diff options
Diffstat (limited to 'drivers/dma-buf/dma-resv.c')
-rw-r--r-- | drivers/dma-buf/dma-resv.c | 603 |
1 files changed, 603 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c new file mode 100644 index 000000000000..f5142683c851 --- /dev/null +++ b/drivers/dma-buf/dma-resv.c @@ -0,0 +1,603 @@ +/* + * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst) + * + * Based on bo.c which bears the following copyright notice, + * but is dual licensed: + * + * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA + * All Rights Reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sub license, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice (including the + * next paragraph) shall be included in all copies or substantial portions + * of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE + * USE OR OTHER DEALINGS IN THE SOFTWARE. + * + **************************************************************************/ +/* + * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com> + */ + +#include <linux/dma-resv.h> +#include <linux/export.h> + +/** + * DOC: Reservation Object Overview + * + * The reservation object provides a mechanism to manage shared and + * exclusive fences associated with a buffer. A reservation object + * can have attached one exclusive fence (normally associated with + * write operations) or N shared fences (read operations). The RCU + * mechanism is used to protect read access to fences from locked + * write-side updates. + */ + +DEFINE_WD_CLASS(reservation_ww_class); +EXPORT_SYMBOL(reservation_ww_class); + +/** + * dma_resv_list_alloc - allocate fence list + * @shared_max: number of fences we need space for + * + * Allocate a new dma_resv_list and make sure to correctly initialize + * shared_max. + */ +static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max) +{ + struct dma_resv_list *list; + + list = kmalloc(offsetof(typeof(*list), shared[shared_max]), GFP_KERNEL); + if (!list) + return NULL; + + list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) / + sizeof(*list->shared); + + return list; +} + +/** + * dma_resv_list_free - free fence list + * @list: list to free + * + * Free a dma_resv_list and make sure to drop all references. + */ +static void dma_resv_list_free(struct dma_resv_list *list) +{ + unsigned int i; + + if (!list) + return; + + for (i = 0; i < list->shared_count; ++i) + dma_fence_put(rcu_dereference_protected(list->shared[i], true)); + + kfree_rcu(list, rcu); +} + +/** + * dma_resv_init - initialize a reservation object + * @obj: the reservation object + */ +void dma_resv_init(struct dma_resv *obj) +{ + ww_mutex_init(&obj->lock, &reservation_ww_class); + RCU_INIT_POINTER(obj->fence, NULL); + RCU_INIT_POINTER(obj->fence_excl, NULL); +} +EXPORT_SYMBOL(dma_resv_init); + +/** + * dma_resv_fini - destroys a reservation object + * @obj: the reservation object + */ +void dma_resv_fini(struct dma_resv *obj) +{ + struct dma_resv_list *fobj; + struct dma_fence *excl; + + /* + * This object should be dead and all references must have + * been released to it, so no need to be protected with rcu. + */ + excl = rcu_dereference_protected(obj->fence_excl, 1); + if (excl) + dma_fence_put(excl); + + fobj = rcu_dereference_protected(obj->fence, 1); + dma_resv_list_free(fobj); + ww_mutex_destroy(&obj->lock); +} +EXPORT_SYMBOL(dma_resv_fini); + +/** + * dma_resv_reserve_shared - Reserve space to add shared fences to + * a dma_resv. + * @obj: reservation object + * @num_fences: number of fences we want to add + * + * Should be called before dma_resv_add_shared_fence(). Must + * be called with obj->lock held. + * + * RETURNS + * Zero for success, or -errno + */ +int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences) +{ + struct dma_resv_list *old, *new; + unsigned int i, j, k, max; + + dma_resv_assert_held(obj); + + old = dma_resv_get_list(obj); + + if (old && old->shared_max) { + if ((old->shared_count + num_fences) <= old->shared_max) + return 0; + else + max = max(old->shared_count + num_fences, + old->shared_max * 2); + } else { + max = 4; + } + + new = dma_resv_list_alloc(max); + if (!new) + return -ENOMEM; + + /* + * no need to bump fence refcounts, rcu_read access + * requires the use of kref_get_unless_zero, and the + * references from the old struct are carried over to + * the