text: /*
   * videobuf2-core.c - video buffer 2 core framework
   *
   * Copyright (C) 2010 Samsung Electronics
   *
   * Author: Pawel Osciak <pawel@osciak.com>
   *	   Marek Szyprowski <m.szyprowski@samsung.com>
   *
   * The vb2_thread implementation was based on code from videobuf-dvb.c:
   *	(c) 2004 Gerd Knorr <kraxel@bytesex.org> [SUSE Labs]
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/err.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/mm.h>
  #include <linux/poll.h>
  #include <linux/slab.h>
  #include <linux/sched.h>
  #include <linux/freezer.h>
  #include <linux/kthread.h>
  
  #include <media/videobuf2-core.h>
  #include <media/v4l2-mc.h>
  
  #include <trace/events/vb2.h>
  
  static int debug;
  module_param(debug, int, 0644);
  
  #define dprintk(level, fmt, arg...)				\
  	do {							\
  		if (debug >= level)				\
  			pr_info("%s: " fmt, __func__, ## arg);	\
  	} while (0)
  
  #ifdef CONFIG_VIDEO_ADV_DEBUG
  
  /*
   * If advanced debugging is on, then count how often each op is called
   * successfully, which can either be per-buffer or per-queue.
   *
   * This makes it easy to check that the 'init' and 'cleanup'
   * (and variations thereof) stay balanced.
   */
  
  #define log_memop(vb, op)						\
  	dprintk(2, "call_memop(%p, %d, %s)%s\n",			\
  		(vb)->vb2_queue, (vb)->index, #op,			\
  		(vb)->vb2_queue->mem_ops->op ? "" : " (nop)")
  
  #define call_memop(vb, op, args...)					\
  ({									\
  	struct vb2_queue *_q = (vb)->vb2_queue;				\
  	int err;							\
  									\
  	log_memop(vb, op);						\
  	err = _q->mem_ops->op ? _q->mem_ops->op(args) : 0;		\
  	if (!err)							\
  		(vb)->cnt_mem_ ## op++;					\
  	err;								\
  })
  
  #define call_ptr_memop(vb, op, args...)					\
  ({									\
  	struct vb2_queue *_q = (vb)->vb2_queue;				\
  	void *ptr;							\
  									\
  	log_memop(vb, op);						\
  	ptr = _q->mem_ops->op ? _q->mem_ops->op(args) : NULL;		\
  	if (!IS_ERR_OR_NULL(ptr))					\
  		(vb)->cnt_mem_ ## op++;					\
  	ptr;								\
  })
  
  #define call_void_memop(vb, op, args...)				\
  ({									\
  	struct vb2_queue *_q = (vb)->vb2_queue;				\
  									\
  	log_memop(vb, op);						\
  	if (_q->mem_ops->op)						\
  		_q->mem_ops->op(args);					\
  	(vb)->cnt_mem_ ## op++;						\
  })
  
  #define log_qop(q, op)							\
  	dprintk(2, "call_qop(%p, %s)%s\n", q, #op,			\
  		(q)->ops->op ? "" : " (nop)")
  
  #define call_qop(q, op, args...)					\
  ({									\
  	int err;							\
  									\
  	log_qop(q, op);							\
  	err = (q)->ops->op ? (q)->ops->op(args) : 0;			\
  	if (!err)							\
  		(q)->cnt_ ## op++;					\
  	err;								\
  })
  
  #define call_void_qop(q, op, args...)					\
  ({									\
  	log_qop(q, op);							\
  	if ((q)->ops->op)						\
  		(q)->ops->op(args);					\
  	(q)->cnt_ ## op++;						\
  })
  
  #define log_vb_qop(vb, op, args...)					\
  	dprintk(2, "call_vb_qop(%p, %d, %s)%s\n",			\
  		(vb)->vb2_queue, (vb)->index, #op,			\
  		(vb)->vb2_queue->ops->op ? "" : " (nop)")
  
  #define call_vb_qop(vb, op, args...)					\
  ({									\
  	int err;							\
  									\
  	log_vb_qop(vb, op);						\
  	err = (vb)->vb2_queue->ops->op ?				\
  		(vb)->vb2_queue->ops->op(args) : 0;			\
  	if (!err)							\
  		(vb)->cnt_ ## op++;					\
  	err;								\
  })
  
  #define call_void_vb_qop(vb, op, args...)				\
  ({									\
  	log_vb_qop(vb, op);						\
  	if ((vb)->vb2_queue->ops->op)					\
  		(vb)->vb2_queue->ops->op(args);				\
  	(vb)->cnt_ ## op++;						\
  })
  
  #else
  
  #define call_memop(vb, op, args...)					\
  	((vb)->vb2_queue->mem_ops->op ?					\
  		(vb)->vb2_queue->mem_ops->op(args) : 0)
  
  #define call_ptr_memop(vb, op, args...)					\
  	((vb)->vb2_queue->mem_ops->op ?					\
  		(vb)->vb2_queue->mem_ops->op(args) : NULL)
  
  #define call_void_memop(vb, op, args...)				\
  	do {								\
  		if ((vb)->vb2_queue->mem_ops->op)			\
  			(vb)->vb2_queue->mem_ops->op(args);		\
  	} while (0)
  
  #define call_qop(q, op, args...)					\
  	((q)->ops->op ? (q)->ops->op(args) : 0)
  
  #define call_void_qop(q, op, args...)					\
  	do {								\
  		if ((q)->ops->op)					\
  			(q)->ops->op(args);				\
  	} while (0)
  
  #define call_vb_qop(vb, op, args...)					\
  	((vb)->vb2_queue->ops->op ? (vb)->vb2_queue->ops->op(args) : 0)
  
  #define call_void_vb_qop(vb, op, args...)				\
  	do {								\
  		if ((vb)->vb2_queue->ops->op)				\
  			(vb)->vb2_queue->ops->op(args);			\
  	} while (0)
  
  #endif
  
  #define call_bufop(q, op, args...)					\
  ({									\
  	int ret = 0;							\
  	if (q && q->buf_ops && q->buf_ops->op)				\
  		ret = q->buf_ops->op(args);				\
  	ret;								\
  })
  
  #define call_void_bufop(q, op, args...)					\
  ({									\
  	if (q && q->buf_ops && q->buf_ops->op)				\
  		q->buf_ops->op(args);					\
  })
  
  static void __vb2_queue_cancel(struct vb2_queue *q);
  static void __enqueue_in_driver(struct vb2_buffer *vb);
  
  /*
   * __vb2_buf_mem_alloc() - allocate video memory for the given buffer
   */
  static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  	void *mem_priv;
  	int plane;
  	int ret = -ENOMEM;
  
  	/*
  	 * Allocate memory for all planes in this buffer
  	 * NOTE: mmapped areas should be page aligned
  	 */
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		/* Memops alloc requires size to be page aligned. */
  		unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
  
  		/* Did it wrap around? */
  		if (size < vb->planes[plane].length)
  			goto free;
  
  		mem_priv = call_ptr_memop(vb, alloc,
  				q->alloc_devs[plane] ? : q->dev,
  				q->dma_attrs, size, q->dma_dir, q->gfp_flags);
  		if (IS_ERR_OR_NULL(mem_priv)) {
  			if (mem_priv)
  				ret = PTR_ERR(mem_priv);
  			goto free;
  		}
  
  		/* Associate allocator private data with this plane */
  		vb->planes[plane].mem_priv = mem_priv;
  	}
  
  	return 0;
  free:
  	/* Free already allocated memory if one of the allocations failed */
  	for (; plane > 0; --plane) {
  		call_void_memop(vb, put, vb->planes[plane - 1].mem_priv);
  		vb->planes[plane - 1].mem_priv = NULL;
  	}
  
  	return ret;
  }
  
  /*
   * __vb2_buf_mem_free() - free memory of the given buffer
   */
  static void __vb2_buf_mem_free(struct vb2_buffer *vb)
  {
  	unsigned int plane;
  
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		call_void_memop(vb, put, vb->planes[plane].mem_priv);
  		vb->planes[plane].mem_priv = NULL;
  		dprintk(3, "freed plane %d of buffer %d\n", plane, vb->index);
  	}
  }
  
  /*
   * __vb2_buf_userptr_put() - release userspace memory associated with
   * a USERPTR buffer
   */
  static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
  {
  	unsigned int plane;
  
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		if (vb->planes[plane].mem_priv)
  			call_void_memop(vb, put_userptr, vb->planes[plane].mem_priv);
  		vb->planes[plane].mem_priv = NULL;
  	}
  }
  
  /*
   * __vb2_plane_dmabuf_put() - release memory associated with
   * a DMABUF shared plane
   */
  static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb, struct vb2_plane *p)
  {
  	if (!p->mem_priv)
  		return;
  
  	if (p->dbuf_mapped)
  		call_void_memop(vb, unmap_dmabuf, p->mem_priv);
  
  	call_void_memop(vb, detach_dmabuf, p->mem_priv);
  	dma_buf_put(p->dbuf);
  	p->mem_priv = NULL;
  	p->dbuf = NULL;
  	p->dbuf_mapped = 0;
  }
  
  /*
   * __vb2_buf_dmabuf_put() - release memory associated with
   * a DMABUF shared buffer
   */
  static void __vb2_buf_dmabuf_put(struct vb2_buffer *vb)
  {
  	unsigned int plane;
  
  	for (plane = 0; plane < vb->num_planes; ++plane)
  		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
  }
  
  /*
   * __setup_offsets() - setup unique offsets ("cookies") for every plane in
   * the buffer.
   */
  static void __setup_offsets(struct vb2_buffer *vb)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  	unsigned int plane;
  	unsigned long off = 0;
  
  	if (vb->index) {
  		struct vb2_buffer *prev = q->bufs[vb->index - 1];
  		struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
  
  		off = PAGE_ALIGN(p->m.offset + p->length);
  	}
  
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		vb->planes[plane].m.offset = off;
  
  		dprintk(3, "buffer %d, plane %d offset 0x%08lx\n",
  				vb->index, plane, off);
  
  		off += vb->planes[plane].length;
  		off = PAGE_ALIGN(off);
  	}
  }
  
  /*
   * __vb2_queue_alloc() - allocate videobuf buffer structures and (for MMAP type)
   * video buffer memory for all buffers/planes on the queue and initializes the
   * queue
   *
   * Returns the number of buffers successfully allocated.
   */
  static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
  			     unsigned int num_buffers, unsigned int num_planes,
  			     const unsigned plane_sizes[VB2_MAX_PLANES])
  {
  	unsigned int buffer, plane;
  	struct vb2_buffer *vb;
  	int ret;
  
  	/* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
  	num_buffers = min_t(unsigned int, num_buffers,
  			    VB2_MAX_FRAME - q->num_buffers);
  
  	for (buffer = 0; buffer < num_buffers; ++buffer) {
  		/* Allocate videobuf buffer structures */
  		vb = kzalloc(q->buf_struct_size, GFP_KERNEL);
  		if (!vb) {
  			dprintk(1, "memory alloc for buffer struct failed\n");
  			break;
  		}
  
  		vb->state = VB2_BUF_STATE_DEQUEUED;
  		vb->vb2_queue = q;
  		vb->num_planes = num_planes;
  		vb->index = q->num_buffers + buffer;
  		vb->type = q->type;
  		vb->memory = memory;
  		for (plane = 0; plane < num_planes; ++plane) {
  			vb->planes[plane].length = plane_sizes[plane];
  			vb->planes[plane].min_length = plane_sizes[plane];
  		}
  		call_void_bufop(q, init_buffer, vb);
  
  		q->bufs[vb->index] = vb;
  
