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7bf60c52e0
Lockless container implementation similar to a dma_fence_array, but with
only two elements per node and automatic garbage collection.
v2: properly document dma_fence_chain_for_each, add dma_fence_chain_find_seqno,
drop prev reference during garbage collection if it's not a chain fence.
v3: use head and iterator for dma_fence_chain_for_each
v4: fix reference count in dma_fence_chain_enable_signaling
v5: fix iteration when walking each chain node
v6: add __rcu for member 'prev' of struct chain node
v7: fix rcu warnings from kernel robot
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/295778/?series=58813&rev=1
82 lines
2.4 KiB
C
82 lines
2.4 KiB
C
/*
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* fence-chain: chain fences together in a timeline
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*
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* Copyright (C) 2018 Advanced Micro Devices, Inc.
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* Authors:
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* Christian König <christian.koenig@amd.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#ifndef __LINUX_DMA_FENCE_CHAIN_H
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#define __LINUX_DMA_FENCE_CHAIN_H
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#include <linux/dma-fence.h>
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#include <linux/irq_work.h>
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/**
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* struct dma_fence_chain - fence to represent an node of a fence chain
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* @base: fence base class
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* @lock: spinlock for fence handling
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* @prev: previous fence of the chain
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* @prev_seqno: original previous seqno before garbage collection
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* @fence: encapsulated fence
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* @cb: callback structure for signaling
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* @work: irq work item for signaling
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*/
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struct dma_fence_chain {
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struct dma_fence base;
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spinlock_t lock;
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struct dma_fence __rcu *prev;
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u64 prev_seqno;
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struct dma_fence *fence;
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struct dma_fence_cb cb;
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struct irq_work work;
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};
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extern const struct dma_fence_ops dma_fence_chain_ops;
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/**
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* to_dma_fence_chain - cast a fence to a dma_fence_chain
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* @fence: fence to cast to a dma_fence_array
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*
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* Returns NULL if the fence is not a dma_fence_chain,
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* or the dma_fence_chain otherwise.
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*/
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static inline struct dma_fence_chain *
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to_dma_fence_chain(struct dma_fence *fence)
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{
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if (!fence || fence->ops != &dma_fence_chain_ops)
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return NULL;
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return container_of(fence, struct dma_fence_chain, base);
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}
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/**
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* dma_fence_chain_for_each - iterate over all fences in chain
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* @iter: current fence
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* @head: starting point
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*
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* Iterate over all fences in the chain. We keep a reference to the current
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* fence while inside the loop which must be dropped when breaking out.
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*/
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#define dma_fence_chain_for_each(iter, head) \
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for (iter = dma_fence_get(head); iter; \
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iter = dma_fence_chain_walk(iter))
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struct dma_fence *dma_fence_chain_walk(struct dma_fence *fence);
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int dma_fence_chain_find_seqno(struct dma_fence **pfence, uint64_t seqno);
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void dma_fence_chain_init(struct dma_fence_chain *chain,
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struct dma_fence *prev,
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struct dma_fence *fence,
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uint64_t seqno);
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#endif /* __LINUX_DMA_FENCE_CHAIN_H */
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