Drop the extra reference from the scheduled fence to the base fence.
 142  */
 143 static void drm_sched_fence_release_finished(struct dma_fence *f)
 144 {
 145         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 146
 147         dma_fence_put(&fence->scheduled);
 148 }
 149
 150 static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
 151                                                   ktime_t deadline)
 152 {
 153         struct drm_sched_fence *fence = to_drm_sched_fence(f);
 154         struct dma_fence *parent;
 155         unsigned long flags;
 156
 157         spin_lock_irqsave(&fence->lock, flags);
 158
 159         /* If we already have an earlier deadline, keep it: */
 160         if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
 161             ktime_before(fence->deadline, deadline)) {
 162                 spin_unlock_irqrestore(&fence->lock, flags);
 163                 return;
 164         }
 165
 166         fence->deadline = deadline;
 167         set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
 168
 169         spin_unlock_irqrestore(&fence->lock, flags);
 170
 171         /*
 172          * smp_load_aquire() to ensure that if we are racing another
 173          * thread calling drm_sched_fence_set_parent(), that we see
 174          * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
 175          */
 176         parent = smp_load_acquire(&fence->parent);
 177         if (parent)
 178                 dma_fence_set_deadline(parent, deadline);
 179 }
 180
 181 static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
 182         .get_driver_name = drm_sched_fence_get_driver_name,
 183         .get_timeline_name = drm_sched_fence_get_timeline_name,
 184         .release = drm_sched_fence_release_scheduled,
 185 };
 186
 187 static const struct dma_fence_ops drm_sched_fence_ops_finished = {
 188         .get_driver_name = drm_sched_fence_get_driver_name,
 189         .get_timeline_name = drm_sched_fence_get_timeline_name,
 190         .release = drm_sched_fence_release_finished,
 191         .set_deadline = drm_sched_fence_set_deadline_finished,
 192 };
 193
 194 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
 195 {
 196         if (f->ops == &drm_sched_fence_ops_scheduled)
 197                 return container_of(f, struct drm_sched_fence, scheduled);
 198
 199         if (f->ops == &drm_sched_fence_ops_finished)
 200                 return container_of(f, struct drm_sched_fence, finished);
 201
 202         return NULL;
 203 }
 204 EXPORT_SYMBOL(to_drm_sched_fence);
 205
 206 struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
 207                                               void *owner)
 208 {
 209         struct drm_sched_fence *fence = NULL;
 210
 211         fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
 212         if (fence == NULL)
 213                 return NULL;
 214
 215         fence->owner = owner;
 216         spin_lock_init(&fence->lock);
 217
 218         return fence;
 219 }
 220
 221 void drm_sched_fence_init(struct drm_sched_fence *fence,
 222                           struct drm_sched_entity *entity)
 223 {
 224         unsigned seq;
 225
 226         fence->sched = entity->rq->sched;
 227         seq = atomic_inc_return(&entity->fence_seq);
 228         dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
 229                        &fence->lock, entity->fence_context, seq);
 230         dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
 231                        &fence->lock, entity->fence_context + 1, seq);
 232 }
 233
 234 module_init(drm_sched_fence_slab_init);
 235 module_exit(drm_sched_fence_slab_fini);
 236
 237 MODULE_DESCRIPTION("DRM GPU scheduler");
 238 MODULE_LICENSE("GPL and additional rights");