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683 lines
16 KiB
683 lines
16 KiB
/* |
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* Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst) |
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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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**************************************************************************/ |
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/* |
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* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com> |
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*/ |
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|
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#include <linux/dma-resv.h> |
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#include <linux/export.h> |
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#include <linux/mm.h> |
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#include <linux/sched/mm.h> |
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#include <linux/mmu_notifier.h> |
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|
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/** |
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* DOC: Reservation Object Overview |
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* |
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* The reservation object provides a mechanism to manage shared and |
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* exclusive fences associated with a buffer. A reservation object |
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* can have attached one exclusive fence (normally associated with |
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* write operations) or N shared fences (read operations). The RCU |
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* mechanism is used to protect read access to fences from locked |
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* write-side updates. |
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*/ |
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|
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DEFINE_WD_CLASS(reservation_ww_class); |
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EXPORT_SYMBOL(reservation_ww_class); |
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|
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/** |
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* dma_resv_list_alloc - allocate fence list |
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* @shared_max: number of fences we need space for |
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* |
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* Allocate a new dma_resv_list and make sure to correctly initialize |
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* shared_max. |
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*/ |
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static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max) |
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{ |
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struct dma_resv_list *list; |
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list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL); |
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if (!list) |
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return NULL; |
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list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) / |
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sizeof(*list->shared); |
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return list; |
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} |
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/** |
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* dma_resv_list_free - free fence list |
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* @list: list to free |
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* |
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* Free a dma_resv_list and make sure to drop all references. |
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*/ |
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static void dma_resv_list_free(struct dma_resv_list *list) |
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{ |
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unsigned int i; |
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if (!list) |
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return; |
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for (i = 0; i < list->shared_count; ++i) |
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dma_fence_put(rcu_dereference_protected(list->shared[i], true)); |
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kfree_rcu(list, rcu); |
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} |
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#if IS_ENABLED(CONFIG_LOCKDEP) |
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static int __init dma_resv_lockdep(void) |
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{ |
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struct mm_struct *mm = mm_alloc(); |
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struct ww_acquire_ctx ctx; |
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struct dma_resv obj; |
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struct address_space mapping; |
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int ret; |
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if (!mm) |
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return -ENOMEM; |
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dma_resv_init(&obj); |
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address_space_init_once(&mapping); |
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mmap_read_lock(mm); |
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ww_acquire_init(&ctx, &reservation_ww_class); |
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ret = dma_resv_lock(&obj, &ctx); |
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if (ret == -EDEADLK) |
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dma_resv_lock_slow(&obj, &ctx); |
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fs_reclaim_acquire(GFP_KERNEL); |
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/* for unmap_mapping_range on trylocked buffer objects in shrinkers */ |
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i_mmap_lock_write(&mapping); |
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i_mmap_unlock_write(&mapping); |
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#ifdef CONFIG_MMU_NOTIFIER |
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lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); |
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__dma_fence_might_wait(); |
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lock_map_release(&__mmu_notifier_invalidate_range_start_map); |
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#else |
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__dma_fence_might_wait(); |
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#endif |
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fs_reclaim_release(GFP_KERNEL); |
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ww_mutex_unlock(&obj.lock); |
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ww_acquire_fini(&ctx); |
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mmap_read_unlock(mm); |
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mmput(mm); |
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return 0; |
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} |
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subsys_initcall(dma_resv_lockdep); |
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#endif |
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/** |
