OSCL-LXR linux-6.0.1/​drivers/​media/​common/​videobuf2/​videobuf2-core.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * 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(q, level, fmt, arg...)                  \
     do {                                \
         if (debug >= level)                 \
             pr_info("[%s] %s: " fmt, (q)->name, __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((vb)->vb2_queue, 2, "call_memop(%d, %s)%s\n",       \
         (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(op, vb, args...)                 \
 ({                                  \
     struct vb2_queue *_q = (vb)->vb2_queue;             \
     void *ptr;                          \
                                     \
     log_memop(vb, op);                      \
     ptr = _q->mem_ops->op ? _q->mem_ops->op(vb, 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(q, 2, "call_qop(%s)%s\n", #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((vb)->vb2_queue, 2, "call_vb_qop(%d, %s)%s\n",      \
         (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(op, vb, args...)                 \
     ((vb)->vb2_queue->mem_ops->op ?                 \
         (vb)->vb2_queue->mem_ops->op(vb, 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);
 
 static const char *vb2_state_name(enum vb2_buffer_state s)
 {
     static const char * const state_names[] = {
         [VB2_BUF_STATE_DEQUEUED] = "dequeued",
         [VB2_BUF_STATE_IN_REQUEST] = "in request",
         [VB2_BUF_STATE_PREPARING] = "preparing",
         [VB2_BUF_STATE_QUEUED] = "queued",
         [VB2_BUF_STATE_ACTIVE] = "active",
         [VB2_BUF_STATE_DONE] = "done",
         [VB2_BUF_STATE_ERROR] = "error",
     };
 
     if ((unsigned int)(s) < ARRAY_SIZE(state_names))
         return state_names[s];
     return "unknown";
 }
 
 /*
  * __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(alloc,
                       vb,
                       q->alloc_devs[plane] ? : q->dev,
                       size);
         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(vb->vb2_queue, 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]);
 }
 
 /*
  * __vb2_buf_mem_prepare() - call ->prepare() on buffer's private memory
  * to sync caches
  */
 static void __vb2_buf_mem_prepare(struct vb2_buffer *vb)
 {
     unsigned int plane;
 
     if (vb->synced)
         return;
 
     vb->synced = 1;
     for (plane = 0; plane < vb->num_planes; ++plane)
         call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
 }
 
 /*
  * __vb2_buf_mem_finish() - call ->finish on buffer's private memory
  * to sync caches
  */
 static void __vb2_buf_mem_finish(struct vb2_buffer *vb)
 {
     unsigned int plane;
 
     if (!vb->synced)
         return;
 
     vb->synced = 0;
     for (plane = 0; plane < vb->num_planes; ++plane)
         call_void_memop(vb, finish, vb->planes[plane].mem_priv);
 }
 
 /*
  * __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(q, 3, "buffer %d, plane %d offset 0x%08lx\n",
                 vb->index, plane, off);
 
         off += vb->planes[plane].length;
         off = PAGE_ALIGN(off);
     }
 }
 
 static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
 {
     /*
      * DMA exporter should take care of cache syncs, so we can avoid
      * explicit ->prepare()/->finish() syncs. For other ->memory types
      * we always need ->prepare() or/and ->finish() cache sync.
      */
     if (q->memory == VB2_MEMORY_DMABUF) {
         vb->skip_cache_sync_on_finish = 1;
         vb->skip_cache_sync_on_prepare = 1;
         return;
     }
 
     /*
      * ->finish() cache sync can be avoided when queue direction is
      * TO_DEVICE.
      */
     if (q->dma_dir == DMA_TO_DEVICE)
         vb->skip_cache_sync_on_finish = 1;
 }
 
 /*
  * __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(q, 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;
         init_buffer_cache_hints(q, vb);
         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(q, 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(q, 1, "buffer %d %p initialization failed\n",
                     buffer, vb);
                 __vb2_buf_mem_free(vb);
                 q->bufs[vb->index] = NULL;
                 kfree(vb);
                 break;
             }
         }
     }
 
     dprintk(q, 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(q, 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(q, 1, "unsupported memory type\n");
         return -EINVAL;
     }
 
     if (type != q->type) {
         dprintk(q, 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(q, 1, "MMAP for current setup unsupported\n");
         return -EINVAL;
     }
 
     if (memory == VB2_MEMORY_USERPTR && __verify_userptr_ops(q)) {
         dprintk(q, 1, "USERPTR for current setup unsupported\n");
         return -EINVAL;
     }
 
     if (memory == VB2_MEMORY_DMABUF && __verify_dmabuf_ops(q)) {
         dprintk(q, 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(q, 1, "file io in progress\n");
         return -EBUSY;
     }
     return 0;
 }
 EXPORT_SYMBOL(vb2_verify_memory_type);
 
 static void set_queue_coherency(struct vb2_queue *q, bool non_coherent_mem)
 {
     q->non_coherent_mem = 0;
 
     if (!vb2_queue_allows_cache_hints(q))
         return;
     q->non_coherent_mem = non_coherent_mem;
 }
 
