selftests: drivers/dma-buf: Improve message in selftest summary

Selftest udmabuf for the dma-buf driver is skipped when the device file
(e.g. /dev/udmabuf) for the DMA buffer cannot be opened i.e. no DMA buffer
has been allocated.

This patch adds clarity to the SKIP message.

Signed-off-by: Soumya Negi <soumya.negi97@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests: drivers/dma-buf: Fix implicit declaration warns

udmabuf has the following implicit declaration warns:

udmabuf.c:30:10: warning: implicit declaration of function 'open';
udmabuf.c:42:8: warning: implicit declaration of function 'fcntl'

These are caused due to not including fcntl.h and including just
linux/fcntl.h. Fix it to include fcntl.h which will bring in the
linux/fcntl.h. In addition, define __EXPORTED_HEADERS__ to bring in
F_ADD_SEALS and F_SEAL_SHRINK defines and fix the following error
that show up when just fcntl.h is included.

udmabuf.c:45:21: error: 'F_ADD_SEALS' undeclared
45 | ret = fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK);
| ^~~~~~~~~~~
udmabuf.c:45:34: error: 'F_SEAL_SHRINK' undeclared
45 | ret = fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK);
| ^~~~~~~~~~~~~

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

fix dma-buf/udmabuf selftest

This patch fixes the udmabuf selftest. Currently the selftest is broken.
I fixed the selftest by setting the F_SEAL_SHRINK seal on the memfd
file descriptor which is required by udmabuf and added the test to
the selftest Makefile.

Signed-off-by: Tom Murphy <murphyt7@tcd.ie>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Shuah Khan <shuah@kernel.org>

Add udmabuf misc device

A driver to let userspace turn memfd regions into dma-bufs.

Use case: Allows qemu create dmabufs for the vga framebuffer or
virtio-gpu ressources. Then they can be passed around to display
those guest things on the host. To spice client for classic full
framebuffer display, and hopefully some day to wayland server for
seamless guest window display.

qemu test branch:
https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf

Cc: David Airlie <airlied@linux.ie>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20180827093444.23623-1-kraxel@redhat.com