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* dma_resv_init - initialize a reservation object |
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* @obj: the reservation object |
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*/ |
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void dma_resv_init(struct dma_resv *obj) |
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{ |
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ww_mutex_init(&obj->lock, &reservation_ww_class); |
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seqcount_ww_mutex_init(&obj->seq, &obj->lock); |
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RCU_INIT_POINTER(obj->fence, NULL); |
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RCU_INIT_POINTER(obj->fence_excl, NULL); |
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} |
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EXPORT_SYMBOL(dma_resv_init); |
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/** |
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* dma_resv_fini - destroys a reservation object |
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* @obj: the reservation object |
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*/ |
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void dma_resv_fini(struct dma_resv *obj) |
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{ |
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struct dma_resv_list *fobj; |
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struct dma_fence *excl; |
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/* |
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* This object should be dead and all references must have |
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* been released to it, so no need to be protected with rcu. |
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*/ |
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excl = rcu_dereference_protected(obj->fence_excl, 1); |
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if (excl) |
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dma_fence_put(excl); |
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fobj = rcu_dereference_protected(obj->fence, 1); |
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dma_resv_list_free(fobj); |
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ww_mutex_destroy(&obj->lock); |
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} |
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EXPORT_SYMBOL(dma_resv_fini); |
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/** |
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* dma_resv_reserve_shared - Reserve space to add shared fences to |
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* a dma_resv. |
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* @obj: reservation object |
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* @num_fences: number of fences we want to add |
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* |
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* Should be called before dma_resv_add_shared_fence(). Must |
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* be called with obj->lock held. |
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* |
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* RETURNS |
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* Zero for success, or -errno |
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*/ |
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int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences) |
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{ |
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struct dma_resv_list *old, *new; |
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unsigned int i, j, k, max; |
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dma_resv_assert_held(obj); |
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old = dma_resv_get_list(obj); |
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if (old && old->shared_max) { |
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if ((old->shared_count + num_fences) <= old->shared_max) |
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return 0; |
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else |
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max = max(old->shared_count + num_fences, |
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old->shared_max * 2); |
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} else { |
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max = max(4ul, roundup_pow_of_two(num_fences)); |
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} |
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new = dma_resv_list_alloc(max); |
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if (!new) |
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return -ENOMEM; |
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/* |
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* no need to bump fence refcounts, rcu_read access |
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* requires the use of kref_get_unless_zero, and the |
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* references from the old struct are carried over to |
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* the new. |
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*/ |
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for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) { |
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struct dma_fence *fence; |
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fence = rcu_dereference_protected(old->shared[i], |
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dma_resv_held(obj)); |
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if (dma_fence_is_signaled(fence)) |
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RCU_INIT_POINTER(new->shared[--k], fence); |
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else |
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RCU_INIT_POINTER(new->shared[j++], fence); |
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} |
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new->shared_count = j; |
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/* |
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* We are not changing the effective set of fences here so can |
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* merely update the pointer to the new array; both existing |
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* readers and new readers will see exactly the same set of |
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* active (unsignaled) shared fences. Individual fences and the |
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* old array are protected by RCU and so will not vanish under |
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* the gaze of the rcu_read_lock() readers. |
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*/ |
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rcu_assign_pointer(obj->fence, new); |
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if (!old) |
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return 0; |
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/* Drop the references to the signaled fences */ |
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for (i = k; i < max; ++i) { |
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struct dma_fence *fence; |
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fence = rcu_dereference_protected(new->shared[i], |
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dma_resv_held(obj)); |
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dma_fence_put(fence); |
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} |
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kfree_rcu(old, rcu); |
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return 0; |
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} |
