/*
   * drivers/dma-buf/sync_file.c
   *
   * Copyright (C) 2012 Google, Inc.
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   */
  
  #include <linux/export.h>
  #include <linux/file.h>
  #include <linux/fs.h>
  #include <linux/kernel.h>
  #include <linux/poll.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/uaccess.h>
  #include <linux/anon_inodes.h>

  #include <linux/sync_file.h>
  #include <uapi/linux/sync_file.h>

  
  static const struct file_operations sync_file_fops;

  static struct sync_file *sync_file_alloc(void)

  {
  	struct sync_file *sync_file;

  	sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);

  	if (!sync_file)
  		return NULL;
  
  	sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
  					     sync_file, 0);
  	if (IS_ERR(sync_file->file))
  		goto err;
  
  	kref_init(&sync_file->kref);
  
  	init_waitqueue_head(&sync_file->wq);

  	INIT_LIST_HEAD(&sync_file->cb.node);

  	return sync_file;
  
  err:
  	kfree(sync_file);
  	return NULL;
  }
  
  static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
  {

  	struct sync_file *sync_file;

  	sync_file = container_of(cb, struct sync_file, cb);

  	wake_up_all(&sync_file->wq);

  }
  
  /**

   * sync_file_create() - creates a sync file

   * @fence:	fence to add to the sync_fence
   *
   * Creates a sync_file containg @fence. Once this is called, the sync_file

   * takes ownership of @fence. The sync_file can be released with
   * fput(sync_file->file). Returns the sync_file or NULL in case of error.

   */
  struct sync_file *sync_file_create(struct fence *fence)
  {
  	struct sync_file *sync_file;

  	sync_file = sync_file_alloc();

  	if (!sync_file)
  		return NULL;

  	sync_file->fence = fence;

  	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",

  		 fence->ops->get_driver_name(fence),
  		 fence->ops->get_timeline_name(fence), fence->context,
  		 fence->seqno);

  	return sync_file;
  }
  EXPORT_SYMBOL(sync_file_create);
  
  /**
   * sync_file_fdget() - get a sync_file from an fd
   * @fd:		fd referencing a fence
   *
   * Ensures @fd references a valid sync_file, increments the refcount of the
   * backing file. Returns the sync_file or NULL in case of error.
   */
  static struct sync_file *sync_file_fdget(int fd)
  {
  	struct file *file = fget(fd);
  
  	if (!file)
  		return NULL;
  
  	if (file->f_op != &sync_file_fops)
  		goto err;
  
  	return file->private_data;
  
  err:
  	fput(file);
  	return NULL;
  }

  /**
   * sync_file_get_fence - get the fence related to the sync_file fd
   * @fd:		sync_file fd to get the fence from
   *
   * Ensures @fd references a valid sync_file and returns a fence that
   * represents all fence in the sync_file. On error NULL is returned.
   */
  struct fence *sync_file_get_fence(int fd)
  {
  	struct sync_file *sync_file;
  	struct fence *fence;
  
  	sync_file = sync_file_fdget(fd);
  	if (!sync_file)
  		return NULL;
  
  	fence = fence_get(sync_file->fence);
  	fput(sync_file->file);
  
  	return fence;
  }
  EXPORT_SYMBOL(sync_file_get_fence);

  static int sync_file_set_fence(struct sync_file *sync_file,
  			       struct fence **fences, int num_fences)

  {

  	struct fence_array *array;
  
  	/*
  	 * The reference for the fences in the new sync_file and held
  	 * in add_fence() during the merge procedure, so for num_fences == 1
  	 * we already own a new reference to the fence. For num_fence > 1
  	 * we own the reference of the fence_array creation.
  	 */
  	if (num_fences == 1) {
  		sync_file->fence = fences[0];

  		kfree(fences);

  	} else {
  		array = fence_array_create(num_fences, fences,
  					   fence_context_alloc(1), 1, false);
  		if (!array)
  			return -ENOMEM;
  
  		sync_file->fence = &array->base;
  	}

  	return 0;
  }
  
  static struct fence **get_fences(struct sync_file *sync_file, int *num_fences)
  {
  	if (fence_is_array(sync_file->fence)) {
  		struct fence_array *array = to_fence_array(sync_file->fence);
  
