From: Gustavo Padovan <gustavo.pado...@collabora.com>

If V4L2_BUF_FLAG_OUT_FENCE flag is present on the QBUF call we create
an out_fence and send its fd to userspace in the fence_fd field as a
return arg for the QBUF call.

The fence is signaled on buffer_done(), when the job on the buffer is
finished.

v12: - Pass the fence_fd in vb2_qbuf for clarity.
     - Increase fence seqno if fence context if shared
     - Check get_unused_fd return

v11: - Return fence_fd to userpace only in the QBUF ioctl.
     - Rework implementation to avoid storing the sync_file
       as state, which is not really needed.

v10: - use -EIO for fence error (Hans Verkuil)
     - add comment around fence context creation (Hans Verkuil)

v9: - remove in-fences changes from this patch (Alex Courbot)
    - improve fence context creation (Hans Verkuil)
    - clean up out fences if vb2_core_qbuf() fails (Hans Verkuil)

v8: - return 0 as fence_fd if OUT_FENCE flag not used (Mauro)
    - fix crash when checking not using fences in vb2_buffer_done()

v7: - merge patch that add the infrastructure to out-fences into
      this one (Alex Courbot)
    - Do not install the fd if there is no fence. (Alex Courbot)
    - do not report error on requeueing, just WARN_ON_ONCE() (Hans)

v6: - get rid of the V4L2_EVENT_OUT_FENCE event. We always keep the
      ordering in vb2 for queueing in the driver, so the event is not
      necessary anymore and the out_fence_fd is sent back to userspace
      on QBUF call return arg
    - do not allow requeueing with out-fences, instead mark the buffer
      with an error and wake up to userspace.
    - send the out_fence_fd back to userspace on the fence_fd field

v5: - delay fd_install to DQ_EVENT (Hans)
    - if queue is fully ordered send OUT_FENCE event right away
      (Brian)
    - rename 'q->ordered' to 'q->ordered_in_driver'
    - merge change to implement OUT_FENCE event here

v4: - return the out_fence_fd in the BUF_QUEUED event(Hans)

v3: - add WARN_ON_ONCE(q->ordered) on requeueing (Hans)
    - set the OUT_FENCE flag if there is a fence pending (Hans)
    - call fd_install() after vb2_core_qbuf() (Hans)
    - clean up fence if vb2_core_qbuf() fails (Hans)
    - add list to store sync_file and fence for the next queued buffer

v2: check if the queue is ordered.

Signed-off-by: Gustavo Padovan <gustavo.pado...@collabora.com>
Signed-off-by: Ezequiel Garcia <ezequ...@collabora.com>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 113 +++++++++++++++++++++++-
 drivers/media/common/videobuf2/videobuf2-v4l2.c |  10 ++-
 drivers/media/dvb-core/dvb_vb2.c                |   2 +-
 include/media/videobuf2-core.h                  |  20 ++++-
 4 files changed, 136 insertions(+), 9 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c 
b/drivers/media/common/videobuf2/videobuf2-core.c
index 86b5ebe25263..edc2fdaf56de 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -25,6 +25,7 @@
 #include <linux/sched.h>
 #include <linux/freezer.h>
 #include <linux/kthread.h>
+#include <linux/sync_file.h>
 
 #include <media/videobuf2-core.h>
 #include <media/v4l2-ioctl.h>
@@ -380,6 +381,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum 
vb2_memory memory,
                        vb->planes[plane].length = plane_sizes[plane];
                        vb->planes[plane].min_length = plane_sizes[plane];
                }
+               vb->out_fence_fd = -1;
                q->bufs[vb->index] = vb;
 
                /* Allocate video buffer memory for the MMAP type */
@@ -976,10 +978,22 @@ static void vb2_process_buffer_done(struct vb2_buffer 
*vb, enum vb2_buffer_state
        case VB2_BUF_STATE_QUEUED:
                return;
        case VB2_BUF_STATE_REQUEUEING:
+               /* Requeuing with explicit synchronization, spit warning */
+               WARN_ON_ONCE(vb->out_fence);
+
                if (q->start_streaming_called)
                        __enqueue_in_driver(vb);
                return;
        default:
+               if (vb->out_fence) {
+                       if (state == VB2_BUF_STATE_ERROR)
+                               dma_fence_set_error(vb->out_fence, -EIO);
+                       dma_fence_signal(vb->out_fence);
+                       dma_fence_put(vb->out_fence);
+                       vb->out_fence = NULL;
+                       vb->out_fence_fd = -1;
+               }
+
                /* Inform any processes that may be waiting for buffers */
                wake_up(&q->done_wq);
                break;
@@ -1406,6 +1420,76 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned 
int index, void *pb)
 }
 EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
 