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EXPORT_SYMBOL(dma_resv_reserve_shared); |
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/** |
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* dma_resv_add_shared_fence - Add a fence to a shared slot |
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* @obj: the reservation object |
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* @fence: the shared fence to add |
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* |
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* Add a fence to a shared slot, obj->lock must be held, and |
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* dma_resv_reserve_shared() has been called. |
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*/ |
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void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence) |
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{ |
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struct dma_resv_list *fobj; |
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struct dma_fence *old; |
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unsigned int i, count; |
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dma_fence_get(fence); |
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dma_resv_assert_held(obj); |
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fobj = dma_resv_get_list(obj); |
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count = fobj->shared_count; |
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write_seqcount_begin(&obj->seq); |
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for (i = 0; i < count; ++i) { |
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old = rcu_dereference_protected(fobj->shared[i], |
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dma_resv_held(obj)); |
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if (old->context == fence->context || |
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dma_fence_is_signaled(old)) |
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goto replace; |
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} |
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BUG_ON(fobj->shared_count >= fobj->shared_max); |
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old = NULL; |
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count++; |
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replace: |
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RCU_INIT_POINTER(fobj->shared[i], fence); |
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/* pointer update must be visible before we extend the shared_count */ |
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smp_store_mb(fobj->shared_count, count); |
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write_seqcount_end(&obj->seq); |
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dma_fence_put(old); |
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} |
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EXPORT_SYMBOL(dma_resv_add_shared_fence); |
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/** |
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* dma_resv_add_excl_fence - Add an exclusive fence. |
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* @obj: the reservation object |
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* @fence: the shared fence to add |
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* |
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* Add a fence to the exclusive slot. The obj->lock must be held. |
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*/ |
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void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence) |
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{ |
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struct dma_fence *old_fence = dma_resv_get_excl(obj); |
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struct dma_resv_list *old; |
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u32 i = 0; |
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dma_resv_assert_held(obj); |
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old = dma_resv_get_list(obj); |
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if (old) |
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i = old->shared_count; |
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if (fence) |
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dma_fence_get(fence); |
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write_seqcount_begin(&obj->seq); |
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/* write_seqcount_begin provides the necessary memory barrier */ |
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RCU_INIT_POINTER(obj->fence_excl, fence); |
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if (old) |
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old->shared_count = 0; |
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write_seqcount_end(&obj->seq); |
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/* inplace update, no shared fences */ |
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while (i--) |
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dma_fence_put(rcu_dereference_protected(old->shared[i], |
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dma_resv_held(obj))); |
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dma_fence_put(old_fence); |
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} |
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EXPORT_SYMBOL(dma_resv_add_excl_fence); |
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/** |
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* dma_resv_copy_fences - Copy all fences from src to dst. |
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* @dst: the destination reservation object |
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* @src: the source reservation object |
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* |
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* Copy all fences from src to dst. dst-lock must be held. |
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*/ |
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int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src) |
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{ |
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struct dma_resv_list *src_list, *dst_list; |
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struct dma_fence *old, *new; |
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unsigned i; |
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dma_resv_assert_held(dst); |
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rcu_read_lock(); |
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src_list = rcu_dereference(src->fence); |
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retry: |
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if (src_list) { |
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unsigned shared_count = src_list->shared_count; |
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rcu_read_unlock(); |
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dst_list = dma_resv_list_alloc(shared_count); |
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if (!dst_list) |
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return -ENOMEM; |
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rcu_read_lock(); |
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src_list = rcu_dereference(src->fence); |
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if (!src_list || src_list->shared_count > shared_count) { |
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kfree(dst_list); |
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goto retry; |
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} |
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dst_list->shared_count = 0; |
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for (i = 0; i < src_list->shared_count; ++i) { |
