[libvirt] [PATCH] qemu: call endjob in RevertToSnapshot

[Eric Blake]

On 08/27/2014 03:20 AM, Jincheng Miao wrote:
> 
> On 08/27/2014 11:02 AM, Eric Blake wrote:
>> On 08/26/2014 08:10 PM, Jincheng Miao wrote:
>>> In qemuDomainRevertToSnapshot(), it will check snap->def->state.
>>> But when the state is PMSUSPENDED/NOSTATE/BLOCKED, it forgets to
>>> call qemuDomainObjEndJob.
>>>
>>> Signed-off-by: Jincheng Miao <jmiao at redhat.com>
>>> ---
>>>   src/qemu/qemu_driver.c |    4 ++--
>>>   1 files changed, 2 insertions(+), 2 deletions(-)
>> This looks like the fix for
>> https://bugzilla.redhat.com/show_bug.cgi?id=1134154 - thanks for chasing
>> that!
> 
> This patch fix the part of that bug, but it doesn't touch the race
> condition:
> Why the snap->def->state is NOSTATE? It should be RUNNING.
> The only reasonable explanation is that snapshot object is free()ed.
> 
> IMHO, the SnapshotObjList should be clocked during snapshot job running.

Okay, I see what you are saying; we need to make sure two parallel
snapshot operations can't stomp on one another (probably by making them
all guarded by the vm job lock).  I hope to have time to look into a fix
before 1.2.8; but as it has been a long-standing issue, it's not a new
regression in this release if I miss that goal (my priority today is
getting 1.2.8 APIs to be feature-complete).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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