drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c - linux - Git at Google

 /*
  * Copyright 2014 Advanced Micro Devices, Inc.
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  */
 /*
  * Authors:
  *    Christian König <christian.koenig@amd.com>
  */

 #include "amdgpu.h"
 #include "amdgpu_trace.h"
 #include "amdgpu_amdkfd.h"

 struct amdgpu_sync_entry {
 	struct hlist_node	node;
 	struct dma_fence	*fence;
 	bool	explicit;
 };

 static struct kmem_cache *amdgpu_sync_slab;

 /**
  * amdgpu_sync_create - zero init sync object
  *
  * @sync: sync object to initialize
  *
  * Just clear the sync object for now.
  */
 void amdgpu_sync_create(struct amdgpu_sync *sync)
 {
 	hash_init(sync->fences);
 	sync->last_vm_update = NULL;
 }

 /**
  * amdgpu_sync_same_dev - test if fence belong to us
  *
  * @adev: amdgpu device to use for the test
  * @f: fence to test
  *
  * Test if the fence was issued by us.
  */
 static bool amdgpu_sync_same_dev(struct amdgpu_device *adev,
 				 struct dma_fence *f)
 {
 	struct drm_sched_fence *s_fence = to_drm_sched_fence(f);

 	if (s_fence) {
 		struct amdgpu_ring *ring;

 		ring = container_of(s_fence->sched, struct amdgpu_ring, sched);
 		return ring->adev == adev;
 	}

 	return false;
 }

 /**
  * amdgpu_sync_get_owner - extract the owner of a fence
  *
  * @fence: fence get the owner from
  *
  * Extract who originally created the fence.
  */
 static void *amdgpu_sync_get_owner(struct dma_fence *f)
 {
 	struct drm_sched_fence *s_fence;
 	struct amdgpu_amdkfd_fence *kfd_fence;

 	if (!f)
 		return AMDGPU_FENCE_OWNER_UNDEFINED;

 	s_fence = to_drm_sched_fence(f);
 	if (s_fence)
 		return s_fence->owner;

 	kfd_fence = to_amdgpu_amdkfd_fence(f);
 	if (kfd_fence)
 		return AMDGPU_FENCE_OWNER_KFD;

 	return AMDGPU_FENCE_OWNER_UNDEFINED;
 }

 /**
  * amdgpu_sync_keep_later - Keep the later fence
  *
  * @keep: existing fence to test
  * @fence: new fence
  *
  * Either keep the existing fence or the new one, depending which one is later.
  */
 static void amdgpu_sync_keep_later(struct dma_fence **keep,
 				   struct dma_fence *fence)
 {
 	if (*keep && dma_fence_is_later(*keep, fence))
 		return;

 	dma_fence_put(*keep);
 	*keep = dma_fence_get(fence);
 }

 /**
  * amdgpu_sync_add_later - add the fence to the hash
  *
  * @sync: sync object to add the fence to
  * @f: fence to add
  *
  * Tries to add the fence to an existing hash entry. Returns true when an entry
  * was found, false otherwise.
  */
 static bool amdgpu_sync_add_later(struct amdgpu_sync *sync, struct dma_fence *f,
 				  bool explicit)
 {
 	struct amdgpu_sync_entry *e;

 	hash_for_each_possible(sync->fences, e, node, f->context) {
 		if (unlikely(e->fence->context != f->context))
 			continue;

 		amdgpu_sync_keep_later(&e->fence, f);

 		/* Preserve eplicit flag to not loose pipe line sync */
 		e->explicit |= explicit;

 		return true;
 	}
 	return false;
 }

 /**
  * amdgpu_sync_fence - remember to sync to this fence
  *
  * @sync: sync object to add fence to
  * @f: fence to sync to
  * @explicit: if this is an explicit dependency
  *
  * Add the fence to the sync object.
  */
 int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f,
 		      bool explicit)
 {
 	struct amdgpu_sync_entry *e;

 	if (!f)
 		return 0;

 	if (amdgpu_sync_add_later(sync, f, explicit))
 		return 0;

 	e = kmem_cache_alloc(amdgpu_sync_slab, GFP_KERNEL);
 	if (!e)
 		return -ENOMEM;

 	e->explicit = explicit;

 	hash_add(sync->fences, &e->node, f->context);
 	e->fence = dma_fence_get(f);
 	return 0;
 }

