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[PATCH v3 00/15] V4L2 Explicit Synchronization support

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  [PATCH v3 00/15] V4L2 Explicit Synchronization support Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 14/15] fs/files: export close_fd() symbol Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
      Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Eric Biggers <ebiggers3@gmail.com> - 2017-09-07 21:00 +0200
      Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Al Viro <viro@ZenIV.linux.org.uk> - 2017-09-07 22:40 +0200
        Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 23:30 +0200
          Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Al Viro <viro@ZenIV.linux.org.uk> - 2017-09-08 00:10 +0200
      Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Hans Verkuil <hverkuil@xs4all.nl> - 2017-09-08 00:10 +0200
        Re: [PATCH v3 14/15] fs/files: export close_fd() symbol Gustavo Padovan <gustavo.padovan@collabora.com> - 2017-09-08 00:20 +0200
    [PATCH v3 08/15] [media] vb2: add .buffer_queued() to notify queueing in the driver Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 03/15] [media] vb2: check earlier if stream can be started Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 07/15] [media] v4l: add V4L2_EVENT_BUF_QUEUED event Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 12/15] [media] vb2: add videobuf2 dma-buf fence helpers Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 09/15] [media] v4l: add support to BUF_QUEUED event Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 02/15] [media] vb2: add explicit fence user API Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200
    [PATCH v3 13/15] [media] vb2: add infrastructure to support out-fences Gustavo Padovan <gustavo@padovan.org> - 2017-09-07 20:50 +0200

#1728380 — [PATCH v3 00/15] V4L2 Explicit Synchronization support

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

Hi,

Refer to the documentation on the first patch for the details. The previous
iteration is here: https://www.mail-archive.com/linux-media@vger.kernel.org/msg118077.html

The 2nd patch proposes an userspace API for fences, then on patch 3 we
prepare to the addition of in-fences in patch 4, by introducing the
infrastructure on vb2 to wait on an in-fence signal before queueing the
buffer in the driver.

Patch 5 fix uvc v4l2 event handling and patch 6 configure q->dev for
vivid drivers to enable to subscribe and dequeue events on it.

Patches 7-9 enables support to notify BUF_QUEUED events, the event send
to userspace the out-fence fd and the index of the buffer that was queued.

Patches 10-11 add support to mark queues as ordered. Finally patches 12
and 13 add more fence infrastructure to support out-fences, patch 13 exposes
close_fd() and patch 14 adds support to out-fences. 

It only works for ordered queues for now, see open question at the end
of the letter.

Test tool can be found at:
https://git.collabora.com/cgit/user/padovan/v4l2-test.git/

Main Changes
------------

* out-fences: change in behavior: the out-fence fd now comes out of the
BUF_QUEUED event along with the buffer id.

All other changes are recorded on the patches' commit messages.

Open Questions
--------------

* non-ordered devices, like m2m: I've been thinking a lot about those
  and one possibility is to have a way to tell userspace that the queue
  is not ordered and then associate the fence with the current buffer in
  QBUF instead of the next one to be queued. Of course, there won't be
  any ordering between the fences. But it may be enough for userspace to
  take advantage of Explicit Synchronization in such cases. Any
  thoughts?

* OUTPUT devices and in-fence. If I understood OUTPUT devices correctly
  it is desirable to queue the buffers to the driver in the same order
  we received them from userspace. If that is correct, shouldn't we add
  some mechanism to prevent buffer whose fence signaled to jump ahead of
  others?

Gustavo Padovan (14):
  [media] v4l: Document explicit synchronization behaviour
  [media] vb2: add explicit fence user API
  [media] vb2: check earlier if stream can be started
  [media] vb2: add in-fence support to QBUF
  [media] uvc: enable subscriptions to other events
  [media] vivid: assign the specific device to the vb2_queue->dev
  [media] v4l: add V4L2_EVENT_BUF_QUEUED event
  [media] vb2: add .buffer_queued() to notify queueing in the driver
  [media] v4l: add support to BUF_QUEUED event
  [media] vb2: add 'ordered' property to queues
  [media] vivid: mark vivid queues as ordered
  [media] vb2: add infrastructure to support out-fences
  fs/files: export close_fd() symbol
  [media] vb2: add out-fence support to QBUF

