2019-05-27 06:55:21 +00:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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2016-10-25 12:00:45 +00:00
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/*
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* fence-array: aggregates fence to be waited together
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*
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* Copyright (C) 2016 Collabora Ltd
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* Copyright (C) 2016 Advanced Micro Devices, Inc.
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* Authors:
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* Gustavo Padovan <gustavo@padovan.org>
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* Christian König <christian.koenig@amd.com>
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*/
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#ifndef __LINUX_DMA_FENCE_ARRAY_H
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#define __LINUX_DMA_FENCE_ARRAY_H
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#include <linux/dma-fence.h>
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dma-buf/fence: Fix lock inversion within dma-fence-array
Ages ago Rob Clark noted,
"Currently with fence-array, we have a potential deadlock situation. If
we fence_add_callback() on an array-fence, the array-fence's lock is
acquired first, and in it's ->enable_signaling() callback, it will install
cbs on it's array-member fences, so the array-member's lock is acquired
second.
But in the signal path, the array-member's lock is acquired first, and
the array-fence's lock acquired second."
Rob proposed either extensive changes to dma-fence to unnest the
fence-array signaling, or to defer the signaling onto a workqueue. This
is a more refined version of the later, that should keep the latency
of the fence signaling to a minimum by using an irq-work, which is
executed asap.
Reported-by: Rob Clark <robdclark@gmail.com>
Suggested-by: Rob Clark <robdclark@gmail.com>
References: 1476635975-21981-1-git-send-email-robdclark@gmail.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171114162719.30958-1-chris@chris-wilson.co.uk
2017-11-14 16:27:19 +00:00
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#include <linux/irq_work.h>
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2016-10-25 12:00:45 +00:00
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/**
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* struct dma_fence_array_cb - callback helper for fence array
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* @cb: fence callback structure for signaling
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* @array: reference to the parent fence array object
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*/
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struct dma_fence_array_cb {
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struct dma_fence_cb cb;
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struct dma_fence_array *array;
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};
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/**
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* struct dma_fence_array - fence to represent an array of fences
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* @base: fence base class
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* @lock: spinlock for fence handling
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* @num_fences: number of fences in the array
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* @num_pending: fences in the array still pending
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* @fences: array of the fences
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2019-01-16 22:34:36 +00:00
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* @work: internal irq_work function
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2016-10-25 12:00:45 +00:00
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*/
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struct dma_fence_array {
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struct dma_fence base;
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spinlock_t lock;
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unsigned num_fences;
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atomic_t num_pending;
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struct dma_fence **fences;
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dma-buf/fence: Fix lock inversion within dma-fence-array
Ages ago Rob Clark noted,
"Currently with fence-array, we have a potential deadlock situation. If
we fence_add_callback() on an array-fence, the array-fence's lock is
acquired first, and in it's ->enable_signaling() callback, it will install
cbs on it's array-member fences, so the array-member's lock is acquired
second.
But in the signal path, the array-member's lock is acquired first, and
the array-fence's lock acquired second."
Rob proposed either extensive changes to dma-fence to unnest the
fence-array signaling, or to defer the signaling onto a workqueue. This
is a more refined version of the later, that should keep the latency
of the fence signaling to a minimum by using an irq-work, which is
executed asap.
Reported-by: Rob Clark <robdclark@gmail.com>
Suggested-by: Rob Clark <robdclark@gmail.com>
References: 1476635975-21981-1-git-send-email-robdclark@gmail.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171114162719.30958-1-chris@chris-wilson.co.uk
2017-11-14 16:27:19 +00:00
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struct irq_work work;
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2016-10-25 12:00:45 +00:00
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};
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/**
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* to_dma_fence_array - cast a fence to a dma_fence_array
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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_array,
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* or the dma_fence_array otherwise.
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*/
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static inline struct dma_fence_array *
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to_dma_fence_array(struct dma_fence *fence)
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{
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2022-01-19 10:17:32 +00:00
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if (!fence || !dma_fence_is_array(fence))
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2016-10-25 12:00:45 +00:00
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return NULL;
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return container_of(fence, struct dma_fence_array, base);
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}
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2022-01-24 13:03:24 +00:00
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/**
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* dma_fence_array_for_each - iterate over all fences in array
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* @fence: current fence
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* @index: index into the array
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* @head: potential dma_fence_array object
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*
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* Test if @array is a dma_fence_array object and if yes iterate over all fences
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* in the array. If not just iterate over the fence in @array itself.
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2022-03-11 09:27:53 +00:00
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*
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* For a deep dive iterator see dma_fence_unwrap_for_each().
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2022-01-24 13:03:24 +00:00
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*/
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#define dma_fence_array_for_each(fence, index, head) \
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for (index = 0, fence = dma_fence_array_first(head); fence; \
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++(index), fence = dma_fence_array_next(head, index))
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2016-10-25 12:00:45 +00:00
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struct dma_fence_array *dma_fence_array_create(int num_fences,
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struct dma_fence **fences,
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u64 context, unsigned seqno,
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bool signal_on_any);
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2017-03-17 16:34:49 +00:00
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bool dma_fence_match_context(struct dma_fence *fence, u64 context);
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2022-01-24 13:03:24 +00:00
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struct dma_fence *dma_fence_array_first(struct dma_fence *head);
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struct dma_fence *dma_fence_array_next(struct dma_fence *head,
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unsigned int index);
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2016-10-25 12:00:45 +00:00
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#endif /* __LINUX_DMA_FENCE_ARRAY_H */
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