Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 794 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vmwgfx/ttm_object.c b/drivers/gpu/drm/vmwgfx/ttm_object.c
new file mode 100644
index 000000000..16077785a
--- /dev/null
+++ b/drivers/gpu/drm/vmwgfx/ttm_object.c
@@ -0,0 +1,794 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/**************************************************************************
+ *
+ * Copyright (c) 2009-2013 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>
+ *
+ * While no substantial code is shared, the prime code is inspired by
+ * drm_prime.c, with
+ * Authors:
+ *      Dave Airlie <airlied@redhat.com>
+ *      Rob Clark <rob.clark@linaro.org>
+ */
+/** @file ttm_ref_object.c
+ *
+ * Base- and reference object implementation for the various
+ * ttm objects. Implements reference counting, minimal security checks
+ * and release on file close.
+ */
+
+
+/**
+ * struct ttm_object_file
+ *
+ * @tdev: Pointer to the ttm_object_device.
+ *
+ * @lock: Lock that protects the ref_list list and the
+ * ref_hash hash tables.
+ *
+ * @ref_list: List of ttm_ref_objects to be destroyed at
+ * file release.
+ *
+ * @ref_hash: Hash tables of ref objects, one per ttm_ref_type,
+ * for fast lookup of ref objects given a base object.
+ */
+
+#define pr_fmt(fmt) "[TTM] " fmt
+
+#include <drm/ttm/ttm_module.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/atomic.h>
+#include "ttm_object.h"
+
+struct ttm_object_file {
+	struct ttm_object_device *tdev;
+	spinlock_t lock;
+	struct list_head ref_list;
+	struct drm_open_hash ref_hash[TTM_REF_NUM];
+	struct kref refcount;
+};
+
+/**
+ * struct ttm_object_device
+ *
+ * @object_lock: lock that protects the object_hash hash table.
+ *
+ * @object_hash: hash table for fast lookup of object global names.
+ *
+ * @object_count: Per device object count.
+ *
+ * This is the per-device data structure needed for ttm object management.
+ */
+
+struct ttm_object_device {
+	spinlock_t object_lock;
+	struct drm_open_hash object_hash;
+	atomic_t object_count;
+	struct ttm_mem_global *mem_glob;
+	struct dma_buf_ops ops;
+	void (*dmabuf_release)(struct dma_buf *dma_buf);
+	size_t dma_buf_size;
+	struct idr idr;
+};
+
+/**
+ * struct ttm_ref_object
+ *
+ * @hash: Hash entry for the per-file object reference hash.
+ *
+ * @head: List entry for the per-file list of ref-objects.
+ *
+ * @kref: Ref count.
+ *
+ * @obj: Base object this ref object is referencing.
+ *
+ * @ref_type: Type of ref object.
+ *
+ * This is similar to an idr object, but it also has a hash table entry
+ * that allows lookup with a pointer to the referenced object as a key. In
+ * that way, one can easily detect whether a base object is referenced by
+ * a particular ttm_object_file. It also carries a ref count to avoid creating
+ * multiple ref objects if a ttm_object_file references the same base
+ * object more than once.
