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475 lines
16 KiB
475 lines
16 KiB
/* |
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* Header file for reservations for dma-buf and ttm |
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* |
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* Copyright(C) 2011 Linaro Limited. All rights reserved. |
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* Copyright (C) 2012-2013 Canonical Ltd |
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* Copyright (C) 2012 Texas Instruments |
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* |
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* Authors: |
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* Rob Clark <[email protected]> |
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* Maarten Lankhorst <[email protected]> |
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* Thomas Hellstrom <thellstrom-at-vmware-dot-com> |
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* |
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* Based on bo.c which bears the following copyright notice, |
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* but is dual licensed: |
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* |
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* Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA |
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* All Rights Reserved. |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a |
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* copy of this software and associated documentation files (the |
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* "Software"), to deal in the Software without restriction, including |
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* without limitation the rights to use, copy, modify, merge, publish, |
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* distribute, sub license, and/or sell copies of the Software, and to |
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* permit persons to whom the Software is furnished to do so, subject to |
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* the following conditions: |
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* |
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* The above copyright notice and this permission notice (including the |
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* next paragraph) shall be included in all copies or substantial portions |
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* of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL |
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* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, |
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
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* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE |
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* USE OR OTHER DEALINGS IN THE SOFTWARE. |
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*/ |
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#ifndef _LINUX_RESERVATION_H |
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#define _LINUX_RESERVATION_H |
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#include <linux/ww_mutex.h> |
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#include <linux/dma-fence.h> |
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#include <linux/slab.h> |
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#include <linux/seqlock.h> |
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#include <linux/rcupdate.h> |
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extern struct ww_class reservation_ww_class; |
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struct dma_resv_list; |
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/** |
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* enum dma_resv_usage - how the fences from a dma_resv obj are used |
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* |
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* This enum describes the different use cases for a dma_resv object and |
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* controls which fences are returned when queried. |
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* |
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* An important fact is that there is the order KERNEL<WRITE<READ<BOOKKEEP and |
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* when the dma_resv object is asked for fences for one use case the fences |
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* for the lower use case are returned as well. |
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* |
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* For example when asking for WRITE fences then the KERNEL fences are returned |
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* as well. Similar when asked for READ fences then both WRITE and KERNEL |
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* fences are returned as well. |
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*/ |
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enum dma_resv_usage { |
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/** |
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* @DMA_RESV_USAGE_KERNEL: For in kernel memory management only. |
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* |
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* This should only be used for things like copying or clearing memory |
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* with a DMA hardware engine for the purpose of kernel memory |
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* management. |
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* |
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* Drivers *always* must wait for those fences before accessing the |
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* resource protected by the dma_resv object. The only exception for |
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* that is when the resource is known to be locked down in place by |
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* pinning it previously. |
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*/ |
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DMA_RESV_USAGE_KERNEL, |
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/** |
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* @DMA_RESV_USAGE_WRITE: Implicit write synchronization. |
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* |
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* This should only be used for userspace command submissions which add |
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* an implicit write dependency. |
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*/ |
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DMA_RESV_USAGE_WRITE, |
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/** |
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* @DMA_RESV_USAGE_READ: Implicit read synchronization. |
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* |
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* This should only be used for userspace command submissions which add |
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* an implicit read dependency. |
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*/ |
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DMA_RESV_USAGE_READ, |
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/** |
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* @DMA_RESV_USAGE_BOOKKEEP: No implicit sync. |
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* |
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* This should be used by submissions which don't want to participate in |
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* implicit synchronization. |
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* |
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* The most common case are preemption fences as well as page table |
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* updates and their TLB flushes. |
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*/ |
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DMA_RESV_USAGE_BOOKKEEP |
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}; |
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/** |
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* dma_resv_usage_rw - helper for implicit sync |
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* @write: true if we create a new implicit sync write |
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* |
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* This returns the implicit synchronization usage for write or read accesses, |
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* see enum dma_resv_usage and &dma_buf.resv. |
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*/ |
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static inline enum dma_resv_usage dma_resv_usage_rw(bool write) |
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{ |
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/* This looks confusing at first sight, but is indeed correct. |
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* |
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* The rational is that new write operations needs to wait for the |
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* existing read and write operations to finish. |
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* But a new read operation only needs to wait for the existing write |
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* operations to finish. |
