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dma-buf & drm/amdgpu: remove dma_resv workaround

Browse source 
Rework the internals of the dma_resv object to allow adding more than one
write fence and remember for each fence what purpose it had.

This allows removing the workaround from amdgpu which used a container for
this instead.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-4-christian.koenig@amd.com
This commit is contained in:
Christian König 2021-11-23 09:33:07 +01:00
parent 73511edf8b
commit 047a1b877e
4 changed files with 157 additions and 297 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

353
drivers/dma-buf/dma-resv.c
View file

@ -44,12 +44,12 @@
/**
* DOC: Reservation Object Overview
*
* The reservation object provides a mechanism to manage shared and
* exclusive fences associated with a buffer. A reservation object
* can have attached one exclusive fence (normally associated with
* write operations) or N shared fences (read operations). The RCU
* mechanism is used to protect read access to fences from locked
* write-side updates.
* The reservation object provides a mechanism to manage a container of
* dma_fence object associated with a resource. A reservation object
* can have any number of fences attaches to it. Each fence carries an usage
* parameter determining how the operation represented by the fence is using the
* resource. The RCU mechanism is used to protect read access to fences from
* locked write-side updates.
*
* See struct dma_resv for more details.
*/
@ -57,39 +57,59 @@
DEFINE_WD_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
/* Mask for the lower fence pointer bits */
#define DMA_RESV_LIST_MASK 0x3
struct dma_resv_list {
struct rcu_head rcu;
u32 shared_count, shared_max;
struct dma_fence __rcu *shared[];
u32 num_fences, max_fences;
struct dma_fence __rcu *table[];
};
/**
* dma_resv_list_alloc - allocate fence list
* @shared_max: number of fences we need space for
*
/* Extract the fence and usage flags from an RCU protected entry in the list. */
static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
struct dma_resv *resv, struct dma_fence **fence,
enum dma_resv_usage *usage)
{
long tmp;
tmp = (long)rcu_dereference_check(list->table[index],
resv ? dma_resv_held(resv) : true);
*fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
if (usage)
*usage = tmp & DMA_RESV_LIST_MASK;
}
/* Set the fence and usage flags at the specific index in the list. */
static void dma_resv_list_set(struct dma_resv_list *list,
unsigned int index,
struct dma_fence *fence,
enum dma_resv_usage usage)
{
long tmp = ((long)fence) | usage;
RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
}
/*
* Allocate a new dma_resv_list and make sure to correctly initialize
* shared_max.
* max_fences.
*/
static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
{
struct dma_resv_list *list;
list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL);
if (!list)
return NULL;
list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
sizeof(*list->shared);
list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) /
sizeof(*list->table);
return list;
}
/**
* dma_resv_list_free - free fence list
* @list: list to free
*
* Free a dma_resv_list and make sure to drop all references.
*/
/* Free a dma_resv_list and make sure to drop all references. */
static void dma_resv_list_free(struct dma_resv_list *list)
{
unsigned int i;
@ -97,9 +117,12 @@ static void dma_resv_list_free(struct dma_resv_list *list)
if (!list)
return;
for (i = 0; i < list->shared_count; ++i)
dma_fence_put(rcu_dereference_protected(list->shared[i], true));
for (i = 0; i < list->num_fences; ++i) {
struct dma_fence *fence;
dma_resv_list_entry(list, i, NULL, &fence, NULL);
dma_fence_put(fence);
}
kfree_rcu(list, rcu);
}
@ -112,8 +135,7 @@ void dma_resv_init(struct dma_resv *obj)
ww_mutex_init(&obj->lock, &reservation_ww_class);
seqcount_ww_mutex_init(&obj->seq, &obj->lock);
RCU_INIT_POINTER(obj->fence, NULL);
RCU_INIT_POINTER(obj->fence_excl, NULL);
RCU_INIT_POINTER(obj->fences, NULL);
}
EXPORT_SYMBOL(dma_resv_init);
@ -123,46 +145,32 @@ EXPORT_SYMBOL(dma_resv_init);
*/
void dma_resv_fini(struct dma_resv *obj)
{
struct dma_resv_list *fobj;
struct dma_fence *excl;
/*
* This object should be dead and all references must have
* been released to it, so no need to be protected with rcu.