  		/* Allocate video buffer memory for the MMAP type */
  		if (memory == VB2_MEMORY_MMAP) {
  			ret = __vb2_buf_mem_alloc(vb);
  			if (ret) {
  				dprintk(1, "failed allocating memory for buffer %d\n",
  					buffer);
  				q->bufs[vb->index] = NULL;
  				kfree(vb);
  				break;
  			}
  			__setup_offsets(vb);
  			/*
  			 * Call the driver-provided buffer initialization
  			 * callback, if given. An error in initialization
  			 * results in queue setup failure.
  			 */
  			ret = call_vb_qop(vb, buf_init, vb);
  			if (ret) {
  				dprintk(1, "buffer %d %p initialization failed\n",
  					buffer, vb);
  				__vb2_buf_mem_free(vb);
  				q->bufs[vb->index] = NULL;
  				kfree(vb);
  				break;
  			}
  		}
  	}
  
  	dprintk(3, "allocated %d buffers, %d plane(s) each\n",
  		buffer, num_planes);
  
  	return buffer;
  }
  
  /*
   * __vb2_free_mem() - release all video buffer memory for a given queue
   */
  static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
  {
  	unsigned int buffer;
  	struct vb2_buffer *vb;
  
  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
  	     ++buffer) {
  		vb = q->bufs[buffer];
  		if (!vb)
  			continue;
  
  		/* Free MMAP buffers or release USERPTR buffers */
  		if (q->memory == VB2_MEMORY_MMAP)
  			__vb2_buf_mem_free(vb);
  		else if (q->memory == VB2_MEMORY_DMABUF)
  			__vb2_buf_dmabuf_put(vb);
  		else
  			__vb2_buf_userptr_put(vb);
  	}
  }
  
  /*
   * __vb2_queue_free() - free buffers at the end of the queue - video memory and
   * related information, if no buffers are left return the queue to an
   * uninitialized state. Might be called even if the queue has already been freed.
   */
  static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
  {
  	unsigned int buffer;
  
  	/*
  	 * Sanity check: when preparing a buffer the queue lock is released for
  	 * a short while (see __buf_prepare for the details), which would allow
  	 * a race with a reqbufs which can call this function. Removing the
  	 * buffers from underneath __buf_prepare is obviously a bad idea, so we
  	 * check if any of the buffers is in the state PREPARING, and if so we
  	 * just return -EAGAIN.
  	 */
  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
  	     ++buffer) {
  		if (q->bufs[buffer] == NULL)
  			continue;
  		if (q->bufs[buffer]->state == VB2_BUF_STATE_PREPARING) {
  			dprintk(1, "preparing buffers, cannot free\n");
  			return -EAGAIN;
  		}
  	}
  
  	/* Call driver-provided cleanup function for each buffer, if provided */
  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
  	     ++buffer) {
  		struct vb2_buffer *vb = q->bufs[buffer];
  
  		if (vb && vb->planes[0].mem_priv)
  			call_void_vb_qop(vb, buf_cleanup, vb);
  	}
  
  	/* Release video buffer memory */
  	__vb2_free_mem(q, buffers);
  
  #ifdef CONFIG_VIDEO_ADV_DEBUG
  	/*
  	 * Check that all the calls were balances during the life-time of this
  	 * queue. If not (or if the debug level is 1 or up), then dump the
  	 * counters to the kernel log.
  	 */
  	if (q->num_buffers) {
  		bool unbalanced = q->cnt_start_streaming != q->cnt_stop_streaming ||
  				  q->cnt_wait_prepare != q->cnt_wait_finish;
  
  		if (unbalanced || debug) {
  			pr_info("counters for queue %p:%s\n", q,
  				unbalanced ? " UNBALANCED!" : "");
  			pr_info("     setup: %u start_streaming: %u stop_streaming: %u\n",
  				q->cnt_queue_setup, q->cnt_start_streaming,
  				q->cnt_stop_streaming);
  			pr_info("     wait_prepare: %u wait_finish: %u\n",
  				q->cnt_wait_prepare, q->cnt_wait_finish);
  		}
  		q->cnt_queue_setup = 0;
  		q->cnt_wait_prepare = 0;
  		q->cnt_wait_finish = 0;
  		q->cnt_start_streaming = 0;
  		q->cnt_stop_streaming = 0;
  	}
  	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
  		struct vb2_buffer *vb = q->bufs[buffer];
  		bool unbalanced = vb->cnt_mem_alloc != vb->cnt_mem_put ||
  				  vb->cnt_mem_prepare != vb->cnt_mem_finish ||
  				  vb->cnt_mem_get_userptr != vb->cnt_mem_put_userptr ||
  				  vb->cnt_mem_attach_dmabuf != vb->cnt_mem_detach_dmabuf ||
  				  vb->cnt_mem_map_dmabuf != vb->cnt_mem_unmap_dmabuf ||
  				  vb->cnt_buf_queue != vb->cnt_buf_done ||
  				  vb->cnt_buf_prepare != vb->cnt_buf_finish ||
  				  vb->cnt_buf_init != vb->cnt_buf_cleanup;
  
  		if (unbalanced || debug) {
  			pr_info("   counters for queue %p, buffer %d:%s\n",
  				q, buffer, unbalanced ? " UNBALANCED!" : "");
  			pr_info("     buf_init: %u buf_cleanup: %u buf_prepare: %u buf_finish: %u\n",
  				vb->cnt_buf_init, vb->cnt_buf_cleanup,
  				vb->cnt_buf_prepare, vb->cnt_buf_finish);
  			pr_info("     buf_out_validate: %u buf_queue: %u buf_done: %u buf_request_complete: %u\n",
  				vb->cnt_buf_out_validate, vb->cnt_buf_queue,
  				vb->cnt_buf_done, vb->cnt_buf_request_complete);
  			pr_info("     alloc: %u put: %u prepare: %u finish: %u mmap: %u\n",
  				vb->cnt_mem_alloc, vb->cnt_mem_put,
  				vb->cnt_mem_prepare, vb->cnt_mem_finish,
  				vb->cnt_mem_mmap);
  			pr_info("     get_userptr: %u put_userptr: %u\n",
  				vb->cnt_mem_get_userptr, vb->cnt_mem_put_userptr);
  			pr_info("     attach_dmabuf: %u detach_dmabuf: %u map_dmabuf: %u unmap_dmabuf: %u\n",
  				vb->cnt_mem_attach_dmabuf, vb->cnt_mem_detach_dmabuf,
  				vb->cnt_mem_map_dmabuf, vb->cnt_mem_unmap_dmabuf);
  			pr_info("     get_dmabuf: %u num_users: %u vaddr: %u cookie: %u\n",
  				vb->cnt_mem_get_dmabuf,
  				vb->cnt_mem_num_users,
  				vb->cnt_mem_vaddr,
  				vb->cnt_mem_cookie);
  		}
  	}
  #endif
  
  	/* Free videobuf buffers */
  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
  	     ++buffer) {
  		kfree(q->bufs[buffer]);
  		q->bufs[buffer] = NULL;
  	}
  
  	q->num_buffers -= buffers;
  	if (!q->num_buffers) {
  		q->memory = VB2_MEMORY_UNKNOWN;
  		INIT_LIST_HEAD(&q->queued_list);
  	}
  	return 0;
  }
  
  bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb)
  {
  	unsigned int plane;
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		void *mem_priv = vb->planes[plane].mem_priv;
  		/*
  		 * If num_users() has not been provided, call_memop
  		 * will return 0, apparently nobody cares about this
  		 * case anyway. If num_users() returns more than 1,
  		 * we are not the only user of the plane's memory.
  		 */
  		if (mem_priv && call_memop(vb, num_users, mem_priv) > 1)
  			return true;
  	}
  	return false;
  }
  EXPORT_SYMBOL(vb2_buffer_in_use);
  
  /*
   * __buffers_in_use() - return true if any buffers on the queue are in use and
   * the queue cannot be freed (by the means of REQBUFS(0)) call
   */
  static bool __buffers_in_use(struct vb2_queue *q)
  {
  	unsigned int buffer;
  	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
  		if (vb2_buffer_in_use(q, q->bufs[buffer]))
  			return true;
  	}
  	return false;
  }
  
  void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb)
  {
  	call_void_bufop(q, fill_user_buffer, q->bufs[index], pb);
  }
  EXPORT_SYMBOL_GPL(vb2_core_querybuf);
  
  /*
   * __verify_userptr_ops() - verify that all memory operations required for
   * USERPTR queue type have been provided
   */
  static int __verify_userptr_ops(struct vb2_queue *q)
  {
  	if (!(q->io_modes & VB2_USERPTR) || !q->mem_ops->get_userptr ||
  	    !q->mem_ops->put_userptr)
  		return -EINVAL;
  
  	return 0;
  }
  
  /*
   * __verify_mmap_ops() - verify that all memory operations required for
   * MMAP queue type have been provided
   */
  static int __verify_mmap_ops(struct vb2_queue *q)
  {
  	if (!(q->io_modes & VB2_MMAP) || !q->mem_ops->alloc ||
  	    !q->mem_ops->put || !q->mem_ops->mmap)
  		return -EINVAL;
  
  	return 0;
  }
  
  /*
   * __verify_dmabuf_ops() - verify that all memory operations required for
   * DMABUF queue type have been provided
   */
  static int __verify_dmabuf_ops(struct vb2_queue *q)
  {
  	if (!(q->io_modes & VB2_DMABUF) || !q->mem_ops->attach_dmabuf ||
  	    !q->mem_ops->detach_dmabuf  || !q->mem_ops->map_dmabuf ||
  	    !q->mem_ops->unmap_dmabuf)
  		return -EINVAL;
  
  	return 0;
  }
  
  int vb2_verify_memory_type(struct vb2_queue *q,
  		enum vb2_memory memory, unsigned int type)
  {
  	if (memory != VB2_MEMORY_MMAP && memory != VB2_MEMORY_USERPTR &&
  	    memory != VB2_MEMORY_DMABUF) {
  		dprintk(1, "unsupported memory type\n");
  		return -EINVAL;
  	}
  
  	if (type != q->type) {
  		dprintk(1, "requested type is incorrect\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * Make sure all the required memory ops for given memory type
  	 * are available.
  	 */
  	if (memory == VB2_MEMORY_MMAP && __verify_mmap_ops(q)) {
  		dprintk(1, "MMAP for current setup unsupported\n");
  		return -EINVAL;
  	}
  
  	if (memory == VB2_MEMORY_USERPTR && __verify_userptr_ops(q)) {
  		dprintk(1, "USERPTR for current setup unsupported\n");
  		return -EINVAL;
  	}
  
  	if (memory == VB2_MEMORY_DMABUF && __verify_dmabuf_ops(q)) {
  		dprintk(1, "DMABUF for current setup unsupported\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * Place the busy tests at the end: -EBUSY can be ignored when
  	 * create_bufs is called with count == 0, but count == 0 should still
  	 * do the memory and type validation.
  	 */
  	if (vb2_fileio_is_active(q)) {
  		dprintk(1, "file io in progress\n");
  		return -EBUSY;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(vb2_verify_memory_type);
  
  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
  		unsigned int *count)
  {
  	unsigned int num_buffers, allocated_buffers, num_planes = 0;
  	unsigned plane_sizes[VB2_MAX_PLANES] = { };
  	unsigned int i;
  	int ret;
  
  	if (q->streaming) {
  		dprintk(1, "streaming active\n");
  		return -EBUSY;
  	}
  
  	if (q->waiting_in_dqbuf && *count) {
  		dprintk(1, "another dup()ped fd is waiting for a buffer\n");
  		return -EBUSY;
  	}
  
  	if (*count == 0 || q->num_buffers != 0 ||
  	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
  		/*
  		 * We already have buffers allocated, so first check if they
  		 * are not in use and can be freed.
  		 */
  		mutex_lock(&q->mmap_lock);
  		if (debug && q->memory == VB2_MEMORY_MMAP &&
  		    __buffers_in_use(q))
  			dprintk(1, "memory in use, orphaning buffers\n");
  