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*/ |
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return write ? DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE; |
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} |
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/** |
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* struct dma_resv - a reservation object manages fences for a buffer |
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* |
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* This is a container for dma_fence objects which needs to handle multiple use |
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* cases. |
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* |
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* One use is to synchronize cross-driver access to a struct dma_buf, either for |
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* dynamic buffer management or just to handle implicit synchronization between |
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* different users of the buffer in userspace. See &dma_buf.resv for a more |
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* in-depth discussion. |
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* |
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* The other major use is to manage access and locking within a driver in a |
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* buffer based memory manager. struct ttm_buffer_object is the canonical |
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* example here, since this is where reservation objects originated from. But |
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* use in drivers is spreading and some drivers also manage struct |
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* drm_gem_object with the same scheme. |
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*/ |
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struct dma_resv { |
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/** |
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* @lock: |
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* |
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* Update side lock. Don't use directly, instead use the wrapper |
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* functions like dma_resv_lock() and dma_resv_unlock(). |
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* |
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* Drivers which use the reservation object to manage memory dynamically |
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* also use this lock to protect buffer object state like placement, |
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* allocation policies or throughout command submission. |
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*/ |
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struct ww_mutex lock; |
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/** |
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* @fences: |
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* |
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* Array of fences which where added to the dma_resv object |
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* |
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* A new fence is added by calling dma_resv_add_fence(). Since this |
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* often needs to be done past the point of no return in command |
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* submission it cannot fail, and therefore sufficient slots need to be |
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* reserved by calling dma_resv_reserve_fences(). |
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*/ |
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struct dma_resv_list __rcu *fences; |
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}; |
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/** |
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* struct dma_resv_iter - current position into the dma_resv fences |
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* |
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* Don't touch this directly in the driver, use the accessor function instead. |
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* |
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* IMPORTANT |
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* |
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* When using the lockless iterators like dma_resv_iter_next_unlocked() or |
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* dma_resv_for_each_fence_unlocked() beware that the iterator can be restarted. |
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* Code which accumulates statistics or similar needs to check for this with |
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* dma_resv_iter_is_restarted(). |
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*/ |
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struct dma_resv_iter { |
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/** @obj: The dma_resv object we iterate over */ |
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struct dma_resv *obj; |
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/** @usage: Return fences with this usage or lower. */ |
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enum dma_resv_usage usage; |
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/** @fence: the currently handled fence */ |
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struct dma_fence *fence; |
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/** @fence_usage: the usage of the current fence */ |
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enum dma_resv_usage fence_usage; |
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/** @index: index into the shared fences */ |
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unsigned int index; |
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/** @fences: the shared fences; private, *MUST* not dereference */ |
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struct dma_resv_list *fences; |
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/** @num_fences: number of fences */ |
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unsigned int num_fences; |
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/** @is_restarted: true if this is the first returned fence */ |
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bool is_restarted; |
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}; |
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struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor); |
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struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor); |
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struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor); |
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struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor); |
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/** |
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* dma_resv_iter_begin - initialize a dma_resv_iter object |
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* @cursor: The dma_resv_iter object to initialize |
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* @obj: The dma_resv object which we want to iterate over |
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* @usage: controls which fences to include, see enum dma_resv_usage. |
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*/ |
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static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor, |
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struct dma_resv *obj, |
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enum dma_resv_usage usage) |
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{ |
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cursor->obj = obj; |
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cursor->usage = usage; |
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cursor->fence = NULL; |
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} |
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/** |
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* dma_resv_iter_end - cleanup a dma_resv_iter object |
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* @cursor: the dma_resv_iter object which should be cleaned up |
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* |
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* Make sure that the reference to the fence in the cursor is properly |
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* dropped. |
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*/ |
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static inline void dma_resv_iter_end(struct dma_resv_iter *cursor) |
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{ |
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dma_fence_put(cursor->fence); |
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} |
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/** |
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* dma_resv_iter_usage - Return the usage of the current fence |
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* @cursor: the cursor of the current position |
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* |
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* Returns the usage of the currently processed fence. |
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*/ |