Javier Martinez Canillas (1):
  [media] vb2: add videobuf2 dma-buf fence helpers

 Documentation/media/uapi/v4l/buffer.rst         |  19 ++
 Documentation/media/uapi/v4l/vidioc-dqevent.rst |  23 +++
 Documentation/media/uapi/v4l/vidioc-qbuf.rst    |  31 ++++
 Documentation/media/videodev2.h.rst.exceptions  |   1 +
 drivers/android/binder.c                        |   2 +-
 drivers/media/platform/vivid/vivid-core.c       |  15 +-
 drivers/media/usb/cpia2/cpia2_v4l.c             |   2 +-
 drivers/media/usb/uvc/uvc_v4l2.c                |   2 +-
 drivers/media/v4l2-core/Kconfig                 |   1 +
 drivers/media/v4l2-core/v4l2-compat-ioctl32.c   |   4 +-
 drivers/media/v4l2-core/v4l2-ctrls.c            |   6 +-
 drivers/media/v4l2-core/videobuf2-core.c        | 221 ++++++++++++++++++++++--
 drivers/media/v4l2-core/videobuf2-v4l2.c        |  63 ++++++-
 fs/file.c                                       |   5 +-
 fs/open.c                                       |   2 +-
 include/linux/fdtable.h                         |   2 +-
 include/media/videobuf2-core.h                  |  63 ++++++-
 include/media/videobuf2-fence.h                 |  49 ++++++
 include/uapi/linux/videodev2.h                  |  15 +-
 19 files changed, 489 insertions(+), 37 deletions(-)
 create mode 100644 include/media/videobuf2-fence.h

-- 
2.13.5

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#1728381 — [PATCH v3 14/15] fs/files: export close_fd() symbol

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

Rename __close_fd() to close_fd() and export it to be able close files
in modules using file descriptors.

The usecase that motivates this change happens in V4L2 where we send
events to userspace with a fd that has file installed in it. But if for
some reason we have to cancel the video stream we need to close the files
that haven't been shared with userspace yet. Thus the export of
close_fd() becomes necessary.

fd_install() happens when we call an ioctl to queue a buffer, but we only
share the fd with userspace later, and that may happen in a kernel thread
instead.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Riley Andrews <riandrews@android.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
This is more like a question, I don't know how unhappy people will be with
this proposal to expose close_fd(). I'm all ears for more interesting
ways of doing it!
---
 drivers/android/binder.c | 2 +-
 fs/file.c                | 5 +++--
 fs/open.c                | 2 +-
 include/linux/fdtable.h  | 2 +-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index f7665c31feca..5a9bc73012df 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -440,7 +440,7 @@ static long task_close_fd(struct binder_proc *proc, unsigned int fd)
 	if (proc->files == NULL)
 		return -ESRCH;
 
-	retval = __close_fd(proc->files, fd);
+	retval = close_fd(proc->files, fd);
 	/* can't restart close syscall because file table entry was cleared */
 	if (unlikely(retval == -ERESTARTSYS ||
 		     retval == -ERESTARTNOINTR ||
diff --git a/fs/file.c b/fs/file.c
index 1fc7fbbb4510..111d387ac190 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -618,7 +618,7 @@ EXPORT_SYMBOL(fd_install);
 /*
  * The same warnings as for __alloc_fd()/__fd_install() apply here...
  */
-int __close_fd(struct files_struct *files, unsigned fd)
+int close_fd(struct files_struct *files, unsigned fd)
 {
 	struct file *file;
 	struct fdtable *fdt;
@@ -640,6 +640,7 @@ int __close_fd(struct files_struct *files, unsigned fd)
 	spin_unlock(&files->file_lock);
 	return -EBADF;
 }
+EXPORT_SYMBOL(close_fd);
 
 void do_close_on_exec(struct files_struct *files)
 {
@@ -856,7 +857,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
 	struct files_struct *files = current->files;
 
 	if (!file)
-		return __close_fd(files, fd);
+		return close_fd(files, fd);
 
 	if (fd >= rlimit(RLIMIT_NOFILE))
 		return -EBADF;
diff --git a/fs/open.c b/fs/open.c
index 35bb784763a4..30907d967443 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1152,7 +1152,7 @@ EXPORT_SYMBOL(filp_close);
  */
 SYSCALL_DEFINE1(close, unsigned int, fd)
 {
-	int retval = __close_fd(current->files, fd);
+	int retval = close_fd(current->files, fd);
 
 	/* can't restart close syscall because file table entry was cleared */
 	if (unlikely(retval == -ERESTARTSYS ||
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 6e84b2cae6ad..511fd38d5e4b 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -115,7 +115,7 @@ extern int __alloc_fd(struct files_struct *files,
 		      unsigned start, unsigned end, unsigned flags);
 extern void __fd_install(struct files_struct *files,
 		      unsigned int fd, struct file *file);
-extern int __close_fd(struct files_struct *files,
+extern int close_fd(struct files_struct *files,
 		      unsigned int fd);
 
 extern struct kmem_cache *files_cachep;
-- 
2.13.5

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#1728390 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

On Thu, Sep 07, 2017 at 03:42:25PM -0300, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
> 
> Rename __close_fd() to close_fd() and export it to be able close files
> in modules using file descriptors.
> 
> The usecase that motivates this change happens in V4L2 where we send
> events to userspace with a fd that has file installed in it. But if for
> some reason we have to cancel the video stream we need to close the files
> that haven't been shared with userspace yet. Thus the export of
> close_fd() becomes necessary.
> 
> fd_install() happens when we call an ioctl to queue a buffer, but we only
> share the fd with userspace later, and that may happen in a kernel thread
> instead.

What do you mean?  A file descriptor is shared with userspace as soon as it's
installed in the fdtable by fd_install().  As soon as it's there, another thread
can use it (or close it, duplicate it, etc.), even before the syscall that
installed it returns...