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struct dma_fence *fence; |
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fence = rcu_dereference(src_list->shared[i]); |
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if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, |
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&fence->flags)) |
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continue; |
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if (!dma_fence_get_rcu(fence)) { |
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dma_resv_list_free(dst_list); |
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src_list = rcu_dereference(src->fence); |
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goto retry; |
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} |
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if (dma_fence_is_signaled(fence)) { |
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dma_fence_put(fence); |
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continue; |
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} |
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rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence); |
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} |
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} else { |
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dst_list = NULL; |
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} |
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new = dma_fence_get_rcu_safe(&src->fence_excl); |
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rcu_read_unlock(); |
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src_list = dma_resv_get_list(dst); |
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old = dma_resv_get_excl(dst); |
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write_seqcount_begin(&dst->seq); |
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/* write_seqcount_begin provides the necessary memory barrier */ |
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RCU_INIT_POINTER(dst->fence_excl, new); |
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RCU_INIT_POINTER(dst->fence, dst_list); |
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write_seqcount_end(&dst->seq); |
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dma_resv_list_free(src_list); |
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dma_fence_put(old); |
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return 0; |
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} |
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EXPORT_SYMBOL(dma_resv_copy_fences); |
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/** |
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* dma_resv_get_fences_rcu - Get an object's shared and exclusive |
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* fences without update side lock held |
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* @obj: the reservation object |
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* @pfence_excl: the returned exclusive fence (or NULL) |
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* @pshared_count: the number of shared fences returned |
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* @pshared: the array of shared fence ptrs returned (array is krealloc'd to |
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* the required size, and must be freed by caller) |
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* |
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* Retrieve all fences from the reservation object. If the pointer for the |
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* exclusive fence is not specified the fence is put into the array of the |
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* shared fences as well. Returns either zero or -ENOMEM. |
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*/ |
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int dma_resv_get_fences_rcu(struct dma_resv *obj, |
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struct dma_fence **pfence_excl, |
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unsigned *pshared_count, |
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struct dma_fence ***pshared) |
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{ |
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struct dma_fence **shared = NULL; |
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struct dma_fence *fence_excl; |
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unsigned int shared_count; |
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int ret = 1; |
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do { |
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struct dma_resv_list *fobj; |
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unsigned int i, seq; |
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size_t sz = 0; |
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shared_count = i = 0; |
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rcu_read_lock(); |
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seq = read_seqcount_begin(&obj->seq); |
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fence_excl = rcu_dereference(obj->fence_excl); |
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if (fence_excl && !dma_fence_get_rcu(fence_excl)) |
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goto unlock; |
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fobj = rcu_dereference(obj->fence); |
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if (fobj) |
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sz += sizeof(*shared) * fobj->shared_max; |
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|
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if (!pfence_excl && fence_excl) |
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sz += sizeof(*shared); |
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|
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if (sz) { |
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struct dma_fence **nshared; |
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nshared = krealloc(shared, sz, |
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GFP_NOWAIT | __GFP_NOWARN); |
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if (!nshared) { |
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rcu_read_unlock(); |
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dma_fence_put(fence_excl); |
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fence_excl = NULL; |
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nshared = krealloc(shared, sz, GFP_KERNEL); |
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if (nshared) { |
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shared = nshared; |
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continue; |
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} |
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ret = -ENOMEM; |
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break; |
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} |
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shared = nshared; |
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shared_count = fobj ? fobj->shared_count : 0; |
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for (i = 0; i < shared_count; ++i) { |
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shared[i] = rcu_dereference(fobj->shared[i]); |
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if (!dma_fence_get_rcu(shared[i])) |
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break; |
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} |
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} |
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|
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if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) { |
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while (i--) |
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dma_fence_put(shared[i]); |
