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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <1478265017-5700-1-git-send-email-thuth@redhat.com> (Thomas
	Huth's message of "Fri, 4 Nov 2016 14:10:17 +0100")
References: <1478265017-5700-1-git-send-email-thuth@redhat.com>
Reply-To: quintela@redhat.com
Date: Mon, 14 Nov 2016 19:34:59 +0100
Message-ID: <87wpg5di5o.fsf@emacs.mitica>
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Subject: Re: [Qemu-devel] [PATCH for-2.8] migration: Fix return code of
 ram_save_iterate()
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To: Thomas Huth <thuth@redhat.com>
Cc: Amit Shah <amit.shah@redhat.com>, qemu-devel@nongnu.org, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, David Gibson <david@gibson.dropbear.id.au>

Thomas Huth <thuth@redhat.com> wrote:
> qemu_savevm_state_iterate() expects the iterators to return 1
> when they are done, and 0 if there is still something left to do.
> However, ram_save_iterate() does not obey this rule and returns
> the number of saved pages instead. This causes a fatal hang with
> ppc64 guests when you run QEMU like this (also works with TCG):
>
>  qemu-img create -f qcow2  /tmp/test.qcow2 1M
>  qemu-system-ppc64 -nographic -nodefaults -m 256 \
>                    -hda /tmp/test.qcow2 -serial mon:stdio
>
> ... then switch to the monitor by pressing CTRL-a c and try to
> save a snapshot with "savevm test1" for example.
>
> After the first iteration, ram_save_iterate() always returns 0 here,
> so that qemu_savevm_state_iterate() hangs in an endless loop and you
> can only "kill -9" the QEMU process.
> Fix it by using proper return values in ram_save_iterate().
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

Applied.

I don't know how we broked this so much.

Thanks, Juan.