Eric

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#1728420 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

On Thu, Sep 07, 2017 at 03:42:25PM -0300, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
> 
> Rename __close_fd() to close_fd() and export it to be able close files
> in modules using file descriptors.
> 
> The usecase that motivates this change happens in V4L2 where we send
> events to userspace with a fd that has file installed in it. But if for
> some reason we have to cancel the video stream we need to close the files
> that haven't been shared with userspace yet. Thus the export of
> close_fd() becomes necessary.
> 
> fd_install() happens when we call an ioctl to queue a buffer, but we only
> share the fd with userspace later, and that may happen in a kernel thread
> instead.

NAK.  As soon as the reference is in descriptor table, you *can't* do anything
to it.  This "sharing" part is complete BS - being _told_ that descriptor is
there does not matter at all.  That descriptor might be hit with dup2() as
soon as fd_install() has happened.  Or be closed, or any number of other things.

You can not take it back.  Once fd_install() is done, it's fucking done, period.
If V4L2 requires removing it from descriptor table, it's a shitty API and needs
to be fixed.

Again, NAK.

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#1728450 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

2017-09-07 Al Viro <viro@ZenIV.linux.org.uk>:

> On Thu, Sep 07, 2017 at 03:42:25PM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.com>
> > 
> > Rename __close_fd() to close_fd() and export it to be able close files
> > in modules using file descriptors.
> > 
> > The usecase that motivates this change happens in V4L2 where we send
> > events to userspace with a fd that has file installed in it. But if for
> > some reason we have to cancel the video stream we need to close the files
> > that haven't been shared with userspace yet. Thus the export of
> > close_fd() becomes necessary.
> > 
> > fd_install() happens when we call an ioctl to queue a buffer, but we only
> > share the fd with userspace later, and that may happen in a kernel thread
> > instead.
> 
> NAK.  As soon as the reference is in descriptor table, you *can't* do anything
> to it.  This "sharing" part is complete BS - being _told_ that descriptor is
> there does not matter at all.  That descriptor might be hit with dup2() as
> soon as fd_install() has happened.  Or be closed, or any number of other things.
> 
> You can not take it back.  Once fd_install() is done, it's fucking done, period.
> If V4L2 requires removing it from descriptor table, it's a shitty API and needs
> to be fixed.

Sorry for my lack of knowledge here and thank you for the explanation,
things are a lot clear to me. For some reasons I were trying to delay
the sharing of the fd to a event later. I can delay the install of it
but that my require __fd_install() to be available and exportedi as it
may happen in a thread, but I believe you wouldn't be okay with that either,
is that so?

Gustavo

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#1728469 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

On Thu, Sep 07, 2017 at 06:22:45PM -0300, Gustavo Padovan wrote:

> Sorry for my lack of knowledge here and thank you for the explanation,
> things are a lot clear to me. For some reasons I were trying to delay
> the sharing of the fd to a event later. I can delay the install of it
> but that my require __fd_install() to be available and exportedi as it
> may happen in a thread, but I believe you wouldn't be okay with that either,
> is that so?

Only if it has been given a reference to descriptor table to start with.
Which reference should've been acquired by the target process itself.

Why bother, anyway?  You need to handle the case when the stream has
ended just after you'd copied the value to userland; at that point you
obviously can't go hunting for all references to struct file in question,
so you have to guaratee that methods will start giving an error from
that point on.  What's the problem with just leaving it installed?

Both userland and kernel must cope with that sort of thing anyway, so
what does removing it from descriptor table and not reporting it buy
you?  AFAICS, it's an extra layer of complexity for no good reason -
you are not getting it offset by simplifications anywhere else...

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#1728470 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

On 09/07/2017 08:42 PM, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
> 
> Rename __close_fd() to close_fd() and export it to be able close files
> in modules using file descriptors.
> 
> The usecase that motivates this change happens in V4L2 where we send
> events to userspace with a fd that has file installed in it. But if for
> some reason we have to cancel the video stream we need to close the files
> that haven't been shared with userspace yet. Thus the export of
> close_fd() becomes necessary.
> 
> fd_install() happens when we call an ioctl to queue a buffer, but we only
> share the fd with userspace later, and that may happen in a kernel thread
> instead.

This isn't the way to do this.

You should only create the out fence file descriptor when userspace dequeues
(i.e. calls VIDIOC_DQEVENT) the BUF_QUEUED event. That's when you give it to
userspace and at that moment closing the fd is the responsibility of userspace.
There is no point creating it earlier anyway since userspace can't get to it
until it dequeues the event.

It does mean some more work in the V4L2 core since you need to hook into the
DQEVENT code in order to do this.

