[Qemu-devel] [PATCH v2 0/5] iothread: create gcontext unconditionally

[Peter Xu <peterx@redhat.com>]

v2:
- add comment in patch 4
- add another patch to comment why we need explicit aio_poll() in
  iothread_run loop

When I first read the iothread code, the gcontext confused me for
quite a while.  Meanwhile, I've been tackling with some races due to
this complexity as well.  How much we'll pay for creating the gcontext
unconditionally?  Do we really need this flexibitily (or is it really
a flexibility after all)?  I don't see much gain of existing code, but
I might be wrong.  Anyway, I wrote this patchset to see how the list
would think about it.

This series directly originates from previous discussion with
Marc-Andre where there's a slightly hacky way to try to acquire the
gcontext:

https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg05460.html

Now with this series logically above patch is not needed any more.
Please read patch 4 for more information.

And if this patchset can survive... how about running gcontext
directly in iothread_run()?  I believe there could be a bit more
things to clean but I'll see.

Make check passes for me.

Comments welcomed.  Thanks,

Peter Xu (5):
  iothread: replace init_done_cond with a semaphore
  iothread: create the gcontext unconditionally
  iothread: create main loop unconditionally
  iothread: push gcontext earlier in the thread_fn
  iothread: document about why we need explicit aio_poll()

 include/sysemu/iothread.h |  5 +--
 iothread.c                | 91 +++++++++++++++++++--------------------
 2 files changed, 46 insertions(+), 50 deletions(-)

-- 
2.17.1