diff options
Diffstat (limited to 'drivers/dma-buf/dma-resv.c')
| -rw-r--r-- | drivers/dma-buf/dma-resv.c | 779 |
1 files changed, 779 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c new file mode 100644 index 000000000..e78ff9333 --- /dev/null +++ b/drivers/dma-buf/dma-resv.c @@ -0,0 +1,779 @@ +// SPDX-License-Identifier: MIT +/* + * 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/dma-fence-array.h> +#include <linux/export.h> +#include <linux/mm.h> +#include <linux/sched/mm.h> +#include <linux/mmu_notifier.h> +#include <linux/seq_file.h> + +/** + * DOC: Reservation Object Overview + * + * The reservation object provides a mechanism to manage a container of + * dma_fence object associated with a resource. A reservation object + * can have any number of fences attaches to it. Each fence carries an usage + * parameter determining how the operation represented by the fence is using the + * resource. The RCU mechanism is used to protect read access to fences from + * locked write-side updates. + * + * See struct dma_resv for more details. + */ + +DEFINE_WD_CLASS(reservation_ww_class); +EXPORT_SYMBOL(reservation_ww_class); + +/* Mask for the lower fence pointer bits */ +#define DMA_RESV_LIST_MASK 0x3 + +struct dma_resv_list { + struct rcu_head rcu; + u32 num_fences, max_fences; + struct dma_fence __rcu *table[]; +}; + +/* Extract the fence and usage flags from an RCU protected entry in the list. */ +static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index, + struct dma_resv *resv, struct dma_fence **fence, + enum dma_resv_usage *usage) +{ + long tmp; + + tmp = (long)rcu_dereference_check(list->table[index], + resv ? dma_resv_held(resv) : true); + *fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK); + if (usage) + *usage = tmp & DMA_RESV_LIST_MASK; +} + +/* Set the fence and usage flags at the specific index in the list. */ +static void dma_resv_list_set(struct dma_resv_list *list, + unsigned int index, + struct dma_fence *fence, + enum dma_resv_usage usage) +{ + long tmp = ((long)fence) | usage; + + RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp); +} + +/* + * Allocate a new dma_resv_list and make sure to correctly initialize + * max_fences. + */ +static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences) +{ + struct dma_resv_list *list; + + list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL); + if (!list) + return NULL; + + list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) / + sizeof(*list->table); + + return list; +} + +/* 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->num_fences; ++i) { + struct dma_fence *fence; + + dma_resv_list_entry(list, i, NULL, &fence, NULL); + dma_fence_put(fence); + } + 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->fences, 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) +{ + /* + * This object should be dead and all references must have + * been released to it, so no need to be protected with rcu. + */ + dma_resv_list_free(rcu_dereference_protected(obj->fences, true)); + ww_mutex_destroy(&obj->lock); +} +EXPORT_SYMBOL(dma_resv_fini); + +/* Dereference the fences while ensuring RCU rules */ +static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj) +{ + return rcu_dereference_check(obj->fences, dma_resv_held(obj)); +} + +/** + * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object. + * @obj: reservation object + * @num_fences: number of fences we want to add + * + * Should be called before dma_resv_add_fence(). Must be called with @obj + * locked through dma_resv_lock(). + * + * Note that the preallocated slots need to be re-reserved if @obj is unlocked + * at any time before calling dma_resv_add_fence(). This is validated when + * CONFIG_DEBUG_MUTEXES is enabled. + * + * RETURNS + * Zero for success, or -errno + */ +int dma_resv_reserve_fences(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_fences_list(obj); + if (old && old->max_fences) { + if ((old->num_fences + num_fences) <= old->max_fences) + return 0; + max = max(old->num_fences + num_fences, old->max_fences * 2); + } else { + max = max(4ul, roundup_pow_of_two(num_fences)); + } + + 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->num_fences : 0); ++i) { + enum dma_resv_usage usage; + struct dma_fence *fence; + + dma_resv_list_entry(old, i, obj, &fence, &usage); + if (dma_fence_is_signaled(fence)) + RCU_INIT_POINTER(new->table[--k], fence); + else + dma_resv_list_set(new, j++, fence, usage); + } + new->num_fences = 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) 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->fences, 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->table[i], + dma_resv_held(obj)); + dma_fence_put(fence); + } + kfree_rcu(old, rcu); + + return 