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path: root/drivers/dma-buf/dma-resv.c
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Diffstat (limited to 'drivers/dma-buf/dma-resv.c')
-rw-r--r--drivers/dma-buf/dma-resv.c353
1 files changed, 141 insertions, 212 deletions
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 543dae6566d2..378d47e1cfea 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -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)
-{
- 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)
+/* 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, 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