Regards,

	Hans

> 
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Riley Andrews <riandrews@android.com>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
> ---
> This is more like a question, I don't know how unhappy people will be with
> this proposal to expose close_fd(). I'm all ears for more interesting
> ways of doing it!
> ---
>  drivers/android/binder.c | 2 +-
>  fs/file.c                | 5 +++--
>  fs/open.c                | 2 +-
>  include/linux/fdtable.h  | 2 +-
>  4 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index f7665c31feca..5a9bc73012df 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -440,7 +440,7 @@ static long task_close_fd(struct binder_proc *proc, unsigned int fd)
>  	if (proc->files == NULL)
>  		return -ESRCH;
>  
> -	retval = __close_fd(proc->files, fd);
> +	retval = close_fd(proc->files, fd);
>  	/* can't restart close syscall because file table entry was cleared */
>  	if (unlikely(retval == -ERESTARTSYS ||
>  		     retval == -ERESTARTNOINTR ||
> diff --git a/fs/file.c b/fs/file.c
> index 1fc7fbbb4510..111d387ac190 100644
> --- a/fs/file.c
> +++ b/fs/file.c
> @@ -618,7 +618,7 @@ EXPORT_SYMBOL(fd_install);
>  /*
>   * The same warnings as for __alloc_fd()/__fd_install() apply here...
>   */
> -int __close_fd(struct files_struct *files, unsigned fd)
> +int close_fd(struct files_struct *files, unsigned fd)
>  {
>  	struct file *file;
>  	struct fdtable *fdt;
> @@ -640,6 +640,7 @@ int __close_fd(struct files_struct *files, unsigned fd)
>  	spin_unlock(&files->file_lock);
>  	return -EBADF;
>  }
> +EXPORT_SYMBOL(close_fd);
>  
>  void do_close_on_exec(struct files_struct *files)
>  {
> @@ -856,7 +857,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
>  	struct files_struct *files = current->files;
>  
>  	if (!file)
> -		return __close_fd(files, fd);
> +		return close_fd(files, fd);
>  
>  	if (fd >= rlimit(RLIMIT_NOFILE))
>  		return -EBADF;
> diff --git a/fs/open.c b/fs/open.c
> index 35bb784763a4..30907d967443 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1152,7 +1152,7 @@ EXPORT_SYMBOL(filp_close);
>   */
>  SYSCALL_DEFINE1(close, unsigned int, fd)
>  {
> -	int retval = __close_fd(current->files, fd);
> +	int retval = close_fd(current->files, fd);
>  
>  	/* can't restart close syscall because file table entry was cleared */
>  	if (unlikely(retval == -ERESTARTSYS ||
> diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
> index 6e84b2cae6ad..511fd38d5e4b 100644
> --- a/include/linux/fdtable.h
> +++ b/include/linux/fdtable.h
> @@ -115,7 +115,7 @@ extern int __alloc_fd(struct files_struct *files,
>  		      unsigned start, unsigned end, unsigned flags);
>  extern void __fd_install(struct files_struct *files,
>  		      unsigned int fd, struct file *file);
> -extern int __close_fd(struct files_struct *files,
> +extern int close_fd(struct files_struct *files,
>  		      unsigned int fd);
>  
>  extern struct kmem_cache *files_cachep;
> 

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#1728472 — Re: [PATCH v3 14/15] fs/files: export close_fd() symbol

On Fri, 2017-09-08 at 00:09 +0200, Hans Verkuil wrote:
> On 09/07/2017 08:42 PM, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.com>
> > 
> > Rename __close_fd() to close_fd() and export it to be able close
> > files
> > in modules using file descriptors.
> > 
> > The usecase that motivates this change happens in V4L2 where we
> > send
> > events to userspace with a fd that has file installed in it. But if
> > for
> > some reason we have to cancel the video stream we need to close the
> > files
> > that haven't been shared with userspace yet. Thus the export of
> > close_fd() becomes necessary.
> > 
> > fd_install() happens when we call an ioctl to queue a buffer, but
> > we only
> > share the fd with userspace later, and that may happen in a kernel
> > thread
> > instead.
> 
> This isn't the way to do this.
> 
> You should only create the out fence file descriptor when userspace
> dequeues
> (i.e. calls VIDIOC_DQEVENT) the BUF_QUEUED event. That's when you
> give it to
> userspace and at that moment closing the fd is the responsibility of
> userspace.
> There is no point creating it earlier anyway since userspace can't
> get to it
> until it dequeues the event.
> 
> It does mean some more work in the V4L2 core since you need to hook
> into the
> DQEVENT code in order to do this.

Right, that makes a lot more sense. I'll change the implementation so
it can reflecting that. Thanks.

Gustavo

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#1728382 — [PATCH v3 08/15] [media] vb2: add .buffer_queued() to notify queueing in the driver

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

With the upcoming explicit synchronization support to V4L2 we need a
way to notify userspace when buffers are queued to the driver - buffers
with fences attached to it can only be queued once the fence signal, so
the queueing to the driver might be deferred.