0; +} +EXPORT_SYMBOL(dma_resv_reserve_fences); + +#ifdef CONFIG_DEBUG_MUTEXES +/** + * dma_resv_reset_max_fences - reset fences for debugging + * @obj: the dma_resv object to reset + * + * Reset the number of pre-reserved fence slots to test that drivers do + * correct slot allocation using dma_resv_reserve_fences(). See also + * &dma_resv_list.max_fences. + */ +void dma_resv_reset_max_fences(struct dma_resv *obj) +{ + struct dma_resv_list *fences = dma_resv_fences_list(obj); + + dma_resv_assert_held(obj); + + /* Test fence slot reservation */ + if (fences) + fences->max_fences = fences->num_fences; +} +EXPORT_SYMBOL(dma_resv_reset_max_fences); +#endif + +/** + * dma_resv_add_fence - Add a fence to the dma_resv obj + * @obj: the reservation object + * @fence: the fence to add + * @usage: how the fence is used, see enum dma_resv_usage + * + * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and + * dma_resv_reserve_fences() has been called. + * + * See also &dma_resv.fence for a discussion of the semantics. + */ +void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence, + enum dma_resv_usage usage) +{ + struct dma_resv_list *fobj; + struct dma_fence *old; + unsigned int i, count; + + dma_fence_get(fence); + + dma_resv_assert_held(obj); + + /* Drivers should not add containers here, instead add each fence + * individually. + */ + WARN_ON(dma_fence_is_container(fence)); + + fobj = dma_resv_fences_list(obj); + count = fobj->num_fences; + + for (i = 0; i < count; ++i) { + enum dma_resv_usage old_usage; + + dma_resv_list_entry(fobj, i, obj, &old, &old_usage); + if ((old->context == fence->context && old_usage >= usage && + dma_fence_is_later_or_same(fence, old)) || + dma_fence_is_signaled(old)) { + dma_resv_list_set(fobj, i, fence, usage); + dma_fence_put(old); + return; + } + } + + BUG_ON(fobj->num_fences >= fobj->max_fences); + count++; + + dma_resv_list_set(fobj, i, fence, usage); + /* pointer update must be visible before we extend the num_fences */ + smp_store_mb(fobj->num_fences, count); +} +EXPORT_SYMBOL(dma_resv_add_fence); + +/** + * dma_resv_replace_fences - replace fences in the dma_resv obj + * @obj: the reservation object + * @context: the context of the fences to replace + * @replacement: the new fence to use instead + * @usage: how the new fence is used, see enum dma_resv_usage + * + * Replace fences with a specified context with a new fence. Only valid if the + * operation represented by the original fence has no longer access to the + * resources represented by the dma_resv object when the new fence completes. + * + * And example for using this is replacing a preemption fence with a page table + * update fence which makes the resource inaccessible. + */ +void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context, + struct dma_fence *replacement, + enum dma_resv_usage usage) +{ + struct dma_resv_list *list; + unsigned int i; + + dma_resv_assert_held(obj); + + list = dma_resv_fences_list(obj); + for (i = 0; list && i < list->num_fences; ++i) { + struct dma_fence *old; + + dma_resv_list_entry(list, i, obj, &old, NULL); + if (old->context != context) + continue; + + dma_resv_list_set(list, i, dma_fence_get(replacement), usage); + dma_fence_put(old); + } +} +EXPORT_SYMBOL(dma_resv_replace_fences); + +/* Restart the unlocked iteration by initializing the cursor object. */ +static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor) +{ + cursor->index = 0; + cursor->num_fences = 0; + cursor->fences = dma_resv_fences_list(cursor->obj); + if (cursor->fences) + cursor->num_fences = cursor->fences->num_fences; + cursor->is_restarted = true; +} + +/* Walk to the next not signaled fence and grab a reference to it */ +static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor) +{ + if (!cursor->fences) + return; + + do { + /* Drop the reference from the previous round */ + dma_fence_put(cursor->fence); + + if (cursor->index >= cursor->num_fences) { + cursor->fence = NULL; + break; + + } + + dma_resv_list_entry(cursor->fences, cursor->index++, + cursor->obj, &cursor->fence, + &cursor->fence_usage); + cursor->fence = dma_fence_get_rcu(cursor->fence); + if (!cursor->fence) { + dma_resv_iter_restart_unlocked(cursor); + continue; + } + + if (!dma_fence_is_signaled(cursor->fence) && + cursor->usage >= cursor->fence_usage) + break; + } while (true); +} + +/** + * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj. + * @cursor: the cursor with the current position + * + * Subsequent fences are iterated with dma_resv_iter_next_unlocked(). + * + * Beware that the iterator can be restarted. Code which accumulates statistics + * or similar needs to check for this with dma_resv_iter_is_restarted(). For + * this reason prefer the locked dma_resv_iter_first() whenver possible. + * + * Returns the first fence