diff mbox

dma-buf/sync_file: de-stage sync_file

Message ID 1458310799-4446-2-git-send-email-gustavo@padovan.org (mailing list archive)
State New, archived
Headers show

Commit Message

Gustavo Padovan March 18, 2016, 2:19 p.m. UTC
From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

sync_file is useful to connect one or more fences to the file. The file is
used by userspace to track fences.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
---
 drivers/Kconfig                                    |   2 +
 drivers/dma-buf/Kconfig                            |  11 +
 drivers/dma-buf/Makefile                           |   1 +
 drivers/dma-buf/sync_file.c                        | 382 +++++++++++++++++++++
 drivers/staging/android/Kconfig                    |   1 +
 drivers/staging/android/sync.c                     | 362 -------------------
 drivers/staging/android/sync.h                     |  92 +----
 drivers/staging/android/sync_debug.c               |   1 +
 include/linux/sync_file.h                          | 106 ++++++
 .../uapi/sync.h => include/uapi/linux/sync_file.h  |   0
 10 files changed, 506 insertions(+), 452 deletions(-)
 create mode 100644 drivers/dma-buf/Kconfig
 create mode 100644 drivers/dma-buf/sync_file.c
 create mode 100644 include/linux/sync_file.h
 rename drivers/staging/android/uapi/sync.h => include/uapi/linux/sync_file.h (100%)

diff --git a/drivers/staging/android/uapi/sync.h b/include/uapi/linux/sync_file.h
similarity index 100%
rename from drivers/staging/android/uapi/sync.h
rename to include/uapi/linux/sync_file.h

Comments

Sumit Semwal March 21, 2016, 7:02 a.m. UTC | #1
Thanks for the patch, Gustavo!

On 18 March 2016 at 19:49, Gustavo Padovan <gustavo@padovan.org> wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>
> sync_file is useful to connect one or more fences to the file. The file is
> used by userspace to track fences.
>
I think it is worthwhile to add relevant bits to the Documentation as
well - care to add relevant stuff to either Documentation/dma_buf.txt,
or to a file of its own? (I'd prefer the former, but would leave it
upto you.)

> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> ---
>  drivers/Kconfig                                    |   2 +
>  drivers/dma-buf/Kconfig                            |  11 +
>  drivers/dma-buf/Makefile                           |   1 +
>  drivers/dma-buf/sync_file.c                        | 382 +++++++++++++++++++++
>  drivers/staging/android/Kconfig                    |   1 +
>  drivers/staging/android/sync.c                     | 362 -------------------
>  drivers/staging/android/sync.h                     |  92 +----
>  drivers/staging/android/sync_debug.c               |   1 +
>  include/linux/sync_file.h                          | 106 ++++++
>  .../uapi/sync.h => include/uapi/linux/sync_file.h  |   0
>  10 files changed, 506 insertions(+), 452 deletions(-)
>  create mode 100644 drivers/dma-buf/Kconfig
>  create mode 100644 drivers/dma-buf/sync_file.c
>  create mode 100644 include/linux/sync_file.h
>  rename drivers/staging/android/uapi/sync.h => include/uapi/linux/sync_file.h (100%)
>
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index d2ac339..430f761 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -114,6 +114,8 @@ source "drivers/rtc/Kconfig"
>
>  source "drivers/dma/Kconfig"
>
> +source "drivers/dma-buf/Kconfig"
> +
>  source "drivers/dca/Kconfig"
>
>  source "drivers/auxdisplay/Kconfig"
> diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
> new file mode 100644
> index 0000000..9824bc4
> --- /dev/null
> +++ b/drivers/dma-buf/Kconfig
> @@ -0,0 +1,11 @@
> +menu "DMABUF options"
> +
> +config SYNC_FILE
> +       bool "sync_file support for fences"
> +       default n
> +       select ANON_INODES
> +       select DMA_SHARED_BUFFER
> +       ---help---
> +         This option enables the fence framework synchronization to export
> +         sync_files to userspace that can represent one or more fences.
> +endmenu
> diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> index 57a675f..4a424ec 100644
> --- a/drivers/dma-buf/Makefile
> +++ b/drivers/dma-buf/Makefile
> @@ -1 +1,2 @@
>  obj-y := dma-buf.o fence.o reservation.o seqno-fence.o
> +obj-$(CONFIG_SYNC_FILE)                += sync_file.o
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> new file mode 100644
> index 0000000..df786a2
> --- /dev/null
> +++ b/drivers/dma-buf/sync_file.c
> @@ -0,0 +1,382 @@
> +/*
> + * drivers/dma-buf/sync_file.c
> + *
> + * Copyright (C) 2012 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/export.h>
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/kernel.h>
> +#include <linux/poll.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/sync_file.h>
> +#include <uapi/linux/sync_file.h>
> +
> +static const struct file_operations sync_file_fops;
> +
> +static struct sync_file *sync_file_alloc(int size, const char *name)
> +{
> +       struct sync_file *sync_file;
> +
> +       sync_file = kzalloc(size, GFP_KERNEL);
> +       if (!sync_file)
> +               return NULL;
> +
> +       sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
> +                                            sync_file, 0);
> +       if (IS_ERR(sync_file->file))
> +               goto err;
> +
> +       kref_init(&sync_file->kref);
> +       strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +
> +       init_waitqueue_head(&sync_file->wq);
> +
> +       return sync_file;
> +
> +err:
> +       kfree(sync_file);
> +       return NULL;
> +}
> +
> +static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
> +{
> +       struct sync_file_cb *check;
> +       struct sync_file *sync_file;
> +
> +       check = container_of(cb, struct sync_file_cb, cb);
> +       sync_file = check->sync_file;
> +
> +       if (atomic_dec_and_test(&sync_file->status))
> +               wake_up_all(&sync_file->wq);
> +}
> +
> +/* TODO: implement a create which takes more that one fence */
> +struct sync_file *sync_file_create(const char *name, struct fence *fence)
> +{
> +       struct sync_file *sync_file;
> +
> +       sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]),
> +                                   name);
> +       if (!sync_file)
> +               return NULL;
> +
> +       sync_file->num_fences = 1;
> +       atomic_set(&sync_file->status, 1);
> +
> +       sync_file->cbs[0].fence = fence;
> +       sync_file->cbs[0].sync_file = sync_file;
> +       if (fence_add_callback(fence, &sync_file->cbs[0].cb,
> +                              fence_check_cb_func))
> +               atomic_dec(&sync_file->status);
> +
> +       return sync_file;
> +}
> +EXPORT_SYMBOL(sync_file_create);
> +
> +struct sync_file *sync_file_fdget(int fd)
> +{
> +       struct file *file = fget(fd);
> +
> +       if (!file)
> +               return NULL;
> +
> +       if (file->f_op != &sync_file_fops)
> +               goto err;
> +
> +       return file->private_data;
> +
> +err:
> +       fput(file);
> +       return NULL;
> +}
> +EXPORT_SYMBOL(sync_file_fdget);
> +
> +void sync_file_put(struct sync_file *sync_file)
> +{
> +       fput(sync_file->file);
> +}
> +EXPORT_SYMBOL(sync_file_put);
> +
> +void sync_file_install(struct sync_file *sync_file, int fd)
> +{
> +       fd_install(fd, sync_file->file);
> +}
> +EXPORT_SYMBOL(sync_file_install);
> +
> +static void sync_file_add_pt(struct sync_file *sync_file, int *i,
> +                            struct fence *fence)
> +{
> +       sync_file->cbs[*i].fence = fence;
> +       sync_file->cbs[*i].sync_file = sync_file;
> +
> +       if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
> +                               fence_check_cb_func)) {
> +               fence_get(fence);
> +               (*i)++;
> +       }
> +}
> +
> +struct sync_file *sync_file_merge(const char *name,
> +                                 struct sync_file *a, struct sync_file *b)
> +{
> +       int num_fences = a->num_fences + b->num_fences;
> +       struct sync_file *sync_file;
> +       int i, i_a, i_b;
> +       unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
> +
> +       sync_file = sync_file_alloc(size, name);
> +       if (!sync_file)
> +               return NULL;
> +
> +       atomic_set(&sync_file->status, num_fences);
> +
> +       /*
> +        * Assume sync_file a and b are both ordered and have no
> +        * duplicates with the same context.
> +        *
> +        * If a sync_file can only be created with sync_file_merge
> +        * and sync_file_create, this is a reasonable assumption.
> +        */
> +       for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
> +               struct fence *pt_a = a->cbs[i_a].fence;
> +               struct fence *pt_b = b->cbs[i_b].fence;
> +
> +               if (pt_a->context < pt_b->context) {
> +                       sync_file_add_pt(sync_file, &i, pt_a);
> +
> +                       i_a++;
> +               } else if (pt_a->context > pt_b->context) {
> +                       sync_file_add_pt(sync_file, &i, pt_b);
> +
> +                       i_b++;
> +               } else {
> +                       if (pt_a->seqno - pt_b->seqno <= INT_MAX)
> +                               sync_file_add_pt(sync_file, &i, pt_a);
> +                       else
> +                               sync_file_add_pt(sync_file, &i, pt_b);
> +
> +                       i_a++;
> +                       i_b++;
> +               }
> +       }
> +
> +       for (; i_a < a->num_fences; i_a++)
> +               sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
> +
> +       for (; i_b < b->num_fences; i_b++)
> +               sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
> +
> +       if (num_fences > i)
> +               atomic_sub(num_fences - i, &sync_file->status);
> +       sync_file->num_fences = i;
> +
> +       return sync_file;
> +}
> +EXPORT_SYMBOL(sync_file_merge);
> +
> +static void sync_file_free(struct kref *kref)
> +{
> +       struct sync_file *sync_file = container_of(kref, struct sync_file,
> +                                                    kref);
> +       int i;
> +
> +       for (i = 0; i < sync_file->num_fences; ++i) {
> +               fence_remove_callback(sync_file->cbs[i].fence,
> +                                     &sync_file->cbs[i].cb);
> +               fence_put(sync_file->cbs[i].fence);
> +       }
> +
> +       kfree(sync_file);
> +}
> +
> +static int sync_file_release(struct inode *inode, struct file *file)
> +{
> +       struct sync_file *sync_file = file->private_data;
> +
> +       kref_put(&sync_file->kref, sync_file_free);
> +       return 0;
> +}
> +
> +static unsigned int sync_file_poll(struct file *file, poll_table *wait)
> +{
