// SPDX-License-Identifier: MIT
/*
* Copyright © 2021 Intel Corporation
*/
#include <linux/dma-fence.h>
#include <linux/slab.h>
#include <drm/ttm/ttm_bo.h>
#include "i915_deps.h"
/**
* DOC: Set of utilities to dynamically collect dependencies into a
* structure which is fed into the GT migration code.
*
* Once we can do async unbinding, this is also needed to coalesce
* the migration fence with the unbind fences if these are coalesced
* post-migration.
*
* While collecting the individual dependencies, we store the refcounted
* struct dma_fence pointers in a realloc-managed pointer array, since
* that can be easily fed into a dma_fence_array. Other options are
* available, like for example an xarray for similarity with drm/sched.
* Can be changed easily if needed.
*
* A struct i915_deps need to be initialized using i915_deps_init().
* If i915_deps_add_dependency() or i915_deps_add_resv() return an
* error code they will internally call i915_deps_fini(), which frees
* all internal references and allocations.
*/
/* Min number of fence pointers in the array when an allocation occurs. */
#define I915_DEPS_MIN_ALLOC_CHUNK 8U
static void i915_deps_reset_fences(struct i915_deps *deps)
{
if (deps->fences != &deps->single)
kfree(deps->fences);
deps->num_deps = 0;
deps->fences_size = 1;
deps->fences = &deps->single;
}
/**
* i915_deps_init - Initialize an i915_deps structure
* @deps: Pointer to the i915_deps structure to initialize.
* @gfp: The allocation mode for subsequenst allocations.
*/
void i915_deps_init(struct i915_deps *deps, gfp_t gfp)
{
deps->fences = NULL;
deps->gfp = gfp;
i915_deps_reset_fences(deps);
}
/**
* i915_deps_fini - Finalize an i915_deps structure
* @deps: Pointer to the i915_deps structure to finalize.
*
* This function drops all fence references taken, conditionally frees and
* then resets the fences array.
*/
void i915_deps_fini(struct i915_deps *deps)
{
unsigned int i;
for (i = 0; i < deps->num_deps; ++i)
dma_fence_put(deps->fences[i]);
if (deps->fences != &deps->single)
kfree(deps->fences);
}
static int i915_deps_grow(struct i915_deps *deps, struct dma_fence *fence,
const struct ttm_operation_ctx *ctx)
{
int ret;
if (deps->num_deps >= deps->fences_size) {
unsigned int new_size = 2 * deps->fences_size;
struct dma_fence **new_fences;
new_size = max(new_size, I915_DEPS_MIN_ALLOC_CHUNK);
new_fences = kmalloc_array(new_size, sizeof(*new_fences), deps->gfp);
if (!new_fences)
goto sync;
memcpy(new_fences, deps->fences,
deps->fences_size * sizeof(*new_fences));
swap(new_fences, deps->fences);
if (new_fences != &deps->single)
kfree(new_fences);
deps->fences_size = new_size;
}
deps->fences[deps->num_deps++] = dma_fence_get(fence);
return 0;
sync:
if (ctx->no_wait_gpu && !dma_fence_is_signaled(fence)) {
ret = -EBUSY;
goto unref;
}
ret = dma_fence_wait(fence, ctx->interruptible);
if (ret)
goto unref;
ret = fence->error;
if (ret)
goto unref;
return 0;
unref:
i915_deps_fini(deps);
return ret;
}
/**
* i915_deps_sync - Wait for all the fences in the dependency collection
* @deps: Pointer to the i915_deps structure the fences of which to wait for.
* @ctx: Pointer to a struct ttm_operation_ctx indicating how the waits
* should be performed.
*
* This function waits for fences in the dependency collection. If it
* encounters an error during the wait or a fence error, the wait for
* further fences is aborted and the error returned.
*
* Return: Zero if successful, Negative error code on error.
*/
int i915_deps_sync(const struct i915_deps *deps, const struct ttm_operation_ctx *ctx)
{
struct dma_fence **fences = deps->fences;
unsigned int i;
int ret = 0;
for (i = 0; i < deps->num_deps; ++i, ++fences) {
if (ctx->no_wait_gpu && !dma_fence_is_signaled(*fences)) {
ret = -EBUSY;
break;
}
ret = dma_fence_wait(*fences, ctx->interruptible);
if (!ret)
ret = (*fences)->error;
if (ret)
break;
}
return ret;
}
/**
* i915_deps_add_dependency - Add a fence to the dependency collection
* @deps: Pointer to the i915_deps structure a fence is to be added to.
* @fence: The fence to add.
* @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
* be performed if waiting.
*
* Adds a fence to the dependency collection, and takes a reference on it.
* If the fence context is not zero and there was a later fence from the
* same fence context already added, then the fence is not added to the
* dependency collection. If the fence context is not zero and there was
* an earlier fence already added, then the fence will replace the older
* fence from the same context and the reference on the earlier fence will
* be dropped.
* If there is a failure to allocate memory to accommodate the new fence to
* be added, the new fence will instead be waited for and an error may
* be returned; depending on the value of @ctx, or if there was a fence
* error. If an error was returned, the dependency collection will be
* finalized and all fence reference dropped.
*
* Return: 0 if success. Negative error code on error.
*/
int i915_deps_add_dependency(struct i915_deps *deps,
struct dma_fence *fence,
const struct ttm_operation_ctx *ctx)
{
unsigned int i;
int ret;
if (!fence)
return 0;
if (dma_fence_is_signaled(fence)) {
ret = fence->error;
if (ret)
i915_deps_fini(deps);
return ret;
}
for (i = 0; i < deps->num_deps; ++i) {
struct dma_fence *entry = deps->fences[i];
if (!entry->context || entry->context != fence->context)
continue;
if (dma_fence_is_later(fence, entry)) {
dma_fence_put(entry);
deps->fences[i] = dma_fence_get(fence);
}
return 0;
}
return i915_deps_grow(deps, fence, ctx);
}
/**
* i915_deps_add_resv - Add the fences of a reservation object to a dependency
* collection.
* @deps: Pointer to the i915_deps structure a fence is to be added to.
* @resv: The reservation object, then fences of which to add.
* @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
* be performed if waiting.
*
* Calls i915_deps_add_depencency() on the indicated fences of @resv.
*
* Return: Zero on success. Negative error code on error.
*/
int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,
const struct ttm_operation_ctx *ctx)
{
struct dma_resv_iter iter;
struct dma_fence *fence;
dma_resv_assert_held(resv);
dma_resv_for_each_fence(&iter, resv, dma_resv_usage_rw(true), fence) {
int ret = i915_deps_add_dependency(deps, fence, ctx);
if (ret)
return ret;
}
return 0;
}
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