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-rw-r--r--drivers/dma-buf/dma-resv.c779
1 files changed, 779 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
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index 000000000..e78ff9333
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+++ b/drivers/dma-buf/dma-resv.c
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+// 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