  		/*
  		 * Call queue_cancel to clean up any buffers in the
  		 * QUEUED state which is possible if buffers were prepared or
  		 * queued without ever calling STREAMON.
  		 */
  		__vb2_queue_cancel(q);
  		ret = __vb2_queue_free(q, q->num_buffers);
  		mutex_unlock(&q->mmap_lock);
  		if (ret)
  			return ret;
  
  		/*
  		 * In case of REQBUFS(0) return immediately without calling
  		 * driver's queue_setup() callback and allocating resources.
  		 */
  		if (*count == 0)
  			return 0;
  	}
  
  	/*
  	 * Make sure the requested values and current defaults are sane.
  	 */
  	WARN_ON(q->min_buffers_needed > VB2_MAX_FRAME);
  	num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
  	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
  	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
  	q->memory = memory;
  
  	/*
  	 * Ask the driver how many buffers and planes per buffer it requires.
  	 * Driver also sets the size and allocator context for each plane.
  	 */
  	ret = call_qop(q, queue_setup, q, &num_buffers, &num_planes,
  		       plane_sizes, q->alloc_devs);
  	if (ret)
  		return ret;
  
  	/* Check that driver has set sane values */
  	if (WARN_ON(!num_planes))
  		return -EINVAL;
  
  	for (i = 0; i < num_planes; i++)
  		if (WARN_ON(!plane_sizes[i]))
  			return -EINVAL;
  
  	/* Finally, allocate buffers and video memory */
  	allocated_buffers =
  		__vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
  	if (allocated_buffers == 0) {
  		dprintk(1, "memory allocation failed\n");
  		return -ENOMEM;
  	}
  
  	/*
  	 * There is no point in continuing if we can't allocate the minimum
  	 * number of buffers needed by this vb2_queue.
  	 */
  	if (allocated_buffers < q->min_buffers_needed)
  		ret = -ENOMEM;
  
  	/*
  	 * Check if driver can handle the allocated number of buffers.
  	 */
  	if (!ret && allocated_buffers < num_buffers) {
  		num_buffers = allocated_buffers;
  		/*
  		 * num_planes is set by the previous queue_setup(), but since it
  		 * signals to queue_setup() whether it is called from create_bufs()
  		 * vs reqbufs() we zero it here to signal that queue_setup() is
  		 * called for the reqbufs() case.
  		 */
  		num_planes = 0;
  
  		ret = call_qop(q, queue_setup, q, &num_buffers,
  			       &num_planes, plane_sizes, q->alloc_devs);
  
  		if (!ret && allocated_buffers < num_buffers)
  			ret = -ENOMEM;
  
  		/*
  		 * Either the driver has accepted a smaller number of buffers,
  		 * or .queue_setup() returned an error
  		 */
  	}
  
  	mutex_lock(&q->mmap_lock);
  	q->num_buffers = allocated_buffers;
  
  	if (ret < 0) {
  		/*
  		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
  		 * from q->num_buffers.
  		 */
  		__vb2_queue_free(q, allocated_buffers);
  		mutex_unlock(&q->mmap_lock);
  		return ret;
  	}
  	mutex_unlock(&q->mmap_lock);
  
  	/*
  	 * Return the number of successfully allocated buffers
  	 * to the userspace.
  	 */
  	*count = allocated_buffers;
  	q->waiting_for_buffers = !q->is_output;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_reqbufs);
  
  int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
  		unsigned int *count, unsigned requested_planes,
  		const unsigned requested_sizes[])
  {
  	unsigned int num_planes = 0, num_buffers, allocated_buffers;
  	unsigned plane_sizes[VB2_MAX_PLANES] = { };
  	int ret;
  
  	if (q->num_buffers == VB2_MAX_FRAME) {
  		dprintk(1, "maximum number of buffers already allocated\n");
  		return -ENOBUFS;
  	}
  
  	if (!q->num_buffers) {
  		if (q->waiting_in_dqbuf && *count) {
  			dprintk(1, "another dup()ped fd is waiting for a buffer\n");
  			return -EBUSY;
  		}
  		memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
  		q->memory = memory;
  		q->waiting_for_buffers = !q->is_output;
  	} else if (q->memory != memory) {
  		dprintk(1, "memory model mismatch\n");
  		return -EINVAL;
  	}
  
  	num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);
  
  	if (requested_planes && requested_sizes) {
  		num_planes = requested_planes;
  		memcpy(plane_sizes, requested_sizes, sizeof(plane_sizes));
  	}
  
  	/*
  	 * Ask the driver, whether the requested number of buffers, planes per
  	 * buffer and their sizes are acceptable
  	 */
  	ret = call_qop(q, queue_setup, q, &num_buffers,
  		       &num_planes, plane_sizes, q->alloc_devs);
  	if (ret)
  		return ret;
  
  	/* Finally, allocate buffers and video memory */
  	allocated_buffers = __vb2_queue_alloc(q, memory, num_buffers,
  				num_planes, plane_sizes);
  	if (allocated_buffers == 0) {
  		dprintk(1, "memory allocation failed\n");
  		return -ENOMEM;
  	}
  
  	/*
  	 * Check if driver can handle the so far allocated number of buffers.
  	 */
  	if (allocated_buffers < num_buffers) {
  		num_buffers = allocated_buffers;
  
  		/*
  		 * q->num_buffers contains the total number of buffers, that the
  		 * queue driver has set up
  		 */
  		ret = call_qop(q, queue_setup, q, &num_buffers,
  			       &num_planes, plane_sizes, q->alloc_devs);
  
  		if (!ret && allocated_buffers < num_buffers)
  			ret = -ENOMEM;
  
  		/*
  		 * Either the driver has accepted a smaller number of buffers,
  		 * or .queue_setup() returned an error
  		 */
  	}
  
  	mutex_lock(&q->mmap_lock);
  	q->num_buffers += allocated_buffers;
  
  	if (ret < 0) {
  		/*
  		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
  		 * from q->num_buffers.
  		 */
  		__vb2_queue_free(q, allocated_buffers);
  		mutex_unlock(&q->mmap_lock);
  		return -ENOMEM;
  	}
  	mutex_unlock(&q->mmap_lock);
  
  	/*
  	 * Return the number of successfully allocated buffers
  	 * to the userspace.
  	 */
  	*count = allocated_buffers;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_create_bufs);
  
  void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no)
  {
  	if (plane_no >= vb->num_planes || !vb->planes[plane_no].mem_priv)
  		return NULL;
  
  	return call_ptr_memop(vb, vaddr, vb->planes[plane_no].mem_priv);
  
  }
  EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
  
  void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no)
  {
  	if (plane_no >= vb->num_planes || !vb->planes[plane_no].mem_priv)
  		return NULL;
  
  	return call_ptr_memop(vb, cookie, vb->planes[plane_no].mem_priv);
  }
  EXPORT_SYMBOL_GPL(vb2_plane_cookie);
  
  void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  	unsigned long flags;
  	unsigned int plane;
  
  	if (WARN_ON(vb->state != VB2_BUF_STATE_ACTIVE))
  		return;
  
  	if (WARN_ON(state != VB2_BUF_STATE_DONE &&
  		    state != VB2_BUF_STATE_ERROR &&
  		    state != VB2_BUF_STATE_QUEUED))
  		state = VB2_BUF_STATE_ERROR;
  
  #ifdef CONFIG_VIDEO_ADV_DEBUG
  	/*
  	 * Although this is not a callback, it still does have to balance
  	 * with the buf_queue op. So update this counter manually.
  	 */
  	vb->cnt_buf_done++;
  #endif
  	dprintk(4, "done processing on buffer %d, state: %d\n",
  			vb->index, state);
  
  	if (state != VB2_BUF_STATE_QUEUED) {
  		/* sync buffers */
  		for (plane = 0; plane < vb->num_planes; ++plane)
  			call_void_memop(vb, finish, vb->planes[plane].mem_priv);
  		vb->synced = 0;
  	}
  
  	spin_lock_irqsave(&q->done_lock, flags);
  	if (state == VB2_BUF_STATE_QUEUED) {
  		vb->state = VB2_BUF_STATE_QUEUED;
  	} else {
  		/* Add the buffer to the done buffers list */
  		list_add_tail(&vb->done_entry, &q->done_list);
  		vb->state = state;
  	}
  	atomic_dec(&q->owned_by_drv_count);
  
  	if (state != VB2_BUF_STATE_QUEUED && vb->req_obj.req) {
  		media_request_object_unbind(&vb->req_obj);
  		media_request_object_put(&vb->req_obj);
  	}
  
  	spin_unlock_irqrestore(&q->done_lock, flags);
  
  	trace_vb2_buf_done(q, vb);
  
  	switch (state) {
  	case VB2_BUF_STATE_QUEUED:
  		return;
  	default:
  		/* Inform any processes that may be waiting for buffers */
  		wake_up(&q->done_wq);
  		break;
  	}
  }
  EXPORT_SYMBOL_GPL(vb2_buffer_done);
  
  void vb2_discard_done(struct vb2_queue *q)
  {
  	struct vb2_buffer *vb;
  	unsigned long flags;
  
  	spin_lock_irqsave(&q->done_lock, flags);
  	list_for_each_entry(vb, &q->done_list, done_entry)
  		vb->state = VB2_BUF_STATE_ERROR;
  	spin_unlock_irqrestore(&q->done_lock, flags);
  }
  EXPORT_SYMBOL_GPL(vb2_discard_done);
  
  /*
   * __prepare_mmap() - prepare an MMAP buffer
   */
  static int __prepare_mmap(struct vb2_buffer *vb)
  {
  	int ret = 0;
  
  	ret = call_bufop(vb->vb2_queue, fill_vb2_buffer,
  			 vb, vb->planes);
  	return ret ? ret : call_vb_qop(vb, buf_prepare, vb);
  }
  
  /*
   * __prepare_userptr() - prepare a USERPTR buffer
   */
  static int __prepare_userptr(struct vb2_buffer *vb)
  {
  	struct vb2_plane planes[VB2_MAX_PLANES];
  	struct vb2_queue *q = vb->vb2_queue;
  	void *mem_priv;
  	unsigned int plane;
  	int ret = 0;
  	bool reacquired = vb->planes[0].mem_priv == NULL;
  
  	memset(planes, 0, sizeof(planes[0]) * vb->num_planes);
  	/* Copy relevant information provided by the userspace */
  	ret = call_bufop(vb->vb2_queue, fill_vb2_buffer,
  			 vb, planes);
  	if (ret)
  		return ret;
  
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		/* Skip the plane if already verified */
  		if (vb->planes[plane].m.userptr &&
  			vb->planes[plane].m.userptr == planes[plane].m.userptr
  			&& vb->planes[plane].length == planes[plane].length)
  			continue;
  
  		dprintk(3, "userspace address for plane %d changed, reacquiring memory\n",
  			plane);
  
  		/* Check if the provided plane buffer is large enough */
  		if (planes[plane].length < vb->planes[plane].min_length) {
  			dprintk(1, "provided buffer size %u is less than setup size %u for plane %d\n",
  						planes[plane].length,
  						vb->planes[plane].min_length,
  						plane);
  			ret = -EINVAL;
  			goto err;
  		}
  
  		/* Release previously acquired memory if present */
  		if (vb->planes[plane].mem_priv) {
  			if (!reacquired) {
  				reacquired = true;
  				vb->copied_timestamp = 0;
  				call_void_vb_qop(vb, buf_cleanup, vb);
  			}
  			call_void_memop(vb, put_userptr, vb->planes[plane].mem_priv);
  		}
  
  		vb->planes[plane].mem_priv = NULL;
  		vb->planes[plane].bytesused = 0;
  		vb->planes[plane].length = 0;
  		vb->planes[plane].m.userptr = 0;
  		vb->planes[plane].data_offset = 0;
  
