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// SPDX-License-Identifier: MIT
/*
* Copyright © 2021 Intel Corporation
*/
#include <linux/slab.h>
#include "i915_vma_resource.h"
/* Callbacks for the unbind dma-fence. */
static const char *get_driver_name(struct dma_fence *fence)
{
return "vma unbind fence";
}
static const char *get_timeline_name(struct dma_fence *fence)
{
return "unbound";
}
static struct dma_fence_ops unbind_fence_ops = {
.get_driver_name = get_driver_name,
.get_timeline_name = get_timeline_name,
};
/**
* i915_vma_resource_init - Initialize a vma resource.
* @vma_res: The vma resource to initialize
*
* Initializes a vma resource allocated using i915_vma_resource_alloc().
* The reason for having separate allocate and initialize function is that
* initialization may need to be performed from under a lock where
* allocation is not allowed.
*/
void i915_vma_resource_init(struct i915_vma_resource *vma_res)
{
spin_lock_init(&vma_res->lock);
dma_fence_init(&vma_res->unbind_fence, &unbind_fence_ops,
&vma_res->lock, 0, 0);
refcount_set(&vma_res->hold_count, 1);
}
/**
* i915_vma_resource_alloc - Allocate a vma resource
*
* Return: A pointer to a cleared struct i915_vma_resource or
* a -ENOMEM error pointer if allocation fails.
*/
struct i915_vma_resource *i915_vma_resource_alloc(void)
{
struct i915_vma_resource *vma_res =
kzalloc(sizeof(*vma_res), GFP_KERNEL);
return vma_res ? vma_res : ERR_PTR(-ENOMEM);
}
static void __i915_vma_resource_unhold(struct i915_vma_resource *vma_res)
{
if (refcount_dec_and_test(&vma_res->hold_count))
dma_fence_signal(&vma_res->unbind_fence);
}
/**
* i915_vma_resource_unhold - Unhold the signaling of the vma resource unbind
* fence.
* @vma_res: The vma resource.
* @lockdep_cookie: The lockdep cookie returned from i915_vma_resource_hold.
*
* The function may leave a dma_fence critical section.
*/
void i915_vma_resource_unhold(struct i915_vma_resource *vma_res,
bool lockdep_cookie)
{
dma_fence_end_signalling(lockdep_cookie);
if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
unsigned long irq_flags;
/* Inefficient open-coded might_lock_irqsave() */
spin_lock_irqsave(&vma_res->lock, irq_flags);
spin_unlock_irqrestore(&vma_res->lock, irq_flags);
}
__i915_vma_resource_unhold(vma_res);
}
/**
* i915_vma_resource_hold - Hold the signaling of the vma resource unbind fence.
* @vma_res: The vma resource.
* @lockdep_cookie: Pointer to a bool serving as a lockdep cooke that should
* be given as an argument to the pairing i915_vma_resource_unhold.
*
* If returning true, the function enters a dma_fence signalling critical
* section if not in one already.
*
* Return: true if holding successful, false if not.
*/
bool i915_vma_resource_hold(struct i915_vma_resource *vma_res,
bool *lockdep_cookie)
{
bool held = refcount_inc_not_zero(&vma_res->hold_count);
if (held)
*lockdep_cookie = dma_fence_begin_signalling();
return held;
}
/**
* i915_vma_resource_unbind - Unbind a vma resource
* @vma_res: The vma resource to unbind.
*
* At this point this function does little more than publish a fence that
* signals immediately unless signaling is held back.
*
* Return: A refcounted pointer to a dma-fence that signals when unbinding is
* complete.
*/
struct dma_fence *
i915_vma_resource_unbind(struct i915_vma_resource *vma_res)
{
__i915_vma_resource_unhold(vma_res);
dma_fence_get(&vma_res->unbind_fence);
return &vma_res->unbind_fence;
}
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