[libvirt] [PATCH] qemu: Fix a possible deadlock in p2p migration

[Daniel P. Berrange]

On Fri, Jan 21, 2011 at 04:28:07PM +0800, Wen Congyang wrote:
> The function virUnrefConnect() may call virReleaseConnect() to release
> the dest connection, and the function virReleaseConnect() will call
> conn->driver->close().
> 
> So the function virUnrefConnect() should be surrounded by
> qemuDomainObjEnterRemoteWithDriver() and
> qemuDomainObjExitRemoteWithDriver() to prevent possible deadlock between
> two communicating libvirt daemons.
> 
> See commit f0c8e1cb3774d6f09e2681ca1988bf235a343007 for further details.
> 
> Signed-off-by: Wen Congyang <wency at cn.fujitsu.com>
> 
> ---
>  src/qemu/qemu_driver.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 9eb9cd5..ec142e1 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -8789,7 +8789,9 @@ static int doPeer2PeerMigrate(virDomainPtr dom,
>  cleanup:
>      VIR_FREE(dom_xml);
>      /* don't call virConnectClose(), because that resets any pending errors */
> +    qemuDomainObjEnterRemoteWithDriver(driver, vm);
>      virUnrefConnect(dconn);
> +    qemuDomainObjExitRemoteWithDriver(driver, vm);
>  
>      return ret;

ACK

Daniel