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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>
#include <linux/sort.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);
static int fence_cmp(const void *_a, const void *_b)
{
struct dma_fence *a = *(struct dma_fence **)_a;
struct dma_fence *b = *(struct dma_fence **)_b;
if (a->context < b->context)
return -1;
else if (a->context > b->context)
return 1;
if (dma_fence_is_later(b, a))
return 1;
else if (dma_fence_is_later(a, b))
return -1;
return 0;
}
/**
* dma_fence_dedup_array - Sort and deduplicate an array of dma_fence pointers
* @fences: Array of dma_fence pointers to be deduplicated
* @num_fences: Number of entries in the @fences array
*
* Sorts the input array by context, then removes duplicate
* fences with the same context, keeping only the most recent one.
*
* The array is modified in-place and unreferenced duplicate fences are released
* via dma_fence_put(). The function returns the new number of fences after
* deduplication.
*
* Return: Number of unique fences remaining in the array.
*/
int dma_fence_dedup_array(struct dma_fence **fences, int num_fences)
{
int i, j;
sort(fences, num_fences, sizeof(*fences), fence_cmp, NULL);
/*
* Only keep the most recent fence for each context.
*/
j = 0;
for (i = 1; i < num_fences; i++) {
if (fences[i]->context == fences[j]->context)
dma_fence_put(fences[i]);
else
fences[++j] = fences[i];
}
return ++j;
}
EXPORT_SYMBOL_GPL(dma_fence_dedup_array);
/* 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 *tmp, *unsignaled = NULL, **array;
struct dma_fence_array *result;
ktime_t timestamp;
int i, 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)) {
dma_fence_put(unsignaled);
unsignaled = dma_fence_get(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.
*
* Or if there was a single unsignaled fence left we can return it
* directly and early since that is a major path on many workloads.
*/
if (count == 0)
return dma_fence_allocate_private_stub(timestamp);
else if (count == 1)
return unsignaled;
dma_fence_put(unsignaled);
array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
if (!array)
return NULL;
count = 0;
for (i = 0; i < num_fences; ++i) {
dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
if (!dma_fence_is_signaled(tmp)) {
array[count++] = dma_fence_get(tmp);
} else {
ktime_t t = dma_fence_timestamp(tmp);
if (ktime_after(t, timestamp))
timestamp = t;
}
}
}
if (count == 0 || count == 1)
goto return_fastpath;
count = dma_fence_dedup_array(array, count);
if (count > 1) {
result = dma_fence_array_create(count, array,
dma_fence_context_alloc(1),
1, false);
if (!result) {
for (i = 0; i < count; i++)
dma_fence_put(array[i]);
tmp = NULL;
goto return_tmp;
}
return &result->base;
}
return_fastpath:
if (count == 0)
tmp = dma_fence_allocate_private_stub(timestamp);
else
tmp = array[0];
return_tmp:
kfree(array);
return tmp;
}
EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge);
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