*/
excl = rcu_dereference_protected(obj->fence_excl, 1);
if (excl)
dma_fence_put(excl);
fobj = rcu_dereference_protected(obj->fence, 1);
dma_resv_list_free(fobj);
dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
ww_mutex_destroy(&obj->lock);
}
EXPORT_SYMBOL(dma_resv_fini);
static inline struct dma_fence *
dma_resv_excl_fence(struct dma_resv *obj)
/* Dereference the fences while ensuring RCU rules */
static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
{
return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj));
}
static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj)
{
return rcu_dereference_check(obj->fence, dma_resv_held(obj));
return rcu_dereference_check(obj->fences, dma_resv_held(obj));
}
/**
* dma_resv_reserve_fences - Reserve space to add shared fences to
* a dma_resv.
* dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
* @obj: reservation object
* @num_fences: number of fences we want to add
*
* Should be called before dma_resv_add_shared_fence(). Must
* be called with @obj locked through dma_resv_lock().
* Should be called before dma_resv_add_fence(). Must be called with @obj
* locked through dma_resv_lock().
*
* Note that the preallocated slots need to be re-reserved if @obj is unlocked
* at any time before calling dma_resv_add_shared_fence(). This is validated
* when CONFIG_DEBUG_MUTEXES is enabled.
* at any time before calling dma_resv_add_fence(). This is validated when
* CONFIG_DEBUG_MUTEXES is enabled.
*
* RETURNS
* Zero for success, or -errno
@ -174,11 +182,11 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
dma_resv_assert_held(obj);
old = dma_resv_shared_list(obj);
if (old && old->shared_max) {
if ((old->shared_count + num_fences) <= old->shared_max)
old = dma_resv_fences_list(obj);
if (old && old->max_fences) {
if ((old->num_fences + num_fences) <= old->max_fences)
return 0;
max = max(old->shared_count + num_fences, old->shared_max * 2);
max = max(old->num_fences + num_fences, old->max_fences * 2);
} else {
max = max(4ul, roundup_pow_of_two(num_fences));
}
@ -193,27 +201,27 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
* references from the old struct are carried over to
* the new.
*/
for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
enum dma_resv_usage usage;
struct dma_fence *fence;
fence = rcu_dereference_protected(old->shared[i],
dma_resv_held(obj));
dma_resv_list_entry(old, i, obj, &fence, &usage);
if (dma_fence_is_signaled(fence))
RCU_INIT_POINTER(new->shared[--k], fence);
RCU_INIT_POINTER(new->table[--k], fence);
else
RCU_INIT_POINTER(new->shared[j++], fence);
dma_resv_list_set(new, j++, fence, usage);
}
new->shared_count = j;
new->num_fences = j;
/*
* We are not changing the effective set of fences here so can
* merely update the pointer to the new array; both existing
* readers and new readers will see exactly the same set of
* active (unsignaled) shared fences. Individual fences and the
* active (unsignaled) fences. Individual fences and the
* old array are protected by RCU and so will not vanish under
* the gaze of the rcu_read_lock() readers.
*/
rcu_assign_pointer(obj->fence, new);
rcu_assign_pointer(obj->fences, new);
if (!old)
return 0;
@ -222,7 +230,7 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
for (i = k; i < max; ++i) {
struct dma_fence *fence;
fence = rcu_dereference_protected(new->shared[i],
fence = rcu_dereference_protected(new->table[i],
dma_resv_held(obj));
dma_fence_put(fence);
}
@ -234,38 +242,39 @@ EXPORT_SYMBOL(dma_resv_reserve_fences);
#ifdef CONFIG_DEBUG_MUTEXES
/**
* dma_resv_reset_max_fences - reset shared fences for debugging
* dma_resv_reset_max_fences - reset fences for debugging
* @obj: the dma_resv object to reset
*
* Reset the number of pre-reserved shared slots to test that drivers do
* Reset the number of pre-reserved fence slots to test that drivers do
* correct slot allocation using dma_resv_reserve_fences(). See also
* &dma_resv_list.shared_max.