 /**
  * amdgpu_sync_vm_fence - remember to sync to this VM fence
  *
  * @adev: amdgpu device
  * @sync: sync object to add fence to
  * @fence: the VM fence to add
  *
  * Add the fence to the sync object and remember it as VM update.
  */
 int amdgpu_sync_vm_fence(struct amdgpu_sync *sync, struct dma_fence *fence)
 {
 	if (!fence)
 		return 0;

 	amdgpu_sync_keep_later(&sync->last_vm_update, fence);
 	return amdgpu_sync_fence(sync, fence, false);
 }

 /**
  * amdgpu_sync_resv - sync to a reservation object
  *
  * @sync: sync object to add fences from reservation object to
  * @resv: reservation object with embedded fence
  * @explicit_sync: true if we should only sync to the exclusive fence
  *
  * Sync to the fence
  */
 int amdgpu_sync_resv(struct amdgpu_device *adev,
 		     struct amdgpu_sync *sync,
 		     struct dma_resv *resv,
 		     void *owner, bool explicit_sync)
 {
 	struct dma_resv_list *flist;
 	struct dma_fence *f;
 	void *fence_owner;
 	unsigned i;
 	int r = 0;

 	if (resv == NULL)
 		return -EINVAL;

 	/* always sync to the exclusive fence */
 	f = dma_resv_get_excl(resv);
 	r = amdgpu_sync_fence(sync, f, false);

 	flist = dma_resv_get_list(resv);
 	if (!flist || r)
 		return r;

 	for (i = 0; i < flist->shared_count; ++i) {
 		f = rcu_dereference_protected(flist->shared[i],
 					      dma_resv_held(resv));
 		/* We only want to trigger KFD eviction fences on
 		 * evict or move jobs. Skip KFD fences otherwise.
 		 */
 		fence_owner = amdgpu_sync_get_owner(f);
 		if (fence_owner == AMDGPU_FENCE_OWNER_KFD &&
 		    owner != AMDGPU_FENCE_OWNER_UNDEFINED)
 			continue;

 		if (amdgpu_sync_same_dev(adev, f)) {
 			/* VM updates only sync with moves but not with user
 			 * command submissions or KFD evictions fences
 			 */
 			if (owner == AMDGPU_FENCE_OWNER_VM &&
 			    fence_owner != AMDGPU_FENCE_OWNER_UNDEFINED)
 				continue;

 			/* Ignore fence from the same owner and explicit one as
 			 * long as it isn't undefined.
 			 */
 			if (owner != AMDGPU_FENCE_OWNER_UNDEFINED &&
 			    (fence_owner == owner || explicit_sync))
 				continue;
 		}

 		r = amdgpu_sync_fence(sync, f, false);
 		if (r)
 			break;
 	}
 	return r;
 }

 /**
  * amdgpu_sync_peek_fence - get the next fence not signaled yet
  *
  * @sync: the sync object
  * @ring: optional ring to use for test
  *
  * Returns the next fence not signaled yet without removing it from the sync
  * object.
  */
 struct dma_fence *amdgpu_sync_peek_fence(struct amdgpu_sync *sync,
 					 struct amdgpu_ring *ring)
 {
 	struct amdgpu_sync_entry *e;
 	struct hlist_node *tmp;
 	int i;

 	hash_for_each_safe(sync->fences, i, tmp, e, node) {
 		struct dma_fence *f = e->fence;
 		struct drm_sched_fence *s_fence = to_drm_sched_fence(f);

 		if (dma_fence_is_signaled(f)) {
 			hash_del(&e->node);
 			dma_fence_put(f);
 			kmem_cache_free(amdgpu_sync_slab, e);
 			continue;
 		}
 		if (ring && s_fence) {
 			/* For fences from the same ring it is sufficient
 			 * when they are scheduled.
 			 */
 			if (s_fence->sched == &ring->sched) {
 				if (dma_fence_is_signaled(&s_fence->scheduled))
 					continue;

