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SubjectRe: [RFC v1 00/14] Bus1 Kernel Message Bus
[CC += linuux-api]@vger.kernel.org

Hi David,

Could you please CC linux-api@ on all future iterations of this patch!

Cheers,

Michael



On Wed, Oct 26, 2016 at 9:17 PM, David Herrmann <dh.herrmann@gmail.com> wrote:
> Hi
>
> This proposal introduces bus1.ko, a kernel messaging bus. This is not a request
> for inclusion, yet. It is rather an initial draft and a Request For Comments.
>
> While bus1 emerged out of the kdbus project, bus1 was started from scratch and
> the concepts have little in common. In a nutshell, bus1 provides a
> capability-based IPC system, similar in nature to Android Binder, Cap'n Proto,
> and seL4. The module is completely generic and does neither require nor mandate
> a user-space counter-part.
>
> o Description
>
> Bus1 is a local IPC system, which provides a decentralized infrastructure to
> share objects between local peers. The main building blocks are nodes and
> handles. Nodes represent objects of a local peer, while handles represent
> descriptors that point to a node. Nodes can be created and destroyed by any
> peer, and they will always remain owned by their respective creator. Handles
> on the other hand, are used to refer to nodes and can be passed around with
> messages as auxiliary data. Whenever a handle is transferred, the receiver
> will get its own handle allocated, pointing to the same node as the original
> handle.
>
> Any peer can send messages directed at one of their handles. This will
> transfer the message to the owner of the node the handle points to. If a
> peer does not posess a handle to a given node, it will not be able to send a
> message to that node. That is, handles provide exclusive access management.
> Anyone that somehow acquired a handle to a node is privileged to further
> send this handle to other peers. As such, access management is transitive.
> Once a peer acquired a handle, it cannot be revoked again. However, a node
> owner can, at anytime, destroy a node. This will effectively unbind all
> existing handles to that node on any peer, notifying each one of the
> destruction.
>
> Unlike nodes and handles, peers cannot be addressed directly. In fact, peers
> are completely disconnected entities. A peer is merely an anchor of a set of
> nodes and handles, including an incoming message queue for any of those.
> Whether multiple nodes are all part of the same peer, or part of different
> peers does not affect the remote view of those. Peers solely exist as
> management entity and command dispatcher to local processes.
>
> The set of actors on a system is completely decentralized. There is no
> global component involved that provides a central registry or discovery
> mechanism. Furthermore, communication between peers only involves those
> peers, and does not affect any other peer in any way. No global
> communication lock is taken. However, any communication is still globally
> ordered, including unicasts, multicasts, and notifications.
>
> o Prior Art
>
> The concepts behind bus1 are almost identical to capability systems like
> Android Binder, Google Mojo, Cap'n Proto, seL4, and more. Bus1 differs from
> them by supporting Global Ordering, Multicasts, Resource Accounting, No
> Global Locking, No Global Context.
>
> While the bus1 UAPI does not expose all features (like soft-references as
> supported by Binder), the in-kernel code includes support for it. Multiple
> UAPIs can be supported on top of the in-kernel bus1 code, including support
> for the Binder UAPI. Efforts on this are still on-going.
>
> o Documentation
>
> The first patch in this series provides the bus1(7) man-page. It explains
> all concepts in bus1 in more detail. Furthermore, it describes the API that
> is available on bus1 file descriptors. The pre-compiled man-page is
> available at:
>
> http://www.bus1.org/bus1.html
>
> There is also a great bunch of in-source documentation available. All
> cross-source-file APIs have KernelDoc annotations. Furthermore, we have an
> introduction for each subsystem, to be found in the header files. The total
> number in lines of code for bus1 is roughly ~4.5k. The remaining ~5k LOC
> are comments and documentation.
>
> o Upstream
>
> The upstream development repository is available on github:
>
