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Date: Thu, 05 Jun 2014 19:29:09 +0200
From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [RFC 2/5] aio: Add io_read_poll() callback
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To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>

On 03.06.2014 19:55, Paolo Bonzini wrote:
> 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.

Thanks; considering Stefan's comment, I'll see whether I can get away 
without implement io_read_poll().

Max

> Paolo