dma-buf: Final bits of doc polish

- Put all the remaing bits of the old doc into suitable places in the
  new sphinx world.
- Also document the poll support, we forgot to do that.
- Delete dma-buf-sharing.txt.

v2: Don't forget to update MAINTAINERS.

Cc: linux-doc@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20161209215055.3492-1-daniel.vetter@ffwll.ch

1 files changed, 0 insertions, 47 deletions

diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt
deleted file mode 100644
index 74c99ed..0000000
--- a/Documentation/dma-buf-sharing.txt
+++ /dev/null
@@ -1,47 +0,0 @@
-                    DMA Buffer Sharing API Guide
-                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-                            Sumit Semwal
-                <sumit dot semwal at linaro dot org>
-                 <sumit dot semwal at ti dot com>
-
-
-Other Interfaces Exposed to Userspace on the dma-buf FD
-------------------------------------------------------
-
-- Since kernel 3.12 the dma-buf FD supports the llseek system call, but only
-  with offset=0 and whence=SEEK_END|SEEK_SET. SEEK_SET is supported to allow
-  the usual size discover pattern size = SEEK_END(0); SEEK_SET(0). Every other
-  llseek operation will report -EINVAL.
-
-  If llseek on dma-buf FDs isn't support the kernel will report -ESPIPE for all
-  cases. Userspace can use this to detect support for discovering the dma-buf
-  size using llseek.
-
-Miscellaneous notes
--------------------
-
-- Any exporters or users of the dma-buf buffer sharing framework must have
-  a 'select DMA_SHARED_BUFFER' in their respective Kconfigs.
-
-- In order to avoid fd leaks on exec, the FD_CLOEXEC flag must be set
-  on the file descriptor.  This is not just a resource leak, but a
-  potential security hole.  It could give the newly exec'd application
-  access to buffers, via the leaked fd, to which it should otherwise
-  not be permitted access.
-
-  The problem with doing this via a separate fcntl() call, versus doing it
-  atomically when the fd is created, is that this is inherently racy in a
-  multi-threaded app[3].  The issue is made worse when it is library code
-  opening/creating the file descriptor, as the application may not even be
-  aware of the fd's.
-
-  To avoid this problem, userspace must have a way to request O_CLOEXEC
-  flag be set when the dma-buf fd is created.  So any API provided by
-  the exporting driver to create a dmabuf fd must provide a way to let
-  userspace control setting of O_CLOEXEC flag passed in to dma_buf_fd().
-
-References:
-[1] struct dma_buf_ops in include/linux/dma-buf.h
-[2] All interfaces mentioned above defined in include/linux/dma-buf.h
-[3] https://lwn.net/Articles/236486/