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Date: Tue, 28 Aug 2012 12:05:52 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 10/10] qdev: fix create in place obj's life
	cycle problem
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Liu Ping Fan <pingfank@linux.vnet.ibm.com>, liu ping fan <qemulist@gmail.com>, Anthony Liguori <anthony@codemonkey.ws>, Avi Kivity <avi@redhat.com>

Il 28/08/2012 11:42, Jan Kiszka ha scritto:
> Context A                               Context B
> ---------                               ---------
>                                         object = lookup()
> deregister(object)
> modify(object) -> invalid state
> ...                                     use(object)
> modify(object) -> valid state
> register(object)
> 
> And with "object" I'm not talking about QOM but any data structure.

If you want to avoid locks, the only way to do so is RCU.  Then you do
not modify object at all.

Paolo