  		*num_fences = array->num_fences;
  		return array->fences;
  	}
  
  	*num_fences = 1;
  	return &sync_file->fence;
  }
  
  static void add_fence(struct fence **fences, int *i, struct fence *fence)
  {
  	fences[*i] = fence;
  
  	if (!fence_is_signaled(fence)) {

  		fence_get(fence);
  		(*i)++;
  	}
  }
  
  /**
   * sync_file_merge() - merge two sync_files
   * @name:	name of new fence
   * @a:		sync_file a
   * @b:		sync_file b
   *
   * Creates a new sync_file which contains copies of all the fences in both
   * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
   * new merged sync_file or NULL in case of error.
   */
  static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
  					 struct sync_file *b)
  {

  	struct sync_file *sync_file;

  	struct fence **fences, **nfences, **a_fences, **b_fences;
  	int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;

  	sync_file = sync_file_alloc();

  	if (!sync_file)
  		return NULL;

  	a_fences = get_fences(a, &a_num_fences);
  	b_fences = get_fences(b, &b_num_fences);
  	if (a_num_fences > INT_MAX - b_num_fences)
  		return NULL;
  
  	num_fences = a_num_fences + b_num_fences;
  
  	fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
  	if (!fences)
  		goto err;

  
  	/*
  	 * Assume sync_file a and b are both ordered and have no
  	 * duplicates with the same context.
  	 *
  	 * If a sync_file can only be created with sync_file_merge
  	 * and sync_file_create, this is a reasonable assumption.
  	 */

  	for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
  		struct fence *pt_a = a_fences[i_a];
  		struct fence *pt_b = b_fences[i_b];

  
  		if (pt_a->context < pt_b->context) {

  			add_fence(fences, &i, pt_a);

  
  			i_a++;
  		} else if (pt_a->context > pt_b->context) {

  			add_fence(fences, &i, pt_b);

  
  			i_b++;
  		} else {
  			if (pt_a->seqno - pt_b->seqno <= INT_MAX)

  				add_fence(fences, &i, pt_a);

  			else

  				add_fence(fences, &i, pt_b);

  
  			i_a++;
  			i_b++;
  		}
  	}

  	for (; i_a < a_num_fences; i_a++)
  		add_fence(fences, &i, a_fences[i_a]);
  
  	for (; i_b < b_num_fences; i_b++)
  		add_fence(fences, &i, b_fences[i_b]);

  	if (i == 0)
  		fences[i++] = fence_get(a_fences[0]);

  	if (num_fences > i) {
  		nfences = krealloc(fences, i * sizeof(*fences),
  				  GFP_KERNEL);
  		if (!nfences)
  			goto err;
  
  		fences = nfences;
  	}
  
  	if (sync_file_set_fence(sync_file, fences, i) < 0) {
  		kfree(fences);
  		goto err;
  	}

  	strlcpy(sync_file->name, name, sizeof(sync_file->name));
  	return sync_file;

  
  err:
  	fput(sync_file->file);
  	return NULL;

  }
  
  static void sync_file_free(struct kref *kref)
  {
  	struct sync_file *sync_file = container_of(kref, struct sync_file,
  						     kref);

  	if (test_bit(POLL_ENABLED, &sync_file->fence->flags))
  		fence_remove_callback(sync_file->fence, &sync_file->cb);

  	fence_put(sync_file->fence);

  	kfree(sync_file);
  }
  
  static int sync_file_release(struct inode *inode, struct file *file)
  {
  	struct sync_file *sync_file = file->private_data;
  
  	kref_put(&sync_file->kref, sync_file_free);
  	return 0;
  }
  
  static unsigned int sync_file_poll(struct file *file, poll_table *wait)
  {
  	struct sync_file *sync_file = file->private_data;

  
  	poll_wait(file, &sync_file->wq, wait);

  	if (!poll_does_not_wait(wait) &&
  	    !test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) {

  		if (fence_add_callback(sync_file->fence, &sync_file->cb,
  				       fence_check_cb_func) < 0)
  			wake_up_all(&sync_file->wq);
  	}

  	return fence_is_signaled(sync_file->fence) ? POLLIN : 0;