Yet, userspace still wants to be notified, so the buffer_queued() callback
was added to vb2_buf_ops for that purpose.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 include/media/videobuf2-core.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 41cda762ff0a..5ed8d3402474 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -415,6 +415,8 @@ struct vb2_ops {
  *			will return an error.
  * @copy_timestamp:	copy the timestamp from a userspace structure to
  *			the vb2_buffer struct.
+ * @buffer_queued:	VB2 uses this to notify the VB2-client that the buffer
+ *			was queued to the driver.
  */
 struct vb2_buf_ops {
 	int (*verify_planes_array)(struct vb2_buffer *vb, const void *pb);
@@ -422,6 +424,7 @@ struct vb2_buf_ops {
 	int (*fill_vb2_buffer)(struct vb2_buffer *vb, const void *pb,
 				struct vb2_plane *planes);
 	void (*copy_timestamp)(struct vb2_buffer *vb, const void *pb);
+	void (*buffer_queued)(struct vb2_buffer *vb);
 };
 
 /**
-- 
2.13.5

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#1728383 — [PATCH v3 03/15] [media] vb2: check earlier if stream can be started

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

To support explicit synchronization we need to run all operations that can
fail before we queue the buffer to the driver. With fences the queueing
will be delayed if the fence is not signaled yet and it will be better if
such callback do not fail.

For that we move the vb2_start_streaming() before the queuing for the
buffer may happen.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index cb115ba6a1d2..60f8b582396a 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1399,29 +1399,27 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *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 already streaming, give the buffer to driver for processing.
+	 * If not, the buffer will be given to driver on next streamon.
 	 */
 	if (q->streaming && !q->start_streaming_called &&
 	    q->queued_count >= q->min_buffers_needed) {
 		ret = vb2_start_streaming(q);
 		if (ret)
 			return ret;
+	} else 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);
+
 	dprintk(2, "qbuf of buffer %d succeeded\n", vb->index);
 	return 0;
 }
-- 
2.13.5

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#1728384 — [PATCH v3 07/15] [media] v4l: add V4L2_EVENT_BUF_QUEUED event

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

Add a new event the userspace can subscribe to receive notifications
when a buffer is queued onto the driver. The event provides the index of
the queued buffer.

v2: - Add missing Documentation (Mauro)

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 Documentation/media/uapi/v4l/vidioc-dqevent.rst | 23 +++++++++++++++++++++++
 Documentation/media/videodev2.h.rst.exceptions  |  1 +
 include/uapi/linux/videodev2.h                  | 11 +++++++++++
 3 files changed, 35 insertions(+)

diff --git a/Documentation/media/uapi/v4l/vidioc-dqevent.rst b/Documentation/media/uapi/v4l/vidioc-dqevent.rst
index fcd9c933870d..55f9dbdca6ec 100644
--- a/Documentation/media/uapi/v4l/vidioc-dqevent.rst
+++ b/Documentation/media/uapi/v4l/vidioc-dqevent.rst
@@ -78,6 +78,10 @@ call.
       - ``src_change``
       - Event data for event V4L2_EVENT_SOURCE_CHANGE.
     * -
+      - struct :c:type:`v4l2_event_buf_queued`
+      - ``buf_queued``
+      - Event data for event V4L2_EVENT_BUF_QUEUED.
+    * -
       - __u8
       - ``data``\ [64]
       - Event data. Defined by the event type. The union should be used to
@@ -337,6 +341,25 @@ call.
 	each cell in the motion detection grid, then that all cells are
 	automatically assigned to the default region 0.
 
+.. c:type:: v4l2_event_buf_queued
+
+.. flat-table:: struct v4l2_event_buf_queued
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u32
+      - ``index``
+      - The index of the buffer that was queued to the driver.
+    * - __s32
+      - ``out_fence_fd``
+      - The out-fence file descriptor of the buffer that was queued to
+	the driver. It will signal when the buffer is ready, or if an
+	error happens.
+
+
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
 
 
 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions
index a5cb0a8686ac..4e014b1d0317 100644
--- a/Documentation/media/videodev2.h.rst.exceptions
+++ b/Documentation/media/videodev2.h.rst.exceptions
@@ -462,6 +462,7 @@ replace define V4L2_EVENT_CTRL event-type
 replace define V4L2_EVENT_FRAME_SYNC event-type
 replace define V4L2_EVENT_SOURCE_CHANGE event-type
 replace define V4L2_EVENT_MOTION_DET event-type
+replace define V4L2_EVENT_BUF_QUEUED event-type
 replace define V4L2_EVENT_PRIVATE_START event-type
 
 replace define V4L2_EVENT_CTRL_CH_VALUE ctrl-changes-flags
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index e5abab9a908c..e2ec0b66f490 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -2158,6 +2158,7 @@ struct v4l2_streamparm {
 #define V4L2_EVENT_FRAME_SYNC			4
 #define V4L2_EVENT_SOURCE_CHANGE		5
 #define V4L2_EVENT_MOTION_DET			6
+#define V4L2_EVENT_BUF_QUEUED			7
 #define V4L2_EVENT_PRIVATE_START		0x08000000
 
 /* Payload for V4L2_EVENT_VSYNC */
@@ -2210,6 +2211,15 @@ struct v4l2_event_motion_det {
 	__u32 region_mask;
 };
 