> +       struct sync_file *sync_file = file->private_data;
> +       int status;
> +
> +       poll_wait(file, &sync_file->wq, wait);
> +
> +       status = atomic_read(&sync_file->status);
> +
> +       if (!status)
> +               return POLLIN;
> +       if (status < 0)
> +               return POLLERR;
> +       return 0;
> +}
> +
> +static long sync_file_ioctl_merge(struct sync_file *sync_file,
> +                                  unsigned long arg)
> +{
> +       int fd = get_unused_fd_flags(O_CLOEXEC);
> +       int err;
> +       struct sync_file *fence2, *fence3;
> +       struct sync_merge_data data;
> +
> +       if (fd < 0)
> +               return fd;
> +
> +       if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
> +               err = -EFAULT;
> +               goto err_put_fd;
> +       }
> +
> +       if (data.flags || data.pad) {
> +               err = -EINVAL;
> +               goto err_put_fd;
> +       }
> +
> +       fence2 = sync_file_fdget(data.fd2);
> +       if (!fence2) {
> +               err = -ENOENT;
> +               goto err_put_fd;
> +       }
> +
> +       data.name[sizeof(data.name) - 1] = '\0';
> +       fence3 = sync_file_merge(data.name, sync_file, fence2);
> +       if (!fence3) {
> +               err = -ENOMEM;
> +               goto err_put_fence2;
> +       }
> +
> +       data.fence = fd;
> +       if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
> +               err = -EFAULT;
> +               goto err_put_fence3;
> +       }
> +
> +       sync_file_install(fence3, fd);
> +       sync_file_put(fence2);
> +       return 0;
> +
> +err_put_fence3:
> +       sync_file_put(fence3);
> +
> +err_put_fence2:
> +       sync_file_put(fence2);
> +
> +err_put_fd:
> +       put_unused_fd(fd);
> +       return err;
> +}
> +
> +static void sync_fill_fence_info(struct fence *fence,
> +                               struct sync_fence_info *info)
> +{
> +       strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
> +               sizeof(info->obj_name));
> +       strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
> +               sizeof(info->driver_name));
> +       if (fence_is_signaled(fence))
> +               info->status = fence->status >= 0 ? 1 : fence->status;
> +       else
> +               info->status = 0;
> +       info->timestamp_ns = ktime_to_ns(fence->timestamp);
> +}
> +
> +static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> +                                       unsigned long arg)
> +{
> +       struct sync_file_info info;
> +       struct sync_fence_info *fence_info = NULL;
> +       __u32 size;
> +       int ret, i;
> +
> +       if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
> +               return -EFAULT;
> +
> +       if (info.flags || info.pad)
> +               return -EINVAL;
> +
> +       /*
> +        * Passing num_fences = 0 means that userspace doesn't want to
> +        * retrieve any sync_fence_info. If num_fences = 0 we skip filling
> +        * sync_fence_info and return the actual number of fences on
> +        * info->num_fences.
> +        */
> +       if (!info.num_fences)
> +               goto no_fences;
> +
> +       if (info.num_fences < sync_file->num_fences)
> +               return -EINVAL;
> +
> +       size = sync_file->num_fences * sizeof(*fence_info);
> +       fence_info = kzalloc(size, GFP_KERNEL);
> +       if (!fence_info)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < sync_file->num_fences; ++i)
> +               sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
> +
> +       if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
> +                        size)) {
> +               ret = -EFAULT;
> +               goto out;
> +       }
> +
> +no_fences:
> +       strlcpy(info.name, sync_file->name, sizeof(info.name));
> +       info.status = atomic_read(&sync_file->status);
> +       if (info.status >= 0)
> +               info.status = !info.status;
> +
> +       info.num_fences = sync_file->num_fences;
> +
> +       if (copy_to_user((void __user *)arg, &info, sizeof(info)))
> +               ret = -EFAULT;
> +       else
> +               ret = 0;
> +
> +out:
> +       kfree(fence_info);
> +
> +       return ret;
> +}
> +
> +static long sync_file_ioctl(struct file *file, unsigned int cmd,
> +                            unsigned long arg)
> +{
> +       struct sync_file *sync_file = file->private_data;
> +
> +       switch (cmd) {
> +       case SYNC_IOC_MERGE:
> +               return sync_file_ioctl_merge(sync_file, arg);
> +
> +       case SYNC_IOC_FILE_INFO:
> +               return sync_file_ioctl_fence_info(sync_file, arg);
> +
> +       default:
> +               return -ENOTTY;
> +       }
> +}
> +
> +static const struct file_operations sync_file_fops = {
> +       .release = sync_file_release,
> +       .poll = sync_file_poll,
> +       .unlocked_ioctl = sync_file_ioctl,
> +       .compat_ioctl = sync_file_ioctl,
> +};
> +
> diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
> index bd90d20..2756988 100644
> --- a/drivers/staging/android/Kconfig
> +++ b/drivers/staging/android/Kconfig
> @@ -52,6 +52,7 @@ config SW_SYNC
>         bool "Software synchronization objects"
>         default n
>         depends on SYNC
> +       depends on SYNC_FILE
>         ---help---
>           A sync object driver that uses a 32bit counter to coordinate
>           synchronization.  Useful when there is no hardware primitive backing
> diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
> index f9c6094..1d14c83 100644
> --- a/drivers/staging/android/sync.c
> +++ b/drivers/staging/android/sync.c
> @@ -16,10 +16,7 @@
>
>  #include <linux/debugfs.h>
>  #include <linux/export.h>
> -#include <linux/file.h>
> -#include <linux/fs.h>
>  #include <linux/kernel.h>
> -#include <linux/poll.h>
>  #include <linux/sched.h>
>  #include <linux/seq_file.h>
>  #include <linux/slab.h>
> @@ -32,7 +29,6 @@
>  #include "trace/sync.h"
>
>  static const struct fence_ops android_fence_ops;
> -static const struct file_operations sync_file_fops;
>
>  struct sync_timeline *sync_timeline_create(const struct sync_timeline_ops *ops,
>                                            int size, const char *name)
> @@ -136,170 +132,6 @@ struct fence *sync_pt_create(struct sync_timeline *obj, int size)
>  }
>  EXPORT_SYMBOL(sync_pt_create);
>
> -static struct sync_file *sync_file_alloc(int size, const char *name)
> -{
> -       struct sync_file *sync_file;
> -
> -       sync_file = kzalloc(size, GFP_KERNEL);
> -       if (!sync_file)
> -               return NULL;
> -
> -       sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
> -                                            sync_file, 0);
> -       if (IS_ERR(sync_file->file))
> -               goto err;
> -
> -       kref_init(&sync_file->kref);
> -       strlcpy(sync_file->name, name, sizeof(sync_file->name));
> -
> -       init_waitqueue_head(&sync_file->wq);
> -
> -       return sync_file;
> -
> -err:
> -       kfree(sync_file);
> -       return NULL;
> -}
> -
> -static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
> -{
> -       struct sync_file_cb *check;
> -       struct sync_file *sync_file;
> -
> -       check = container_of(cb, struct sync_file_cb, cb);
> -       sync_file = check->sync_file;
> -
> -       if (atomic_dec_and_test(&sync_file->status))
> -               wake_up_all(&sync_file->wq);
> -}
> -
> -/* TODO: implement a create which takes more that one fence */
> -struct sync_file *sync_file_create(const char *name, struct fence *fence)
> -{
> -       struct sync_file *sync_file;
> -
> -       sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]),
> -                                   name);
> -       if (!sync_file)
> -               return NULL;
> -
> -       sync_file->num_fences = 1;
> -       atomic_set(&sync_file->status, 1);
> -
> -       sync_file->cbs[0].fence = fence;
> -       sync_file->cbs[0].sync_file = sync_file;
> -       if (fence_add_callback(fence, &sync_file->cbs[0].cb,
> -                              fence_check_cb_func))
> -               atomic_dec(&sync_file->status);
> -
> -       sync_file_debug_add(sync_file);
> -
> -       return sync_file;
> -}
> -EXPORT_SYMBOL(sync_file_create);
> -
> -struct sync_file *sync_file_fdget(int fd)
> -{
> -       struct file *file = fget(fd);
> -
> -       if (!file)
> -               return NULL;
> -
> -       if (file->f_op != &sync_file_fops)
> -               goto err;
> -
> -       return file->private_data;
> -
> -err:
> -       fput(file);
> -       return NULL;
> -}
> -EXPORT_SYMBOL(sync_file_fdget);
> -
