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Date: Tue, 03 Jun 2014 19:55:37 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [RFC 2/5] aio: Add io_read_poll() callback
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To: Max Reitz <mreitz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>

Il 31/05/2014 20:43, Max Reitz ha scritto:
> @@ -108,7 +120,9 @@ bool aio_pending(AioContext *ctx)
>          int revents;
>
>          revents = node->pfd.revents & node->pfd.events;
> -        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
> +        if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read &&
> +            (!node->io_read_poll || node->io_read_poll(node->opaque)))
> +        {
>              return true;
>          }

This would cause a busy loop whenever io_read_poll returns false.  You 
would  need to call io_read_poll when you fill the pollfds array, i.e. 
in aio_poll and aio_ctx_prepare.

Paolo