+/**
+ * struct v4l2_event_buf_queued - buffer queued in the driver event
+ * @index:		index of the buffer queued in the driver
+ */
+struct v4l2_event_buf_queued {
+	__u32 index;
+	__s32 out_fence_fd;
+};
+
 struct v4l2_event {
 	__u32				type;
 	union {
@@ -2218,6 +2228,7 @@ struct v4l2_event {
 		struct v4l2_event_frame_sync	frame_sync;
 		struct v4l2_event_src_change	src_change;
 		struct v4l2_event_motion_det	motion_det;
+		struct v4l2_event_buf_queued	buf_queued;
 		__u8				data[64];
 	} u;
 	__u32				pending;
-- 
2.13.5

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#1728385 — [PATCH v3 12/15] [media] vb2: add videobuf2 dma-buf fence helpers

From: Javier Martinez Canillas <javier@osg.samsung.com>

Add a videobuf2-fence.h header file that contains different helpers
for DMA buffer sharing explicit fence support in videobuf2.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 include/media/videobuf2-fence.h | 49 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 include/media/videobuf2-fence.h

diff --git a/include/media/videobuf2-fence.h b/include/media/videobuf2-fence.h
new file mode 100644
index 000000000000..ed5612ca03d6
--- /dev/null
+++ b/include/media/videobuf2-fence.h
@@ -0,0 +1,49 @@
+/*
+ * videobuf2-fence.h - DMA buffer sharing fence helpers for videobuf 2
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ *
+ * 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.
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/slab.h>
+
+static DEFINE_SPINLOCK(vb2_fence_lock);
+
+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 inline struct dma_fence *vb2_fence_alloc(void)
+{
+	struct dma_fence *vb2_fence = kzalloc(sizeof(*vb2_fence), GFP_KERNEL);
+
+	if (!vb2_fence)
+		return NULL;
+
+	dma_fence_init(vb2_fence, &vb2_fence_ops, &vb2_fence_lock,
+		       dma_fence_context_alloc(1), 1);
+
+	return vb2_fence;
+}
-- 
2.13.5

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#1728387 — [PATCH v3 09/15] [media] v4l: add support to BUF_QUEUED event

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

Implement the needed pieces to let userspace subscribe for
V4L2_EVENT_BUF_QUEUED events. Videobuf2 will queue the event for the
DQEVENT ioctl.

v3:	- Do not call v4l2 event API from vb2 (Mauro)

v2:	- Use VIDEO_MAX_FRAME to allocate room for events at
	v4l2_event_subscribe() (Hans)

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 drivers/media/v4l2-core/v4l2-ctrls.c     |  6 +++++-
 drivers/media/v4l2-core/videobuf2-core.c |  2 ++
 drivers/media/v4l2-core/videobuf2-v4l2.c | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index dd1db678718c..17d4b9e3eec6 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -3438,8 +3438,12 @@ EXPORT_SYMBOL(v4l2_ctrl_log_status);
 int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
 				const struct v4l2_event_subscription *sub)
 {
-	if (sub->type == V4L2_EVENT_CTRL)
+	switch (sub->type) {
+	case V4L2_EVENT_CTRL:
 		return v4l2_event_subscribe(fh, sub, 0, &v4l2_ctrl_sub_ev_ops);
+	case V4L2_EVENT_BUF_QUEUED:
+		return v4l2_event_subscribe(fh, sub, VIDEO_MAX_FRAME, NULL);
+	}
 	return -EINVAL;
 }
 EXPORT_SYMBOL(v4l2_ctrl_subscribe_event);
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index b19c1bc4b083..bbbae0eed567 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1231,6 +1231,8 @@ static void __enqueue_in_driver(struct vb2_buffer *vb)
 	trace_vb2_buf_queue(q, vb);
 
 	call_void_vb_qop(vb, buf_queue, vb);
+
+	call_void_bufop(q, buffer_queued, vb);
 }
 
 static int __buf_prepare(struct vb2_buffer *vb, const void *pb)
diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
index 8c322cd1b346..bbfcd054e6f6 100644
--- a/drivers/media/v4l2-core/videobuf2-v4l2.c
+++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
@@ -138,6 +138,19 @@ static void __copy_timestamp(struct vb2_buffer *vb, const void *pb)
 	}
 };
 
+static void __buffer_queued(struct vb2_buffer *vb)
+{
+	struct video_device *vdev = to_video_device(vb->vb2_queue->dev);
+	struct v4l2_fh *fh = vdev->queue->owner;
+	struct v4l2_event event;
+
+	memset(&event, 0, sizeof(event));
+	event.type = V4L2_EVENT_BUF_QUEUED;
+	event.u.buf_queued.index = vb->index;
+
+	v4l2_event_queue_fh(fh, &event);
+}
+
 static void vb2_warn_zero_bytesused(struct vb2_buffer *vb)
 {
 	static bool check_once;
@@ -455,6 +468,7 @@ static const struct vb2_buf_ops v4l2_buf_ops = {
 	.fill_user_buffer	= __fill_v4l2_buffer,
 	.fill_vb2_buffer	= __fill_vb2_buffer,
 	.copy_timestamp		= __copy_timestamp,
+	.buffer_queued		= __buffer_queued,
 };
 
 /**
-- 
2.13.5

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#1728388 — [PATCH v3 02/15] [media] vb2: add explicit fence user API

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

Turn the reserved2 field into fence_fd that we will use to send
an in-fence to the kernel and return an out-fence from the kernel to
userspace.