> http://github.com/bus1/bus1
>
> It is an out-of-tree repository that allows easy and fast development of
> new bus1 features. The in-tree integration repository is available at:
>
> http://github.com/bus1/linux
>
> o Conferences
>
> Tom and I will be attending Linux Plumbers Conf next week. Please do not
> hesitate to contact us there in person. There will also be a presentation
> [1] of bus1 on the last day of the conference.
>
> Thanks
> Tom & David
>
> [1] https://www.linuxplumbersconf.org/2016/ocw/proposals/3819
>
> Tom Gundersen (14):
> bus1: add bus1(7) man-page
> bus1: provide stub cdev /dev/bus1
> bus1: util - active reference utility library
> bus1: util - fixed list utility library
> bus1: util - pool utility library
> bus1: util - queue utility library
> bus1: tracking user contexts
> bus1: implement peer management context
> bus1: provide transaction context for multicasts
> bus1: add handle management
> bus1: implement message transmission
> bus1: hook up file-operations
> bus1: limit and protect resources
> bus1: basic user-space kselftests
>
> Documentation/bus1/.gitignore | 2 +
> Documentation/bus1/Makefile | 41 +
> Documentation/bus1/bus1.xml | 833 +++++++++++++++++++++
> Documentation/bus1/stylesheet.xsl | 16 +
> include/uapi/linux/bus1.h | 138 ++++
> init/Kconfig | 17 +
> ipc/Makefile | 1 +
> ipc/bus1/Makefile | 16 +
> ipc/bus1/handle.c | 823 ++++++++++++++++++++
> ipc/bus1/handle.h | 312 ++++++++
> ipc/bus1/main.c | 146 ++++
> ipc/bus1/main.h | 88 +++
> ipc/bus1/message.c | 656 ++++++++++++++++
> ipc/bus1/message.h | 171 +++++
> ipc/bus1/peer.c | 1163 +++++++++++++++++++++++++++++
> ipc/bus1/peer.h | 163 ++++
> ipc/bus1/security.h | 45 ++
> ipc/bus1/tests.c | 19 +
> ipc/bus1/tests.h | 32 +
> ipc/bus1/tx.c | 360 +++++++++
> ipc/bus1/tx.h | 102 +++
> ipc/bus1/user.c | 628 ++++++++++++++++
> ipc/bus1/user.h | 140 ++++
> ipc/bus1/util.c | 214 ++++++
> ipc/bus1/util.h | 141 ++++
> ipc/bus1/util/active.c | 419 +++++++++++
> ipc/bus1/util/active.h | 154 ++++
> ipc/bus1/util/flist.c | 116 +++
> ipc/bus1/util/flist.h | 202 +++++
> ipc/bus1/util/pool.c | 572 ++++++++++++++
> ipc/bus1/util/pool.h | 164 ++++
> ipc/bus1/util/queue.c | 445 +++++++++++
> ipc/bus1/util/queue.h | 351 +++++++++
> tools/testing/selftests/bus1/.gitignore | 2 +
> tools/testing/selftests/bus1/Makefile | 19 +
> tools/testing/selftests/bus1/bus1-ioctl.h | 111 +++
> tools/testing/selftests/bus1/test-api.c | 532 +++++++++++++
> tools/testing/selftests/bus1/test-io.c | 198 +++++
> tools/testing/selftests/bus1/test.h | 114 +++
> 39 files changed, 9666 insertions(+)
> create mode 100644 Documentation/bus1/.gitignore
> create mode 100644 Documentation/bus1/Makefile
> create mode 100644 Documentation/bus1/bus1.xml
> create mode 100644 Documentation/bus1/stylesheet.xsl
> create mode 100644 include/uapi/linux/bus1.h
> create mode 100644 ipc/bus1/Makefile
> create mode 100644 ipc/bus1/handle.c
> create mode 100644 ipc/bus1/handle.h
> create mode 100644 ipc/bus1/main.c
> create mode 100644 ipc/bus1/main.h
> create mode 100644 ipc/bus1/message.c
> create mode 100644 ipc/bus1/message.h
> create mode 100644 ipc/bus1/peer.c
> create mode 100644 ipc/bus1/peer.h
> create mode 100644 ipc/bus1/security.h
> create mode 100644 ipc/bus1/tests.c
> create mode 100644 ipc/bus1/tests.h
> create mode 100644 ipc/bus1/tx.c
> create mode 100644 ipc/bus1/tx.h
> create mode 100644 ipc/bus1/user.c
> create mode 100644 ipc/bus1/user.h
> create mode 100644 ipc/bus1/util.c
> create mode 100644 ipc/bus1/util.h
> create mode 100644 ipc/bus1/util/active.c
> create mode 100644 ipc/bus1/util/active.h
> create mode 100644 ipc/bus1/util/flist.c
> create mode 100644 ipc/bus1/util/flist.h
> create mode 100644 ipc/bus1/util/pool.c
> create mode 100644 ipc/bus1/util/pool.h
> create mode 100644 ipc/bus1/util/queue.c
> create mode 100644 ipc/bus1/util/queue.h
> create mode 100644 tools/testing/selftests/bus1/.gitignore
> create mode 100644 tools/testing/selftests/bus1/Makefile
> create mode 100644 tools/testing/selftests/bus1/bus1-ioctl.h
> create mode 100644 tools/testing/selftests/bus1/test-api.c
> create mode 100644 tools/testing/selftests/bus1/test-io.c
> create mode 100644 tools/testing/selftests/bus1/test.h
>
> --
> 2.10.1
>



--
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/

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