> -void sync_file_put(struct sync_file *sync_file)
> -{
> -       fput(sync_file->file);
> -}
> -EXPORT_SYMBOL(sync_file_put);
> -
> -void sync_file_install(struct sync_file *sync_file, int fd)
> -{
> -       fd_install(fd, sync_file->file);
> -}
> -EXPORT_SYMBOL(sync_file_install);
> -
> -static void sync_file_add_pt(struct sync_file *sync_file, int *i,
> -                            struct fence *fence)
> -{
> -       sync_file->cbs[*i].fence = fence;
> -       sync_file->cbs[*i].sync_file = sync_file;
> -
> -       if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
> -                               fence_check_cb_func)) {
> -               fence_get(fence);
> -               (*i)++;
> -       }
> -}
> -
> -struct sync_file *sync_file_merge(const char *name,
> -                                 struct sync_file *a, struct sync_file *b)
> -{
> -       int num_fences = a->num_fences + b->num_fences;
> -       struct sync_file *sync_file;
> -       int i, i_a, i_b;
> -       unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
> -
> -       sync_file = sync_file_alloc(size, name);
> -       if (!sync_file)
> -               return NULL;
> -
> -       atomic_set(&sync_file->status, num_fences);
> -
> -       /*
> -        * Assume sync_file a and b are both ordered and have no
> -        * duplicates with the same context.
> -        *
> -        * If a sync_file can only be created with sync_file_merge
> -        * and sync_file_create, this is a reasonable assumption.
> -        */
> -       for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
> -               struct fence *pt_a = a->cbs[i_a].fence;
> -               struct fence *pt_b = b->cbs[i_b].fence;
> -
> -               if (pt_a->context < pt_b->context) {
> -                       sync_file_add_pt(sync_file, &i, pt_a);
> -
> -                       i_a++;
> -               } else if (pt_a->context > pt_b->context) {
> -                       sync_file_add_pt(sync_file, &i, pt_b);
> -
> -                       i_b++;
> -               } else {
> -                       if (pt_a->seqno - pt_b->seqno <= INT_MAX)
> -                               sync_file_add_pt(sync_file, &i, pt_a);
> -                       else
> -                               sync_file_add_pt(sync_file, &i, pt_b);
> -
> -                       i_a++;
> -                       i_b++;
> -               }
> -       }
> -
> -       for (; i_a < a->num_fences; i_a++)
> -               sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
> -
> -       for (; i_b < b->num_fences; i_b++)
> -               sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
> -
> -       if (num_fences > i)
> -               atomic_sub(num_fences - i, &sync_file->status);
> -       sync_file->num_fences = i;
> -
> -       sync_file_debug_add(sync_file);
> -       return sync_file;
> -}
> -EXPORT_SYMBOL(sync_file_merge);
> -
>  static const char *android_fence_get_driver_name(struct fence *fence)
>  {
>         struct sync_timeline *parent = fence_parent(fence);
> @@ -387,197 +219,3 @@ static const struct fence_ops android_fence_ops = {
>         .fence_value_str = android_fence_value_str,
>         .timeline_value_str = android_fence_timeline_value_str,
>  };
> -
> -static void sync_file_free(struct kref *kref)
> -{
> -       struct sync_file *sync_file = container_of(kref, struct sync_file,
> -                                                    kref);
> -       int i;
> -
> -       for (i = 0; i < sync_file->num_fences; ++i) {
> -               fence_remove_callback(sync_file->cbs[i].fence,
> -                                     &sync_file->cbs[i].cb);
> -               fence_put(sync_file->cbs[i].fence);
> -       }
> -
> -       kfree(sync_file);
> -}
> -
> -static int sync_file_release(struct inode *inode, struct file *file)
> -{
> -       struct sync_file *sync_file = file->private_data;
> -
> -       sync_file_debug_remove(sync_file);
> -
> -       kref_put(&sync_file->kref, sync_file_free);
> -       return 0;
> -}
> -
> -static unsigned int sync_file_poll(struct file *file, poll_table *wait)
> -{
> -       struct sync_file *sync_file = file->private_data;
> -       int status;
> -
> -       poll_wait(file, &sync_file->wq, wait);
> -
> -       status = atomic_read(&sync_file->status);
> -
> -       if (!status)
> -               return POLLIN;
> -       if (status < 0)
> -               return POLLERR;
> -       return 0;
> -}
> -
> -static long sync_file_ioctl_merge(struct sync_file *sync_file,
> -                                  unsigned long arg)
> -{
> -       int fd = get_unused_fd_flags(O_CLOEXEC);
> -       int err;
> -       struct sync_file *fence2, *fence3;
> -       struct sync_merge_data data;
> -
> -       if (fd < 0)
> -               return fd;
> -
> -       if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
> -               err = -EFAULT;
> -               goto err_put_fd;
> -       }
> -
> -       if (data.flags || data.pad) {
> -               err = -EINVAL;
> -               goto err_put_fd;
> -       }
> -
> -       fence2 = sync_file_fdget(data.fd2);
> -       if (!fence2) {
> -               err = -ENOENT;
> -               goto err_put_fd;
> -       }
> -
> -       data.name[sizeof(data.name) - 1] = '\0';
> -       fence3 = sync_file_merge(data.name, sync_file, fence2);
> -       if (!fence3) {
> -               err = -ENOMEM;
> -               goto err_put_fence2;
> -       }
> -
> -       data.fence = fd;
> -       if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
> -               err = -EFAULT;
> -               goto err_put_fence3;
> -       }
> -
> -       sync_file_install(fence3, fd);
> -       sync_file_put(fence2);
> -       return 0;
> -
> -err_put_fence3:
> -       sync_file_put(fence3);
> -
> -err_put_fence2:
> -       sync_file_put(fence2);
> -
> -err_put_fd:
> -       put_unused_fd(fd);
> -       return err;
> -}
> -
> -static void sync_fill_fence_info(struct fence *fence,
> -                               struct sync_fence_info *info)
> -{
> -       strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
> -               sizeof(info->obj_name));
> -       strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
> -               sizeof(info->driver_name));
> -       if (fence_is_signaled(fence))
> -               info->status = fence->status >= 0 ? 1 : fence->status;
> -       else
> -               info->status = 0;
> -       info->timestamp_ns = ktime_to_ns(fence->timestamp);
> -}
> -
> -static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> -                                       unsigned long arg)
> -{
> -       struct sync_file_info info;
> -       struct sync_fence_info *fence_info = NULL;
> -       __u32 size;
> -       int ret, i;
> -
> -       if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
> -               return -EFAULT;
> -
> -       if (info.flags || info.pad)
> -               return -EINVAL;
> -
> -       /*
> -        * Passing num_fences = 0 means that userspace doesn't want to
> -        * retrieve any sync_fence_info. If num_fences = 0 we skip filling
> -        * sync_fence_info and return the actual number of fences on
> -        * info->num_fences.
> -        */
> -       if (!info.num_fences)
> -               goto no_fences;
> -
> -       if (info.num_fences < sync_file->num_fences)
> -               return -EINVAL;
> -
> -       size = sync_file->num_fences * sizeof(*fence_info);
> -       fence_info = kzalloc(size, GFP_KERNEL);
> -       if (!fence_info)
> -               return -ENOMEM;
> -
> -       for (i = 0; i < sync_file->num_fences; ++i)
> -               sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
> -
> -       if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
> -                        size)) {
> -               ret = -EFAULT;
> -               goto out;
> -       }
> -
> -no_fences:
> -       strlcpy(info.name, sync_file->name, sizeof(info.name));
> -       info.status = atomic_read(&sync_file->status);
> -       if (info.status >= 0)
> -               info.status = !info.status;
> -
> -       info.num_fences = sync_file->num_fences;
> -
> -       if (copy_to_user((void __user *)arg, &info, sizeof(info)))
> -               ret = -EFAULT;
> -       else
> -               ret = 0;
> -
> -out:
> -       kfree(fence_info);
> -
> -       return ret;
> -}
> -
> -static long sync_file_ioctl(struct file *file, unsigned int cmd,
> -                            unsigned long arg)
> -{
> -       struct sync_file *sync_file = file->private_data;
> -
> -       switch (cmd) {
> -       case SYNC_IOC_MERGE:
