Re: [Qemu-devel] [Qemu-block] [PATCH v2] block: make BDRV_POLL_WHILE() re-entrancy safe

[Stefan Hajnoczi]

On Wed, Mar 07, 2018 at 12:46:19PM +0000, Stefan Hajnoczi wrote:
> Nested BDRV_POLL_WHILE() calls can occur.  Currently
> assert(!wait_->wakeup) fails in AIO_WAIT_WHILE() when this happens.
> 
> This patch converts the bool wait_->need_kick flag to an unsigned
> wait_->num_waiters counter.
> 
> Nesting works correctly because outer AIO_WAIT_WHILE() callers evaluate
> the condition again after the inner caller completes (invoking the inner
> caller counts as aio_poll() progress).
> 
> Reported-by: "fuweiwei (C)" <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
> v2:
>  * Rebase onto qemu.git/master now that AIO_WAIT_WHILE() has landed
>    [Kevin]
> 
>  include/block/aio-wait.h | 61 
> ++++++++++++++++++++++++------------------------
>  util/aio-wait.c          |  2 +-
>  2 files changed, 31 insertions(+), 32 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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