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static inline enum dma_resv_usage |
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dma_resv_iter_usage(struct dma_resv_iter *cursor) |
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{ |
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return cursor->fence_usage; |
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} |
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/** |
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* dma_resv_iter_is_restarted - test if this is the first fence after a restart |
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* @cursor: the cursor with the current position |
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* |
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* Return true if this is the first fence in an iteration after a restart. |
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*/ |
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static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor) |
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{ |
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return cursor->is_restarted; |
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} |
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/** |
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* dma_resv_for_each_fence_unlocked - unlocked fence iterator |
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* @cursor: a struct dma_resv_iter pointer |
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* @fence: the current fence |
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* |
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* Iterate over the fences in a struct dma_resv object without holding the |
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* &dma_resv.lock and using RCU instead. The cursor needs to be initialized |
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* with dma_resv_iter_begin() and cleaned up with dma_resv_iter_end(). Inside |
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* the iterator a reference to the dma_fence is held and the RCU lock dropped. |
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* |
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* Beware that the iterator can be restarted when the struct dma_resv for |
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* @cursor is modified. Code which accumulates statistics or similar needs to |
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* check for this with dma_resv_iter_is_restarted(). For this reason prefer the |
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* lock iterator dma_resv_for_each_fence() whenever possible. |
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*/ |
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#define dma_resv_for_each_fence_unlocked(cursor, fence) \ |
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for (fence = dma_resv_iter_first_unlocked(cursor); \ |
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fence; fence = dma_resv_iter_next_unlocked(cursor)) |
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/** |
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* dma_resv_for_each_fence - fence iterator |
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* @cursor: a struct dma_resv_iter pointer |
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* @obj: a dma_resv object pointer |
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* @usage: controls which fences to return |
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* @fence: the current fence |
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* |
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* Iterate over the fences in a struct dma_resv object while holding the |
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* &dma_resv.lock. @all_fences controls if the shared fences are returned as |
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* well. The cursor initialisation is part of the iterator and the fence stays |
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* valid as long as the lock is held and so no extra reference to the fence is |
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* taken. |
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*/ |
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#define dma_resv_for_each_fence(cursor, obj, usage, fence) \ |
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for (dma_resv_iter_begin(cursor, obj, usage), \ |
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fence = dma_resv_iter_first(cursor); fence; \ |
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fence = dma_resv_iter_next(cursor)) |
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#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base) |
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#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base) |
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#ifdef CONFIG_DEBUG_MUTEXES |
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void dma_resv_reset_max_fences(struct dma_resv *obj); |
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#else |
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static inline void dma_resv_reset_max_fences(struct dma_resv *obj) {} |
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#endif |
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/** |
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* dma_resv_lock - lock the reservation object |
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* @obj: the reservation object |
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* @ctx: the locking context |
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* |
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* Locks the reservation object for exclusive access and modification. Note, |
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* that the lock is only against other writers, readers will run concurrently |
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* with a writer under RCU. The seqlock is used to notify readers if they |
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* overlap with a writer. |
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* |
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* As the reservation object may be locked by multiple parties in an |
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* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle |
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* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation |
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* object may be locked by itself by passing NULL as @ctx. |
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* |
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* When a die situation is indicated by returning -EDEADLK all locks held by |
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* @ctx must be unlocked and then dma_resv_lock_slow() called on @obj. |
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* |
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* Unlocked by calling dma_resv_unlock(). |
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* |
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* See also dma_resv_lock_interruptible() for the interruptible variant. |
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*/ |
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static inline int dma_resv_lock(struct dma_resv *obj, |
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struct ww_acquire_ctx *ctx) |
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{ |
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return ww_mutex_lock(&obj->lock, ctx); |
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} |
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/** |
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* dma_resv_lock_interruptible - lock the reservation object |
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* @obj: the reservation object |
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* @ctx: the locking context |
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* |
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* Locks the reservation object interruptible for exclusive access and |
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* modification. Note, that the lock is only against other writers, readers |
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* will run concurrently with a writer under RCU. The seqlock is used to |
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* notify readers if they overlap with a writer. |
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* |
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* As the reservation object may be locked by multiple parties in an |
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* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle |
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* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation |
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* object may be locked by itself by passing NULL as @ctx. |
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* |
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* When a die situation is indicated by returning -EDEADLK all locks held by |
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* @ctx must be unlocked and then dma_resv_lock_slow_interruptible() called on |
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* @obj. |
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* |
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* Unlocked by calling dma_resv_unlock(). |