 static bool verify_coherency_flags(struct vb2_queue *q, bool non_coherent_mem)
 {
     if (non_coherent_mem != q->non_coherent_mem) {
         dprintk(q, 1, "memory coherency model mismatch\n");
         return false;
     }
     return true;
 }
 
 int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
              unsigned int flags, unsigned int *count)
 {
     unsigned int num_buffers, allocated_buffers, num_planes = 0;
     unsigned plane_sizes[VB2_MAX_PLANES] = { };
     bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
     unsigned int i;
     int ret;
 
     if (q->streaming) {
         dprintk(q, 1, "streaming active\n");
         return -EBUSY;
     }
 
     if (q->waiting_in_dqbuf && *count) {
         dprintk(q, 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) ||
         !verify_coherency_flags(q, non_coherent_mem)) {
         /*
          * 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(q, 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;
     set_queue_coherency(q, non_coherent_mem);
 
     /*
      * 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(q, 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 flags, unsigned int *count,
              unsigned int requested_planes,
              const unsigned int requested_sizes[])
 {
     unsigned int num_planes = 0, num_buffers, allocated_buffers;
     unsigned plane_sizes[VB2_MAX_PLANES] = { };
     bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
     int ret;
 
     if (q->num_buffers == VB2_MAX_FRAME) {
         dprintk(q, 1, "maximum number of buffers already allocated\n");
         return -ENOBUFS;
     }
 
     if (!q->num_buffers) {
         if (q->waiting_in_dqbuf && *count) {
             dprintk(q, 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;
         set_queue_coherency(q, non_coherent_mem);
     } else {
         if (q->memory != memory) {
             dprintk(q, 1, "memory model mismatch\n");
             return -EINVAL;
         }
         if (!verify_coherency_flags(q, non_coherent_mem))
             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(q, 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(vaddr, vb, 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(cookie, vb, 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;
 
     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(q, 4, "done processing on buffer %d, state: %s\n",
         vb->index, vb2_state_name(state));
 
     if (state != VB2_BUF_STATE_QUEUED)
         __vb2_buf_mem_finish(vb);
 
     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(q, 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(q, 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(get_userptr,
                       vb,
                       q->alloc_devs[plane] ? : q->dev,
                       planes[plane].m.userptr,
                       planes[plane].length);
         if (IS_ERR(mem_priv)) {
             dprintk(q, 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(q, 1, "buffer initialization failed\n");
             goto err;
         }
     }
 
     ret = call_vb_qop(vb, buf_prepare, vb);
     if (ret) {
         dprintk(q, 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(q, 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(q, 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(q, 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(attach_dmabuf,
                       vb,
                       q->alloc_devs[plane] ? : q->dev,
                       dbuf,
                       planes[plane].length);
         if (IS_ERR(mem_priv)) {
             dprintk(q, 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(q, 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(q, 1, "buffer initialization failed\n");
             goto err;
         }
     }
 
     ret = call_vb_qop(vb, buf_prepare, vb);
     if (ret) {
         dprintk(q, 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;
     int ret;
 
     if (q->error) {
         dprintk(q, 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(q, 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(q, 1, "buffer preparation failed: %d\n", ret);
         vb->state = orig_state;
         return ret;
     }
 
     __vb2_buf_mem_prepare(vb);
     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);
     int err;
 
     mutex_lock(vb->vb2_queue->lock);
     /*
      * There is no method to propagate an error from vb2_core_qbuf(),
      * so if this returns a non-0 value, then WARN.
      *
      * The only exception is -EIO which is returned if q->error is
      * set. We just ignore that, and expect this will be caught the
      * next time vb2_req_prepare() is called.
      */
     err = vb2_core_qbuf(vb->vb2_queue, vb->index, NULL, NULL);
     WARN_ON_ONCE(err && err != -EIO);
     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(q, 1, "invalid buffer state %s\n",
             vb2_state_name(vb->state));
         return -EINVAL;
     }
     if (vb->prepared) {
         dprintk(q, 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(q, 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(q, 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;
     enum vb2_buffer_state orig_state;
     int ret;
 
     if (q->error) {
         dprintk(q, 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(q, 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(q, 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(q, 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(q, 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(q, 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(q, 1, "buffer still being prepared\n");
         return -EINVAL;
     default:
         dprintk(q, 1, "invalid buffer state %s\n",
             vb2_state_name(vb->state));
         return -EINVAL;
     }
 
     /*
      * Add to the queued buffers list, a buffer will stay on it until
      * dequeued in dqbuf.
      */
     orig_state = vb->state;
     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) {
             /*
              * Since vb2_core_qbuf will return with an error,
              * we should return it to state DEQUEUED since
              * the error indicates that the buffer wasn't queued.
              */
             list_del(&vb->queued_entry);
             q->queued_count--;
             vb->state = orig_state;
             return ret;
         }
     }
 
     dprintk(q, 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(q, 1, "another dup()ped fd is waiting for a buffer\n");
             return -EBUSY;
         }
 
         if (!q->streaming) {
             dprintk(q, 1, "streaming off, will not wait for buffers\n");
             return -EINVAL;
         }
 
         if (q->error) {
             dprintk(q, 1, "Queue in error state, will not wait for buffers\n");
             return -EIO;
         }
 
         if (q->last_buffer_dequeued) {
             dprintk(q, 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(q, 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(q, 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(q, 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(q, 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(q, 3, "returning done buffer\n");
         break;
     case VB2_BUF_STATE_ERROR:
         dprintk(q, 3, "returning done buffer with errors\n");
         break;
     default:
         dprintk(q, 1, "invalid buffer state %s\n",
             vb2_state_name(vb->state));
         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(q, 2, "dqbuf of buffer %d, state: %s\n",
         vb->index, vb2_state_name(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);
         }
 