Two new flags were added, V4L2_BUF_FLAG_IN_FENCE, that should be used
when sending a fence to the kernel to be waited on, and
V4L2_BUF_FLAG_OUT_FENCE, to ask the kernel to give back an out-fence.

v2: add documentation

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 Documentation/media/uapi/v4l/buffer.rst       | 19 +++++++++++++++++++
 drivers/media/usb/cpia2/cpia2_v4l.c           |  2 +-
 drivers/media/v4l2-core/v4l2-compat-ioctl32.c |  4 ++--
 drivers/media/v4l2-core/videobuf2-v4l2.c      |  2 +-
 include/uapi/linux/videodev2.h                |  4 +++-
 5 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst
index ae6ee73f151c..664507ad06c6 100644
--- a/Documentation/media/uapi/v4l/buffer.rst
+++ b/Documentation/media/uapi/v4l/buffer.rst
@@ -648,6 +648,25 @@ Buffer Flags
       - Start Of Exposure. The buffer timestamp has been taken when the
 	exposure of the frame has begun. This is only valid for the
 	``V4L2_BUF_TYPE_VIDEO_CAPTURE`` buffer type.
+    * .. _`V4L2-BUF-FLAG-IN-FENCE`:
+
+      - ``V4L2_BUF_FLAG_IN_FENCE``
+      - 0x00200000
+      - Ask V4L2 to wait on fence passed in ``fence_fd`` field. The buffer
+	won't be queued to the driver until the fence signals.
+
+    * .. _`V4L2-BUF-FLAG-OUT-FENCE`:
+
+      - ``V4L2_BUF_FLAG_OUT_FENCE``
+      - 0x00400000
+      - Request a fence for the next buffer to be queued to V4L2 driver.
+	The fence received back through the ``fence_fd`` field  doesn't
+	necessarily relate to the current buffer in the
+	:ref:`VIDIOC_QBUF <VIDIOC_QBUF>` ioctl. Although, most of the time
+	the fence will relate to the current buffer it can't be guaranteed.
+	So to tell userspace which buffer is associated to the out_fence,
+	one should listen for the ``V4L2_EVENT_BUF_QUEUED`` event that
+	provide the id of the buffer when it is queued to the V4L2 driver.
 
 
 
diff --git a/drivers/media/usb/cpia2/cpia2_v4l.c b/drivers/media/usb/cpia2/cpia2_v4l.c
index 3dedd83f0b19..6cde686bf44c 100644
--- a/drivers/media/usb/cpia2/cpia2_v4l.c
+++ b/drivers/media/usb/cpia2/cpia2_v4l.c
@@ -948,7 +948,7 @@ static int cpia2_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 	buf->sequence = cam->buffers[buf->index].seq;
 	buf->m.offset = cam->buffers[buf->index].data - cam->frame_buffer;
 	buf->length = cam->frame_size;
-	buf->reserved2 = 0;
+	buf->fence_fd = -1;
 	buf->reserved = 0;
 	memset(&buf->timecode, 0, sizeof(buf->timecode));
 
diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
index 821f2aa299ae..d624fb5df130 100644
--- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
+++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
@@ -370,7 +370,7 @@ struct v4l2_buffer32 {
 		__s32		fd;
 	} m;
 	__u32			length;
-	__u32			reserved2;
+	__s32			fence_fd;
 	__u32			reserved;
 };
 
@@ -533,8 +533,8 @@ static int put_v4l2_buffer32(struct v4l2_buffer *kp, struct v4l2_buffer32 __user
 		put_user(kp->timestamp.tv_usec, &up->timestamp.tv_usec) ||
 		copy_to_user(&up->timecode, &kp->timecode, sizeof(struct v4l2_timecode)) ||
 		put_user(kp->sequence, &up->sequence) ||
-		put_user(kp->reserved2, &up->reserved2) ||
 		put_user(kp->reserved, &up->reserved) ||
+		put_user(kp->fence_fd, &up->fence_fd) ||
 		put_user(kp->length, &up->length))
 			return -EFAULT;
 
diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
index 0c0669976bdc..110fb45fef6f 100644
--- a/drivers/media/v4l2-core/videobuf2-v4l2.c
+++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
@@ -203,7 +203,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, void *pb)
 	b->timestamp = ns_to_timeval(vb->timestamp);
 	b->timecode = vbuf->timecode;
 	b->sequence = vbuf->sequence;
-	b->reserved2 = 0;
+	b->fence_fd = -1;
 	b->reserved = 0;
 
 	if (q->is_multiplanar) {
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 185d6a0acc06..e5abab9a908c 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -924,7 +924,7 @@ struct v4l2_buffer {
 		__s32		fd;
 	} m;
 	__u32			length;
-	__u32			reserved2;
+	__s32			fence_fd;
 	__u32			reserved;
 };
 