+static inline const char *vb2_fence_get_driver_name(struct dma_fence *fence)
+{
+       return "vb2_fence";
+}
+
+static inline const char *vb2_fence_get_timeline_name(struct dma_fence *fence)
+{
+       return "vb2_fence_timeline";
+}
+
+static inline bool vb2_fence_enable_signaling(struct dma_fence *fence)
+{
+       return true;
+}
+
+static const struct dma_fence_ops vb2_fence_ops = {
+       .get_driver_name = vb2_fence_get_driver_name,
+       .get_timeline_name = vb2_fence_get_timeline_name,
+       .enable_signaling = vb2_fence_enable_signaling,
+       .wait = dma_fence_default_wait,
+};
+
+static int vb2_setup_out_fence(struct vb2_queue *q, struct vb2_buffer *vb)
+{
+       struct sync_file *sync_file;
+       unsigned int seqno;
+       int ret, fd;
+
+       fd = get_unused_fd_flags(O_CLOEXEC);
+       if (fd < 0)
+               return fd;
+
+       /*
+        * The same context can be used only if the queue is ordered,
+        * so if the queue is ordered create one when the queueing start,
+        * otherwise create one for every buffer
+        */
+       if (call_qop(q, is_unordered, q)) {
+               q->out_fence_context = dma_fence_context_alloc(1);
+               seqno = 1;
+       } else {
+               seqno = q->out_fence_seqno++;
+       }
+
+       vb->out_fence = kzalloc(sizeof(*vb->out_fence), GFP_KERNEL);
+       if (!vb->out_fence) {
+               ret = -ENOMEM;
+               goto err_put_fd;
+       }
+       dma_fence_init(vb->out_fence, &vb2_fence_ops, &q->out_fence_lock,
+                      q->out_fence_context, seqno);
+
+       sync_file = sync_file_create(vb->out_fence);
+       if (!sync_file) {
+               ret = -ENOMEM;
+               goto err_free_fence;
+       }
+       fd_install(fd, sync_file->file);
+       vb->out_fence_fd = fd;
+       return 0;
+
+err_free_fence:
+       dma_fence_put(vb->out_fence);
+       vb->out_fence = NULL;
+err_put_fd:
+       put_unused_fd(vb->out_fence_fd);
+       vb->out_fence_fd = -1;
+       return ret;
+}
+
 /*
  * vb2_start_streaming() - Attempt to start streaming.
  * @q:         videobuf2 queue
@@ -1508,7 +1592,7 @@ static void vb2_qbuf_fence_cb(struct dma_fence *f, struct 
dma_fence_cb *cb)
 }
 
 int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
-                 struct dma_fence *in_fence)
+                 struct dma_fence *in_fence, int *out_fence_fd)
 {
        struct vb2_buffer *vb;
        int ret;
@@ -1540,6 +1624,7 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int 
index, void *pb,
        list_add_tail(&vb->queued_entry, &q->queued_list);
        q->queued_count++;
        q->waiting_for_buffers = false;
+       q->queueing_started = 1;
        vb->state = VB2_BUF_STATE_QUEUED;
 
        if (pb)
@@ -1600,6 +1685,20 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int 
index, void *pb,
                        goto err_release;
        }
 
+       if (out_fence_fd) {
+               *out_fence_fd = -1;
+               ret = vb2_setup_out_fence(q, vb);
+               if (ret) {
+                       dprintk(1, "failed to set up out-fence\n");
+                       goto err_release;
+               }
+
+               /* If we have successfully created an out-fence,
+                * return its fd.
+                */
+               *out_fence_fd = vb->out_fence_fd;
+       }
+
        /* Fill buffer information for userspace */
        if (pb)
                call_void_bufop(q, fill_user_buffer, vb, pb);
@@ -1864,6 +1963,7 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
        q->start_streaming_called = 0;
        q->queued_count = 0;
        q->error = 0;
+       q->queueing_started = 0;
 
        /*
         * Remove all buffers from videobuf's list...
@@ -2206,7 +2306,12 @@ int vb2_core_queue_init(struct vb2_queue *q)
        spin_lock_init(&q->done_lock);
        mutex_init(&q->mmap_lock);
        init_waitqueue_head(&q->done_wq);
+       spin_lock_init(&q->out_fence_lock);
 
+       if (!call_qop(q, is_unordered, q)) {
+               q->out_fence_context = dma_fence_context_alloc(1);
+               q->out_fence_seqno = 1;
+       }
        q->memory = VB2_MEMORY_UNKNOWN;
 
        if (q->buf_struct_size == 0)
@@ -2457,7 +2562,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int 
read)
                 * Queue all buffers.
                 */
                for (i = 0; i < q->num_buffers; i++) {
-                       ret = vb2_core_qbuf(q, i, NULL, NULL);
+                       ret = vb2_core_qbuf(q, i, NULL, NULL, NULL);
                        if (ret)
                                goto err_reqbufs;
                        fileio->bufs[i].queued = 1;
@@ -2636,7 +2741,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, 
char __user *data, size_
 