  		/* Acquire each plane's memory */
  		mem_priv = call_ptr_memop(vb, get_userptr,
  				q->alloc_devs[plane] ? : q->dev,
  				planes[plane].m.userptr,
  				planes[plane].length, q->dma_dir);
  		if (IS_ERR(mem_priv)) {
  			dprintk(1, "failed acquiring userspace memory for plane %d\n",
  				plane);
  			ret = PTR_ERR(mem_priv);
  			goto err;
  		}
  		vb->planes[plane].mem_priv = mem_priv;
  	}
  
  	/*
  	 * Now that everything is in order, copy relevant information
  	 * provided by userspace.
  	 */
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		vb->planes[plane].bytesused = planes[plane].bytesused;
  		vb->planes[plane].length = planes[plane].length;
  		vb->planes[plane].m.userptr = planes[plane].m.userptr;
  		vb->planes[plane].data_offset = planes[plane].data_offset;
  	}
  
  	if (reacquired) {
  		/*
  		 * One or more planes changed, so we must call buf_init to do
  		 * the driver-specific initialization on the newly acquired
  		 * buffer, if provided.
  		 */
  		ret = call_vb_qop(vb, buf_init, vb);
  		if (ret) {
  			dprintk(1, "buffer initialization failed\n");
  			goto err;
  		}
  	}
  
  	ret = call_vb_qop(vb, buf_prepare, vb);
  	if (ret) {
  		dprintk(1, "buffer preparation failed\n");
  		call_void_vb_qop(vb, buf_cleanup, vb);
  		goto err;
  	}
  
  	return 0;
  err:
  	/* In case of errors, release planes that were already acquired */
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		if (vb->planes[plane].mem_priv)
  			call_void_memop(vb, put_userptr,
  				vb->planes[plane].mem_priv);
  		vb->planes[plane].mem_priv = NULL;
  		vb->planes[plane].m.userptr = 0;
  		vb->planes[plane].length = 0;
  	}
  
  	return ret;
  }
  
  /*
   * __prepare_dmabuf() - prepare a DMABUF buffer
   */
  static int __prepare_dmabuf(struct vb2_buffer *vb)
  {
  	struct vb2_plane planes[VB2_MAX_PLANES];
  	struct vb2_queue *q = vb->vb2_queue;
  	void *mem_priv;
  	unsigned int plane;
  	int ret = 0;
  	bool reacquired = vb->planes[0].mem_priv == NULL;
  
  	memset(planes, 0, sizeof(planes[0]) * vb->num_planes);
  	/* Copy relevant information provided by the userspace */
  	ret = call_bufop(vb->vb2_queue, fill_vb2_buffer,
  			 vb, planes);
  	if (ret)
  		return ret;
  
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		struct dma_buf *dbuf = dma_buf_get(planes[plane].m.fd);
  
  		if (IS_ERR_OR_NULL(dbuf)) {
  			dprintk(1, "invalid dmabuf fd for plane %d\n",
  				plane);
  			ret = -EINVAL;
  			goto err;
  		}
  
  		/* use DMABUF size if length is not provided */
  		if (planes[plane].length == 0)
  			planes[plane].length = dbuf->size;
  
  		if (planes[plane].length < vb->planes[plane].min_length) {
  			dprintk(1, "invalid dmabuf length %u for plane %d, minimum length %u\n",
  				planes[plane].length, plane,
  				vb->planes[plane].min_length);
  			dma_buf_put(dbuf);
  			ret = -EINVAL;
  			goto err;
  		}
  
  		/* Skip the plane if already verified */
  		if (dbuf == vb->planes[plane].dbuf &&
  			vb->planes[plane].length == planes[plane].length) {
  			dma_buf_put(dbuf);
  			continue;
  		}
  
  		dprintk(3, "buffer for plane %d changed\n", plane);
  
  		if (!reacquired) {
  			reacquired = true;
  			vb->copied_timestamp = 0;
  			call_void_vb_qop(vb, buf_cleanup, vb);
  		}
  
  		/* Release previously acquired memory if present */
  		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
  		vb->planes[plane].bytesused = 0;
  		vb->planes[plane].length = 0;
  		vb->planes[plane].m.fd = 0;
  		vb->planes[plane].data_offset = 0;
  
  		/* Acquire each plane's memory */
  		mem_priv = call_ptr_memop(vb, attach_dmabuf,
  				q->alloc_devs[plane] ? : q->dev,
  				dbuf, planes[plane].length, q->dma_dir);
  		if (IS_ERR(mem_priv)) {
  			dprintk(1, "failed to attach dmabuf\n");
  			ret = PTR_ERR(mem_priv);
  			dma_buf_put(dbuf);
  			goto err;
  		}
  
  		vb->planes[plane].dbuf = dbuf;
  		vb->planes[plane].mem_priv = mem_priv;
  	}
  
  	/*
  	 * This pins the buffer(s) with dma_buf_map_attachment()). It's done
  	 * here instead just before the DMA, while queueing the buffer(s) so
  	 * userspace knows sooner rather than later if the dma-buf map fails.
  	 */
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		if (vb->planes[plane].dbuf_mapped)
  			continue;
  
  		ret = call_memop(vb, map_dmabuf, vb->planes[plane].mem_priv);
  		if (ret) {
  			dprintk(1, "failed to map dmabuf for plane %d\n",
  				plane);
  			goto err;
  		}
  		vb->planes[plane].dbuf_mapped = 1;
  	}
  
  	/*
  	 * Now that everything is in order, copy relevant information
  	 * provided by userspace.
  	 */
  	for (plane = 0; plane < vb->num_planes; ++plane) {
  		vb->planes[plane].bytesused = planes[plane].bytesused;
  		vb->planes[plane].length = planes[plane].length;
  		vb->planes[plane].m.fd = planes[plane].m.fd;
  		vb->planes[plane].data_offset = planes[plane].data_offset;
  	}
  
  	if (reacquired) {
  		/*
  		 * Call driver-specific initialization on the newly acquired buffer,
  		 * if provided.
  		 */
  		ret = call_vb_qop(vb, buf_init, vb);
  		if (ret) {
  			dprintk(1, "buffer initialization failed\n");
  			goto err;
  		}
  	}
  
  	ret = call_vb_qop(vb, buf_prepare, vb);
  	if (ret) {
  		dprintk(1, "buffer preparation failed\n");
  		call_void_vb_qop(vb, buf_cleanup, vb);
  		goto err;
  	}
  
  	return 0;
  err:
  	/* In case of errors, release planes that were already acquired */
  	__vb2_buf_dmabuf_put(vb);
  
  	return ret;
  }
  
  /*
   * __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
   */
  static void __enqueue_in_driver(struct vb2_buffer *vb)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  
  	vb->state = VB2_BUF_STATE_ACTIVE;
  	atomic_inc(&q->owned_by_drv_count);
  
  	trace_vb2_buf_queue(q, vb);
  
  	call_void_vb_qop(vb, buf_queue, vb);
  }
  
  static int __buf_prepare(struct vb2_buffer *vb)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  	enum vb2_buffer_state orig_state = vb->state;
  	unsigned int plane;
  	int ret;
  
  	if (q->error) {
  		dprintk(1, "fatal error occurred on queue\n");
  		return -EIO;
  	}
  
  	if (vb->prepared)
  		return 0;
  	WARN_ON(vb->synced);
  
  	if (q->is_output) {
  		ret = call_vb_qop(vb, buf_out_validate, vb);
  		if (ret) {
  			dprintk(1, "buffer validation failed\n");
  			return ret;
  		}
  	}
  
  	vb->state = VB2_BUF_STATE_PREPARING;
  
  	switch (q->memory) {
  	case VB2_MEMORY_MMAP:
  		ret = __prepare_mmap(vb);
  		break;
  	case VB2_MEMORY_USERPTR:
  		ret = __prepare_userptr(vb);
  		break;
  	case VB2_MEMORY_DMABUF:
  		ret = __prepare_dmabuf(vb);
  		break;
  	default:
  		WARN(1, "Invalid queue type\n");
  		ret = -EINVAL;
  		break;
  	}
  
  	if (ret) {
  		dprintk(1, "buffer preparation failed: %d\n", ret);
  		vb->state = orig_state;
  		return ret;
  	}
  
  	/* sync buffers */
  	for (plane = 0; plane < vb->num_planes; ++plane)
  		call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
  
  	vb->synced = 1;
  	vb->prepared = 1;
  	vb->state = orig_state;
  
  	return 0;
  }
  
  static int vb2_req_prepare(struct media_request_object *obj)
  {
  	struct vb2_buffer *vb = container_of(obj, struct vb2_buffer, req_obj);
  	int ret;
  
  	if (WARN_ON(vb->state != VB2_BUF_STATE_IN_REQUEST))
  		return -EINVAL;
  
  	mutex_lock(vb->vb2_queue->lock);
  	ret = __buf_prepare(vb);
  	mutex_unlock(vb->vb2_queue->lock);
  	return ret;
  }
  
  static void __vb2_dqbuf(struct vb2_buffer *vb);
  
  static void vb2_req_unprepare(struct media_request_object *obj)
  {
  	struct vb2_buffer *vb = container_of(obj, struct vb2_buffer, req_obj);
  
  	mutex_lock(vb->vb2_queue->lock);
  	__vb2_dqbuf(vb);
  	vb->state = VB2_BUF_STATE_IN_REQUEST;
  	mutex_unlock(vb->vb2_queue->lock);
  	WARN_ON(!vb->req_obj.req);
  }
  
  int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
  		  struct media_request *req);
  
  static void vb2_req_queue(struct media_request_object *obj)
  {
  	struct vb2_buffer *vb = container_of(obj, struct vb2_buffer, req_obj);
  
  	mutex_lock(vb->vb2_queue->lock);
  	vb2_core_qbuf(vb->vb2_queue, vb->index, NULL, NULL);
  	mutex_unlock(vb->vb2_queue->lock);
  }
  
  static void vb2_req_unbind(struct media_request_object *obj)
  {
  	struct vb2_buffer *vb = container_of(obj, struct vb2_buffer, req_obj);
  
  	if (vb->state == VB2_BUF_STATE_IN_REQUEST)
  		call_void_bufop(vb->vb2_queue, init_buffer, vb);
  }
  
  static void vb2_req_release(struct media_request_object *obj)
  {
  	struct vb2_buffer *vb = container_of(obj, struct vb2_buffer, req_obj);
  
  	if (vb->state == VB2_BUF_STATE_IN_REQUEST) {
  		vb->state = VB2_BUF_STATE_DEQUEUED;
  		if (vb->request)
  			media_request_put(vb->request);
  		vb->request = NULL;
  	}
  }
  
  static const struct media_request_object_ops vb2_core_req_ops = {
  	.prepare = vb2_req_prepare,
  	.unprepare = vb2_req_unprepare,
  	.queue = vb2_req_queue,
  	.unbind = vb2_req_unbind,
  	.release = vb2_req_release,
  };
  
  bool vb2_request_object_is_buffer(struct media_request_object *obj)
  {
  	return obj->ops == &vb2_core_req_ops;
  }
  EXPORT_SYMBOL_GPL(vb2_request_object_is_buffer);
  
  unsigned int vb2_request_buffer_cnt(struct media_request *req)
  {
  	struct media_request_object *obj;
  	unsigned long flags;
  	unsigned int buffer_cnt = 0;
  
  	spin_lock_irqsave(&req->lock, flags);
  	list_for_each_entry(obj, &req->objects, list)
  		if (vb2_request_object_is_buffer(obj))
  			buffer_cnt++;
  	spin_unlock_irqrestore(&req->lock, flags);
  
  	return buffer_cnt;
  }
  EXPORT_SYMBOL_GPL(vb2_request_buffer_cnt);
  
  int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
  {
  	struct vb2_buffer *vb;
  	int ret;
  
  	vb = q->bufs[index];
  	if (vb->state != VB2_BUF_STATE_DEQUEUED) {
  		dprintk(1, "invalid buffer state %d\n",
  			vb->state);
  		return -EINVAL;
  	}
  	if (vb->prepared) {
  		dprintk(1, "buffer already prepared\n");
  		return -EINVAL;
  	}
  
  	ret = __buf_prepare(vb);
  	if (ret)
  		return ret;
  