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*/ |
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static inline int dma_resv_lock_interruptible(struct dma_resv *obj, |
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struct ww_acquire_ctx *ctx) |
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{ |
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return ww_mutex_lock_interruptible(&obj->lock, ctx); |
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} |
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/** |
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* dma_resv_lock_slow - slowpath lock the reservation object |
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* @obj: the reservation object |
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* @ctx: the locking context |
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* |
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* Acquires the reservation object after a die case. This function |
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* will sleep until the lock becomes available. See dma_resv_lock() as |
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* well. |
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* |
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* See also dma_resv_lock_slow_interruptible() for the interruptible variant. |
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*/ |
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static inline void dma_resv_lock_slow(struct dma_resv *obj, |
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struct ww_acquire_ctx *ctx) |
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{ |
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ww_mutex_lock_slow(&obj->lock, ctx); |
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} |
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/** |
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* dma_resv_lock_slow_interruptible - slowpath lock the reservation |
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* object, interruptible |
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* @obj: the reservation object |
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* @ctx: the locking context |
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* |
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* Acquires the reservation object interruptible after a die case. This function |
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* will sleep until the lock becomes available. See |
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* dma_resv_lock_interruptible() as well. |
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*/ |
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static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj, |
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struct ww_acquire_ctx *ctx) |
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{ |
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return ww_mutex_lock_slow_interruptible(&obj->lock, ctx); |
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} |
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/** |
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* dma_resv_trylock - trylock the reservation object |
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* @obj: the reservation object |
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* |
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* Tries to lock the reservation object for exclusive access and modification. |
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* Note, that the lock is only against other writers, readers will run |
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* concurrently with a writer under RCU. The seqlock is used to notify readers |
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* if they overlap with a writer. |
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* |
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* Also note that since no context is provided, no deadlock protection is |
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* possible, which is also not needed for a trylock. |
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* |
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* Returns true if the lock was acquired, false otherwise. |
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*/ |
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static inline bool __must_check dma_resv_trylock(struct dma_resv *obj) |
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{ |
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return ww_mutex_trylock(&obj->lock, NULL); |
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} |
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/** |
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* dma_resv_is_locked - is the reservation object locked |
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* @obj: the reservation object |
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* |
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* Returns true if the mutex is locked, false if unlocked. |
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*/ |
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static inline bool dma_resv_is_locked(struct dma_resv *obj) |
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{ |
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return ww_mutex_is_locked(&obj->lock); |
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} |
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/** |
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* dma_resv_locking_ctx - returns the context used to lock the object |
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* @obj: the reservation object |
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* |
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* Returns the context used to lock a reservation object or NULL if no context |
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* was used or the object is not locked at all. |
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* |
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* WARNING: This interface is pretty horrible, but TTM needs it because it |
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* doesn't pass the struct ww_acquire_ctx around in some very long callchains. |
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* Everyone else just uses it to check whether they're holding a reservation or |
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* not. |
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*/ |
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static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj) |
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{ |
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return READ_ONCE(obj->lock.ctx); |
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} |
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/** |
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* dma_resv_unlock - unlock the reservation object |
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* @obj: the reservation object |
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* |
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* Unlocks the reservation object following exclusive access. |
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*/ |
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static inline void dma_resv_unlock(struct dma_resv *obj) |
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{ |
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dma_resv_reset_max_fences(obj); |
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ww_mutex_unlock(&obj->lock); |
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} |
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void dma_resv_init(struct dma_resv *obj); |
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void dma_resv_fini(struct dma_resv *obj); |
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int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences); |
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void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence, |
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enum dma_resv_usage usage); |
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void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context, |
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struct dma_fence *fence, |
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enum dma_resv_usage usage); |
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int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage, |
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unsigned int *num_fences, struct dma_fence ***fences); |
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int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage, |
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struct dma_fence **fence); |
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int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src); |
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long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage, |
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bool intr, unsigned long timeout); |
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bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage); |
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void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq); |
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#endif /* _LINUX_RESERVATION_H */
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