Re: [Qemu-devel] [PATCH v2 03/17] aio-wait: Increase num_waiters even in home thread

[Paolo Bonzini]

On 13/09/2018 14:52, Kevin Wolf wrote:
> Even if AIO_WAIT_WHILE() is called in the home context of the
> AioContext, we still want to allow the condition to change depending on
> other threads as long as they kick the AioWait. Specfically block jobs
> can be running in an I/O thread and should then be able to kick a drain
> in the main loop context.

I don't understand the scenario very well.  Why hasn't the main loop's
drain incremented num_waiters?

Note I'm not against the patch---though I would hoist the
atomic_inc/atomic_dec outside the if, since it's done in both branches.

Paolo