* &dma_resv_list.max_fences.
*/
void dma_resv_reset_max_fences(struct dma_resv *obj)
{
struct dma_resv_list *fences = dma_resv_shared_list(obj);
struct dma_resv_list *fences = dma_resv_fences_list(obj);
dma_resv_assert_held(obj);
/* Test shared fence slot reservation */
/* Test fence slot reservation */
if (fences)
fences->shared_max = fences->shared_count;
fences->max_fences = fences->num_fences;
}
EXPORT_SYMBOL(dma_resv_reset_max_fences);
#endif
/**
* dma_resv_add_shared_fence - Add a fence to a shared slot
* dma_resv_add_fence - Add a fence to the dma_resv obj
* @obj: the reservation object
* @fence: the shared fence to add
* @fence: the fence to add
* @usage: how the fence is used, see enum dma_resv_usage
*
* Add a fence to a shared slot, @obj must be locked with dma_resv_lock(), and
* Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
* dma_resv_reserve_fences() has been called.
*
* See also &dma_resv.fence for a discussion of the semantics.
*/
static void dma_resv_add_shared_fence(struct dma_resv *obj,
struct dma_fence *fence)
void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
enum dma_resv_usage usage)
{
struct dma_resv_list *fobj;
struct dma_fence *old;
@ -280,32 +289,33 @@ static void dma_resv_add_shared_fence(struct dma_resv *obj,
*/
WARN_ON(dma_fence_is_container(fence));
fobj = dma_resv_shared_list(obj);
count = fobj->shared_count;
fobj = dma_resv_fences_list(obj);
count = fobj->num_fences;
write_seqcount_begin(&obj->seq);
for (i = 0; i < count; ++i) {
enum dma_resv_usage old_usage;
old = rcu_dereference_protected(fobj->shared[i],
dma_resv_held(obj));
if (old->context == fence->context ||
dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
if ((old->context == fence->context && old_usage >= usage) ||
dma_fence_is_signaled(old))
goto replace;
}
BUG_ON(fobj->shared_count >= fobj->shared_max);
BUG_ON(fobj->num_fences >= fobj->max_fences);
old = NULL;
count++;
replace:
RCU_INIT_POINTER(fobj->shared[i], fence);
/* pointer update must be visible before we extend the shared_count */
smp_store_mb(fobj->shared_count, count);
dma_resv_list_set(fobj, i, fence, usage);
/* pointer update must be visible before we extend the num_fences */
smp_store_mb(fobj->num_fences, count);
write_seqcount_end(&obj->seq);
dma_fence_put(old);
}
EXPORT_SYMBOL(dma_resv_add_fence);
/**
* dma_resv_replace_fences - replace fences in the dma_resv obj
@ -326,128 +336,63 @@ void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
enum dma_resv_usage usage)
{
struct dma_resv_list *list;
struct dma_fence *old;
unsigned int i;
/* Only readers supported for now */
WARN_ON(usage != DMA_RESV_USAGE_READ);
dma_resv_assert_held(obj);
list = dma_resv_fences_list(obj);
write_seqcount_begin(&obj->seq);
for (i = 0; list && i < list->num_fences; ++i) {
struct dma_fence *old;
old = dma_resv_excl_fence(obj);
if (old->context == context) {
RCU_INIT_POINTER(obj->fence_excl, dma_fence_get(replacement));
dma_fence_put(old);
}
list = dma_resv_shared_list(obj);
for (i = 0; list && i < list->shared_count; ++i) {
old = rcu_dereference_protected(list->shared[i],
dma_resv_held(obj));
dma_resv_list_entry(list, i, obj, &old, NULL);
if (old->context != context)
continue;
rcu_assign_pointer(list->shared[i], dma_fence_get(replacement));
dma_resv_list_set(list, i, replacement, usage);
dma_fence_put(old);
}
write_seqcount_end(&obj->seq);
}
EXPORT_SYMBOL(dma_resv_replace_fences);
/**
* dma_resv_add_excl_fence - Add an exclusive fence.