         __vb2_buf_mem_finish(vb);
 
         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(q, 1, "invalid stream type\n");
         return -EINVAL;
     }
 
     if (q->streaming) {
         dprintk(q, 3, "already streaming\n");
         return 0;
     }
 
     if (!q->num_buffers) {
         dprintk(q, 1, "no buffers have been allocated\n");
         return -EINVAL;
     }
 
     if (q->num_buffers < q->min_buffers_needed) {
         dprintk(q, 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(q, 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(q, 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(q, 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(q, 1, "queue is not currently set up for mmap\n");
         return -EINVAL;
     }
 
     if (!q->mem_ops->get_dmabuf) {
         dprintk(q, 1, "queue does not support DMA buffer exporting\n");
         return -EINVAL;
     }
 
     if (flags & ~(O_CLOEXEC | O_ACCMODE)) {
         dprintk(q, 1, "queue does support only O_CLOEXEC and access mode flags\n");
         return -EINVAL;
     }
 
     if (type != q->type) {
         dprintk(q, 1, "invalid buffer type\n");
         return -EINVAL;
     }
 
     if (index >= q->num_buffers) {
         dprintk(q, 1, "buffer index out of range\n");
         return -EINVAL;
     }
 
     vb = q->bufs[index];
 
     if (plane >= vb->num_planes) {
         dprintk(q, 1, "buffer plane out of range\n");
         return -EINVAL;
     }
 
     if (vb2_fileio_is_active(q)) {
         dprintk(q, 1, "expbuf: file io in progress\n");
         return -EBUSY;
     }
 
     vb_plane = &vb->planes[plane];
 
     dbuf = call_ptr_memop(get_dmabuf,
                   vb,
                   vb_plane->mem_priv,
                   flags & O_ACCMODE);
     if (IS_ERR_OR_NULL(dbuf)) {
         dprintk(q, 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(q, 3, "buffer %d, plane %d failed to export (%d)\n",
             index, plane, ret);
         dma_buf_put(dbuf);
         return ret;
     }
 
     dprintk(q, 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(q, 1, "queue is not currently set up for mmap\n");
         return -EINVAL;
     }
 
     /*
      * Check memory area access mode.
      */
     if (!(vma->vm_flags & VM_SHARED)) {
         dprintk(q, 1, "invalid vma flags, VM_SHARED needed\n");
         return -EINVAL;
     }
     if (q->is_output) {
         if (!(vma->vm_flags & VM_WRITE)) {
             dprintk(q, 1, "invalid vma flags, VM_WRITE needed\n");
             return -EINVAL;
         }
     } else {
         if (!(vma->vm_flags & VM_READ)) {
             dprintk(q, 1, "invalid vma flags, VM_READ needed\n");
             return -EINVAL;
         }
     }
 
     mutex_lock(&q->mmap_lock);
 
     if (vb2_fileio_is_active(q)) {
         dprintk(q, 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(q, 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(q, 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(q, 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;
 
     /*
      * This combination is not allowed since a non-zero value of
      * q->min_buffers_needed can cause vb2_core_qbuf() to fail if
      * it has to call start_streaming(), and the Request API expects
      * that queueing a request (and thus queueing a buffer contained
      * in that request) will always succeed. There is no method of
      * propagating an error back to userspace.
      */
     if (WARN_ON(q->supports_requests && q->min_buffers_needed))
         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;
 
     if (q->name[0] == '\0')
         snprintf(q->name, sizeof(q->name), "%s-%p",
              q->is_output ? "out" : "cap", q);
 
     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;
 
     /*
      * poll_wait() MUST be called on the first invocation on all the
      * potential queues of interest, even if we are not interested in their
      * events during this first call. Failure to do so will result in
      * queue's events to be ignored because the poll_table won't be capable
      * of adding new wait queues thereafter.
      */
     poll_wait(file, &q->done_wq, wait);
 
     if (!q->is_output && !(req_events & (EPOLLIN | EPOLLRDNORM)))
         return 0;
     if (q->is_output && !(req_events & (EPOLLOUT | EPOLLWRNORM)))
         return 0;
 
     /*
      * 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(q, 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, 0, &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, 0, &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, 0, &fileio->count);
         kfree(fileio);
         dprintk(q, 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(q, 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(q, 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(q, 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(q, 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(q, 5, "reducing read count: %zd\n", count);
     }
 
     /*
      * Transfer data to userspace.
      */
     dprintk(q, 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(q, 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(q, 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(q, 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(q, 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(q, 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");
 MODULE_IMPORT_NS(DMA_BUF);