+ */
+
+struct ttm_ref_object {
+	struct rcu_head rcu_head;
+	struct drm_hash_item hash;
+	struct list_head head;
+	struct kref kref;
+	enum ttm_ref_type ref_type;
+	struct ttm_base_object *obj;
+	struct ttm_object_file *tfile;
+};
+
+static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf);
+
+static inline struct ttm_object_file *
+ttm_object_file_ref(struct ttm_object_file *tfile)
+{
+	kref_get(&tfile->refcount);
+	return tfile;
+}
+
+static void ttm_object_file_destroy(struct kref *kref)
+{
+	struct ttm_object_file *tfile =
+		container_of(kref, struct ttm_object_file, refcount);
+
+	kfree(tfile);
+}
+
+
+static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)
+{
+	struct ttm_object_file *tfile = *p_tfile;
+
+	*p_tfile = NULL;
+	kref_put(&tfile->refcount, ttm_object_file_destroy);
+}
+
+
+int ttm_base_object_init(struct ttm_object_file *tfile,
+			 struct ttm_base_object *base,
+			 bool shareable,
+			 enum ttm_object_type object_type,
+			 void (*refcount_release) (struct ttm_base_object **),
+			 void (*ref_obj_release) (struct ttm_base_object *,
+						  enum ttm_ref_type ref_type))
+{
+	struct ttm_object_device *tdev = tfile->tdev;
+	int ret;
+
+	base->shareable = shareable;
+	base->tfile = ttm_object_file_ref(tfile);
+	base->refcount_release = refcount_release;
+	base->ref_obj_release = ref_obj_release;
+	base->object_type = object_type;
+	kref_init(&base->refcount);
+	idr_preload(GFP_KERNEL);
+	spin_lock(&tdev->object_lock);
+	ret = idr_alloc(&tdev->idr, base, 1, 0, GFP_NOWAIT);
+	spin_unlock(&tdev->object_lock);
+	idr_preload_end();
+	if (ret < 0)
+		return ret;
+
+	base->handle = ret;
+	ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);
+	if (unlikely(ret != 0))
+		goto out_err1;
+
+	ttm_base_object_unref(&base);
+
+	return 0;
+out_err1:
+	spin_lock(&tdev->object_lock);
+	idr_remove(&tdev->idr, base->handle);
+	spin_unlock(&tdev->object_lock);
+	return ret;
+}
+
+static void ttm_release_base(struct kref *kref)
+{
+	struct ttm_base_object *base =
+	    container_of(kref, struct ttm_base_object, refcount);
+	struct ttm_object_device *tdev = base->tfile->tdev;
+
+	spin_lock(&tdev->object_lock);
+	idr_remove(&tdev->idr, base->handle);
+	spin_unlock(&tdev->object_lock);
+
+	/*
+	 * Note: We don't use synchronize_rcu() here because it's far
+	 * too slow. It's up to the user to free the object using
+	 * call_rcu() or ttm_base_object_kfree().
+	 */
+
+	ttm_object_file_unref(&base->tfile);
+	if (base->refcount_release)
+		base->refcount_release(&base);
+}
+
+void ttm_base_object_unref(struct ttm_base_object **p_base)
+{
+	struct ttm_base_object *base = *p_base;
+
+	*p_base = NULL;
+
+	kref_put(&base->refcount, ttm_release_base);
+}
+
+/**
+ * ttm_base_object_noref_lookup - look up a base object without reference
+ * @tfile: The struct ttm_object_file the object is registered with.
+ * @key: The object handle.
+ *
+ * This function looks up a ttm base object and returns a pointer to it
+ * without refcounting the pointer. The returned pointer is only valid
+ * until ttm_base_object_noref_release() is called, and the object
+ * pointed to by the returned pointer may be doomed. Any persistent usage
+ * of the object requires a refcount to be taken using kref_get_unless_zero().
+ * Iff this function returns successfully it needs to be paired with
+ * ttm_base_object_noref_release() and no sleeping- or scheduling functions
+ * may be called inbetween these function callse.
+ *
+ * Return: A pointer to the object if successful or NULL otherwise.
+ */
+struct ttm_base_object *
+ttm_base_object_noref_lookup(struct ttm_object_file *tfile, uint32_t key)
+{
+	struct drm_hash_item *hash;
+	struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];
+	int ret;
+
+	rcu_read_lock();
+	ret = drm_ht_find_item_rcu(ht, key, &hash);
+	if (ret) {
+		rcu_read_unlock();
+		return NULL;
+	}
+
+	__release(RCU);
+	return drm_hash_entry(hash, struct ttm_ref_object, hash)->obj;
+}
+EXPORT_SYMBOL(ttm_base_object_noref_lookup);
+
+struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
+					       uint32_t key)
+{
+	struct ttm_base_object *base = NULL;
+	struct drm_hash_item *hash;
+	struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];
+	int ret;
+
+	rcu_read_lock();
+	ret = drm_ht_find_item_rcu(ht, key, &hash);
+
+	if (likely(ret == 0)) {
+		base = drm_hash_entry(hash, struct ttm_ref_object, hash)->obj;
+		if (!kref_get_unless_zero(&base->refcount))
+			base = NULL;
+	}
+	rcu_read_unlock();
+
+	return base;
+}
+
+struct ttm_base_object *
+ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key)
+{
+	struct ttm_base_object *base;
+
+	rcu_read_lock();
+	base = idr_find(&tdev->idr, key);
+
+	if (base && !kref_get_unless_zero(&base->refcount))
+		base = NULL;
+	rcu_read_unlock();
+
+	return base;
+}
+
+/**
+ * ttm_ref_object_exists - Check whether a caller has a valid ref object
+ * (has opened) a base object.