  	/* Fill buffer information for the userspace */
  	call_void_bufop(q, fill_user_buffer, vb, pb);
  
  	dprintk(2, "prepare of buffer %d succeeded\n", vb->index);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
  
  /*
   * vb2_start_streaming() - Attempt to start streaming.
   * @q:		videobuf2 queue
   *
   * Attempt to start streaming. When this function is called there must be
   * at least q->min_buffers_needed buffers queued up (i.e. the minimum
   * number of buffers required for the DMA engine to function). If the
   * @start_streaming op fails it is supposed to return all the driver-owned
   * buffers back to vb2 in state QUEUED. Check if that happened and if
   * not warn and reclaim them forcefully.
   */
  static int vb2_start_streaming(struct vb2_queue *q)
  {
  	struct vb2_buffer *vb;
  	int ret;
  
  	/*
  	 * If any buffers were queued before streamon,
  	 * we can now pass them to driver for processing.
  	 */
  	list_for_each_entry(vb, &q->queued_list, queued_entry)
  		__enqueue_in_driver(vb);
  
  	/* Tell the driver to start streaming */
  	q->start_streaming_called = 1;
  	ret = call_qop(q, start_streaming, q,
  		       atomic_read(&q->owned_by_drv_count));
  	if (!ret)
  		return 0;
  
  	q->start_streaming_called = 0;
  
  	dprintk(1, "driver refused to start streaming\n");
  	/*
  	 * If you see this warning, then the driver isn't cleaning up properly
  	 * after a failed start_streaming(). See the start_streaming()
  	 * documentation in videobuf2-core.h for more information how buffers
  	 * should be returned to vb2 in start_streaming().
  	 */
  	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
  		unsigned i;
  
  		/*
  		 * Forcefully reclaim buffers if the driver did not
  		 * correctly return them to vb2.
  		 */
  		for (i = 0; i < q->num_buffers; ++i) {
  			vb = q->bufs[i];
  			if (vb->state == VB2_BUF_STATE_ACTIVE)
  				vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED);
  		}
  		/* Must be zero now */
  		WARN_ON(atomic_read(&q->owned_by_drv_count));
  	}
  	/*
  	 * If done_list is not empty, then start_streaming() didn't call
  	 * vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED) but STATE_ERROR or
  	 * STATE_DONE.
  	 */
  	WARN_ON(!list_empty(&q->done_list));
  	return ret;
  }
  
  int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
  		  struct media_request *req)
  {
  	struct vb2_buffer *vb;
  	int ret;
  
  	if (q->error) {
  		dprintk(1, "fatal error occurred on queue\n");
  		return -EIO;
  	}
  
  	vb = q->bufs[index];
  
  	if (!req && vb->state != VB2_BUF_STATE_IN_REQUEST &&
  	    q->requires_requests) {
  		dprintk(1, "qbuf requires a request\n");
  		return -EBADR;
  	}
  
  	if ((req && q->uses_qbuf) ||
  	    (!req && vb->state != VB2_BUF_STATE_IN_REQUEST &&
  	     q->uses_requests)) {
  		dprintk(1, "queue in wrong mode (qbuf vs requests)\n");
  		return -EBUSY;
  	}
  
  	if (req) {
  		int ret;
  
  		q->uses_requests = 1;
  		if (vb->state != VB2_BUF_STATE_DEQUEUED) {
  			dprintk(1, "buffer %d not in dequeued state\n",
  				vb->index);
  			return -EINVAL;
  		}
  
  		if (q->is_output && !vb->prepared) {
  			ret = call_vb_qop(vb, buf_out_validate, vb);
  			if (ret) {
  				dprintk(1, "buffer validation failed\n");
  				return ret;
  			}
  		}
  
  		media_request_object_init(&vb->req_obj);
  
  		/* Make sure the request is in a safe state for updating. */
  		ret = media_request_lock_for_update(req);
  		if (ret)
  			return ret;
  		ret = media_request_object_bind(req, &vb2_core_req_ops,
  						q, true, &vb->req_obj);
  		media_request_unlock_for_update(req);
  		if (ret)
  			return ret;
  
  		vb->state = VB2_BUF_STATE_IN_REQUEST;
  
  		/*
  		 * Increment the refcount and store the request.
  		 * The request refcount is decremented again when the
  		 * buffer is dequeued. This is to prevent vb2_buffer_done()
  		 * from freeing the request from interrupt context, which can
  		 * happen if the application closed the request fd after
  		 * queueing the request.
  		 */
  		media_request_get(req);
  		vb->request = req;
  
  		/* Fill buffer information for the userspace */
  		if (pb) {
  			call_void_bufop(q, copy_timestamp, vb, pb);
  			call_void_bufop(q, fill_user_buffer, vb, pb);
  		}
  
  		dprintk(2, "qbuf of buffer %d succeeded\n", vb->index);
  		return 0;
  	}
  
  	if (vb->state != VB2_BUF_STATE_IN_REQUEST)
  		q->uses_qbuf = 1;
  
  	switch (vb->state) {
  	case VB2_BUF_STATE_DEQUEUED:
  	case VB2_BUF_STATE_IN_REQUEST:
  		if (!vb->prepared) {
  			ret = __buf_prepare(vb);
  			if (ret)
  				return ret;
  		}
  		break;
  	case VB2_BUF_STATE_PREPARING:
  		dprintk(1, "buffer still being prepared\n");
  		return -EINVAL;
  	default:
  		dprintk(1, "invalid buffer state %d\n", vb->state);
  		return -EINVAL;
  	}
  
  	/*
  	 * Add to the queued buffers list, a buffer will stay on it until
  	 * dequeued in dqbuf.
  	 */
  	list_add_tail(&vb->queued_entry, &q->queued_list);
  	q->queued_count++;
  	q->waiting_for_buffers = false;
  	vb->state = VB2_BUF_STATE_QUEUED;
  
  	if (pb)
  		call_void_bufop(q, copy_timestamp, vb, pb);
  
  	trace_vb2_qbuf(q, vb);
  
  	/*
  	 * If already streaming, give the buffer to driver for processing.
  	 * If not, the buffer will be given to driver on next streamon.
  	 */
  	if (q->start_streaming_called)
  		__enqueue_in_driver(vb);
  
  	/* Fill buffer information for the userspace */
  	if (pb)
  		call_void_bufop(q, fill_user_buffer, vb, pb);
  
  	/*
  	 * If streamon has been called, and we haven't yet called
  	 * start_streaming() since not enough buffers were queued, and
  	 * we now have reached the minimum number of queued buffers,
  	 * then we can finally call start_streaming().
  	 */
  	if (q->streaming && !q->start_streaming_called &&
  	    q->queued_count >= q->min_buffers_needed) {
  		ret = vb2_start_streaming(q);
  		if (ret)
  			return ret;
  	}
  
  	dprintk(2, "qbuf of buffer %d succeeded\n", vb->index);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_qbuf);
  
  /*
   * __vb2_wait_for_done_vb() - wait for a buffer to become available
   * for dequeuing
   *
   * Will sleep if required for nonblocking == false.
   */
  static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
  {
  	/*
  	 * All operations on vb_done_list are performed under done_lock
  	 * spinlock protection. However, buffers may be removed from
  	 * it and returned to userspace only while holding both driver's
  	 * lock and the done_lock spinlock. Thus we can be sure that as
  	 * long as we hold the driver's lock, the list will remain not
  	 * empty if list_empty() check succeeds.
  	 */
  
  	for (;;) {
  		int ret;
  
  		if (q->waiting_in_dqbuf) {
  			dprintk(1, "another dup()ped fd is waiting for a buffer\n");
  			return -EBUSY;
  		}
  
  		if (!q->streaming) {
  			dprintk(1, "streaming off, will not wait for buffers\n");
  			return -EINVAL;
  		}
  
  		if (q->error) {
  			dprintk(1, "Queue in error state, will not wait for buffers\n");
  			return -EIO;
  		}
  
  		if (q->last_buffer_dequeued) {
  			dprintk(3, "last buffer dequeued already, will not wait for buffers\n");
  			return -EPIPE;
  		}
  
  		if (!list_empty(&q->done_list)) {
  			/*
  			 * Found a buffer that we were waiting for.
  			 */
  			break;
  		}
  
  		if (nonblocking) {
  			dprintk(3, "nonblocking and no buffers to dequeue, will not wait\n");
  			return -EAGAIN;
  		}
  
  		q->waiting_in_dqbuf = 1;
  		/*
  		 * We are streaming and blocking, wait for another buffer to
  		 * become ready or for streamoff. Driver's lock is released to
  		 * allow streamoff or qbuf to be called while waiting.
  		 */
  		call_void_qop(q, wait_prepare, q);
  
  		/*
  		 * All locks have been released, it is safe to sleep now.
  		 */
  		dprintk(3, "will sleep waiting for buffers\n");
  		ret = wait_event_interruptible(q->done_wq,
  				!list_empty(&q->done_list) || !q->streaming ||
  				q->error);
  
  		/*
  		 * We need to reevaluate both conditions again after reacquiring
  		 * the locks or return an error if one occurred.
  		 */
  		call_void_qop(q, wait_finish, q);
  		q->waiting_in_dqbuf = 0;
  		if (ret) {
  			dprintk(1, "sleep was interrupted\n");
  			return ret;
  		}
  	}
  	return 0;
  }
  
  /*
   * __vb2_get_done_vb() - get a buffer ready for dequeuing
   *
   * Will sleep if required for nonblocking == false.
   */
  static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
  			     void *pb, int nonblocking)
  {
  	unsigned long flags;
  	int ret = 0;
  
  	/*
  	 * Wait for at least one buffer to become available on the done_list.
  	 */
  	ret = __vb2_wait_for_done_vb(q, nonblocking);
  	if (ret)
  		return ret;
  
  	/*
  	 * Driver's lock has been held since we last verified that done_list
  	 * is not empty, so no need for another list_empty(done_list) check.
  	 */
  	spin_lock_irqsave(&q->done_lock, flags);
  	*vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
  	/*
  	 * Only remove the buffer from done_list if all planes can be
  	 * handled. Some cases such as V4L2 file I/O and DVB have pb
  	 * == NULL; skip the check then as there's nothing to verify.
  	 */
  	if (pb)
  		ret = call_bufop(q, verify_planes_array, *vb, pb);
  	if (!ret)
  		list_del(&(*vb)->done_entry);
  	spin_unlock_irqrestore(&q->done_lock, flags);
  
  	return ret;
  }
  
  int vb2_wait_for_all_buffers(struct vb2_queue *q)
  {
  	if (!q->streaming) {
  		dprintk(1, "streaming off, will not wait for buffers\n");
  		return -EINVAL;
  	}
  
  	if (q->start_streaming_called)
  		wait_event(q->done_wq, !atomic_read(&q->owned_by_drv_count));
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_wait_for_all_buffers);
  
  /*
   * __vb2_dqbuf() - bring back the buffer to the DEQUEUED state
   */
  static void __vb2_dqbuf(struct vb2_buffer *vb)
  {
  	struct vb2_queue *q = vb->vb2_queue;
  