 				return &s_fence->scheduled;
 			}
 		}

 		return f;
 	}

 	return NULL;
 }

 /**
  * amdgpu_sync_get_fence - get the next fence from the sync object
  *
  * @sync: sync object to use
  * @explicit: true if the next fence is explicit
  *
  * Get and removes the next fence from the sync object not signaled yet.
  */
 struct dma_fence *amdgpu_sync_get_fence(struct amdgpu_sync *sync, bool *explicit)
 {
 	struct amdgpu_sync_entry *e;
 	struct hlist_node *tmp;
 	struct dma_fence *f;
 	int i;
 	hash_for_each_safe(sync->fences, i, tmp, e, node) {

 		f = e->fence;
 		if (explicit)
 			*explicit = e->explicit;

 		hash_del(&e->node);
 		kmem_cache_free(amdgpu_sync_slab, e);

 		if (!dma_fence_is_signaled(f))
 			return f;

 		dma_fence_put(f);
 	}
 	return NULL;
 }

 /**
  * amdgpu_sync_clone - clone a sync object
  *
  * @source: sync object to clone
  * @clone: pointer to destination sync object
  *
  * Adds references to all unsignaled fences in @source to @clone. Also
  * removes signaled fences from @source while at it.
  */
 int amdgpu_sync_clone(struct amdgpu_sync *source, struct amdgpu_sync *clone)
 {
 	struct amdgpu_sync_entry *e;
 	struct hlist_node *tmp;
 	struct dma_fence *f;
 	int i, r;

 	hash_for_each_safe(source->fences, i, tmp, e, node) {
 		f = e->fence;
 		if (!dma_fence_is_signaled(f)) {
 			r = amdgpu_sync_fence(clone, f, e->explicit);
 			if (r)
 				return r;
 		} else {
 			hash_del(&e->node);
 			dma_fence_put(f);
 			kmem_cache_free(amdgpu_sync_slab, e);
 		}
 	}

 	dma_fence_put(clone->last_vm_update);
 	clone->last_vm_update = dma_fence_get(source->last_vm_update);

 	return 0;
 }

 int amdgpu_sync_wait(struct amdgpu_sync *sync, bool intr)
 {
 	struct amdgpu_sync_entry *e;
 	struct hlist_node *tmp;
 	int i, r;

 	hash_for_each_safe(sync->fences, i, tmp, e, node) {
 		r = dma_fence_wait(e->fence, intr);
 		if (r)
 			return r;

 		hash_del(&e->node);
 		dma_fence_put(e->fence);
 		kmem_cache_free(amdgpu_sync_slab, e);
 	}

 	return 0;
 }

 /**
  * amdgpu_sync_free - free the sync object
  *
  * @sync: sync object to use
  *
  * Free the sync object.
  */
 void amdgpu_sync_free(struct amdgpu_sync *sync)
 {
 	struct amdgpu_sync_entry *e;
 	struct hlist_node *tmp;
 	unsigned i;

 	hash_for_each_safe(sync->fences, i, tmp, e, node) {
 		hash_del(&e->node);
 		dma_fence_put(e->fence);
 		kmem_cache_free(amdgpu_sync_slab, e);
 	}

 	dma_fence_put(sync->last_vm_update);
 }

 /**
  * amdgpu_sync_init - init sync object subsystem
  *
  * Allocate the slab allocator.
  */
 int amdgpu_sync_init(void)
 {
 	amdgpu_sync_slab = kmem_cache_create(
 		"amdgpu_sync", sizeof(struct amdgpu_sync_entry), 0,
 		SLAB_HWCACHE_ALIGN, NULL);
 	if (!amdgpu_sync_slab)
 		return -ENOMEM;

 	return 0;
 }

 /**
  * amdgpu_sync_fini - fini sync object subsystem
  *
  * Free the slab allocator.
  */
 void amdgpu_sync_fini(void)
 {
 	kmem_cache_destroy(amdgpu_sync_slab);
 }
	/*
	* Copyright 2014 Advanced Micro Devices, Inc.
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sub license, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
	* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
	* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
	* USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	* The above copyright notice and this permission notice (including the
	* next paragraph) shall be included in all copies or substantial portions
	* of the Software.
	*
	*/
	/*
	* Authors:
	* Christian König <christian.koenig@amd.com>
	*/

