Re: [RFC PATCH 0/4] async: fix hangs on weakly-ordered architectures

[Stefan Hajnoczi]

On Tue, Apr 07, 2020 at 10:07:41AM -0400, Paolo Bonzini wrote:
> ARM machines and other weakly-ordered architectures have been suffering
> for a long time from hangs in qemu-img and qemu-io.  For QEMU binaries
> these are mitigated by the timers that sooner or later fire in the main
> loop, but these will not happen for the tools and probably not with I/O
> threads either.
> 
> The fix is in patch 5.  Patch 1-3 are docs updates that explain the bug,
> and patch 4 is a bugfix exposed by the new patch.
> 
> Paolo
> 
> Paolo Bonzini (5):
>   atomics: convert to reStructuredText
>   atomics: update documentation
>   rcu: do not mention atomic_mb_read/set in documentation
>   aio-wait: delegate polling of main AioContext if BQL not held
>   async: use explicit memory barriers
> 
>  docs/devel/atomics.rst   | 501 +++++++++++++++++++++++++++++++++++++++
>  docs/devel/atomics.txt   | 403 -------------------------------
>  docs/devel/index.rst     |   1 +
>  docs/devel/rcu.txt       |   4 +-
>  include/block/aio-wait.h |  22 ++
>  include/block/aio.h      |  29 +--
>  util/aio-posix.c         |  16 +-
>  util/aio-win32.c         |  17 +-
>  util/async.c             |  16 +-
>  9 files changed, 576 insertions(+), 433 deletions(-)
>  create mode 100644 docs/devel/atomics.rst
>  delete mode 100644 docs/devel/atomics.txt

Applied patches 4 and 5 to my block branch.

Stefan

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