  	/* nothing to do if the buffer is already dequeued */
  	if (vb->state == VB2_BUF_STATE_DEQUEUED)
  		return;
  
  	vb->state = VB2_BUF_STATE_DEQUEUED;
  
  	call_void_bufop(q, init_buffer, vb);
  }
  
  int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb,
  		   bool nonblocking)
  {
  	struct vb2_buffer *vb = NULL;
  	int ret;
  
  	ret = __vb2_get_done_vb(q, &vb, pb, nonblocking);
  	if (ret < 0)
  		return ret;
  
  	switch (vb->state) {
  	case VB2_BUF_STATE_DONE:
  		dprintk(3, "returning done buffer\n");
  		break;
  	case VB2_BUF_STATE_ERROR:
  		dprintk(3, "returning done buffer with errors\n");
  		break;
  	default:
  		dprintk(1, "invalid buffer state\n");
  		return -EINVAL;
  	}
  
  	call_void_vb_qop(vb, buf_finish, vb);
  	vb->prepared = 0;
  
  	if (pindex)
  		*pindex = vb->index;
  
  	/* Fill buffer information for the userspace */
  	if (pb)
  		call_void_bufop(q, fill_user_buffer, vb, pb);
  
  	/* Remove from videobuf queue */
  	list_del(&vb->queued_entry);
  	q->queued_count--;
  
  	trace_vb2_dqbuf(q, vb);
  
  	/* go back to dequeued state */
  	__vb2_dqbuf(vb);
  
  	if (WARN_ON(vb->req_obj.req)) {
  		media_request_object_unbind(&vb->req_obj);
  		media_request_object_put(&vb->req_obj);
  	}
  	if (vb->request)
  		media_request_put(vb->request);
  	vb->request = NULL;
  
  	dprintk(2, "dqbuf of buffer %d, with state %d\n",
  			vb->index, vb->state);
  
  	return 0;
  
  }
  EXPORT_SYMBOL_GPL(vb2_core_dqbuf);
  
  /*
   * __vb2_queue_cancel() - cancel and stop (pause) streaming
   *
   * Removes all queued buffers from driver's queue and all buffers queued by
   * userspace from videobuf's queue. Returns to state after reqbufs.
   */
  static void __vb2_queue_cancel(struct vb2_queue *q)
  {
  	unsigned int i;
  
  	/*
  	 * Tell driver to stop all transactions and release all queued
  	 * buffers.
  	 */
  	if (q->start_streaming_called)
  		call_void_qop(q, stop_streaming, q);
  
  	/*
  	 * If you see this warning, then the driver isn't cleaning up properly
  	 * in stop_streaming(). See the stop_streaming() documentation in
  	 * videobuf2-core.h for more information how buffers should be returned
  	 * to vb2 in stop_streaming().
  	 */
  	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
  		for (i = 0; i < q->num_buffers; ++i)
  			if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE) {
  				pr_warn("driver bug: stop_streaming operation is leaving buf %p in active state\n",
  					q->bufs[i]);
  				vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
  			}
  		/* Must be zero now */
  		WARN_ON(atomic_read(&q->owned_by_drv_count));
  	}
  
  	q->streaming = 0;
  	q->start_streaming_called = 0;
  	q->queued_count = 0;
  	q->error = 0;
  	q->uses_requests = 0;
  	q->uses_qbuf = 0;
  
  	/*
  	 * Remove all buffers from videobuf's list...
  	 */
  	INIT_LIST_HEAD(&q->queued_list);
  	/*
  	 * ...and done list; userspace will not receive any buffers it
  	 * has not already dequeued before initiating cancel.
  	 */
  	INIT_LIST_HEAD(&q->done_list);
  	atomic_set(&q->owned_by_drv_count, 0);
  	wake_up_all(&q->done_wq);
  
  	/*
  	 * Reinitialize all buffers for next use.
  	 * Make sure to call buf_finish for any queued buffers. Normally
  	 * that's done in dqbuf, but that's not going to happen when we
  	 * cancel the whole queue. Note: this code belongs here, not in
  	 * __vb2_dqbuf() since in vb2_core_dqbuf() there is a critical
  	 * call to __fill_user_buffer() after buf_finish(). That order can't
  	 * be changed, so we can't move the buf_finish() to __vb2_dqbuf().
  	 */
  	for (i = 0; i < q->num_buffers; ++i) {
  		struct vb2_buffer *vb = q->bufs[i];
  		struct media_request *req = vb->req_obj.req;
  
  		/*
  		 * If a request is associated with this buffer, then
  		 * call buf_request_cancel() to give the driver to complete()
  		 * related request objects. Otherwise those objects would
  		 * never complete.
  		 */
  		if (req) {
  			enum media_request_state state;
  			unsigned long flags;
  
  			spin_lock_irqsave(&req->lock, flags);
  			state = req->state;
  			spin_unlock_irqrestore(&req->lock, flags);
  
  			if (state == MEDIA_REQUEST_STATE_QUEUED)
  				call_void_vb_qop(vb, buf_request_complete, vb);
  		}
  
  		if (vb->synced) {
  			unsigned int plane;
  
  			for (plane = 0; plane < vb->num_planes; ++plane)
  				call_void_memop(vb, finish,
  						vb->planes[plane].mem_priv);
  			vb->synced = 0;
  		}
  
  		if (vb->prepared) {
  			call_void_vb_qop(vb, buf_finish, vb);
  			vb->prepared = 0;
  		}
  		__vb2_dqbuf(vb);
  
  		if (vb->req_obj.req) {
  			media_request_object_unbind(&vb->req_obj);
  			media_request_object_put(&vb->req_obj);
  		}
  		if (vb->request)
  			media_request_put(vb->request);
  		vb->request = NULL;
  		vb->copied_timestamp = 0;
  	}
  }
  
  int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
  {
  	int ret;
  
  	if (type != q->type) {
  		dprintk(1, "invalid stream type\n");
  		return -EINVAL;
  	}
  
  	if (q->streaming) {
  		dprintk(3, "already streaming\n");
  		return 0;
  	}
  
  	if (!q->num_buffers) {
  		dprintk(1, "no buffers have been allocated\n");
  		return -EINVAL;
  	}
  
  	if (q->num_buffers < q->min_buffers_needed) {
  		dprintk(1, "need at least %u allocated buffers\n",
  				q->min_buffers_needed);
  		return -EINVAL;
  	}
  
  	/*
  	 * Tell driver to start streaming provided sufficient buffers
  	 * are available.
  	 */
  	if (q->queued_count >= q->min_buffers_needed) {
  		ret = v4l_vb2q_enable_media_source(q);
  		if (ret)
  			return ret;
  		ret = vb2_start_streaming(q);
  		if (ret)
  			return ret;
  	}
  
  	q->streaming = 1;
  
  	dprintk(3, "successful\n");
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_streamon);
  
  void vb2_queue_error(struct vb2_queue *q)
  {
  	q->error = 1;
  
  	wake_up_all(&q->done_wq);
  }
  EXPORT_SYMBOL_GPL(vb2_queue_error);
  
  int vb2_core_streamoff(struct vb2_queue *q, unsigned int type)
  {
  	if (type != q->type) {
  		dprintk(1, "invalid stream type\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * Cancel will pause streaming and remove all buffers from the driver
  	 * and videobuf, effectively returning control over them to userspace.
  	 *
  	 * Note that we do this even if q->streaming == 0: if you prepare or
  	 * queue buffers, and then call streamoff without ever having called
  	 * streamon, you would still expect those buffers to be returned to
  	 * their normal dequeued state.
  	 */
  	__vb2_queue_cancel(q);
  	q->waiting_for_buffers = !q->is_output;
  	q->last_buffer_dequeued = false;
  
  	dprintk(3, "successful\n");
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_streamoff);
  
  /*
   * __find_plane_by_offset() - find plane associated with the given offset off
   */
  static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off,
  			unsigned int *_buffer, unsigned int *_plane)
  {
  	struct vb2_buffer *vb;
  	unsigned int buffer, plane;
  
  	/*
  	 * Go over all buffers and their planes, comparing the given offset
  	 * with an offset assigned to each plane. If a match is found,
  	 * return its buffer and plane numbers.
  	 */
  	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
  		vb = q->bufs[buffer];
  
  		for (plane = 0; plane < vb->num_planes; ++plane) {
  			if (vb->planes[plane].m.offset == off) {
  				*_buffer = buffer;
  				*_plane = plane;
  				return 0;
  			}
  		}
  	}
  
  	return -EINVAL;
  }
  
  int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
  		unsigned int index, unsigned int plane, unsigned int flags)
  {
  	struct vb2_buffer *vb = NULL;
  	struct vb2_plane *vb_plane;
  	int ret;
  	struct dma_buf *dbuf;
  
  	if (q->memory != VB2_MEMORY_MMAP) {
  		dprintk(1, "queue is not currently set up for mmap\n");
  		return -EINVAL;
  	}
  
  	if (!q->mem_ops->get_dmabuf) {
  		dprintk(1, "queue does not support DMA buffer exporting\n");
  		return -EINVAL;
  	}
  
  	if (flags & ~(O_CLOEXEC | O_ACCMODE)) {
  		dprintk(1, "queue does support only O_CLOEXEC and access mode flags\n");
  		return -EINVAL;
  	}
  
  	if (type != q->type) {
  		dprintk(1, "invalid buffer type\n");
  		return -EINVAL;
  	}
  
  	if (index >= q->num_buffers) {
  		dprintk(1, "buffer index out of range\n");
  		return -EINVAL;
  	}
  
  	vb = q->bufs[index];
  
  	if (plane >= vb->num_planes) {
  		dprintk(1, "buffer plane out of range\n");
  		return -EINVAL;
  	}
  
  	if (vb2_fileio_is_active(q)) {
  		dprintk(1, "expbuf: file io in progress\n");
  		return -EBUSY;
  	}
  
  	vb_plane = &vb->planes[plane];
  
  	dbuf = call_ptr_memop(vb, get_dmabuf, vb_plane->mem_priv,
  				flags & O_ACCMODE);
  	if (IS_ERR_OR_NULL(dbuf)) {
  		dprintk(1, "failed to export buffer %d, plane %d\n",
  			index, plane);
  		return -EINVAL;
  	}
  
  	ret = dma_buf_fd(dbuf, flags & ~O_ACCMODE);
  	if (ret < 0) {
  		dprintk(3, "buffer %d, plane %d failed to export (%d)\n",
  			index, plane, ret);
  		dma_buf_put(dbuf);
  		return ret;
  	}
  
  	dprintk(3, "buffer %d, plane %d exported as %d descriptor\n",
  		index, plane, ret);
  	*fd = ret;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_expbuf);
  
  int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
  {
  	unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
  	struct vb2_buffer *vb;
  	unsigned int buffer = 0, plane = 0;
  	int ret;
  	unsigned long length;
  
  	if (q->memory != VB2_MEMORY_MMAP) {
  		dprintk(1, "queue is not currently set up for mmap\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * Check memory area access mode.
  	 */
  	if (!(vma->vm_flags & VM_SHARED)) {
  		dprintk(1, "invalid vma flags, VM_SHARED needed\n");
  		return -EINVAL;
  	}
  	if (q->is_output) {
  		if (!(vma->vm_flags & VM_WRITE)) {
  			dprintk(1, "invalid vma flags, VM_WRITE needed\n");
  			return -EINVAL;
  		}
  	} else {
  		if (!(vma->vm_flags & VM_READ)) {
  			dprintk(1, "invalid vma flags, VM_READ needed\n");
  			return -EINVAL;
  		}
  	}
  
  	mutex_lock(&q->mmap_lock);
  
  	if (vb2_fileio_is_active(q)) {
  		dprintk(1, "mmap: file io in progress\n");
  		ret = -EBUSY;
  		goto unlock;
  	}
  