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dma_fence_put(fence_excl); |
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goto unlock; |
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} |
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ret = 0; |
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unlock: |
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rcu_read_unlock(); |
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} while (ret); |
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if (pfence_excl) |
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*pfence_excl = fence_excl; |
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else if (fence_excl) |
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shared[shared_count++] = fence_excl; |
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|
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if (!shared_count) { |
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kfree(shared); |
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shared = NULL; |
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} |
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*pshared_count = shared_count; |
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*pshared = shared; |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu); |
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|
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/** |
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* dma_resv_wait_timeout_rcu - Wait on reservation's objects |
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* shared and/or exclusive fences. |
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* @obj: the reservation object |
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* @wait_all: if true, wait on all fences, else wait on just exclusive fence |
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* @intr: if true, do interruptible wait |
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* @timeout: timeout value in jiffies or zero to return immediately |
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* |
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* RETURNS |
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* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or |
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* greater than zer on success. |
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*/ |
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long dma_resv_wait_timeout_rcu(struct dma_resv *obj, |
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bool wait_all, bool intr, |
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unsigned long timeout) |
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{ |
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struct dma_fence *fence; |
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unsigned seq, shared_count; |
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long ret = timeout ? timeout : 1; |
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int i; |
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retry: |
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shared_count = 0; |
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seq = read_seqcount_begin(&obj->seq); |
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rcu_read_lock(); |
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i = -1; |
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fence = rcu_dereference(obj->fence_excl); |
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if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { |
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if (!dma_fence_get_rcu(fence)) |
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goto unlock_retry; |
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|
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if (dma_fence_is_signaled(fence)) { |
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dma_fence_put(fence); |
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fence = NULL; |
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} |
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|
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} else { |
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fence = NULL; |
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} |
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if (wait_all) { |
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struct dma_resv_list *fobj = rcu_dereference(obj->fence); |
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|
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if (fobj) |
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shared_count = fobj->shared_count; |
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|
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for (i = 0; !fence && i < shared_count; ++i) { |
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struct dma_fence *lfence = rcu_dereference(fobj->shared[i]); |
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|
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if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, |
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&lfence->flags)) |
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continue; |
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|
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if (!dma_fence_get_rcu(lfence)) |
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goto unlock_retry; |
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|
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if (dma_fence_is_signaled(lfence)) { |
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dma_fence_put(lfence); |
|
continue; |
|
} |
|
|
|
fence = lfence; |
|
break; |
|
} |
|
} |
|
|
|
rcu_read_unlock(); |
|
if (fence) { |
|
if (read_seqcount_retry(&obj->seq, seq)) { |
|
dma_fence_put(fence); |
|
goto retry; |
|
} |
|
|
|
ret = dma_fence_wait_timeout(fence, intr, ret); |
|
dma_fence_put(fence); |
|
if (ret > 0 && wait_all && (i + 1 < shared_count)) |
|
goto retry; |
|
} |
|
return ret; |
|
|
|
unlock_retry: |
|
rcu_read_unlock(); |
|
goto retry; |
|
} |
|
EXPORT_SYMBOL_GPL(dma_resv_wait_timeout_rcu); |
|
|
|
|
|
static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence) |
|
{ |
|
struct dma_fence *fence, *lfence = passed_fence; |
|
int ret = 1; |
|
|
|
if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) { |
|
fence = dma_fence_get_rcu(lfence); |
|
if (!fence) |
|
return -1; |
|
|
|
ret = !!dma_fence_is_signaled(fence); |
|
dma_fence_put(fence); |
|
} |
|
return ret; |
|
} |
|
|
|
/** |
|
* dma_resv_test_signaled_rcu - Test if a reservation object's |
|
* fences have been signaled. |
|
* @obj: the reservation object |
|
* @test_all: if true, test all fences, otherwise only test the exclusive |
|
* fence |
|
* |
|
* RETURNS |
|
* true if all fences signaled, else false |
|
*/ |
|
bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all) |
|
{ |
|
unsigned seq, shared_count; |
|
int ret; |
|
|
|
rcu_read_lock(); |
|
retry: |
|
ret = true; |
|
shared_count = 0; |
|
seq = read_seqcount_begin(&obj->seq); |
|
|
|
if (test_all) { |
|
unsigned i; |
|
|
|
struct dma_resv_list *fobj = rcu_dereference(obj->fence); |
|
|
|
if (fobj) |
|
shared_count = fobj->shared_count; |
|
|
|
for (i = 0; i < shared_count; ++i) { |
|
struct dma_fence *fence = rcu_dereference(fobj->shared[i]); |
|
|
|
ret = dma_resv_test_signaled_single(fence); |
|
if (ret < 0) |
|
goto retry; |
|
else if (!ret) |
|
break; |
|
} |
|
|
|
if (read_seqcount_retry(&obj->seq, seq)) |
|
goto retry; |
|
} |
|
|
|
if (!shared_count) { |
|
struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl); |
|
|
|
if (fence_excl) { |
|
ret = dma_resv_test_signaled_single(fence_excl); |
|
if (ret < 0) |
|
goto retry; |
|
|
|
if (read_seqcount_retry(&obj->seq, seq)) |
|
goto retry; |
|
} |
|
} |
|
|
|
rcu_read_unlock(); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu);
|
|
|