* @obj: the reservation object
* @fence: the exclusive fence to add
*
* Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
* See also &dma_resv.fence_excl for a discussion of the semantics.
*/
static void dma_resv_add_excl_fence(struct dma_resv *obj,
struct dma_fence *fence)
{
struct dma_fence *old_fence = dma_resv_excl_fence(obj);
dma_resv_assert_held(obj);
dma_fence_get(fence);
write_seqcount_begin(&obj->seq);
/* write_seqcount_begin provides the necessary memory barrier */
RCU_INIT_POINTER(obj->fence_excl, fence);
write_seqcount_end(&obj->seq);
dma_fence_put(old_fence);
}
/**
* dma_resv_add_fence - Add a fence to the dma_resv obj
* @obj: the reservation object
* @fence: the fence to add
* @usage: how the fence is used, see enum dma_resv_usage
*
* Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
* dma_resv_reserve_fences() has been called.
*
* See also &dma_resv.fence for a discussion of the semantics.
*/
void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
enum dma_resv_usage usage)
{
if (usage == DMA_RESV_USAGE_WRITE)
dma_resv_add_excl_fence(obj, fence);
else
dma_resv_add_shared_fence(obj, fence);
}
EXPORT_SYMBOL(dma_resv_add_fence);
/* Restart the iterator by initializing all the necessary fields, but not the
* relation to the dma_resv object. */
/* Restart the unlocked iteration by initializing the cursor object. */
static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
{
cursor->seq = read_seqcount_begin(&cursor->obj->seq);
cursor->index = -1;
cursor->shared_count = 0;
if (cursor->usage >= DMA_RESV_USAGE_READ) {
cursor->fences = dma_resv_shared_list(cursor->obj);
if (cursor->fences)
cursor->shared_count = cursor->fences->shared_count;
} else {
cursor->fences = NULL;
}
cursor->index = 0;
cursor->num_fences = 0;
cursor->fences = dma_resv_fences_list(cursor->obj);
if (cursor->fences)
cursor->num_fences = cursor->fences->num_fences;
cursor->is_restarted = true;
}
/* Walk to the next not signaled fence and grab a reference to it */
static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
{
struct dma_resv *obj = cursor->obj;
if (!cursor->fences)
return;
do {
/* Drop the reference from the previous round */
dma_fence_put(cursor->fence);
if (cursor->index == -1) {
cursor->fence = dma_resv_excl_fence(obj);
cursor->index++;
if (!cursor->fence)
continue;
} else if (!cursor->fences ||
cursor->index >= cursor->shared_count) {
if (cursor->index >= cursor->num_fences) {
cursor->fence = NULL;
break;
} else {
struct dma_resv_list *fences = cursor->fences;
unsigned int idx = cursor->index++;
cursor->fence = rcu_dereference(fences->shared[idx]);
}
dma_resv_list_entry(cursor->fences, cursor->index++,
cursor->obj, &cursor->fence,
&cursor->fence_usage);
cursor->fence = dma_fence_get_rcu(cursor->fence);
if (!cursor->fence || !dma_fence_is_signaled(cursor->fence))
if (!cursor->fence)
break;
if (!dma_fence_is_signaled(cursor->fence) &&
cursor->usage >= cursor->fence_usage)
break;
} while (true);
}
@ -522,15 +467,9 @@ struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
dma_resv_assert_held(cursor->obj);
cursor->index = 0;
if (cursor->usage >= DMA_RESV_USAGE_READ)
cursor->fences = dma_resv_shared_list(cursor->obj);
else
cursor->fences = NULL;
fence = dma_resv_excl_fence(cursor->obj);
if (!fence)
fence = dma_resv_iter_next(cursor);
cursor->fences = dma_resv_fences_list(cursor->obj);
fence = dma_resv_iter_next(cursor);
cursor->is_restarted = true;
return fence;
}
@ -545,17 +484,22 @@ EXPORT_SYMBOL_GPL(dma_resv_iter_first);
*/
struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
{
unsigned int idx;
struct dma_fence *fence;
dma_resv_assert_held(cursor->obj);
cursor->is_restarted = false;
if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
return NULL;
idx = cursor->index++;
return rcu_dereference_protected(cursor->fences->shared[idx],
dma_resv_held(cursor->obj));
do {
if (!cursor->fences ||
cursor->index >= cursor->fences->num_fences)
return NULL;
dma_resv_list_entry(cursor->fences, cursor->index++,
cursor->obj, &fence, &cursor->fence_usage);
