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dma-buf: add new dma_fence_chain container v7

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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
This commit is contained in:
Christian König
2019-04-01 17:50:55 +08:00
committed by Christian König
parent 64e1f830ea
commit 7bf60c52e0
3 changed files with 324 additions and 1 deletions
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81
include/linux/dma-fence-chain.h Normal file
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/*
* fence-chain: chain fences together in a timeline
*
* Copyright (C) 2018 Advanced Micro Devices, Inc.
* Authors:
* Christian König <christian.koenig@amd.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#ifndef __LINUX_DMA_FENCE_CHAIN_H
#define __LINUX_DMA_FENCE_CHAIN_H
#include <linux/dma-fence.h>
#include <linux/irq_work.h>
/**
* struct dma_fence_chain - fence to represent an node of a fence chain
* @base: fence base class
* @lock: spinlock for fence handling
* @prev: previous fence of the chain
* @prev_seqno: original previous seqno before garbage collection
* @fence: encapsulated fence
* @cb: callback structure for signaling
* @work: irq work item for signaling
*/
struct dma_fence_chain {
struct dma_fence base;
spinlock_t lock;
struct dma_fence __rcu *prev;
u64 prev_seqno;
struct dma_fence *fence;
struct dma_fence_cb cb;
struct irq_work work;
};
extern const struct dma_fence_ops dma_fence_chain_ops;
/**
* 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 || fence->ops != &dma_fence_chain_ops)
return NULL;
return container_of(fence, struct dma_fence_chain, base);
}
/**
* 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.
*/
#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 */