from an unlocked dma_resv obj. + */ +struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor) +{ + rcu_read_lock(); + do { + dma_resv_iter_restart_unlocked(cursor); + dma_resv_iter_walk_unlocked(cursor); + } while (dma_resv_fences_list(cursor->obj) != cursor->fences); + rcu_read_unlock(); + + return cursor->fence; +} +EXPORT_SYMBOL(dma_resv_iter_first_unlocked); + +/** + * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj. + * @cursor: the cursor with the current position + * + * Beware that the iterator can be restarted. Code which accumulates statistics + * or similar needs to check for this with dma_resv_iter_is_restarted(). For + * this reason prefer the locked dma_resv_iter_next() whenver possible. + * + * Returns the next fence from an unlocked dma_resv obj. + */ +struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor) +{ + bool restart; + + rcu_read_lock(); + cursor->is_restarted = false; + restart = dma_resv_fences_list(cursor->obj) != cursor->fences; + do { + if (restart) + dma_resv_iter_restart_unlocked(cursor); + dma_resv_iter_walk_unlocked(cursor); + restart = true; + } while (dma_resv_fences_list(cursor->obj) != cursor->fences); + rcu_read_unlock(); + + return cursor->fence; +} +EXPORT_SYMBOL(dma_resv_iter_next_unlocked); + +/** + * dma_resv_iter_first - first fence from a locked dma_resv object + * @cursor: cursor to record the current position + * + * Subsequent fences are iterated with dma_resv_iter_next_unlocked(). + * + * Return the first fence in the dma_resv object while holding the + * &dma_resv.lock. + */ +struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor) +{ + struct dma_fence *fence; + + dma_resv_assert_held(cursor->obj); + + cursor->index = 0; + cursor->fences = dma_resv_fences_list(cursor->obj); + + fence = dma_resv_iter_next(cursor); + cursor->is_restarted = true; + return fence; +} +EXPORT_SYMBOL_GPL(dma_resv_iter_first); + +/** + * dma_resv_iter_next - next fence from a locked dma_resv object + * @cursor: cursor to record the current position + * + * Return the next fences from the dma_resv object while holding the + * &dma_resv.lock. + */ +struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor) +{ + struct dma_fence *fence; + + dma_resv_assert_held(cursor->obj); + + cursor->is_restarted = false; + + do { + if (!cursor->fences || + cursor->index >= cursor->fences->num_fences) + return NULL; + + dma_resv_list_entry(cursor->fences, cursor->index++, + cursor->obj, &fence, &cursor->fence_usage); + } while (cursor->fence_usage > cursor->usage); + + return fence; +} +EXPORT_SYMBOL_GPL(dma_resv_iter_next); + +/** + * 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_iter cursor; + struct dma_resv_list *list; + struct dma_fence *f; + + dma_resv_assert_held(dst); + + list = NULL; + + dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP); + dma_resv_for_each_fence_unlocked(&cursor, f) { + + if (dma_resv_iter_is_restarted(&cursor)) { + dma_resv_list_free(list); + + list = dma_resv_list_alloc(cursor.num_fences); + if (!list) { + dma_resv_iter_end(&cursor); + return -ENOMEM; + } + list->num_fences = 0; + } + + dma_fence_get(f); + dma_resv_list_set(list, list->num_fences++, f, + dma_resv_iter_usage(&cursor)); + } + dma_resv_iter_end(&cursor); + + list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst)); + dma_resv_list_free(list); + return 0; +} +EXPORT_SYMBOL(dma_resv_copy_fences); + +/** + * dma_resv_get_fences - Get an object's fences + * fences without update side lock held + * @obj: the reservation object + * @usage: controls which fences to include, see enum dma_resv_usage. + * @num_fences: the number of fences returned + * @fences: the array of fence ptrs returned (array is krealloc'd to the + * required size, and must be freed by caller) + * + * Retrieve all fences from the reservation object. + * Returns either zero or -ENOMEM. + */ +int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage, + unsigned int *num_fences, struct dma_fence ***fences) +{ + struct dma_resv_iter cursor; + struct dma_fence *fence; + + *num_fences = 0; + *fences = NULL; + + dma_resv_iter_begin(&cursor, obj, usage); + dma_resv_for_each_fence_unlocked(&cursor, fence) { + + if (dma_resv_iter_is_restarted(&cursor)) { + struct dma_fence **new_fences; + unsigned int count; + + while (*num_fences) + dma_fence_put((*fences)[--(*num_fences)]); + + count = cursor.num_fences + 1; + + /* Eventually re-allocate the array */ + new_fences = krealloc_array(*fences, count, + sizeof(void *), + GFP_KERNEL); + if (count && !new_fences) { + kfree(*fences); + *fences = NULL; + *num_fences = 0; + dma_resv_iter_end(&cursor); + return -ENOMEM; + } + *fences = new_fences; + } + + (*fences)[(*num_fences)++] = dma_fence_get(fence); + } + dma_resv_iter_end(&cursor); + + return 