} while (cursor->fence_usage > cursor->usage);
return fence;
}
EXPORT_SYMBOL_GPL(dma_resv_iter_next);
@ -570,57 +514,43 @@ int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
{
struct dma_resv_iter cursor;
struct dma_resv_list *list;
struct dma_fence *f, *excl;
struct dma_fence *f;
dma_resv_assert_held(dst);
list = NULL;
excl = NULL;
dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_READ);
dma_resv_for_each_fence_unlocked(&cursor, f) {
if (dma_resv_iter_is_restarted(&cursor)) {
dma_resv_list_free(list);
dma_fence_put(excl);
if (cursor.shared_count) {
list = dma_resv_list_alloc(cursor.shared_count);
if (!list) {
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
list->shared_count = 0;
} else {
list = NULL;
list = dma_resv_list_alloc(cursor.num_fences);
if (!list) {
dma_resv_iter_end(&cursor);
return -ENOMEM;
}
excl = NULL;
list->num_fences = 0;
}
dma_fence_get(f);
if (dma_resv_iter_usage(&cursor) == DMA_RESV_USAGE_WRITE)
excl = f;
else
RCU_INIT_POINTER(list->shared[list->shared_count++], f);
dma_resv_list_set(list, list->num_fences++, f,
dma_resv_iter_usage(&cursor));
}
dma_resv_iter_end(&cursor);
write_seqcount_begin(&dst->seq);
excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
write_seqcount_end(&dst->seq);
dma_resv_list_free(list);
dma_fence_put(excl);
return 0;
}
EXPORT_SYMBOL(dma_resv_copy_fences);
/**
* dma_resv_get_fences - Get an object's shared and exclusive
* dma_resv_get_fences - Get an object's fences
* fences without update side lock held
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
@ -649,7 +579,7 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
while (*num_fences)
dma_fence_put((*fences)[--(*num_fences)]);
count = cursor.shared_count + 1;
count = cursor.num_fences + 1;
/* Eventually re-allocate the array */
*fences = krealloc_array(*fences, count,
@ -723,8 +653,7 @@ int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
/**
* dma_resv_wait_timeout - Wait on reservation's objects
* shared and/or exclusive fences.
* dma_resv_wait_timeout - Wait on reservation's objects fences
* @obj: the reservation object
* @usage: controls which fences to include, see enum dma_resv_usage.
* @intr: if true, do interruptible wait

1
drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
View file

@ -34,7 +34,6 @@ struct amdgpu_fpriv;
struct amdgpu_bo_list_entry {
struct ttm_validate_buffer tv;
struct amdgpu_bo_va *bo_va;
struct dma_fence_chain *chain;
uint32_t priority;
struct page **user_pages;
bool user_invalidated;

53
drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
View file

@ -574,14 +574,6 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
e->bo_va = amdgpu_vm_bo_find(vm, bo);
if (bo->tbo.base.dma_buf && !amdgpu_bo_explicit_sync(bo)) {
e->chain = dma_fence_chain_alloc();
if (!e->chain) {
r = -ENOMEM;
goto error_validate;
}
}
}
/* Move fence waiting after getting reservation lock of
@ -642,13 +634,8 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
}
error_validate:
if (r) {
amdgpu_bo_list_for_each_entry(e, p->bo_list) {
dma_fence_chain_free(e->chain);
e->chain = NULL;
}
if (r)
ttm_eu_backoff_reservation(&p->ticket, &p->validated);
}
out:
return r;
}
@ -688,17 +675,9 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, int error,
{
unsigned i;
if (error && backoff) {
struct amdgpu_bo_list_entry *e;
amdgpu_bo_list_for_each_entry(e, parser->bo_list) {
dma_fence_chain_free(e->chain);
e->chain = NULL;
}
if (error && backoff)
ttm_eu_backoff_reservation(&parser->ticket,
&parser->validated);
}
for (i = 0; i < parser->num_post_deps; i++) {
drm_syncobj_put(parser->post_deps[i].syncobj);
@ -1272,31 +1251,9 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
amdgpu_vm_move_to_lru_tail(p->adev, &fpriv->vm);
amdgpu_bo_list_for_each_entry(e, p->bo_list) {
struct dma_resv *resv = e->tv.bo->base.resv;
struct dma_fence_chain *chain = e->chain;
struct dma_resv_iter cursor;
struct dma_fence *fence;
if (!chain)
continue;
/*
* Temporary workaround dma_resv shortcommings by wrapping up
* the submission in a dma_fence_chain and add it as exclusive
* fence.