> -               return sync_file_ioctl_merge(sync_file, arg);
> -
> -       case SYNC_IOC_FILE_INFO:
> -               return sync_file_ioctl_fence_info(sync_file, arg);
> -
> -       default:
> -               return -ENOTTY;
> -       }
> -}
> -
> -static const struct file_operations sync_file_fops = {
> -       .release = sync_file_release,
> -       .poll = sync_file_poll,
> -       .unlocked_ioctl = sync_file_ioctl,
> -       .compat_ioctl = sync_file_ioctl,
> -};
> -
> diff --git a/drivers/staging/android/sync.h b/drivers/staging/android/sync.h
> index d2a1734..97574be 100644
> --- a/drivers/staging/android/sync.h
> +++ b/drivers/staging/android/sync.h
> @@ -19,11 +19,10 @@
>  #include <linux/list.h>
>  #include <linux/spinlock.h>
>  #include <linux/fence.h>
> -
> -#include "uapi/sync.h"
> +#include <linux/sync_file.h>
> +#include <uapi/linux/sync_file.h>
>
>  struct sync_timeline;
> -struct sync_file;
>
>  /**
>   * struct sync_timeline_ops - sync object implementation ops
> @@ -86,38 +85,6 @@ static inline struct sync_timeline *fence_parent(struct fence *fence)
>                             child_list_lock);
>  }
>
> -struct sync_file_cb {
> -       struct fence_cb cb;
> -       struct fence *fence;
> -       struct sync_file *sync_file;
> -};
> -
> -/**
> - * struct sync_file - sync file to export to the userspace
> - * @file:              file representing this fence
> - * @kref:              reference count on fence.
> - * @name:              name of sync_file.  Useful for debugging
> - * @sync_file_list:    membership in global file list
> - * @num_fences         number of sync_pts in the fence
> - * @wq:                        wait queue for fence signaling
> - * @status:            0: signaled, >0:active, <0: error
> - * @cbs:               sync_pts callback information
> - */
> -struct sync_file {
> -       struct file             *file;
> -       struct kref             kref;
> -       char                    name[32];
> -#ifdef CONFIG_DEBUG_FS
> -       struct list_head        sync_file_list;
> -#endif
> -       int num_fences;
> -
> -       wait_queue_head_t       wq;
> -       atomic_t                status;
> -
> -       struct sync_file_cb     cbs[];
> -};
> -
>  /*
>   * API for sync_timeline implementers
>   */
> @@ -167,61 +134,6 @@ void sync_timeline_signal(struct sync_timeline *obj);
>   */
>  struct fence *sync_pt_create(struct sync_timeline *parent, int size);
>
> -/**
> - * sync_fence_create() - creates a sync fence
> - * @name:      name of fence to create
> - * @fence:     fence to add to the sync_fence
> - *
> - * Creates a sync_file containg @fence. Once this is called, the sync_file
> - * takes ownership of @fence.
> - */
> -struct sync_file *sync_file_create(const char *name, struct fence *fence);
> -
> -/*
> - * API for sync_file consumers
> - */
> -
> -/**
> - * sync_file_merge() - merge two sync_files
> - * @name:      name of new fence
> - * @a:         sync_file a
> - * @b:         sync_file b
> - *
> - * Creates a new sync_file which contains copies of all the fences in both
> - * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
> - * new merged sync_file or NULL in case of error.
> - */
> -struct sync_file *sync_file_merge(const char *name,
> -                                   struct sync_file *a, struct sync_file *b);
> -
> -/**
> - * sync_file_fdget() - get a sync_file from an fd
> - * @fd:                fd referencing a fence
> - *
> - * Ensures @fd references a valid sync_file, increments the refcount of the
> - * backing file. Returns the sync_file or NULL in case of error.
> - */
> -struct sync_file *sync_file_fdget(int fd);
> -
> -/**
> - * sync_file_put() - puts a reference of a sync_file
> - * @sync_file: sync_file to put
> - *
> - * Puts a reference on @sync_fence.  If this is the last reference, the
> - * sync_fil and all it's sync_pts will be freed
> - */
> -void sync_file_put(struct sync_file *sync_file);
> -
> -/**
> - * sync_file_install() - installs a sync_file into a file descriptor
> - * @sync_file: sync_file to install
> - * @fd:                file descriptor in which to install the fence
> - *
> - * Installs @sync_file into @fd.  @fd's should be acquired through
> - * get_unused_fd_flags(O_CLOEXEC).
> - */
> -void sync_file_install(struct sync_file *sync_file, int fd);
> -
>  #ifdef CONFIG_DEBUG_FS
>
>  void sync_timeline_debug_add(struct sync_timeline *obj);
> diff --git a/drivers/staging/android/sync_debug.c b/drivers/staging/android/sync_debug.c
> index 5a7ec58..e5b14f0 100644
> --- a/drivers/staging/android/sync_debug.c
> +++ b/drivers/staging/android/sync_debug.c
> @@ -26,6 +26,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/anon_inodes.h>
>  #include <linux/time64.h>
> +#include <linux/sync_file.h>
>  #include "sw_sync.h"
>
>  #ifdef CONFIG_DEBUG_FS
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> new file mode 100644
> index 0000000..7b7a89d
> --- /dev/null
> +++ b/include/linux/sync_file.h
> @@ -0,0 +1,106 @@
> +/*
> + * include/linux/sync_file.h
> + *
> + * Copyright (C) 2012 Google, Inc.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#ifndef _LINUX_SYNC_FILE_H
> +#define _LINUX_SYNC_FILE_H
> +
> +#include <linux/types.h>
> +#include <linux/kref.h>
> +#include <linux/ktime.h>
> +#include <linux/list.h>
> +#include <linux/spinlock.h>
> +#include <linux/fence.h>
> +
> +struct sync_file_cb {
> +       struct fence_cb cb;
> +       struct fence *fence;
> +       struct sync_file *sync_file;
> +};
> +
> +/**
> + * struct sync_file - sync file to export to the userspace
> + * @file:              file representing this fence
> + * @kref:              reference count on fence.
> + * @name:              name of sync_file.  Useful for debugging
> + * @sync_file_list:    membership in global file list
> + * @num_fences         number of sync_pts in the fence
> + * @wq:                        wait queue for fence signaling
> + * @status:            0: signaled, >0:active, <0: error
> + * @cbs:               sync_pts callback information
> + */
> +struct sync_file {
> +       struct file             *file;
> +       struct kref             kref;
> +       char                    name[32];
> +#ifdef CONFIG_DEBUG_FS
> +       struct list_head        sync_file_list;
> +#endif
> +       int num_fences;
> +
> +       wait_queue_head_t       wq;
> +       atomic_t                status;
> +
> +       struct sync_file_cb     cbs[];
> +};
> +
> +/**
> + * sync_file_create() - creates a sync file
> + * @name:      name of fence to create
> + * @fence:     fence to add to the sync_file
> + *
> + * Creates a sync_file containg @fence. Once this is called, the sync_file
> + * takes ownership of @fence.
> + */
> +struct sync_file *sync_file_create(const char *name, struct fence *fence);
> +
> +/**
> + * sync_file_merge() - merge two sync_files
> + * @name:      name of new fence
> + * @a:         sync_file a
> + * @b:         sync_file b
> + *
> + * Creates a new sync_file which contains copies of all the fences in both
> + * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
> + * new merged sync_file or NULL in case of error.
> + */
> +struct sync_file *sync_file_merge(const char *name,
> +                                   struct sync_file *a, struct sync_file *b);
> +
> +/**
> + * sync_file_fdget() - get a sync_file from an fd
> + * @fd:                fd referencing a fence
> + *
> + * Ensures @fd references a valid sync_file, increments the refcount of the
> + * backing file. Returns the sync_file or NULL in case of error.
> + */
> +struct sync_file *sync_file_fdget(int fd);
> +
> +/**
> + * sync_file_put() - puts a reference of a sync_file
> + * @sync_file: sync_file to put
> + *
> + * Puts a reference on @sync_fence.  If this is the last reference, the
> + * sync_fil and all it's sync_pts will be freed
> + */
> +void sync_file_put(struct sync_file *sync_file);
> +
> +/**
> + * sync_file_install() - installs a sync_file into a file descriptor
> + * @sync_file: sync_file to install
> + * @fd:                file descriptor in which to install the fence
> + *
> + * Installs @sync_file into @fd.  @fd's should be acquired through
> + * get_unused_fd_flags(O_CLOEXEC).
> + */
> +void sync_file_install(struct sync_file *sync_file, int fd);
> +
> +#endif /* _LINUX_SYNC_H */
> diff --git a/drivers/staging/android/uapi/sync.h b/include/uapi/linux/sync_file.h
> similarity index 100%
> rename from drivers/staging/android/uapi/sync.h
> rename to include/uapi/linux/sync_file.h
> --
> 2.5.0
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Best,
Sumit.
Gustavo Padovan March 23, 2016, 2:59 p.m. UTC | #2
Hi Sumit,