  }
  
  static long sync_file_ioctl_merge(struct sync_file *sync_file,

  				  unsigned long arg)

  {
  	int fd = get_unused_fd_flags(O_CLOEXEC);
  	int err;
  	struct sync_file *fence2, *fence3;
  	struct sync_merge_data data;
  
  	if (fd < 0)
  		return fd;
  
  	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
  		err = -EFAULT;
  		goto err_put_fd;
  	}
  
  	if (data.flags || data.pad) {
  		err = -EINVAL;
  		goto err_put_fd;
  	}
  
  	fence2 = sync_file_fdget(data.fd2);
  	if (!fence2) {
  		err = -ENOENT;
  		goto err_put_fd;
  	}
  
  	data.name[sizeof(data.name) - 1] = '\0';
  	fence3 = sync_file_merge(data.name, sync_file, fence2);
  	if (!fence3) {
  		err = -ENOMEM;
  		goto err_put_fence2;
  	}
  
  	data.fence = fd;
  	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
  		err = -EFAULT;
  		goto err_put_fence3;
  	}
  
  	fd_install(fd, fence3->file);
  	fput(fence2->file);
  	return 0;
  
  err_put_fence3:
  	fput(fence3->file);
  
  err_put_fence2:
  	fput(fence2->file);
  
  err_put_fd:
  	put_unused_fd(fd);
  	return err;
  }
  
  static void sync_fill_fence_info(struct fence *fence,

  				 struct sync_fence_info *info)

  {
  	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
  		sizeof(info->obj_name));
  	strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
  		sizeof(info->driver_name));
  	if (fence_is_signaled(fence))
  		info->status = fence->status >= 0 ? 1 : fence->status;
  	else
  		info->status = 0;
  	info->timestamp_ns = ktime_to_ns(fence->timestamp);
  }
  
  static long sync_file_ioctl_fence_info(struct sync_file *sync_file,

  				       unsigned long arg)

  {
  	struct sync_file_info info;
  	struct sync_fence_info *fence_info = NULL;

  	struct fence **fences;

  	__u32 size;

  	int num_fences, ret, i;

  
  	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
  		return -EFAULT;
  
  	if (info.flags || info.pad)
  		return -EINVAL;

  	fences = get_fences(sync_file, &num_fences);

  	/*
  	 * Passing num_fences = 0 means that userspace doesn't want to
  	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
  	 * sync_fence_info and return the actual number of fences on
  	 * info->num_fences.
  	 */
  	if (!info.num_fences)
  		goto no_fences;

  	if (info.num_fences < num_fences)

  		return -EINVAL;

  	size = num_fences * sizeof(*fence_info);

  	fence_info = kzalloc(size, GFP_KERNEL);
  	if (!fence_info)
  		return -ENOMEM;

  	for (i = 0; i < num_fences; i++)
  		sync_fill_fence_info(fences[i], &fence_info[i]);

  
  	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
  			 size)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  no_fences:
  	strlcpy(info.name, sync_file->name, sizeof(info.name));

  	info.status = fence_is_signaled(sync_file->fence);
  	info.num_fences = num_fences;

  
  	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
  		ret = -EFAULT;
  	else
  		ret = 0;
  
  out:
  	kfree(fence_info);
  
  	return ret;
  }
  
  static long sync_file_ioctl(struct file *file, unsigned int cmd,

  			    unsigned long arg)

  {
  	struct sync_file *sync_file = file->private_data;
  
  	switch (cmd) {
  	case SYNC_IOC_MERGE:
  		return sync_file_ioctl_merge(sync_file, arg);
  
  	case SYNC_IOC_FILE_INFO:
  		return sync_file_ioctl_fence_info(sync_file, arg);
  
  	default:
  		return -ENOTTY;
  	}
  }
  
  static const struct file_operations sync_file_fops = {
  	.release = sync_file_release,
  	.poll = sync_file_poll,
  	.unlocked_ioctl = sync_file_ioctl,
  	.compat_ioctl = sync_file_ioctl,
  };