  	/*
  	 * Find the plane corresponding to the offset passed by userspace.
  	 */
  	ret = __find_plane_by_offset(q, off, &buffer, &plane);
  	if (ret)
  		goto unlock;
  
  	vb = q->bufs[buffer];
  
  	/*
  	 * MMAP requires page_aligned buffers.
  	 * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
  	 * so, we need to do the same here.
  	 */
  	length = PAGE_ALIGN(vb->planes[plane].length);
  	if (length < (vma->vm_end - vma->vm_start)) {
  		dprintk(1,
  			"MMAP invalid, as it would overflow buffer length\n");
  		ret = -EINVAL;
  		goto unlock;
  	}
  
  	/*
  	 * vm_pgoff is treated in V4L2 API as a 'cookie' to select a buffer,
  	 * not as a in-buffer offset. We always want to mmap a whole buffer
  	 * from its beginning.
  	 */
  	vma->vm_pgoff = 0;
  
  	ret = call_memop(vb, mmap, vb->planes[plane].mem_priv, vma);
  
  unlock:
  	mutex_unlock(&q->mmap_lock);
  	if (ret)
  		return ret;
  
  	dprintk(3, "buffer %d, plane %d successfully mapped\n", buffer, plane);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_mmap);
  
  #ifndef CONFIG_MMU
  unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
  				    unsigned long addr,
  				    unsigned long len,
  				    unsigned long pgoff,
  				    unsigned long flags)
  {
  	unsigned long off = pgoff << PAGE_SHIFT;
  	struct vb2_buffer *vb;
  	unsigned int buffer, plane;
  	void *vaddr;
  	int ret;
  
  	if (q->memory != VB2_MEMORY_MMAP) {
  		dprintk(1, "queue is not currently set up for mmap\n");
  		return -EINVAL;
  	}
  
  	/*
  	 * Find the plane corresponding to the offset passed by userspace.
  	 */
  	ret = __find_plane_by_offset(q, off, &buffer, &plane);
  	if (ret)
  		return ret;
  
  	vb = q->bufs[buffer];
  
  	vaddr = vb2_plane_vaddr(vb, plane);
  	return vaddr ? (unsigned long)vaddr : -EINVAL;
  }
  EXPORT_SYMBOL_GPL(vb2_get_unmapped_area);
  #endif
  
  int vb2_core_queue_init(struct vb2_queue *q)
  {
  	/*
  	 * Sanity check
  	 */
  	if (WARN_ON(!q)			  ||
  	    WARN_ON(!q->ops)		  ||
  	    WARN_ON(!q->mem_ops)	  ||
  	    WARN_ON(!q->type)		  ||
  	    WARN_ON(!q->io_modes)	  ||
  	    WARN_ON(!q->ops->queue_setup) ||
  	    WARN_ON(!q->ops->buf_queue))
  		return -EINVAL;
  
  	if (WARN_ON(q->requires_requests && !q->supports_requests))
  		return -EINVAL;
  
  	INIT_LIST_HEAD(&q->queued_list);
  	INIT_LIST_HEAD(&q->done_list);
  	spin_lock_init(&q->done_lock);
  	mutex_init(&q->mmap_lock);
  	init_waitqueue_head(&q->done_wq);
  
  	q->memory = VB2_MEMORY_UNKNOWN;
  
  	if (q->buf_struct_size == 0)
  		q->buf_struct_size = sizeof(struct vb2_buffer);
  
  	if (q->bidirectional)
  		q->dma_dir = DMA_BIDIRECTIONAL;
  	else
  		q->dma_dir = q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_queue_init);
  
  static int __vb2_init_fileio(struct vb2_queue *q, int read);
  static int __vb2_cleanup_fileio(struct vb2_queue *q);
  void vb2_core_queue_release(struct vb2_queue *q)
  {
  	__vb2_cleanup_fileio(q);
  	__vb2_queue_cancel(q);
  	mutex_lock(&q->mmap_lock);
  	__vb2_queue_free(q, q->num_buffers);
  	mutex_unlock(&q->mmap_lock);
  }
  EXPORT_SYMBOL_GPL(vb2_core_queue_release);
  
  __poll_t vb2_core_poll(struct vb2_queue *q, struct file *file,
  		poll_table *wait)
  {
  	__poll_t req_events = poll_requested_events(wait);
  	struct vb2_buffer *vb = NULL;
  	unsigned long flags;
  
  	if (!q->is_output && !(req_events & (EPOLLIN | EPOLLRDNORM)))
  		return 0;
  	if (q->is_output && !(req_events & (EPOLLOUT | EPOLLWRNORM)))
  		return 0;
  
  	poll_wait(file, &q->done_wq, wait);
  
  	/*
  	 * Start file I/O emulator only if streaming API has not been used yet.
  	 */
  	if (q->num_buffers == 0 && !vb2_fileio_is_active(q)) {
  		if (!q->is_output && (q->io_modes & VB2_READ) &&
  				(req_events & (EPOLLIN | EPOLLRDNORM))) {
  			if (__vb2_init_fileio(q, 1))
  				return EPOLLERR;
  		}
  		if (q->is_output && (q->io_modes & VB2_WRITE) &&
  				(req_events & (EPOLLOUT | EPOLLWRNORM))) {
  			if (__vb2_init_fileio(q, 0))
  				return EPOLLERR;
  			/*
  			 * Write to OUTPUT queue can be done immediately.
  			 */
  			return EPOLLOUT | EPOLLWRNORM;
  		}
  	}
  
  	/*
  	 * There is nothing to wait for if the queue isn't streaming, or if the
  	 * error flag is set.
  	 */
  	if (!vb2_is_streaming(q) || q->error)
  		return EPOLLERR;
  
  	/*
  	 * If this quirk is set and QBUF hasn't been called yet then
  	 * return EPOLLERR as well. This only affects capture queues, output
  	 * queues will always initialize waiting_for_buffers to false.
  	 * This quirk is set by V4L2 for backwards compatibility reasons.
  	 */
  	if (q->quirk_poll_must_check_waiting_for_buffers &&
  	    q->waiting_for_buffers && (req_events & (EPOLLIN | EPOLLRDNORM)))
  		return EPOLLERR;
  
  	/*
  	 * For output streams you can call write() as long as there are fewer
  	 * buffers queued than there are buffers available.
  	 */
  	if (q->is_output && q->fileio && q->queued_count < q->num_buffers)
  		return EPOLLOUT | EPOLLWRNORM;
  
  	if (list_empty(&q->done_list)) {
  		/*
  		 * If the last buffer was dequeued from a capture queue,
  		 * return immediately. DQBUF will return -EPIPE.
  		 */
  		if (q->last_buffer_dequeued)
  			return EPOLLIN | EPOLLRDNORM;
  	}
  
  	/*
  	 * Take first buffer available for dequeuing.
  	 */
  	spin_lock_irqsave(&q->done_lock, flags);
  	if (!list_empty(&q->done_list))
  		vb = list_first_entry(&q->done_list, struct vb2_buffer,
  					done_entry);
  	spin_unlock_irqrestore(&q->done_lock, flags);
  
  	if (vb && (vb->state == VB2_BUF_STATE_DONE
  			|| vb->state == VB2_BUF_STATE_ERROR)) {
  		return (q->is_output) ?
  				EPOLLOUT | EPOLLWRNORM :
  				EPOLLIN | EPOLLRDNORM;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(vb2_core_poll);
  
  /*
   * struct vb2_fileio_buf - buffer context used by file io emulator
   *
   * vb2 provides a compatibility layer and emulator of file io (read and
   * write) calls on top of streaming API. This structure is used for
   * tracking context related to the buffers.
   */
  struct vb2_fileio_buf {
  	void *vaddr;
  	unsigned int size;
  	unsigned int pos;
  	unsigned int queued:1;
  };
  
  /*
   * struct vb2_fileio_data - queue context used by file io emulator
   *
   * @cur_index:	the index of the buffer currently being read from or
   *		written to. If equal to q->num_buffers then a new buffer
   *		must be dequeued.
   * @initial_index: in the read() case all buffers are queued up immediately
   *		in __vb2_init_fileio() and __vb2_perform_fileio() just cycles
   *		buffers. However, in the write() case no buffers are initially
   *		queued, instead whenever a buffer is full it is queued up by
   *		__vb2_perform_fileio(). Only once all available buffers have
   *		been queued up will __vb2_perform_fileio() start to dequeue
   *		buffers. This means that initially __vb2_perform_fileio()
   *		needs to know what buffer index to use when it is queuing up
   *		the buffers for the first time. That initial index is stored
   *		in this field. Once it is equal to q->num_buffers all
   *		available buffers have been queued and __vb2_perform_fileio()
   *		should start the normal dequeue/queue cycle.
   *
   * vb2 provides a compatibility layer and emulator of file io (read and
   * write) calls on top of streaming API. For proper operation it required
   * this structure to save the driver state between each call of the read
   * or write function.
   */
  struct vb2_fileio_data {
  	unsigned int count;
  	unsigned int type;
  	unsigned int memory;
  	struct vb2_fileio_buf bufs[VB2_MAX_FRAME];
  	unsigned int cur_index;
  	unsigned int initial_index;
  	unsigned int q_count;
  	unsigned int dq_count;
  	unsigned read_once:1;
  	unsigned write_immediately:1;
  };
  
  /*
   * __vb2_init_fileio() - initialize file io emulator
   * @q:		videobuf2 queue
   * @read:	mode selector (1 means read, 0 means write)
   */
  static int __vb2_init_fileio(struct vb2_queue *q, int read)
  {
  	struct vb2_fileio_data *fileio;
  	int i, ret;
  	unsigned int count = 0;
  
  	/*
  	 * Sanity check
  	 */
  	if (WARN_ON((read && !(q->io_modes & VB2_READ)) ||
  		    (!read && !(q->io_modes & VB2_WRITE))))
  		return -EINVAL;
  
  	/*
  	 * Check if device supports mapping buffers to kernel virtual space.
  	 */
  	if (!q->mem_ops->vaddr)
  		return -EBUSY;
  
  	/*
  	 * Check if streaming api has not been already activated.
  	 */
  	if (q->streaming || q->num_buffers > 0)
  		return -EBUSY;
  
  	/*
  	 * Start with count 1, driver can increase it in queue_setup()
  	 */
  	count = 1;
  
  	dprintk(3, "setting up file io: mode %s, count %d, read_once %d, write_immediately %d\n",
  		(read) ? "read" : "write", count, q->fileio_read_once,
  		q->fileio_write_immediately);
  
  	fileio = kzalloc(sizeof(*fileio), GFP_KERNEL);
  	if (fileio == NULL)
  		return -ENOMEM;
  
  	fileio->read_once = q->fileio_read_once;
  	fileio->write_immediately = q->fileio_write_immediately;
  
  	/*
  	 * Request buffers and use MMAP type to force driver
  	 * to allocate buffers by itself.
  	 */
  	fileio->count = count;
  	fileio->memory = VB2_MEMORY_MMAP;
  	fileio->type = q->type;
  	q->fileio = fileio;
  	ret = vb2_core_reqbufs(q, fileio->memory, &fileio->count);
  	if (ret)
  		goto err_kfree;
  
  	/*
  	 * Check if plane_count is correct
  	 * (multiplane buffers are not supported).
  	 */
  	if (q->bufs[0]->num_planes != 1) {
  		ret = -EBUSY;
  		goto err_reqbufs;
  	}
  
  	/*
  	 * Get kernel address of each buffer.
  	 */
  	for (i = 0; i < q->num_buffers; i++) {
  		fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
  		if (fileio->bufs[i].vaddr == NULL) {
  			ret = -EINVAL;
  			goto err_reqbufs;
  		}
  		fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
  	}
  