0; +} +EXPORT_SYMBOL_GPL(dma_resv_get_fences); + +/** + * dma_resv_get_singleton - Get a single fence for all the fences + * @obj: the reservation object + * @usage: controls which fences to include, see enum dma_resv_usage. + * @fence: the resulting fence + * + * Get a single fence representing all the fences inside the resv object. + * Returns either 0 for success or -ENOMEM. + * + * Warning: This can't be used like this when adding the fence back to the resv + * object since that can lead to stack corruption when finalizing the + * dma_fence_array. + * + * Returns 0 on success and negative error values on failure. + */ +int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage, + struct dma_fence **fence) +{ + struct dma_fence_array *array; + struct dma_fence **fences; + unsigned count; + int r; + + r = dma_resv_get_fences(obj, usage, &count, &fences); + if (r) + return r; + + if (count == 0) { + *fence = NULL; + return 0; + } + + if (count == 1) { + *fence = fences[0]; + kfree(fences); + return 0; + } + + array = dma_fence_array_create(count, fences, + dma_fence_context_alloc(1), + 1, false); + if (!array) { + while (count--) + dma_fence_put(fences[count]); + kfree(fences); + return -ENOMEM; + } + + *fence = &array->base; + return 0; +} +EXPORT_SYMBOL_GPL(dma_resv_get_singleton); + +/** + * dma_resv_wait_timeout - Wait on reservation's objects fences + * @obj: the reservation object + * @usage: controls which fences to include, see enum dma_resv_usage. + * @intr: if true, do interruptible wait + * @timeout: timeout value in jiffies or zero to return immediately + * + * Callers are not required to hold specific locks, but maybe hold + * dma_resv_lock() already + * RETURNS + * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or + * greater than zer on success. + */ +long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage, + bool intr, unsigned long timeout) +{ + long ret = timeout ? timeout : 1; + struct dma_resv_iter cursor; + struct dma_fence *fence; + + dma_resv_iter_begin(&cursor, obj, usage); + dma_resv_for_each_fence_unlocked(&cursor, fence) { + + ret = dma_fence_wait_timeout(fence, intr, ret); + if (ret <= 0) { + dma_resv_iter_end(&cursor); + return ret; + } + } + dma_resv_iter_end(&cursor); + + return ret; +} +EXPORT_SYMBOL_GPL(dma_resv_wait_timeout); + + +/** + * dma_resv_test_signaled - Test if a reservation object's fences have been + * signaled. + * @obj: the reservation object + * @usage: controls which fences to include, see enum dma_resv_usage. + * + * Callers are not required to hold specific locks, but maybe hold + * dma_resv_lock() already. + * + * RETURNS + * + * True if all fences signaled, else false. + */ +bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage) +{ + struct dma_resv_iter cursor; + struct dma_fence *fence; + + dma_resv_iter_begin(&cursor, obj, usage); + dma_resv_for_each_fence_unlocked(&cursor, fence) { + dma_resv_iter_end(&cursor); + return false; + } + dma_resv_iter_end(&cursor); + return true; +} +EXPORT_SYMBOL_GPL(dma_resv_test_signaled); + +/** + * dma_resv_describe - Dump description of the resv object into seq_file + * @obj: the reservation object + * @seq: the seq_file to dump the description into + * + * Dump a textual description of the fences inside an dma_resv object into the + * seq_file. + */ +void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq) +{ + static const char *usage[] = { "kernel", "write", "read", "bookkeep" }; + struct dma_resv_iter cursor; + struct dma_fence *fence; + + dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) { + seq_printf(seq, "\t%s fence:", + usage[dma_resv_iter_usage(&cursor)]); + dma_fence_describe(fence, seq); + } +} +EXPORT_SYMBOL_GPL(dma_resv_describe); + +#if IS_ENABLED(CONFIG_LOCKDEP) +static int __init dma_resv_lockdep(void) +{ + struct mm_struct *mm = mm_alloc(); + struct ww_acquire_ctx ctx; + struct dma_resv obj; + struct address_space mapping; + int ret; + + if (!mm) + return -ENOMEM; + + dma_resv_init(&obj); + address_space_init_once(&mapping); + + mmap_read_lock(mm); + ww_acquire_init(&ctx, &reservation_ww_class); + ret = dma_resv_lock(&obj, &ctx); + if (ret == -EDEADLK) + dma_resv_lock_slow(&obj, &ctx); + fs_reclaim_acquire(GFP_KERNEL); + /* for unmap_mapping_range on trylocked buffer objects in shrinkers */ + i_mmap_lock_write(&mapping); + i_mmap_unlock_write(&mapping); +#ifdef CONFIG_MMU_NOTIFIER + lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); + __dma_fence_might_wait(); + lock_map_release(&__mmu_notifier_invalidate_range_start_map); +#else + __dma_fence_might_wait(); +#endif + fs_reclaim_release(GFP_KERNEL); + ww_mutex_unlock(&obj.lock); + ww_acquire_fini(&ctx); + mmap_read_unlock(mm); + + mmput(mm); + + return 0; +} +subsys_initcall(dma_resv_lockdep); +#endif |