2016-03-21 Sumit Semwal <sumit.semwal@linaro.org>:

> Thanks for the patch, Gustavo!
> 
> On 18 March 2016 at 19:49, Gustavo Padovan <gustavo@padovan.org> wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> >
> > sync_file is useful to connect one or more fences to the file. The file is
> > used by userspace to track fences.
> >
> I think it is worthwhile to add relevant bits to the Documentation as
> well - care to add relevant stuff to either Documentation/dma_buf.txt,
> or to a file of its own? (I'd prefer the former, but would leave it
> upto you.)

Sure, that is part of my plan. I'm currently trying to have a working
version of fences on DRM then I think I'll be able to add Documentation
for everything I have done.

	Gustavo
diff mbox

Patch

diff --git a/drivers/Kconfig b/drivers/Kconfig
index d2ac339..430f761 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -114,6 +114,8 @@  source "drivers/rtc/Kconfig"
 
 source "drivers/dma/Kconfig"
 
+source "drivers/dma-buf/Kconfig"
+
 source "drivers/dca/Kconfig"
 
 source "drivers/auxdisplay/Kconfig"
diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
new file mode 100644
index 0000000..9824bc4
--- /dev/null
+++ b/drivers/dma-buf/Kconfig
@@ -0,0 +1,11 @@ 
+menu "DMABUF options"
+
+config SYNC_FILE
+	bool "sync_file support for fences"
+	default n
+	select ANON_INODES
+	select DMA_SHARED_BUFFER
+	---help---
+	  This option enables the fence framework synchronization to export
+	  sync_files to userspace that can represent one or more fences.
+endmenu
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 57a675f..4a424ec 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -1 +1,2 @@ 
 obj-y := dma-buf.o fence.o reservation.o seqno-fence.o
+obj-$(CONFIG_SYNC_FILE)		+= sync_file.o
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
new file mode 100644
index 0000000..df786a2
--- /dev/null
+++ b/drivers/dma-buf/sync_file.c
@@ -0,0 +1,382 @@ 
+/*
+ * drivers/dma-buf/sync_file.c
+ *
+ * Copyright (C) 2012 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/anon_inodes.h>
+#include <linux/sync_file.h>
+#include <uapi/linux/sync_file.h>
+
+static const struct file_operations sync_file_fops;
+
+static struct sync_file *sync_file_alloc(int size, const char *name)
+{
+	struct sync_file *sync_file;
+
+	sync_file = kzalloc(size, GFP_KERNEL);
+	if (!sync_file)
+		return NULL;
+
+	sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
+					     sync_file, 0);
+	if (IS_ERR(sync_file->file))
+		goto err;
+
+	kref_init(&sync_file->kref);
+	strlcpy(sync_file->name, name, sizeof(sync_file->name));
+
+	init_waitqueue_head(&sync_file->wq);
+
+	return sync_file;
+
+err:
+	kfree(sync_file);
+	return NULL;
+}
+
+static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
+{
+	struct sync_file_cb *check;
+	struct sync_file *sync_file;
+
+	check = container_of(cb, struct sync_file_cb, cb);
+	sync_file = check->sync_file;
+
+	if (atomic_dec_and_test(&sync_file->status))
+		wake_up_all(&sync_file->wq);
+}
+
+/* TODO: implement a create which takes more that one fence */
+struct sync_file *sync_file_create(const char *name, struct fence *fence)
+{
+	struct sync_file *sync_file;
+
+	sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]),
+				    name);
+	if (!sync_file)
+		return NULL;
+
+	sync_file->num_fences = 1;
+	atomic_set(&sync_file->status, 1);
+
+	sync_file->cbs[0].fence = fence;
+	sync_file->cbs[0].sync_file = sync_file;
+	if (fence_add_callback(fence, &sync_file->cbs[0].cb,
+			       fence_check_cb_func))
+		atomic_dec(&sync_file->status);
+
+	return sync_file;
+}
+EXPORT_SYMBOL(sync_file_create);
+
+struct sync_file *sync_file_fdget(int fd)
+{
+	struct file *file = fget(fd);
+
+	if (!file)
+		return NULL;
+
+	if (file->f_op != &sync_file_fops)
+		goto err;
+
+	return file->private_data;
+
+err:
+	fput(file);
+	return NULL;
+}
+EXPORT_SYMBOL(sync_file_fdget);
+
+void sync_file_put(struct sync_file *sync_file)
+{
+	fput(sync_file->file);
+}
+EXPORT_SYMBOL(sync_file_put);
+
+void sync_file_install(struct sync_file *sync_file, int fd)
+{
+	fd_install(fd, sync_file->file);
+}
+EXPORT_SYMBOL(sync_file_install);
+
+static void sync_file_add_pt(struct sync_file *sync_file, int *i,
+			     struct fence *fence)
+{
+	sync_file->cbs[*i].fence = fence;
+	sync_file->cbs[*i].sync_file = sync_file;
+
+	if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
+				fence_check_cb_func)) {
+		fence_get(fence);
+		(*i)++;
+	}
+}
+
+struct sync_file *sync_file_merge(const char *name,
+				  struct sync_file *a, struct sync_file *b)
+{
+	int num_fences = a->num_fences + b->num_fences;
+	struct sync_file *sync_file;
+	int i, i_a, i_b;
+	unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
+
+	sync_file = sync_file_alloc(size, name);
+	if (!sync_file)
+		return NULL;
+
+	atomic_set(&sync_file->status, num_fences);
+
+	/*
+	 * Assume sync_file a and b are both ordered and have no
+	 * duplicates with the same context.
+	 *
+	 * If a sync_file can only be created with sync_file_merge
+	 * and sync_file_create, this is a reasonable assumption.
+	 */
+	for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
+		struct fence *pt_a = a->cbs[i_a].fence;
+		struct fence *pt_b = b->cbs[i_b].fence;
+
+		if (pt_a->context < pt_b->context) {
+			sync_file_add_pt(sync_file, &i, pt_a);
+
+			i_a++;
+		} else if (pt_a->context > pt_b->context) {
+			sync_file_add_pt(sync_file, &i, pt_b);
+
+			i_b++;
+		} else {
+			if (pt_a->seqno - pt_b->seqno <= INT_MAX)
+				sync_file_add_pt(sync_file, &i, pt_a);
+			else
+				sync_file_add_pt(sync_file, &i, pt_b);
+
+			i_a++;
+			i_b++;
+		}
+	}
+
+	for (; i_a < a->num_fences; i_a++)
+		sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
+
+	for (; i_b < b->num_fences; i_b++)
+		sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
+
+	if (num_fences > i)
+		atomic_sub(num_fences - i, &sync_file->status);
+	sync_file->num_fences = i;
+
+	return sync_file;
+}
+EXPORT_SYMBOL(sync_file_merge);
+
+static void sync_file_free(struct kref *kref)
+{
+	struct sync_file *sync_file = container_of(kref, struct sync_file,
+						     kref);
+	int i;
+
+	for (i = 0; i < sync_file->num_fences; ++i) {
+		fence_remove_callback(sync_file->cbs[i].fence,
+				      &sync_file->cbs[i].cb);
+		fence_put(sync_file->cbs[i].fence);
+	}
+
+	kfree(sync_file);
+}
+
+static int sync_file_release(struct inode *inode, struct file *file)
+{
+	struct sync_file *sync_file = file->private_data;
+
+	kref_put(&sync_file->kref, sync_file_free);
+	return 0;
+}
+
+static unsigned int sync_file_poll(struct file *file, poll_table *wait)
+{
+	struct sync_file *sync_file = file->private_data;
+	int status;
+
+	poll_wait(file, &sync_file->wq, wait);
+
+	status = atomic_read(&sync_file->status);
+
+	if (!status)
+		return POLLIN;
+	if (status < 0)
+		return POLLERR;
+	return 0;
+}
+
+static long sync_file_ioctl_merge(struct sync_file *sync_file,
+				   unsigned long arg)
+{
+	int fd = get_unused_fd_flags(O_CLOEXEC);
+	int err;
+	struct sync_file *fence2, *fence3;
+	struct sync_merge_data data;
+
+	if (fd < 0)
+		return fd;
+
+	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
+		err = -EFAULT;
+		goto err_put_fd;
+	}
+
+	if (data.flags || data.pad) {
+		err = -EINVAL;
+		goto err_put_fd;
+	}
+
+	fence2 = sync_file_fdget(data.fd2);
+	if (!fence2) {
+		err = -ENOENT;
+		goto err_put_fd;
+	}
+
+	data.name[sizeof(data.name) - 1] = '\0';
+	fence3 = sync_file_merge(data.name, sync_file, fence2);
+	if (!fence3) {
+		err = -ENOMEM;
+		goto err_put_fence2;
+	}
+
+	data.fence = fd;
+	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
+		err = -EFAULT;
+		goto err_put_fence3;
+	}
+
+	sync_file_install(fence3, fd);
+	sync_file_put(fence2);
+	return 0;
+
+err_put_fence3:
+	sync_file_put(fence3);
+
+err_put_fence2:
+	sync_file_put(fence2);
+
+err_put_fd:
+	put_unused_fd(fd);
+	return err;
+}
+
+static void sync_fill_fence_info(struct fence *fence,
+				struct sync_fence_info *info)
+{
+	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
+		sizeof(info->obj_name));
+	strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
+		sizeof(info->driver_name));
+	if (fence_is_signaled(fence))
+		info->status = fence->status >= 0 ? 1 : fence->status;
+	else
+		info->status = 0;
+	info->timestamp_ns = ktime_to_ns(fence->timestamp);
+}
+
+static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
+					unsigned long arg)
+{
+	struct sync_file_info info;
+	struct sync_fence_info *fence_info = NULL;
+	__u32 size;
+	int ret, i;
+
+	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
+		return -EFAULT;
+
+	if (info.flags || info.pad)
+		return -EINVAL;
+
+	/*
+	 * Passing num_fences = 0 means that userspace doesn't want to
+	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
+	 * sync_fence_info and return the actual number of fences on
+	 * info->num_fences.
+	 */
+	if (!info.num_fences)
+		goto no_fences;
+
+	if (info.num_fences < sync_file->num_fences)
+		return -EINVAL;
+
+	size = sync_file->num_fences * sizeof(*fence_info);
+	fence_info = kzalloc(size, GFP_KERNEL);
+	if (!fence_info)
+		return -ENOMEM;
+
+	for (i = 0; i < sync_file->num_fences; ++i)
+		sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
+
+	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
+			 size)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+no_fences:
+	strlcpy(info.name, sync_file->name, sizeof(info.name));
+	info.status = atomic_read(&sync_file->status);
+	if (info.status >= 0)
+		info.status = !info.status;
+
+	info.num_fences = sync_file->num_fences;
+
+	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
+		ret = -EFAULT;
+	else
+		ret = 0;
+
+out:
+	kfree(fence_info);
+
+	return ret;
+}
+
+static long sync_file_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct sync_file *sync_file = file->private_data;
+
+	switch (cmd) {
+	case SYNC_IOC_MERGE:
+		return sync_file_ioctl_merge(sync_file, arg);
+
+	case SYNC_IOC_FILE_INFO:
+		return sync_file_ioctl_fence_info(sync_file, arg);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations sync_file_fops = {
+	.release = sync_file_release,
+	.poll = sync_file_poll,
+	.unlocked_ioctl = sync_file_ioctl,
+	.compat_ioctl = sync_file_ioctl,
+};
+
diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index bd90d20..2756988 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -52,6 +52,7 @@  config SW_SYNC
 	bool "Software synchronization objects"
 	default n
 	depends on SYNC
+	depends on SYNC_FILE
 	---help---
 	  A sync object driver that uses a 32bit counter to coordinate
 	  synchronization.  Useful when there is no hardware primitive backing
diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index f9c6094..1d14c83 100644
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -16,10 +16,7 @@ 
 
 #include <linux/debugfs.h>
 #include <linux/export.h>
-#include <linux/file.h>
-#include <linux/fs.h>
 #include <linux/kernel.h>
-#include <linux/poll.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
@@ -32,7 +29,6 @@ 
 #include "trace/sync.h"
 
 static const struct fence_ops android_fence_ops;
-static const struct file_operations sync_file_fops;
 
 struct sync_timeline *sync_timeline_create(const struct sync_timeline_ops *ops,
 					   int size, const char *name)
@@ -136,170 +132,6 @@  struct fence *sync_pt_create(struct sync_timeline *obj, int size)
 }
 EXPORT_SYMBOL(sync_pt_create);
 