  	/*
  	 * Read mode requires pre queuing of all buffers.
  	 */
  	if (read) {
  		/*
  		 * Queue all buffers.
  		 */
  		for (i = 0; i < q->num_buffers; i++) {
  			ret = vb2_core_qbuf(q, i, NULL, NULL);
  			if (ret)
  				goto err_reqbufs;
  			fileio->bufs[i].queued = 1;
  		}
  		/*
  		 * All buffers have been queued, so mark that by setting
  		 * initial_index to q->num_buffers
  		 */
  		fileio->initial_index = q->num_buffers;
  		fileio->cur_index = q->num_buffers;
  	}
  
  	/*
  	 * Start streaming.
  	 */
  	ret = vb2_core_streamon(q, q->type);
  	if (ret)
  		goto err_reqbufs;
  
  	return ret;
  
  err_reqbufs:
  	fileio->count = 0;
  	vb2_core_reqbufs(q, fileio->memory, &fileio->count);
  
  err_kfree:
  	q->fileio = NULL;
  	kfree(fileio);
  	return ret;
  }
  
  /*
   * __vb2_cleanup_fileio() - free resourced used by file io emulator
   * @q:		videobuf2 queue
   */
  static int __vb2_cleanup_fileio(struct vb2_queue *q)
  {
  	struct vb2_fileio_data *fileio = q->fileio;
  
  	if (fileio) {
  		vb2_core_streamoff(q, q->type);
  		q->fileio = NULL;
  		fileio->count = 0;
  		vb2_core_reqbufs(q, fileio->memory, &fileio->count);
  		kfree(fileio);
  		dprintk(3, "file io emulator closed\n");
  	}
  	return 0;
  }
  
  /*
   * __vb2_perform_fileio() - perform a single file io (read or write) operation
   * @q:		videobuf2 queue
   * @data:	pointed to target userspace buffer
   * @count:	number of bytes to read or write
   * @ppos:	file handle position tracking pointer
   * @nonblock:	mode selector (1 means blocking calls, 0 means nonblocking)
   * @read:	access mode selector (1 means read, 0 means write)
   */
  static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_t count,
  		loff_t *ppos, int nonblock, int read)
  {
  	struct vb2_fileio_data *fileio;
  	struct vb2_fileio_buf *buf;
  	bool is_multiplanar = q->is_multiplanar;
  	/*
  	 * When using write() to write data to an output video node the vb2 core
  	 * should copy timestamps if V4L2_BUF_FLAG_TIMESTAMP_COPY is set. Nobody
  	 * else is able to provide this information with the write() operation.
  	 */
  	bool copy_timestamp = !read && q->copy_timestamp;
  	unsigned index;
  	int ret;
  
  	dprintk(3, "mode %s, offset %ld, count %zd, %sblocking\n",
  		read ? "read" : "write", (long)*ppos, count,
  		nonblock ? "non" : "");
  
  	if (!data)
  		return -EINVAL;
  
  	if (q->waiting_in_dqbuf) {
  		dprintk(3, "another dup()ped fd is %s\n",
  			read ? "reading" : "writing");
  		return -EBUSY;
  	}
  
  	/*
  	 * Initialize emulator on first call.
  	 */
  	if (!vb2_fileio_is_active(q)) {
  		ret = __vb2_init_fileio(q, read);
  		dprintk(3, "vb2_init_fileio result: %d\n", ret);
  		if (ret)
  			return ret;
  	}
  	fileio = q->fileio;
  
  	/*
  	 * Check if we need to dequeue the buffer.
  	 */
  	index = fileio->cur_index;
  	if (index >= q->num_buffers) {
  		struct vb2_buffer *b;
  
  		/*
  		 * Call vb2_dqbuf to get buffer back.
  		 */
  		ret = vb2_core_dqbuf(q, &index, NULL, nonblock);
  		dprintk(5, "vb2_dqbuf result: %d\n", ret);
  		if (ret)
  			return ret;
  		fileio->dq_count += 1;
  
  		fileio->cur_index = index;
  		buf = &fileio->bufs[index];
  		b = q->bufs[index];
  
  		/*
  		 * Get number of bytes filled by the driver
  		 */
  		buf->pos = 0;
  		buf->queued = 0;
  		buf->size = read ? vb2_get_plane_payload(q->bufs[index], 0)
  				 : vb2_plane_size(q->bufs[index], 0);
  		/* Compensate for data_offset on read in the multiplanar case. */
  		if (is_multiplanar && read &&
  				b->planes[0].data_offset < buf->size) {
  			buf->pos = b->planes[0].data_offset;
  			buf->size -= buf->pos;
  		}
  	} else {
  		buf = &fileio->bufs[index];
  	}
  
  	/*
  	 * Limit count on last few bytes of the buffer.
  	 */
  	if (buf->pos + count > buf->size) {
  		count = buf->size - buf->pos;
  		dprintk(5, "reducing read count: %zd\n", count);
  	}
  
  	/*
  	 * Transfer data to userspace.
  	 */
  	dprintk(3, "copying %zd bytes - buffer %d, offset %u\n",
  		count, index, buf->pos);
  	if (read)
  		ret = copy_to_user(data, buf->vaddr + buf->pos, count);
  	else
  		ret = copy_from_user(buf->vaddr + buf->pos, data, count);
  	if (ret) {
  		dprintk(3, "error copying data\n");
  		return -EFAULT;
  	}
  
  	/*
  	 * Update counters.
  	 */
  	buf->pos += count;
  	*ppos += count;
  
  	/*
  	 * Queue next buffer if required.
  	 */
  	if (buf->pos == buf->size || (!read && fileio->write_immediately)) {
  		struct vb2_buffer *b = q->bufs[index];
  
  		/*
  		 * Check if this is the last buffer to read.
  		 */
  		if (read && fileio->read_once && fileio->dq_count == 1) {
  			dprintk(3, "read limit reached\n");
  			return __vb2_cleanup_fileio(q);
  		}
  
  		/*
  		 * Call vb2_qbuf and give buffer to the driver.
  		 */
  		b->planes[0].bytesused = buf->pos;
  
  		if (copy_timestamp)
  			b->timestamp = ktime_get_ns();
  		ret = vb2_core_qbuf(q, index, NULL, NULL);
  		dprintk(5, "vb2_dbuf result: %d\n", ret);
  		if (ret)
  			return ret;
  
  		/*
  		 * Buffer has been queued, update the status
  		 */
  		buf->pos = 0;
  		buf->queued = 1;
  		buf->size = vb2_plane_size(q->bufs[index], 0);
  		fileio->q_count += 1;
  		/*
  		 * If we are queuing up buffers for the first time, then
  		 * increase initial_index by one.
  		 */
  		if (fileio->initial_index < q->num_buffers)
  			fileio->initial_index++;
  		/*
  		 * The next buffer to use is either a buffer that's going to be
  		 * queued for the first time (initial_index < q->num_buffers)
  		 * or it is equal to q->num_buffers, meaning that the next
  		 * time we need to dequeue a buffer since we've now queued up
  		 * all the 'first time' buffers.
  		 */
  		fileio->cur_index = fileio->initial_index;
  	}
  
  	/*
  	 * Return proper number of bytes processed.
  	 */
  	if (ret == 0)
  		ret = count;
  	return ret;
  }
  
  size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
  		loff_t *ppos, int nonblocking)
  {
  	return __vb2_perform_fileio(q, data, count, ppos, nonblocking, 1);
  }
  EXPORT_SYMBOL_GPL(vb2_read);
  
  size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
  		loff_t *ppos, int nonblocking)
  {
  	return __vb2_perform_fileio(q, (char __user *) data, count,
  							ppos, nonblocking, 0);
  }
  EXPORT_SYMBOL_GPL(vb2_write);
  
  struct vb2_threadio_data {
  	struct task_struct *thread;
  	vb2_thread_fnc fnc;
  	void *priv;
  	bool stop;
  };
  
  static int vb2_thread(void *data)
  {
  	struct vb2_queue *q = data;
  	struct vb2_threadio_data *threadio = q->threadio;
  	bool copy_timestamp = false;
  	unsigned prequeue = 0;
  	unsigned index = 0;
  	int ret = 0;
  
  	if (q->is_output) {
  		prequeue = q->num_buffers;
  		copy_timestamp = q->copy_timestamp;
  	}
  
  	set_freezable();
  
  	for (;;) {
  		struct vb2_buffer *vb;
  
  		/*
  		 * Call vb2_dqbuf to get buffer back.
  		 */
  		if (prequeue) {
  			vb = q->bufs[index++];
  			prequeue--;
  		} else {
  			call_void_qop(q, wait_finish, q);
  			if (!threadio->stop)
  				ret = vb2_core_dqbuf(q, &index, NULL, 0);
  			call_void_qop(q, wait_prepare, q);
  			dprintk(5, "file io: vb2_dqbuf result: %d\n", ret);
  			if (!ret)
  				vb = q->bufs[index];
  		}
  		if (ret || threadio->stop)
  			break;
  		try_to_freeze();
  
  		if (vb->state != VB2_BUF_STATE_ERROR)
  			if (threadio->fnc(vb, threadio->priv))
  				break;
  		call_void_qop(q, wait_finish, q);
  		if (copy_timestamp)
  			vb->timestamp = ktime_get_ns();
  		if (!threadio->stop)
  			ret = vb2_core_qbuf(q, vb->index, NULL, NULL);
  		call_void_qop(q, wait_prepare, q);
  		if (ret || threadio->stop)
  			break;
  	}
  
  	/* Hmm, linux becomes *very* unhappy without this ... */
  	while (!kthread_should_stop()) {
  		set_current_state(TASK_INTERRUPTIBLE);
  		schedule();
  	}
  	return 0;
  }
  
  /*
   * This function should not be used for anything else but the videobuf2-dvb
   * support. If you think you have another good use-case for this, then please
   * contact the linux-media mailinglist first.
   */
  int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
  		     const char *thread_name)
  {
  	struct vb2_threadio_data *threadio;
  	int ret = 0;
  
  	if (q->threadio)
  		return -EBUSY;
  	if (vb2_is_busy(q))
  		return -EBUSY;
  	if (WARN_ON(q->fileio))
  		return -EBUSY;
  
  	threadio = kzalloc(sizeof(*threadio), GFP_KERNEL);
  	if (threadio == NULL)
  		return -ENOMEM;
  	threadio->fnc = fnc;
  	threadio->priv = priv;
  
  	ret = __vb2_init_fileio(q, !q->is_output);
  	dprintk(3, "file io: vb2_init_fileio result: %d\n", ret);
  	if (ret)
  		goto nomem;
  	q->threadio = threadio;
  	threadio->thread = kthread_run(vb2_thread, q, "vb2-%s", thread_name);
  	if (IS_ERR(threadio->thread)) {
  		ret = PTR_ERR(threadio->thread);
  		threadio->thread = NULL;
  		goto nothread;
  	}
  	return 0;
  
  nothread:
  	__vb2_cleanup_fileio(q);
  nomem:
  	kfree(threadio);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(vb2_thread_start);
  
  int vb2_thread_stop(struct vb2_queue *q)
  {
  	struct vb2_threadio_data *threadio = q->threadio;
  	int err;
  
  	if (threadio == NULL)
  		return 0;
  	threadio->stop = true;
  	/* Wake up all pending sleeps in the thread */
  	vb2_queue_error(q);
  	err = kthread_stop(threadio->thread);
  	__vb2_cleanup_fileio(q);
  	threadio->thread = NULL;
  	kfree(threadio);
  	q->threadio = NULL;
  	return err;
  }
  EXPORT_SYMBOL_GPL(vb2_thread_stop);
  
  MODULE_DESCRIPTION("Media buffer core framework");
  MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>, Marek Szyprowski");
  MODULE_LICENSE("GPL");
  