+ *
+ * @tfile: Pointer to a struct ttm_object_file identifying the caller.
+ * @base: Pointer to a struct base object.
+ *
+ * Checks wether the caller identified by @tfile has put a valid USAGE
+ * reference object on the base object identified by @base.
+ */
+bool ttm_ref_object_exists(struct ttm_object_file *tfile,
+			   struct ttm_base_object *base)
+{
+	struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];
+	struct drm_hash_item *hash;
+	struct ttm_ref_object *ref;
+
+	rcu_read_lock();
+	if (unlikely(drm_ht_find_item_rcu(ht, base->handle, &hash) != 0))
+		goto out_false;
+
+	/*
+	 * Verify that the ref object is really pointing to our base object.
+	 * Our base object could actually be dead, and the ref object pointing
+	 * to another base object with the same handle.
+	 */
+	ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
+	if (unlikely(base != ref->obj))
+		goto out_false;
+
+	/*
+	 * Verify that the ref->obj pointer was actually valid!
+	 */
+	rmb();
+	if (unlikely(kref_read(&ref->kref) == 0))
+		goto out_false;
+
+	rcu_read_unlock();
+	return true;
+
+ out_false:
+	rcu_read_unlock();
+	return false;
+}
+
+int ttm_ref_object_add(struct ttm_object_file *tfile,
+		       struct ttm_base_object *base,
+		       enum ttm_ref_type ref_type, bool *existed,
+		       bool require_existed)
+{
+	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
+	struct ttm_ref_object *ref;
+	struct drm_hash_item *hash;
+	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
+	struct ttm_operation_ctx ctx = {
+		.interruptible = false,
+		.no_wait_gpu = false
+	};
+	int ret = -EINVAL;
+
+	if (base->tfile != tfile && !base->shareable)
+		return -EPERM;
+
+	if (existed != NULL)
+		*existed = true;
+
+	while (ret == -EINVAL) {
+		rcu_read_lock();
+		ret = drm_ht_find_item_rcu(ht, base->handle, &hash);
+
+		if (ret == 0) {
+			ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
+			if (kref_get_unless_zero(&ref->kref)) {
+				rcu_read_unlock();
+				break;
+			}
+		}
+
+		rcu_read_unlock();
+		if (require_existed)
+			return -EPERM;
+
+		ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),
+					   &ctx);
+		if (unlikely(ret != 0))
+			return ret;
+		ref = kmalloc(sizeof(*ref), GFP_KERNEL);
+		if (unlikely(ref == NULL)) {
+			ttm_mem_global_free(mem_glob, sizeof(*ref));
+			return -ENOMEM;
+		}
+
+		ref->hash.key = base->handle;
+		ref->obj = base;
+		ref->tfile = tfile;
+		ref->ref_type = ref_type;
+		kref_init(&ref->kref);
+
+		spin_lock(&tfile->lock);
+		ret = drm_ht_insert_item_rcu(ht, &ref->hash);
+
+		if (likely(ret == 0)) {
+			list_add_tail(&ref->head, &tfile->ref_list);
+			kref_get(&base->refcount);
+			spin_unlock(&tfile->lock);
+			if (existed != NULL)
+				*existed = false;
+			break;
+		}
+
+		spin_unlock(&tfile->lock);
+		BUG_ON(ret != -EINVAL);
+
+		ttm_mem_global_free(mem_glob, sizeof(*ref));
+		kfree(ref);
+	}
+
+	return ret;
+}
+
+static void __releases(tfile->lock) __acquires(tfile->lock)
+ttm_ref_object_release(struct kref *kref)
+{
+	struct ttm_ref_object *ref =
+	    container_of(kref, struct ttm_ref_object, kref);
+	struct ttm_base_object *base = ref->obj;
+	struct ttm_object_file *tfile = ref->tfile;
+	struct drm_open_hash *ht;
+	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
+
+	ht = &tfile->ref_hash[ref->ref_type];
+	(void)drm_ht_remove_item_rcu(ht, &ref->hash);