	#include "amdgpu.h"
	#include "amdgpu_trace.h"
	#include "amdgpu_amdkfd.h"

	struct amdgpu_sync_entry {
	struct hlist_node node;
	struct dma_fence *fence;
	bool explicit;
	};

	static struct kmem_cache *amdgpu_sync_slab;

	/**
	* amdgpu_sync_create - zero init sync object
	*
	* @sync: sync object to initialize
	*
	* Just clear the sync object for now.
	*/
	void amdgpu_sync_create(struct amdgpu_sync *sync)
	{
	hash_init(sync->fences);
	sync->last_vm_update = NULL;
	}

	/**
	* amdgpu_sync_same_dev - test if fence belong to us
	*
	* @adev: amdgpu device to use for the test
	* @f: fence to test
	*
	* Test if the fence was issued by us.
	*/
	static bool amdgpu_sync_same_dev(struct amdgpu_device *adev,
	struct dma_fence *f)
	{
	struct drm_sched_fence *s_fence = to_drm_sched_fence(f);

	if (s_fence) {
	struct amdgpu_ring *ring;

	ring = container_of(s_fence->sched, struct amdgpu_ring, sched);
	return ring->adev == adev;
	}

	return false;
	}

	/**
	* amdgpu_sync_get_owner - extract the owner of a fence
	*
	* @fence: fence get the owner from
	*
	* Extract who originally created the fence.
	*/
	static void amdgpu_sync_get_owner(struct dma_fence f)
	{
	struct drm_sched_fence *s_fence;
	struct amdgpu_amdkfd_fence *kfd_fence;

	if (!f)
	return AMDGPU_FENCE_OWNER_UNDEFINED;

	s_fence = to_drm_sched_fence(f);
	if (s_fence)
	return s_fence->owner;

	kfd_fence = to_amdgpu_amdkfd_fence(f);
	if (kfd_fence)
	return AMDGPU_FENCE_OWNER_KFD;

	return AMDGPU_FENCE_OWNER_UNDEFINED;
	}

	/**
	* amdgpu_sync_keep_later - Keep the later fence
	*
	* @keep: existing fence to test
	* @fence: new fence
	*
	* Either keep the existing fence or the new one, depending which one is later.
	*/
	static void amdgpu_sync_keep_later(struct dma_fence **keep,
	struct dma_fence *fence)
	{
	if (keep && dma_fence_is_later(keep, fence))
	return;

	dma_fence_put(*keep);
	*keep = dma_fence_get(fence);
	}

	/**
	* amdgpu_sync_add_later - add the fence to the hash
	*
	* @sync: sync object to add the fence to
	* @f: fence to add
	*
	* Tries to add the fence to an existing hash entry. Returns true when an entry
	* was found, false otherwise.
	*/
	static bool amdgpu_sync_add_later(struct amdgpu_sync sync, struct dma_fence f,
	bool explicit)
	{
	struct amdgpu_sync_entry *e;

	hash_for_each_possible(sync->fences, e, node, f->context) {
	if (unlikely(e->fence->context != f->context))
	continue;

	amdgpu_sync_keep_later(&e->fence, f);