@@ -961,6 +961,8 @@ struct v4l2_buffer {
 #define V4L2_BUF_FLAG_TSTAMP_SRC_SOE		0x00010000
 /* mem2mem encoder/decoder */
 #define V4L2_BUF_FLAG_LAST			0x00100000
+#define V4L2_BUF_FLAG_IN_FENCE			0x00200000
+#define V4L2_BUF_FLAG_OUT_FENCE			0x00400000
 
 /**
  * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
-- 
2.13.5

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#1728389 — [PATCH v3 13/15] [media] vb2: add infrastructure to support out-fences

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

Add vb2_setup_out_fence() and the needed members to struct vb2_buffer.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 55 ++++++++++++++++++++++++++++++++
 include/media/videobuf2-core.h           | 34 ++++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index bbbae0eed567..34adf1916194 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -23,8 +23,11 @@
 #include <linux/sched.h>
 #include <linux/freezer.h>
 #include <linux/kthread.h>
+#include <linux/sync_file.h>
+#include <linux/dma-fence.h>
 
 #include <media/videobuf2-core.h>
+#include <media/videobuf2-fence.h>
 #include <media/v4l2-mc.h>
 
 #include <trace/events/vb2.h>
@@ -1317,6 +1320,58 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
 }
 EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
 
+int vb2_setup_out_fence(struct vb2_queue *q)
+{
+	struct vb2_fence *fence;
+
+	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+	if (!fence)
+		return -ENOMEM;
+
+	fence->out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fence->out_fence_fd < 0) {
+		kfree(fence);
+		return fence->out_fence_fd;
+	}
+
+	fence->out_fence = vb2_fence_alloc();
+	if (!fence->out_fence)
+		goto err_fence;
+
+	fence->sync_file = sync_file_create(fence->out_fence);
+	if (!fence->sync_file) {
+		dma_fence_put(fence->out_fence);
+		goto err_fence;
+	}
+
+	spin_lock(&q->out_fence_lock);
+	list_add_tail(&fence->entry, &q->out_fence_list);
+	spin_unlock(&q->out_fence_lock);
+
+	return 0;
+
+err_fence:
+	kfree(fence);
+	put_unused_fd(fence->out_fence_fd);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(vb2_setup_out_fence);
+
+void vb2_cleanup_out_fence(struct vb2_queue *q)
+{
+	struct vb2_fence *fence;
+
+	spin_lock(&q->out_fence_lock);
+	fence = list_last_entry(&q->out_fence_list,
+				    struct vb2_fence, entry);
+	put_unused_fd(fence->out_fence_fd);
+	fput(fence->sync_file->file);
+	list_del(&fence->entry);
+	spin_unlock(&q->out_fence_lock);
+	kfree(fence);
+}
+EXPORT_SYMBOL_GPL(vb2_cleanup_out_fence);
+
 /**
  * vb2_start_streaming() - Attempt to start streaming.
  * @q:		videobuf2 queue
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 20099dc22f26..84e5e7216a1e 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -427,6 +427,24 @@ struct vb2_buf_ops {
 	void (*buffer_queued)(struct vb2_buffer *vb);
 };
 
+/*
+ * struct vb2_fence - storage for fence data before queueing to the driver.
+ *
+ * @out_fence_fd:	the fd where to install the sync_file
+ * @out_fence:		the fence associated to the sync_file
+ * @sync_file:		the sync_file to be shared with userspace via the
+ *			out_fence_fd
+ * @files:		stores files struct for cleanup purposes
+ * @entry:		the list head element for the out_fence_list
+ */
+struct vb2_fence {
+	int out_fence_fd;
+	struct dma_fence *out_fence;
+	struct sync_file *sync_file;
+	struct files_struct *files;
+	struct list_head entry;
+};
+
 /**
  * struct vb2_queue - a videobuf queue
  *
@@ -734,6 +752,22 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);
 
 /**
+ * vb2_setup_out_fence() - setup new out-fence
+ * @q:		The vb2_queue where to setup it
+ *
+ * Setup the file descriptor, the fence and the sync_file for the next
+ * buffer to be queued and add everything to the tail of the q->out_fence_list.
+ */
+int vb2_setup_out_fence(struct vb2_queue *q);
+
+/**
+ * vb2_cleanup_out_fence() - cleanup out-fence
+ * @q:		The vb2_queue to use for cleanup
+ *
+ * Clean up the last fence on the list. Used only when QBUF fails.
+ */
+void vb2_cleanup_out_fence(struct vb2_queue *q);
+/**
  * vb2_core_qbuf() - Queue a buffer from userspace
  *
  * @q:		videobuf2 queue
-- 
2.13.5

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