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Date: Thu, 4 Feb 2016 03:53:13 -0500 (EST)
From: Pankaj Gupta <pagupta@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] rng-random: implement request queue
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To: Ladi Prosek <lprosek@redhat.com>
Cc: Amit Shah <amit.shah@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org


Hi Ladi,

I think this is fine if we have multiple requests from Guests and 
depending on entropy pool available we can honour individual requests
and return with the entropy.

Just one point I have is, Suppose we have multiple requests from Guests  
and we are returning if request length < 0 for any request. There might 
be pending requests which will get executed in next iteration?Can we honour
them in same iteration?

static void entropy_available(void *opaque)
 {
...
...
 while (s->requests != NULL) {
...
if (len < 0 && errno == EAGAIN) {
+            return;
+        }
...

Best regards,
Pankaj
> 
> 
> 
> On 03/02/2016 13:36, Amit Shah wrote:
> > ... and this can lead to breaking migration (the queue of requests on
> > the host needs to be migrated, else the new host will have no idea of
> > the queue).
> 
> It is already migrated as part of virtio_rng_save's call to virtio_save.
>  On the loading side, virtio_rng_process condenses all requests into one
> and chr_read fills in as many virtqueue buffers as possible from the
> single request.
> 
> Cancel_requests seems useless.
> 
> Paolo
>