651 lines
16 KiB
C
651 lines
16 KiB
C
/*
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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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#include <linux/dma-resv.h>
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#include <linux/export.h>
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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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DEFINE_WD_CLASS(reservation_ww_class);
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EXPORT_SYMBOL(reservation_ww_class);
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struct lock_class_key reservation_seqcount_class;
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EXPORT_SYMBOL(reservation_seqcount_class);
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const char reservation_seqcount_string[] = "reservation_seqcount";
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EXPORT_SYMBOL(reservation_seqcount_string);
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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(offsetof(typeof(*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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/**
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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_init(&obj->seq, reservation_seqcount_string,
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&reservation_seqcount_class);
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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 = 4;
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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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preempt_disable();
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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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preempt_enable();
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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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preempt_disable();
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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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preempt_enable();
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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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preempt_disable();
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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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preempt_enable();
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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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if (!pfence_excl && fence_excl)
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sz += sizeof(*shared);
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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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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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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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* 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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if (dma_fence_is_signaled(fence)) {
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dma_fence_put(fence);
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fence = NULL;
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}
|
|
|
|
} else {
|
|
fence = NULL;
|
|
}
|
|
|
|
if (wait_all) {
|
|
struct dma_resv_list *fobj = rcu_dereference(obj->fence);
|
|
|
|
if (fobj)
|
|
shared_count = fobj->shared_count;
|
|
|
|
for (i = 0; !fence && i < shared_count; ++i) {
|
|
struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
|
|
|
|
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
|
|
&lfence->flags))
|
|
continue;
|
|
|
|
if (!dma_fence_get_rcu(lfence))
|
|
goto unlock_retry;
|
|
|
|
if (dma_fence_is_signaled(lfence)) {
|
|
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);
|