	/* Preserve eplicit flag to not loose pipe line sync */
	e->explicit \|= explicit;

	return true;
	}
	return false;
	}

	/**
	* amdgpu_sync_fence - remember to sync to this fence
	*
	* @sync: sync object to add fence to
	* @f: fence to sync to
	* @explicit: if this is an explicit dependency
	*
	* Add the fence to the sync object.
	*/
	int amdgpu_sync_fence(struct amdgpu_sync sync, struct dma_fence f,
	bool explicit)
	{
	struct amdgpu_sync_entry *e;

	if (!f)
	return 0;

	if (amdgpu_sync_add_later(sync, f, explicit))
	return 0;

	e = kmem_cache_alloc(amdgpu_sync_slab, GFP_KERNEL);
	if (!e)
	return -ENOMEM;

	e->explicit = explicit;

	hash_add(sync->fences, &e->node, f->context);
	e->fence = dma_fence_get(f);
	return 0;
	}

	/**
	* amdgpu_sync_vm_fence - remember to sync to this VM fence
	*
	* @adev: amdgpu device
	* @sync: sync object to add fence to
	* @fence: the VM fence to add
	*
	* Add the fence to the sync object and remember it as VM update.
	*/
	int amdgpu_sync_vm_fence(struct amdgpu_sync sync, struct dma_fence fence)
	{
	if (!fence)
	return 0;

	amdgpu_sync_keep_later(&sync->last_vm_update, fence);
	return amdgpu_sync_fence(sync, fence, false);
	}

	/**
	* amdgpu_sync_resv - sync to a reservation object
	*
	* @sync: sync object to add fences from reservation object to
	* @resv: reservation object with embedded fence
	* @explicit_sync: true if we should only sync to the exclusive fence
	*
	* Sync to the fence
	*/
	int amdgpu_sync_resv(struct amdgpu_device *adev,
	struct amdgpu_sync *sync,
	struct dma_resv *resv,
	void *owner, bool explicit_sync)
	{
	struct dma_resv_list *flist;
	struct dma_fence *f;
	void *fence_owner;
	unsigned i;
	int r = 0;

	if (resv == NULL)
	return -EINVAL;

	/* always sync to the exclusive fence */
	f = dma_resv_get_excl(resv);
	r = amdgpu_sync_fence(sync, f, false);

	flist = dma_resv_get_list(resv);
	if (!flist \|\| r)
	return r;

	for (i = 0; i < flist->shared_count; ++i) {
	f = rcu_dereference_protected(flist->shared[i],
	dma_resv_held(resv));
	/* We only want to trigger KFD eviction fences on
	* evict or move jobs. Skip KFD fences otherwise.
	*/
	fence_owner = amdgpu_sync_get_owner(f);
	if (fence_owner == AMDGPU_FENCE_OWNER_KFD &&
	owner != AMDGPU_FENCE_OWNER_UNDEFINED)
	continue;

	if (amdgpu_sync_same_dev(adev, f)) {
	/* VM updates only sync with moves but not with user
	* command submissions or KFD evictions fences
	*/
	if (owner == AMDGPU_FENCE_OWNER_VM &&
	fence_owner != AMDGPU_FENCE_OWNER_UNDEFINED)
	continue;

	/* Ignore fence from the same owner and explicit one as
	* long as it isn't undefined.
	*/
	if (owner != AMDGPU_FENCE_OWNER_UNDEFINED &&
	(fence_owner == owner \|\| explicit_sync))
	continue;
	}

	r = amdgpu_sync_fence(sync, f, false);
	if (r)
	break;
	}
	return r;
	}

	/**
	* amdgpu_sync_peek_fence - get the next fence not signaled yet
	*
	* @sync: the sync object
	* @ring: optional ring to use for test
	*
	* Returns the next fence not signaled yet without removing it from the sync
	* object.
	*/
	struct dma_fence amdgpu_sync_peek_fence(struct amdgpu_sync sync,
	struct amdgpu_ring *ring)
	{
	struct amdgpu_sync_entry *e;
	struct hlist_node *tmp;
	int i;

	hash_for_each_safe(sync->fences, i, tmp, e, node) {
	struct dma_fence *f = e->fence;
	struct drm_sched_fence *s_fence = to_drm_sched_fence(f);

