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