new. + */ + for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) { + struct dma_fence *fence; + + fence = rcu_dereference_protected(old->shared[i], + dma_resv_held(obj)); + if (dma_fence_is_signaled(fence)) + RCU_INIT_POINTER(new->shared[--k], fence); + else + RCU_INIT_POINTER(new->shared[j++], fence); + } + new->shared_count = j; + + /* + * We are not changing the effective set of fences here so can + * merely update the pointer to the new array; both existing + * readers and new readers will see exactly the same set of + * active (unsignaled) shared fences. Individual fences and the + * old array are protected by RCU and so will not vanish under + * the gaze of the rcu_read_lock() readers. + */ + rcu_assign_pointer(obj->fence, new); + + if (!old) + return 0; + + /* Drop the references to the signaled fences */ + for (i = k; i < max; ++i) { + struct dma_fence *fence; + + fence = rcu_dereference_protected(new->shared[i], + dma_resv_held(obj)); + dma_fence_put(fence); + } + kfree_rcu(old, rcu); + + return 0; +} +EXPORT_SYMBOL(dma_resv_reserve_shared); + +/** + * dma_resv_add_shared_fence - Add a fence to a shared slot + * @obj: the reservation object + * @fence: the shared fence to add + * + * Add a fence to a shared slot, obj->lock must be held, and + * dma_resv_reserve_shared() has been called. + */ +void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence) +{ + struct dma_resv_list *fobj; + struct dma_fence *old; + unsigned int i, count; + + dma_fence_get(fence); + + dma_resv_assert_held(obj); + + fobj = dma_resv_get_list(obj); + count = fobj->shared_count; + + for (i = 0; i < count; ++i) { + + old = rcu_dereference_protected(fobj->shared[i], + dma_resv_held(obj)); + if (old->context == fence->context || + dma_fence_is_signaled(old)) + goto replace; + } + + BUG_ON(fobj->shared_count >= fobj->shared_max); + old = NULL; + count++; + +replace: + RCU_INIT_POINTER(fobj->shared[i], fence); + /* pointer update must be visible before we extend the shared_count */ + smp_store_mb(fobj->shared_count, count); + dma_fence_put(old); +} +EXPORT_SYMBOL(dma_resv_add_shared_fence); + +/** + * dma_resv_add_excl_fence - Add an exclusive fence. + * @obj: the reservation object + * @fence: the shared fence to add + * + * Add a fence to the exclusive slot. The obj->lock must be held. + */ +void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence) +{ + struct dma_fence *old_fence = dma_resv_get_excl(obj); + struct dma_resv_list *old; + u32 i = 0; + + dma_resv_assert_held(obj); + + old = dma_resv_get_list(obj); + if (old) + i = old->shared_count; + + if (fence) + dma_fence_get(fence); + + preempt_disable(); + rcu_assign_pointer(obj->fence_excl, fence); + /* pointer update must be visible before we modify the shared_count */ + if (old) + smp_store_mb(old->shared_count, 0); + preempt_enable(); + + /* inplace update, no shared fences */ + while (i--) + dma_fence_put(rcu_dereference_protected(old->shared[i], + dma_resv_held(obj))); + + dma_fence_put(old_fence); +} +EXPORT_SYMBOL(dma_resv_add_excl_fence); + +/** +* dma_resv_copy_fences - Copy all fences from src to dst. +* @dst: the destination reservation object +* @src: the source reservation object +* +* Copy all fences from src to dst. dst-lock must be held. +*/ +int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src) +{ + struct dma_resv_list *src_list, *dst_list; + struct dma_fence *old, *new; + unsigned int i, shared_count; + + dma_resv_assert_held(dst); + + rcu_read_lock(); + +retry: + dma_resv_fences(src, &new, &src_list, &shared_count); + if (shared_count) { + rcu_read_unlock(); + + dst_list = dma_resv_list_alloc(shared_count); + if (!dst_list) + return -ENOMEM; + + rcu_read_lock(); + dma_resv_fences(src, &new, &src_list, &shared_count); + if (!src_list || shared_count > dst_list->shared_max) { + kfree(dst_list); + goto retry; + } + + dst_list->shared_count = 0; + for (i = 0; i < shared_count; ++i) { + struct dma_fence *fence; + + fence = rcu_dereference(src_list->shared[i]); + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, + &fence->flags)) + continue; + + if (!dma_fence_get_rcu(fence)) { + dma_resv_list_free(dst_list); + goto retry; + } + + if (dma_fence_is_signaled(fence)) { + dma_fence_put(fence); + continue; + } + + rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence); + } + } else { + dst_list = NULL; + } + + if (new && !dma_fence_get_rcu(new)) { + dma_resv_list_free(dst_list); + goto retry; + } + rcu_read_unlock(); + + src_list = dma_resv_get_list(dst); + old = dma_resv_get_excl(dst); + + preempt_disable(); + rcu_assign_pointer(dst->fence_excl, new); + rcu_assign_pointer(dst->fence, dst_list); + preempt_enable(); + + dma_resv_list_free(src_list); + dma_fence_put(old); + + return 0; +} +EXPORT_SYMBOL(dma_resv_copy_fences); + +/** + * dma_resv_get_fences_rcu - Get an object's shared and exclusive + * fences without update side lock held + * @obj: the reservation object + * @pfence_excl: the returned exclusive fence (or NULL) + * @pshared_count: the number of shared fences returned + * @pshared: the array of shared fence ptrs returned (array is krealloc'd to + * the required size, and must be freed by caller) + * + * Retrieve all fences from the reservation object. If the pointer for the + * exclusive fence is not specified the fence is put into the array of the + * shared fences as well. Returns either zero or -ENOMEM. + */ +int dma_resv_get_fences_rcu(struct dma_resv *obj, + struct dma_fence **pfence_excl, + unsigned *pshared_count, + struct dma_fence ***pshared) +{ + struct dma_fence **shared = NULL; + struct dma_fence *fence_excl; + unsigned int shared_count; + int ret = 1; + + do { + struct dma_resv_list *fobj; + unsigned int i; + size_t sz = 0; + + i = 0; + + rcu_read_lock(); + dma_resv_fences(obj, &fence_excl, &fobj, + &shared_count); + + if (fence_excl && !dma_fence_get_rcu(fence_excl)) + goto unlock; + + if (fobj) + sz += sizeof(*shared) * fobj->shared_max; + + if (!pfence_excl && fence_excl) + sz += sizeof(*shared); + + if (sz) { + struct dma_fence **nshared; + + nshared = krealloc(shared, sz, + GFP_NOWAIT | __GFP_NOWARN); + if (!nshared) { + rcu_read_unlock(); + + dma_fence_put(fence_excl); + fence_excl = NULL; + + nshared = krealloc(shared, sz, GFP_KERNEL); + if (nshared) { + shared = nshared; + continue; + } + + ret = -ENOMEM; + break; + } + shared = nshared; + for (i = 0; i < shared_count; ++i) { + shared[i] = rcu_dereference(fobj->shared[i]); + if (!dma_fence_get_rcu(shared[i])) + break; + } + } + + if (i != shared_count) { + while (i--) + dma_fence_put(shared[i]); + dma_fence_put(fence_excl); + goto unlock; + } + + ret = 0; +unlock: + rcu_read_unlock(); + } while (ret); + + if (pfence_excl) + *pfence_excl = fence_excl; + else if (fence_excl) + shared[++shared_count] = fence_excl; + + if (!shared_count) { + kfree(shared); + shared = NULL; + } + + *pshared_count = shared_count; + *pshared = shared; + return ret; +} +EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu); + +/** + * dma_resv_wait_timeout_rcu - Wait on reservation's objects + * shared and/or exclusive fences. + * @obj: the reservation object + * @wait_all: if true, wait on all fences, else wait on just exclusive fence + * @intr: if true, do interruptible wait + * @timeout: timeout value in jiffies or zero to return immediately + * + * RETURNS + * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or + * greater than zer on success. + */ +long dma_resv_wait_timeout_rcu(struct dma_resv *obj, + bool wait_all, bool intr, + unsigned long timeout) +{ + struct dma_resv_list *fobj; + struct dma_fence *fence; + unsigned shared_count; + long ret = timeout ? timeout : 1; + int i; + +retry: + rcu_read_lock(); + i = -1; + + dma_resv_fences(obj, &fence, &fobj, &shared_count); + if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + if (!dma_fence_get_rcu(fence)) + goto unlock_retry; + + if (dma_fence_is_signaled(fence)) { + dma_fence_put(fence); + fence = NULL; + } + + } else { + fence = NULL; + } + + if (wait_all) { + 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) { + 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) +{ + struct dma_resv_list *fobj; + struct dma_fence *fence_excl; + unsigned shared_count; + int ret; + + rcu_read_lock(); +retry: + ret = true; + + dma_resv_fences(obj, &fence_excl, &fobj, &shared_count); + if (test_all) { + unsigned i; + + 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 (!shared_count && fence_excl) { + ret = dma_resv_test_signaled_single(fence_excl); + if (ret < 0) + goto retry; + } + + rcu_read_unlock(); + return ret; +} +EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu); |