-static struct sync_file *sync_file_alloc(int size, const char *name)
-{
-	struct sync_file *sync_file;
-
-	sync_file = kzalloc(size, GFP_KERNEL);
-	if (!sync_file)
-		return NULL;
-
-	sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
-					     sync_file, 0);
-	if (IS_ERR(sync_file->file))
-		goto err;
-
-	kref_init(&sync_file->kref);
-	strlcpy(sync_file->name, name, sizeof(sync_file->name));
-
-	init_waitqueue_head(&sync_file->wq);
-
-	return sync_file;
-
-err:
-	kfree(sync_file);
-	return NULL;
-}
-
-static void fence_check_cb_func(struct fence *f, struct fence_cb *cb)
-{
-	struct sync_file_cb *check;
-	struct sync_file *sync_file;
-
-	check = container_of(cb, struct sync_file_cb, cb);
-	sync_file = check->sync_file;
-
-	if (atomic_dec_and_test(&sync_file->status))
-		wake_up_all(&sync_file->wq);
-}
-
-/* TODO: implement a create which takes more that one fence */
-struct sync_file *sync_file_create(const char *name, struct fence *fence)
-{
-	struct sync_file *sync_file;
-
-	sync_file = sync_file_alloc(offsetof(struct sync_file, cbs[1]),
-				    name);
-	if (!sync_file)
-		return NULL;
-
-	sync_file->num_fences = 1;
-	atomic_set(&sync_file->status, 1);
-
-	sync_file->cbs[0].fence = fence;
-	sync_file->cbs[0].sync_file = sync_file;
-	if (fence_add_callback(fence, &sync_file->cbs[0].cb,
-			       fence_check_cb_func))
-		atomic_dec(&sync_file->status);
-
-	sync_file_debug_add(sync_file);
-
-	return sync_file;
-}
-EXPORT_SYMBOL(sync_file_create);
-
-struct sync_file *sync_file_fdget(int fd)
-{
-	struct file *file = fget(fd);
-
-	if (!file)
-		return NULL;
-
-	if (file->f_op != &sync_file_fops)
-		goto err;
-
-	return file->private_data;
-
-err:
-	fput(file);
-	return NULL;
-}
-EXPORT_SYMBOL(sync_file_fdget);
-
-void sync_file_put(struct sync_file *sync_file)
-{
-	fput(sync_file->file);
-}
-EXPORT_SYMBOL(sync_file_put);
-
-void sync_file_install(struct sync_file *sync_file, int fd)
-{
-	fd_install(fd, sync_file->file);
-}
-EXPORT_SYMBOL(sync_file_install);
-
-static void sync_file_add_pt(struct sync_file *sync_file, int *i,
-			     struct fence *fence)
-{
-	sync_file->cbs[*i].fence = fence;
-	sync_file->cbs[*i].sync_file = sync_file;
-
-	if (!fence_add_callback(fence, &sync_file->cbs[*i].cb,
-				fence_check_cb_func)) {
-		fence_get(fence);
-		(*i)++;
-	}
-}
-
-struct sync_file *sync_file_merge(const char *name,
-				  struct sync_file *a, struct sync_file *b)
-{
-	int num_fences = a->num_fences + b->num_fences;
-	struct sync_file *sync_file;
-	int i, i_a, i_b;
-	unsigned long size = offsetof(struct sync_file, cbs[num_fences]);
-
-	sync_file = sync_file_alloc(size, name);
-	if (!sync_file)
-		return NULL;
-
-	atomic_set(&sync_file->status, num_fences);
-
-	/*
-	 * Assume sync_file a and b are both ordered and have no
-	 * duplicates with the same context.
-	 *
-	 * If a sync_file can only be created with sync_file_merge
-	 * and sync_file_create, this is a reasonable assumption.
-	 */
-	for (i = i_a = i_b = 0; i_a < a->num_fences && i_b < b->num_fences; ) {
-		struct fence *pt_a = a->cbs[i_a].fence;
-		struct fence *pt_b = b->cbs[i_b].fence;
-
-		if (pt_a->context < pt_b->context) {
-			sync_file_add_pt(sync_file, &i, pt_a);
-
-			i_a++;
-		} else if (pt_a->context > pt_b->context) {
-			sync_file_add_pt(sync_file, &i, pt_b);
-
-			i_b++;
-		} else {
-			if (pt_a->seqno - pt_b->seqno <= INT_MAX)
-				sync_file_add_pt(sync_file, &i, pt_a);
-			else
-				sync_file_add_pt(sync_file, &i, pt_b);
-
-			i_a++;
-			i_b++;
-		}
-	}
-
-	for (; i_a < a->num_fences; i_a++)
-		sync_file_add_pt(sync_file, &i, a->cbs[i_a].fence);
-
-	for (; i_b < b->num_fences; i_b++)
-		sync_file_add_pt(sync_file, &i, b->cbs[i_b].fence);
-
-	if (num_fences > i)
-		atomic_sub(num_fences - i, &sync_file->status);
-	sync_file->num_fences = i;
-
-	sync_file_debug_add(sync_file);
-	return sync_file;
-}
-EXPORT_SYMBOL(sync_file_merge);
-
 static const char *android_fence_get_driver_name(struct fence *fence)
 {
 	struct sync_timeline *parent = fence_parent(fence);
@@ -387,197 +219,3 @@  static const struct fence_ops android_fence_ops = {
 	.fence_value_str = android_fence_value_str,
 	.timeline_value_str = android_fence_timeline_value_str,
 };
-
-static void sync_file_free(struct kref *kref)
-{
-	struct sync_file *sync_file = container_of(kref, struct sync_file,
-						     kref);
-	int i;
-
-	for (i = 0; i < sync_file->num_fences; ++i) {
-		fence_remove_callback(sync_file->cbs[i].fence,
-				      &sync_file->cbs[i].cb);
-		fence_put(sync_file->cbs[i].fence);
-	}
-
-	kfree(sync_file);
-}
-
-static int sync_file_release(struct inode *inode, struct file *file)
-{
-	struct sync_file *sync_file = file->private_data;
-
-	sync_file_debug_remove(sync_file);
-
-	kref_put(&sync_file->kref, sync_file_free);
-	return 0;
-}
-
-static unsigned int sync_file_poll(struct file *file, poll_table *wait)
-{
-	struct sync_file *sync_file = file->private_data;
-	int status;
-
-	poll_wait(file, &sync_file->wq, wait);
-
-	status = atomic_read(&sync_file->status);
-
-	if (!status)
-		return POLLIN;
-	if (status < 0)
-		return POLLERR;
-	return 0;
-}
-
-static long sync_file_ioctl_merge(struct sync_file *sync_file,
-				   unsigned long arg)
-{
-	int fd = get_unused_fd_flags(O_CLOEXEC);
-	int err;
-	struct sync_file *fence2, *fence3;
-	struct sync_merge_data data;
-
-	if (fd < 0)
-		return fd;
-
-	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
-		err = -EFAULT;
-		goto err_put_fd;
-	}
-
-	if (data.flags || data.pad) {
-		err = -EINVAL;
-		goto err_put_fd;
-	}
-
-	fence2 = sync_file_fdget(data.fd2);
-	if (!fence2) {
-		err = -ENOENT;
-		goto err_put_fd;
-	}
-
-	data.name[sizeof(data.name) - 1] = '\0';
-	fence3 = sync_file_merge(data.name, sync_file, fence2);
-	if (!fence3) {
-		err = -ENOMEM;
-		goto err_put_fence2;
-	}
-
-	data.fence = fd;
-	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
-		err = -EFAULT;
-		goto err_put_fence3;
-	}
-
-	sync_file_install(fence3, fd);
-	sync_file_put(fence2);
-	return 0;
-
-err_put_fence3:
-	sync_file_put(fence3);
-
-err_put_fence2:
-	sync_file_put(fence2);
-
-err_put_fd:
-	put_unused_fd(fd);
-	return err;
-}
-
-static void sync_fill_fence_info(struct fence *fence,
-				struct sync_fence_info *info)
-{
-	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
-		sizeof(info->obj_name));
-	strlcpy(info->driver_name, fence->ops->get_driver_name(fence),
-		sizeof(info->driver_name));
-	if (fence_is_signaled(fence))
-		info->status = fence->status >= 0 ? 1 : fence->status;
-	else
-		info->status = 0;
-	info->timestamp_ns = ktime_to_ns(fence->timestamp);
-}
-
-static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
-					unsigned long arg)
-{
-	struct sync_file_info info;
-	struct sync_fence_info *fence_info = NULL;
-	__u32 size;
-	int ret, i;
-
-	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
-		return -EFAULT;
-
-	if (info.flags || info.pad)
-		return -EINVAL;
-
-	/*
-	 * Passing num_fences = 0 means that userspace doesn't want to
-	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
-	 * sync_fence_info and return the actual number of fences on
-	 * info->num_fences.
-	 */
-	if (!info.num_fences)
-		goto no_fences;
-
-	if (info.num_fences < sync_file->num_fences)
-		return -EINVAL;
-
-	size = sync_file->num_fences * sizeof(*fence_info);
-	fence_info = kzalloc(size, GFP_KERNEL);
-	if (!fence_info)
-		return -ENOMEM;
-
-	for (i = 0; i < sync_file->num_fences; ++i)
-		sync_fill_fence_info(sync_file->cbs[i].fence, &fence_info[i]);
-
-	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
-			 size)) {
-		ret = -EFAULT;
-		goto out;
-	}
-
-no_fences:
-	strlcpy(info.name, sync_file->name, sizeof(info.name));
-	info.status = atomic_read(&sync_file->status);
-	if (info.status >= 0)
-		info.status = !info.status;
-
-	info.num_fences = sync_file->num_fences;
-
-	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
-		ret = -EFAULT;
-	else
-		ret = 0;
-
-out:
-	kfree(fence_info);
-
-	return ret;
-}
-
-static long sync_file_ioctl(struct file *file, unsigned int cmd,
-			     unsigned long arg)
-{
-	struct sync_file *sync_file = file->private_data;
-
-	switch (cmd) {
-	case SYNC_IOC_MERGE:
-		return sync_file_ioctl_merge(sync_file, arg);
-
-	case SYNC_IOC_FILE_INFO:
-		return sync_file_ioctl_fence_info(sync_file, arg);
-
-	default:
-		return -ENOTTY;
-	}
-}
-
-static const struct file_operations sync_file_fops = {
-	.release = sync_file_release,
-	.poll = sync_file_poll,
-	.unlocked_ioctl = sync_file_ioctl,
-	.compat_ioctl = sync_file_ioctl,
-};
-
diff --git a/drivers/staging/android/sync.h b/drivers/staging/android/sync.h
index d2a1734..97574be 100644
--- a/drivers/staging/android/sync.h
+++ b/drivers/staging/android/sync.h
@@ -19,11 +19,10 @@ 
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/fence.h>
-
-#include "uapi/sync.h"
+#include <linux/sync_file.h>
+#include <uapi/linux/sync_file.h>
 