*
* TODO: Remove together with dma_resv rework.
*/
dma_resv_for_each_fence(&cursor, resv,
DMA_RESV_USAGE_WRITE,
fence) {
break;
}
dma_fence_chain_init(chain, fence, dma_fence_get(p->fence), 1);
rcu_assign_pointer(resv->fence_excl, &chain->base);
e->chain = NULL;
}
/* Make sure all BOs are remembered as writers */
amdgpu_bo_list_for_each_entry(e, p->bo_list)
e->tv.num_shared = 0;
ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
mutex_unlock(&p->adev->notifier_lock);

47
include/linux/dma-resv.h
View file

@ -99,8 +99,8 @@ static inline enum dma_resv_usage dma_resv_usage_rw(bool write)
/**
* struct dma_resv - a reservation object manages fences for a buffer
*
* There are multiple uses for this, with sometimes slightly different rules in
* how the fence slots are used.
* This is a container for dma_fence objects which needs to handle multiple use
* cases.
*
* One use is to synchronize cross-driver access to a struct dma_buf, either for
* dynamic buffer management or just to handle implicit synchronization between
@ -130,47 +130,22 @@ struct dma_resv {
* @seq:
*
* Sequence count for managing RCU read-side synchronization, allows
* read-only access to @fence_excl and @fence while ensuring we take a
* consistent snapshot.
* read-only access to @fences while ensuring we take a consistent
* snapshot.
*/
seqcount_ww_mutex_t seq;
/**
* @fence_excl:
* @fences:
*
* The exclusive fence, if there is one currently.
* Array of fences which where added to the dma_resv object
*
* To guarantee that no fences are lost, this new fence must signal
* only after the previous exclusive fence has signalled. If
* semantically only a new access is added without actually treating the
* previous one as a dependency the exclusive fences can be strung
* together using struct dma_fence_chain.
*
* Note that actual semantics of what an exclusive or shared fence mean
* is defined by the user, for reservation objects shared across drivers
* see &dma_buf.resv.
*/
struct dma_fence __rcu *fence_excl;
/**
* @fence:
*
* List of current shared fences.
*
* There are no ordering constraints of shared fences against the
* exclusive fence slot. If a waiter needs to wait for all access, it
* has to wait for both sets of fences to signal.
*
* A new fence is added by calling dma_resv_add_shared_fence(). Since
* this often needs to be done past the point of no return in command
* A new fence is added by calling dma_resv_add_fence(). Since this
* often needs to be done past the point of no return in command
* submission it cannot fail, and therefore sufficient slots need to be
* reserved by calling dma_resv_reserve_fences().
*
* Note that actual semantics of what an exclusive or shared fence mean
* is defined by the user, for reservation objects shared across drivers
* see &dma_buf.resv.
*/
struct dma_resv_list __rcu *fence;
struct dma_resv_list __rcu *fences;
};
/**
@ -207,8 +182,8 @@ struct dma_resv_iter {
/** @fences: the shared fences; private, *MUST* not dereference */
struct dma_resv_list *fences;
/** @shared_count: number of shared fences */
unsigned int shared_count;
/** @num_fences: number of fences */
unsigned int num_fences;
/** @is_restarted: true if this is the first returned fence */
bool is_restarted;