+	list_del(&ref->head);
+	spin_unlock(&tfile->lock);
+
+	if (ref->ref_type != TTM_REF_USAGE && base->ref_obj_release)
+		base->ref_obj_release(base, ref->ref_type);
+
+	ttm_base_object_unref(&ref->obj);
+	ttm_mem_global_free(mem_glob, sizeof(*ref));
+	kfree_rcu(ref, rcu_head);
+	spin_lock(&tfile->lock);
+}
+
+int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
+			      unsigned long key, enum ttm_ref_type ref_type)
+{
+	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
+	struct ttm_ref_object *ref;
+	struct drm_hash_item *hash;
+	int ret;
+
+	spin_lock(&tfile->lock);
+	ret = drm_ht_find_item(ht, key, &hash);
+	if (unlikely(ret != 0)) {
+		spin_unlock(&tfile->lock);
+		return -EINVAL;
+	}
+	ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
+	kref_put(&ref->kref, ttm_ref_object_release);
+	spin_unlock(&tfile->lock);
+	return 0;
+}
+
+void ttm_object_file_release(struct ttm_object_file **p_tfile)
+{
+	struct ttm_ref_object *ref;
+	struct list_head *list;
+	unsigned int i;
+	struct ttm_object_file *tfile = *p_tfile;
+
+	*p_tfile = NULL;
+	spin_lock(&tfile->lock);
+
+	/*
+	 * Since we release the lock within the loop, we have to
+	 * restart it from the beginning each time.
+	 */
+
+	while (!list_empty(&tfile->ref_list)) {
+		list = tfile->ref_list.next;
+		ref = list_entry(list, struct ttm_ref_object, head);
+		ttm_ref_object_release(&ref->kref);
+	}
+
+	spin_unlock(&tfile->lock);
+	for (i = 0; i < TTM_REF_NUM; ++i)
+		drm_ht_remove(&tfile->ref_hash[i]);
+
+	ttm_object_file_unref(&tfile);
+}
+
+struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev,
+					     unsigned int hash_order)
+{
+	struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);
+	unsigned int i;
+	unsigned int j = 0;
+	int ret;
+
+	if (unlikely(tfile == NULL))
+		return NULL;
+
+	spin_lock_init(&tfile->lock);
+	tfile->tdev = tdev;
+	kref_init(&tfile->refcount);
+	INIT_LIST_HEAD(&tfile->ref_list);
+
+	for (i = 0; i < TTM_REF_NUM; ++i) {
+		ret = drm_ht_create(&tfile->ref_hash[i], hash_order);
+		if (ret) {
+			j = i;
+			goto out_err;
+		}
+	}
+
+	return tfile;
+out_err:
+	for (i = 0; i < j; ++i)
+		drm_ht_remove(&tfile->ref_hash[i]);
+
+	kfree(tfile);
+
+	return NULL;
+}
+
+struct ttm_object_device *
+ttm_object_device_init(struct ttm_mem_global *mem_glob,
+		       unsigned int hash_order,
+		       const struct dma_buf_ops *ops)
+{
+	struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);
+	int ret;
+
+	if (unlikely(tdev == NULL))
+		return NULL;
+
+	tdev->mem_glob = mem_glob;
+	spin_lock_init(&tdev->object_lock);
+	atomic_set(&tdev->object_count, 0);
+	ret = drm_ht_create(&tdev->object_hash, hash_order);
+	if (ret != 0)
+		goto out_no_object_hash;
+
+	idr_init(&tdev->idr);
+	tdev->ops = *ops;
+	tdev->dmabuf_release = tdev->ops.release;
+	tdev->ops.release = ttm_prime_dmabuf_release;
+	tdev->dma_buf_size = ttm_round_pot(sizeof(struct dma_buf)) +
+		ttm_round_pot(sizeof(struct file));
+	return tdev;
+
+out_no_object_hash:
+	kfree(tdev);
+	return NULL;
+}
+
+void ttm_object_device_release(struct ttm_object_device **p_tdev)
+{
+	struct ttm_object_device *tdev = *p_tdev;
+
+	*p_tdev = NULL;
+
+	WARN_ON_ONCE(!idr_is_empty(&tdev->idr));
+	idr_destroy(&tdev->idr);
+	drm_ht_remove(&tdev->object_hash);
+
+	kfree(tdev);
+}
+
+/**
+ * get_dma_buf_unless_doomed - get a dma_buf reference if possible.