	if (dma_fence_is_signaled(f)) {
	hash_del(&e->node);
	dma_fence_put(f);
	kmem_cache_free(amdgpu_sync_slab, e);
	continue;
	}
	if (ring && s_fence) {
	/* For fences from the same ring it is sufficient
	* when they are scheduled.
	*/
	if (s_fence->sched == &ring->sched) {
	if (dma_fence_is_signaled(&s_fence->scheduled))
	continue;

	return &s_fence->scheduled;
	}
	}

	return f;
	}

	return NULL;
	}

	/**
	* amdgpu_sync_get_fence - get the next fence from the sync object
	*
	* @sync: sync object to use
	* @explicit: true if the next fence is explicit
	*
	* Get and removes the next fence from the sync object not signaled yet.
	*/
	struct dma_fence amdgpu_sync_get_fence(struct amdgpu_sync sync, bool *explicit)
	{
	struct amdgpu_sync_entry *e;
	struct hlist_node *tmp;
	struct dma_fence *f;
	int i;
	hash_for_each_safe(sync->fences, i, tmp, e, node) {

	f = e->fence;
	if (explicit)
	*explicit = e->explicit;

	hash_del(&e->node);
	kmem_cache_free(amdgpu_sync_slab, e);

	if (!dma_fence_is_signaled(f))
	return f;

	dma_fence_put(f);
	}
	return NULL;
	}

	/**
	* amdgpu_sync_clone - clone a sync object
	*
	* @source: sync object to clone
	* @clone: pointer to destination sync object
	*
	* Adds references to all unsignaled fences in @source to @clone. Also
	* removes signaled fences from @source while at it.
	*/
	int amdgpu_sync_clone(struct amdgpu_sync source, struct amdgpu_sync clone)
	{
	struct amdgpu_sync_entry *e;
	struct hlist_node *tmp;
	struct dma_fence *f;
	int i, r;

	hash_for_each_safe(source->fences, i, tmp, e, node) {
	f = e->fence;
	if (!dma_fence_is_signaled(f)) {
	r = amdgpu_sync_fence(clone, f, e->explicit);
	if (r)
	return r;
	} else {
	hash_del(&e->node);
	dma_fence_put(f);
	kmem_cache_free(amdgpu_sync_slab, e);
	}
	}

	dma_fence_put(clone->last_vm_update);
	clone->last_vm_update = dma_fence_get(source->last_vm_update);

	return 0;
	}

	int amdgpu_sync_wait(struct amdgpu_sync *sync, bool intr)
	{
	struct amdgpu_sync_entry *e;
	struct hlist_node *tmp;
	int i, r;

	hash_for_each_safe(sync->fences, i, tmp, e, node) {
	r = dma_fence_wait(e->fence, intr);
	if (r)
	return r;

	hash_del(&e->node);
	dma_fence_put(e->fence);
	kmem_cache_free(amdgpu_sync_slab, e);
	}

	return 0;
	}

	/**
	* amdgpu_sync_free - free the sync object
	*
	* @sync: sync object to use
	*
	* Free the sync object.
	*/
	void amdgpu_sync_free(struct amdgpu_sync *sync)
	{
	struct amdgpu_sync_entry *e;
	struct hlist_node *tmp;
	unsigned i;

	hash_for_each_safe(sync->fences, i, tmp, e, node) {
	hash_del(&e->node);
	dma_fence_put(e->fence);
	kmem_cache_free(amdgpu_sync_slab, e);
	}

	dma_fence_put(sync->last_vm_update);
	}

	/**
	* amdgpu_sync_init - init sync object subsystem
	*
	* Allocate the slab allocator.
	*/
	int amdgpu_sync_init(void)
	{
	amdgpu_sync_slab = kmem_cache_create(
	"amdgpu_sync", sizeof(struct amdgpu_sync_entry), 0,
	SLAB_HWCACHE_ALIGN, NULL);
	if (!amdgpu_sync_slab)
	return -ENOMEM;

	return 0;
	}

	/**
	* amdgpu_sync_fini - fini sync object subsystem
	*
	* Free the slab allocator.
	*/
	void amdgpu_sync_fini(void)
	{
	kmem_cache_destroy(amdgpu_sync_slab);
	}