xref: /linux/drivers/gpu/drm/scheduler/sched_fence.c (revision 79790b6818e96c58fe2bffee1b418c16e64e7b80)
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 
drm_sched_fence_slab_init(void)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 
drm_sched_fence_slab_fini(void)43 static void __exit drm_sched_fence_slab_fini(void)
44 {
45 	rcu_barrier();
46 	kmem_cache_destroy(sched_fence_slab);
47 }
48 
drm_sched_fence_set_parent(struct drm_sched_fence * s_fence,struct dma_fence * fence)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 
drm_sched_fence_scheduled(struct drm_sched_fence * fence,struct dma_fence * parent)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 
drm_sched_fence_finished(struct drm_sched_fence * fence,int result)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 
drm_sched_fence_get_driver_name(struct dma_fence * fence)85 static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
86 {
87 	return "drm_sched";
88 }
89 
drm_sched_fence_get_timeline_name(struct dma_fence * f)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 
drm_sched_fence_free_rcu(struct rcu_head * rcu)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  */
drm_sched_fence_free(struct drm_sched_fence * fence)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  */
drm_sched_fence_release_scheduled(struct dma_fence * f)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  */
drm_sched_fence_release_finished(struct dma_fence * f)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 
drm_sched_fence_set_deadline_finished(struct dma_fence * f,ktime_t deadline)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 
to_drm_sched_fence(struct dma_fence * f)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 
drm_sched_fence_alloc(struct drm_sched_entity * entity,void * owner)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 
drm_sched_fence_init(struct drm_sched_fence * fence,struct drm_sched_entity * entity)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");
239