 struct sync_timeline;
-struct sync_file;
 
 /**
  * struct sync_timeline_ops - sync object implementation ops
@@ -86,38 +85,6 @@  static inline struct sync_timeline *fence_parent(struct fence *fence)
 			    child_list_lock);
 }
 
-struct sync_file_cb {
-	struct fence_cb cb;
-	struct fence *fence;
-	struct sync_file *sync_file;
-};
-
-/**
- * struct sync_file - sync file to export to the userspace
- * @file:		file representing this fence
- * @kref:		reference count on fence.
- * @name:		name of sync_file.  Useful for debugging
- * @sync_file_list:	membership in global file list
- * @num_fences		number of sync_pts in the fence
- * @wq:			wait queue for fence signaling
- * @status:		0: signaled, >0:active, <0: error
- * @cbs:		sync_pts callback information
- */
-struct sync_file {
-	struct file		*file;
-	struct kref		kref;
-	char			name[32];
-#ifdef CONFIG_DEBUG_FS
-	struct list_head	sync_file_list;
-#endif
-	int num_fences;
-
-	wait_queue_head_t	wq;
-	atomic_t		status;
-
-	struct sync_file_cb	cbs[];
-};
-
 /*
  * API for sync_timeline implementers
  */
@@ -167,61 +134,6 @@  void sync_timeline_signal(struct sync_timeline *obj);
  */
 struct fence *sync_pt_create(struct sync_timeline *parent, int size);
 
-/**
- * sync_fence_create() - creates a sync fence
- * @name:	name of fence to create
- * @fence:	fence to add to the sync_fence
- *
- * Creates a sync_file containg @fence. Once this is called, the sync_file
- * takes ownership of @fence.
- */
-struct sync_file *sync_file_create(const char *name, struct fence *fence);
-
-/*
- * API for sync_file consumers
- */
-
-/**
- * sync_file_merge() - merge two sync_files
- * @name:	name of new fence
- * @a:		sync_file a
- * @b:		sync_file b
- *
- * Creates a new sync_file which contains copies of all the fences in both
- * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
- * new merged sync_file or NULL in case of error.
- */
-struct sync_file *sync_file_merge(const char *name,
-				    struct sync_file *a, struct sync_file *b);
-
-/**
- * sync_file_fdget() - get a sync_file from an fd
- * @fd:		fd referencing a fence
- *
- * Ensures @fd references a valid sync_file, increments the refcount of the
- * backing file. Returns the sync_file or NULL in case of error.
- */
-struct sync_file *sync_file_fdget(int fd);
-
-/**
- * sync_file_put() - puts a reference of a sync_file
- * @sync_file:	sync_file to put
- *
- * Puts a reference on @sync_fence.  If this is the last reference, the
- * sync_fil and all it's sync_pts will be freed
- */
-void sync_file_put(struct sync_file *sync_file);
-
-/**
- * sync_file_install() - installs a sync_file into a file descriptor
- * @sync_file:	sync_file to install
- * @fd:		file descriptor in which to install the fence
- *
- * Installs @sync_file into @fd.  @fd's should be acquired through
- * get_unused_fd_flags(O_CLOEXEC).
- */
-void sync_file_install(struct sync_file *sync_file, int fd);
-
 #ifdef CONFIG_DEBUG_FS
 
 void sync_timeline_debug_add(struct sync_timeline *obj);
diff --git a/drivers/staging/android/sync_debug.c b/drivers/staging/android/sync_debug.c
index 5a7ec58..e5b14f0 100644
--- a/drivers/staging/android/sync_debug.c
+++ b/drivers/staging/android/sync_debug.c
@@ -26,6 +26,7 @@ 
 #include <linux/uaccess.h>
 #include <linux/anon_inodes.h>
 #include <linux/time64.h>
+#include <linux/sync_file.h>
 #include "sw_sync.h"
 
 #ifdef CONFIG_DEBUG_FS
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
new file mode 100644
index 0000000..7b7a89d
--- /dev/null
+++ b/include/linux/sync_file.h
@@ -0,0 +1,106 @@ 
+/*
+ * include/linux/sync_file.h
+ *
+ * Copyright (C) 2012 Google, Inc.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _LINUX_SYNC_FILE_H
+#define _LINUX_SYNC_FILE_H
+
+#include <linux/types.h>
+#include <linux/kref.h>
+#include <linux/ktime.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/fence.h>
+
+struct sync_file_cb {
+	struct fence_cb cb;
+	struct fence *fence;
+	struct sync_file *sync_file;
+};
+
+/**
+ * struct sync_file - sync file to export to the userspace
+ * @file:		file representing this fence
+ * @kref:		reference count on fence.
+ * @name:		name of sync_file.  Useful for debugging
+ * @sync_file_list:	membership in global file list
+ * @num_fences		number of sync_pts in the fence
+ * @wq:			wait queue for fence signaling
+ * @status:		0: signaled, >0:active, <0: error
+ * @cbs:		sync_pts callback information
+ */
+struct sync_file {
+	struct file		*file;
+	struct kref		kref;
+	char			name[32];
+#ifdef CONFIG_DEBUG_FS
+	struct list_head	sync_file_list;
+#endif
+	int num_fences;
+
+	wait_queue_head_t	wq;
+	atomic_t		status;
+
+	struct sync_file_cb	cbs[];
+};
+
+/**
+ * sync_file_create() - creates a sync file
+ * @name:	name of fence to create
+ * @fence:	fence to add to the sync_file
+ *
+ * Creates a sync_file containg @fence. Once this is called, the sync_file
+ * takes ownership of @fence.
+ */
+struct sync_file *sync_file_create(const char *name, struct fence *fence);
+
+/**
+ * sync_file_merge() - merge two sync_files
+ * @name:	name of new fence
+ * @a:		sync_file a
+ * @b:		sync_file b
+ *
+ * Creates a new sync_file which contains copies of all the fences in both
+ * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
+ * new merged sync_file or NULL in case of error.
+ */
+struct sync_file *sync_file_merge(const char *name,
+				    struct sync_file *a, struct sync_file *b);
+
+/**
+ * sync_file_fdget() - get a sync_file from an fd
+ * @fd:		fd referencing a fence
+ *
+ * Ensures @fd references a valid sync_file, increments the refcount of the
+ * backing file. Returns the sync_file or NULL in case of error.
+ */
+struct sync_file *sync_file_fdget(int fd);
+
+/**
+ * sync_file_put() - puts a reference of a sync_file
+ * @sync_file:	sync_file to put
+ *
+ * Puts a reference on @sync_fence.  If this is the last reference, the
+ * sync_fil and all it's sync_pts will be freed
+ */
+void sync_file_put(struct sync_file *sync_file);
+
+/**
+ * sync_file_install() - installs a sync_file into a file descriptor
+ * @sync_file:	sync_file to install
+ * @fd:		file descriptor in which to install the fence
+ *
+ * Installs @sync_file into @fd.  @fd's should be acquired through
+ * get_unused_fd_flags(O_CLOEXEC).
+ */
+void sync_file_install(struct sync_file *sync_file, int fd);
+
+#endif /* _LINUX_SYNC_H */