[UNIKRAFT PATCH 0/5] Introduce Ring Buffer Implementation

[Alexander Jung <a.jung@xxxxxxxxxxx>]

From: Alexander Jung <alexander.jung@xxxxxxxxx>

This series introduces a port of FreeBSD's buf_ring.{h,c} implementation for use
within Unikraft.  This simple ring buffer can be used for message passing in
queues, for example within a AF_UNIX socket implementation between two 
threads.  The implementation is therefore thread safe and provides a generic 
data field which is initialized to the desired ring buffer length.

The implementation is provided within ukmpi as a new option, LIBUKMPI_RING, 
which exposes the following new methods:

 - uk_ring_alloc
 - uk_ring_free
 - uk_ring_enqueue
 - uk_ring_dequeue
 - uk_ring_dequeue_single
 - uk_ring_advance_single
 - uk_ring_putback_single
 - uk_ring_peek
 - uk_ring_peek_clear_single
 - uk_ring_full
 - uk_ring_empty
 - uk_ring_count

The port is currently limited, with no support for reading atomic values from
ARM{32,64} CPU registers (described in the comments inline).  As a result, use 
of the ring buffer implementation is untested on ARM.

Alexander Jung (5):
  lib/ukmpi: Introduce simple ring interface KConfig option
  lib/ukmpi: Initial port of FreeBSD's buf_ring.h
  lib/ukmpi: Provide ring buffer allocation and free methods
  lib/ukmpi: Include ring buffer into Unikraft build process
  lib/ukmpi: Export the global ring buffer (de)init methods

 lib/ukmpi/Config.uk         |  23 ++-
 lib/ukmpi/Makefile.uk       |   1 +
 lib/ukmpi/exportsyms.uk     |   3 +
 lib/ukmpi/include/uk/ring.h | 474 ++++++++++++++++++++++++++++++++++++++++++++
 lib/ukmpi/ring.c            |  87 ++++++++
 5 files changed, 587 insertions(+), 1 deletion(-)
 create mode 100644 lib/ukmpi/include/uk/ring.h
 create mode 100644 lib/ukmpi/ring.c

-- 
2.11.0