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// SPDX-License-Identifier: GPL-2.0-only
/*
* dma-fence-util: misc functions for dma_fence objects
*
* Copyright (C) 2022 Advanced Micro Devices, Inc.
* Authors:
* Christian König <christian.koenig@amd.com>
*/
#include <linux/dma-fence.h>
#include <linux/dma-fence-array.h>
#include <linux/dma-fence-chain.h>
#include <linux/dma-fence-unwrap.h>
#include <linux/slab.h>
/* Internal helper to start new array iteration, don't use directly */
static struct dma_fence *
__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor)
{
cursor->array = dma_fence_chain_contained(cursor->chain);
cursor->index = 0;
return dma_fence_array_first(cursor->array);
}
/**
* dma_fence_unwrap_first - return the first fence from fence containers
* @head: the entrypoint into the containers
* @cursor: current position inside the containers
*
* Unwraps potential dma_fence_chain/dma_fence_array containers and return the
* first fence.
*/
struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head,
struct dma_fence_unwrap *cursor)
{
cursor->chain = dma_fence_get(head);
return __dma_fence_unwrap_array(cursor);
}
EXPORT_SYMBOL_GPL(dma_fence_unwrap_first);
/**
* dma_fence_unwrap_next - return the next fence from a fence containers
* @cursor: current position inside the containers
*
* Continue unwrapping the dma_fence_chain/dma_fence_array containers and return
* the next fence from them.
*/
struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
{
struct dma_fence *tmp;
++cursor->index;
tmp = dma_fence_array_next(cursor->array, cursor->index);
if (tmp)
return tmp;
cursor->chain = dma_fence_chain_walk(cursor->chain);
return __dma_fence_unwrap_array(cursor);
}
EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
/* Implementation for the dma_fence_merge() marco, don't use directly */
struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
struct dma_fence **fences,
struct dma_fence_unwrap *iter)
{
struct dma_fence_array *result;
struct dma_fence *tmp, **array;
ktime_t timestamp;
unsigned int i;
size_t count;
count = 0;
timestamp = ns_to_ktime(0);
for (i = 0; i < num_fences; ++i) {
dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
if (!dma_fence_is_signaled(tmp)) {
++count;
} else {
ktime_t t = dma_fence_timestamp(tmp);
if (ktime_after(t, timestamp))
timestamp = t;
}
}
}
/*
* If we couldn't find a pending fence just return a private signaled
* fence with the timestamp of the last signaled one.
*/
if (count == 0)
return dma_fence_allocate_private_stub(timestamp);
array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
if (!array)
return NULL;
/*
* This trashes the input fence array and uses it as position for the
* following merge loop. This works because the dma_fence_merge()
* wrapper macro is creating this temporary array on the stack together
* with the iterators.
*/
for (i = 0; i < num_fences; ++i)
fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]);
count = 0;
do {
unsigned int sel;
restart:
tmp = NULL;
for (i = 0; i < num_fences; ++i) {
struct dma_fence *next;
while (fences[i] && dma_fence_is_signaled(fences[i]))
fences[i] = dma_fence_unwrap_next(&iter[i]);
next = fences[i];
if (!next)
continue;
/*
* We can't guarantee that inpute fences are ordered by
* context, but it is still quite likely when this
* function is used multiple times. So attempt to order
* the fences by context as we pass over them and merge
* fences with the same context.
*/
if (!tmp || tmp->context > next->context) {
tmp = next;
sel = i;
} else if (tmp->context < next->context) {
continue;
} else if (dma_fence_is_later(tmp, next)) {
fences[i] = dma_fence_unwrap_next(&iter[i]);
goto restart;
} else {
fences[sel] = dma_fence_unwrap_next(&iter[sel]);
goto restart;
}
}
if (tmp) {
array[count++] = dma_fence_get(tmp);
fences[sel] = dma_fence_unwrap_next(&iter[sel]);
}
} while (tmp);
if (count == 0) {
tmp = dma_fence_allocate_private_stub(ktime_get());
goto return_tmp;
}
if (count == 1) {
tmp = array[0];
goto return_tmp;
}
result = dma_fence_array_create(count, array,
dma_fence_context_alloc(1),
1, false);
if (!result) {
tmp = NULL;
goto return_tmp;
}
return &result->base;
return_tmp:
kfree(array);
return tmp;
}
EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
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