From: Stefan Hajnoczi <stefanha@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
Kevin Wolf <kwolf@redhat.com>,
ming.lei@canonical.com,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Dominik Dingel <dingel@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] another locking issue in current dataplane code?
Date: Tue, 8 Jul 2014 17:59:56 +0200 [thread overview]
Message-ID: <20140708155956.GB11505@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <53BA8B49.9050709@de.ibm.com>
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On Mon, Jul 07, 2014 at 01:58:01PM +0200, Christian Borntraeger wrote:
> Now. If aio_poll never returns, we have a deadlock here.
> To me it looks like, that aio_poll could be called from iothread_run, even if there are no outstanding request.
> Opinions?
Christian pointed out that iothread_run() can miss aio_notify() if a
file descriptor becomes readable/writeable at the same time as the
AioContext->notifier. aio_poll() will return true since progress was
made and we are left with a hung QEMU.
I sent Christian an initial patch to fix this but now both threads are
stuck in rfifolock_lock() inside cond wait. That's very strange and
should never happen.
Still trying to figure out what is going on...
Stefan
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next prev parent reply other threads:[~2014-07-08 16:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-07 11:58 [Qemu-devel] another locking issue in current dataplane code? Christian Borntraeger
2014-07-08 7:19 ` Christian Borntraeger
2014-07-08 7:43 ` Ming Lei
2014-07-08 8:38 ` Christian Borntraeger
2014-07-08 9:09 ` Christian Borntraeger
2014-07-08 10:12 ` Christian Borntraeger
2014-07-08 10:37 ` Christian Borntraeger
2014-07-08 11:03 ` Christian Borntraeger
2014-07-08 15:59 ` Stefan Hajnoczi [this message]
2014-07-08 17:08 ` Paolo Bonzini
2014-07-08 19:07 ` Christian Borntraeger
2014-07-08 19:50 ` Paolo Bonzini
2014-07-09 7:56 ` Stefan Hajnoczi
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