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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* fence-chain: chain fences together in a timeline
*
* Copyright (C) 2018 Advanced Micro Devices, Inc.
* Authors:
* Christian König <christian.koenig@amd.com>
*/
#ifndef __LINUX_DMA_FENCE_CHAIN_H
#define __LINUX_DMA_FENCE_CHAIN_H
#include <linux/dma-fence.h>
#include <linux/irq_work.h>
#include <linux/slab.h>
/**
* struct dma_fence_chain - fence to represent an node of a fence chain
* @base: fence base class
* @prev: previous fence of the chain
* @prev_seqno: original previous seqno before garbage collection
* @fence: encapsulated fence
* @lock: spinlock for fence handling
*/
struct dma_fence_chain {
struct dma_fence base;
struct dma_fence __rcu *prev;
u64 prev_seqno;
struct dma_fence *fence;
union {
/**
* @cb: callback for signaling
*
* This is used to add the callback for signaling the
* complection of the fence chain. Never used at the same time
* as the irq work.
*/
struct dma_fence_cb cb;
/**
* @work: irq work item for signaling
*
* Irq work structure to allow us to add the callback without
* running into lock inversion. Never used at the same time as
* the callback.
*/
struct irq_work work;
};
spinlock_t lock;
};
/**
* to_dma_fence_chain - cast a fence to a dma_fence_chain
* @fence: fence to cast to a dma_fence_array
*
* Returns NULL if the fence is not a dma_fence_chain,
* or the dma_fence_chain otherwise.
*/
static inline struct dma_fence_chain *
to_dma_fence_chain(struct dma_fence *fence)
{
if (!fence || !dma_fence_is_chain(fence))
return NULL;
return container_of(fence, struct dma_fence_chain, base);
}
/**
* dma_fence_chain_contained - return the contained fence
* @fence: the fence to test
*
* If the fence is a dma_fence_chain the function returns the fence contained
* inside the chain object, otherwise it returns the fence itself.
*/
static inline struct dma_fence *
dma_fence_chain_contained(struct dma_fence *fence)
{
struct dma_fence_chain *chain = to_dma_fence_chain(fence);
return chain ? chain->fence : fence;
}
/**
* dma_fence_chain_alloc
*
* Returns a new struct dma_fence_chain object or NULL on failure.
*/
static inline struct dma_fence_chain *dma_fence_chain_alloc(void)
{
return kmalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
};
/**
* dma_fence_chain_free
* @chain: chain node to free
*
* Frees up an allocated but not used struct dma_fence_chain object. This
* doesn't need an RCU grace period since the fence was never initialized nor
* published. After dma_fence_chain_init() has been called the fence must be
* released by calling dma_fence_put(), and not through this function.
*/
static inline void dma_fence_chain_free(struct dma_fence_chain *chain)
{
kfree(chain);
};
/**
* dma_fence_chain_for_each - iterate over all fences in chain
* @iter: current fence
* @head: starting point
*
* Iterate over all fences in the chain. We keep a reference to the current
* fence while inside the loop which must be dropped when breaking out.
*
* For a deep dive iterator see dma_fence_unwrap_for_each().
*/
#define dma_fence_chain_for_each(iter, head) \
for (iter = dma_fence_get(head); iter; \
iter = dma_fence_chain_walk(iter))
struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
void dma_fence_chain_init(struct dma_fence_chain *chain,
struct dma_fence *prev,
struct dma_fence *fence,
uint64_t seqno);
#endif /* __LINUX_DMA_FENCE_CHAIN_H */
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