On Tue, Feb 09, 2016 at 12:45:58PM +0100, Paolo Bonzini wrote:
> This is the infrastructure part of the aio_context_acquire/release pushdown,
> which in turn is the first step towards a real multiqueue block layer in
> QEMU.  The next step is to touch all the drivers and move calls to the
> aio_context_acquire/release functions from aio-*.c to the drivers.  This
> will be done in a separate patch series, which I plan to post before soft
> freeze.
> 
> While the inserted lines are a lot, more than half of it are in documentation
> and formal models of the code, as well as in the implementation of the new
> "lockcnt" synchronization primitive.  The code is also very heavily commented.
> 
> The first four patches are new, as the issue they fix was found after posting
> the previous patch.  Everything else is more or less the same as before.
> 
> Paolo
> 
> v1->v2: Update documentation [Stefan]
>         Remove g_usleep from testcase [Stefan]
> 
> v2->v3: Fix broken sentence [Eric]
>         Use osdep.h [Eric]
>         (v2->v3 diff after diffstat)
> 
> Paolo Bonzini (16):
>   aio: introduce aio_context_in_iothread
>   aio: do not really acquire/release the main AIO context
>   aio: introduce aio_poll_internal
>   aio: only call aio_poll_internal from iothread
>   iothread: release AioContext around aio_poll
>   qemu-thread: introduce QemuRecMutex
>   aio: convert from RFifoLock to QemuRecMutex
>   aio: rename bh_lock to list_lock
>   qemu-thread: introduce QemuLockCnt
>   aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh
>   qemu-thread: optimize QemuLockCnt with futexes on Linux
>   aio: tweak walking in dispatch phase
>   aio-posix: remove walking_handlers, protecting AioHandler list with
>     list_lock
>   aio-win32: remove walking_handlers, protecting AioHandler list with
>     list_lock
>   aio: document locking
>   aio: push aio_context_acquire/release down to dispatching
> 
>  aio-posix.c                     |  86 +++++----
>  aio-win32.c                     | 106 ++++++-----
>  async.c                         | 278 ++++++++++++++++++++++++----
>  block/io.c                      |  14 +-
>  docs/aio_poll_drain.promela     | 210 +++++++++++++++++++++
>  docs/aio_poll_drain_bug.promela | 158 ++++++++++++++++
>  docs/aio_poll_sync_io.promela   |  88 +++++++++
>  docs/lockcnt.txt                | 342 ++++++++++++++++++++++++++++++++++
>  docs/multiple-iothreads.txt     |  63 ++++---
>  include/block/aio.h             |  69 ++++---
>  include/qemu/futex.h            |  36 ++++
>  include/qemu/rfifolock.h        |  54 ------
>  include/qemu/thread-posix.h     |   6 +
>  include/qemu/thread-win32.h     |  10 +
>  include/qemu/thread.h           |  23 +++
>  iothread.c                      |  20 +-
>  stubs/iothread-lock.c           |   5 +
>  tests/.gitignore                |   1 -
>  tests/Makefile                  |   2 -
>  tests/test-aio.c                |  22 ++-
>  tests/test-rfifolock.c          |  91 ---------
>  trace-events                    |  10 +
>  util/Makefile.objs              |   2 +-
>  util/lockcnt.c                  | 395 ++++++++++++++++++++++++++++++++++++++++
>  util/qemu-thread-posix.c        |  38 ++--
>  util/qemu-thread-win32.c        |  25 +++
>  util/rfifolock.c                |  78 --------
>  27 files changed, 1782 insertions(+), 450 deletions(-)
>  create mode 100644 docs/aio_poll_drain.promela
>  create mode 100644 docs/aio_poll_drain_bug.promela
>  create mode 100644 docs/aio_poll_sync_io.promela
>  create mode 100644 docs/lockcnt.txt
>  create mode 100644 include/qemu/futex.h
>  delete mode 100644 include/qemu/rfifolock.h
>  delete mode 100644 tests/test-rfifolock.c
>  create mode 100644 util/lockcnt.c
>  delete mode 100644 util/rfifolock.c

I'm getting the following with mingw:

util/qemu-thread-win32.c:87:6: error: conflicting types for 'qemu_rec_mutex_destroy'
 void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
      ^
In file included from /home/stefanha/qemu/include/qemu/thread.h:16:0,
                 from util/qemu-thread-win32.c:15:
/home/stefanha/qemu/include/qemu/thread-win32.h:15:6: note: previous declaration of 'qemu_rec_mutex_destroy' was here
 void qemu_rec_mutex_destroy(QemuMutex *mutex);
      ^