                if (copy_timestamp)
                        b->timestamp = ktime_get_ns();
-               ret = vb2_core_qbuf(q, index, NULL, NULL);
+               ret = vb2_core_qbuf(q, index, NULL, NULL, NULL);
                dprintk(5, "vb2_dbuf result: %d\n", ret);
                if (ret)
                        return ret;
@@ -2739,7 +2844,7 @@ static int vb2_thread(void *data)
                if (copy_timestamp)
                        vb->timestamp = ktime_get_ns();
                if (!threadio->stop)
-                       ret = vb2_core_qbuf(q, vb->index, NULL, NULL);
+                       ret = vb2_core_qbuf(q, vb->index, NULL, NULL, NULL);
                call_void_qop(q, wait_prepare, q);
                if (ret || threadio->stop)
                        break;
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c 
b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index ac14cc8ab1c5..b4908d0432c6 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -588,8 +588,9 @@ EXPORT_SYMBOL_GPL(vb2_create_bufs);
 
 int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
 {
+       bool get_out_fence = b->flags & V4L2_BUF_FLAG_OUT_FENCE;
        struct dma_fence *in_fence = NULL;
-       int ret;
+       int ret, fence_fd;
 
        if (vb2_fileio_is_active(q)) {
                dprintk(1, "file io in progress\n");
@@ -609,7 +610,12 @@ int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
                }
        }
 
-       return vb2_core_qbuf(q, b->index, b, in_fence);
+       ret = vb2_core_qbuf(q, b->index, b, in_fence,
+                           get_out_fence ? &fence_fd : NULL);
+       if (ret)
+               return ret;
+       b->fence_fd = fence_fd;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(vb2_qbuf);
 
diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
index 7da53f10db1a..5c1523a8accc 100644
--- a/drivers/media/dvb-core/dvb_vb2.c
+++ b/drivers/media/dvb-core/dvb_vb2.c
@@ -385,7 +385,7 @@ int dvb_vb2_qbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer 
*b)
 {
        int ret;
 
-       ret = vb2_core_qbuf(&ctx->vb_q, b->index, b, NULL);
+       ret = vb2_core_qbuf(&ctx->vb_q, b->index, b, NULL, NULL);
        if (ret) {
                dprintk(1, "[%s] index=%d errno=%d\n", ctx->name,
                        b->index, ret);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index ddd555f59dbf..6abe133d1c9a 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -262,6 +262,9 @@ struct vb2_buffer {
         *                      using the buffer (queueing to the driver)
         * fence_cb:            fence callback information
         * qbuf_work:           work for deferred qbuf operation
+        * out_fence_fd:        the out_fence_fd to be shared with userspace.
+        * out_fence:           the out-fence associated with the buffer once
+        *                      it is queued to the driver.
         */
        struct kref             refcount;
        enum vb2_buffer_state   state;
@@ -274,6 +277,9 @@ struct vb2_buffer {
        struct dma_fence_cb     fence_cb;
        struct work_struct      qbuf_work;
 
+       int                     out_fence_fd;
+       struct dma_fence        *out_fence;
+
 #ifdef CONFIG_VIDEO_ADV_DEBUG
        /*
         * Counters for how often these buffer-related ops are
@@ -550,6 +556,10 @@ struct vb2_buf_ops {
  * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
  *             last decoded buffer was already dequeued. Set for capture queues
  *             when a buffer with the %V4L2_BUF_FLAG_LAST is dequeued.
+ * @queueing_started: if queueing has started. Currently used to determine
+ *             if an out_fence_context is needed.
+ * @out_fence_context: the fence context for the out fences
+ * @out_fence_seqno: the fence seqno to use, if the context is shared
  * @fileio:    file io emulator internal data, used only if emulator is active
  * @threadio:  thread io internal data, used only if thread is active
  */
@@ -602,6 +612,11 @@ struct vb2_queue {
        unsigned int                    is_output:1;
        unsigned int                    copy_timestamp:1;
        unsigned int                    last_buffer_dequeued:1;
+       unsigned int                    queueing_started:1;
+
+       u64                             out_fence_context;
+       unsigned int                    out_fence_seqno;
+       spinlock_t                      out_fence_lock;
 
        struct vb2_fileio_data          *fileio;
        struct vb2_threadio_data        *threadio;
@@ -800,7 +815,8 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int 
index, void *pb);
  * @index:     id number of the buffer
  * @pb:                buffer structure passed from userspace to
  *             v4l2_ioctl_ops->vidioc_qbuf handler in driver
- * @in_fence:  in-fence to wait on before queueing the buffer
+ * @in_fence:  optioanl in-fence to wait on before queueing the buffer
+ * @out_fence_fd: optional pointer to store a newly created out-fence fd
  *
  * Videobuf2 core helper to implement VIDIOC_QBUF() operation. It is called
  * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
@@ -816,7 +832,7 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int 
index, void *pb);
  * Return: returns zero on success; an error code otherwise.
  */
 int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
-                 struct dma_fence *in_fence);
+                 struct dma_fence *in_fence, int *out_fence_fd);
 
 /**
  * vb2_core_dqbuf() - Dequeue a buffer to the userspace
-- 
2.16.3

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