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Date: Tue, 16 Sep 2014 20:58:45 +0300
From: Chrysostomos Nanakos <cnanakos@grnet.gr>
Message-ID: <20140916175656.GA10502@blackdevil>
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Subject: Re: [Qemu-devel] [PATCH v2] async: aio_context_new(): Handle
 event_notifier_init failure
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To: Chrysostomos Nanakos <cnanakos@grnet.gr>
Cc: =?utf-8?Q?Beno=C3=AEt?= Canet <benoit.canet@irqsave.net>, kwolf@redhat.com, pingfank@linux.vnet.ibm.com, famz@redhat.com, kroosec@gmail.com, jan.kiszka@siemens.com, mjt@tls.msk.ru, qemu-devel@nongnu.org, stefanha@redhat.com, sw@weilnetz.de, Paolo Bonzini <pbonzini@redhat.com>, afaerber@suse.de, aliguori@amazon.com

On Tue, Sep 16, 2014 at 06:50:38PM +0300, Chrysostomos Nanakos wrote:
> On Tue, Sep 16, 2014 at 05:45:16PM +0200, Paolo Bonzini wrote:
> > Il 16/09/2014 17:43, Chrysostomos Nanakos ha scritto:
> > >> >     error_propagate(errp, local_error);
> > >> >     return;
> > > Just to note that after propagating the error and returning, QEMU fails
> > > silently without printing the error message.
> > 
> > What is your testcase?
> 
> I am starting QEMU with the options below and explicitly set iothread->ctx to
> NULL. Is that ok as a testcase or should I reduce my open files limit to
> produce the error?
> 
> qemu --enable-kvm -smp 2 -m 1024 -object iothread,id=iothread0 -drive file=archipelago:fedora_stable
> -vnc 0.0.0.0:0 -qmp tcp:127.0.0.1:8888,server,nowait
> 
> No error message, at least the propagated one, fails silently.
> 
The segfault is caused when QOM tries to object_unref() the iothread object,
type->instance_finalize(obj) is called which calls the registered
iothread_instance_finalize function. A check there for the iothread->ctx
seems to solve the problem.

I will include the fix in the next patch series.

Regards,
Chrysostomos.