+ *
+ * @dma_buf: Non-refcounted pointer to a struct dma-buf.
+ *
+ * Obtain a file reference from a lookup structure that doesn't refcount
+ * the file, but synchronizes with its release method to make sure it has
+ * not been freed yet. See for example kref_get_unless_zero documentation.
+ * Returns true if refcounting succeeds, false otherwise.
+ *
+ * Nobody really wants this as a public API yet, so let it mature here
+ * for some time...
+ */
+static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)
+{
+	return atomic_long_inc_not_zero(&dmabuf->file->f_count) != 0L;
+}
+
+/**
+ * ttm_prime_refcount_release - refcount release method for a prime object.
+ *
+ * @p_base: Pointer to ttm_base_object pointer.
+ *
+ * This is a wrapper that calls the refcount_release founction of the
+ * underlying object. At the same time it cleans up the prime object.
+ * This function is called when all references to the base object we
+ * derive from are gone.
+ */
+static void ttm_prime_refcount_release(struct ttm_base_object **p_base)
+{
+	struct ttm_base_object *base = *p_base;
+	struct ttm_prime_object *prime;
+
+	*p_base = NULL;
+	prime = container_of(base, struct ttm_prime_object, base);
+	BUG_ON(prime->dma_buf != NULL);
+	mutex_destroy(&prime->mutex);
+	if (prime->refcount_release)
+		prime->refcount_release(&base);
+}
+
+/**
+ * ttm_prime_dmabuf_release - Release method for the dma-bufs we export
+ *
+ * @dma_buf:
+ *
+ * This function first calls the dma_buf release method the driver
+ * provides. Then it cleans up our dma_buf pointer used for lookup,
+ * and finally releases the reference the dma_buf has on our base
+ * object.
+ */
+static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf)
+{
+	struct ttm_prime_object *prime =
+		(struct ttm_prime_object *) dma_buf->priv;
+	struct ttm_base_object *base = &prime->base;
+	struct ttm_object_device *tdev = base->tfile->tdev;
+
+	if (tdev->dmabuf_release)
+		tdev->dmabuf_release(dma_buf);
+	mutex_lock(&prime->mutex);
+	if (prime->dma_buf == dma_buf)
+		prime->dma_buf = NULL;
+	mutex_unlock(&prime->mutex);
+	ttm_mem_global_free(tdev->mem_glob, tdev->dma_buf_size);
+	ttm_base_object_unref(&base);
+}
+
+/**
+ * ttm_prime_fd_to_handle - Get a base object handle from a prime fd
+ *
+ * @tfile: A struct ttm_object_file identifying the caller.
+ * @fd: The prime / dmabuf fd.
+ * @handle: The returned handle.
+ *
+ * This function returns a handle to an object that previously exported
+ * a dma-buf. Note that we don't handle imports yet, because we simply
+ * have no consumers of that implementation.
+ */
+int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
+			   int fd, u32 *handle)
+{
+	struct ttm_object_device *tdev = tfile->tdev;
+	struct dma_buf *dma_buf;
+	struct ttm_prime_object *prime;
+	struct ttm_base_object *base;
+	int ret;
+
+	dma_buf = dma_buf_get(fd);
+	if (IS_ERR(dma_buf))
+		return PTR_ERR(dma_buf);
+
+	if (dma_buf->ops != &tdev->ops)
+		return -ENOSYS;
+
+	prime = (struct ttm_prime_object *) dma_buf->priv;
+	base = &prime->base;
+	*handle = base->handle;
+	ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);
+
+	dma_buf_put(dma_buf);
+
+	return ret;
+}
+
+/**
+ * ttm_prime_handle_to_fd - Return a dma_buf fd from a ttm prime object
+ *
+ * @tfile: Struct ttm_object_file identifying the caller.
+ * @handle: Handle to the object we're exporting from.
+ * @flags: flags for dma-buf creation. We just pass them on.
+ * @prime_fd: The returned file descriptor.
+ *
+ */
+int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
+			   uint32_t handle, uint32_t flags,
+			   int *prime_fd)
+{
+	struct ttm_object_device *tdev = tfile->tdev;
+	struct ttm_base_object *base;
+	struct dma_buf *dma_buf;
+	struct ttm_prime_object *prime;
+	int ret;
+
+	base = ttm_base_object_lookup(tfile, handle);
+	if (unlikely(base == NULL ||
+		     base->object_type != ttm_prime_type)) {
+		ret = -ENOENT;
+		goto out_unref;
+	}
+
+	prime = container_of(base, struct ttm_prime_object, base);
+	if (unlikely(!base->shareable)) {
+		ret = -EPERM;
+		goto out_unref;
+	}
+
+	ret = mutex_lock_interruptible(&prime->mutex);
+	if (unlikely(ret != 0)) {
+		ret = -ERESTARTSYS;
+		goto out_unref;
+	}
+
+	dma_buf = prime->dma_buf;
+	if (!dma_buf || !get_dma_buf_unless_doomed(dma_buf)) {
+		DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+		struct ttm_operation_ctx ctx = {
+			.interruptible = true,
+			.no_wait_gpu = false
+		};
+		exp_info.ops = &tdev->ops;
+		exp_info.size = prime->size;
+		exp_info.flags = flags;
+		exp_info.priv = prime;
+
+		/*
+		 * Need to create a new dma_buf, with memory accounting.
+		 */
+		ret = ttm_mem_global_alloc(tdev->mem_glob, tdev->dma_buf_size,
+					   &ctx);
+		if (unlikely(ret != 0)) {
+			mutex_unlock(&prime->mutex);
+			goto out_unref;
+		}
+
+		dma_buf = dma_buf_export(&exp_info);
+		if (IS_ERR(dma_buf)) {
+			ret = PTR_ERR(dma_buf);
+			ttm_mem_global_free(tdev->mem_glob,
+					    tdev->dma_buf_size);
+			mutex_unlock(&prime->mutex);
+			goto out_unref;
+		}
+
+		/*
+		 * dma_buf has taken the base object reference
+		 */
+		base = NULL;
+		prime->dma_buf = dma_buf;
+	}
+	mutex_unlock(&prime->mutex);
+
+	ret = dma_buf_fd(dma_buf, flags);
+	if (ret >= 0) {
+		*prime_fd = ret;
+		ret = 0;
+	} else
+		dma_buf_put(dma_buf);
+
+out_unref:
+	if (base)
+		ttm_base_object_unref(&base);
+	return ret;
+}
+
+/**
+ * ttm_prime_object_init - Initialize a ttm_prime_object
+ *
+ * @tfile: struct ttm_object_file identifying the caller
+ * @size: The size of the dma_bufs we export.
+ * @prime: The object to be initialized.
+ * @shareable: See ttm_base_object_init
+ * @type: See ttm_base_object_init
+ * @refcount_release: See ttm_base_object_init
+ * @ref_obj_release: See ttm_base_object_init
+ *
+ * Initializes an object which is compatible with the drm_prime model
+ * for data sharing between processes and devices.
+ */
+int ttm_prime_object_init(struct ttm_object_file *tfile, size_t size,
+			  struct ttm_prime_object *prime, bool shareable,
+			  enum ttm_object_type type,
+			  void (*refcount_release) (struct ttm_base_object **),
+			  void (*ref_obj_release) (struct ttm_base_object *,
+						   enum ttm_ref_type ref_type))
+{
+	mutex_init(&prime->mutex);
+	prime->size = PAGE_ALIGN(size);
+	prime->real_type = type;
+	prime->dma_buf = NULL;
+	prime->refcount_release = refcount_release;
+	return ttm_base_object_init(tfile, &prime->base, shareable,
+				    ttm_prime_type,
+				    ttm_prime_refcount_release,
+				    ref_obj_release);
+}